From: lakshmi.sowjanya.d@intel.com
To: tglx@linutronix.de, jstultz@google.com, giometti@enneenne.com,
corbet@lwn.net, linux-kernel@vger.kernel.org
Cc: x86@kernel.org, netdev@vger.kernel.org,
linux-doc@vger.kernel.org, intel-wired-lan@lists.osuosl.org,
andriy.shevchenko@linux.intel.com, eddie.dong@intel.com,
christopher.s.hall@intel.com, jesse.brandeburg@intel.com,
davem@davemloft.net, alexandre.torgue@foss.st.com,
joabreu@synopsys.com, mcoquelin.stm32@gmail.com, perex@perex.cz,
linux-sound@vger.kernel.org, anthony.l.nguyen@intel.com,
peter.hilber@opensynergy.com, pandith.n@intel.com,
subramanian.mohan@intel.com, thejesh.reddy.t.r@intel.com,
lakshmi.sowjanya.d@intel.com
Subject: [PATCH v7 00/12] Add support for Intel PPS Generator
Date: Tue, 30 Apr 2024 14:22:13 +0530 [thread overview]
Message-ID: <20240430085225.18086-1-lakshmi.sowjanya.d@intel.com> (raw)
From: Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com>
The goal of the PPS (Pulse Per Second) hardware/software is to generate a
signal from the system on a wire so that some third-party hardware can
observe that signal and judge how close the system's time is to another
system or piece of hardware.
Existing methods (like parallel ports) require software to flip a bit at
just the right time to create a PPS signal. Many things can prevent
software from doing this precisely. This (Timed I/O) method is better
because software only "arms" the hardware in advance and then depends on
the hardware to "fire" and flip the signal at just the right time.
To generate a PPS signal with this new hardware, the kernel wakes up
twice a second, once for 1->0 edge and other for the 0->1 edge. It does
this shortly (~10ms) before the actual change in the signal needs to be
made. It computes the TSC value at which edge will happen, convert to a
value hardware understands and program this value to Timed I/O hardware.
The actual edge transition happens without any further action from the
kernel.
The result here is a signal coming out of the system that is roughly
1,000 times more accurate than the old methods. If the system is heavily
loaded, the difference in accuracy is larger in old methods.
Application Interface:
The API to use Timed I/O is very simple. It is enabled and disabled by
writing a '1' or '0' value to the sysfs enable attribute associated with
the Timed I/O PPS device. Each Timed I/O pin is represented by a PPS
device. When enabled, a pulse-per-second (PPS) synchronized with the
system clock is continuously produced on the Timed I/O pin, otherwise it
is pulled low.
The Timed I/O signal on the motherboard is enabled in the BIOS setup.
Intel Advanced Menu -> PCH IO Configuration -> Timed I/O <Enable>
References:
https://en.wikipedia.org/wiki/Pulse-per-second_signal
https://drive.google.com/file/d/1vkBRRDuELmY8I3FlfOZaEBp-DxLW6t_V/view
https://youtu.be/JLUTT-lrDqw
Patch 1 adds base clock properties in clocksource structure
Patch 2 updates tsc, art values in the base clock structure
Patch 3 - 7 removes reference to convert_art_to_tsc function across
drivers
Patch 8 removes the convert art to tsc functions which are no longer
used
Patch 9 adds function to convert realtime to base clock
Patch 10 adds the pps(pulse per second) generator tio driver to the pps
subsystem.
Patch 11 documentation and usage of the pps tio generator module.
Patch 12 includes documentation for sysfs interface.
Please help to review the changes.
Thanks in advance,
Sowjanya
Changes from v2:
- Split patch 1 to remove the functions in later stages.
- Include required headers in pps_gen_tio.
Changes from v3:
- Corrections in Documentation.
- Introducing non-RFC version of the patch series.
Changes from v4:
- Setting id in ice_ptp
- Modified conversion logic in convert_base_to_cs.
- Included the usage of the APIs in the commit message of 2nd patch.
Changes from v5:
- Change nsecs variable to use_nsecs.
- Change order of 1&2 patches and modify the commit message.
- Add sysfs abi file entry in MAINTAINERS file.
- Add check to find if any event is missed and disable hardware
accordingly.
Changes from v6:
- Split patch 1 into 1&2 patches.
- Add check for overflow in convert_ns_to_cs().
- Refine commit messages.
Lakshmi Sowjanya D (7):
timekeeping: Add base clock properties in clocksource structure
x86/tsc: Update tsc/art values in the base clock structure
x86/tsc: Remove art to tsc conversion functions which are obsolete
timekeeping: Add function to convert realtime to base clock
pps: generators: Add PPS Generator TIO Driver
Documentation: driver-api: pps: Add Intel Timed I/O PPS generator
ABI: pps: Add ABI documentation for Intel TIO
Thomas Gleixner (5):
e1000e: remove convert_art_to_tsc()
igc: remove convert_art_ns_to_tsc()
stmmac: intel: remove convert_art_to_tsc()
ALSA: hda: remove convert_art_to_tsc()
ice/ptp: remove convert_art_to_tsc()
.../ABI/testing/sysfs-platform-pps-tio | 7 +
Documentation/driver-api/pps.rst | 22 ++
MAINTAINERS | 1 +
arch/x86/include/asm/tsc.h | 3 -
arch/x86/kernel/tsc.c | 92 ++-----
drivers/net/ethernet/intel/e1000e/ptp.c | 3 +-
drivers/net/ethernet/intel/ice/ice_ptp.c | 3 +-
drivers/net/ethernet/intel/igc/igc_ptp.c | 6 +-
.../net/ethernet/stmicro/stmmac/dwmac-intel.c | 3 +-
drivers/pps/generators/Kconfig | 16 ++
drivers/pps/generators/Makefile | 1 +
drivers/pps/generators/pps_gen_tio.c | 260 ++++++++++++++++++
include/linux/clocksource.h | 27 ++
include/linux/clocksource_ids.h | 1 +
include/linux/timekeeping.h | 6 +
kernel/time/timekeeping.c | 125 ++++++++-
sound/pci/hda/hda_controller.c | 3 +-
17 files changed, 496 insertions(+), 83 deletions(-)
create mode 100644 Documentation/ABI/testing/sysfs-platform-pps-tio
create mode 100644 drivers/pps/generators/pps_gen_tio.c
--
2.35.3
next reply other threads:[~2024-04-30 8:52 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-30 8:52 lakshmi.sowjanya.d [this message]
2024-04-30 8:52 ` [PATCH v7 01/12] timekeeping: Add base clock properties in clocksource structure lakshmi.sowjanya.d
2024-04-30 14:28 ` Peter Hilber
2024-05-09 4:38 ` D, Lakshmi Sowjanya
2024-04-30 8:52 ` [PATCH v7 02/12] x86/tsc: Update tsc/art values in the base clock structure lakshmi.sowjanya.d
2024-04-30 8:52 ` [PATCH v7 03/12] e1000e: remove convert_art_to_tsc() lakshmi.sowjanya.d
2024-04-30 8:52 ` [PATCH v7 04/12] igc: remove convert_art_ns_to_tsc() lakshmi.sowjanya.d
2024-04-30 8:52 ` [PATCH v7 05/12] stmmac: intel: remove convert_art_to_tsc() lakshmi.sowjanya.d
2024-04-30 8:52 ` [PATCH v7 06/12] ALSA: hda: " lakshmi.sowjanya.d
2024-04-30 8:52 ` [PATCH v7 07/12] ice/ptp: " lakshmi.sowjanya.d
2024-04-30 8:52 ` [PATCH v7 08/12] x86/tsc: Remove art to tsc conversion functions which are obsolete lakshmi.sowjanya.d
2024-04-30 8:52 ` [PATCH v7 09/12] timekeeping: Add function to convert realtime to base clock lakshmi.sowjanya.d
2024-04-30 16:27 ` [Intel-wired-lan] " kernel test robot
2024-04-30 8:52 ` [PATCH v7 10/12] pps: generators: Add PPS Generator TIO Driver lakshmi.sowjanya.d
2024-04-30 13:53 ` Andy Shevchenko
2024-05-09 4:38 ` D, Lakshmi Sowjanya
2024-05-10 14:27 ` Andy Shevchenko
2024-04-30 8:52 ` [PATCH v7 11/12] Documentation: driver-api: pps: Add Intel Timed I/O PPS generator lakshmi.sowjanya.d
2024-04-30 8:52 ` [PATCH v7 12/12] ABI: pps: Add ABI documentation for Intel TIO lakshmi.sowjanya.d
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