cpu_pm.c

/*
 * 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)
{