/* * 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 ATOMIC_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; /* * __atomic_notifier_call_chain has 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(); ret = __atomic_notifier_call_chain(&cpu_pm_notifier_chain, event, NULL, nr_to_call, nr_calls); 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 may sleep, and has the same return conditions as * raw_notifier_chain_register. */ int cpu_pm_register_notifier(struct notifier_block *nb) { return atomic_notifier_chain_register(&cpu_pm_notifier_chain, nb); } 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) { return atomic_notifier_chain_unregister(&cpu_pm_notifier_chain, nb); } 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) { int nr_calls; int ret = 0; 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); return ret; } 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, -1, NULL); } 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) { int nr_calls; int ret = 0; 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); return ret; } 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, -1, NULL); } 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