During some CPU power modes entered during idle, hotplug and
suspend, peripherals located in the CPU power domain, such as
the GIC, localtimers, and VFP, may be powered down. Add a
notifier chain that allows drivers for those peripherals to
be notified before and after they may be reset.
Signed-off-by: Colin Cross <[email protected]>
---
arch/arm/include/asm/cpu_pm.h | 123 +++++++++++++++++++++++++++++++++++++++++
arch/arm/kernel/Makefile | 1 +
arch/arm/kernel/cpu_pm.c | 116 ++++++++++++++++++++++++++++++++++++++
3 files changed, 240 insertions(+), 0 deletions(-)
create mode 100644 arch/arm/include/asm/cpu_pm.h
create mode 100644 arch/arm/kernel/cpu_pm.c
diff --git a/arch/arm/include/asm/cpu_pm.h b/arch/arm/include/asm/cpu_pm.h
new file mode 100644
index 0000000..07b1b6e
--- /dev/null
+++ b/arch/arm/include/asm/cpu_pm.h
@@ -0,0 +1,123 @@
+/*
+ * Copyright (C) 2011 Google, Inc.
+ *
+ * Author:
+ * Colin Cross <[email protected]>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef _ASMARM_CPU_PM_H
+#define _ASMARM_CPU_PM_H
+
+#include <linux/kernel.h>
+#include <linux/notifier.h>
+
+/*
+ * When a CPU goes to a low power state that turns off power to the CPU's
+ * power domain, the contents of some blocks (floating point coprocessors,
+ * interrutp controllers, caches, timers) in the same power domain can
+ * be lost. The cpm_pm notifiers provide a method for platform idle, suspend,
+ * and hotplug implementations to notify the drivers for these blocks that
+ * they may be reset.
+ *
+ * All cpu_pm notifications must be called with interrupts disabled.
+ *
+ * The notifications are split into two classes, CPU notifications and CPU
+ * complex notifications.
+ *
+ * CPU notifications apply to a single CPU, and must be called on the affected
+ * CPU. They are used to save per-cpu context for affected blocks.
+ *
+ * CPU complex notifications apply to all CPUs in a single power domain. They
+ * are used to save any global context for affected blocks, and must be called
+ * after all the CPUs in the power domain have been notified of the low power
+ * state.
+ *
+ */
+
+/*
+ * Event codes passed as unsigned long val to notifier calls
+ */
+enum cpu_pm_event {
+ /* A single cpu is entering a low power state */
+ CPU_PM_ENTER,
+
+ /* A single cpu failed to enter a low power state */
+ CPU_PM_ENTER_FAILED,
+
+ /* A single cpu is exiting a low power state */
+ CPU_PM_EXIT,
+
+ /* A cpu power domain is entering a low power state */
+ CPU_COMPLEX_PM_ENTER,
+
+ /* A cpu power domain failed to enter a low power state */
+ CPU_COMPLEX_PM_ENTER_FAILED,
+
+ /* A cpu power domain is exiting a low power state */
+ CPU_COMPLEX_PM_EXIT,
+};
+
+int cpu_pm_register_notifier(struct notifier_block *nb);
+int cpu_pm_unregister_notifier(struct notifier_block *nb);
+
+/*
+ * cpm_pm_enter
+ *
+ * Notifies listeners that a single cpu is entering a low power state that may
+ * cause some blocks in the same power domain as the cpu to reset.
+ *
+ * Must be called on the affected cpu with interrupts disabled. Platform is
+ * responsible for ensuring that cpu_pm_enter is not called twice on the same
+ * cpu before cpu_pm_exit is called.
+ */
+int cpu_pm_enter(void);
+
+/*
+ * cpm_pm_exit
+ *
+ * Notifies listeners that a single cpu is exiting a low power state that may
+ * have caused some blocks in the same power domain as the cpu to reset.
+ *
+ * Must be called on the affected cpu with interrupts disabled.
+ */
+int cpu_pm_exit(void);
+
+/*
+ * cpm_complex_pm_enter
+ *
+ * Notifies listeners that all cpus in a power domain are entering a low power
+ * state that may cause some blocks in the same power domain to reset.
+ *
+ * Must be called after cpu_pm_enter has been called on all cpus in the power
+ * domain, and before cpu_pm_exit has been called on any cpu in the power
+ * domain.
+ *
+ * Must be called with interrupts disabled.
+ */
+int cpu_complex_pm_enter(void);
+
+/*
+ * cpm_pm_enter
+ *
+ * Notifies listeners that a single cpu is entering a low power state that may
+ * cause some blocks in the same power domain as the cpu to reset.
+ *
+ * Must be called after cpu_pm_enter has been called on all cpus in the power
+ * domain, and before cpu_pm_exit has been called on any cpu in the power
+ * domain.
+ *
+ * Must be called with interrupts disabled.
+ */
+int cpu_complex_pm_exit(void);
+
+#endif
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 185ee82..b0f25cb 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -58,6 +58,7 @@ obj-$(CONFIG_CPU_PJ4) += pj4-cp0.o
obj-$(CONFIG_IWMMXT) += iwmmxt.o
obj-$(CONFIG_CPU_HAS_PMU) += pmu.o
obj-$(CONFIG_HW_PERF_EVENTS) += perf_event.o
+obj-$(CONFIG_CPU_IDLE) += cpu_pm.o
AFLAGS_iwmmxt.o := -Wa,-mcpu=iwmmxt
ifneq ($(CONFIG_ARCH_EBSA110),y)
diff --git a/arch/arm/kernel/cpu_pm.c b/arch/arm/kernel/cpu_pm.c
new file mode 100644
index 0000000..9a04ba1
--- /dev/null
+++ b/arch/arm/kernel/cpu_pm.c
@@ -0,0 +1,116 @@
+/*
+ * Copyright (C) 2011 Google, Inc.
+ *
+ * Author:
+ * Colin Cross <[email protected]>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/notifier.h>
+#include <linux/smp.h>
+
+#include <asm/cpu_pm.h>
+
+static DEFINE_SPINLOCK(idle_notifier_lock);
+static RAW_NOTIFIER_HEAD(idle_notifier_chain);
+
+int cpu_pm_register_notifier(struct notifier_block *nb)
+{
+ unsigned long flags;
+ int ret;
+
+ spin_lock_irqsave(&idle_notifier_lock, flags);
+ ret = raw_notifier_chain_register(&idle_notifier_chain, nb);
+ spin_unlock_irqrestore(&idle_notifier_lock, flags);
+
+ return ret;
+}
+
+int cpu_pm_unregister_notifier(struct notifier_block *nb)
+{
+ unsigned long flags;
+ int ret;
+
+ spin_lock_irqsave(&idle_notifier_lock, flags);
+ ret = raw_notifier_chain_unregister(&idle_notifier_chain, nb);
+ spin_unlock_irqrestore(&idle_notifier_lock, flags);
+
+ return ret;
+}
+
+static int __idle_notify(enum cpu_pm_event event, int nr_to_call,
+ int *nr_calls)
+{
+ int ret;
+
+ ret = __raw_notifier_call_chain(&idle_notifier_chain, event, NULL,
+ nr_to_call, nr_calls);
+
+ return notifier_to_errno(ret);
+}
+
+int cpu_pm_enter(void)
+{
+ int nr_calls;
+ int ret;
+
+ spin_lock(&idle_notifier_lock);
+ ret = __idle_notify(CPU_PM_ENTER, -1, &nr_calls);
+ if (ret) {
+ __idle_notify(CPU_PM_ENTER_FAILED, nr_calls - 1, NULL);
+ spin_unlock(&idle_notifier_lock);
+ return ret;
+ }
+ spin_unlock(&idle_notifier_lock);
+
+ return 0;
+}
+
+int cpu_pm_exit(void)
+{
+ int ret;
+
+ spin_lock(&idle_notifier_lock);
+ ret = __idle_notify(CPU_PM_EXIT, -1, NULL);
+ spin_unlock(&idle_notifier_lock);
+
+ return ret;
+}
+
+int cpu_complex_pm_enter(void)
+{
+ int nr_calls;
+ int ret;
+
+ spin_lock(&idle_notifier_lock);
+ ret = __idle_notify(CPU_COMPLEX_PM_ENTER, -1, &nr_calls);
+ if (ret) {
+ __idle_notify(CPU_COMPLEX_PM_ENTER_FAILED, nr_calls - 1, NULL);
+ spin_unlock(&idle_notifier_lock);
+ return ret;
+ }
+ spin_unlock(&idle_notifier_lock);
+
+ return 0;
+}
+
+int cpu_complex_pm_exit(void)
+{
+ int ret;
+
+ spin_lock(&idle_notifier_lock);
+ ret = __idle_notify(CPU_COMPLEX_PM_EXIT, -1, NULL);
+ spin_unlock(&idle_notifier_lock);
+
+ return ret;
+}
--
1.7.3.1
On Thu, Feb 10, 2011 at 01:31:25PM -0800, Colin Cross wrote:
> +int cpu_pm_enter(void)
> +{
> + int nr_calls;
> + int ret;
> +
> + spin_lock(&idle_notifier_lock);
> + ret = __idle_notify(CPU_PM_ENTER, -1, &nr_calls);
> + if (ret) {
> + __idle_notify(CPU_PM_ENTER_FAILED, nr_calls - 1, NULL);
> + spin_unlock(&idle_notifier_lock);
> + return ret;
> + }
> + spin_unlock(&idle_notifier_lock);
> +
> + return 0;
Wouldn't:
spin_lock(&idle_notifier_lock);
ret = __idle_notify(CPU_PM_ENTER, -1, &nr_calls);
if (ret)
__idle_notify(CPU_PM_ENTER_FAILED, nr_calls - 1, NULL);
spin_unlock(&idle_notifier_lock);
return ret;
be easier reading?