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