* [PATCH v9 0/8] ARM generic idle states
@ 2014-09-05 17:34 ` Lorenzo Pieralisi
0 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-05 17:34 UTC (permalink / raw)
To: linux-arm-kernel, linux-pm
Cc: devicetree, Lorenzo Pieralisi, Mark Rutland, Sudeep Holla,
Catalin Marinas, Will Deacon, Charles Garcia Tobin, Nicolas Pitre,
Rob Herring, Grant Likely, Peter De Schrijver, Santosh Shilimkar,
Daniel Lezcano, Amit Kucheria, Vincent Guittot, Antti Miettinen,
Stephen Boyd, Kevin Hilman, Sebastian Capella, Mark Brown,
Paul Walmsley, Chander Kashyap, Geoff
This patch is v9 of a previous posting:
http://lists.infradead.org/pipermail/linux-arm-kernel/2014-September/283384.html
Patchset has been tested on:
- Juno ARM64 platform and Foundation v8 models (based on Trusted Firmware
PSCI implementation available at [1])
# Patches to enable idle states on Juno and Foundation models can be made
available, current dts are not in the mainline kernel
- TC2
- Compile tested on Samsung Exynos
Patch for Exynos CPUidle code depends on patch [2].
[1] https://github.com/ARM-software/arm-trusted-firmware
[2] http://lists.infradead.org/pipermail/linux-arm-kernel/2014-July/274179.html
Changes in v9:
- Cosmetic changes to arm64 CPUidle driver (pr_err logs)
- Added acknowledgements
- Reordered the series by splitting arm64 and CPUidle specific bits
Changes in v8:
- Added idle states check on all cpus in the CPUidle driver mask
- Added missing DT nodes ref counting
- Added idle states node matching code to initialize CPUidle enter function
- Added code to fall back on cpu_possible_mask on NULL CPUidle driver cpumask
Changes in v7:
- Refactored arm64 cpu_suspend API to support retention states
- Readded static states tables for TC2 and Exynos CPUidle driver so that
platforms with old dts files will still work as expected
- Slightly reworked the DT parsing API to return the number of parsed DT
states
- Ported PSCI to the new cpu_suspend API, now supporting retention states
- Rebased against 3.16
Changes in v6:
- Added ARM64 CPU init idle to CPU operations
- Removed power-rank property; sorting depends on the cpu-idle-states phandle
list order now
- Added local-timer-stop flag
- Removed useless TC2 and Exynos DT idle state entry-method bindings
- Removed RTSM dts update
- Updated PSCI suspend parameter and DT bindings
- Updated PSCI parsing code
- Rebased against 3.16-rc6
Changes in v5:
- Added power-rank property to implement state sorting, following a number
of on/off list review comments
- Added timer retained bool property
- Ported TC2 big.LITTLE and Exynos drivers to DT initialization
- Renamed s/OF/dt/ throughout the patch
- Incorporated review comments and list discussions in the idle states
bindings documents
- Rebased against 3.16-rc2
Changes in v4:
- States sorting using exit-latency
- Added cosmetic review comments
- Dropped RFC
- Rebased against 3.15
Changes in v3:
- Streamlined the idle states bindings and added them to the series
http://www.spinics.net/lists/arm-kernel/msg316299.html
- Sorting states through min-residency+exit-latency
- Added debug strings formatting
- Reworded min-residency-us idle state property
- Removed power-domain properties from idle states waiting for code
examples requiring them to be defined
Changes in v2:
- Moved OF parsing code to drivers/cpuidle
- Improved states detection and sorting through linked list
- Split code in generic and ARM64 specific bits
- Moved idle enter function into ARM64 idle driver
- Refactored PSCI idle states register function
- Renamed suspend operations and moved detection to ARM64 idle driver
- Changed the way CPUIDLE_FLAG_TIMER_STOP is handled
- Simplified idle state nodes parsing since according to the latest
bindings idle state nodes are a flat list, not hierarchical anymore
- Used min-residency-us to sort the states, to be further discussed
Idle states on most ARM platforms can be characterized by a set of
parameters that are platform agnostic and describe the HW idle states
features. So far, CPU idle drivers for ARM platforms required the definition
of parameters through static tables, duplicating control data for different
platforms. Moreover, the lack of standardization on firmware interfaces
hampered any standardization effort, resulting in CPU idle drivers for ARM
platforms containing duplicated code and platform specific power down routines.
The introduction of the PSCI firmware interface, and more in general, well
defined suspend back-ends, allows the definition of generic idle states and
the respective kernel infrastructure to support them.
Building on top of DT idle states bindings, that standardize idle states
parameters and corresponding suspend back-ends, this patchset provides code
that parses DT idle states nodes and builds at run-time the control data
infrastructure required by the ARM CPU idle drivers.
Idle states define an entry method (eg PSCI), that requires the respective
ARM64 kernel back-end to be invoked to initialize idle states parameters, so
that when the idle driver executes the back-end specific entry method a table
look-up can be carried out to retrieve the corresponding idle state parameter.
On legacy ARM platforms the DT idle states are used to initialize states
data and the idle state compatible string allows to match the corresponding
idle state enter function and initialize the enter function pointer
accordingly.
Lorenzo Pieralisi (8):
Documentation: arm: define DT idle states bindings
arm64: kernel: refactor the CPU suspend API for retention states
arm64: kernel: introduce cpu_init_idle CPU operation
arm64: add PSCI CPU_SUSPEND based cpu_suspend support
drivers: cpuidle: implement DT based idle states infrastructure
drivers: cpuidle: CPU idle ARM64 driver
drivers: cpuidle: initialize big.LITTLE driver through DT
drivers: cpuidle: initialize Exynos driver through DT
Documentation/devicetree/bindings/arm/cpus.txt | 8 +
.../devicetree/bindings/arm/idle-states.txt | 679 +++++++++++++++++++++
Documentation/devicetree/bindings/arm/psci.txt | 14 +-
arch/arm/boot/dts/exynos4210.dtsi | 11 +
arch/arm/boot/dts/exynos5250.dtsi | 11 +
arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts | 23 +
arch/arm64/include/asm/cpu_ops.h | 3 +
arch/arm64/include/asm/cpuidle.h | 13 +
arch/arm64/include/asm/suspend.h | 1 +
arch/arm64/kernel/Makefile | 1 +
arch/arm64/kernel/cpuidle.c | 31 +
arch/arm64/kernel/psci.c | 104 ++++
arch/arm64/kernel/sleep.S | 47 +-
arch/arm64/kernel/suspend.c | 48 +-
drivers/cpuidle/Kconfig | 8 +
drivers/cpuidle/Kconfig.arm | 2 +
drivers/cpuidle/Kconfig.arm64 | 14 +
drivers/cpuidle/Makefile | 5 +
drivers/cpuidle/cpuidle-arm64.c | 133 ++++
drivers/cpuidle/cpuidle-big_little.c | 19 +
drivers/cpuidle/cpuidle-exynos.c | 18 +-
drivers/cpuidle/dt_idle_states.c | 213 +++++++
drivers/cpuidle/dt_idle_states.h | 7 +
23 files changed, 1379 insertions(+), 34 deletions(-)
create mode 100644 Documentation/devicetree/bindings/arm/idle-states.txt
create mode 100644 arch/arm64/include/asm/cpuidle.h
create mode 100644 arch/arm64/kernel/cpuidle.c
create mode 100644 drivers/cpuidle/Kconfig.arm64
create mode 100644 drivers/cpuidle/cpuidle-arm64.c
create mode 100644 drivers/cpuidle/dt_idle_states.c
create mode 100644 drivers/cpuidle/dt_idle_states.h
--
1.9.1
^ permalink raw reply [flat|nested] 29+ messages in thread
* [PATCH v9 0/8] ARM generic idle states
@ 2014-09-05 17:34 ` Lorenzo Pieralisi
0 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-05 17:34 UTC (permalink / raw)
To: linux-arm-kernel
This patch is v9 of a previous posting:
http://lists.infradead.org/pipermail/linux-arm-kernel/2014-September/283384.html
Patchset has been tested on:
- Juno ARM64 platform and Foundation v8 models (based on Trusted Firmware
PSCI implementation available at [1])
# Patches to enable idle states on Juno and Foundation models can be made
available, current dts are not in the mainline kernel
- TC2
- Compile tested on Samsung Exynos
Patch for Exynos CPUidle code depends on patch [2].
[1] https://github.com/ARM-software/arm-trusted-firmware
[2] http://lists.infradead.org/pipermail/linux-arm-kernel/2014-July/274179.html
Changes in v9:
- Cosmetic changes to arm64 CPUidle driver (pr_err logs)
- Added acknowledgements
- Reordered the series by splitting arm64 and CPUidle specific bits
Changes in v8:
- Added idle states check on all cpus in the CPUidle driver mask
- Added missing DT nodes ref counting
- Added idle states node matching code to initialize CPUidle enter function
- Added code to fall back on cpu_possible_mask on NULL CPUidle driver cpumask
Changes in v7:
- Refactored arm64 cpu_suspend API to support retention states
- Readded static states tables for TC2 and Exynos CPUidle driver so that
platforms with old dts files will still work as expected
- Slightly reworked the DT parsing API to return the number of parsed DT
states
- Ported PSCI to the new cpu_suspend API, now supporting retention states
- Rebased against 3.16
Changes in v6:
- Added ARM64 CPU init idle to CPU operations
- Removed power-rank property; sorting depends on the cpu-idle-states phandle
list order now
- Added local-timer-stop flag
- Removed useless TC2 and Exynos DT idle state entry-method bindings
- Removed RTSM dts update
- Updated PSCI suspend parameter and DT bindings
- Updated PSCI parsing code
- Rebased against 3.16-rc6
Changes in v5:
- Added power-rank property to implement state sorting, following a number
of on/off list review comments
- Added timer retained bool property
- Ported TC2 big.LITTLE and Exynos drivers to DT initialization
- Renamed s/OF/dt/ throughout the patch
- Incorporated review comments and list discussions in the idle states
bindings documents
- Rebased against 3.16-rc2
Changes in v4:
- States sorting using exit-latency
- Added cosmetic review comments
- Dropped RFC
- Rebased against 3.15
Changes in v3:
- Streamlined the idle states bindings and added them to the series
http://www.spinics.net/lists/arm-kernel/msg316299.html
- Sorting states through min-residency+exit-latency
- Added debug strings formatting
- Reworded min-residency-us idle state property
- Removed power-domain properties from idle states waiting for code
examples requiring them to be defined
Changes in v2:
- Moved OF parsing code to drivers/cpuidle
- Improved states detection and sorting through linked list
- Split code in generic and ARM64 specific bits
- Moved idle enter function into ARM64 idle driver
- Refactored PSCI idle states register function
- Renamed suspend operations and moved detection to ARM64 idle driver
- Changed the way CPUIDLE_FLAG_TIMER_STOP is handled
- Simplified idle state nodes parsing since according to the latest
bindings idle state nodes are a flat list, not hierarchical anymore
- Used min-residency-us to sort the states, to be further discussed
Idle states on most ARM platforms can be characterized by a set of
parameters that are platform agnostic and describe the HW idle states
features. So far, CPU idle drivers for ARM platforms required the definition
of parameters through static tables, duplicating control data for different
platforms. Moreover, the lack of standardization on firmware interfaces
hampered any standardization effort, resulting in CPU idle drivers for ARM
platforms containing duplicated code and platform specific power down routines.
The introduction of the PSCI firmware interface, and more in general, well
defined suspend back-ends, allows the definition of generic idle states and
the respective kernel infrastructure to support them.
Building on top of DT idle states bindings, that standardize idle states
parameters and corresponding suspend back-ends, this patchset provides code
that parses DT idle states nodes and builds at run-time the control data
infrastructure required by the ARM CPU idle drivers.
Idle states define an entry method (eg PSCI), that requires the respective
ARM64 kernel back-end to be invoked to initialize idle states parameters, so
that when the idle driver executes the back-end specific entry method a table
look-up can be carried out to retrieve the corresponding idle state parameter.
On legacy ARM platforms the DT idle states are used to initialize states
data and the idle state compatible string allows to match the corresponding
idle state enter function and initialize the enter function pointer
accordingly.
Lorenzo Pieralisi (8):
Documentation: arm: define DT idle states bindings
arm64: kernel: refactor the CPU suspend API for retention states
arm64: kernel: introduce cpu_init_idle CPU operation
arm64: add PSCI CPU_SUSPEND based cpu_suspend support
drivers: cpuidle: implement DT based idle states infrastructure
drivers: cpuidle: CPU idle ARM64 driver
drivers: cpuidle: initialize big.LITTLE driver through DT
drivers: cpuidle: initialize Exynos driver through DT
Documentation/devicetree/bindings/arm/cpus.txt | 8 +
.../devicetree/bindings/arm/idle-states.txt | 679 +++++++++++++++++++++
Documentation/devicetree/bindings/arm/psci.txt | 14 +-
arch/arm/boot/dts/exynos4210.dtsi | 11 +
arch/arm/boot/dts/exynos5250.dtsi | 11 +
arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts | 23 +
arch/arm64/include/asm/cpu_ops.h | 3 +
arch/arm64/include/asm/cpuidle.h | 13 +
arch/arm64/include/asm/suspend.h | 1 +
arch/arm64/kernel/Makefile | 1 +
arch/arm64/kernel/cpuidle.c | 31 +
arch/arm64/kernel/psci.c | 104 ++++
arch/arm64/kernel/sleep.S | 47 +-
arch/arm64/kernel/suspend.c | 48 +-
drivers/cpuidle/Kconfig | 8 +
drivers/cpuidle/Kconfig.arm | 2 +
drivers/cpuidle/Kconfig.arm64 | 14 +
drivers/cpuidle/Makefile | 5 +
drivers/cpuidle/cpuidle-arm64.c | 133 ++++
drivers/cpuidle/cpuidle-big_little.c | 19 +
drivers/cpuidle/cpuidle-exynos.c | 18 +-
drivers/cpuidle/dt_idle_states.c | 213 +++++++
drivers/cpuidle/dt_idle_states.h | 7 +
23 files changed, 1379 insertions(+), 34 deletions(-)
create mode 100644 Documentation/devicetree/bindings/arm/idle-states.txt
create mode 100644 arch/arm64/include/asm/cpuidle.h
create mode 100644 arch/arm64/kernel/cpuidle.c
create mode 100644 drivers/cpuidle/Kconfig.arm64
create mode 100644 drivers/cpuidle/cpuidle-arm64.c
create mode 100644 drivers/cpuidle/dt_idle_states.c
create mode 100644 drivers/cpuidle/dt_idle_states.h
--
1.9.1
^ permalink raw reply [flat|nested] 29+ messages in thread
* [PATCH v9 1/8] Documentation: arm: define DT idle states bindings
2014-09-05 17:34 ` Lorenzo Pieralisi
@ 2014-09-05 17:34 ` Lorenzo Pieralisi
-1 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-05 17:34 UTC (permalink / raw)
To: linux-arm-kernel, linux-pm
Cc: devicetree, Lorenzo Pieralisi, Mark Rutland, Sudeep Holla,
Catalin Marinas, Will Deacon, Charles Garcia Tobin, Nicolas Pitre,
Rob Herring, Grant Likely, Peter De Schrijver, Santosh Shilimkar,
Daniel Lezcano, Amit Kucheria, Vincent Guittot, Antti Miettinen,
Stephen Boyd, Kevin Hilman, Sebastian Capella, Mark Brown,
Paul Walmsley, Chander Kashyap, Geoff
ARM based platforms implement a variety of power management schemes that
allow processors to enter idle states at run-time.
The parameters defining these idle states vary on a per-platform basis forcing
the OS to hardcode the state parameters in platform specific static tables
whose size grows as the number of platforms supported in the kernel increases
and hampers device drivers standardization.
Therefore, this patch aims at standardizing idle state device tree bindings
for ARM platforms. Bindings define idle state parameters inclusive of entry
methods and state latencies, to allow operating systems to retrieve the
configuration entries from the device tree and initialize the related power
management drivers, paving the way for common code in the kernel to deal with
idle states and removing the need for static data in current and previous
kernel versions.
ARM64 platforms require the DT to define an entry-method property
for idle states.
On system implementing PSCI as an enable-method to enter low-power
states the PSCI CPU suspend method requires the power_state parameter to
be passed to the PSCI CPU suspend function.
This parameter is specific to a power state and platform specific,
therefore must be provided by firmware to the OS in order to enable
proper call sequence.
Thus, this patch also adds a property in the PSCI bindings that
describes how the PSCI CPU suspend power_state parameter should be
defined in DT in all device nodes that rely on PSCI CPU suspend method usage.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Sebastian Capella <sebcape@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
Documentation/devicetree/bindings/arm/cpus.txt | 8 +
.../devicetree/bindings/arm/idle-states.txt | 679 +++++++++++++++++++++
Documentation/devicetree/bindings/arm/psci.txt | 14 +-
3 files changed, 700 insertions(+), 1 deletion(-)
create mode 100644 Documentation/devicetree/bindings/arm/idle-states.txt
diff --git a/Documentation/devicetree/bindings/arm/cpus.txt b/Documentation/devicetree/bindings/arm/cpus.txt
index 298e2f6..6fd0f15 100644
--- a/Documentation/devicetree/bindings/arm/cpus.txt
+++ b/Documentation/devicetree/bindings/arm/cpus.txt
@@ -219,6 +219,12 @@ nodes to be present and contain the properties described below.
Value type: <phandle>
Definition: Specifies the ACC[2] node associated with this CPU.
+ - cpu-idle-states
+ Usage: Optional
+ Value type: <prop-encoded-array>
+ Definition:
+ # List of phandles to idle state nodes supported
+ by this cpu [3].
Example 1 (dual-cluster big.LITTLE system 32-bit):
@@ -415,3 +421,5 @@ cpus {
--
[1] arm/msm/qcom,saw2.txt
[2] arm/msm/qcom,kpss-acc.txt
+[3] ARM Linux kernel documentation - idle states bindings
+ Documentation/devicetree/bindings/arm/idle-states.txt
diff --git a/Documentation/devicetree/bindings/arm/idle-states.txt b/Documentation/devicetree/bindings/arm/idle-states.txt
new file mode 100644
index 0000000..37375c7
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/idle-states.txt
@@ -0,0 +1,679 @@
+==========================================
+ARM idle states binding description
+==========================================
+
+==========================================
+1 - Introduction
+==========================================
+
+ARM systems contain HW capable of managing power consumption dynamically,
+where cores can be put in different low-power states (ranging from simple
+wfi to power gating) according to OS PM policies. The CPU states representing
+the range of dynamic idle states that a processor can enter at run-time, can be
+specified through device tree bindings representing the parameters required
+to enter/exit specific idle states on a given processor.
+
+According to the Server Base System Architecture document (SBSA, [3]), the
+power states an ARM CPU can be put into are identified by the following list:
+
+- Running
+- Idle_standby
+- Idle_retention
+- Sleep
+- Off
+
+The power states described in the SBSA document define the basic CPU states on
+top of which ARM platforms implement power management schemes that allow an OS
+PM implementation to put the processor in different idle states (which include
+states listed above; "off" state is not an idle state since it does not have
+wake-up capabilities, hence it is not considered in this document).
+
+Idle state parameters (eg entry latency) are platform specific and need to be
+characterized with bindings that provide the required information to OS PM
+code so that it can build the required tables and use them at runtime.
+
+The device tree binding definition for ARM idle states is the subject of this
+document.
+
+===========================================
+2 - idle-states definitions
+===========================================
+
+Idle states are characterized for a specific system through a set of
+timing and energy related properties, that underline the HW behaviour
+triggered upon idle states entry and exit.
+
+The following diagram depicts the CPU execution phases and related timing
+properties required to enter and exit an idle state:
+
+..__[EXEC]__|__[PREP]__|__[ENTRY]__|__[IDLE]__|__[EXIT]__|__[EXEC]__..
+ | | | | |
+
+ |<------ entry ------->|
+ | latency |
+ |<- exit ->|
+ | latency |
+ |<-------- min-residency -------->|
+ |<------- wakeup-latency ------->|
+
+ Diagram 1: CPU idle state execution phases
+
+EXEC: Normal CPU execution.
+
+PREP: Preparation phase before committing the hardware to idle mode
+ like cache flushing. This is abortable on pending wake-up
+ event conditions. The abort latency is assumed to be negligible
+ (i.e. less than the ENTRY + EXIT duration). If aborted, CPU
+ goes back to EXEC. This phase is optional. If not abortable,
+ this should be included in the ENTRY phase instead.
+
+ENTRY: The hardware is committed to idle mode. This period must run
+ to completion up to IDLE before anything else can happen.
+
+IDLE: This is the actual energy-saving idle period. This may last
+ between 0 and infinite time, until a wake-up event occurs.
+
+EXIT: Period during which the CPU is brought back to operational
+ mode (EXEC).
+
+entry-latency: Worst case latency required to enter the idle state. The
+exit-latency may be guaranteed only after entry-latency has passed.
+
+min-residency: Minimum period, including preparation and entry, for a given
+idle state to be worthwhile energywise.
+
+wakeup-latency: Maximum delay between the signaling of a wake-up event and the
+CPU being able to execute normal code again. If not specified, this is assumed
+to be entry-latency + exit-latency.
+
+These timing parameters can be used by an OS in different circumstances.
+
+An idle CPU requires the expected min-residency time to select the most
+appropriate idle state based on the expected expiry time of the next IRQ
+(ie wake-up) that causes the CPU to return to the EXEC phase.
+
+An operating system scheduler may need to compute the shortest wake-up delay
+for CPUs in the system by detecting how long will it take to get a CPU out
+of an idle state, eg:
+
+wakeup-delay = exit-latency + max(entry-latency - (now - entry-timestamp), 0)
+
+In other words, the scheduler can make its scheduling decision by selecting
+(eg waking-up) the CPU with the shortest wake-up latency.
+The wake-up latency must take into account the entry latency if that period
+has not expired. The abortable nature of the PREP period can be ignored
+if it cannot be relied upon (e.g. the PREP deadline may occur much sooner than
+the worst case since it depends on the CPU operating conditions, ie caches
+state).
+
+An OS has to reliably probe the wakeup-latency since some devices can enforce
+latency constraints guarantees to work properly, so the OS has to detect the
+worst case wake-up latency it can incur if a CPU is allowed to enter an
+idle state, and possibly to prevent that to guarantee reliable device
+functioning.
+
+The min-residency time parameter deserves further explanation since it is
+expressed in time units but must factor in energy consumption coefficients.
+
+The energy consumption of a cpu when it enters a power state can be roughly
+characterised by the following graph:
+
+ |
+ |
+ |
+ e |
+ n | /---
+ e | /------
+ r | /------
+ g | /-----
+ y | /------
+ | ----
+ | /|
+ | / |
+ | / |
+ | / |
+ | / |
+ | / |
+ |/ |
+ -----|-------+----------------------------------
+ 0| 1 time(ms)
+
+ Graph 1: Energy vs time example
+
+The graph is split in two parts delimited by time 1ms on the X-axis.
+The graph curve with X-axis values = { x | 0 < x < 1ms } has a steep slope
+and denotes the energy costs incurred whilst entering and leaving the idle
+state.
+The graph curve in the area delimited by X-axis values = {x | x > 1ms } has
+shallower slope and essentially represents the energy consumption of the idle
+state.
+
+min-residency is defined for a given idle state as the minimum expected
+residency time for a state (inclusive of preparation and entry) after
+which choosing that state become the most energy efficient option. A good
+way to visualise this, is by taking the same graph above and comparing some
+states energy consumptions plots.
+
+For sake of simplicity, let's consider a system with two idle states IDLE1,
+and IDLE2:
+
+ |
+ |
+ |
+ | /-- IDLE1
+ e | /---
+ n | /----
+ e | /---
+ r | /-----/--------- IDLE2
+ g | /-------/---------
+ y | ------------ /---|
+ | / /---- |
+ | / /--- |
+ | / /---- |
+ | / /--- |
+ | --- |
+ | / |
+ | / |
+ |/ | time
+ ---/----------------------------+------------------------
+ |IDLE1-energy < IDLE2-energy | IDLE2-energy < IDLE1-energy
+ |
+ IDLE2-min-residency
+
+ Graph 2: idle states min-residency example
+
+In graph 2 above, that takes into account idle states entry/exit energy
+costs, it is clear that if the idle state residency time (ie time till next
+wake-up IRQ) is less than IDLE2-min-residency, IDLE1 is the better idle state
+choice energywise.
+
+This is mainly down to the fact that IDLE1 entry/exit energy costs are lower
+than IDLE2.
+
+However, the lower power consumption (ie shallower energy curve slope) of idle
+state IDLE2 implies that after a suitable time, IDLE2 becomes more energy
+efficient.
+
+The time at which IDLE2 becomes more energy efficient than IDLE1 (and other
+shallower states in a system with multiple idle states) is defined
+IDLE2-min-residency and corresponds to the time when energy consumption of
+IDLE1 and IDLE2 states breaks even.
+
+The definitions provided in this section underpin the idle states
+properties specification that is the subject of the following sections.
+
+===========================================
+3 - idle-states node
+===========================================
+
+ARM processor idle states are defined within the idle-states node, which is
+a direct child of the cpus node [1] and provides a container where the
+processor idle states, defined as device tree nodes, are listed.
+
+- idle-states node
+
+ Usage: Optional - On ARM systems, it is a container of processor idle
+ states nodes. If the system does not provide CPU
+ power management capabilities or the processor just
+ supports idle_standby an idle-states node is not
+ required.
+
+ Description: idle-states node is a container node, where its
+ subnodes describe the CPU idle states.
+
+ Node name must be "idle-states".
+
+ The idle-states node's parent node must be the cpus node.
+
+ The idle-states node's child nodes can be:
+
+ - one or more state nodes
+
+ Any other configuration is considered invalid.
+
+ An idle-states node defines the following properties:
+
+ - entry-method
+ Value type: <stringlist>
+ Usage and definition depend on ARM architecture version.
+ # On ARM v8 64-bit this property is required and must
+ be one of:
+ - "psci" (see bindings in [2])
+ # On ARM 32-bit systems this property is optional
+
+The nodes describing the idle states (state) can only be defined within the
+idle-states node, any other configuration is considered invalid and therefore
+must be ignored.
+
+===========================================
+4 - state node
+===========================================
+
+A state node represents an idle state description and must be defined as
+follows:
+
+- state node
+
+ Description: must be child of the idle-states node
+
+ The state node name shall follow standard device tree naming
+ rules ([5], 2.2.1 "Node names"), in particular state nodes which
+ are siblings within a single common parent must be given a unique name.
+
+ The idle state entered by executing the wfi instruction (idle_standby
+ SBSA,[3][4]) is considered standard on all ARM platforms and therefore
+ must not be listed.
+
+ With the definitions provided above, the following list represents
+ the valid properties for a state node:
+
+ - compatible
+ Usage: Required
+ Value type: <stringlist>
+ Definition: Must be "arm,idle-state".
+
+ - local-timer-stop
+ Usage: See definition
+ Value type: <none>
+ Definition: if present the CPU local timer control logic is
+ lost on state entry, otherwise it is retained.
+
+ - entry-latency-us
+ Usage: Required
+ Value type: <prop-encoded-array>
+ Definition: u32 value representing worst case latency in
+ microseconds required to enter the idle state.
+ The exit-latency-us duration may be guaranteed
+ only after entry-latency-us has passed.
+
+ - exit-latency-us
+ Usage: Required
+ Value type: <prop-encoded-array>
+ Definition: u32 value representing worst case latency
+ in microseconds required to exit the idle state.
+
+ - min-residency-us
+ Usage: Required
+ Value type: <prop-encoded-array>
+ Definition: u32 value representing minimum residency duration
+ in microseconds, inclusive of preparation and
+ entry, for this idle state to be considered
+ worthwhile energy wise (refer to section 2 of
+ this document for a complete description).
+
+ - wakeup-latency-us:
+ Usage: Optional
+ Value type: <prop-encoded-array>
+ Definition: u32 value representing maximum delay between the
+ signaling of a wake-up event and the CPU being
+ able to execute normal code again. If omitted,
+ this is assumed to be equal to:
+
+ entry-latency-us + exit-latency-us
+
+ It is important to supply this value on systems
+ where the duration of PREP phase (see diagram 1,
+ section 2) is non-neglibigle.
+ In such systems entry-latency-us + exit-latency-us
+ will exceed wakeup-latency-us by this duration.
+
+ In addition to the properties listed above, a state node may require
+ additional properties specifics to the entry-method defined in the
+ idle-states node, please refer to the entry-method bindings
+ documentation for properties definitions.
+
+===========================================
+4 - Examples
+===========================================
+
+Example 1 (ARM 64-bit, 16-cpu system, PSCI enable-method):
+
+cpus {
+ #size-cells = <0>;
+ #address-cells = <2>;
+
+ CPU0: cpu@0 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a57";
+ reg = <0x0 0x0>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_0_0 &CPU_SLEEP_0_0
+ &CLUSTER_RETENTION_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU1: cpu@1 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a57";
+ reg = <0x0 0x1>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_0_0 &CPU_SLEEP_0_0
+ &CLUSTER_RETENTION_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU2: cpu@100 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a57";
+ reg = <0x0 0x100>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_0_0 &CPU_SLEEP_0_0
+ &CLUSTER_RETENTION_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU3: cpu@101 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a57";
+ reg = <0x0 0x101>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_0_0 &CPU_SLEEP_0_0
+ &CLUSTER_RETENTION_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU4: cpu@10000 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a57";
+ reg = <0x0 0x10000>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_0_0 &CPU_SLEEP_0_0
+ &CLUSTER_RETENTION_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU5: cpu@10001 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a57";
+ reg = <0x0 0x10001>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_0_0 &CPU_SLEEP_0_0
+ &CLUSTER_RETENTION_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU6: cpu@10100 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a57";
+ reg = <0x0 0x10100>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_0_0 &CPU_SLEEP_0_0
+ &CLUSTER_RETENTION_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU7: cpu@10101 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a57";
+ reg = <0x0 0x10101>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_0_0 &CPU_SLEEP_0_0
+ &CLUSTER_RETENTION_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU8: cpu@100000000 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a53";
+ reg = <0x1 0x0>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_1_0 &CPU_SLEEP_1_0
+ &CLUSTER_RETENTION_1 &CLUSTER_SLEEP_1>;
+ };
+
+ CPU9: cpu@100000001 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a53";
+ reg = <0x1 0x1>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_1_0 &CPU_SLEEP_1_0
+ &CLUSTER_RETENTION_1 &CLUSTER_SLEEP_1>;
+ };
+
+ CPU10: cpu@100000100 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a53";
+ reg = <0x1 0x100>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_1_0 &CPU_SLEEP_1_0
+ &CLUSTER_RETENTION_1 &CLUSTER_SLEEP_1>;
+ };
+
+ CPU11: cpu@100000101 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a53";
+ reg = <0x1 0x101>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_1_0 &CPU_SLEEP_1_0
+ &CLUSTER_RETENTION_1 &CLUSTER_SLEEP_1>;
+ };
+
+ CPU12: cpu@100010000 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a53";
+ reg = <0x1 0x10000>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_1_0 &CPU_SLEEP_1_0
+ &CLUSTER_RETENTION_1 &CLUSTER_SLEEP_1>;
+ };
+
+ CPU13: cpu@100010001 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a53";
+ reg = <0x1 0x10001>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_1_0 &CPU_SLEEP_1_0
+ &CLUSTER_RETENTION_1 &CLUSTER_SLEEP_1>;
+ };
+
+ CPU14: cpu@100010100 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a53";
+ reg = <0x1 0x10100>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_1_0 &CPU_SLEEP_1_0
+ &CLUSTER_RETENTION_1 &CLUSTER_SLEEP_1>;
+ };
+
+ CPU15: cpu@100010101 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a53";
+ reg = <0x1 0x10101>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_1_0 &CPU_SLEEP_1_0
+ &CLUSTER_RETENTION_1 &CLUSTER_SLEEP_1>;
+ };
+
+ idle-states {
+ entry-method = "arm,psci";
+
+ CPU_RETENTION_0_0: cpu-retention-0-0 {
+ compatible = "arm,idle-state";
+ arm,psci-suspend-param = <0x0010000>;
+ entry-latency-us = <20>;
+ exit-latency-us = <40>;
+ min-residency-us = <80>;
+ };
+
+ CLUSTER_RETENTION_0: cluster-retention-0 {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ arm,psci-suspend-param = <0x1010000>;
+ entry-latency-us = <50>;
+ exit-latency-us = <100>;
+ min-residency-us = <250>;
+ wakeup-latency-us = <130>;
+ };
+
+ CPU_SLEEP_0_0: cpu-sleep-0-0 {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ arm,psci-suspend-param = <0x0010000>;
+ entry-latency-us = <250>;
+ exit-latency-us = <500>;
+ min-residency-us = <950>;
+ };
+
+ CLUSTER_SLEEP_0: cluster-sleep-0 {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ arm,psci-suspend-param = <0x1010000>;
+ entry-latency-us = <600>;
+ exit-latency-us = <1100>;
+ min-residency-us = <2700>;
+ wakeup-latency-us = <1500>;
+ };
+
+ CPU_RETENTION_1_0: cpu-retention-1-0 {
+ compatible = "arm,idle-state";
+ arm,psci-suspend-param = <0x0010000>;
+ entry-latency-us = <20>;
+ exit-latency-us = <40>;
+ min-residency-us = <90>;
+ };
+
+ CLUSTER_RETENTION_1: cluster-retention-1 {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ arm,psci-suspend-param = <0x1010000>;
+ entry-latency-us = <50>;
+ exit-latency-us = <100>;
+ min-residency-us = <270>;
+ wakeup-latency-us = <100>;
+ };
+
+ CPU_SLEEP_1_0: cpu-sleep-1-0 {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ arm,psci-suspend-param = <0x0010000>;
+ entry-latency-us = <70>;
+ exit-latency-us = <100>;
+ min-residency-us = <300>;
+ wakeup-latency-us = <150>;
+ };
+
+ CLUSTER_SLEEP_1: cluster-sleep-1 {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ arm,psci-suspend-param = <0x1010000>;
+ entry-latency-us = <500>;
+ exit-latency-us = <1200>;
+ min-residency-us = <3500>;
+ wakeup-latency-us = <1300>;
+ };
+ };
+
+};
+
+Example 2 (ARM 32-bit, 8-cpu system, two clusters):
+
+cpus {
+ #size-cells = <0>;
+ #address-cells = <1>;
+
+ CPU0: cpu@0 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a15";
+ reg = <0x0>;
+ cpu-idle-states = <&CPU_SLEEP_0_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU1: cpu@1 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a15";
+ reg = <0x1>;
+ cpu-idle-states = <&CPU_SLEEP_0_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU2: cpu@2 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a15";
+ reg = <0x2>;
+ cpu-idle-states = <&CPU_SLEEP_0_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU3: cpu@3 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a15";
+ reg = <0x3>;
+ cpu-idle-states = <&CPU_SLEEP_0_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU4: cpu@100 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a7";
+ reg = <0x100>;
+ cpu-idle-states = <&CPU_SLEEP_1_0 &CLUSTER_SLEEP_1>;
+ };
+
+ CPU5: cpu@101 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a7";
+ reg = <0x101>;
+ cpu-idle-states = <&CPU_SLEEP_1_0 &CLUSTER_SLEEP_1>;
+ };
+
+ CPU6: cpu@102 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a7";
+ reg = <0x102>;
+ cpu-idle-states = <&CPU_SLEEP_1_0 &CLUSTER_SLEEP_1>;
+ };
+
+ CPU7: cpu@103 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a7";
+ reg = <0x103>;
+ cpu-idle-states = <&CPU_SLEEP_1_0 &CLUSTER_SLEEP_1>;
+ };
+
+ idle-states {
+ CPU_SLEEP_0_0: cpu-sleep-0-0 {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ entry-latency-us = <200>;
+ exit-latency-us = <100>;
+ min-residency-us = <400>;
+ wakeup-latency-us = <250>;
+ };
+
+ CLUSTER_SLEEP_0: cluster-sleep-0 {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ entry-latency-us = <500>;
+ exit-latency-us = <1500>;
+ min-residency-us = <2500>;
+ wakeup-latency-us = <1700>;
+ };
+
+ CPU_SLEEP_1_0: cpu-sleep-1-0 {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ entry-latency-us = <300>;
+ exit-latency-us = <500>;
+ min-residency-us = <900>;
+ wakeup-latency-us = <600>;
+ };
+
+ CLUSTER_SLEEP_1: cluster-sleep-1 {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ entry-latency-us = <800>;
+ exit-latency-us = <2000>;
+ min-residency-us = <6500>;
+ wakeup-latency-us = <2300>;
+ };
+ };
+
+};
+
+===========================================
+5 - References
+===========================================
+
+[1] ARM Linux Kernel documentation - CPUs bindings
+ Documentation/devicetree/bindings/arm/cpus.txt
+
+[2] ARM Linux Kernel documentation - PSCI bindings
+ Documentation/devicetree/bindings/arm/psci.txt
+
+[3] ARM Server Base System Architecture (SBSA)
+ http://infocenter.arm.com/help/index.jsp
+
+[4] ARM Architecture Reference Manuals
+ http://infocenter.arm.com/help/index.jsp
+
+[5] ePAPR standard
+ https://www.power.org/documentation/epapr-version-1-1/
diff --git a/Documentation/devicetree/bindings/arm/psci.txt b/Documentation/devicetree/bindings/arm/psci.txt
index b4a58f3..5aa40ed 100644
--- a/Documentation/devicetree/bindings/arm/psci.txt
+++ b/Documentation/devicetree/bindings/arm/psci.txt
@@ -50,6 +50,16 @@ Main node optional properties:
- migrate : Function ID for MIGRATE operation
+Device tree nodes that require usage of PSCI CPU_SUSPEND function (ie idle
+state nodes, as per bindings in [1]) must specify the following properties:
+
+- arm,psci-suspend-param
+ Usage: Required for state nodes[1] if the corresponding
+ idle-states node entry-method property is set
+ to "psci".
+ Value type: <u32>
+ Definition: power_state parameter to pass to the PSCI
+ suspend call.
Example:
@@ -64,7 +74,6 @@ Case 1: PSCI v0.1 only.
migrate = <0x95c10003>;
};
-
Case 2: PSCI v0.2 only
psci {
@@ -88,3 +97,6 @@ Case 3: PSCI v0.2 and PSCI v0.1.
...
};
+
+[1] Kernel documentation - ARM idle states bindings
+ Documentation/devicetree/bindings/arm/idle-states.txt
--
1.9.1
^ permalink raw reply related [flat|nested] 29+ messages in thread
* [PATCH v9 1/8] Documentation: arm: define DT idle states bindings
@ 2014-09-05 17:34 ` Lorenzo Pieralisi
0 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-05 17:34 UTC (permalink / raw)
To: linux-arm-kernel
ARM based platforms implement a variety of power management schemes that
allow processors to enter idle states at run-time.
The parameters defining these idle states vary on a per-platform basis forcing
the OS to hardcode the state parameters in platform specific static tables
whose size grows as the number of platforms supported in the kernel increases
and hampers device drivers standardization.
Therefore, this patch aims at standardizing idle state device tree bindings
for ARM platforms. Bindings define idle state parameters inclusive of entry
methods and state latencies, to allow operating systems to retrieve the
configuration entries from the device tree and initialize the related power
management drivers, paving the way for common code in the kernel to deal with
idle states and removing the need for static data in current and previous
kernel versions.
ARM64 platforms require the DT to define an entry-method property
for idle states.
On system implementing PSCI as an enable-method to enter low-power
states the PSCI CPU suspend method requires the power_state parameter to
be passed to the PSCI CPU suspend function.
This parameter is specific to a power state and platform specific,
therefore must be provided by firmware to the OS in order to enable
proper call sequence.
Thus, this patch also adds a property in the PSCI bindings that
describes how the PSCI CPU suspend power_state parameter should be
defined in DT in all device nodes that rely on PSCI CPU suspend method usage.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Sebastian Capella <sebcape@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
Documentation/devicetree/bindings/arm/cpus.txt | 8 +
.../devicetree/bindings/arm/idle-states.txt | 679 +++++++++++++++++++++
Documentation/devicetree/bindings/arm/psci.txt | 14 +-
3 files changed, 700 insertions(+), 1 deletion(-)
create mode 100644 Documentation/devicetree/bindings/arm/idle-states.txt
diff --git a/Documentation/devicetree/bindings/arm/cpus.txt b/Documentation/devicetree/bindings/arm/cpus.txt
index 298e2f6..6fd0f15 100644
--- a/Documentation/devicetree/bindings/arm/cpus.txt
+++ b/Documentation/devicetree/bindings/arm/cpus.txt
@@ -219,6 +219,12 @@ nodes to be present and contain the properties described below.
Value type: <phandle>
Definition: Specifies the ACC[2] node associated with this CPU.
+ - cpu-idle-states
+ Usage: Optional
+ Value type: <prop-encoded-array>
+ Definition:
+ # List of phandles to idle state nodes supported
+ by this cpu [3].
Example 1 (dual-cluster big.LITTLE system 32-bit):
@@ -415,3 +421,5 @@ cpus {
--
[1] arm/msm/qcom,saw2.txt
[2] arm/msm/qcom,kpss-acc.txt
+[3] ARM Linux kernel documentation - idle states bindings
+ Documentation/devicetree/bindings/arm/idle-states.txt
diff --git a/Documentation/devicetree/bindings/arm/idle-states.txt b/Documentation/devicetree/bindings/arm/idle-states.txt
new file mode 100644
index 0000000..37375c7
--- /dev/null
+++ b/Documentation/devicetree/bindings/arm/idle-states.txt
@@ -0,0 +1,679 @@
+==========================================
+ARM idle states binding description
+==========================================
+
+==========================================
+1 - Introduction
+==========================================
+
+ARM systems contain HW capable of managing power consumption dynamically,
+where cores can be put in different low-power states (ranging from simple
+wfi to power gating) according to OS PM policies. The CPU states representing
+the range of dynamic idle states that a processor can enter at run-time, can be
+specified through device tree bindings representing the parameters required
+to enter/exit specific idle states on a given processor.
+
+According to the Server Base System Architecture document (SBSA, [3]), the
+power states an ARM CPU can be put into are identified by the following list:
+
+- Running
+- Idle_standby
+- Idle_retention
+- Sleep
+- Off
+
+The power states described in the SBSA document define the basic CPU states on
+top of which ARM platforms implement power management schemes that allow an OS
+PM implementation to put the processor in different idle states (which include
+states listed above; "off" state is not an idle state since it does not have
+wake-up capabilities, hence it is not considered in this document).
+
+Idle state parameters (eg entry latency) are platform specific and need to be
+characterized with bindings that provide the required information to OS PM
+code so that it can build the required tables and use them at runtime.
+
+The device tree binding definition for ARM idle states is the subject of this
+document.
+
+===========================================
+2 - idle-states definitions
+===========================================
+
+Idle states are characterized for a specific system through a set of
+timing and energy related properties, that underline the HW behaviour
+triggered upon idle states entry and exit.
+
+The following diagram depicts the CPU execution phases and related timing
+properties required to enter and exit an idle state:
+
+..__[EXEC]__|__[PREP]__|__[ENTRY]__|__[IDLE]__|__[EXIT]__|__[EXEC]__..
+ | | | | |
+
+ |<------ entry ------->|
+ | latency |
+ |<- exit ->|
+ | latency |
+ |<-------- min-residency -------->|
+ |<------- wakeup-latency ------->|
+
+ Diagram 1: CPU idle state execution phases
+
+EXEC: Normal CPU execution.
+
+PREP: Preparation phase before committing the hardware to idle mode
+ like cache flushing. This is abortable on pending wake-up
+ event conditions. The abort latency is assumed to be negligible
+ (i.e. less than the ENTRY + EXIT duration). If aborted, CPU
+ goes back to EXEC. This phase is optional. If not abortable,
+ this should be included in the ENTRY phase instead.
+
+ENTRY: The hardware is committed to idle mode. This period must run
+ to completion up to IDLE before anything else can happen.
+
+IDLE: This is the actual energy-saving idle period. This may last
+ between 0 and infinite time, until a wake-up event occurs.
+
+EXIT: Period during which the CPU is brought back to operational
+ mode (EXEC).
+
+entry-latency: Worst case latency required to enter the idle state. The
+exit-latency may be guaranteed only after entry-latency has passed.
+
+min-residency: Minimum period, including preparation and entry, for a given
+idle state to be worthwhile energywise.
+
+wakeup-latency: Maximum delay between the signaling of a wake-up event and the
+CPU being able to execute normal code again. If not specified, this is assumed
+to be entry-latency + exit-latency.
+
+These timing parameters can be used by an OS in different circumstances.
+
+An idle CPU requires the expected min-residency time to select the most
+appropriate idle state based on the expected expiry time of the next IRQ
+(ie wake-up) that causes the CPU to return to the EXEC phase.
+
+An operating system scheduler may need to compute the shortest wake-up delay
+for CPUs in the system by detecting how long will it take to get a CPU out
+of an idle state, eg:
+
+wakeup-delay = exit-latency + max(entry-latency - (now - entry-timestamp), 0)
+
+In other words, the scheduler can make its scheduling decision by selecting
+(eg waking-up) the CPU with the shortest wake-up latency.
+The wake-up latency must take into account the entry latency if that period
+has not expired. The abortable nature of the PREP period can be ignored
+if it cannot be relied upon (e.g. the PREP deadline may occur much sooner than
+the worst case since it depends on the CPU operating conditions, ie caches
+state).
+
+An OS has to reliably probe the wakeup-latency since some devices can enforce
+latency constraints guarantees to work properly, so the OS has to detect the
+worst case wake-up latency it can incur if a CPU is allowed to enter an
+idle state, and possibly to prevent that to guarantee reliable device
+functioning.
+
+The min-residency time parameter deserves further explanation since it is
+expressed in time units but must factor in energy consumption coefficients.
+
+The energy consumption of a cpu when it enters a power state can be roughly
+characterised by the following graph:
+
+ |
+ |
+ |
+ e |
+ n | /---
+ e | /------
+ r | /------
+ g | /-----
+ y | /------
+ | ----
+ | /|
+ | / |
+ | / |
+ | / |
+ | / |
+ | / |
+ |/ |
+ -----|-------+----------------------------------
+ 0| 1 time(ms)
+
+ Graph 1: Energy vs time example
+
+The graph is split in two parts delimited by time 1ms on the X-axis.
+The graph curve with X-axis values = { x | 0 < x < 1ms } has a steep slope
+and denotes the energy costs incurred whilst entering and leaving the idle
+state.
+The graph curve in the area delimited by X-axis values = {x | x > 1ms } has
+shallower slope and essentially represents the energy consumption of the idle
+state.
+
+min-residency is defined for a given idle state as the minimum expected
+residency time for a state (inclusive of preparation and entry) after
+which choosing that state become the most energy efficient option. A good
+way to visualise this, is by taking the same graph above and comparing some
+states energy consumptions plots.
+
+For sake of simplicity, let's consider a system with two idle states IDLE1,
+and IDLE2:
+
+ |
+ |
+ |
+ | /-- IDLE1
+ e | /---
+ n | /----
+ e | /---
+ r | /-----/--------- IDLE2
+ g | /-------/---------
+ y | ------------ /---|
+ | / /---- |
+ | / /--- |
+ | / /---- |
+ | / /--- |
+ | --- |
+ | / |
+ | / |
+ |/ | time
+ ---/----------------------------+------------------------
+ |IDLE1-energy < IDLE2-energy | IDLE2-energy < IDLE1-energy
+ |
+ IDLE2-min-residency
+
+ Graph 2: idle states min-residency example
+
+In graph 2 above, that takes into account idle states entry/exit energy
+costs, it is clear that if the idle state residency time (ie time till next
+wake-up IRQ) is less than IDLE2-min-residency, IDLE1 is the better idle state
+choice energywise.
+
+This is mainly down to the fact that IDLE1 entry/exit energy costs are lower
+than IDLE2.
+
+However, the lower power consumption (ie shallower energy curve slope) of idle
+state IDLE2 implies that after a suitable time, IDLE2 becomes more energy
+efficient.
+
+The time@which IDLE2 becomes more energy efficient than IDLE1 (and other
+shallower states in a system with multiple idle states) is defined
+IDLE2-min-residency and corresponds to the time when energy consumption of
+IDLE1 and IDLE2 states breaks even.
+
+The definitions provided in this section underpin the idle states
+properties specification that is the subject of the following sections.
+
+===========================================
+3 - idle-states node
+===========================================
+
+ARM processor idle states are defined within the idle-states node, which is
+a direct child of the cpus node [1] and provides a container where the
+processor idle states, defined as device tree nodes, are listed.
+
+- idle-states node
+
+ Usage: Optional - On ARM systems, it is a container of processor idle
+ states nodes. If the system does not provide CPU
+ power management capabilities or the processor just
+ supports idle_standby an idle-states node is not
+ required.
+
+ Description: idle-states node is a container node, where its
+ subnodes describe the CPU idle states.
+
+ Node name must be "idle-states".
+
+ The idle-states node's parent node must be the cpus node.
+
+ The idle-states node's child nodes can be:
+
+ - one or more state nodes
+
+ Any other configuration is considered invalid.
+
+ An idle-states node defines the following properties:
+
+ - entry-method
+ Value type: <stringlist>
+ Usage and definition depend on ARM architecture version.
+ # On ARM v8 64-bit this property is required and must
+ be one of:
+ - "psci" (see bindings in [2])
+ # On ARM 32-bit systems this property is optional
+
+The nodes describing the idle states (state) can only be defined within the
+idle-states node, any other configuration is considered invalid and therefore
+must be ignored.
+
+===========================================
+4 - state node
+===========================================
+
+A state node represents an idle state description and must be defined as
+follows:
+
+- state node
+
+ Description: must be child of the idle-states node
+
+ The state node name shall follow standard device tree naming
+ rules ([5], 2.2.1 "Node names"), in particular state nodes which
+ are siblings within a single common parent must be given a unique name.
+
+ The idle state entered by executing the wfi instruction (idle_standby
+ SBSA,[3][4]) is considered standard on all ARM platforms and therefore
+ must not be listed.
+
+ With the definitions provided above, the following list represents
+ the valid properties for a state node:
+
+ - compatible
+ Usage: Required
+ Value type: <stringlist>
+ Definition: Must be "arm,idle-state".
+
+ - local-timer-stop
+ Usage: See definition
+ Value type: <none>
+ Definition: if present the CPU local timer control logic is
+ lost on state entry, otherwise it is retained.
+
+ - entry-latency-us
+ Usage: Required
+ Value type: <prop-encoded-array>
+ Definition: u32 value representing worst case latency in
+ microseconds required to enter the idle state.
+ The exit-latency-us duration may be guaranteed
+ only after entry-latency-us has passed.
+
+ - exit-latency-us
+ Usage: Required
+ Value type: <prop-encoded-array>
+ Definition: u32 value representing worst case latency
+ in microseconds required to exit the idle state.
+
+ - min-residency-us
+ Usage: Required
+ Value type: <prop-encoded-array>
+ Definition: u32 value representing minimum residency duration
+ in microseconds, inclusive of preparation and
+ entry, for this idle state to be considered
+ worthwhile energy wise (refer to section 2 of
+ this document for a complete description).
+
+ - wakeup-latency-us:
+ Usage: Optional
+ Value type: <prop-encoded-array>
+ Definition: u32 value representing maximum delay between the
+ signaling of a wake-up event and the CPU being
+ able to execute normal code again. If omitted,
+ this is assumed to be equal to:
+
+ entry-latency-us + exit-latency-us
+
+ It is important to supply this value on systems
+ where the duration of PREP phase (see diagram 1,
+ section 2) is non-neglibigle.
+ In such systems entry-latency-us + exit-latency-us
+ will exceed wakeup-latency-us by this duration.
+
+ In addition to the properties listed above, a state node may require
+ additional properties specifics to the entry-method defined in the
+ idle-states node, please refer to the entry-method bindings
+ documentation for properties definitions.
+
+===========================================
+4 - Examples
+===========================================
+
+Example 1 (ARM 64-bit, 16-cpu system, PSCI enable-method):
+
+cpus {
+ #size-cells = <0>;
+ #address-cells = <2>;
+
+ CPU0: cpu at 0 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a57";
+ reg = <0x0 0x0>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_0_0 &CPU_SLEEP_0_0
+ &CLUSTER_RETENTION_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU1: cpu at 1 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a57";
+ reg = <0x0 0x1>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_0_0 &CPU_SLEEP_0_0
+ &CLUSTER_RETENTION_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU2: cpu at 100 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a57";
+ reg = <0x0 0x100>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_0_0 &CPU_SLEEP_0_0
+ &CLUSTER_RETENTION_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU3: cpu at 101 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a57";
+ reg = <0x0 0x101>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_0_0 &CPU_SLEEP_0_0
+ &CLUSTER_RETENTION_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU4: cpu at 10000 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a57";
+ reg = <0x0 0x10000>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_0_0 &CPU_SLEEP_0_0
+ &CLUSTER_RETENTION_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU5: cpu at 10001 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a57";
+ reg = <0x0 0x10001>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_0_0 &CPU_SLEEP_0_0
+ &CLUSTER_RETENTION_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU6: cpu at 10100 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a57";
+ reg = <0x0 0x10100>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_0_0 &CPU_SLEEP_0_0
+ &CLUSTER_RETENTION_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU7: cpu at 10101 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a57";
+ reg = <0x0 0x10101>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_0_0 &CPU_SLEEP_0_0
+ &CLUSTER_RETENTION_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU8: cpu at 100000000 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a53";
+ reg = <0x1 0x0>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_1_0 &CPU_SLEEP_1_0
+ &CLUSTER_RETENTION_1 &CLUSTER_SLEEP_1>;
+ };
+
+ CPU9: cpu at 100000001 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a53";
+ reg = <0x1 0x1>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_1_0 &CPU_SLEEP_1_0
+ &CLUSTER_RETENTION_1 &CLUSTER_SLEEP_1>;
+ };
+
+ CPU10: cpu at 100000100 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a53";
+ reg = <0x1 0x100>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_1_0 &CPU_SLEEP_1_0
+ &CLUSTER_RETENTION_1 &CLUSTER_SLEEP_1>;
+ };
+
+ CPU11: cpu at 100000101 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a53";
+ reg = <0x1 0x101>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_1_0 &CPU_SLEEP_1_0
+ &CLUSTER_RETENTION_1 &CLUSTER_SLEEP_1>;
+ };
+
+ CPU12: cpu at 100010000 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a53";
+ reg = <0x1 0x10000>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_1_0 &CPU_SLEEP_1_0
+ &CLUSTER_RETENTION_1 &CLUSTER_SLEEP_1>;
+ };
+
+ CPU13: cpu at 100010001 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a53";
+ reg = <0x1 0x10001>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_1_0 &CPU_SLEEP_1_0
+ &CLUSTER_RETENTION_1 &CLUSTER_SLEEP_1>;
+ };
+
+ CPU14: cpu at 100010100 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a53";
+ reg = <0x1 0x10100>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_1_0 &CPU_SLEEP_1_0
+ &CLUSTER_RETENTION_1 &CLUSTER_SLEEP_1>;
+ };
+
+ CPU15: cpu at 100010101 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a53";
+ reg = <0x1 0x10101>;
+ enable-method = "psci";
+ cpu-idle-states = <&CPU_RETENTION_1_0 &CPU_SLEEP_1_0
+ &CLUSTER_RETENTION_1 &CLUSTER_SLEEP_1>;
+ };
+
+ idle-states {
+ entry-method = "arm,psci";
+
+ CPU_RETENTION_0_0: cpu-retention-0-0 {
+ compatible = "arm,idle-state";
+ arm,psci-suspend-param = <0x0010000>;
+ entry-latency-us = <20>;
+ exit-latency-us = <40>;
+ min-residency-us = <80>;
+ };
+
+ CLUSTER_RETENTION_0: cluster-retention-0 {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ arm,psci-suspend-param = <0x1010000>;
+ entry-latency-us = <50>;
+ exit-latency-us = <100>;
+ min-residency-us = <250>;
+ wakeup-latency-us = <130>;
+ };
+
+ CPU_SLEEP_0_0: cpu-sleep-0-0 {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ arm,psci-suspend-param = <0x0010000>;
+ entry-latency-us = <250>;
+ exit-latency-us = <500>;
+ min-residency-us = <950>;
+ };
+
+ CLUSTER_SLEEP_0: cluster-sleep-0 {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ arm,psci-suspend-param = <0x1010000>;
+ entry-latency-us = <600>;
+ exit-latency-us = <1100>;
+ min-residency-us = <2700>;
+ wakeup-latency-us = <1500>;
+ };
+
+ CPU_RETENTION_1_0: cpu-retention-1-0 {
+ compatible = "arm,idle-state";
+ arm,psci-suspend-param = <0x0010000>;
+ entry-latency-us = <20>;
+ exit-latency-us = <40>;
+ min-residency-us = <90>;
+ };
+
+ CLUSTER_RETENTION_1: cluster-retention-1 {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ arm,psci-suspend-param = <0x1010000>;
+ entry-latency-us = <50>;
+ exit-latency-us = <100>;
+ min-residency-us = <270>;
+ wakeup-latency-us = <100>;
+ };
+
+ CPU_SLEEP_1_0: cpu-sleep-1-0 {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ arm,psci-suspend-param = <0x0010000>;
+ entry-latency-us = <70>;
+ exit-latency-us = <100>;
+ min-residency-us = <300>;
+ wakeup-latency-us = <150>;
+ };
+
+ CLUSTER_SLEEP_1: cluster-sleep-1 {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ arm,psci-suspend-param = <0x1010000>;
+ entry-latency-us = <500>;
+ exit-latency-us = <1200>;
+ min-residency-us = <3500>;
+ wakeup-latency-us = <1300>;
+ };
+ };
+
+};
+
+Example 2 (ARM 32-bit, 8-cpu system, two clusters):
+
+cpus {
+ #size-cells = <0>;
+ #address-cells = <1>;
+
+ CPU0: cpu at 0 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a15";
+ reg = <0x0>;
+ cpu-idle-states = <&CPU_SLEEP_0_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU1: cpu at 1 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a15";
+ reg = <0x1>;
+ cpu-idle-states = <&CPU_SLEEP_0_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU2: cpu at 2 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a15";
+ reg = <0x2>;
+ cpu-idle-states = <&CPU_SLEEP_0_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU3: cpu at 3 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a15";
+ reg = <0x3>;
+ cpu-idle-states = <&CPU_SLEEP_0_0 &CLUSTER_SLEEP_0>;
+ };
+
+ CPU4: cpu at 100 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a7";
+ reg = <0x100>;
+ cpu-idle-states = <&CPU_SLEEP_1_0 &CLUSTER_SLEEP_1>;
+ };
+
+ CPU5: cpu at 101 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a7";
+ reg = <0x101>;
+ cpu-idle-states = <&CPU_SLEEP_1_0 &CLUSTER_SLEEP_1>;
+ };
+
+ CPU6: cpu at 102 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a7";
+ reg = <0x102>;
+ cpu-idle-states = <&CPU_SLEEP_1_0 &CLUSTER_SLEEP_1>;
+ };
+
+ CPU7: cpu at 103 {
+ device_type = "cpu";
+ compatible = "arm,cortex-a7";
+ reg = <0x103>;
+ cpu-idle-states = <&CPU_SLEEP_1_0 &CLUSTER_SLEEP_1>;
+ };
+
+ idle-states {
+ CPU_SLEEP_0_0: cpu-sleep-0-0 {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ entry-latency-us = <200>;
+ exit-latency-us = <100>;
+ min-residency-us = <400>;
+ wakeup-latency-us = <250>;
+ };
+
+ CLUSTER_SLEEP_0: cluster-sleep-0 {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ entry-latency-us = <500>;
+ exit-latency-us = <1500>;
+ min-residency-us = <2500>;
+ wakeup-latency-us = <1700>;
+ };
+
+ CPU_SLEEP_1_0: cpu-sleep-1-0 {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ entry-latency-us = <300>;
+ exit-latency-us = <500>;
+ min-residency-us = <900>;
+ wakeup-latency-us = <600>;
+ };
+
+ CLUSTER_SLEEP_1: cluster-sleep-1 {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ entry-latency-us = <800>;
+ exit-latency-us = <2000>;
+ min-residency-us = <6500>;
+ wakeup-latency-us = <2300>;
+ };
+ };
+
+};
+
+===========================================
+5 - References
+===========================================
+
+[1] ARM Linux Kernel documentation - CPUs bindings
+ Documentation/devicetree/bindings/arm/cpus.txt
+
+[2] ARM Linux Kernel documentation - PSCI bindings
+ Documentation/devicetree/bindings/arm/psci.txt
+
+[3] ARM Server Base System Architecture (SBSA)
+ http://infocenter.arm.com/help/index.jsp
+
+[4] ARM Architecture Reference Manuals
+ http://infocenter.arm.com/help/index.jsp
+
+[5] ePAPR standard
+ https://www.power.org/documentation/epapr-version-1-1/
diff --git a/Documentation/devicetree/bindings/arm/psci.txt b/Documentation/devicetree/bindings/arm/psci.txt
index b4a58f3..5aa40ed 100644
--- a/Documentation/devicetree/bindings/arm/psci.txt
+++ b/Documentation/devicetree/bindings/arm/psci.txt
@@ -50,6 +50,16 @@ Main node optional properties:
- migrate : Function ID for MIGRATE operation
+Device tree nodes that require usage of PSCI CPU_SUSPEND function (ie idle
+state nodes, as per bindings in [1]) must specify the following properties:
+
+- arm,psci-suspend-param
+ Usage: Required for state nodes[1] if the corresponding
+ idle-states node entry-method property is set
+ to "psci".
+ Value type: <u32>
+ Definition: power_state parameter to pass to the PSCI
+ suspend call.
Example:
@@ -64,7 +74,6 @@ Case 1: PSCI v0.1 only.
migrate = <0x95c10003>;
};
-
Case 2: PSCI v0.2 only
psci {
@@ -88,3 +97,6 @@ Case 3: PSCI v0.2 and PSCI v0.1.
...
};
+
+[1] Kernel documentation - ARM idle states bindings
+ Documentation/devicetree/bindings/arm/idle-states.txt
--
1.9.1
^ permalink raw reply related [flat|nested] 29+ messages in thread
* [PATCH v9 2/8] arm64: kernel: refactor the CPU suspend API for retention states
2014-09-05 17:34 ` Lorenzo Pieralisi
@ 2014-09-05 17:34 ` Lorenzo Pieralisi
-1 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-05 17:34 UTC (permalink / raw)
To: linux-arm-kernel, linux-pm
Cc: devicetree, Lorenzo Pieralisi, Mark Rutland, Sudeep Holla,
Catalin Marinas, Will Deacon, Charles Garcia Tobin, Nicolas Pitre,
Rob Herring, Grant Likely, Peter De Schrijver, Santosh Shilimkar,
Daniel Lezcano, Amit Kucheria, Vincent Guittot, Antti Miettinen,
Stephen Boyd, Kevin Hilman, Sebastian Capella, Mark Brown,
Paul Walmsley, Chander Kashyap, Geoff
CPU suspend is the standard kernel interface to be used to enter
low-power states on ARM64 systems. Current cpu_suspend implementation
by default assumes that all low power states are losing the CPU context,
so the CPU registers must be saved and cleaned to DRAM upon state
entry. Furthermore, the current cpu_suspend() implementation assumes
that if the CPU suspend back-end method returns when called, this has
to be considered an error regardless of the return code (which can be
successful) since the CPU was not expected to return from a code path that
is different from cpu_resume code path - eg returning from the reset vector.
All in all this means that the current API does not cope well with low-power
states that preserve the CPU context when entered (ie retention states),
since first of all the context is saved for nothing on state entry for
those states and a successful state entry can return as a normal function
return, which is considered an error by the current CPU suspend
implementation.
This patch refactors the cpu_suspend() API so that it can be split in
two separate functionalities. The arm64 cpu_suspend API just provides
a wrapper around CPU suspend operation hook. A new function is
introduced (for architecture code use only) for states that require
context saving upon entry:
__cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
__cpu_suspend() saves the context on function entry and calls the
so called suspend finisher (ie fn) to complete the suspend operation.
The finisher is not expected to return, unless it fails in which case
the error is propagated back to the __cpu_suspend caller.
The API refactoring results in the following pseudo code call sequence for a
suspending CPU, when triggered from a kernel subsystem:
/*
* int cpu_suspend(unsigned long idx)
* @idx: idle state index
*/
{
-> cpu_suspend(idx)
|---> CPU operations suspend hook called, if present
|--> if (retention_state)
|--> direct suspend back-end call (eg PSCI suspend)
else
|--> __cpu_suspend(idx, &back_end_finisher);
}
By refactoring the cpu_suspend API this way, the CPU operations back-end
has a chance to detect whether idle states require state saving or not
and can call the required suspend operations accordingly either through
simple function call or indirectly through __cpu_suspend() which carries out
state saving and suspend finisher dispatching to complete idle state entry.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
arch/arm64/include/asm/suspend.h | 1 +
arch/arm64/kernel/sleep.S | 47 ++++++++++++++++++++++++++++-----------
arch/arm64/kernel/suspend.c | 48 ++++++++++++++++++++++++----------------
3 files changed, 64 insertions(+), 32 deletions(-)
diff --git a/arch/arm64/include/asm/suspend.h b/arch/arm64/include/asm/suspend.h
index e9c149c..456d67c 100644
--- a/arch/arm64/include/asm/suspend.h
+++ b/arch/arm64/include/asm/suspend.h
@@ -21,6 +21,7 @@ struct sleep_save_sp {
phys_addr_t save_ptr_stash_phys;
};
+extern int __cpu_suspend(unsigned long arg, int (*fn)(unsigned long));
extern void cpu_resume(void);
extern int cpu_suspend(unsigned long);
diff --git a/arch/arm64/kernel/sleep.S b/arch/arm64/kernel/sleep.S
index b192572..a564b44 100644
--- a/arch/arm64/kernel/sleep.S
+++ b/arch/arm64/kernel/sleep.S
@@ -49,28 +49,39 @@
orr \dst, \dst, \mask // dst|=(aff3>>rs3)
.endm
/*
- * Save CPU state for a suspend. This saves callee registers, and allocates
- * space on the kernel stack to save the CPU specific registers + some
- * other data for resume.
+ * Save CPU state for a suspend and execute the suspend finisher.
+ * On success it will return 0 through cpu_resume - ie through a CPU
+ * soft/hard reboot from the reset vector.
+ * On failure it returns the suspend finisher return value or force
+ * -EOPNOTSUPP if the finisher erroneously returns 0 (the suspend finisher
+ * is not allowed to return, if it does this must be considered failure).
+ * It saves callee registers, and allocates space on the kernel stack
+ * to save the CPU specific registers + some other data for resume.
*
* x0 = suspend finisher argument
+ * x1 = suspend finisher function pointer
*/
-ENTRY(__cpu_suspend)
+ENTRY(__cpu_suspend_enter)
stp x29, lr, [sp, #-96]!
stp x19, x20, [sp,#16]
stp x21, x22, [sp,#32]
stp x23, x24, [sp,#48]
stp x25, x26, [sp,#64]
stp x27, x28, [sp,#80]
+ /*
+ * Stash suspend finisher and its argument in x20 and x19
+ */
+ mov x19, x0
+ mov x20, x1
mov x2, sp
sub sp, sp, #CPU_SUSPEND_SZ // allocate cpu_suspend_ctx
- mov x1, sp
+ mov x0, sp
/*
- * x1 now points to struct cpu_suspend_ctx allocated on the stack
+ * x0 now points to struct cpu_suspend_ctx allocated on the stack
*/
- str x2, [x1, #CPU_CTX_SP]
- ldr x2, =sleep_save_sp
- ldr x2, [x2, #SLEEP_SAVE_SP_VIRT]
+ str x2, [x0, #CPU_CTX_SP]
+ ldr x1, =sleep_save_sp
+ ldr x1, [x1, #SLEEP_SAVE_SP_VIRT]
#ifdef CONFIG_SMP
mrs x7, mpidr_el1
ldr x9, =mpidr_hash
@@ -82,11 +93,21 @@ ENTRY(__cpu_suspend)
ldp w3, w4, [x9, #MPIDR_HASH_SHIFTS]
ldp w5, w6, [x9, #(MPIDR_HASH_SHIFTS + 8)]
compute_mpidr_hash x8, x3, x4, x5, x6, x7, x10
- add x2, x2, x8, lsl #3
+ add x1, x1, x8, lsl #3
#endif
- bl __cpu_suspend_finisher
+ bl __cpu_suspend_save
+ /*
+ * Grab suspend finisher in x20 and its argument in x19
+ */
+ mov x0, x19
+ mov x1, x20
+ /*
+ * We are ready for power down, fire off the suspend finisher
+ * in x1, with argument in x0
+ */
+ blr x1
/*
- * Never gets here, unless suspend fails.
+ * Never gets here, unless suspend finisher fails.
* Successful cpu_suspend should return from cpu_resume, returning
* through this code path is considered an error
* If the return value is set to 0 force x0 = -EOPNOTSUPP
@@ -103,7 +124,7 @@ ENTRY(__cpu_suspend)
ldp x27, x28, [sp, #80]
ldp x29, lr, [sp], #96
ret
-ENDPROC(__cpu_suspend)
+ENDPROC(__cpu_suspend_enter)
.ltorg
/*
diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c
index 55a99b9..13ad4db 100644
--- a/arch/arm64/kernel/suspend.c
+++ b/arch/arm64/kernel/suspend.c
@@ -9,22 +9,19 @@
#include <asm/suspend.h>
#include <asm/tlbflush.h>
-extern int __cpu_suspend(unsigned long);
+extern int __cpu_suspend_enter(unsigned long arg, int (*fn)(unsigned long));
/*
- * This is called by __cpu_suspend() to save the state, and do whatever
+ * This is called by __cpu_suspend_enter() to save the state, and do whatever
* flushing is required to ensure that when the CPU goes to sleep we have
* the necessary data available when the caches are not searched.
*
- * @arg: Argument to pass to suspend operations
- * @ptr: CPU context virtual address
- * @save_ptr: address of the location where the context physical address
- * must be saved
+ * ptr: CPU context virtual address
+ * save_ptr: address of the location where the context physical address
+ * must be saved
*/
-int __cpu_suspend_finisher(unsigned long arg, struct cpu_suspend_ctx *ptr,
- phys_addr_t *save_ptr)
+void notrace __cpu_suspend_save(struct cpu_suspend_ctx *ptr,
+ phys_addr_t *save_ptr)
{
- int cpu = smp_processor_id();
-
*save_ptr = virt_to_phys(ptr);
cpu_do_suspend(ptr);
@@ -35,8 +32,6 @@ int __cpu_suspend_finisher(unsigned long arg, struct cpu_suspend_ctx *ptr,
*/
__flush_dcache_area(ptr, sizeof(*ptr));
__flush_dcache_area(save_ptr, sizeof(*save_ptr));
-
- return cpu_ops[cpu]->cpu_suspend(arg);
}
/*
@@ -56,15 +51,15 @@ void __init cpu_suspend_set_dbg_restorer(void (*hw_bp_restore)(void *))
}
/**
- * cpu_suspend
+ * cpu_suspend() - function to enter a low-power state
+ * @arg: argument to pass to CPU suspend operations
*
- * @arg: argument to pass to the finisher function
+ * Return: 0 on success, -EOPNOTSUPP if CPU suspend hook not initialized, CPU
+ * operations back-end error code otherwise.
*/
int cpu_suspend(unsigned long arg)
{
- struct mm_struct *mm = current->active_mm;
- int ret, cpu = smp_processor_id();
- unsigned long flags;
+ int cpu = smp_processor_id();
/*
* If cpu_ops have not been registered or suspend
@@ -72,6 +67,21 @@ int cpu_suspend(unsigned long arg)
*/
if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_suspend)
return -EOPNOTSUPP;
+ return cpu_ops[cpu]->cpu_suspend(arg);
+}
+
+/*
+ * __cpu_suspend
+ *
+ * arg: argument to pass to the finisher function
+ * fn: finisher function pointer
+ *
+ */
+int __cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
+{
+ struct mm_struct *mm = current->active_mm;
+ int ret;
+ unsigned long flags;
/*
* From this point debug exceptions are disabled to prevent
@@ -86,7 +96,7 @@ int cpu_suspend(unsigned long arg)
* page tables, so that the thread address space is properly
* set-up on function return.
*/
- ret = __cpu_suspend(arg);
+ ret = __cpu_suspend_enter(arg, fn);
if (ret == 0) {
cpu_switch_mm(mm->pgd, mm);
flush_tlb_all();
@@ -95,7 +105,7 @@ int cpu_suspend(unsigned long arg)
* Restore per-cpu offset before any kernel
* subsystem relying on it has a chance to run.
*/
- set_my_cpu_offset(per_cpu_offset(cpu));
+ set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
/*
* Restore HW breakpoint registers to sane values
--
1.9.1
^ permalink raw reply related [flat|nested] 29+ messages in thread
* [PATCH v9 2/8] arm64: kernel: refactor the CPU suspend API for retention states
@ 2014-09-05 17:34 ` Lorenzo Pieralisi
0 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-05 17:34 UTC (permalink / raw)
To: linux-arm-kernel
CPU suspend is the standard kernel interface to be used to enter
low-power states on ARM64 systems. Current cpu_suspend implementation
by default assumes that all low power states are losing the CPU context,
so the CPU registers must be saved and cleaned to DRAM upon state
entry. Furthermore, the current cpu_suspend() implementation assumes
that if the CPU suspend back-end method returns when called, this has
to be considered an error regardless of the return code (which can be
successful) since the CPU was not expected to return from a code path that
is different from cpu_resume code path - eg returning from the reset vector.
All in all this means that the current API does not cope well with low-power
states that preserve the CPU context when entered (ie retention states),
since first of all the context is saved for nothing on state entry for
those states and a successful state entry can return as a normal function
return, which is considered an error by the current CPU suspend
implementation.
This patch refactors the cpu_suspend() API so that it can be split in
two separate functionalities. The arm64 cpu_suspend API just provides
a wrapper around CPU suspend operation hook. A new function is
introduced (for architecture code use only) for states that require
context saving upon entry:
__cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
__cpu_suspend() saves the context on function entry and calls the
so called suspend finisher (ie fn) to complete the suspend operation.
The finisher is not expected to return, unless it fails in which case
the error is propagated back to the __cpu_suspend caller.
The API refactoring results in the following pseudo code call sequence for a
suspending CPU, when triggered from a kernel subsystem:
/*
* int cpu_suspend(unsigned long idx)
* @idx: idle state index
*/
{
-> cpu_suspend(idx)
|---> CPU operations suspend hook called, if present
|--> if (retention_state)
|--> direct suspend back-end call (eg PSCI suspend)
else
|--> __cpu_suspend(idx, &back_end_finisher);
}
By refactoring the cpu_suspend API this way, the CPU operations back-end
has a chance to detect whether idle states require state saving or not
and can call the required suspend operations accordingly either through
simple function call or indirectly through __cpu_suspend() which carries out
state saving and suspend finisher dispatching to complete idle state entry.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
arch/arm64/include/asm/suspend.h | 1 +
arch/arm64/kernel/sleep.S | 47 ++++++++++++++++++++++++++++-----------
arch/arm64/kernel/suspend.c | 48 ++++++++++++++++++++++++----------------
3 files changed, 64 insertions(+), 32 deletions(-)
diff --git a/arch/arm64/include/asm/suspend.h b/arch/arm64/include/asm/suspend.h
index e9c149c..456d67c 100644
--- a/arch/arm64/include/asm/suspend.h
+++ b/arch/arm64/include/asm/suspend.h
@@ -21,6 +21,7 @@ struct sleep_save_sp {
phys_addr_t save_ptr_stash_phys;
};
+extern int __cpu_suspend(unsigned long arg, int (*fn)(unsigned long));
extern void cpu_resume(void);
extern int cpu_suspend(unsigned long);
diff --git a/arch/arm64/kernel/sleep.S b/arch/arm64/kernel/sleep.S
index b192572..a564b44 100644
--- a/arch/arm64/kernel/sleep.S
+++ b/arch/arm64/kernel/sleep.S
@@ -49,28 +49,39 @@
orr \dst, \dst, \mask // dst|=(aff3>>rs3)
.endm
/*
- * Save CPU state for a suspend. This saves callee registers, and allocates
- * space on the kernel stack to save the CPU specific registers + some
- * other data for resume.
+ * Save CPU state for a suspend and execute the suspend finisher.
+ * On success it will return 0 through cpu_resume - ie through a CPU
+ * soft/hard reboot from the reset vector.
+ * On failure it returns the suspend finisher return value or force
+ * -EOPNOTSUPP if the finisher erroneously returns 0 (the suspend finisher
+ * is not allowed to return, if it does this must be considered failure).
+ * It saves callee registers, and allocates space on the kernel stack
+ * to save the CPU specific registers + some other data for resume.
*
* x0 = suspend finisher argument
+ * x1 = suspend finisher function pointer
*/
-ENTRY(__cpu_suspend)
+ENTRY(__cpu_suspend_enter)
stp x29, lr, [sp, #-96]!
stp x19, x20, [sp,#16]
stp x21, x22, [sp,#32]
stp x23, x24, [sp,#48]
stp x25, x26, [sp,#64]
stp x27, x28, [sp,#80]
+ /*
+ * Stash suspend finisher and its argument in x20 and x19
+ */
+ mov x19, x0
+ mov x20, x1
mov x2, sp
sub sp, sp, #CPU_SUSPEND_SZ // allocate cpu_suspend_ctx
- mov x1, sp
+ mov x0, sp
/*
- * x1 now points to struct cpu_suspend_ctx allocated on the stack
+ * x0 now points to struct cpu_suspend_ctx allocated on the stack
*/
- str x2, [x1, #CPU_CTX_SP]
- ldr x2, =sleep_save_sp
- ldr x2, [x2, #SLEEP_SAVE_SP_VIRT]
+ str x2, [x0, #CPU_CTX_SP]
+ ldr x1, =sleep_save_sp
+ ldr x1, [x1, #SLEEP_SAVE_SP_VIRT]
#ifdef CONFIG_SMP
mrs x7, mpidr_el1
ldr x9, =mpidr_hash
@@ -82,11 +93,21 @@ ENTRY(__cpu_suspend)
ldp w3, w4, [x9, #MPIDR_HASH_SHIFTS]
ldp w5, w6, [x9, #(MPIDR_HASH_SHIFTS + 8)]
compute_mpidr_hash x8, x3, x4, x5, x6, x7, x10
- add x2, x2, x8, lsl #3
+ add x1, x1, x8, lsl #3
#endif
- bl __cpu_suspend_finisher
+ bl __cpu_suspend_save
+ /*
+ * Grab suspend finisher in x20 and its argument in x19
+ */
+ mov x0, x19
+ mov x1, x20
+ /*
+ * We are ready for power down, fire off the suspend finisher
+ * in x1, with argument in x0
+ */
+ blr x1
/*
- * Never gets here, unless suspend fails.
+ * Never gets here, unless suspend finisher fails.
* Successful cpu_suspend should return from cpu_resume, returning
* through this code path is considered an error
* If the return value is set to 0 force x0 = -EOPNOTSUPP
@@ -103,7 +124,7 @@ ENTRY(__cpu_suspend)
ldp x27, x28, [sp, #80]
ldp x29, lr, [sp], #96
ret
-ENDPROC(__cpu_suspend)
+ENDPROC(__cpu_suspend_enter)
.ltorg
/*
diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c
index 55a99b9..13ad4db 100644
--- a/arch/arm64/kernel/suspend.c
+++ b/arch/arm64/kernel/suspend.c
@@ -9,22 +9,19 @@
#include <asm/suspend.h>
#include <asm/tlbflush.h>
-extern int __cpu_suspend(unsigned long);
+extern int __cpu_suspend_enter(unsigned long arg, int (*fn)(unsigned long));
/*
- * This is called by __cpu_suspend() to save the state, and do whatever
+ * This is called by __cpu_suspend_enter() to save the state, and do whatever
* flushing is required to ensure that when the CPU goes to sleep we have
* the necessary data available when the caches are not searched.
*
- * @arg: Argument to pass to suspend operations
- * @ptr: CPU context virtual address
- * @save_ptr: address of the location where the context physical address
- * must be saved
+ * ptr: CPU context virtual address
+ * save_ptr: address of the location where the context physical address
+ * must be saved
*/
-int __cpu_suspend_finisher(unsigned long arg, struct cpu_suspend_ctx *ptr,
- phys_addr_t *save_ptr)
+void notrace __cpu_suspend_save(struct cpu_suspend_ctx *ptr,
+ phys_addr_t *save_ptr)
{
- int cpu = smp_processor_id();
-
*save_ptr = virt_to_phys(ptr);
cpu_do_suspend(ptr);
@@ -35,8 +32,6 @@ int __cpu_suspend_finisher(unsigned long arg, struct cpu_suspend_ctx *ptr,
*/
__flush_dcache_area(ptr, sizeof(*ptr));
__flush_dcache_area(save_ptr, sizeof(*save_ptr));
-
- return cpu_ops[cpu]->cpu_suspend(arg);
}
/*
@@ -56,15 +51,15 @@ void __init cpu_suspend_set_dbg_restorer(void (*hw_bp_restore)(void *))
}
/**
- * cpu_suspend
+ * cpu_suspend() - function to enter a low-power state
+ * @arg: argument to pass to CPU suspend operations
*
- * @arg: argument to pass to the finisher function
+ * Return: 0 on success, -EOPNOTSUPP if CPU suspend hook not initialized, CPU
+ * operations back-end error code otherwise.
*/
int cpu_suspend(unsigned long arg)
{
- struct mm_struct *mm = current->active_mm;
- int ret, cpu = smp_processor_id();
- unsigned long flags;
+ int cpu = smp_processor_id();
/*
* If cpu_ops have not been registered or suspend
@@ -72,6 +67,21 @@ int cpu_suspend(unsigned long arg)
*/
if (!cpu_ops[cpu] || !cpu_ops[cpu]->cpu_suspend)
return -EOPNOTSUPP;
+ return cpu_ops[cpu]->cpu_suspend(arg);
+}
+
+/*
+ * __cpu_suspend
+ *
+ * arg: argument to pass to the finisher function
+ * fn: finisher function pointer
+ *
+ */
+int __cpu_suspend(unsigned long arg, int (*fn)(unsigned long))
+{
+ struct mm_struct *mm = current->active_mm;
+ int ret;
+ unsigned long flags;
/*
* From this point debug exceptions are disabled to prevent
@@ -86,7 +96,7 @@ int cpu_suspend(unsigned long arg)
* page tables, so that the thread address space is properly
* set-up on function return.
*/
- ret = __cpu_suspend(arg);
+ ret = __cpu_suspend_enter(arg, fn);
if (ret == 0) {
cpu_switch_mm(mm->pgd, mm);
flush_tlb_all();
@@ -95,7 +105,7 @@ int cpu_suspend(unsigned long arg)
* Restore per-cpu offset before any kernel
* subsystem relying on it has a chance to run.
*/
- set_my_cpu_offset(per_cpu_offset(cpu));
+ set_my_cpu_offset(per_cpu_offset(smp_processor_id()));
/*
* Restore HW breakpoint registers to sane values
--
1.9.1
^ permalink raw reply related [flat|nested] 29+ messages in thread
* [PATCH v9 3/8] arm64: kernel: introduce cpu_init_idle CPU operation
2014-09-05 17:34 ` Lorenzo Pieralisi
@ 2014-09-05 17:34 ` Lorenzo Pieralisi
-1 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-05 17:34 UTC (permalink / raw)
To: linux-arm-kernel, linux-pm
Cc: devicetree, Lorenzo Pieralisi, Mark Rutland, Sudeep Holla,
Catalin Marinas, Will Deacon, Charles Garcia Tobin, Nicolas Pitre,
Rob Herring, Grant Likely, Peter De Schrijver, Santosh Shilimkar,
Daniel Lezcano, Amit Kucheria, Vincent Guittot, Antti Miettinen,
Stephen Boyd, Kevin Hilman, Sebastian Capella, Mark Brown,
Paul Walmsley, Chander Kashyap, Geoff
The CPUidle subsystem on ARM64 machines requires the idle states
implementation back-end to initialize idle states parameter upon
boot. This patch adds a hook in the CPU operations structure that
should be initialized by the CPU operations back-end in order to
provide a function that initializes cpu idle states.
This patch also adds the infrastructure to arm64 kernel required
to export the CPU operations based initialization interface, so
that drivers (ie CPUidle) can use it when they are initialized
at probe time.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
arch/arm64/include/asm/cpu_ops.h | 3 +++
arch/arm64/include/asm/cpuidle.h | 13 +++++++++++++
arch/arm64/kernel/Makefile | 1 +
arch/arm64/kernel/cpuidle.c | 31 +++++++++++++++++++++++++++++++
4 files changed, 48 insertions(+)
create mode 100644 arch/arm64/include/asm/cpuidle.h
create mode 100644 arch/arm64/kernel/cpuidle.c
diff --git a/arch/arm64/include/asm/cpu_ops.h b/arch/arm64/include/asm/cpu_ops.h
index d7b4b38..47dfa31 100644
--- a/arch/arm64/include/asm/cpu_ops.h
+++ b/arch/arm64/include/asm/cpu_ops.h
@@ -28,6 +28,8 @@ struct device_node;
* enable-method property.
* @cpu_init: Reads any data necessary for a specific enable-method from the
* devicetree, for a given cpu node and proposed logical id.
+ * @cpu_init_idle: Reads any data necessary to initialize CPU idle states from
+ * devicetree, for a given cpu node and proposed logical id.
* @cpu_prepare: Early one-time preparation step for a cpu. If there is a
* mechanism for doing so, tests whether it is possible to boot
* the given CPU.
@@ -47,6 +49,7 @@ struct device_node;
struct cpu_operations {
const char *name;
int (*cpu_init)(struct device_node *, unsigned int);
+ int (*cpu_init_idle)(struct device_node *, unsigned int);
int (*cpu_prepare)(unsigned int);
int (*cpu_boot)(unsigned int);
void (*cpu_postboot)(void);
diff --git a/arch/arm64/include/asm/cpuidle.h b/arch/arm64/include/asm/cpuidle.h
new file mode 100644
index 0000000..b52a993
--- /dev/null
+++ b/arch/arm64/include/asm/cpuidle.h
@@ -0,0 +1,13 @@
+#ifndef __ASM_CPUIDLE_H
+#define __ASM_CPUIDLE_H
+
+#ifdef CONFIG_CPU_IDLE
+extern int cpu_init_idle(unsigned int cpu);
+#else
+static inline int cpu_init_idle(unsigned int cpu)
+{
+ return -EOPNOTSUPP;
+}
+#endif
+
+#endif
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 383d81d..be78980 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -27,6 +27,7 @@ arm64-obj-$(CONFIG_PERF_EVENTS) += perf_regs.o
arm64-obj-$(CONFIG_HW_PERF_EVENTS) += perf_event.o
arm64-obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
arm64-obj-$(CONFIG_ARM64_CPU_SUSPEND) += sleep.o suspend.o
+arm64-obj-$(CONFIG_CPU_IDLE) += cpuidle.o
arm64-obj-$(CONFIG_JUMP_LABEL) += jump_label.o
arm64-obj-$(CONFIG_KGDB) += kgdb.o
arm64-obj-$(CONFIG_EFI) += efi.o efi-stub.o efi-entry.o
diff --git a/arch/arm64/kernel/cpuidle.c b/arch/arm64/kernel/cpuidle.c
new file mode 100644
index 0000000..19d17f5
--- /dev/null
+++ b/arch/arm64/kernel/cpuidle.c
@@ -0,0 +1,31 @@
+/*
+ * ARM64 CPU idle arch support
+ *
+ * Copyright (C) 2014 ARM Ltd.
+ * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+#include <asm/cpuidle.h>
+#include <asm/cpu_ops.h>
+
+int cpu_init_idle(unsigned int cpu)
+{
+ int ret = -EOPNOTSUPP;
+ struct device_node *cpu_node = of_cpu_device_node_get(cpu);
+
+ if (!cpu_node)
+ return -ENODEV;
+
+ if (cpu_ops[cpu] && cpu_ops[cpu]->cpu_init_idle)
+ ret = cpu_ops[cpu]->cpu_init_idle(cpu_node, cpu);
+
+ of_node_put(cpu_node);
+ return ret;
+}
--
1.9.1
^ permalink raw reply related [flat|nested] 29+ messages in thread
* [PATCH v9 3/8] arm64: kernel: introduce cpu_init_idle CPU operation
@ 2014-09-05 17:34 ` Lorenzo Pieralisi
0 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-05 17:34 UTC (permalink / raw)
To: linux-arm-kernel
The CPUidle subsystem on ARM64 machines requires the idle states
implementation back-end to initialize idle states parameter upon
boot. This patch adds a hook in the CPU operations structure that
should be initialized by the CPU operations back-end in order to
provide a function that initializes cpu idle states.
This patch also adds the infrastructure to arm64 kernel required
to export the CPU operations based initialization interface, so
that drivers (ie CPUidle) can use it when they are initialized
at probe time.
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
arch/arm64/include/asm/cpu_ops.h | 3 +++
arch/arm64/include/asm/cpuidle.h | 13 +++++++++++++
arch/arm64/kernel/Makefile | 1 +
arch/arm64/kernel/cpuidle.c | 31 +++++++++++++++++++++++++++++++
4 files changed, 48 insertions(+)
create mode 100644 arch/arm64/include/asm/cpuidle.h
create mode 100644 arch/arm64/kernel/cpuidle.c
diff --git a/arch/arm64/include/asm/cpu_ops.h b/arch/arm64/include/asm/cpu_ops.h
index d7b4b38..47dfa31 100644
--- a/arch/arm64/include/asm/cpu_ops.h
+++ b/arch/arm64/include/asm/cpu_ops.h
@@ -28,6 +28,8 @@ struct device_node;
* enable-method property.
* @cpu_init: Reads any data necessary for a specific enable-method from the
* devicetree, for a given cpu node and proposed logical id.
+ * @cpu_init_idle: Reads any data necessary to initialize CPU idle states from
+ * devicetree, for a given cpu node and proposed logical id.
* @cpu_prepare: Early one-time preparation step for a cpu. If there is a
* mechanism for doing so, tests whether it is possible to boot
* the given CPU.
@@ -47,6 +49,7 @@ struct device_node;
struct cpu_operations {
const char *name;
int (*cpu_init)(struct device_node *, unsigned int);
+ int (*cpu_init_idle)(struct device_node *, unsigned int);
int (*cpu_prepare)(unsigned int);
int (*cpu_boot)(unsigned int);
void (*cpu_postboot)(void);
diff --git a/arch/arm64/include/asm/cpuidle.h b/arch/arm64/include/asm/cpuidle.h
new file mode 100644
index 0000000..b52a993
--- /dev/null
+++ b/arch/arm64/include/asm/cpuidle.h
@@ -0,0 +1,13 @@
+#ifndef __ASM_CPUIDLE_H
+#define __ASM_CPUIDLE_H
+
+#ifdef CONFIG_CPU_IDLE
+extern int cpu_init_idle(unsigned int cpu);
+#else
+static inline int cpu_init_idle(unsigned int cpu)
+{
+ return -EOPNOTSUPP;
+}
+#endif
+
+#endif
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 383d81d..be78980 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -27,6 +27,7 @@ arm64-obj-$(CONFIG_PERF_EVENTS) += perf_regs.o
arm64-obj-$(CONFIG_HW_PERF_EVENTS) += perf_event.o
arm64-obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
arm64-obj-$(CONFIG_ARM64_CPU_SUSPEND) += sleep.o suspend.o
+arm64-obj-$(CONFIG_CPU_IDLE) += cpuidle.o
arm64-obj-$(CONFIG_JUMP_LABEL) += jump_label.o
arm64-obj-$(CONFIG_KGDB) += kgdb.o
arm64-obj-$(CONFIG_EFI) += efi.o efi-stub.o efi-entry.o
diff --git a/arch/arm64/kernel/cpuidle.c b/arch/arm64/kernel/cpuidle.c
new file mode 100644
index 0000000..19d17f5
--- /dev/null
+++ b/arch/arm64/kernel/cpuidle.c
@@ -0,0 +1,31 @@
+/*
+ * ARM64 CPU idle arch support
+ *
+ * Copyright (C) 2014 ARM Ltd.
+ * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+#include <asm/cpuidle.h>
+#include <asm/cpu_ops.h>
+
+int cpu_init_idle(unsigned int cpu)
+{
+ int ret = -EOPNOTSUPP;
+ struct device_node *cpu_node = of_cpu_device_node_get(cpu);
+
+ if (!cpu_node)
+ return -ENODEV;
+
+ if (cpu_ops[cpu] && cpu_ops[cpu]->cpu_init_idle)
+ ret = cpu_ops[cpu]->cpu_init_idle(cpu_node, cpu);
+
+ of_node_put(cpu_node);
+ return ret;
+}
--
1.9.1
^ permalink raw reply related [flat|nested] 29+ messages in thread
* [PATCH v9 4/8] arm64: add PSCI CPU_SUSPEND based cpu_suspend support
2014-09-05 17:34 ` Lorenzo Pieralisi
@ 2014-09-05 17:34 ` Lorenzo Pieralisi
-1 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-05 17:34 UTC (permalink / raw)
To: linux-arm-kernel, linux-pm
Cc: devicetree, Lorenzo Pieralisi, Mark Rutland, Sudeep Holla,
Catalin Marinas, Will Deacon, Charles Garcia Tobin, Nicolas Pitre,
Rob Herring, Grant Likely, Peter De Schrijver, Santosh Shilimkar,
Daniel Lezcano, Amit Kucheria, Vincent Guittot, Antti Miettinen,
Stephen Boyd, Kevin Hilman, Sebastian Capella, Mark Brown,
Paul Walmsley, Chander Kashyap, Geoff
This patch implements the cpu_suspend cpu operations method through
the PSCI CPU SUSPEND API. The PSCI implementation translates the idle state
index passed by the cpu_suspend core call into a valid PSCI state according to
the PSCI states initialized at boot through the cpu_init_idle() CPU
operations hook.
The PSCI CPU suspend operation hook checks if the PSCI state is a
standby state. If it is, it calls the PSCI suspend implementation
straight away, without saving any context. If the state is a power
down state the kernel calls the __cpu_suspend API (that saves the CPU
context) and passed the PSCI suspend finisher as a parameter so that PSCI
can be called by the __cpu_suspend implementation after saving and flushing
the context as last function before power down.
For power down states, entry point is set to cpu_resume physical address,
that represents the default kernel execution address following a CPU reset.
Reviewed-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
arch/arm64/kernel/psci.c | 104 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 104 insertions(+)
diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
index 5539547..866c1c8 100644
--- a/arch/arm64/kernel/psci.c
+++ b/arch/arm64/kernel/psci.c
@@ -21,6 +21,7 @@
#include <linux/reboot.h>
#include <linux/pm.h>
#include <linux/delay.h>
+#include <linux/slab.h>
#include <uapi/linux/psci.h>
#include <asm/compiler.h>
@@ -28,6 +29,7 @@
#include <asm/errno.h>
#include <asm/psci.h>
#include <asm/smp_plat.h>
+#include <asm/suspend.h>
#include <asm/system_misc.h>
#define PSCI_POWER_STATE_TYPE_STANDBY 0
@@ -65,6 +67,8 @@ enum psci_function {
PSCI_FN_MAX,
};
+static DEFINE_PER_CPU_READ_MOSTLY(struct psci_power_state *, psci_power_state);
+
static u32 psci_function_id[PSCI_FN_MAX];
static int psci_to_linux_errno(int errno)
@@ -93,6 +97,18 @@ static u32 psci_power_state_pack(struct psci_power_state state)
& PSCI_0_2_POWER_STATE_AFFL_MASK);
}
+static void psci_power_state_unpack(u32 power_state,
+ struct psci_power_state *state)
+{
+ state->id = (power_state & PSCI_0_2_POWER_STATE_ID_MASK) >>
+ PSCI_0_2_POWER_STATE_ID_SHIFT;
+ state->type = (power_state & PSCI_0_2_POWER_STATE_TYPE_MASK) >>
+ PSCI_0_2_POWER_STATE_TYPE_SHIFT;
+ state->affinity_level =
+ (power_state & PSCI_0_2_POWER_STATE_AFFL_MASK) >>
+ PSCI_0_2_POWER_STATE_AFFL_SHIFT;
+}
+
/*
* The following two functions are invoked via the invoke_psci_fn pointer
* and will not be inlined, allowing us to piggyback on the AAPCS.
@@ -199,6 +215,63 @@ static int psci_migrate_info_type(void)
return err;
}
+static int __maybe_unused cpu_psci_cpu_init_idle(struct device_node *cpu_node,
+ unsigned int cpu)
+{
+ int i, ret, count = 0;
+ struct psci_power_state *psci_states;
+ struct device_node *state_node;
+
+ /*
+ * If the PSCI cpu_suspend function hook has not been initialized
+ * idle states must not be enabled, so bail out
+ */
+ if (!psci_ops.cpu_suspend)
+ return -EOPNOTSUPP;
+
+ /* Count idle states */
+ while ((state_node = of_parse_phandle(cpu_node, "cpu-idle-states",
+ count))) {
+ count++;
+ of_node_put(state_node);
+ }
+
+ if (!count)
+ return -ENODEV;
+
+ psci_states = kcalloc(count, sizeof(*psci_states), GFP_KERNEL);
+ if (!psci_states)
+ return -ENOMEM;
+
+ for (i = 0; i < count; i++) {
+ u32 psci_power_state;
+
+ state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i);
+
+ ret = of_property_read_u32(state_node,
+ "arm,psci-suspend-param",
+ &psci_power_state);
+ if (ret) {
+ pr_warn(" * %s missing arm,psci-suspend-param property\n",
+ state_node->full_name);
+ of_node_put(state_node);
+ goto free_mem;
+ }
+
+ of_node_put(state_node);
+ pr_debug("psci-power-state %#x index %d\n", psci_power_state,
+ i);
+ psci_power_state_unpack(psci_power_state, &psci_states[i]);
+ }
+ /* Idle states parsed correctly, initialize per-cpu pointer */
+ per_cpu(psci_power_state, cpu) = psci_states;
+ return 0;
+
+free_mem:
+ kfree(psci_states);
+ return ret;
+}
+
static int get_set_conduit_method(struct device_node *np)
{
const char *method;
@@ -436,8 +509,39 @@ static int cpu_psci_cpu_kill(unsigned int cpu)
#endif
#endif
+static int psci_suspend_finisher(unsigned long index)
+{
+ struct psci_power_state *state = __get_cpu_var(psci_power_state);
+
+ return psci_ops.cpu_suspend(state[index - 1],
+ virt_to_phys(cpu_resume));
+}
+
+static int __maybe_unused cpu_psci_cpu_suspend(unsigned long index)
+{
+ int ret;
+ struct psci_power_state *state = __get_cpu_var(psci_power_state);
+ /*
+ * idle state index 0 corresponds to wfi, should never be called
+ * from the cpu_suspend operations
+ */
+ if (WARN_ON_ONCE(!index))
+ return -EINVAL;
+
+ if (state->type == PSCI_POWER_STATE_TYPE_STANDBY)
+ ret = psci_ops.cpu_suspend(state[index - 1], 0);
+ else
+ ret = __cpu_suspend(index, psci_suspend_finisher);
+
+ return ret;
+}
+
const struct cpu_operations cpu_psci_ops = {
.name = "psci",
+#ifdef CONFIG_CPU_IDLE
+ .cpu_init_idle = cpu_psci_cpu_init_idle,
+ .cpu_suspend = cpu_psci_cpu_suspend,
+#endif
#ifdef CONFIG_SMP
.cpu_init = cpu_psci_cpu_init,
.cpu_prepare = cpu_psci_cpu_prepare,
--
1.9.1
^ permalink raw reply related [flat|nested] 29+ messages in thread
* [PATCH v9 4/8] arm64: add PSCI CPU_SUSPEND based cpu_suspend support
@ 2014-09-05 17:34 ` Lorenzo Pieralisi
0 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-05 17:34 UTC (permalink / raw)
To: linux-arm-kernel
This patch implements the cpu_suspend cpu operations method through
the PSCI CPU SUSPEND API. The PSCI implementation translates the idle state
index passed by the cpu_suspend core call into a valid PSCI state according to
the PSCI states initialized at boot through the cpu_init_idle() CPU
operations hook.
The PSCI CPU suspend operation hook checks if the PSCI state is a
standby state. If it is, it calls the PSCI suspend implementation
straight away, without saving any context. If the state is a power
down state the kernel calls the __cpu_suspend API (that saves the CPU
context) and passed the PSCI suspend finisher as a parameter so that PSCI
can be called by the __cpu_suspend implementation after saving and flushing
the context as last function before power down.
For power down states, entry point is set to cpu_resume physical address,
that represents the default kernel execution address following a CPU reset.
Reviewed-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
arch/arm64/kernel/psci.c | 104 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 104 insertions(+)
diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
index 5539547..866c1c8 100644
--- a/arch/arm64/kernel/psci.c
+++ b/arch/arm64/kernel/psci.c
@@ -21,6 +21,7 @@
#include <linux/reboot.h>
#include <linux/pm.h>
#include <linux/delay.h>
+#include <linux/slab.h>
#include <uapi/linux/psci.h>
#include <asm/compiler.h>
@@ -28,6 +29,7 @@
#include <asm/errno.h>
#include <asm/psci.h>
#include <asm/smp_plat.h>
+#include <asm/suspend.h>
#include <asm/system_misc.h>
#define PSCI_POWER_STATE_TYPE_STANDBY 0
@@ -65,6 +67,8 @@ enum psci_function {
PSCI_FN_MAX,
};
+static DEFINE_PER_CPU_READ_MOSTLY(struct psci_power_state *, psci_power_state);
+
static u32 psci_function_id[PSCI_FN_MAX];
static int psci_to_linux_errno(int errno)
@@ -93,6 +97,18 @@ static u32 psci_power_state_pack(struct psci_power_state state)
& PSCI_0_2_POWER_STATE_AFFL_MASK);
}
+static void psci_power_state_unpack(u32 power_state,
+ struct psci_power_state *state)
+{
+ state->id = (power_state & PSCI_0_2_POWER_STATE_ID_MASK) >>
+ PSCI_0_2_POWER_STATE_ID_SHIFT;
+ state->type = (power_state & PSCI_0_2_POWER_STATE_TYPE_MASK) >>
+ PSCI_0_2_POWER_STATE_TYPE_SHIFT;
+ state->affinity_level =
+ (power_state & PSCI_0_2_POWER_STATE_AFFL_MASK) >>
+ PSCI_0_2_POWER_STATE_AFFL_SHIFT;
+}
+
/*
* The following two functions are invoked via the invoke_psci_fn pointer
* and will not be inlined, allowing us to piggyback on the AAPCS.
@@ -199,6 +215,63 @@ static int psci_migrate_info_type(void)
return err;
}
+static int __maybe_unused cpu_psci_cpu_init_idle(struct device_node *cpu_node,
+ unsigned int cpu)
+{
+ int i, ret, count = 0;
+ struct psci_power_state *psci_states;
+ struct device_node *state_node;
+
+ /*
+ * If the PSCI cpu_suspend function hook has not been initialized
+ * idle states must not be enabled, so bail out
+ */
+ if (!psci_ops.cpu_suspend)
+ return -EOPNOTSUPP;
+
+ /* Count idle states */
+ while ((state_node = of_parse_phandle(cpu_node, "cpu-idle-states",
+ count))) {
+ count++;
+ of_node_put(state_node);
+ }
+
+ if (!count)
+ return -ENODEV;
+
+ psci_states = kcalloc(count, sizeof(*psci_states), GFP_KERNEL);
+ if (!psci_states)
+ return -ENOMEM;
+
+ for (i = 0; i < count; i++) {
+ u32 psci_power_state;
+
+ state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i);
+
+ ret = of_property_read_u32(state_node,
+ "arm,psci-suspend-param",
+ &psci_power_state);
+ if (ret) {
+ pr_warn(" * %s missing arm,psci-suspend-param property\n",
+ state_node->full_name);
+ of_node_put(state_node);
+ goto free_mem;
+ }
+
+ of_node_put(state_node);
+ pr_debug("psci-power-state %#x index %d\n", psci_power_state,
+ i);
+ psci_power_state_unpack(psci_power_state, &psci_states[i]);
+ }
+ /* Idle states parsed correctly, initialize per-cpu pointer */
+ per_cpu(psci_power_state, cpu) = psci_states;
+ return 0;
+
+free_mem:
+ kfree(psci_states);
+ return ret;
+}
+
static int get_set_conduit_method(struct device_node *np)
{
const char *method;
@@ -436,8 +509,39 @@ static int cpu_psci_cpu_kill(unsigned int cpu)
#endif
#endif
+static int psci_suspend_finisher(unsigned long index)
+{
+ struct psci_power_state *state = __get_cpu_var(psci_power_state);
+
+ return psci_ops.cpu_suspend(state[index - 1],
+ virt_to_phys(cpu_resume));
+}
+
+static int __maybe_unused cpu_psci_cpu_suspend(unsigned long index)
+{
+ int ret;
+ struct psci_power_state *state = __get_cpu_var(psci_power_state);
+ /*
+ * idle state index 0 corresponds to wfi, should never be called
+ * from the cpu_suspend operations
+ */
+ if (WARN_ON_ONCE(!index))
+ return -EINVAL;
+
+ if (state->type == PSCI_POWER_STATE_TYPE_STANDBY)
+ ret = psci_ops.cpu_suspend(state[index - 1], 0);
+ else
+ ret = __cpu_suspend(index, psci_suspend_finisher);
+
+ return ret;
+}
+
const struct cpu_operations cpu_psci_ops = {
.name = "psci",
+#ifdef CONFIG_CPU_IDLE
+ .cpu_init_idle = cpu_psci_cpu_init_idle,
+ .cpu_suspend = cpu_psci_cpu_suspend,
+#endif
#ifdef CONFIG_SMP
.cpu_init = cpu_psci_cpu_init,
.cpu_prepare = cpu_psci_cpu_prepare,
--
1.9.1
^ permalink raw reply related [flat|nested] 29+ messages in thread
* [PATCH v9 5/8] drivers: cpuidle: implement DT based idle states infrastructure
2014-09-05 17:34 ` Lorenzo Pieralisi
@ 2014-09-05 17:34 ` Lorenzo Pieralisi
-1 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-05 17:34 UTC (permalink / raw)
To: linux-arm-kernel, linux-pm
Cc: devicetree, Lorenzo Pieralisi, Mark Rutland, Sudeep Holla,
Catalin Marinas, Will Deacon, Charles Garcia Tobin, Nicolas Pitre,
Rob Herring, Grant Likely, Peter De Schrijver, Santosh Shilimkar,
Daniel Lezcano, Amit Kucheria, Vincent Guittot, Antti Miettinen,
Stephen Boyd, Kevin Hilman, Sebastian Capella, Mark Brown,
Paul Walmsley, Chander Kashyap, Geoff
On most common ARM systems, the low-power states a CPU can be put into are
not discoverable in HW and require device tree bindings to describe
power down suspend operations and idle states parameters.
In order to enable DT based idle states and configure idle drivers, this
patch implements the bulk infrastructure required to parse the device tree
idle states bindings and initialize the corresponding CPUidle driver states
data.
The parsing API accepts a start index that defines the first idle state
that should be initialized by the parsing code in order to give new and
legacy driver flexibility over which states should be parsed using the
new DT mechanism.
The idle states node(s) is obtained from the phandle list of the first cpu
in the driver cpumask; the kernel checks that the idle state node phandle
is the same for all CPUs in the driver cpumask before declaring the idle state
as valid and start parsing its content.
The idle state enter function pointer is initialized through DT match
structures passed in by the CPUidle driver, so that ARM legacy code can
cope with platform specific idle entry method based on compatible
string matching and the code used to initialize the enter function pointer
can be moved to the DT generic layer.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
drivers/cpuidle/Kconfig | 3 +
drivers/cpuidle/Makefile | 1 +
drivers/cpuidle/dt_idle_states.c | 213 +++++++++++++++++++++++++++++++++++++++
drivers/cpuidle/dt_idle_states.h | 7 ++
4 files changed, 224 insertions(+)
create mode 100644 drivers/cpuidle/dt_idle_states.c
create mode 100644 drivers/cpuidle/dt_idle_states.h
diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
index 32748c3..8deb934 100644
--- a/drivers/cpuidle/Kconfig
+++ b/drivers/cpuidle/Kconfig
@@ -25,6 +25,9 @@ config CPU_IDLE_GOV_MENU
bool "Menu governor (for tickless system)"
default y
+config DT_IDLE_STATES
+ bool
+
menu "ARM CPU Idle Drivers"
depends on ARM
source "drivers/cpuidle/Kconfig.arm"
diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
index 11edb31..002b653 100644
--- a/drivers/cpuidle/Makefile
+++ b/drivers/cpuidle/Makefile
@@ -4,6 +4,7 @@
obj-y += cpuidle.o driver.o governor.o sysfs.o governors/
obj-$(CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED) += coupled.o
+obj-$(CONFIG_DT_IDLE_STATES) += dt_idle_states.o
##################################################################################
# ARM SoC drivers
diff --git a/drivers/cpuidle/dt_idle_states.c b/drivers/cpuidle/dt_idle_states.c
new file mode 100644
index 0000000..52f4d11
--- /dev/null
+++ b/drivers/cpuidle/dt_idle_states.c
@@ -0,0 +1,213 @@
+/*
+ * DT idle states parsing code.
+ *
+ * Copyright (C) 2014 ARM Ltd.
+ * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#define pr_fmt(fmt) "DT idle-states: " fmt
+
+#include <linux/cpuidle.h>
+#include <linux/cpumask.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+#include "dt_idle_states.h"
+
+static int init_state_node(struct cpuidle_state *idle_state,
+ const struct of_device_id *matches,
+ struct device_node *state_node)
+{
+ int err;
+ const struct of_device_id *match_id;
+
+ match_id = of_match_node(matches, state_node);
+ if (!match_id)
+ return -ENODEV;
+ /*
+ * CPUidle drivers are expected to initialize the const void *data
+ * pointer of the passed in struct of_device_id array to the idle
+ * state enter function.
+ */
+ idle_state->enter = match_id->data;
+
+ err = of_property_read_u32(state_node, "wakeup-latency-us",
+ &idle_state->exit_latency);
+ if (err) {
+ u32 entry_latency, exit_latency;
+
+ err = of_property_read_u32(state_node, "entry-latency-us",
+ &entry_latency);
+ if (err) {
+ pr_debug(" * %s missing entry-latency-us property\n",
+ state_node->full_name);
+ return -EINVAL;
+ }
+
+ err = of_property_read_u32(state_node, "exit-latency-us",
+ &exit_latency);
+ if (err) {
+ pr_debug(" * %s missing exit-latency-us property\n",
+ state_node->full_name);
+ return -EINVAL;
+ }
+ /*
+ * If wakeup-latency-us is missing, default to entry+exit
+ * latencies as defined in idle states bindings
+ */
+ idle_state->exit_latency = entry_latency + exit_latency;
+ }
+
+ err = of_property_read_u32(state_node, "min-residency-us",
+ &idle_state->target_residency);
+ if (err) {
+ pr_debug(" * %s missing min-residency-us property\n",
+ state_node->full_name);
+ return -EINVAL;
+ }
+
+ idle_state->flags = CPUIDLE_FLAG_TIME_VALID;
+ if (of_property_read_bool(state_node, "local-timer-stop"))
+ idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP;
+ /*
+ * TODO:
+ * replace with kstrdup and pointer assignment when name
+ * and desc become string pointers
+ */
+ strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN - 1);
+ strncpy(idle_state->desc, state_node->name, CPUIDLE_DESC_LEN - 1);
+ return 0;
+}
+
+/*
+ * Check that the idle state is uniform across all CPUs in the CPUidle driver
+ * cpumask
+ */
+static bool idle_state_valid(struct device_node *state_node, unsigned int idx,
+ const cpumask_t *cpumask)
+{
+ int cpu;
+ struct device_node *cpu_node, *curr_state_node;
+ bool valid = true;
+
+ /*
+ * Compare idle state phandles for index idx on all CPUs in the
+ * CPUidle driver cpumask. Start from next logical cpu following
+ * cpumask_first(cpumask) since that's the CPU state_node was
+ * retrieved from. If a mismatch is found bail out straight
+ * away since we certainly hit a firmware misconfiguration.
+ */
+ for (cpu = cpumask_next(cpumask_first(cpumask), cpumask);
+ cpu < nr_cpu_ids; cpu = cpumask_next(cpu, cpumask)) {
+ cpu_node = of_cpu_device_node_get(cpu);
+ curr_state_node = of_parse_phandle(cpu_node, "cpu-idle-states",
+ idx);
+ if (state_node != curr_state_node)
+ valid = false;
+
+ of_node_put(curr_state_node);
+ of_node_put(cpu_node);
+ if (!valid)
+ break;
+ }
+
+ return valid;
+}
+
+/**
+ * dt_init_idle_driver() - Parse the DT idle states and initialize the
+ * idle driver states array
+ * @drv: Pointer to CPU idle driver to be initialized
+ * @matches: Array of of_device_id match structures to search in for
+ * compatible idle state nodes. The data pointer for each valid
+ * struct of_device_id entry in the matches array must point to
+ * a function with the following signature, that corresponds to
+ * the CPUidle state enter function signature:
+ *
+ * int (*)(struct cpuidle_device *dev,
+ * struct cpuidle_driver *drv,
+ * int index);
+ *
+ * @start_idx: First idle state index to be initialized
+ *
+ * If DT idle states are detected and are valid the state count and states
+ * array entries in the cpuidle driver are initialized accordingly starting
+ * from index start_idx.
+ *
+ * Return: number of valid DT idle states parsed, <0 on failure
+ */
+int dt_init_idle_driver(struct cpuidle_driver *drv,
+ const struct of_device_id *matches,
+ unsigned int start_idx)
+{
+ struct cpuidle_state *idle_state;
+ struct device_node *state_node, *cpu_node;
+ int i, err = 0;
+ const cpumask_t *cpumask;
+ unsigned int state_idx = start_idx;
+
+ if (state_idx >= CPUIDLE_STATE_MAX)
+ return -EINVAL;
+ /*
+ * We get the idle states for the first logical cpu in the
+ * driver mask (or cpu_possible_mask if the driver cpumask is not set)
+ * and we check through idle_state_valid() if they are uniform
+ * across CPUs, otherwise we hit a firmware misconfiguration.
+ */
+ cpumask = drv->cpumask ? : cpu_possible_mask;
+ cpu_node = of_cpu_device_node_get(cpumask_first(cpumask));
+
+ for (i = 0; ; i++) {
+ state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i);
+ if (!state_node)
+ break;
+
+ if (!idle_state_valid(state_node, i, cpumask)) {
+ pr_warn("%s idle state not valid, bailing out\n",
+ state_node->full_name);
+ err = -EINVAL;
+ break;
+ }
+
+ if (state_idx == CPUIDLE_STATE_MAX) {
+ pr_warn("State index reached static CPU idle driver states array size\n");
+ break;
+ }
+
+ idle_state = &drv->states[state_idx++];
+ err = init_state_node(idle_state, matches, state_node);
+ if (err) {
+ pr_err("Parsing idle state node %s failed with err %d\n",
+ state_node->full_name, err);
+ err = -EINVAL;
+ break;
+ }
+ of_node_put(state_node);
+ }
+
+ of_node_put(state_node);
+ of_node_put(cpu_node);
+ if (err)
+ return err;
+ /*
+ * Update the driver state count only if some valid DT idle states
+ * were detected
+ */
+ if (i)
+ drv->state_count = state_idx;
+
+ /*
+ * Return the number of present and valid DT idle states, which can
+ * also be 0 on platforms with missing DT idle states or legacy DT
+ * configuration predating the DT idle states bindings.
+ */
+ return i;
+}
+EXPORT_SYMBOL_GPL(dt_init_idle_driver);
diff --git a/drivers/cpuidle/dt_idle_states.h b/drivers/cpuidle/dt_idle_states.h
new file mode 100644
index 0000000..4818134
--- /dev/null
+++ b/drivers/cpuidle/dt_idle_states.h
@@ -0,0 +1,7 @@
+#ifndef __DT_IDLE_STATES
+#define __DT_IDLE_STATES
+
+int dt_init_idle_driver(struct cpuidle_driver *drv,
+ const struct of_device_id *matches,
+ unsigned int start_idx);
+#endif
--
1.9.1
^ permalink raw reply related [flat|nested] 29+ messages in thread
* [PATCH v9 5/8] drivers: cpuidle: implement DT based idle states infrastructure
@ 2014-09-05 17:34 ` Lorenzo Pieralisi
0 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-05 17:34 UTC (permalink / raw)
To: linux-arm-kernel
On most common ARM systems, the low-power states a CPU can be put into are
not discoverable in HW and require device tree bindings to describe
power down suspend operations and idle states parameters.
In order to enable DT based idle states and configure idle drivers, this
patch implements the bulk infrastructure required to parse the device tree
idle states bindings and initialize the corresponding CPUidle driver states
data.
The parsing API accepts a start index that defines the first idle state
that should be initialized by the parsing code in order to give new and
legacy driver flexibility over which states should be parsed using the
new DT mechanism.
The idle states node(s) is obtained from the phandle list of the first cpu
in the driver cpumask; the kernel checks that the idle state node phandle
is the same for all CPUs in the driver cpumask before declaring the idle state
as valid and start parsing its content.
The idle state enter function pointer is initialized through DT match
structures passed in by the CPUidle driver, so that ARM legacy code can
cope with platform specific idle entry method based on compatible
string matching and the code used to initialize the enter function pointer
can be moved to the DT generic layer.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
drivers/cpuidle/Kconfig | 3 +
drivers/cpuidle/Makefile | 1 +
drivers/cpuidle/dt_idle_states.c | 213 +++++++++++++++++++++++++++++++++++++++
drivers/cpuidle/dt_idle_states.h | 7 ++
4 files changed, 224 insertions(+)
create mode 100644 drivers/cpuidle/dt_idle_states.c
create mode 100644 drivers/cpuidle/dt_idle_states.h
diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
index 32748c3..8deb934 100644
--- a/drivers/cpuidle/Kconfig
+++ b/drivers/cpuidle/Kconfig
@@ -25,6 +25,9 @@ config CPU_IDLE_GOV_MENU
bool "Menu governor (for tickless system)"
default y
+config DT_IDLE_STATES
+ bool
+
menu "ARM CPU Idle Drivers"
depends on ARM
source "drivers/cpuidle/Kconfig.arm"
diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
index 11edb31..002b653 100644
--- a/drivers/cpuidle/Makefile
+++ b/drivers/cpuidle/Makefile
@@ -4,6 +4,7 @@
obj-y += cpuidle.o driver.o governor.o sysfs.o governors/
obj-$(CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED) += coupled.o
+obj-$(CONFIG_DT_IDLE_STATES) += dt_idle_states.o
##################################################################################
# ARM SoC drivers
diff --git a/drivers/cpuidle/dt_idle_states.c b/drivers/cpuidle/dt_idle_states.c
new file mode 100644
index 0000000..52f4d11
--- /dev/null
+++ b/drivers/cpuidle/dt_idle_states.c
@@ -0,0 +1,213 @@
+/*
+ * DT idle states parsing code.
+ *
+ * Copyright (C) 2014 ARM Ltd.
+ * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#define pr_fmt(fmt) "DT idle-states: " fmt
+
+#include <linux/cpuidle.h>
+#include <linux/cpumask.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+
+#include "dt_idle_states.h"
+
+static int init_state_node(struct cpuidle_state *idle_state,
+ const struct of_device_id *matches,
+ struct device_node *state_node)
+{
+ int err;
+ const struct of_device_id *match_id;
+
+ match_id = of_match_node(matches, state_node);
+ if (!match_id)
+ return -ENODEV;
+ /*
+ * CPUidle drivers are expected to initialize the const void *data
+ * pointer of the passed in struct of_device_id array to the idle
+ * state enter function.
+ */
+ idle_state->enter = match_id->data;
+
+ err = of_property_read_u32(state_node, "wakeup-latency-us",
+ &idle_state->exit_latency);
+ if (err) {
+ u32 entry_latency, exit_latency;
+
+ err = of_property_read_u32(state_node, "entry-latency-us",
+ &entry_latency);
+ if (err) {
+ pr_debug(" * %s missing entry-latency-us property\n",
+ state_node->full_name);
+ return -EINVAL;
+ }
+
+ err = of_property_read_u32(state_node, "exit-latency-us",
+ &exit_latency);
+ if (err) {
+ pr_debug(" * %s missing exit-latency-us property\n",
+ state_node->full_name);
+ return -EINVAL;
+ }
+ /*
+ * If wakeup-latency-us is missing, default to entry+exit
+ * latencies as defined in idle states bindings
+ */
+ idle_state->exit_latency = entry_latency + exit_latency;
+ }
+
+ err = of_property_read_u32(state_node, "min-residency-us",
+ &idle_state->target_residency);
+ if (err) {
+ pr_debug(" * %s missing min-residency-us property\n",
+ state_node->full_name);
+ return -EINVAL;
+ }
+
+ idle_state->flags = CPUIDLE_FLAG_TIME_VALID;
+ if (of_property_read_bool(state_node, "local-timer-stop"))
+ idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP;
+ /*
+ * TODO:
+ * replace with kstrdup and pointer assignment when name
+ * and desc become string pointers
+ */
+ strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN - 1);
+ strncpy(idle_state->desc, state_node->name, CPUIDLE_DESC_LEN - 1);
+ return 0;
+}
+
+/*
+ * Check that the idle state is uniform across all CPUs in the CPUidle driver
+ * cpumask
+ */
+static bool idle_state_valid(struct device_node *state_node, unsigned int idx,
+ const cpumask_t *cpumask)
+{
+ int cpu;
+ struct device_node *cpu_node, *curr_state_node;
+ bool valid = true;
+
+ /*
+ * Compare idle state phandles for index idx on all CPUs in the
+ * CPUidle driver cpumask. Start from next logical cpu following
+ * cpumask_first(cpumask) since that's the CPU state_node was
+ * retrieved from. If a mismatch is found bail out straight
+ * away since we certainly hit a firmware misconfiguration.
+ */
+ for (cpu = cpumask_next(cpumask_first(cpumask), cpumask);
+ cpu < nr_cpu_ids; cpu = cpumask_next(cpu, cpumask)) {
+ cpu_node = of_cpu_device_node_get(cpu);
+ curr_state_node = of_parse_phandle(cpu_node, "cpu-idle-states",
+ idx);
+ if (state_node != curr_state_node)
+ valid = false;
+
+ of_node_put(curr_state_node);
+ of_node_put(cpu_node);
+ if (!valid)
+ break;
+ }
+
+ return valid;
+}
+
+/**
+ * dt_init_idle_driver() - Parse the DT idle states and initialize the
+ * idle driver states array
+ * @drv: Pointer to CPU idle driver to be initialized
+ * @matches: Array of of_device_id match structures to search in for
+ * compatible idle state nodes. The data pointer for each valid
+ * struct of_device_id entry in the matches array must point to
+ * a function with the following signature, that corresponds to
+ * the CPUidle state enter function signature:
+ *
+ * int (*)(struct cpuidle_device *dev,
+ * struct cpuidle_driver *drv,
+ * int index);
+ *
+ * @start_idx: First idle state index to be initialized
+ *
+ * If DT idle states are detected and are valid the state count and states
+ * array entries in the cpuidle driver are initialized accordingly starting
+ * from index start_idx.
+ *
+ * Return: number of valid DT idle states parsed, <0 on failure
+ */
+int dt_init_idle_driver(struct cpuidle_driver *drv,
+ const struct of_device_id *matches,
+ unsigned int start_idx)
+{
+ struct cpuidle_state *idle_state;
+ struct device_node *state_node, *cpu_node;
+ int i, err = 0;
+ const cpumask_t *cpumask;
+ unsigned int state_idx = start_idx;
+
+ if (state_idx >= CPUIDLE_STATE_MAX)
+ return -EINVAL;
+ /*
+ * We get the idle states for the first logical cpu in the
+ * driver mask (or cpu_possible_mask if the driver cpumask is not set)
+ * and we check through idle_state_valid() if they are uniform
+ * across CPUs, otherwise we hit a firmware misconfiguration.
+ */
+ cpumask = drv->cpumask ? : cpu_possible_mask;
+ cpu_node = of_cpu_device_node_get(cpumask_first(cpumask));
+
+ for (i = 0; ; i++) {
+ state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i);
+ if (!state_node)
+ break;
+
+ if (!idle_state_valid(state_node, i, cpumask)) {
+ pr_warn("%s idle state not valid, bailing out\n",
+ state_node->full_name);
+ err = -EINVAL;
+ break;
+ }
+
+ if (state_idx == CPUIDLE_STATE_MAX) {
+ pr_warn("State index reached static CPU idle driver states array size\n");
+ break;
+ }
+
+ idle_state = &drv->states[state_idx++];
+ err = init_state_node(idle_state, matches, state_node);
+ if (err) {
+ pr_err("Parsing idle state node %s failed with err %d\n",
+ state_node->full_name, err);
+ err = -EINVAL;
+ break;
+ }
+ of_node_put(state_node);
+ }
+
+ of_node_put(state_node);
+ of_node_put(cpu_node);
+ if (err)
+ return err;
+ /*
+ * Update the driver state count only if some valid DT idle states
+ * were detected
+ */
+ if (i)
+ drv->state_count = state_idx;
+
+ /*
+ * Return the number of present and valid DT idle states, which can
+ * also be 0 on platforms with missing DT idle states or legacy DT
+ * configuration predating the DT idle states bindings.
+ */
+ return i;
+}
+EXPORT_SYMBOL_GPL(dt_init_idle_driver);
diff --git a/drivers/cpuidle/dt_idle_states.h b/drivers/cpuidle/dt_idle_states.h
new file mode 100644
index 0000000..4818134
--- /dev/null
+++ b/drivers/cpuidle/dt_idle_states.h
@@ -0,0 +1,7 @@
+#ifndef __DT_IDLE_STATES
+#define __DT_IDLE_STATES
+
+int dt_init_idle_driver(struct cpuidle_driver *drv,
+ const struct of_device_id *matches,
+ unsigned int start_idx);
+#endif
--
1.9.1
^ permalink raw reply related [flat|nested] 29+ messages in thread
* [PATCH v9 6/8] drivers: cpuidle: CPU idle ARM64 driver
2014-09-05 17:34 ` Lorenzo Pieralisi
@ 2014-09-05 17:34 ` Lorenzo Pieralisi
-1 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-05 17:34 UTC (permalink / raw)
To: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r,
linux-pm-u79uwXL29TY76Z2rM5mHXA
Cc: devicetree-u79uwXL29TY76Z2rM5mHXA, Lorenzo Pieralisi,
Mark Rutland, Sudeep Holla, Catalin Marinas, Will Deacon,
Charles Garcia Tobin, Nicolas Pitre, Rob Herring, Grant Likely,
Peter De Schrijver, Santosh Shilimkar, Daniel Lezcano,
Amit Kucheria, Vincent Guittot, Antti Miettinen, Stephen Boyd,
Kevin Hilman, Sebastian Capella, Mark Brown, Paul Walmsley,
Chander Kashyap, Geoff
This patch implements a generic CPU idle driver for ARM64 machines.
It relies on the DT idle states infrastructure to initialize idle
states count and respective parameters. Current code assumes the driver
is managing idle states on all possible CPUs but can be easily
generalized to support heterogenous systems and build cpumasks at
runtime using MIDRs or DT cpu nodes compatible properties.
The driver relies on the arm64 CPU operations to call the idle
initialization hook used to parse and save suspend back-end specific
idle states information upon probing.
Idle state index 0 is always initialized as a simple wfi state, ie always
considered present and functional on all ARM64 platforms.
Idle state indices higher than 0 trigger idle state entry by calling
the cpu_suspend function, that triggers the suspend operation through
the CPU operations suspend back-end hook. cpu_suspend passes the idle
state index as a parameter so that the CPU operations suspend back-end
can retrieve the required idle state data by using the idle state
index to execute a look-up on its internal data structures.
Reviewed-by: Ashwin Chaugule <ashwin.chaugule-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Reviewed-by: Catalin Marinas <catalin.marinas-5wv7dgnIgG8@public.gmane.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi-5wv7dgnIgG8@public.gmane.org>
---
drivers/cpuidle/Kconfig | 5 ++
drivers/cpuidle/Kconfig.arm64 | 14 +++++
drivers/cpuidle/Makefile | 4 ++
drivers/cpuidle/cpuidle-arm64.c | 133 ++++++++++++++++++++++++++++++++++++++++
4 files changed, 156 insertions(+)
create mode 100644 drivers/cpuidle/Kconfig.arm64
create mode 100644 drivers/cpuidle/cpuidle-arm64.c
diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
index 8deb934..c5029c1 100644
--- a/drivers/cpuidle/Kconfig
+++ b/drivers/cpuidle/Kconfig
@@ -33,6 +33,11 @@ depends on ARM
source "drivers/cpuidle/Kconfig.arm"
endmenu
+menu "ARM64 CPU Idle Drivers"
+depends on ARM64
+source "drivers/cpuidle/Kconfig.arm64"
+endmenu
+
menu "MIPS CPU Idle Drivers"
depends on MIPS
source "drivers/cpuidle/Kconfig.mips"
diff --git a/drivers/cpuidle/Kconfig.arm64 b/drivers/cpuidle/Kconfig.arm64
new file mode 100644
index 0000000..d0a08ed
--- /dev/null
+++ b/drivers/cpuidle/Kconfig.arm64
@@ -0,0 +1,14 @@
+#
+# ARM64 CPU Idle drivers
+#
+
+config ARM64_CPUIDLE
+ bool "Generic ARM64 CPU idle Driver"
+ select ARM64_CPU_SUSPEND
+ select DT_IDLE_STATES
+ help
+ Select this to enable generic cpuidle driver for ARM64.
+ It provides a generic idle driver whose idle states are configured
+ at run-time through DT nodes. The CPUidle suspend backend is
+ initialized by calling the CPU operations init idle hook
+ provided by architecture code.
diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
index 002b653..4d177b9 100644
--- a/drivers/cpuidle/Makefile
+++ b/drivers/cpuidle/Makefile
@@ -23,6 +23,10 @@ obj-$(CONFIG_ARM_EXYNOS_CPUIDLE) += cpuidle-exynos.o
obj-$(CONFIG_MIPS_CPS_CPUIDLE) += cpuidle-cps.o
###############################################################################
+# ARM64 drivers
+obj-$(CONFIG_ARM64_CPUIDLE) += cpuidle-arm64.o
+
+###############################################################################
# POWERPC drivers
obj-$(CONFIG_PSERIES_CPUIDLE) += cpuidle-pseries.o
obj-$(CONFIG_POWERNV_CPUIDLE) += cpuidle-powernv.o
diff --git a/drivers/cpuidle/cpuidle-arm64.c b/drivers/cpuidle/cpuidle-arm64.c
new file mode 100644
index 0000000..50997ea
--- /dev/null
+++ b/drivers/cpuidle/cpuidle-arm64.c
@@ -0,0 +1,133 @@
+/*
+ * ARM64 generic CPU idle driver.
+ *
+ * Copyright (C) 2014 ARM Ltd.
+ * Author: Lorenzo Pieralisi <lorenzo.pieralisi-5wv7dgnIgG8@public.gmane.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#define pr_fmt(fmt) "CPUidle arm64: " fmt
+
+#include <linux/cpuidle.h>
+#include <linux/cpumask.h>
+#include <linux/cpu_pm.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+
+#include <asm/cpuidle.h>
+#include <asm/suspend.h>
+
+#include "dt_idle_states.h"
+
+/*
+ * arm64_enter_idle_state - Programs CPU to enter the specified state
+ *
+ * dev: cpuidle device
+ * drv: cpuidle driver
+ * idx: state index
+ *
+ * Called from the CPUidle framework to program the device to the
+ * specified target state selected by the governor.
+ */
+static int arm64_enter_idle_state(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int idx)
+{
+ int ret;
+
+ if (!idx) {
+ cpu_do_idle();
+ return idx;
+ }
+
+ ret = cpu_pm_enter();
+ if (!ret) {
+ /*
+ * Pass idle state index to cpu_suspend which in turn will
+ * call the CPU ops suspend protocol with idle index as a
+ * parameter.
+ */
+ ret = cpu_suspend(idx);
+
+ cpu_pm_exit();
+ }
+
+ return ret ? -1 : idx;
+}
+
+static struct cpuidle_driver arm64_idle_driver = {
+ .name = "arm64_idle",
+ .owner = THIS_MODULE,
+ /*
+ * State at index 0 is standby wfi and considered standard
+ * on all ARM platforms. If in some platforms simple wfi
+ * can't be used as "state 0", DT bindings must be implemented
+ * to work around this issue and allow installing a special
+ * handler for idle state index 0.
+ */
+ .states[0] = {
+ .enter = arm64_enter_idle_state,
+ .exit_latency = 1,
+ .target_residency = 1,
+ .power_usage = UINT_MAX,
+ .flags = CPUIDLE_FLAG_TIME_VALID,
+ .name = "WFI",
+ .desc = "ARM64 WFI",
+ }
+};
+
+static const struct of_device_id arm64_idle_state_match[] __initconst = {
+ { .compatible = "arm,idle-state",
+ .data = arm64_enter_idle_state },
+ { },
+};
+
+/*
+ * arm64_idle_init
+ *
+ * Registers the arm64 specific cpuidle driver with the cpuidle
+ * framework. It relies on core code to parse the idle states
+ * and initialize them using driver data structures accordingly.
+ */
+static int __init arm64_idle_init(void)
+{
+ int cpu, ret;
+ struct cpuidle_driver *drv = &arm64_idle_driver;
+
+ /*
+ * Initialize idle states data, starting at index 1.
+ * This driver is DT only, if no DT idle states are detected (ret == 0)
+ * let the driver initialization fail accordingly since there is no
+ * reason to initialize the idle driver if only wfi is supported.
+ */
+ ret = dt_init_idle_driver(drv, arm64_idle_state_match, 1);
+ if (ret <= 0) {
+ if (ret)
+ pr_err("failed to initialize idle states\n");
+ return ret ? : -ENODEV;
+ }
+
+ /*
+ * Call arch CPU operations in order to initialize
+ * idle states suspend back-end specific data
+ */
+ for_each_possible_cpu(cpu) {
+ ret = cpu_init_idle(cpu);
+ if (ret) {
+ pr_err("CPU %d failed to init idle CPU ops\n", cpu);
+ return ret;
+ }
+ }
+
+ ret = cpuidle_register(drv, NULL);
+ if (ret) {
+ pr_err("failed to register cpuidle driver\n");
+ return ret;
+ }
+
+ return 0;
+}
+device_initcall(arm64_idle_init);
--
1.9.1
--
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^ permalink raw reply related [flat|nested] 29+ messages in thread
* [PATCH v9 6/8] drivers: cpuidle: CPU idle ARM64 driver
@ 2014-09-05 17:34 ` Lorenzo Pieralisi
0 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-05 17:34 UTC (permalink / raw)
To: linux-arm-kernel
This patch implements a generic CPU idle driver for ARM64 machines.
It relies on the DT idle states infrastructure to initialize idle
states count and respective parameters. Current code assumes the driver
is managing idle states on all possible CPUs but can be easily
generalized to support heterogenous systems and build cpumasks at
runtime using MIDRs or DT cpu nodes compatible properties.
The driver relies on the arm64 CPU operations to call the idle
initialization hook used to parse and save suspend back-end specific
idle states information upon probing.
Idle state index 0 is always initialized as a simple wfi state, ie always
considered present and functional on all ARM64 platforms.
Idle state indices higher than 0 trigger idle state entry by calling
the cpu_suspend function, that triggers the suspend operation through
the CPU operations suspend back-end hook. cpu_suspend passes the idle
state index as a parameter so that the CPU operations suspend back-end
can retrieve the required idle state data by using the idle state
index to execute a look-up on its internal data structures.
Reviewed-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
drivers/cpuidle/Kconfig | 5 ++
drivers/cpuidle/Kconfig.arm64 | 14 +++++
drivers/cpuidle/Makefile | 4 ++
drivers/cpuidle/cpuidle-arm64.c | 133 ++++++++++++++++++++++++++++++++++++++++
4 files changed, 156 insertions(+)
create mode 100644 drivers/cpuidle/Kconfig.arm64
create mode 100644 drivers/cpuidle/cpuidle-arm64.c
diff --git a/drivers/cpuidle/Kconfig b/drivers/cpuidle/Kconfig
index 8deb934..c5029c1 100644
--- a/drivers/cpuidle/Kconfig
+++ b/drivers/cpuidle/Kconfig
@@ -33,6 +33,11 @@ depends on ARM
source "drivers/cpuidle/Kconfig.arm"
endmenu
+menu "ARM64 CPU Idle Drivers"
+depends on ARM64
+source "drivers/cpuidle/Kconfig.arm64"
+endmenu
+
menu "MIPS CPU Idle Drivers"
depends on MIPS
source "drivers/cpuidle/Kconfig.mips"
diff --git a/drivers/cpuidle/Kconfig.arm64 b/drivers/cpuidle/Kconfig.arm64
new file mode 100644
index 0000000..d0a08ed
--- /dev/null
+++ b/drivers/cpuidle/Kconfig.arm64
@@ -0,0 +1,14 @@
+#
+# ARM64 CPU Idle drivers
+#
+
+config ARM64_CPUIDLE
+ bool "Generic ARM64 CPU idle Driver"
+ select ARM64_CPU_SUSPEND
+ select DT_IDLE_STATES
+ help
+ Select this to enable generic cpuidle driver for ARM64.
+ It provides a generic idle driver whose idle states are configured
+ at run-time through DT nodes. The CPUidle suspend backend is
+ initialized by calling the CPU operations init idle hook
+ provided by architecture code.
diff --git a/drivers/cpuidle/Makefile b/drivers/cpuidle/Makefile
index 002b653..4d177b9 100644
--- a/drivers/cpuidle/Makefile
+++ b/drivers/cpuidle/Makefile
@@ -23,6 +23,10 @@ obj-$(CONFIG_ARM_EXYNOS_CPUIDLE) += cpuidle-exynos.o
obj-$(CONFIG_MIPS_CPS_CPUIDLE) += cpuidle-cps.o
###############################################################################
+# ARM64 drivers
+obj-$(CONFIG_ARM64_CPUIDLE) += cpuidle-arm64.o
+
+###############################################################################
# POWERPC drivers
obj-$(CONFIG_PSERIES_CPUIDLE) += cpuidle-pseries.o
obj-$(CONFIG_POWERNV_CPUIDLE) += cpuidle-powernv.o
diff --git a/drivers/cpuidle/cpuidle-arm64.c b/drivers/cpuidle/cpuidle-arm64.c
new file mode 100644
index 0000000..50997ea
--- /dev/null
+++ b/drivers/cpuidle/cpuidle-arm64.c
@@ -0,0 +1,133 @@
+/*
+ * ARM64 generic CPU idle driver.
+ *
+ * Copyright (C) 2014 ARM Ltd.
+ * Author: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#define pr_fmt(fmt) "CPUidle arm64: " fmt
+
+#include <linux/cpuidle.h>
+#include <linux/cpumask.h>
+#include <linux/cpu_pm.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+
+#include <asm/cpuidle.h>
+#include <asm/suspend.h>
+
+#include "dt_idle_states.h"
+
+/*
+ * arm64_enter_idle_state - Programs CPU to enter the specified state
+ *
+ * dev: cpuidle device
+ * drv: cpuidle driver
+ * idx: state index
+ *
+ * Called from the CPUidle framework to program the device to the
+ * specified target state selected by the governor.
+ */
+static int arm64_enter_idle_state(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv, int idx)
+{
+ int ret;
+
+ if (!idx) {
+ cpu_do_idle();
+ return idx;
+ }
+
+ ret = cpu_pm_enter();
+ if (!ret) {
+ /*
+ * Pass idle state index to cpu_suspend which in turn will
+ * call the CPU ops suspend protocol with idle index as a
+ * parameter.
+ */
+ ret = cpu_suspend(idx);
+
+ cpu_pm_exit();
+ }
+
+ return ret ? -1 : idx;
+}
+
+static struct cpuidle_driver arm64_idle_driver = {
+ .name = "arm64_idle",
+ .owner = THIS_MODULE,
+ /*
+ * State at index 0 is standby wfi and considered standard
+ * on all ARM platforms. If in some platforms simple wfi
+ * can't be used as "state 0", DT bindings must be implemented
+ * to work around this issue and allow installing a special
+ * handler for idle state index 0.
+ */
+ .states[0] = {
+ .enter = arm64_enter_idle_state,
+ .exit_latency = 1,
+ .target_residency = 1,
+ .power_usage = UINT_MAX,
+ .flags = CPUIDLE_FLAG_TIME_VALID,
+ .name = "WFI",
+ .desc = "ARM64 WFI",
+ }
+};
+
+static const struct of_device_id arm64_idle_state_match[] __initconst = {
+ { .compatible = "arm,idle-state",
+ .data = arm64_enter_idle_state },
+ { },
+};
+
+/*
+ * arm64_idle_init
+ *
+ * Registers the arm64 specific cpuidle driver with the cpuidle
+ * framework. It relies on core code to parse the idle states
+ * and initialize them using driver data structures accordingly.
+ */
+static int __init arm64_idle_init(void)
+{
+ int cpu, ret;
+ struct cpuidle_driver *drv = &arm64_idle_driver;
+
+ /*
+ * Initialize idle states data, starting at index 1.
+ * This driver is DT only, if no DT idle states are detected (ret == 0)
+ * let the driver initialization fail accordingly since there is no
+ * reason to initialize the idle driver if only wfi is supported.
+ */
+ ret = dt_init_idle_driver(drv, arm64_idle_state_match, 1);
+ if (ret <= 0) {
+ if (ret)
+ pr_err("failed to initialize idle states\n");
+ return ret ? : -ENODEV;
+ }
+
+ /*
+ * Call arch CPU operations in order to initialize
+ * idle states suspend back-end specific data
+ */
+ for_each_possible_cpu(cpu) {
+ ret = cpu_init_idle(cpu);
+ if (ret) {
+ pr_err("CPU %d failed to init idle CPU ops\n", cpu);
+ return ret;
+ }
+ }
+
+ ret = cpuidle_register(drv, NULL);
+ if (ret) {
+ pr_err("failed to register cpuidle driver\n");
+ return ret;
+ }
+
+ return 0;
+}
+device_initcall(arm64_idle_init);
--
1.9.1
^ permalink raw reply related [flat|nested] 29+ messages in thread
* [PATCH v9 7/8] drivers: cpuidle: initialize big.LITTLE driver through DT
2014-09-05 17:34 ` Lorenzo Pieralisi
@ 2014-09-05 17:34 ` Lorenzo Pieralisi
-1 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-05 17:34 UTC (permalink / raw)
To: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r,
linux-pm-u79uwXL29TY76Z2rM5mHXA
Cc: devicetree-u79uwXL29TY76Z2rM5mHXA, Lorenzo Pieralisi,
Chander Kashyap, Mark Rutland, Sudeep Holla, Catalin Marinas,
Will Deacon, Charles Garcia Tobin, Nicolas Pitre, Rob Herring,
Grant Likely, Peter De Schrijver, Santosh Shilimkar,
Daniel Lezcano, Amit Kucheria, Vincent Guittot, Antti Miettinen,
Stephen Boyd, Kevin Hilman, Sebastian Capella, Mark Brown,
Paul Walmsley, Geoff
With the introduction of DT based idle states, CPUidle drivers for ARM
can now initialize idle states data through properties in the device tree.
This patch adds code to the big.LITTLE CPUidle driver to dynamically
initialize idle states data through the updated device tree source file.
Cc: Chander Kashyap <k.chander-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
Acked-by: Catalin Marinas <catalin.marinas-5wv7dgnIgG8@public.gmane.org>
Acked-by: Daniel Lezcano <daniel.lezcano-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi-5wv7dgnIgG8@public.gmane.org>
---
arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts | 23 +++++++++++++++++++++++
drivers/cpuidle/Kconfig.arm | 1 +
drivers/cpuidle/cpuidle-big_little.c | 19 +++++++++++++++++++
3 files changed, 43 insertions(+)
diff --git a/arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts b/arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts
index a25c262..322fd15 100644
--- a/arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts
+++ b/arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts
@@ -38,6 +38,7 @@
compatible = "arm,cortex-a15";
reg = <0>;
cci-control-port = <&cci_control1>;
+ cpu-idle-states = <&CLUSTER_SLEEP_BIG>;
};
cpu1: cpu@1 {
@@ -45,6 +46,7 @@
compatible = "arm,cortex-a15";
reg = <1>;
cci-control-port = <&cci_control1>;
+ cpu-idle-states = <&CLUSTER_SLEEP_BIG>;
};
cpu2: cpu@2 {
@@ -52,6 +54,7 @@
compatible = "arm,cortex-a7";
reg = <0x100>;
cci-control-port = <&cci_control2>;
+ cpu-idle-states = <&CLUSTER_SLEEP_LITTLE>;
};
cpu3: cpu@3 {
@@ -59,6 +62,7 @@
compatible = "arm,cortex-a7";
reg = <0x101>;
cci-control-port = <&cci_control2>;
+ cpu-idle-states = <&CLUSTER_SLEEP_LITTLE>;
};
cpu4: cpu@4 {
@@ -66,6 +70,25 @@
compatible = "arm,cortex-a7";
reg = <0x102>;
cci-control-port = <&cci_control2>;
+ cpu-idle-states = <&CLUSTER_SLEEP_LITTLE>;
+ };
+
+ idle-states {
+ CLUSTER_SLEEP_BIG: cluster-sleep-big {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ entry-latency-us = <1000>;
+ exit-latency-us = <700>;
+ min-residency-us = <2000>;
+ };
+
+ CLUSTER_SLEEP_LITTLE: cluster-sleep-little {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ entry-latency-us = <1000>;
+ exit-latency-us = <500>;
+ min-residency-us = <2500>;
+ };
};
};
diff --git a/drivers/cpuidle/Kconfig.arm b/drivers/cpuidle/Kconfig.arm
index 38cff69..e339c7f 100644
--- a/drivers/cpuidle/Kconfig.arm
+++ b/drivers/cpuidle/Kconfig.arm
@@ -7,6 +7,7 @@ config ARM_BIG_LITTLE_CPUIDLE
depends on MCPM
select ARM_CPU_SUSPEND
select CPU_IDLE_MULTIPLE_DRIVERS
+ select DT_IDLE_STATES
help
Select this option to enable CPU idle driver for big.LITTLE based
ARM systems. Driver manages CPUs coordination through MCPM and
diff --git a/drivers/cpuidle/cpuidle-big_little.c b/drivers/cpuidle/cpuidle-big_little.c
index ef94c3b..85d09bc 100644
--- a/drivers/cpuidle/cpuidle-big_little.c
+++ b/drivers/cpuidle/cpuidle-big_little.c
@@ -24,6 +24,8 @@
#include <asm/smp_plat.h>
#include <asm/suspend.h>
+#include "dt_idle_states.h"
+
static int bl_enter_powerdown(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int idx);
@@ -73,6 +75,12 @@ static struct cpuidle_driver bl_idle_little_driver = {
.state_count = 2,
};
+static const struct of_device_id bl_idle_state_match[] __initconst = {
+ { .compatible = "arm,idle-state",
+ .data = bl_enter_powerdown },
+ { },
+};
+
static struct cpuidle_driver bl_idle_big_driver = {
.name = "big_idle",
.owner = THIS_MODULE,
@@ -190,6 +198,17 @@ static int __init bl_idle_init(void)
if (ret)
goto out_uninit_little;
+ /* Start at index 1, index 0 standard WFI */
+ ret = dt_init_idle_driver(&bl_idle_big_driver, bl_idle_state_match, 1);
+ if (ret < 0)
+ goto out_uninit_big;
+
+ /* Start at index 1, index 0 standard WFI */
+ ret = dt_init_idle_driver(&bl_idle_little_driver,
+ bl_idle_state_match, 1);
+ if (ret < 0)
+ goto out_uninit_big;
+
ret = cpuidle_register(&bl_idle_little_driver, NULL);
if (ret)
goto out_uninit_big;
--
1.9.1
--
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^ permalink raw reply related [flat|nested] 29+ messages in thread
* [PATCH v9 7/8] drivers: cpuidle: initialize big.LITTLE driver through DT
@ 2014-09-05 17:34 ` Lorenzo Pieralisi
0 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-05 17:34 UTC (permalink / raw)
To: linux-arm-kernel
With the introduction of DT based idle states, CPUidle drivers for ARM
can now initialize idle states data through properties in the device tree.
This patch adds code to the big.LITTLE CPUidle driver to dynamically
initialize idle states data through the updated device tree source file.
Cc: Chander Kashyap <k.chander@samsung.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts | 23 +++++++++++++++++++++++
drivers/cpuidle/Kconfig.arm | 1 +
drivers/cpuidle/cpuidle-big_little.c | 19 +++++++++++++++++++
3 files changed, 43 insertions(+)
diff --git a/arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts b/arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts
index a25c262..322fd15 100644
--- a/arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts
+++ b/arch/arm/boot/dts/vexpress-v2p-ca15_a7.dts
@@ -38,6 +38,7 @@
compatible = "arm,cortex-a15";
reg = <0>;
cci-control-port = <&cci_control1>;
+ cpu-idle-states = <&CLUSTER_SLEEP_BIG>;
};
cpu1: cpu at 1 {
@@ -45,6 +46,7 @@
compatible = "arm,cortex-a15";
reg = <1>;
cci-control-port = <&cci_control1>;
+ cpu-idle-states = <&CLUSTER_SLEEP_BIG>;
};
cpu2: cpu at 2 {
@@ -52,6 +54,7 @@
compatible = "arm,cortex-a7";
reg = <0x100>;
cci-control-port = <&cci_control2>;
+ cpu-idle-states = <&CLUSTER_SLEEP_LITTLE>;
};
cpu3: cpu at 3 {
@@ -59,6 +62,7 @@
compatible = "arm,cortex-a7";
reg = <0x101>;
cci-control-port = <&cci_control2>;
+ cpu-idle-states = <&CLUSTER_SLEEP_LITTLE>;
};
cpu4: cpu at 4 {
@@ -66,6 +70,25 @@
compatible = "arm,cortex-a7";
reg = <0x102>;
cci-control-port = <&cci_control2>;
+ cpu-idle-states = <&CLUSTER_SLEEP_LITTLE>;
+ };
+
+ idle-states {
+ CLUSTER_SLEEP_BIG: cluster-sleep-big {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ entry-latency-us = <1000>;
+ exit-latency-us = <700>;
+ min-residency-us = <2000>;
+ };
+
+ CLUSTER_SLEEP_LITTLE: cluster-sleep-little {
+ compatible = "arm,idle-state";
+ local-timer-stop;
+ entry-latency-us = <1000>;
+ exit-latency-us = <500>;
+ min-residency-us = <2500>;
+ };
};
};
diff --git a/drivers/cpuidle/Kconfig.arm b/drivers/cpuidle/Kconfig.arm
index 38cff69..e339c7f 100644
--- a/drivers/cpuidle/Kconfig.arm
+++ b/drivers/cpuidle/Kconfig.arm
@@ -7,6 +7,7 @@ config ARM_BIG_LITTLE_CPUIDLE
depends on MCPM
select ARM_CPU_SUSPEND
select CPU_IDLE_MULTIPLE_DRIVERS
+ select DT_IDLE_STATES
help
Select this option to enable CPU idle driver for big.LITTLE based
ARM systems. Driver manages CPUs coordination through MCPM and
diff --git a/drivers/cpuidle/cpuidle-big_little.c b/drivers/cpuidle/cpuidle-big_little.c
index ef94c3b..85d09bc 100644
--- a/drivers/cpuidle/cpuidle-big_little.c
+++ b/drivers/cpuidle/cpuidle-big_little.c
@@ -24,6 +24,8 @@
#include <asm/smp_plat.h>
#include <asm/suspend.h>
+#include "dt_idle_states.h"
+
static int bl_enter_powerdown(struct cpuidle_device *dev,
struct cpuidle_driver *drv, int idx);
@@ -73,6 +75,12 @@ static struct cpuidle_driver bl_idle_little_driver = {
.state_count = 2,
};
+static const struct of_device_id bl_idle_state_match[] __initconst = {
+ { .compatible = "arm,idle-state",
+ .data = bl_enter_powerdown },
+ { },
+};
+
static struct cpuidle_driver bl_idle_big_driver = {
.name = "big_idle",
.owner = THIS_MODULE,
@@ -190,6 +198,17 @@ static int __init bl_idle_init(void)
if (ret)
goto out_uninit_little;
+ /* Start at index 1, index 0 standard WFI */
+ ret = dt_init_idle_driver(&bl_idle_big_driver, bl_idle_state_match, 1);
+ if (ret < 0)
+ goto out_uninit_big;
+
+ /* Start@index 1, index 0 standard WFI */
+ ret = dt_init_idle_driver(&bl_idle_little_driver,
+ bl_idle_state_match, 1);
+ if (ret < 0)
+ goto out_uninit_big;
+
ret = cpuidle_register(&bl_idle_little_driver, NULL);
if (ret)
goto out_uninit_big;
--
1.9.1
^ permalink raw reply related [flat|nested] 29+ messages in thread
* [PATCH v9 8/8] drivers: cpuidle: initialize Exynos driver through DT
2014-09-05 17:34 ` Lorenzo Pieralisi
@ 2014-09-05 17:34 ` Lorenzo Pieralisi
-1 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-05 17:34 UTC (permalink / raw)
To: linux-arm-kernel, linux-pm
Cc: devicetree, Lorenzo Pieralisi, Chander Kashyap, Kukjin Kim,
Mark Rutland, Sudeep Holla, Catalin Marinas, Will Deacon,
Charles Garcia Tobin, Nicolas Pitre, Rob Herring, Grant Likely,
Peter De Schrijver, Santosh Shilimkar, Daniel Lezcano,
Amit Kucheria, Vincent Guittot, Antti Miettinen, Stephen Boyd,
Kevin Hilman, Sebastian Capella, Mark Brown, Paul
With the introduction of DT based idle states, CPUidle drivers for
ARM can now initialize idle states data through properties in the device
tree.
This patch adds code to the Exynos CPUidle driver to dynamically
initialize idle states data through the updated device tree source
files.
Cc: Chander Kashyap <k.chander@samsung.com>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
arch/arm/boot/dts/exynos4210.dtsi | 11 +++++++++++
arch/arm/boot/dts/exynos5250.dtsi | 11 +++++++++++
drivers/cpuidle/Kconfig.arm | 1 +
drivers/cpuidle/cpuidle-exynos.c | 18 +++++++++++++++++-
4 files changed, 40 insertions(+), 1 deletion(-)
diff --git a/arch/arm/boot/dts/exynos4210.dtsi b/arch/arm/boot/dts/exynos4210.dtsi
index eab7c7b..69fd1a0 100644
--- a/arch/arm/boot/dts/exynos4210.dtsi
+++ b/arch/arm/boot/dts/exynos4210.dtsi
@@ -48,12 +48,23 @@
device_type = "cpu";
compatible = "arm,cortex-a9";
reg = <0x900>;
+ cpu-idle-states = <&CLUSTER_SLEEP_0>;
};
cpu@901 {
device_type = "cpu";
compatible = "arm,cortex-a9";
reg = <0x901>;
+ cpu-idle-states = <&CLUSTER_SLEEP_0>;
+ };
+
+ idle-states {
+ CLUSTER_SLEEP_0: cluster-sleep-0 {
+ compatible = "arm,idle-state";
+ entry-latency-us = <1000>;
+ exit-latency-us = <300>;
+ min-residency-us = <100000>;
+ };
};
};
diff --git a/arch/arm/boot/dts/exynos5250.dtsi b/arch/arm/boot/dts/exynos5250.dtsi
index 492e1ef..3a758ff 100644
--- a/arch/arm/boot/dts/exynos5250.dtsi
+++ b/arch/arm/boot/dts/exynos5250.dtsi
@@ -63,12 +63,23 @@
compatible = "arm,cortex-a15";
reg = <0>;
clock-frequency = <1700000000>;
+ cpu-idle-states = <&CLUSTER_SLEEP_0>;
};
cpu@1 {
device_type = "cpu";
compatible = "arm,cortex-a15";
reg = <1>;
clock-frequency = <1700000000>;
+ cpu-idle-states = <&CLUSTER_SLEEP_0>;
+ };
+
+ idle-states {
+ CLUSTER_SLEEP_0: cluster-sleep-0 {
+ compatible = "arm,idle-state";
+ entry-latency-us = <1000>;
+ exit-latency-us = <300>;
+ min-residency-us = <100000>;
+ };
};
};
diff --git a/drivers/cpuidle/Kconfig.arm b/drivers/cpuidle/Kconfig.arm
index e339c7f..04cc229 100644
--- a/drivers/cpuidle/Kconfig.arm
+++ b/drivers/cpuidle/Kconfig.arm
@@ -55,6 +55,7 @@ config ARM_AT91_CPUIDLE
config ARM_EXYNOS_CPUIDLE
bool "Cpu Idle Driver for the Exynos processors"
depends on ARCH_EXYNOS
+ select DT_IDLE_STATES
help
Select this to enable cpuidle for Exynos processors
diff --git a/drivers/cpuidle/cpuidle-exynos.c b/drivers/cpuidle/cpuidle-exynos.c
index ba9b34b..e66a426 100644
--- a/drivers/cpuidle/cpuidle-exynos.c
+++ b/drivers/cpuidle/cpuidle-exynos.c
@@ -18,6 +18,8 @@
#include <asm/suspend.h>
#include <asm/cpuidle.h>
+#include "dt_idle_states.h"
+
static void (*exynos_enter_aftr)(void);
static int exynos_enter_lowpower(struct cpuidle_device *dev,
@@ -56,13 +58,27 @@ static struct cpuidle_driver exynos_idle_driver = {
.safe_state_index = 0,
};
+static const struct of_device_id exynos_idle_state_match[] __initconst = {
+ { .compatible = "arm,idle-state",
+ .data = exynos_enter_lowpower },
+ { },
+};
+
static int exynos_cpuidle_probe(struct platform_device *pdev)
{
int ret;
+ struct cpuidle_driver *drv = &exynos_idle_driver;
exynos_enter_aftr = (void *)(pdev->dev.platform_data);
- ret = cpuidle_register(&exynos_idle_driver, NULL);
+ /* Start at index 1, index 0 standard WFI */
+ ret = dt_init_idle_driver(drv, exynos_idle_state_match, 1);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to initialize idle states\n");
+ return ret;
+ }
+
+ ret = cpuidle_register(drv, NULL);
if (ret) {
dev_err(&pdev->dev, "failed to register cpuidle driver\n");
return ret;
--
1.9.1
^ permalink raw reply related [flat|nested] 29+ messages in thread
* [PATCH v9 8/8] drivers: cpuidle: initialize Exynos driver through DT
@ 2014-09-05 17:34 ` Lorenzo Pieralisi
0 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-05 17:34 UTC (permalink / raw)
To: linux-arm-kernel
With the introduction of DT based idle states, CPUidle drivers for
ARM can now initialize idle states data through properties in the device
tree.
This patch adds code to the Exynos CPUidle driver to dynamically
initialize idle states data through the updated device tree source
files.
Cc: Chander Kashyap <k.chander@samsung.com>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
---
arch/arm/boot/dts/exynos4210.dtsi | 11 +++++++++++
arch/arm/boot/dts/exynos5250.dtsi | 11 +++++++++++
drivers/cpuidle/Kconfig.arm | 1 +
drivers/cpuidle/cpuidle-exynos.c | 18 +++++++++++++++++-
4 files changed, 40 insertions(+), 1 deletion(-)
diff --git a/arch/arm/boot/dts/exynos4210.dtsi b/arch/arm/boot/dts/exynos4210.dtsi
index eab7c7b..69fd1a0 100644
--- a/arch/arm/boot/dts/exynos4210.dtsi
+++ b/arch/arm/boot/dts/exynos4210.dtsi
@@ -48,12 +48,23 @@
device_type = "cpu";
compatible = "arm,cortex-a9";
reg = <0x900>;
+ cpu-idle-states = <&CLUSTER_SLEEP_0>;
};
cpu at 901 {
device_type = "cpu";
compatible = "arm,cortex-a9";
reg = <0x901>;
+ cpu-idle-states = <&CLUSTER_SLEEP_0>;
+ };
+
+ idle-states {
+ CLUSTER_SLEEP_0: cluster-sleep-0 {
+ compatible = "arm,idle-state";
+ entry-latency-us = <1000>;
+ exit-latency-us = <300>;
+ min-residency-us = <100000>;
+ };
};
};
diff --git a/arch/arm/boot/dts/exynos5250.dtsi b/arch/arm/boot/dts/exynos5250.dtsi
index 492e1ef..3a758ff 100644
--- a/arch/arm/boot/dts/exynos5250.dtsi
+++ b/arch/arm/boot/dts/exynos5250.dtsi
@@ -63,12 +63,23 @@
compatible = "arm,cortex-a15";
reg = <0>;
clock-frequency = <1700000000>;
+ cpu-idle-states = <&CLUSTER_SLEEP_0>;
};
cpu at 1 {
device_type = "cpu";
compatible = "arm,cortex-a15";
reg = <1>;
clock-frequency = <1700000000>;
+ cpu-idle-states = <&CLUSTER_SLEEP_0>;
+ };
+
+ idle-states {
+ CLUSTER_SLEEP_0: cluster-sleep-0 {
+ compatible = "arm,idle-state";
+ entry-latency-us = <1000>;
+ exit-latency-us = <300>;
+ min-residency-us = <100000>;
+ };
};
};
diff --git a/drivers/cpuidle/Kconfig.arm b/drivers/cpuidle/Kconfig.arm
index e339c7f..04cc229 100644
--- a/drivers/cpuidle/Kconfig.arm
+++ b/drivers/cpuidle/Kconfig.arm
@@ -55,6 +55,7 @@ config ARM_AT91_CPUIDLE
config ARM_EXYNOS_CPUIDLE
bool "Cpu Idle Driver for the Exynos processors"
depends on ARCH_EXYNOS
+ select DT_IDLE_STATES
help
Select this to enable cpuidle for Exynos processors
diff --git a/drivers/cpuidle/cpuidle-exynos.c b/drivers/cpuidle/cpuidle-exynos.c
index ba9b34b..e66a426 100644
--- a/drivers/cpuidle/cpuidle-exynos.c
+++ b/drivers/cpuidle/cpuidle-exynos.c
@@ -18,6 +18,8 @@
#include <asm/suspend.h>
#include <asm/cpuidle.h>
+#include "dt_idle_states.h"
+
static void (*exynos_enter_aftr)(void);
static int exynos_enter_lowpower(struct cpuidle_device *dev,
@@ -56,13 +58,27 @@ static struct cpuidle_driver exynos_idle_driver = {
.safe_state_index = 0,
};
+static const struct of_device_id exynos_idle_state_match[] __initconst = {
+ { .compatible = "arm,idle-state",
+ .data = exynos_enter_lowpower },
+ { },
+};
+
static int exynos_cpuidle_probe(struct platform_device *pdev)
{
int ret;
+ struct cpuidle_driver *drv = &exynos_idle_driver;
exynos_enter_aftr = (void *)(pdev->dev.platform_data);
- ret = cpuidle_register(&exynos_idle_driver, NULL);
+ /* Start at index 1, index 0 standard WFI */
+ ret = dt_init_idle_driver(drv, exynos_idle_state_match, 1);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to initialize idle states\n");
+ return ret;
+ }
+
+ ret = cpuidle_register(drv, NULL);
if (ret) {
dev_err(&pdev->dev, "failed to register cpuidle driver\n");
return ret;
--
1.9.1
^ permalink raw reply related [flat|nested] 29+ messages in thread
* Re: [PATCH v9 5/8] drivers: cpuidle: implement DT based idle states infrastructure
2014-09-05 17:34 ` Lorenzo Pieralisi
(?)
@ 2014-09-05 20:00 ` Kevin Hilman
2014-09-05 21:29 ` Lorenzo Pieralisi
-1 siblings, 1 reply; 29+ messages in thread
From: Kevin Hilman @ 2014-09-05 20:00 UTC (permalink / raw)
To: Lorenzo Pieralisi
Cc: linux-arm-kernel, linux-pm, devicetree, Mark Rutland,
Sudeep Holla, Catalin Marinas, Will Deacon, Charles Garcia Tobin,
Nicolas Pitre, Rob Herring, Grant Likely, Peter De Schrijver,
Santosh Shilimkar, Daniel Lezcano, Amit Kucheria, Vincent Guittot,
Antti Miettinen, Stephen Boyd, Sebastian Capella, Mark Brown,
Paul Walmsley, Chander Kashyap, Geoff Levand,
Bartlomiej Zolnierkiewicz, Ashwin Chaugule <ashwin.chau
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> writes:
> On most common ARM systems, the low-power states a CPU can be put into are
> not discoverable in HW and require device tree bindings to describe
> power down suspend operations and idle states parameters.
>
> In order to enable DT based idle states and configure idle drivers, this
> patch implements the bulk infrastructure required to parse the device tree
> idle states bindings and initialize the corresponding CPUidle driver states
> data.
>
> The parsing API accepts a start index that defines the first idle state
> that should be initialized by the parsing code in order to give new and
> legacy driver flexibility over which states should be parsed using the
> new DT mechanism.
>
> The idle states node(s) is obtained from the phandle list of the first cpu
> in the driver cpumask; the kernel checks that the idle state node phandle
> is the same for all CPUs in the driver cpumask before declaring the idle state
> as valid and start parsing its content.
>
> The idle state enter function pointer is initialized through DT match
> structures passed in by the CPUidle driver, so that ARM legacy code can
> cope with platform specific idle entry method based on compatible
> string matching and the code used to initialize the enter function pointer
> can be moved to the DT generic layer.
>
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
[...]
> + idle_state->flags = CPUIDLE_FLAG_TIME_VALID;
> + if (of_property_read_bool(state_node, "local-timer-stop"))
> + idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP;
> + /*
> + * TODO:
> + * replace with kstrdup and pointer assignment when name
> + * and desc become string pointers
> + */
> + strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN - 1);
> + strncpy(idle_state->desc, state_node->name, CPUIDLE_DESC_LEN - 1);
This is a very minor concern, and shouldn't hold back this series,
but...
I was playing with this series in order to test out the qcom cpuidle
driver from Lina, and noticed that the state name and descriptions were
not terribly helpful:
/sys/devices/system/cpu/cpu0/cpuidle # cat state?/name
cpu-idle-state-
cpu-idle-state-
/sys/devices/system/cpu/cpu0/cpuidle # cat state?/desc
cpu-idle-state-0
cpu-idle-state-1
Turns out these strings come from the node name itself, and truncated in
the case of state->name, but this can be fixed in the DTS itself (c.f.
reply to Lina's driver.)
However, seeing that the node name is used to populate both the
state->name and ->, made me wonder if there should better way to set the
state->desc field to a more useful string. Tools like powertop actually
use that field and it can be quite useful.
Kevin
^ permalink raw reply [flat|nested] 29+ messages in thread
* Re: [PATCH v9 5/8] drivers: cpuidle: implement DT based idle states infrastructure
2014-09-05 20:00 ` Kevin Hilman
@ 2014-09-05 21:29 ` Lorenzo Pieralisi
0 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-05 21:29 UTC (permalink / raw)
To: Kevin Hilman
Cc: linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org,
devicetree@vger.kernel.org, Mark Rutland, Sudeep Holla,
Catalin Marinas, Will Deacon, Charles Garcia-Tobin, Nicolas Pitre,
Rob Herring, grant.likely@linaro.org, Peter De Schrijver,
Santosh Shilimkar, Daniel Lezcano, Amit Kucheria, Vincent Guittot,
Antti Miettinen, Stephen Boyd, Sebastian Capella, Mark Brown
On Fri, Sep 05, 2014 at 09:00:52PM +0100, Kevin Hilman wrote:
> Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> writes:
>
> > On most common ARM systems, the low-power states a CPU can be put into are
> > not discoverable in HW and require device tree bindings to describe
> > power down suspend operations and idle states parameters.
> >
> > In order to enable DT based idle states and configure idle drivers, this
> > patch implements the bulk infrastructure required to parse the device tree
> > idle states bindings and initialize the corresponding CPUidle driver states
> > data.
> >
> > The parsing API accepts a start index that defines the first idle state
> > that should be initialized by the parsing code in order to give new and
> > legacy driver flexibility over which states should be parsed using the
> > new DT mechanism.
> >
> > The idle states node(s) is obtained from the phandle list of the first cpu
> > in the driver cpumask; the kernel checks that the idle state node phandle
> > is the same for all CPUs in the driver cpumask before declaring the idle state
> > as valid and start parsing its content.
> >
> > The idle state enter function pointer is initialized through DT match
> > structures passed in by the CPUidle driver, so that ARM legacy code can
> > cope with platform specific idle entry method based on compatible
> > string matching and the code used to initialize the enter function pointer
> > can be moved to the DT generic layer.
> >
> > Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> > Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
>
> [...]
>
> > + idle_state->flags = CPUIDLE_FLAG_TIME_VALID;
> > + if (of_property_read_bool(state_node, "local-timer-stop"))
> > + idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP;
> > + /*
> > + * TODO:
> > + * replace with kstrdup and pointer assignment when name
> > + * and desc become string pointers
> > + */
> > + strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN - 1);
> > + strncpy(idle_state->desc, state_node->name, CPUIDLE_DESC_LEN - 1);
>
> This is a very minor concern, and shouldn't hold back this series,
> but...
>
> I was playing with this series in order to test out the qcom cpuidle
> driver from Lina, and noticed that the state name and descriptions were
> not terribly helpful:
>
> /sys/devices/system/cpu/cpu0/cpuidle # cat state?/name
> cpu-idle-state-
> cpu-idle-state-
> /sys/devices/system/cpu/cpu0/cpuidle # cat state?/desc
> cpu-idle-state-0
> cpu-idle-state-1
>
> Turns out these strings come from the node name itself, and truncated in
> the case of state->name, but this can be fixed in the DTS itself (c.f.
> reply to Lina's driver.)
>
> However, seeing that the node name is used to populate both the
> state->name and ->, made me wonder if there should better way to set the
> state->desc field to a more useful string. Tools like powertop actually
> use that field and it can be quite useful.
Well, the truncation problem will be solved when those strings will be
kdup'ed, so for the name I think there is not a problem, copying the
state node is fine waiting for those strings to become pointers.
For desc, there are four options:
(1) enumerating idle states (but that's worse than copying the name into
desc since on ARM idle-state{1,2,3...} means nothing)
(2) copying the idle state node compatible string into desc
(3) Add an optional property to the DT bindings to describe the state
(4) Leave code as it is
(3) I am not extremely keen at this stage to re-patch the DT bindings,
it has been an awful lot of work to make everyone agree so I would avoid
any changes, I hope you understand (and I am not even sure DT maintainers
would accept that, so even less keen on changing the DT bindings at this
stage).
(2) I am not sure it will clarify the description much.
(1) I would rule it out. So either we accept that the name can be
extended in length (that's going to be the case since we will
dynamically allocate the string so there will be no truncation, to
a reasonable extent) so (4) is fine, or we merge this code and I
will take care of pushing for (3) in a separate patch and copy the resulting
description into desc (if that change does not get NACK'ed).
I would really want to see this code in the mailine asap since it is
groundwork for all future CPUidle generalisation, I hope that what I am
saying above is acceptable, please let me know what you think.
Lorenzo
^ permalink raw reply [flat|nested] 29+ messages in thread
* [PATCH v9 5/8] drivers: cpuidle: implement DT based idle states infrastructure
@ 2014-09-05 21:29 ` Lorenzo Pieralisi
0 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-05 21:29 UTC (permalink / raw)
To: linux-arm-kernel
On Fri, Sep 05, 2014 at 09:00:52PM +0100, Kevin Hilman wrote:
> Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> writes:
>
> > On most common ARM systems, the low-power states a CPU can be put into are
> > not discoverable in HW and require device tree bindings to describe
> > power down suspend operations and idle states parameters.
> >
> > In order to enable DT based idle states and configure idle drivers, this
> > patch implements the bulk infrastructure required to parse the device tree
> > idle states bindings and initialize the corresponding CPUidle driver states
> > data.
> >
> > The parsing API accepts a start index that defines the first idle state
> > that should be initialized by the parsing code in order to give new and
> > legacy driver flexibility over which states should be parsed using the
> > new DT mechanism.
> >
> > The idle states node(s) is obtained from the phandle list of the first cpu
> > in the driver cpumask; the kernel checks that the idle state node phandle
> > is the same for all CPUs in the driver cpumask before declaring the idle state
> > as valid and start parsing its content.
> >
> > The idle state enter function pointer is initialized through DT match
> > structures passed in by the CPUidle driver, so that ARM legacy code can
> > cope with platform specific idle entry method based on compatible
> > string matching and the code used to initialize the enter function pointer
> > can be moved to the DT generic layer.
> >
> > Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> > Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
>
> [...]
>
> > + idle_state->flags = CPUIDLE_FLAG_TIME_VALID;
> > + if (of_property_read_bool(state_node, "local-timer-stop"))
> > + idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP;
> > + /*
> > + * TODO:
> > + * replace with kstrdup and pointer assignment when name
> > + * and desc become string pointers
> > + */
> > + strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN - 1);
> > + strncpy(idle_state->desc, state_node->name, CPUIDLE_DESC_LEN - 1);
>
> This is a very minor concern, and shouldn't hold back this series,
> but...
>
> I was playing with this series in order to test out the qcom cpuidle
> driver from Lina, and noticed that the state name and descriptions were
> not terribly helpful:
>
> /sys/devices/system/cpu/cpu0/cpuidle # cat state?/name
> cpu-idle-state-
> cpu-idle-state-
> /sys/devices/system/cpu/cpu0/cpuidle # cat state?/desc
> cpu-idle-state-0
> cpu-idle-state-1
>
> Turns out these strings come from the node name itself, and truncated in
> the case of state->name, but this can be fixed in the DTS itself (c.f.
> reply to Lina's driver.)
>
> However, seeing that the node name is used to populate both the
> state->name and ->, made me wonder if there should better way to set the
> state->desc field to a more useful string. Tools like powertop actually
> use that field and it can be quite useful.
Well, the truncation problem will be solved when those strings will be
kdup'ed, so for the name I think there is not a problem, copying the
state node is fine waiting for those strings to become pointers.
For desc, there are four options:
(1) enumerating idle states (but that's worse than copying the name into
desc since on ARM idle-state{1,2,3...} means nothing)
(2) copying the idle state node compatible string into desc
(3) Add an optional property to the DT bindings to describe the state
(4) Leave code as it is
(3) I am not extremely keen at this stage to re-patch the DT bindings,
it has been an awful lot of work to make everyone agree so I would avoid
any changes, I hope you understand (and I am not even sure DT maintainers
would accept that, so even less keen on changing the DT bindings at this
stage).
(2) I am not sure it will clarify the description much.
(1) I would rule it out. So either we accept that the name can be
extended in length (that's going to be the case since we will
dynamically allocate the string so there will be no truncation, to
a reasonable extent) so (4) is fine, or we merge this code and I
will take care of pushing for (3) in a separate patch and copy the resulting
description into desc (if that change does not get NACK'ed).
I would really want to see this code in the mailine asap since it is
groundwork for all future CPUidle generalisation, I hope that what I am
saying above is acceptable, please let me know what you think.
Lorenzo
^ permalink raw reply [flat|nested] 29+ messages in thread
* Re: [PATCH v9 5/8] drivers: cpuidle: implement DT based idle states infrastructure
2014-09-05 21:29 ` Lorenzo Pieralisi
@ 2014-09-05 21:36 ` Mark Brown
-1 siblings, 0 replies; 29+ messages in thread
From: Mark Brown @ 2014-09-05 21:36 UTC (permalink / raw)
To: Lorenzo Pieralisi
Cc: Kevin Hilman, linux-arm-kernel@lists.infradead.org,
linux-pm@vger.kernel.org, devicetree@vger.kernel.org,
Mark Rutland, Sudeep Holla, Catalin Marinas, Will Deacon,
Charles Garcia-Tobin, Nicolas Pitre, Rob Herring,
grant.likely@linaro.org, Peter De Schrijver, Santosh Shilimkar,
Daniel Lezcano, Amit Kucheria, Vincent Guittot, Antti Miettinen,
Stephen Boyd, Sebastian Capella <sebcape@
[-- Attachment #1: Type: text/plain, Size: 679 bytes --]
On Fri, Sep 05, 2014 at 10:29:08PM +0100, Lorenzo Pieralisi wrote:
> On Fri, Sep 05, 2014 at 09:00:52PM +0100, Kevin Hilman wrote:
> (3) Add an optional property to the DT bindings to describe the state
> (3) I am not extremely keen at this stage to re-patch the DT bindings,
> it has been an awful lot of work to make everyone agree so I would avoid
> any changes, I hope you understand (and I am not even sure DT maintainers
> would accept that, so even less keen on changing the DT bindings at this
> stage).
Just do it as an incremental patch if you're worried - we've got
precendents for this like regulator-name which exists solely to make
diagnostics more descriptive.
[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 819 bytes --]
^ permalink raw reply [flat|nested] 29+ messages in thread
* [PATCH v9 5/8] drivers: cpuidle: implement DT based idle states infrastructure
@ 2014-09-05 21:36 ` Mark Brown
0 siblings, 0 replies; 29+ messages in thread
From: Mark Brown @ 2014-09-05 21:36 UTC (permalink / raw)
To: linux-arm-kernel
On Fri, Sep 05, 2014 at 10:29:08PM +0100, Lorenzo Pieralisi wrote:
> On Fri, Sep 05, 2014 at 09:00:52PM +0100, Kevin Hilman wrote:
> (3) Add an optional property to the DT bindings to describe the state
> (3) I am not extremely keen at this stage to re-patch the DT bindings,
> it has been an awful lot of work to make everyone agree so I would avoid
> any changes, I hope you understand (and I am not even sure DT maintainers
> would accept that, so even less keen on changing the DT bindings at this
> stage).
Just do it as an incremental patch if you're worried - we've got
precendents for this like regulator-name which exists solely to make
diagnostics more descriptive.
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^ permalink raw reply [flat|nested] 29+ messages in thread
* Re: [PATCH v9 5/8] drivers: cpuidle: implement DT based idle states infrastructure
2014-09-05 21:29 ` Lorenzo Pieralisi
@ 2014-09-08 15:58 ` Kevin Hilman
-1 siblings, 0 replies; 29+ messages in thread
From: Kevin Hilman @ 2014-09-08 15:58 UTC (permalink / raw)
To: Lorenzo Pieralisi
Cc: linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org,
devicetree@vger.kernel.org, Mark Rutland, Sudeep Holla,
Catalin Marinas, Will Deacon, Charles Garcia-Tobin, Nicolas Pitre,
Rob Herring, grant.likely@linaro.org, Peter De Schrijver,
Santosh Shilimkar, Daniel Lezcano, Amit Kucheria, Vincent Guittot,
Antti Miettinen, Stephen Boyd, Sebastian Capella,
Mark Brown <broonie>
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> writes:
> On Fri, Sep 05, 2014 at 09:00:52PM +0100, Kevin Hilman wrote:
>> Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> writes:
>>
>> > On most common ARM systems, the low-power states a CPU can be put into are
>> > not discoverable in HW and require device tree bindings to describe
>> > power down suspend operations and idle states parameters.
>> >
>> > In order to enable DT based idle states and configure idle drivers, this
>> > patch implements the bulk infrastructure required to parse the device tree
>> > idle states bindings and initialize the corresponding CPUidle driver states
>> > data.
>> >
>> > The parsing API accepts a start index that defines the first idle state
>> > that should be initialized by the parsing code in order to give new and
>> > legacy driver flexibility over which states should be parsed using the
>> > new DT mechanism.
>> >
>> > The idle states node(s) is obtained from the phandle list of the first cpu
>> > in the driver cpumask; the kernel checks that the idle state node phandle
>> > is the same for all CPUs in the driver cpumask before declaring the idle state
>> > as valid and start parsing its content.
>> >
>> > The idle state enter function pointer is initialized through DT match
>> > structures passed in by the CPUidle driver, so that ARM legacy code can
>> > cope with platform specific idle entry method based on compatible
>> > string matching and the code used to initialize the enter function pointer
>> > can be moved to the DT generic layer.
>> >
>> > Acked-by: Catalin Marinas <catalin.marinas@arm.com>
>> > Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
>> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
>>
>> [...]
>>
>> > + idle_state->flags = CPUIDLE_FLAG_TIME_VALID;
>> > + if (of_property_read_bool(state_node, "local-timer-stop"))
>> > + idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP;
>> > + /*
>> > + * TODO:
>> > + * replace with kstrdup and pointer assignment when name
>> > + * and desc become string pointers
>> > + */
>> > + strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN - 1);
>> > + strncpy(idle_state->desc, state_node->name, CPUIDLE_DESC_LEN - 1);
>>
>> This is a very minor concern, and shouldn't hold back this series,
>> but...
>>
>> I was playing with this series in order to test out the qcom cpuidle
>> driver from Lina, and noticed that the state name and descriptions were
>> not terribly helpful:
>>
>> /sys/devices/system/cpu/cpu0/cpuidle # cat state?/name
>> cpu-idle-state-
>> cpu-idle-state-
>> /sys/devices/system/cpu/cpu0/cpuidle # cat state?/desc
>> cpu-idle-state-0
>> cpu-idle-state-1
>>
>> Turns out these strings come from the node name itself, and truncated in
>> the case of state->name, but this can be fixed in the DTS itself (c.f.
>> reply to Lina's driver.)
>>
>> However, seeing that the node name is used to populate both the
>> state->name and ->, made me wonder if there should better way to set the
>> state->desc field to a more useful string. Tools like powertop actually
>> use that field and it can be quite useful.
>
> Well, the truncation problem will be solved when those strings will be
> kdup'ed, so for the name I think there is not a problem, copying the
> state node is fine waiting for those strings to become pointers.
>
> For desc, there are four options:
>
> (1) enumerating idle states (but that's worse than copying the name into
> desc since on ARM idle-state{1,2,3...} means nothing)
> (2) copying the idle state node compatible string into desc
> (3) Add an optional property to the DT bindings to describe the state
> (4) Leave code as it is
>
> (3) I am not extremely keen at this stage to re-patch the DT bindings,
> it has been an awful lot of work to make everyone agree so I would avoid
> any changes, I hope you understand (and I am not even sure DT maintainers
> would accept that, so even less keen on changing the DT bindings at this
> stage).
>
> (2) I am not sure it will clarify the description much.
>
> (1) I would rule it out. So either we accept that the name can be
> extended in length (that's going to be the case since we will
> dynamically allocate the string so there will be no truncation, to
> a reasonable extent) so (4) is fine, or we merge this code and I
> will take care of pushing for (3) in a separate patch and copy the resulting
> description into desc (if that change does not get NACK'ed).
>
> I would really want to see this code in the mailine asap since it is
> groundwork for all future CPUidle generalisation, I hope that what I am
> saying above is acceptable, please let me know what you think.
Agreed, as I stated when I rasied this issue, it's a very minor concern
and I don't think it should hold back this series.
After this series is merged, I think approach (3) is probably the best
and should be done as a follow-up patch/series.
Kevin
^ permalink raw reply [flat|nested] 29+ messages in thread
* [PATCH v9 5/8] drivers: cpuidle: implement DT based idle states infrastructure
@ 2014-09-08 15:58 ` Kevin Hilman
0 siblings, 0 replies; 29+ messages in thread
From: Kevin Hilman @ 2014-09-08 15:58 UTC (permalink / raw)
To: linux-arm-kernel
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> writes:
> On Fri, Sep 05, 2014 at 09:00:52PM +0100, Kevin Hilman wrote:
>> Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> writes:
>>
>> > On most common ARM systems, the low-power states a CPU can be put into are
>> > not discoverable in HW and require device tree bindings to describe
>> > power down suspend operations and idle states parameters.
>> >
>> > In order to enable DT based idle states and configure idle drivers, this
>> > patch implements the bulk infrastructure required to parse the device tree
>> > idle states bindings and initialize the corresponding CPUidle driver states
>> > data.
>> >
>> > The parsing API accepts a start index that defines the first idle state
>> > that should be initialized by the parsing code in order to give new and
>> > legacy driver flexibility over which states should be parsed using the
>> > new DT mechanism.
>> >
>> > The idle states node(s) is obtained from the phandle list of the first cpu
>> > in the driver cpumask; the kernel checks that the idle state node phandle
>> > is the same for all CPUs in the driver cpumask before declaring the idle state
>> > as valid and start parsing its content.
>> >
>> > The idle state enter function pointer is initialized through DT match
>> > structures passed in by the CPUidle driver, so that ARM legacy code can
>> > cope with platform specific idle entry method based on compatible
>> > string matching and the code used to initialize the enter function pointer
>> > can be moved to the DT generic layer.
>> >
>> > Acked-by: Catalin Marinas <catalin.marinas@arm.com>
>> > Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
>> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
>>
>> [...]
>>
>> > + idle_state->flags = CPUIDLE_FLAG_TIME_VALID;
>> > + if (of_property_read_bool(state_node, "local-timer-stop"))
>> > + idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP;
>> > + /*
>> > + * TODO:
>> > + * replace with kstrdup and pointer assignment when name
>> > + * and desc become string pointers
>> > + */
>> > + strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN - 1);
>> > + strncpy(idle_state->desc, state_node->name, CPUIDLE_DESC_LEN - 1);
>>
>> This is a very minor concern, and shouldn't hold back this series,
>> but...
>>
>> I was playing with this series in order to test out the qcom cpuidle
>> driver from Lina, and noticed that the state name and descriptions were
>> not terribly helpful:
>>
>> /sys/devices/system/cpu/cpu0/cpuidle # cat state?/name
>> cpu-idle-state-
>> cpu-idle-state-
>> /sys/devices/system/cpu/cpu0/cpuidle # cat state?/desc
>> cpu-idle-state-0
>> cpu-idle-state-1
>>
>> Turns out these strings come from the node name itself, and truncated in
>> the case of state->name, but this can be fixed in the DTS itself (c.f.
>> reply to Lina's driver.)
>>
>> However, seeing that the node name is used to populate both the
>> state->name and ->, made me wonder if there should better way to set the
>> state->desc field to a more useful string. Tools like powertop actually
>> use that field and it can be quite useful.
>
> Well, the truncation problem will be solved when those strings will be
> kdup'ed, so for the name I think there is not a problem, copying the
> state node is fine waiting for those strings to become pointers.
>
> For desc, there are four options:
>
> (1) enumerating idle states (but that's worse than copying the name into
> desc since on ARM idle-state{1,2,3...} means nothing)
> (2) copying the idle state node compatible string into desc
> (3) Add an optional property to the DT bindings to describe the state
> (4) Leave code as it is
>
> (3) I am not extremely keen at this stage to re-patch the DT bindings,
> it has been an awful lot of work to make everyone agree so I would avoid
> any changes, I hope you understand (and I am not even sure DT maintainers
> would accept that, so even less keen on changing the DT bindings at this
> stage).
>
> (2) I am not sure it will clarify the description much.
>
> (1) I would rule it out. So either we accept that the name can be
> extended in length (that's going to be the case since we will
> dynamically allocate the string so there will be no truncation, to
> a reasonable extent) so (4) is fine, or we merge this code and I
> will take care of pushing for (3) in a separate patch and copy the resulting
> description into desc (if that change does not get NACK'ed).
>
> I would really want to see this code in the mailine asap since it is
> groundwork for all future CPUidle generalisation, I hope that what I am
> saying above is acceptable, please let me know what you think.
Agreed, as I stated when I rasied this issue, it's a very minor concern
and I don't think it should hold back this series.
After this series is merged, I think approach (3) is probably the best
and should be done as a follow-up patch/series.
Kevin
^ permalink raw reply [flat|nested] 29+ messages in thread
* Re: [PATCH v9 6/8] drivers: cpuidle: CPU idle ARM64 driver
2014-09-05 17:34 ` Lorenzo Pieralisi
@ 2014-09-08 16:08 ` Catalin Marinas
-1 siblings, 0 replies; 29+ messages in thread
From: Catalin Marinas @ 2014-09-08 16:08 UTC (permalink / raw)
To: Daniel Lezcano
Cc: Lorenzo Pieralisi, linux-arm-kernel@lists.infradead.org,
linux-pm@vger.kernel.org, devicetree@vger.kernel.org,
Mark Rutland, Sudeep Holla, Will Deacon, Charles Garcia-Tobin,
Nicolas Pitre, Rob Herring, grant.likely@linaro.org,
Peter De Schrijver, Santosh Shilimkar, Amit Kucheria,
Vincent Guittot, Antti Miettinen, Stephen Boyd, Kevin Hilman,
Sebastian Capella, Mark Brown
On Fri, Sep 05, 2014 at 06:34:55PM +0100, Lorenzo Pieralisi wrote:
> This patch implements a generic CPU idle driver for ARM64 machines.
>
> It relies on the DT idle states infrastructure to initialize idle
> states count and respective parameters. Current code assumes the driver
> is managing idle states on all possible CPUs but can be easily
> generalized to support heterogenous systems and build cpumasks at
> runtime using MIDRs or DT cpu nodes compatible properties.
>
> The driver relies on the arm64 CPU operations to call the idle
> initialization hook used to parse and save suspend back-end specific
> idle states information upon probing.
>
> Idle state index 0 is always initialized as a simple wfi state, ie always
> considered present and functional on all ARM64 platforms.
>
> Idle state indices higher than 0 trigger idle state entry by calling
> the cpu_suspend function, that triggers the suspend operation through
> the CPU operations suspend back-end hook. cpu_suspend passes the idle
> state index as a parameter so that the CPU operations suspend back-end
> can retrieve the required idle state data by using the idle state
> index to execute a look-up on its internal data structures.
>
> Reviewed-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> ---
> drivers/cpuidle/Kconfig | 5 ++
> drivers/cpuidle/Kconfig.arm64 | 14 +++++
> drivers/cpuidle/Makefile | 4 ++
> drivers/cpuidle/cpuidle-arm64.c | 133 ++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 156 insertions(+)
> create mode 100644 drivers/cpuidle/Kconfig.arm64
> create mode 100644 drivers/cpuidle/cpuidle-arm64.c
Daniel, do you have any preference for how this patch should go in? You
can either ack it so that I can take it via the arm64 tree or you take
it separately (though it doesn't make sense on its own without the arm64
infrastructure in place, we need a bit of synchronisation but it's not
something difficult).
Thanks.
--
Catalin
^ permalink raw reply [flat|nested] 29+ messages in thread
* [PATCH v9 6/8] drivers: cpuidle: CPU idle ARM64 driver
@ 2014-09-08 16:08 ` Catalin Marinas
0 siblings, 0 replies; 29+ messages in thread
From: Catalin Marinas @ 2014-09-08 16:08 UTC (permalink / raw)
To: linux-arm-kernel
On Fri, Sep 05, 2014 at 06:34:55PM +0100, Lorenzo Pieralisi wrote:
> This patch implements a generic CPU idle driver for ARM64 machines.
>
> It relies on the DT idle states infrastructure to initialize idle
> states count and respective parameters. Current code assumes the driver
> is managing idle states on all possible CPUs but can be easily
> generalized to support heterogenous systems and build cpumasks at
> runtime using MIDRs or DT cpu nodes compatible properties.
>
> The driver relies on the arm64 CPU operations to call the idle
> initialization hook used to parse and save suspend back-end specific
> idle states information upon probing.
>
> Idle state index 0 is always initialized as a simple wfi state, ie always
> considered present and functional on all ARM64 platforms.
>
> Idle state indices higher than 0 trigger idle state entry by calling
> the cpu_suspend function, that triggers the suspend operation through
> the CPU operations suspend back-end hook. cpu_suspend passes the idle
> state index as a parameter so that the CPU operations suspend back-end
> can retrieve the required idle state data by using the idle state
> index to execute a look-up on its internal data structures.
>
> Reviewed-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> ---
> drivers/cpuidle/Kconfig | 5 ++
> drivers/cpuidle/Kconfig.arm64 | 14 +++++
> drivers/cpuidle/Makefile | 4 ++
> drivers/cpuidle/cpuidle-arm64.c | 133 ++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 156 insertions(+)
> create mode 100644 drivers/cpuidle/Kconfig.arm64
> create mode 100644 drivers/cpuidle/cpuidle-arm64.c
Daniel, do you have any preference for how this patch should go in? You
can either ack it so that I can take it via the arm64 tree or you take
it separately (though it doesn't make sense on its own without the arm64
infrastructure in place, we need a bit of synchronisation but it's not
something difficult).
Thanks.
--
Catalin
^ permalink raw reply [flat|nested] 29+ messages in thread
* Re: [PATCH v9 5/8] drivers: cpuidle: implement DT based idle states infrastructure
2014-09-08 15:58 ` Kevin Hilman
@ 2014-09-09 15:51 ` Lorenzo Pieralisi
-1 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-09 15:51 UTC (permalink / raw)
To: Kevin Hilman
Cc: linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org,
devicetree@vger.kernel.org, Mark Rutland, Sudeep Holla,
Catalin Marinas, Will Deacon, Charles Garcia-Tobin, Nicolas Pitre,
Rob Herring, grant.likely@linaro.org, Peter De Schrijver,
Santosh Shilimkar, Daniel Lezcano, Amit Kucheria, Vincent Guittot,
Antti Miettinen, Stephen Boyd, Sebastian Capella, Mark Brown
On Mon, Sep 08, 2014 at 04:58:53PM +0100, Kevin Hilman wrote:
> Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> writes:
>
> > On Fri, Sep 05, 2014 at 09:00:52PM +0100, Kevin Hilman wrote:
> >> Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> writes:
> >>
> >> > On most common ARM systems, the low-power states a CPU can be put into are
> >> > not discoverable in HW and require device tree bindings to describe
> >> > power down suspend operations and idle states parameters.
> >> >
> >> > In order to enable DT based idle states and configure idle drivers, this
> >> > patch implements the bulk infrastructure required to parse the device tree
> >> > idle states bindings and initialize the corresponding CPUidle driver states
> >> > data.
> >> >
> >> > The parsing API accepts a start index that defines the first idle state
> >> > that should be initialized by the parsing code in order to give new and
> >> > legacy driver flexibility over which states should be parsed using the
> >> > new DT mechanism.
> >> >
> >> > The idle states node(s) is obtained from the phandle list of the first cpu
> >> > in the driver cpumask; the kernel checks that the idle state node phandle
> >> > is the same for all CPUs in the driver cpumask before declaring the idle state
> >> > as valid and start parsing its content.
> >> >
> >> > The idle state enter function pointer is initialized through DT match
> >> > structures passed in by the CPUidle driver, so that ARM legacy code can
> >> > cope with platform specific idle entry method based on compatible
> >> > string matching and the code used to initialize the enter function pointer
> >> > can be moved to the DT generic layer.
> >> >
> >> > Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> >> > Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
> >> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> >>
> >> [...]
> >>
> >> > + idle_state->flags = CPUIDLE_FLAG_TIME_VALID;
> >> > + if (of_property_read_bool(state_node, "local-timer-stop"))
> >> > + idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP;
> >> > + /*
> >> > + * TODO:
> >> > + * replace with kstrdup and pointer assignment when name
> >> > + * and desc become string pointers
> >> > + */
> >> > + strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN - 1);
> >> > + strncpy(idle_state->desc, state_node->name, CPUIDLE_DESC_LEN - 1);
> >>
> >> This is a very minor concern, and shouldn't hold back this series,
> >> but...
> >>
> >> I was playing with this series in order to test out the qcom cpuidle
> >> driver from Lina, and noticed that the state name and descriptions were
> >> not terribly helpful:
> >>
> >> /sys/devices/system/cpu/cpu0/cpuidle # cat state?/name
> >> cpu-idle-state-
> >> cpu-idle-state-
> >> /sys/devices/system/cpu/cpu0/cpuidle # cat state?/desc
> >> cpu-idle-state-0
> >> cpu-idle-state-1
> >>
> >> Turns out these strings come from the node name itself, and truncated in
> >> the case of state->name, but this can be fixed in the DTS itself (c.f.
> >> reply to Lina's driver.)
> >>
> >> However, seeing that the node name is used to populate both the
> >> state->name and ->, made me wonder if there should better way to set the
> >> state->desc field to a more useful string. Tools like powertop actually
> >> use that field and it can be quite useful.
> >
> > Well, the truncation problem will be solved when those strings will be
> > kdup'ed, so for the name I think there is not a problem, copying the
> > state node is fine waiting for those strings to become pointers.
> >
> > For desc, there are four options:
> >
> > (1) enumerating idle states (but that's worse than copying the name into
> > desc since on ARM idle-state{1,2,3...} means nothing)
> > (2) copying the idle state node compatible string into desc
> > (3) Add an optional property to the DT bindings to describe the state
> > (4) Leave code as it is
> >
> > (3) I am not extremely keen at this stage to re-patch the DT bindings,
> > it has been an awful lot of work to make everyone agree so I would avoid
> > any changes, I hope you understand (and I am not even sure DT maintainers
> > would accept that, so even less keen on changing the DT bindings at this
> > stage).
> >
> > (2) I am not sure it will clarify the description much.
> >
> > (1) I would rule it out. So either we accept that the name can be
> > extended in length (that's going to be the case since we will
> > dynamically allocate the string so there will be no truncation, to
> > a reasonable extent) so (4) is fine, or we merge this code and I
> > will take care of pushing for (3) in a separate patch and copy the resulting
> > description into desc (if that change does not get NACK'ed).
> >
> > I would really want to see this code in the mailine asap since it is
> > groundwork for all future CPUidle generalisation, I hope that what I am
> > saying above is acceptable, please let me know what you think.
>
> Agreed, as I stated when I rasied this issue, it's a very minor concern
> and I don't think it should hold back this series.
>
> After this series is merged, I think approach (3) is probably the best
> and should be done as a follow-up patch/series.
I agree and that's what I will do, thank you Kevin (and Mark).
Lorenzo
^ permalink raw reply [flat|nested] 29+ messages in thread
* [PATCH v9 5/8] drivers: cpuidle: implement DT based idle states infrastructure
@ 2014-09-09 15:51 ` Lorenzo Pieralisi
0 siblings, 0 replies; 29+ messages in thread
From: Lorenzo Pieralisi @ 2014-09-09 15:51 UTC (permalink / raw)
To: linux-arm-kernel
On Mon, Sep 08, 2014 at 04:58:53PM +0100, Kevin Hilman wrote:
> Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> writes:
>
> > On Fri, Sep 05, 2014 at 09:00:52PM +0100, Kevin Hilman wrote:
> >> Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> writes:
> >>
> >> > On most common ARM systems, the low-power states a CPU can be put into are
> >> > not discoverable in HW and require device tree bindings to describe
> >> > power down suspend operations and idle states parameters.
> >> >
> >> > In order to enable DT based idle states and configure idle drivers, this
> >> > patch implements the bulk infrastructure required to parse the device tree
> >> > idle states bindings and initialize the corresponding CPUidle driver states
> >> > data.
> >> >
> >> > The parsing API accepts a start index that defines the first idle state
> >> > that should be initialized by the parsing code in order to give new and
> >> > legacy driver flexibility over which states should be parsed using the
> >> > new DT mechanism.
> >> >
> >> > The idle states node(s) is obtained from the phandle list of the first cpu
> >> > in the driver cpumask; the kernel checks that the idle state node phandle
> >> > is the same for all CPUs in the driver cpumask before declaring the idle state
> >> > as valid and start parsing its content.
> >> >
> >> > The idle state enter function pointer is initialized through DT match
> >> > structures passed in by the CPUidle driver, so that ARM legacy code can
> >> > cope with platform specific idle entry method based on compatible
> >> > string matching and the code used to initialize the enter function pointer
> >> > can be moved to the DT generic layer.
> >> >
> >> > Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> >> > Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
> >> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> >>
> >> [...]
> >>
> >> > + idle_state->flags = CPUIDLE_FLAG_TIME_VALID;
> >> > + if (of_property_read_bool(state_node, "local-timer-stop"))
> >> > + idle_state->flags |= CPUIDLE_FLAG_TIMER_STOP;
> >> > + /*
> >> > + * TODO:
> >> > + * replace with kstrdup and pointer assignment when name
> >> > + * and desc become string pointers
> >> > + */
> >> > + strncpy(idle_state->name, state_node->name, CPUIDLE_NAME_LEN - 1);
> >> > + strncpy(idle_state->desc, state_node->name, CPUIDLE_DESC_LEN - 1);
> >>
> >> This is a very minor concern, and shouldn't hold back this series,
> >> but...
> >>
> >> I was playing with this series in order to test out the qcom cpuidle
> >> driver from Lina, and noticed that the state name and descriptions were
> >> not terribly helpful:
> >>
> >> /sys/devices/system/cpu/cpu0/cpuidle # cat state?/name
> >> cpu-idle-state-
> >> cpu-idle-state-
> >> /sys/devices/system/cpu/cpu0/cpuidle # cat state?/desc
> >> cpu-idle-state-0
> >> cpu-idle-state-1
> >>
> >> Turns out these strings come from the node name itself, and truncated in
> >> the case of state->name, but this can be fixed in the DTS itself (c.f.
> >> reply to Lina's driver.)
> >>
> >> However, seeing that the node name is used to populate both the
> >> state->name and ->, made me wonder if there should better way to set the
> >> state->desc field to a more useful string. Tools like powertop actually
> >> use that field and it can be quite useful.
> >
> > Well, the truncation problem will be solved when those strings will be
> > kdup'ed, so for the name I think there is not a problem, copying the
> > state node is fine waiting for those strings to become pointers.
> >
> > For desc, there are four options:
> >
> > (1) enumerating idle states (but that's worse than copying the name into
> > desc since on ARM idle-state{1,2,3...} means nothing)
> > (2) copying the idle state node compatible string into desc
> > (3) Add an optional property to the DT bindings to describe the state
> > (4) Leave code as it is
> >
> > (3) I am not extremely keen at this stage to re-patch the DT bindings,
> > it has been an awful lot of work to make everyone agree so I would avoid
> > any changes, I hope you understand (and I am not even sure DT maintainers
> > would accept that, so even less keen on changing the DT bindings at this
> > stage).
> >
> > (2) I am not sure it will clarify the description much.
> >
> > (1) I would rule it out. So either we accept that the name can be
> > extended in length (that's going to be the case since we will
> > dynamically allocate the string so there will be no truncation, to
> > a reasonable extent) so (4) is fine, or we merge this code and I
> > will take care of pushing for (3) in a separate patch and copy the resulting
> > description into desc (if that change does not get NACK'ed).
> >
> > I would really want to see this code in the mailine asap since it is
> > groundwork for all future CPUidle generalisation, I hope that what I am
> > saying above is acceptable, please let me know what you think.
>
> Agreed, as I stated when I rasied this issue, it's a very minor concern
> and I don't think it should hold back this series.
>
> After this series is merged, I think approach (3) is probably the best
> and should be done as a follow-up patch/series.
I agree and that's what I will do, thank you Kevin (and Mark).
Lorenzo
^ permalink raw reply [flat|nested] 29+ messages in thread
end of thread, other threads:[~2014-09-09 15:51 UTC | newest]
Thread overview: 29+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2014-09-05 17:34 [PATCH v9 0/8] ARM generic idle states Lorenzo Pieralisi
2014-09-05 17:34 ` Lorenzo Pieralisi
2014-09-05 17:34 ` [PATCH v9 1/8] Documentation: arm: define DT idle states bindings Lorenzo Pieralisi
2014-09-05 17:34 ` Lorenzo Pieralisi
2014-09-05 17:34 ` [PATCH v9 2/8] arm64: kernel: refactor the CPU suspend API for retention states Lorenzo Pieralisi
2014-09-05 17:34 ` Lorenzo Pieralisi
2014-09-05 17:34 ` [PATCH v9 3/8] arm64: kernel: introduce cpu_init_idle CPU operation Lorenzo Pieralisi
2014-09-05 17:34 ` Lorenzo Pieralisi
2014-09-05 17:34 ` [PATCH v9 4/8] arm64: add PSCI CPU_SUSPEND based cpu_suspend support Lorenzo Pieralisi
2014-09-05 17:34 ` Lorenzo Pieralisi
2014-09-05 17:34 ` [PATCH v9 5/8] drivers: cpuidle: implement DT based idle states infrastructure Lorenzo Pieralisi
2014-09-05 17:34 ` Lorenzo Pieralisi
2014-09-05 20:00 ` Kevin Hilman
2014-09-05 21:29 ` Lorenzo Pieralisi
2014-09-05 21:29 ` Lorenzo Pieralisi
2014-09-05 21:36 ` Mark Brown
2014-09-05 21:36 ` Mark Brown
2014-09-08 15:58 ` Kevin Hilman
2014-09-08 15:58 ` Kevin Hilman
2014-09-09 15:51 ` Lorenzo Pieralisi
2014-09-09 15:51 ` Lorenzo Pieralisi
[not found] ` <1409938498-17984-1-git-send-email-lorenzo.pieralisi-5wv7dgnIgG8@public.gmane.org>
2014-09-05 17:34 ` [PATCH v9 6/8] drivers: cpuidle: CPU idle ARM64 driver Lorenzo Pieralisi
2014-09-05 17:34 ` Lorenzo Pieralisi
2014-09-08 16:08 ` Catalin Marinas
2014-09-08 16:08 ` Catalin Marinas
2014-09-05 17:34 ` [PATCH v9 7/8] drivers: cpuidle: initialize big.LITTLE driver through DT Lorenzo Pieralisi
2014-09-05 17:34 ` Lorenzo Pieralisi
2014-09-05 17:34 ` [PATCH v9 8/8] drivers: cpuidle: initialize Exynos " Lorenzo Pieralisi
2014-09-05 17:34 ` Lorenzo Pieralisi
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