// SPDX-License-Identifier: GPL-2.0
/*
 * kernel/power/autosleep.c
 *
 * Opportunistic sleep support.
 *
 * Copyright (C) 2012 Rafael J. Wysocki <rjw@sisk.pl>
 */

#include <linux/device.h>
#include <linux/mutex.h>

#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) ||
                system_state != SYSTEM_RUNNING) {
                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 occurred 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 (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) {
                pm_wakep_autosleep_enabled(true);
                queue_up_suspend_work();
        } else {
                pm_wakep_autosleep_enabled(false);
        }

        mutex_unlock(&autosleep_lock);
        return 0;
}

int __init pm_autosleep_init(void)
{
        autosleep_ws = wakeup_source_register(NULL, "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;
}