xref: /openbmc/linux/kernel/power/autosleep.c (revision e4b2897a) 
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * kernel/power/autosleep.c
4  *
5  * Opportunistic sleep support.
6  *
7  * Copyright (C) 2012 Rafael J. Wysocki <rjw@sisk.pl>
8  */
9 
10 #include <linux/device.h>
11 #include <linux/mutex.h>
12 #include <linux/pm_wakeup.h>
13 
14 #include "power.h"
15 
16 static suspend_state_t autosleep_state;
17 static struct workqueue_struct *autosleep_wq;
18 /*
19  * Note: it is only safe to mutex_lock(&autosleep_lock) if a wakeup_source
20  * is active, otherwise a deadlock with try_to_suspend() is possible.
21  * Alternatively mutex_lock_interruptible() can be used.  This will then fail
22  * if an auto_sleep cycle tries to freeze processes.
23  */
24 static DEFINE_MUTEX(autosleep_lock);
25 static struct wakeup_source *autosleep_ws;
26 
try_to_suspend(struct work_struct * work)27 static void try_to_suspend(struct work_struct *work)
28 {
29 	unsigned int initial_count, final_count;
30 
31 	if (!pm_get_wakeup_count(&initial_count, true))
32 		goto out;
33 
34 	mutex_lock(&autosleep_lock);
35 
36 	if (!pm_save_wakeup_count(initial_count) ||
37 		system_state != SYSTEM_RUNNING) {
38 		mutex_unlock(&autosleep_lock);
39 		goto out;
40 	}
41 
42 	if (autosleep_state == PM_SUSPEND_ON) {
43 		mutex_unlock(&autosleep_lock);
44 		return;
45 	}
46 	if (autosleep_state >= PM_SUSPEND_MAX)
47 		hibernate();
48 	else
49 		pm_suspend(autosleep_state);
50 
51 	mutex_unlock(&autosleep_lock);
52 
53 	if (!pm_get_wakeup_count(&final_count, false))
54 		goto out;
55 
56 	/*
57 	 * If the wakeup occurred for an unknown reason, wait to prevent the
58 	 * system from trying to suspend and waking up in a tight loop.
59 	 */
60 	if (final_count == initial_count)
61 		schedule_timeout_uninterruptible(HZ / 2);
62 
63  out:
64 	queue_up_suspend_work();
65 }
66 
67 static DECLARE_WORK(suspend_work, try_to_suspend);
68 
queue_up_suspend_work(void)69 void queue_up_suspend_work(void)
70 {
71 	if (autosleep_state > PM_SUSPEND_ON)
72 		queue_work(autosleep_wq, &suspend_work);
73 }
74 
pm_autosleep_state(void)75 suspend_state_t pm_autosleep_state(void)
76 {
77 	return autosleep_state;
78 }
79 
pm_autosleep_lock(void)80 int pm_autosleep_lock(void)
81 {
82 	return mutex_lock_interruptible(&autosleep_lock);
83 }
84 
pm_autosleep_unlock(void)85 void pm_autosleep_unlock(void)
86 {
87 	mutex_unlock(&autosleep_lock);
88 }
89 
pm_autosleep_set_state(suspend_state_t state)90 int pm_autosleep_set_state(suspend_state_t state)
91 {
92 
93 #ifndef CONFIG_HIBERNATION
94 	if (state >= PM_SUSPEND_MAX)
95 		return -EINVAL;
96 #endif
97 
98 	__pm_stay_awake(autosleep_ws);
99 
100 	mutex_lock(&autosleep_lock);
101 
102 	autosleep_state = state;
103 
104 	__pm_relax(autosleep_ws);
105 
106 	if (state > PM_SUSPEND_ON) {
107 		pm_wakep_autosleep_enabled(true);
108 		queue_up_suspend_work();
109 	} else {
110 		pm_wakep_autosleep_enabled(false);
111 	}
112 
113 	mutex_unlock(&autosleep_lock);
114 	return 0;
115 }
116 
pm_autosleep_init(void)117 int __init pm_autosleep_init(void)
118 {
119 	autosleep_ws = wakeup_source_register(NULL, "autosleep");
120 	if (!autosleep_ws)
121 		return -ENOMEM;
122 
123 	autosleep_wq = alloc_ordered_workqueue("autosleep", 0);
124 	if (autosleep_wq)
125 		return 0;
126 
127 	wakeup_source_unregister(autosleep_ws);
128 	return -ENOMEM;
129 }
130