From 7483b4a4d9abf9dcf1ffe6e805ead2847ec3264e Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Sun, 29 Apr 2012 22:53:22 +0200 Subject: PM / Sleep: Implement opportunistic sleep, v2 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 Acked-by: Greg Kroah-Hartman Reviewed-by: NeilBrown --- kernel/power/autosleep.c | 123 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 123 insertions(+) create mode 100644 kernel/power/autosleep.c (limited to 'kernel/power/autosleep.c') diff --git a/kernel/power/autosleep.c b/kernel/power/autosleep.c new file mode 100644 index 000000000000..42348e3589d3 --- /dev/null +++ b/kernel/power/autosleep.c @@ -0,0 +1,123 @@ +/* + * kernel/power/autosleep.c + * + * Opportunistic sleep support. + * + * Copyright (C) 2012 Rafael J. Wysocki + */ + +#include +#include +#include + +#include "power.h" + +static suspend_state_t autosleep_state; +static struct workqueue_struct *autosleep_wq; +/* + * Note: it is only safe to mutex_lock(&autosleep_lock) if a wakeup_source + * is active, otherwise a deadlock with try_to_suspend() is possible. + * Alternatively mutex_lock_interruptible() can be used. This will then fail + * if an auto_sleep cycle tries to freeze processes. + */ +static DEFINE_MUTEX(autosleep_lock); +static struct wakeup_source *autosleep_ws; + +static void try_to_suspend(struct work_struct *work) +{ + unsigned int initial_count, final_count; + + if (!pm_get_wakeup_count(&initial_count, true)) + goto out; + + mutex_lock(&autosleep_lock); + + if (!pm_save_wakeup_count(initial_count)) { + mutex_unlock(&autosleep_lock); + goto out; + } + + if (autosleep_state == PM_SUSPEND_ON) { + mutex_unlock(&autosleep_lock); + return; + } + if (autosleep_state >= PM_SUSPEND_MAX) + hibernate(); + else + pm_suspend(autosleep_state); + + mutex_unlock(&autosleep_lock); + + if (!pm_get_wakeup_count(&final_count, false)) + goto out; + + /* + * If the wakeup occured for an unknown reason, wait to prevent the + * system from trying to suspend and waking up in a tight loop. + */ + if (final_count == initial_count) + schedule_timeout_uninterruptible(HZ / 2); + + out: + queue_up_suspend_work(); +} + +static DECLARE_WORK(suspend_work, try_to_suspend); + +void queue_up_suspend_work(void) +{ + if (!work_pending(&suspend_work) && autosleep_state > PM_SUSPEND_ON) + queue_work(autosleep_wq, &suspend_work); +} + +suspend_state_t pm_autosleep_state(void) +{ + return autosleep_state; +} + +int pm_autosleep_lock(void) +{ + return mutex_lock_interruptible(&autosleep_lock); +} + +void pm_autosleep_unlock(void) +{ + mutex_unlock(&autosleep_lock); +} + +int pm_autosleep_set_state(suspend_state_t state) +{ + +#ifndef CONFIG_HIBERNATION + if (state >= PM_SUSPEND_MAX) + return -EINVAL; +#endif + + __pm_stay_awake(autosleep_ws); + + mutex_lock(&autosleep_lock); + + autosleep_state = state; + + __pm_relax(autosleep_ws); + + if (state > PM_SUSPEND_ON) + queue_up_suspend_work(); + + mutex_unlock(&autosleep_lock); + return 0; +} + +int __init pm_autosleep_init(void) +{ + autosleep_ws = wakeup_source_register("autosleep"); + if (!autosleep_ws) + return -ENOMEM; + + autosleep_wq = alloc_ordered_workqueue("autosleep", 0); + if (autosleep_wq) + return 0; + + wakeup_source_unregister(autosleep_ws); + return -ENOMEM; +} -- cgit v1.2.3