Root/kernel/power/autosleep.c

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        mutex_unlock(&autosleep_lock);
37        goto out;
38    }
39
40    if (autosleep_state == PM_SUSPEND_ON) {
41        mutex_unlock(&autosleep_lock);
42        return;
43    }
44    if (autosleep_state >= PM_SUSPEND_MAX)
45        hibernate();
46    else
47        pm_suspend(autosleep_state);
48
49    mutex_unlock(&autosleep_lock);
50
51    if (!pm_get_wakeup_count(&final_count, false))
52        goto out;
53
54    /*
55     * If the wakeup occured for an unknown reason, wait to prevent the
56     * system from trying to suspend and waking up in a tight loop.
57     */
58    if (final_count == initial_count)
59        schedule_timeout_uninterruptible(HZ / 2);
60
61 out:
62    queue_up_suspend_work();
63}
64
65static DECLARE_WORK(suspend_work, try_to_suspend);
66
67void queue_up_suspend_work(void)
68{
69    if (!work_pending(&suspend_work) && autosleep_state > PM_SUSPEND_ON)
70        queue_work(autosleep_wq, &suspend_work);
71}
72
73suspend_state_t pm_autosleep_state(void)
74{
75    return autosleep_state;
76}
77
78int pm_autosleep_lock(void)
79{
80    return mutex_lock_interruptible(&autosleep_lock);
81}
82
83void pm_autosleep_unlock(void)
84{
85    mutex_unlock(&autosleep_lock);
86}
87
88int pm_autosleep_set_state(suspend_state_t state)
89{
90
91#ifndef CONFIG_HIBERNATION
92    if (state >= PM_SUSPEND_MAX)
93        return -EINVAL;
94#endif
95
96    __pm_stay_awake(autosleep_ws);
97
98    mutex_lock(&autosleep_lock);
99
100    autosleep_state = state;
101
102    __pm_relax(autosleep_ws);
103
104    if (state > PM_SUSPEND_ON) {
105        pm_wakep_autosleep_enabled(true);
106        queue_up_suspend_work();
107    } else {
108        pm_wakep_autosleep_enabled(false);
109    }
110
111    mutex_unlock(&autosleep_lock);
112    return 0;
113}
114
115int __init pm_autosleep_init(void)
116{
117    autosleep_ws = wakeup_source_register("autosleep");
118    if (!autosleep_ws)
119        return -ENOMEM;
120
121    autosleep_wq = alloc_ordered_workqueue("autosleep", 0);
122    if (autosleep_wq)
123        return 0;
124
125    wakeup_source_unregister(autosleep_ws);
126    return -ENOMEM;
127}
128

Archive Download this file



interactive