PM / Sleep: Add user space interface for manipulating wakeup sources, v3
[linux-2.6.git] / 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
15 static suspend_state_t autosleep_state;
16 static 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  */
23 static DEFINE_MUTEX(autosleep_lock);
24 static struct wakeup_source *autosleep_ws;
25
26 static 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
65 static DECLARE_WORK(suspend_work, try_to_suspend);
66
67 void 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
73 suspend_state_t pm_autosleep_state(void)
74 {
75         return autosleep_state;
76 }
77
78 int pm_autosleep_lock(void)
79 {
80         return mutex_lock_interruptible(&autosleep_lock);
81 }
82
83 void pm_autosleep_unlock(void)
84 {
85         mutex_unlock(&autosleep_lock);
86 }
87
88 int 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
115 int __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 }