1/*
  2 * kernel/power/autosleep.c
  3 *
  4 * Opportunistic sleep support.
  5 *
  6 * Copyright (C) 2012 Rafael J. Wysocki <rjw@sisk.pl>
  7 */
  8
  9#include <linux/device.h>
 10#include <linux/mutex.h>
 11#include <linux/pm_wakeup.h>
 12
 13#include "power.h"
 14
 15static suspend_state_t autosleep_state;
 16static struct workqueue_struct *autosleep_wq;
 17/*
 18 * Note: it is only safe to mutex_lock(&autosleep_lock) if a wakeup_source
 19 * is active, otherwise a deadlock with try_to_suspend() is possible.
 20 * Alternatively mutex_lock_interruptible() can be used.  This will then fail
 21 * if an auto_sleep cycle tries to freeze processes.
 22 */
 23static DEFINE_MUTEX(autosleep_lock);
 24static struct wakeup_source *autosleep_ws;
 25
 26static void try_to_suspend(struct work_struct *work)
 27{
 28	unsigned int initial_count, final_count;
 29
 30	if (!pm_get_wakeup_count(&initial_count, true))
 31		goto out;
 32
 33	mutex_lock(&autosleep_lock);
 34
 35	if (!pm_save_wakeup_count(initial_count) ||
 36		system_state != SYSTEM_RUNNING) {
 37		mutex_unlock(&autosleep_lock);
 38		goto out;
 39	}
 40
 41	if (autosleep_state == PM_SUSPEND_ON) {
 42		mutex_unlock(&autosleep_lock);
 43		return;
 44	}
 45	if (autosleep_state >= PM_SUSPEND_MAX)
 46		hibernate();
 47	else
 48		pm_suspend(autosleep_state);
 49
 50	mutex_unlock(&autosleep_lock);
 51
 52	if (!pm_get_wakeup_count(&final_count, false))
 53		goto out;
 54
 55	/*
 56	 * If the wakeup occured for an unknown reason, wait to prevent the
 57	 * system from trying to suspend and waking up in a tight loop.
 58	 */
 59	if (final_count == initial_count)
 60		schedule_timeout_uninterruptible(HZ / 2);
 61
 62 out:
 63	queue_up_suspend_work();
 64}
 65
 66static DECLARE_WORK(suspend_work, try_to_suspend);
 67
 68void queue_up_suspend_work(void)
 69{
 70	if (autosleep_state > PM_SUSPEND_ON)
 71		queue_work(autosleep_wq, &suspend_work);
 72}
 73
 74suspend_state_t pm_autosleep_state(void)
 75{
 76	return autosleep_state;
 77}
 78
 79int pm_autosleep_lock(void)
 80{
 81	return mutex_lock_interruptible(&autosleep_lock);
 82}
 83
 84void pm_autosleep_unlock(void)
 85{
 86	mutex_unlock(&autosleep_lock);
 87}
 88
 89int pm_autosleep_set_state(suspend_state_t state)
 90{
 91
 92#ifndef CONFIG_HIBERNATION
 93	if (state >= PM_SUSPEND_MAX)
 94		return -EINVAL;
 95#endif
 96
 97	__pm_stay_awake(autosleep_ws);
 98
 99	mutex_lock(&autosleep_lock);
100
101	autosleep_state = state;
102
103	__pm_relax(autosleep_ws);
104
105	if (state > PM_SUSPEND_ON) {
106		pm_wakep_autosleep_enabled(true);
107		queue_up_suspend_work();
108	} else {
109		pm_wakep_autosleep_enabled(false);
110	}
111
112	mutex_unlock(&autosleep_lock);
113	return 0;
114}
115
116int __init pm_autosleep_init(void)
117{
118	autosleep_ws = wakeup_source_register("autosleep");
119	if (!autosleep_ws)
120		return -ENOMEM;
121
122	autosleep_wq = alloc_ordered_workqueue("autosleep", 0);
123	if (autosleep_wq)
124		return 0;
125
126	wakeup_source_unregister(autosleep_ws);
127	return -ENOMEM;
128}