From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lorenzo Pieralisi Subject: Re: [PATCH v8 4/8] arm64: kernel: introduce cpu_init_idle CPU operation Date: Wed, 3 Sep 2014 18:46:45 +0100 Message-ID: <20140903174645.GK1824@e102568-lin.cambridge.arm.com> References: <1409585324-3678-1-git-send-email-lorenzo.pieralisi@arm.com> <1409585324-3678-5-git-send-email-lorenzo.pieralisi@arm.com> <20140903173437.GI92149@ilina-mac.local> Mime-Version: 1.0 Content-Type: text/plain; charset=WINDOWS-1252 Content-Transfer-Encoding: 8BIT Return-path: In-Reply-To: <20140903173437.GI92149@ilina-mac.local> Content-Disposition: inline Sender: linux-pm-owner@vger.kernel.org To: Lina Iyer Cc: "linux-arm-kernel@lists.infradead.org" , "linux-pm@vger.kernel.org" , "devicetree@vger.kernel.org" , Mark Rutland , Sudeep Holla , Catalin Marinas , 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 , Kevin Hilman , Sebastian Capella , Tomasz Figa List-Id: devicetree@vger.kernel.org On Wed, Sep 03, 2014 at 06:34:37PM +0100, Lina Iyer wrote: > On Mon, Sep 01 2014 at 09:28 -0600, Lorenzo Pieralisi wrote: > >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. > > > I like the change for ARM64. > However, that raises a question, how do I have the same driver that > should get probed by a platform device (on 32 bit ARM) and getting called > from cpu_init_idle on ARM64? I am not following you sorry. The ARM64 CPUidle driver calls the arm64 cpu_init_idle hooks to initialize idle states (in a generic way from a driver perspective), not the other way around. On ARM64 your idle driver rely on an arm64 suspend back-end (eg PSCI) to enter idle states, it works in a different way from ARM, on purpose. Have a look at what the code does, it won't be the same driver that's for certain, since on arm64 I do not want to cope with per-platform CPUidle state enter functions anymore, the arm64 cpu_ops suspend hook implements the idle state enter method. Lorenzo > >Reviewed-by: Catalin Marinas > >Signed-off-by: Lorenzo Pieralisi > >--- > > 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 > >+ * > >+ * 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 > >+#include > >+ > >+#include > >+#include > >+ > >+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 > > > > > -- > To unsubscribe from this list: send the line "unsubscribe devicetree" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > From mboxrd@z Thu Jan 1 00:00:00 1970 From: lorenzo.pieralisi@arm.com (Lorenzo Pieralisi) Date: Wed, 3 Sep 2014 18:46:45 +0100 Subject: [PATCH v8 4/8] arm64: kernel: introduce cpu_init_idle CPU operation In-Reply-To: <20140903173437.GI92149@ilina-mac.local> References: <1409585324-3678-1-git-send-email-lorenzo.pieralisi@arm.com> <1409585324-3678-5-git-send-email-lorenzo.pieralisi@arm.com> <20140903173437.GI92149@ilina-mac.local> Message-ID: <20140903174645.GK1824@e102568-lin.cambridge.arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Sep 03, 2014 at 06:34:37PM +0100, Lina Iyer wrote: > On Mon, Sep 01 2014 at 09:28 -0600, Lorenzo Pieralisi wrote: > >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. > > > I like the change for ARM64. > However, that raises a question, how do I have the same driver that > should get probed by a platform device (on 32 bit ARM) and getting called > from cpu_init_idle on ARM64? I am not following you sorry. The ARM64 CPUidle driver calls the arm64 cpu_init_idle hooks to initialize idle states (in a generic way from a driver perspective), not the other way around. On ARM64 your idle driver rely on an arm64 suspend back-end (eg PSCI) to enter idle states, it works in a different way from ARM, on purpose. Have a look at what the code does, it won't be the same driver that's for certain, since on arm64 I do not want to cope with per-platform CPUidle state enter functions anymore, the arm64 cpu_ops suspend hook implements the idle state enter method. Lorenzo > >Reviewed-by: Catalin Marinas > >Signed-off-by: Lorenzo Pieralisi > >--- > > 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 > >+ * > >+ * 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 > >+#include > >+ > >+#include > >+#include > >+ > >+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 > > > > > -- > To unsubscribe from this list: send the line "unsubscribe devicetree" in > the body of a message to majordomo at vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >