// 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; 	rcu_read_lock();	ret = raw_notifier_call_chain(&cpu_pm_notifier.chain, event, NULL);	rcu_read_unlock(); 	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; 	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); 	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_PMstatic 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