215 lines
6.1 KiB
C
215 lines
6.1 KiB
C
// 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
|