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7483b4a4d9
Introduce a mechanism by which the kernel can trigger global transitions to a sleep state chosen by user space if there are no active wakeup sources. It consists of a new sysfs attribute, /sys/power/autosleep, that can be written one of the strings returned by reads from /sys/power/state, an ordered workqueue and a work item carrying out the "suspend" operations. If a string representing the system's sleep state is written to /sys/power/autosleep, the work item triggering transitions to that state is queued up and it requeues itself after every execution until user space writes "off" to /sys/power/autosleep. That work item enables the detection of wakeup events using the functions already defined in drivers/base/power/wakeup.c (with one small modification) and calls either pm_suspend(), or hibernate() to put the system into a sleep state. If a wakeup event is reported while the transition is in progress, it will abort the transition and the "system suspend" work item will be queued up again. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: NeilBrown <neilb@suse.de>
124 lines
2.5 KiB
C
124 lines
2.5 KiB
C
/*
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* kernel/power/autosleep.c
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*
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* Opportunistic sleep support.
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*
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* Copyright (C) 2012 Rafael J. Wysocki <rjw@sisk.pl>
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*/
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#include <linux/device.h>
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#include <linux/mutex.h>
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#include <linux/pm_wakeup.h>
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#include "power.h"
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static suspend_state_t autosleep_state;
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static struct workqueue_struct *autosleep_wq;
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/*
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* Note: it is only safe to mutex_lock(&autosleep_lock) if a wakeup_source
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* is active, otherwise a deadlock with try_to_suspend() is possible.
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* Alternatively mutex_lock_interruptible() can be used. This will then fail
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* if an auto_sleep cycle tries to freeze processes.
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*/
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static DEFINE_MUTEX(autosleep_lock);
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static struct wakeup_source *autosleep_ws;
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static void try_to_suspend(struct work_struct *work)
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{
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unsigned int initial_count, final_count;
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if (!pm_get_wakeup_count(&initial_count, true))
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goto out;
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mutex_lock(&autosleep_lock);
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if (!pm_save_wakeup_count(initial_count)) {
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mutex_unlock(&autosleep_lock);
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goto out;
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}
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if (autosleep_state == PM_SUSPEND_ON) {
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mutex_unlock(&autosleep_lock);
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return;
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}
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if (autosleep_state >= PM_SUSPEND_MAX)
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hibernate();
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else
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pm_suspend(autosleep_state);
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mutex_unlock(&autosleep_lock);
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if (!pm_get_wakeup_count(&final_count, false))
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goto out;
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/*
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* If the wakeup occured for an unknown reason, wait to prevent the
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* system from trying to suspend and waking up in a tight loop.
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*/
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if (final_count == initial_count)
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schedule_timeout_uninterruptible(HZ / 2);
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out:
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queue_up_suspend_work();
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}
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static DECLARE_WORK(suspend_work, try_to_suspend);
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void queue_up_suspend_work(void)
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{
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if (!work_pending(&suspend_work) && autosleep_state > PM_SUSPEND_ON)
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queue_work(autosleep_wq, &suspend_work);
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}
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suspend_state_t pm_autosleep_state(void)
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{
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return autosleep_state;
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}
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int pm_autosleep_lock(void)
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{
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return mutex_lock_interruptible(&autosleep_lock);
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}
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void pm_autosleep_unlock(void)
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{
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mutex_unlock(&autosleep_lock);
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}
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int pm_autosleep_set_state(suspend_state_t state)
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{
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#ifndef CONFIG_HIBERNATION
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if (state >= PM_SUSPEND_MAX)
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return -EINVAL;
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#endif
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__pm_stay_awake(autosleep_ws);
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mutex_lock(&autosleep_lock);
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autosleep_state = state;
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__pm_relax(autosleep_ws);
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if (state > PM_SUSPEND_ON)
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queue_up_suspend_work();
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mutex_unlock(&autosleep_lock);
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return 0;
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}
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int __init pm_autosleep_init(void)
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{
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autosleep_ws = wakeup_source_register("autosleep");
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if (!autosleep_ws)
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return -ENOMEM;
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autosleep_wq = alloc_ordered_workqueue("autosleep", 0);
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if (autosleep_wq)
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return 0;
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wakeup_source_unregister(autosleep_ws);
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return -ENOMEM;
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}
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