PM / sleep: Asynchronous threads for suspend_noirq

[linux/fpc-iii.git] / drivers / base / power / wakeup.c

/*
 * drivers/base/power/wakeup.c - System wakeup events framework
 *
 * Copyright (c) 2010 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
 *
 * This file is released under the GPLv2.
 */

#include <linux/device.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/capability.h>
#include <linux/export.h>
#include <linux/suspend.h>
#include <linux/seq_file.h>
#include <linux/debugfs.h>
#include <trace/events/power.h>

#include "power.h"

/*
 * If set, the suspend/hibernate code will abort transitions to a sleep state
 * if wakeup events are registered during or immediately before the transition.
 */
bool events_check_enabled __read_mostly;

/*
 * Combined counters of registered wakeup events and wakeup events in progress.
 * They need to be modified together atomically, so it's better to use one
 * atomic variable to hold them both.
 */
static atomic_t combined_event_count = ATOMIC_INIT(0);

#define IN_PROGRESS_BITS        (sizeof(int) * 4)
#define MAX_IN_PROGRESS         ((1 << IN_PROGRESS_BITS) - 1)

static void split_counters(unsigned int *cnt, unsigned int *inpr)
{
        unsigned int comb = atomic_read(&combined_event_count);

        *cnt = (comb >> IN_PROGRESS_BITS);
        *inpr = comb & MAX_IN_PROGRESS;
}

/* A preserved old value of the events counter. */
static unsigned int saved_count;

static DEFINE_SPINLOCK(events_lock);

static void pm_wakeup_timer_fn(unsigned long data);

static LIST_HEAD(wakeup_sources);

static DECLARE_WAIT_QUEUE_HEAD(wakeup_count_wait_queue);

/**
 * wakeup_source_prepare - Prepare a new wakeup source for initialization.
 * @ws: Wakeup source to prepare.
 * @name: Pointer to the name of the new wakeup source.
 *
 * Callers must ensure that the @name string won't be freed when @ws is still in
 * use.
 */
void wakeup_source_prepare(struct wakeup_source *ws, const char *name)
{
        if (ws) {
                memset(ws, 0, sizeof(*ws));
                ws->name = name;
        }
}
EXPORT_SYMBOL_GPL(wakeup_source_prepare);

/**
 * wakeup_source_create - Create a struct wakeup_source object.
 * @name: Name of the new wakeup source.
 */
struct wakeup_source *wakeup_source_create(const char *name)
{
        struct wakeup_source *ws;

        ws = kmalloc(sizeof(*ws), GFP_KERNEL);
        if (!ws)
                return NULL;

        wakeup_source_prepare(ws, name ? kstrdup(name, GFP_KERNEL) : NULL);
        return ws;
}
EXPORT_SYMBOL_GPL(wakeup_source_create);

/**
 * wakeup_source_drop - Prepare a struct wakeup_source object for destruction.
 * @ws: Wakeup source to prepare for destruction.
 *
 * Callers must ensure that __pm_stay_awake() or __pm_wakeup_event() will never
 * be run in parallel with this function for the same wakeup source object.
 */
void wakeup_source_drop(struct wakeup_source *ws)
{
        if (!ws)
                return;

        del_timer_sync(&ws->timer);
        __pm_relax(ws);
}
EXPORT_SYMBOL_GPL(wakeup_source_drop);

/**
 * wakeup_source_destroy - Destroy a struct wakeup_source object.
 * @ws: Wakeup source to destroy.
 *
 * Use only for wakeup source objects created with wakeup_source_create().
 */
void wakeup_source_destroy(struct wakeup_source *ws)
{
        if (!ws)
                return;

        wakeup_source_drop(ws);
        kfree(ws->name);
        kfree(ws);
}
EXPORT_SYMBOL_GPL(wakeup_source_destroy);

/**
 * wakeup_source_add - Add given object to the list of wakeup sources.
 * @ws: Wakeup source object to add to the list.
 */
void wakeup_source_add(struct wakeup_source *ws)
{
        unsigned long flags;

        if (WARN_ON(!ws))
                return;

        spin_lock_init(&ws->lock);
        setup_timer(&ws->timer, pm_wakeup_timer_fn, (unsigned long)ws);
        ws->active = false;
        ws->last_time = ktime_get();

        spin_lock_irqsave(&events_lock, flags);
        list_add_rcu(&ws->entry, &wakeup_sources);
        spin_unlock_irqrestore(&events_lock, flags);
}
EXPORT_SYMBOL_GPL(wakeup_source_add);

/**
 * wakeup_source_remove - Remove given object from the wakeup sources list.
 * @ws: Wakeup source object to remove from the list.
 */
void wakeup_source_remove(struct wakeup_source *ws)
{
        unsigned long flags;

        if (WARN_ON(!ws))
                return;

        spin_lock_irqsave(&events_lock, flags);
        list_del_rcu(&ws->entry);
        spin_unlock_irqrestore(&events_lock, flags);
        synchronize_rcu();
}
EXPORT_SYMBOL_GPL(wakeup_source_remove);

/**
 * wakeup_source_register - Create wakeup source and add it to the list.
 * @name: Name of the wakeup source to register.
 */
struct wakeup_source *wakeup_source_register(const char *name)
{
        struct wakeup_source *ws;

        ws = wakeup_source_create(name);
        if (ws)
                wakeup_source_add(ws);

        return ws;
}
EXPORT_SYMBOL_GPL(wakeup_source_register);

/**
 * wakeup_source_unregister - Remove wakeup source from the list and remove it.
 * @ws: Wakeup source object to unregister.
 */
void wakeup_source_unregister(struct wakeup_source *ws)
{
        if (ws) {
                wakeup_source_remove(ws);
                wakeup_source_destroy(ws);
        }
}
EXPORT_SYMBOL_GPL(wakeup_source_unregister);

/**
 * device_wakeup_attach - Attach a wakeup source object to a device object.
 * @dev: Device to handle.
 * @ws: Wakeup source object to attach to @dev.
 *
 * This causes @dev to be treated as a wakeup device.
 */
static int device_wakeup_attach(struct device *dev, struct wakeup_source *ws)
{
        spin_lock_irq(&dev->power.lock);
        if (dev->power.wakeup) {
                spin_unlock_irq(&dev->power.lock);
                return -EEXIST;
        }
        dev->power.wakeup = ws;
        spin_unlock_irq(&dev->power.lock);
        return 0;
}

/**
 * device_wakeup_enable - Enable given device to be a wakeup source.
 * @dev: Device to handle.
 *
 * Create a wakeup source object, register it and attach it to @dev.
 */
int device_wakeup_enable(struct device *dev)
{
        struct wakeup_source *ws;
        int ret;

        if (!dev || !dev->power.can_wakeup)
                return -EINVAL;

        ws = wakeup_source_register(dev_name(dev));
        if (!ws)
                return -ENOMEM;

        ret = device_wakeup_attach(dev, ws);
        if (ret)
                wakeup_source_unregister(ws);

        return ret;
}
EXPORT_SYMBOL_GPL(device_wakeup_enable);

/**
 * device_wakeup_detach - Detach a device's wakeup source object from it.
 * @dev: Device to detach the wakeup source object from.
 *
 * After it returns, @dev will not be treated as a wakeup device any more.
 */
static struct wakeup_source *device_wakeup_detach(struct device *dev)
{
        struct wakeup_source *ws;

        spin_lock_irq(&dev->power.lock);
        ws = dev->power.wakeup;
        dev->power.wakeup = NULL;
        spin_unlock_irq(&dev->power.lock);
        return ws;
}

/**
 * device_wakeup_disable - Do not regard a device as a wakeup source any more.
 * @dev: Device to handle.
 *
 * Detach the @dev's wakeup source object from it, unregister this wakeup source
 * object and destroy it.
 */
int device_wakeup_disable(struct device *dev)
{
        struct wakeup_source *ws;

        if (!dev || !dev->power.can_wakeup)
                return -EINVAL;

        ws = device_wakeup_detach(dev);
        if (ws)
                wakeup_source_unregister(ws);

        return 0;
}
EXPORT_SYMBOL_GPL(device_wakeup_disable);

/**
 * device_set_wakeup_capable - Set/reset device wakeup capability flag.
 * @dev: Device to handle.
 * @capable: Whether or not @dev is capable of waking up the system from sleep.
 *
 * If @capable is set, set the @dev's power.can_wakeup flag and add its
 * wakeup-related attributes to sysfs.  Otherwise, unset the @dev's
 * power.can_wakeup flag and remove its wakeup-related attributes from sysfs.
 *
 * This function may sleep and it can't be called from any context where
 * sleeping is not allowed.
 */
void device_set_wakeup_capable(struct device *dev, bool capable)
{
        if (!!dev->power.can_wakeup == !!capable)
                return;

        if (device_is_registered(dev) && !list_empty(&dev->power.entry)) {
                if (capable) {
                        if (wakeup_sysfs_add(dev))
                                return;
                } else {
                        wakeup_sysfs_remove(dev);
                }
        }
        dev->power.can_wakeup = capable;
}
EXPORT_SYMBOL_GPL(device_set_wakeup_capable);

/**
 * device_init_wakeup - Device wakeup initialization.
 * @dev: Device to handle.
 * @enable: Whether or not to enable @dev as a wakeup device.
 *
 * By default, most devices should leave wakeup disabled.  The exceptions are
 * devices that everyone expects to be wakeup sources: keyboards, power buttons,
 * possibly network interfaces, etc.  Also, devices that don't generate their
 * own wakeup requests but merely forward requests from one bus to another
 * (like PCI bridges) should have wakeup enabled by default.
 */
int device_init_wakeup(struct device *dev, bool enable)
{
        int ret = 0;

        if (enable) {
                device_set_wakeup_capable(dev, true);
                ret = device_wakeup_enable(dev);
        } else {
                device_set_wakeup_capable(dev, false);
        }

        return ret;
}
EXPORT_SYMBOL_GPL(device_init_wakeup);

/**
 * device_set_wakeup_enable - Enable or disable a device to wake up the system.
 * @dev: Device to handle.
 */
int device_set_wakeup_enable(struct device *dev, bool enable)
{
        if (!dev || !dev->power.can_wakeup)
                return -EINVAL;

        return enable ? device_wakeup_enable(dev) : device_wakeup_disable(dev);
}
EXPORT_SYMBOL_GPL(device_set_wakeup_enable);

/*
 * The functions below use the observation that each wakeup event starts a
 * period in which the system should not be suspended.  The moment this period
 * will end depends on how the wakeup event is going to be processed after being
 * detected and all of the possible cases can be divided into two distinct
 * groups.
 *
 * First, a wakeup event may be detected by the same functional unit that will
 * carry out the entire processing of it and possibly will pass it to user space
 * for further processing.  In that case the functional unit that has detected
 * the event may later "close" the "no suspend" period associated with it
 * directly as soon as it has been dealt with.  The pair of pm_stay_awake() and
 * pm_relax(), balanced with each other, is supposed to be used in such
 * situations.
 *
 * Second, a wakeup event may be detected by one functional unit and processed
 * by another one.  In that case the unit that has detected it cannot really
 * "close" the "no suspend" period associated with it, unless it knows in
 * advance what's going to happen to the event during processing.  This
 * knowledge, however, may not be available to it, so it can simply specify time
 * to wait before the system can be suspended and pass it as the second
 * argument of pm_wakeup_event().
 *
 * It is valid to call pm_relax() after pm_wakeup_event(), in which case the
 * "no suspend" period will be ended either by the pm_relax(), or by the timer
 * function executed when the timer expires, whichever comes first.
 */

/**
 * wakup_source_activate - Mark given wakeup source as active.
 * @ws: Wakeup source to handle.
 *
 * Update the @ws' statistics and, if @ws has just been activated, notify the PM
 * core of the event by incrementing the counter of of wakeup events being
 * processed.
 */
static void wakeup_source_activate(struct wakeup_source *ws)
{
        unsigned int cec;

        /*
         * active wakeup source should bring the system
         * out of PM_SUSPEND_FREEZE state
         */
        freeze_wake();

        ws->active = true;
        ws->active_count++;
        ws->last_time = ktime_get();
        if (ws->autosleep_enabled)
                ws->start_prevent_time = ws->last_time;

        /* Increment the counter of events in progress. */
        cec = atomic_inc_return(&combined_event_count);

        trace_wakeup_source_activate(ws->name, cec);
}

/**
 * wakeup_source_report_event - Report wakeup event using the given source.
 * @ws: Wakeup source to report the event for.
 */
static void wakeup_source_report_event(struct wakeup_source *ws)
{
        ws->event_count++;
        /* This is racy, but the counter is approximate anyway. */
        if (events_check_enabled)
                ws->wakeup_count++;

        if (!ws->active)
                wakeup_source_activate(ws);
}

/**
 * __pm_stay_awake - Notify the PM core of a wakeup event.
 * @ws: Wakeup source object associated with the source of the event.
 *
 * It is safe to call this function from interrupt context.
 */
void __pm_stay_awake(struct wakeup_source *ws)
{
        unsigned long flags;

        if (!ws)
                return;

        spin_lock_irqsave(&ws->lock, flags);

        wakeup_source_report_event(ws);
        del_timer(&ws->timer);
        ws->timer_expires = 0;

        spin_unlock_irqrestore(&ws->lock, flags);
}
EXPORT_SYMBOL_GPL(__pm_stay_awake);

/**
 * pm_stay_awake - Notify the PM core that a wakeup event is being processed.
 * @dev: Device the wakeup event is related to.
 *
 * Notify the PM core of a wakeup event (signaled by @dev) by calling
 * __pm_stay_awake for the @dev's wakeup source object.
 *
 * Call this function after detecting of a wakeup event if pm_relax() is going
 * to be called directly after processing the event (and possibly passing it to
 * user space for further processing).
 */
void pm_stay_awake(struct device *dev)
{
        unsigned long flags;

        if (!dev)
                return;

        spin_lock_irqsave(&dev->power.lock, flags);
        __pm_stay_awake(dev->power.wakeup);
        spin_unlock_irqrestore(&dev->power.lock, flags);
}
EXPORT_SYMBOL_GPL(pm_stay_awake);

#ifdef CONFIG_PM_AUTOSLEEP
static void update_prevent_sleep_time(struct wakeup_source *ws, ktime_t now)
{
        ktime_t delta = ktime_sub(now, ws->start_prevent_time);
        ws->prevent_sleep_time = ktime_add(ws->prevent_sleep_time, delta);
}
#else
static inline void update_prevent_sleep_time(struct wakeup_source *ws,
                                             ktime_t now) {}
#endif

/**
 * wakup_source_deactivate - Mark given wakeup source as inactive.
 * @ws: Wakeup source to handle.
 *
 * Update the @ws' statistics and notify the PM core that the wakeup source has
 * become inactive by decrementing the counter of wakeup events being processed
 * and incrementing the counter of registered wakeup events.
 */
static void wakeup_source_deactivate(struct wakeup_source *ws)
{
        unsigned int cnt, inpr, cec;
        ktime_t duration;
        ktime_t now;

        ws->relax_count++;
        /*
         * __pm_relax() may be called directly or from a timer function.
         * If it is called directly right after the timer function has been
         * started, but before the timer function calls __pm_relax(), it is
         * possible that __pm_stay_awake() will be called in the meantime and
         * will set ws->active.  Then, ws->active may be cleared immediately
         * by the __pm_relax() called from the timer function, but in such a
         * case ws->relax_count will be different from ws->active_count.
         */
        if (ws->relax_count != ws->active_count) {
                ws->relax_count--;
                return;
        }

        ws->active = false;

        now = ktime_get();
        duration = ktime_sub(now, ws->last_time);
        ws->total_time = ktime_add(ws->total_time, duration);
        if (ktime_to_ns(duration) > ktime_to_ns(ws->max_time))
                ws->max_time = duration;

        ws->last_time = now;
        del_timer(&ws->timer);
        ws->timer_expires = 0;

        if (ws->autosleep_enabled)
                update_prevent_sleep_time(ws, now);

        /*
         * Increment the counter of registered wakeup events and decrement the
         * couter of wakeup events in progress simultaneously.
         */
        cec = atomic_add_return(MAX_IN_PROGRESS, &combined_event_count);
        trace_wakeup_source_deactivate(ws->name, cec);

        split_counters(&cnt, &inpr);
        if (!inpr && waitqueue_active(&wakeup_count_wait_queue))
                wake_up(&wakeup_count_wait_queue);
}

/**
 * __pm_relax - Notify the PM core that processing of a wakeup event has ended.
 * @ws: Wakeup source object associated with the source of the event.
 *
 * Call this function for wakeup events whose processing started with calling
 * __pm_stay_awake().
 *
 * It is safe to call it from interrupt context.
 */
void __pm_relax(struct wakeup_source *ws)
{
        unsigned long flags;

        if (!ws)
                return;

        spin_lock_irqsave(&ws->lock, flags);
        if (ws->active)
                wakeup_source_deactivate(ws);
        spin_unlock_irqrestore(&ws->lock, flags);
}
EXPORT_SYMBOL_GPL(__pm_relax);

/**
 * pm_relax - Notify the PM core that processing of a wakeup event has ended.
 * @dev: Device that signaled the event.
 *
 * Execute __pm_relax() for the @dev's wakeup source object.
 */
void pm_relax(struct device *dev)
{
        unsigned long flags;

        if (!dev)
                return;

        spin_lock_irqsave(&dev->power.lock, flags);
        __pm_relax(dev->power.wakeup);
        spin_unlock_irqrestore(&dev->power.lock, flags);
}
EXPORT_SYMBOL_GPL(pm_relax);

/**
 * pm_wakeup_timer_fn - Delayed finalization of a wakeup event.
 * @data: Address of the wakeup source object associated with the event source.
 *
 * Call wakeup_source_deactivate() for the wakeup source whose address is stored
 * in @data if it is currently active and its timer has not been canceled and
 * the expiration time of the timer is not in future.
 */
static void pm_wakeup_timer_fn(unsigned long data)
{
        struct wakeup_source *ws = (struct wakeup_source *)data;
        unsigned long flags;

        spin_lock_irqsave(&ws->lock, flags);

        if (ws->active && ws->timer_expires
            && time_after_eq(jiffies, ws->timer_expires)) {
                wakeup_source_deactivate(ws);
                ws->expire_count++;
        }

        spin_unlock_irqrestore(&ws->lock, flags);
}

/**
 * __pm_wakeup_event - Notify the PM core of a wakeup event.
 * @ws: Wakeup source object associated with the event source.
 * @msec: Anticipated event processing time (in milliseconds).
 *
 * Notify the PM core of a wakeup event whose source is @ws that will take
 * approximately @msec milliseconds to be processed by the kernel.  If @ws is
 * not active, activate it.  If @msec is nonzero, set up the @ws' timer to
 * execute pm_wakeup_timer_fn() in future.
 *
 * It is safe to call this function from interrupt context.
 */
void __pm_wakeup_event(struct wakeup_source *ws, unsigned int msec)
{
        unsigned long flags;
        unsigned long expires;

        if (!ws)
                return;

        spin_lock_irqsave(&ws->lock, flags);

        wakeup_source_report_event(ws);

        if (!msec) {
                wakeup_source_deactivate(ws);
                goto unlock;
        }

        expires = jiffies + msecs_to_jiffies(msec);
        if (!expires)
                expires = 1;

        if (!ws->timer_expires || time_after(expires, ws->timer_expires)) {
                mod_timer(&ws->timer, expires);
                ws->timer_expires = expires;
        }

 unlock:
        spin_unlock_irqrestore(&ws->lock, flags);
}
EXPORT_SYMBOL_GPL(__pm_wakeup_event);


/**
 * pm_wakeup_event - Notify the PM core of a wakeup event.
 * @dev: Device the wakeup event is related to.
 * @msec: Anticipated event processing time (in milliseconds).
 *
 * Call __pm_wakeup_event() for the @dev's wakeup source object.
 */
void pm_wakeup_event(struct device *dev, unsigned int msec)
{
        unsigned long flags;

        if (!dev)
                return;

        spin_lock_irqsave(&dev->power.lock, flags);
        __pm_wakeup_event(dev->power.wakeup, msec);
        spin_unlock_irqrestore(&dev->power.lock, flags);
}
EXPORT_SYMBOL_GPL(pm_wakeup_event);

void pm_print_active_wakeup_sources(void)
{
        struct wakeup_source *ws;
        int active = 0;
        struct wakeup_source *last_activity_ws = NULL;

        rcu_read_lock();
        list_for_each_entry_rcu(ws, &wakeup_sources, entry) {
                if (ws->active) {
                        pr_info("active wakeup source: %s\n", ws->name);
                        active = 1;
                } else if (!active &&
                           (!last_activity_ws ||
                            ktime_to_ns(ws->last_time) >
                            ktime_to_ns(last_activity_ws->last_time))) {
                        last_activity_ws = ws;
                }
        }

        if (!active && last_activity_ws)
                pr_info("last active wakeup source: %s\n",
                        last_activity_ws->name);
        rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(pm_print_active_wakeup_sources);

/**
 * pm_wakeup_pending - Check if power transition in progress should be aborted.
 *
 * Compare the current number of registered wakeup events with its preserved
 * value from the past and return true if new wakeup events have been registered
 * since the old value was stored.  Also return true if the current number of
 * wakeup events being processed is different from zero.
 */
bool pm_wakeup_pending(void)
{
        unsigned long flags;
        bool ret = false;

        spin_lock_irqsave(&events_lock, flags);
        if (events_check_enabled) {
                unsigned int cnt, inpr;

                split_counters(&cnt, &inpr);
                ret = (cnt != saved_count || inpr > 0);
                events_check_enabled = !ret;
        }
        spin_unlock_irqrestore(&events_lock, flags);

        if (ret) {
                pr_info("PM: Wakeup pending, aborting suspend\n");
                pm_print_active_wakeup_sources();
        }

        return ret;
}

/**
 * pm_get_wakeup_count - Read the number of registered wakeup events.
 * @count: Address to store the value at.
 * @block: Whether or not to block.
 *
 * Store the number of registered wakeup events at the address in @count.  If
 * @block is set, block until the current number of wakeup events being
 * processed is zero.
 *
 * Return 'false' if the current number of wakeup events being processed is
 * nonzero.  Otherwise return 'true'.
 */
bool pm_get_wakeup_count(unsigned int *count, bool block)
{
        unsigned int cnt, inpr;

        if (block) {
                DEFINE_WAIT(wait);

                for (;;) {
                        prepare_to_wait(&wakeup_count_wait_queue, &wait,
                                        TASK_INTERRUPTIBLE);
                        split_counters(&cnt, &inpr);
                        if (inpr == 0 || signal_pending(current))
                                break;

                        schedule();
                }
                finish_wait(&wakeup_count_wait_queue, &wait);
        }

        split_counters(&cnt, &inpr);
        *count = cnt;
        return !inpr;
}

/**
 * pm_save_wakeup_count - Save the current number of registered wakeup events.
 * @count: Value to compare with the current number of registered wakeup events.
 *
 * If @count is equal to the current number of registered wakeup events and the
 * current number of wakeup events being processed is zero, store @count as the
 * old number of registered wakeup events for pm_check_wakeup_events(), enable
 * wakeup events detection and return 'true'.  Otherwise disable wakeup events
 * detection and return 'false'.
 */
bool pm_save_wakeup_count(unsigned int count)
{
        unsigned int cnt, inpr;
        unsigned long flags;

        events_check_enabled = false;
        spin_lock_irqsave(&events_lock, flags);
        split_counters(&cnt, &inpr);
        if (cnt == count && inpr == 0) {
                saved_count = count;
                events_check_enabled = true;
        }
        spin_unlock_irqrestore(&events_lock, flags);
        return events_check_enabled;
}

#ifdef CONFIG_PM_AUTOSLEEP
/**
 * pm_wakep_autosleep_enabled - Modify autosleep_enabled for all wakeup sources.
 * @enabled: Whether to set or to clear the autosleep_enabled flags.
 */
void pm_wakep_autosleep_enabled(bool set)
{
        struct wakeup_source *ws;
        ktime_t now = ktime_get();

        rcu_read_lock();
        list_for_each_entry_rcu(ws, &wakeup_sources, entry) {
                spin_lock_irq(&ws->lock);
                if (ws->autosleep_enabled != set) {
                        ws->autosleep_enabled = set;
                        if (ws->active) {
                                if (set)
                                        ws->start_prevent_time = now;
                                else
                                        update_prevent_sleep_time(ws, now);
                        }
                }
                spin_unlock_irq(&ws->lock);
        }
        rcu_read_unlock();
}
#endif /* CONFIG_PM_AUTOSLEEP */

static struct dentry *wakeup_sources_stats_dentry;

/**
 * print_wakeup_source_stats - Print wakeup source statistics information.
 * @m: seq_file to print the statistics into.
 * @ws: Wakeup source object to print the statistics for.
 */
static int print_wakeup_source_stats(struct seq_file *m,
                                     struct wakeup_source *ws)
{
        unsigned long flags;
        ktime_t total_time;
        ktime_t max_time;
        unsigned long active_count;
        ktime_t active_time;
        ktime_t prevent_sleep_time;
        int ret;

        spin_lock_irqsave(&ws->lock, flags);

        total_time = ws->total_time;
        max_time = ws->max_time;
        prevent_sleep_time = ws->prevent_sleep_time;
        active_count = ws->active_count;
        if (ws->active) {
                ktime_t now = ktime_get();

                active_time = ktime_sub(now, ws->last_time);
                total_time = ktime_add(total_time, active_time);
                if (active_time.tv64 > max_time.tv64)
                        max_time = active_time;

                if (ws->autosleep_enabled)
                        prevent_sleep_time = ktime_add(prevent_sleep_time,
                                ktime_sub(now, ws->start_prevent_time));
        } else {
                active_time = ktime_set(0, 0);
        }

        ret = seq_printf(m, "%-12s\t%lu\t\t%lu\t\t%lu\t\t%lu\t\t"
                        "%lld\t\t%lld\t\t%lld\t\t%lld\t\t%lld\n",
                        ws->name, active_count, ws->event_count,
                        ws->wakeup_count, ws->expire_count,
                        ktime_to_ms(active_time), ktime_to_ms(total_time),
                        ktime_to_ms(max_time), ktime_to_ms(ws->last_time),
                        ktime_to_ms(prevent_sleep_time));

        spin_unlock_irqrestore(&ws->lock, flags);

        return ret;
}

/**
 * wakeup_sources_stats_show - Print wakeup sources statistics information.
 * @m: seq_file to print the statistics into.
 */
static int wakeup_sources_stats_show(struct seq_file *m, void *unused)
{
        struct wakeup_source *ws;

        seq_puts(m, "name\t\tactive_count\tevent_count\twakeup_count\t"
                "expire_count\tactive_since\ttotal_time\tmax_time\t"
                "last_change\tprevent_suspend_time\n");

        rcu_read_lock();
        list_for_each_entry_rcu(ws, &wakeup_sources, entry)
                print_wakeup_source_stats(m, ws);
        rcu_read_unlock();

        return 0;
}

static int wakeup_sources_stats_open(struct inode *inode, struct file *file)
{
        return single_open(file, wakeup_sources_stats_show, NULL);
}

static const struct file_operations wakeup_sources_stats_fops = {
        .owner = THIS_MODULE,
        .open = wakeup_sources_stats_open,
        .read = seq_read,
        .llseek = seq_lseek,
        .release = single_release,
};

static int __init wakeup_sources_debugfs_init(void)
{
        wakeup_sources_stats_dentry = debugfs_create_file("wakeup_sources",
                        S_IRUGO, NULL, NULL, &wakeup_sources_stats_fops);
        return 0;
}

postcore_initcall(wakeup_sources_debugfs_init);