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/*
* 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>
#include <linux/syscore_ops.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);

#ifdef CONFIG_PM
static int cpu_pm_suspend(void)
{
int ret;

ret = cpu_pm_enter();
if (ret)
return ret;

ret = cpu_cluster_pm_enter();
return ret;
}

static void cpu_pm_resume(void)
{
cpu_cluster_pm_exit();
cpu_pm_exit();
}

static struct syscore_ops cpu_pm_syscore_ops = {
.suspend = cpu_pm_suspend,
.resume = cpu_pm_resume,
};

static int cpu_pm_init(void)
{
register_syscore_ops(&cpu_pm_syscore_ops);
return 0;
}
core_initcall(cpu_pm_init);
#endif
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