path: root/drivers/base/power/runtime.c

/*
 * drivers/base/power/runtime.c - Helper functions for device runtime PM
 *
 * Copyright (c) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
 * Copyright (C) 2010 Alan Stern <stern@rowland.harvard.edu>
 *
 * This file is released under the GPLv2.
 */

#include <linux/sched.h>
#include <linux/pm_runtime.h>
#include "power.h"

static int rpm_resume(struct device *dev, int rpmflags);
static int rpm_suspend(struct device *dev, int rpmflags);

/**
 * update_pm_runtime_accounting - Update the time accounting of power states
 * @dev: Device to update the accounting for
 *
 * In order to be able to have time accounting of the various power states
 * (as used by programs such as PowerTOP to show the effectiveness of runtime
 * PM), we need to track the time spent in each state.
 * update_pm_runtime_accounting must be called each time before the
 * runtime_status field is updated, to account the time in the old state
 * correctly.
 */
void update_pm_runtime_accounting(struct device *dev)
{
	unsigned long now = jiffies;
	int delta;

	delta = now - dev->power.accounting_timestamp;

	if (delta < 0)
		delta = 0;

	dev->power.accounting_timestamp = now;

	if (dev->power.disable_depth > 0)
		return;

	if (dev->power.runtime_status == RPM_SUSPENDED)
		dev->power.suspended_jiffies += delta;
	else
		dev->power.active_jiffies += delta;
}

static void __update_runtime_status(struct device *dev, enum rpm_status status)
{
	update_pm_runtime_accounting(dev);
	dev->power.runtime_status = status;
}

/**
 * pm_runtime_deactivate_timer - Deactivate given device's suspend timer.
 * @dev: Device to handle.
 */
static void pm_runtime_deactivate_timer(struct device *dev)
{
	if (dev->power.timer_expires > 0) {
		del_timer(&dev->power.suspend_timer);
		dev->power.timer_expires = 0;
	}
}

/**
 * pm_runtime_cancel_pending - Deactivate suspend timer and cancel requests.
 * @dev: Device to handle.
 */
static void pm_runtime_cancel_pending(struct device *dev)
{
	pm_runtime_deactivate_timer(dev);
	/*
	 * In case there's a request pending, make sure its work function will
	 * return without doing anything.
	 */
	dev->power.request = RPM_REQ_NONE;
}

/*
 * pm_runtime_autosuspend_expiration - Get a device's autosuspend-delay expiration time.
 * @dev: Device to handle.
 *
 * Compute the autosuspend-delay expiration time based on the device's
 * power.last_busy time.  If the delay has already expired or is disabled
 * (negative) or the power.use_autosuspend flag isn't set, return 0.
 * Otherwise return the expiration time in jiffies (adjusted to be nonzero).
 *
 * This function may be called either with or without dev->power.lock held.
 * Either way it can be racy, since power.last_busy may be updated at any time.
 */
unsigned long pm_runtime_autosuspend_expiration(struct device *dev)
{
	int autosuspend_delay;
	long elapsed;
	unsigned long last_busy;
	unsigned long expires = 0;

	if (!dev->power.use_autosuspend)
		goto out;

	autosuspend_delay = ACCESS_ONCE(dev->power.autosuspend_delay);
	if (autosuspend_delay < 0)
		goto out;

	last_busy = ACCESS_ONCE(dev->power.last_busy);
	elapsed = jiffies - last_busy;
	if (elapsed < 0)
		goto out;	/* jiffies has wrapped around. */

	/*