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                 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 }