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