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 (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 }