xref: /openbmc/linux/kernel/power/autosleep.c (revision e23feb16)
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 		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 
66 static DECLARE_WORK(suspend_work, try_to_suspend);
67 
68 void queue_up_suspend_work(void)
69 {
70 	if (autosleep_state > PM_SUSPEND_ON)
71 		queue_work(autosleep_wq, &suspend_work);
72 }
73 
74 suspend_state_t pm_autosleep_state(void)
75 {
76 	return autosleep_state;
77 }
78 
79 int pm_autosleep_lock(void)
80 {
81 	return mutex_lock_interruptible(&autosleep_lock);
82 }
83 
84 void pm_autosleep_unlock(void)
85 {
86 	mutex_unlock(&autosleep_lock);
87 }
88 
89 int 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 
116 int __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 }
129