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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2011 Google, Inc.
*
* Author:
* Colin Cross <ccross@android.com>
*/
#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>
/*
* atomic_notifiers use a spinlock_t, which can block under PREEMPT_RT.
* Notifications for cpu_pm will be issued by the idle task itself, which can
* never block, IOW it requires using a raw_spinlock_t.
*/
static struct {
struct raw_notifier_head chain;
raw_spinlock_t lock;
} cpu_pm_notifier = {
.chain = RAW_NOTIFIER_INIT(cpu_pm_notifier.chain),
.lock = __RAW_SPIN_LOCK_UNLOCKED(cpu_pm_notifier.lock),
};
static int cpu_pm_notify(enum cpu_pm_event event)
{
int ret;
/*
* This introduces a RCU read critical section, which could be
* disfunctional in cpu idle. Copy RCU_NONIDLE code to let RCU know
* this.
*/
rcu_irq_enter_irqson();
rcu_read_lock();
ret = raw_notifier_call_chain(&cpu_pm_notifier.chain, event, NULL);
rcu_read_unlock();
rcu_irq_exit_irqson();
return notifier_to_errno(ret);
}
static int cpu_pm_notify_robust(enum cpu_pm_event event_up, enum cpu_pm_event event_down)
{
unsigned long flags;
int ret;
rcu_irq_enter_irqson();
raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
ret = raw_notifier_call_chain_robust(&cpu_pm_notifier.chain, event_up, event_down, NULL);
raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
rcu_irq_exit_irqson();
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 has the same return conditions as raw_notifier_chain_register.
*/
int cpu_pm_register_notifier(struct notifier_block *nb)
{
unsigned long flags;
int ret;
raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
ret = raw_notifier_chain_register(&cpu_pm_notifier.chain, nb);
raw_spin_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 has the same return conditions as raw_notifier_chain_unregister.
*/
int cpu_pm_unregister_notifier(struct notifier_block *nb)
{
unsigned long flags;
int ret;
raw_spin_lock_irqsave(&cpu_pm_notifier.lock, flags);
ret = raw_notifier_chain_unregister(&cpu_pm_notifier.chain, nb);
raw_spin_unlock_irqrestore(&cpu_pm_notifier.lock, flags);
return ret;
}
EXPORT_SYMBOL_GPL(cpu_pm_unregister_notifier);
/**
* cpu_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 its 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)
{
return cpu_pm_notify_robust(CPU_PM_ENTER, CPU_PM_ENTER_FAILED);
}
EXPORT_SYMBOL_GPL(cpu_pm_enter);
/**
* cpu_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 its 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)
{
return cpu_pm_notify(CPU_PM_EXIT);
}
EXPORT_SYMBOL_GPL(cpu_pm_exit);
/**
* cpu_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 its 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)
{
return cpu_pm_notify_robust(CPU_CLUSTER_PM_ENTER, CPU_CLUSTER_PM_ENTER_FAILED);
}
EXPORT_SYMBOL_GPL(cpu_cluster_pm_enter);
/**
* cpu_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_cluster_pm_enter has been called for 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 its 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)
{
return cpu_pm_notify(CPU_CLUSTER_PM_EXIT);
}
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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