wakeup.c

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/*
 * drivers/base/power/wakeup.c - System wakeup events framework
 *
 * Copyright (c) 2010 Rafael J. Wysocki <[email protected]>, 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);

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);

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);

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);

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);

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);

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);

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);

void wakeup_source_unregister(struct wakeup_source *ws)
{
    if (ws) {
        wakeup_source_remove(ws);
        wakeup_source_destroy(ws);
    }
}
EXPORT_SYMBOL_GPL(wakeup_source_unregister);

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;
}

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);

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;
}

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);

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);

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);

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.
 */

static void wakeup_source_activate(struct wakeup_source *ws)
{
    unsigned int cec;

    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);
}

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);
}

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);

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

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);
}

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);

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);

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);
}

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);


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);

static void 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();
}

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)
        print_active_wakeup_sources();

    return ret;
}

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;
}

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

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;

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;
}

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);