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cpu_pm: Add cpu power management notifiers

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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.

Notified drivers can include VFP co-processor, interrupt controller
and it's PM extensions, local CPU timers context save/restore which
shouldn't be interrupted. Hence CPU PM event APIs  must be called
with interrupts disabled.

Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Tested-and-Acked-by: Shawn Guo <shawn.guo@linaro.org>
Tested-by: Kevin Hilman <khilman@ti.com>
Tested-by: Vishwanath BS <vishwanath.bs@ti.com>
This commit is contained in:
Colin Cross 2011-02-10 02:04:45 -08:00 committed by Santosh Shilimkar
parent b6fd41e29d
commit ab10023e00
4 changed files with 314 additions and 0 deletions
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109
include/linux/cpu_pm.h Normal file
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@ -0,0 +1,109 @@
/*
* Copyright (C) 2011 Google, Inc.
*
* Author:
* Colin Cross <ccross@android.com>
*
* 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 _LINUX_CPU_PM_H
#define _LINUX_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,
* interrupt 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
* cluster 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 cluster 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_CLUSTER_PM_ENTER,
/* A cpu power domain failed to enter a low power state */
CPU_CLUSTER_PM_ENTER_FAILED,
/* A cpu power domain is exiting a low power state */
CPU_CLUSTER_PM_EXIT,
};
#ifdef CONFIG_CPU_PM
int cpu_pm_register_notifier(struct notifier_block *nb);
int cpu_pm_unregister_notifier(struct notifier_block *nb);
int cpu_pm_enter(void);
int cpu_pm_exit(void);
int cpu_cluster_pm_enter(void);
int cpu_cluster_pm_exit(void);
#else
static inline int cpu_pm_register_notifier(struct notifier_block *nb)
{
return 0;
}
static inline int cpu_pm_unregister_notifier(struct notifier_block *nb)
{
return 0;
}
static inline int cpu_pm_enter(void)
{
return 0;
}
static inline int cpu_pm_exit(void)
{
return 0;
}
static inline int cpu_cluster_pm_enter(void)
{
return 0;
}
static inline int cpu_cluster_pm_exit(void)
{
return 0;
}
#endif
#endif

1
kernel/Makefile
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@ -101,6 +101,7 @@ obj-$(CONFIG_RING_BUFFER) += trace/
obj-$(CONFIG_TRACEPOINTS) += trace/
obj-$(CONFIG_SMP) += sched_cpupri.o
obj-$(CONFIG_IRQ_WORK) += irq_work.o
obj-$(CONFIG_CPU_PM) += cpu_pm.o
obj-$(CONFIG_PERF_EVENTS) += events/

200
kernel/cpu_pm.c Normal file
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@ -0,0 +1,200 @@
/*
* Copyright (C) 2011 Google, Inc.
*
* Author:
* Colin Cross <ccross@android.com>
*
* 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/cpu_pm.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/spinlock.h>
static DEFINE_RWLOCK(cpu_pm_notifier_lock);
static RAW_NOTIFIER_HEAD(cpu_pm_notifier_chain);
static int cpu_pm_notify(enum cpu_pm_event event, int nr_to_call, int *nr_calls)
{
int ret;
ret = __raw_notifier_call_chain(&cpu_pm_notifier_chain, event, NULL,
nr_to_call, nr_calls);
return notifier_to_errno(ret);
}
/**
* cpu_pm_register_notifier - register a driver with cpu_pm
* @nb: notifier block to register
*
* Add a driver to a list of drivers that are notified about
* CPU and CPU cluster low power entry and exit.
*
* This function may sleep, and has the same return conditions as
* raw_notifier_chain_register.
*/
int cpu_pm_register_notifier(struct notifier_block *nb)
{
unsigned long flags;
int ret;
write_lock_irqsave(&cpu_pm_notifier_lock, flags);
ret = raw_notifier_chain_register(&cpu_pm_notifier_chain, nb);
write_unlock_irqrestore(&cpu_pm_notifier_lock, flags);
return ret;
}
EXPORT_SYMBOL_GPL(cpu_pm_register_notifier);
/**
* cpu_pm_unregister_notifier - unregister a driver with cpu_pm
* @nb: notifier block to be unregistered
*
* Remove a driver from the CPU PM notifier list.
*
* This function may sleep, and has the same return conditions as
* raw_notifier_chain_unregister.
*/
int cpu_pm_unregister_notifier(struct notifier_block *nb)
{
unsigned long flags;
int ret;
write_lock_irqsave(&cpu_pm_notifier_lock, flags);
ret = raw_notifier_chain_unregister(&cpu_pm_notifier_chain, nb);
write_unlock_irqrestore(&cpu_pm_notifier_lock, flags);
return ret;
}
EXPORT_SYMBOL_GPL(cpu_pm_unregister_notifier);
/**
* cpm_pm_enter - CPU low power entry notifier
*
* 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. Notified drivers can include VFP
* co-processor, interrupt controller and it's PM extensions, local CPU
* timers context save/restore which shouldn't be interrupted. Hence it
* must be called with interrupts disabled.
*
* Return conditions are same as __raw_notifier_call_chain.
*/
int cpu_pm_enter(void)
{
int nr_calls;
int ret = 0;
read_lock(&cpu_pm_notifier_lock);
ret = cpu_pm_notify(CPU_PM_ENTER, -1, &nr_calls);
if (ret)
/*
* Inform listeners (nr_calls - 1) about failure of CPU PM
* PM entry who are notified earlier to prepare for it.
*/
cpu_pm_notify(CPU_PM_ENTER_FAILED, nr_calls - 1, NULL);
read_unlock(&cpu_pm_notifier_lock);
return ret;
}
EXPORT_SYMBOL_GPL(cpu_pm_enter);
/**
* cpm_pm_exit - CPU low power exit notifier
*
* 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.
*
* Notified drivers can include VFP co-processor, interrupt controller
* and it's PM extensions, local CPU timers context save/restore which
* shouldn't be interrupted. Hence it must be called with interrupts disabled.
*
* Return conditions are same as __raw_notifier_call_chain.
*/
int cpu_pm_exit(void)
{
int ret;
read_lock(&cpu_pm_notifier_lock);
ret = cpu_pm_notify(CPU_PM_EXIT, -1, NULL);
read_unlock(&cpu_pm_notifier_lock);
return ret;
}
EXPORT_SYMBOL_GPL(cpu_pm_exit);
/**
* cpm_cluster_pm_enter - CPU cluster low power entry notifier
*
* 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. Notified drivers can include VFP co-processor, interrupt controller
* and it's PM extensions, local CPU timers context save/restore which
* shouldn't be interrupted. Hence it must be called with interrupts disabled.
*
* Must be called with interrupts disabled.
*
* Return conditions are same as __raw_notifier_call_chain.
*/
int cpu_cluster_pm_enter(void)
{
int nr_calls;
int ret = 0;
read_lock(&cpu_pm_notifier_lock);
ret = cpu_pm_notify(CPU_CLUSTER_PM_ENTER, -1, &nr_calls);
if (ret)
/*
* Inform listeners (nr_calls - 1) about failure of CPU cluster
* PM entry who are notified earlier to prepare for it.
*/
cpu_pm_notify(CPU_CLUSTER_PM_ENTER_FAILED, nr_calls - 1, NULL);
read_unlock(&cpu_pm_notifier_lock);
return ret;
}
EXPORT_SYMBOL_GPL(cpu_cluster_pm_enter);
/**
* cpm_cluster_pm_exit - CPU cluster low power exit notifier
*
* Notifies listeners that all cpus in a power domain are exiting form a
* low power state that may have caused some blocks in the same power domain
* to reset.
*
* Must be called after cpu_pm_exit 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. Notified drivers can include VFP co-processor, interrupt controller
* and it's PM extensions, local CPU timers context save/restore which
* shouldn't be interrupted. Hence it must be called with interrupts disabled.
*
* Return conditions are same as __raw_notifier_call_chain.
*/
int cpu_cluster_pm_exit(void)
{
int ret;
read_lock(&cpu_pm_notifier_lock);
ret = cpu_pm_notify(CPU_CLUSTER_PM_EXIT, -1, NULL);
read_unlock(&cpu_pm_notifier_lock);
return ret;
}
EXPORT_SYMBOL_GPL(cpu_cluster_pm_exit);

4
kernel/power/Kconfig
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@ -235,3 +235,7 @@ config PM_GENERIC_DOMAINS
config PM_GENERIC_DOMAINS_RUNTIME
def_bool y
depends on PM_RUNTIME && PM_GENERIC_DOMAINS
config CPU_PM
bool
depends on SUSPEND || CPU_IDLE