Merge branches 'pm-cpuidle', 'pm-cpufreq', 'pm-domains' and 'pm-sleep'

[mirror_ubuntu-bionic-kernel.git] / drivers / base / power / domain.c

/*
 * drivers/base/power/domain.c - Common code related to device power domains.
 *
 * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
 *
 * This file is released under the GPLv2.
 */

#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/pm_domain.h>
#include <linux/pm_qos.h>
#include <linux/pm_clock.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/sched.h>
#include <linux/suspend.h>
#include <linux/export.h>

#include "power.h"

#define GENPD_RETRY_MAX_MS      250             /* Approximate */

#define GENPD_DEV_CALLBACK(genpd, type, callback, dev)          \
({                                                              \
        type (*__routine)(struct device *__d);                  \
        type __ret = (type)0;                                   \
                                                                \
        __routine = genpd->dev_ops.callback;                    \
        if (__routine) {                                        \
                __ret = __routine(dev);                         \
        }                                                       \
        __ret;                                                  \
})

static LIST_HEAD(gpd_list);
static DEFINE_MUTEX(gpd_list_lock);

/*
 * Get the generic PM domain for a particular struct device.
 * This validates the struct device pointer, the PM domain pointer,
 * and checks that the PM domain pointer is a real generic PM domain.
 * Any failure results in NULL being returned.
 */
struct generic_pm_domain *pm_genpd_lookup_dev(struct device *dev)
{
        struct generic_pm_domain *genpd = NULL, *gpd;

        if (IS_ERR_OR_NULL(dev) || IS_ERR_OR_NULL(dev->pm_domain))
                return NULL;

        mutex_lock(&gpd_list_lock);
        list_for_each_entry(gpd, &gpd_list, gpd_list_node) {
                if (&gpd->domain == dev->pm_domain) {
                        genpd = gpd;
                        break;
                }
        }
        mutex_unlock(&gpd_list_lock);

        return genpd;
}

/*
 * This should only be used where we are certain that the pm_domain
 * attached to the device is a genpd domain.
 */
static struct generic_pm_domain *dev_to_genpd(struct device *dev)
{
        if (IS_ERR_OR_NULL(dev->pm_domain))
                return ERR_PTR(-EINVAL);

        return pd_to_genpd(dev->pm_domain);
}

static int genpd_stop_dev(struct generic_pm_domain *genpd, struct device *dev)
{
        return GENPD_DEV_CALLBACK(genpd, int, stop, dev);
}

static int genpd_start_dev(struct generic_pm_domain *genpd, struct device *dev)
{
        return GENPD_DEV_CALLBACK(genpd, int, start, dev);
}

static bool genpd_sd_counter_dec(struct generic_pm_domain *genpd)
{
        bool ret = false;

        if (!WARN_ON(atomic_read(&genpd->sd_count) == 0))
                ret = !!atomic_dec_and_test(&genpd->sd_count);

        return ret;
}

static void genpd_sd_counter_inc(struct generic_pm_domain *genpd)
{
        atomic_inc(&genpd->sd_count);
        smp_mb__after_atomic();
}

static int genpd_power_on(struct generic_pm_domain *genpd, bool timed)
{
        ktime_t time_start;
        s64 elapsed_ns;
        int ret;

        if (!genpd->power_on)
                return 0;

        if (!timed)
                return genpd->power_on(genpd);

        time_start = ktime_get();
        ret = genpd->power_on(genpd);
        if (ret)
                return ret;

        elapsed_ns = ktime_to_ns(ktime_sub(ktime_get(), time_start));
        if (elapsed_ns <= genpd->power_on_latency_ns)
                return ret;

        genpd->power_on_latency_ns = elapsed_ns;
        genpd->max_off_time_changed = true;
        pr_debug("%s: Power-%s latency exceeded, new value %lld ns\n",
                 genpd->name, "on", elapsed_ns);

        return ret;
}

static int genpd_power_off(struct generic_pm_domain *genpd, bool timed)
{
        ktime_t time_start;
        s64 elapsed_ns;
        int ret;

        if (!genpd->power_off)
                return 0;

        if (!timed)
                return genpd->power_off(genpd);

        time_start = ktime_get();
        ret = genpd->power_off(genpd);
        if (ret == -EBUSY)
                return ret;

        elapsed_ns = ktime_to_ns(ktime_sub(ktime_get(), time_start));
        if (elapsed_ns <= genpd->power_off_latency_ns)
                return ret;

        genpd->power_off_latency_ns = elapsed_ns;
        genpd->max_off_time_changed = true;
        pr_debug("%s: Power-%s latency exceeded, new value %lld ns\n",
                 genpd->name, "off", elapsed_ns);

        return ret;
}

/**
 * genpd_queue_power_off_work - Queue up the execution of genpd_poweroff().
 * @genpd: PM domain to power off.
 *
 * Queue up the execution of genpd_poweroff() unless it's already been done
 * before.
 */
static void genpd_queue_power_off_work(struct generic_pm_domain *genpd)
{
        queue_work(pm_wq, &genpd->power_off_work);
}

/**
 * __genpd_poweron - Restore power to a given PM domain and its masters.
 * @genpd: PM domain to power up.
 * @depth: nesting count for lockdep.
 *
 * Restore power to @genpd and all of its masters so that it is possible to
 * resume a device belonging to it.
 */
static int __genpd_poweron(struct generic_pm_domain *genpd, unsigned int depth)
{
        struct gpd_link *link;
        int ret = 0;

        if (genpd->status == GPD_STATE_ACTIVE
            || (genpd->prepared_count > 0 && genpd->suspend_power_off))
                return 0;

        /*
         * The list is guaranteed not to change while the loop below is being
         * executed, unless one of the masters' .power_on() callbacks fiddles
         * with it.
         */
        list_for_each_entry(link, &genpd->slave_links, slave_node) {
                struct generic_pm_domain *master = link->master;

                genpd_sd_counter_inc(master);

                mutex_lock_nested(&master->lock, depth + 1);
                ret = __genpd_poweron(master, depth + 1);
                mutex_unlock(&master->lock);

                if (ret) {
                        genpd_sd_counter_dec(master);
                        goto err;
                }
        }

        ret = genpd_power_on(genpd, true);
        if (ret)
                goto err;

        genpd->status = GPD_STATE_ACTIVE;
        return 0;

 err:
        list_for_each_entry_continue_reverse(link,
                                        &genpd->slave_links,
                                        slave_node) {
                genpd_sd_counter_dec(link->master);
                genpd_queue_power_off_work(link->master);
        }

        return ret;
}

/**
 * genpd_poweron - Restore power to a given PM domain and its masters.
 * @genpd: PM domain to power up.
 */
static int genpd_poweron(struct generic_pm_domain *genpd)
{
        int ret;

        mutex_lock(&genpd->lock);
        ret = __genpd_poweron(genpd, 0);
        mutex_unlock(&genpd->lock);
        return ret;
}


static int genpd_save_dev(struct generic_pm_domain *genpd, struct device *dev)
{
        return GENPD_DEV_CALLBACK(genpd, int, save_state, dev);
}

static int genpd_restore_dev(struct generic_pm_domain *genpd,
                        struct device *dev)
{
        return GENPD_DEV_CALLBACK(genpd, int, restore_state, dev);
}

static int genpd_dev_pm_qos_notifier(struct notifier_block *nb,
                                     unsigned long val, void *ptr)
{
        struct generic_pm_domain_data *gpd_data;
        struct device *dev;

        gpd_data = container_of(nb, struct generic_pm_domain_data, nb);
        dev = gpd_data->base.dev;

        for (;;) {
                struct generic_pm_domain *genpd;
                struct pm_domain_data *pdd;

                spin_lock_irq(&dev->power.lock);

                pdd = dev->power.subsys_data ?
                                dev->power.subsys_data->domain_data : NULL;
                if (pdd && pdd->dev) {
                        to_gpd_data(pdd)->td.constraint_changed = true;
                        genpd = dev_to_genpd(dev);
                } else {
                        genpd = ERR_PTR(-ENODATA);
                }

                spin_unlock_irq(&dev->power.lock);

                if (!IS_ERR(genpd)) {
                        mutex_lock(&genpd->lock);
                        genpd->max_off_time_changed = true;
                        mutex_unlock(&genpd->lock);
                }

                dev = dev->parent;
                if (!dev || dev->power.ignore_children)
                        break;
        }

        return NOTIFY_DONE;
}

/**
 * genpd_poweroff - Remove power from a given PM domain.
 * @genpd: PM domain to power down.
 * @is_async: PM domain is powered down from a scheduled work
 *
 * If all of the @genpd's devices have been suspended and all of its subdomains
 * have been powered down, remove power from @genpd.
 */
static int genpd_poweroff(struct generic_pm_domain *genpd, bool is_async)
{
        struct pm_domain_data *pdd;
        struct gpd_link *link;
        unsigned int not_suspended = 0;

        /*
         * Do not try to power off the domain in the following situations:
         * (1) The domain is already in the "power off" state.
         * (2) System suspend is in progress.
         */
        if (genpd->status == GPD_STATE_POWER_OFF
            || genpd->prepared_count > 0)
                return 0;

        if (atomic_read(&genpd->sd_count) > 0)
                return -EBUSY;

        list_for_each_entry(pdd, &genpd->dev_list, list_node) {
                enum pm_qos_flags_status stat;

                stat = dev_pm_qos_flags(pdd->dev,
                                        PM_QOS_FLAG_NO_POWER_OFF
                                                | PM_QOS_FLAG_REMOTE_WAKEUP);
                if (stat > PM_QOS_FLAGS_NONE)
                        return -EBUSY;

                if (!pm_runtime_suspended(pdd->dev) || pdd->dev->power.irq_safe)
                        not_suspended++;
        }

        if (not_suspended > 1 || (not_suspended == 1 && is_async))
                return -EBUSY;

        if (genpd->gov && genpd->gov->power_down_ok) {
                if (!genpd->gov->power_down_ok(&genpd->domain))
                        return -EAGAIN;
        }

        if (genpd->power_off) {
                int ret;

                if (atomic_read(&genpd->sd_count) > 0)
                        return -EBUSY;

                /*
                 * If sd_count > 0 at this point, one of the subdomains hasn't
                 * managed to call genpd_poweron() for the master yet after
                 * incrementing it.  In that case genpd_poweron() will wait
                 * for us to drop the lock, so we can call .power_off() and let
                 * the genpd_poweron() restore power for us (this shouldn't
                 * happen very often).
                 */
                ret = genpd_power_off(genpd, true);
                if (ret)
                        return ret;
        }

        genpd->status = GPD_STATE_POWER_OFF;

        list_for_each_entry(link, &genpd->slave_links, slave_node) {
                genpd_sd_counter_dec(link->master);
                genpd_queue_power_off_work(link->master);
        }

        return 0;
}

/**
 * genpd_power_off_work_fn - Power off PM domain whose subdomain count is 0.
 * @work: Work structure used for scheduling the execution of this function.
 */
static void genpd_power_off_work_fn(struct work_struct *work)
{
        struct generic_pm_domain *genpd;

        genpd = container_of(work, struct generic_pm_domain, power_off_work);

        mutex_lock(&genpd->lock);
        genpd_poweroff(genpd, true);
        mutex_unlock(&genpd->lock);
}

/**
 * pm_genpd_runtime_suspend - Suspend a device belonging to I/O PM domain.
 * @dev: Device to suspend.
 *
 * Carry out a runtime suspend of a device under the assumption that its
 * pm_domain field points to the domain member of an object of type
 * struct generic_pm_domain representing a PM domain consisting of I/O devices.
 */
static int pm_genpd_runtime_suspend(struct device *dev)
{
        struct generic_pm_domain *genpd;
        bool (*stop_ok)(struct device *__dev);
        struct gpd_timing_data *td = &dev_gpd_data(dev)->td;
        bool runtime_pm = pm_runtime_enabled(dev);
        ktime_t time_start;
        s64 elapsed_ns;
        int ret;

        dev_dbg(dev, "%s()\n", __func__);

        genpd = dev_to_genpd(dev);
        if (IS_ERR(genpd))
                return -EINVAL;

        /*
         * A runtime PM centric subsystem/driver may re-use the runtime PM
         * callbacks for other purposes than runtime PM. In those scenarios
         * runtime PM is disabled. Under these circumstances, we shall skip
         * validating/measuring the PM QoS latency.
         */
        stop_ok = genpd->gov ? genpd->gov->stop_ok : NULL;
        if (runtime_pm && stop_ok && !stop_ok(dev))
                return -EBUSY;

        /* Measure suspend latency. */
        if (runtime_pm)
                time_start = ktime_get();

        ret = genpd_save_dev(genpd, dev);
        if (ret)
                return ret;

        ret = genpd_stop_dev(genpd, dev);
        if (ret) {
                genpd_restore_dev(genpd, dev);
                return ret;
        }

        /* Update suspend latency value if the measured time exceeds it. */
        if (runtime_pm) {
                elapsed_ns = ktime_to_ns(ktime_sub(ktime_get(), time_start));
                if (elapsed_ns > td->suspend_latency_ns) {
                        td->suspend_latency_ns = elapsed_ns;
                        dev_dbg(dev, "suspend latency exceeded, %lld ns\n",
                                elapsed_ns);
                        genpd->max_off_time_changed = true;
                        td->constraint_changed = true;
                }
        }

        /*
         * If power.irq_safe is set, this routine will be run with interrupts
         * off, so it can't use mutexes.
         */
        if (dev->power.irq_safe)
                return 0;

        mutex_lock(&genpd->lock);
        genpd_poweroff(genpd, false);
        mutex_unlock(&genpd->lock);

        return 0;
}

/**
 * pm_genpd_runtime_resume - Resume a device belonging to I/O PM domain.
 * @dev: Device to resume.
 *
 * Carry out a runtime resume of a device under the assumption that its
 * pm_domain field points to the domain member of an object of type
 * struct generic_pm_domain representing a PM domain consisting of I/O devices.
 */
static int pm_genpd_runtime_resume(struct device *dev)
{
        struct generic_pm_domain *genpd;
        struct gpd_timing_data *td = &dev_gpd_data(dev)->td;
        bool runtime_pm = pm_runtime_enabled(dev);
        ktime_t time_start;
        s64 elapsed_ns;
        int ret;
        bool timed = true;

        dev_dbg(dev, "%s()\n", __func__);

        genpd = dev_to_genpd(dev);
        if (IS_ERR(genpd))
                return -EINVAL;

        /* If power.irq_safe, the PM domain is never powered off. */
        if (dev->power.irq_safe) {
                timed = false;
                goto out;
        }

        mutex_lock(&genpd->lock);
        ret = __genpd_poweron(genpd, 0);
        mutex_unlock(&genpd->lock);

        if (ret)
                return ret;

 out:
        /* Measure resume latency. */
        if (timed && runtime_pm)
                time_start = ktime_get();

        genpd_start_dev(genpd, dev);
        genpd_restore_dev(genpd, dev);

        /* Update resume latency value if the measured time exceeds it. */
        if (timed && runtime_pm) {
                elapsed_ns = ktime_to_ns(ktime_sub(ktime_get(), time_start));
                if (elapsed_ns > td->resume_latency_ns) {
                        td->resume_latency_ns = elapsed_ns;
                        dev_dbg(dev, "resume latency exceeded, %lld ns\n",
                                elapsed_ns);
                        genpd->max_off_time_changed = true;
                        td->constraint_changed = true;
                }
        }

        return 0;
}

static bool pd_ignore_unused;
static int __init pd_ignore_unused_setup(char *__unused)
{
        pd_ignore_unused = true;
        return 1;
}
__setup("pd_ignore_unused", pd_ignore_unused_setup);

/**
 * genpd_poweroff_unused - Power off all PM domains with no devices in use.
 */
static int __init genpd_poweroff_unused(void)
{
        struct generic_pm_domain *genpd;

        if (pd_ignore_unused) {
                pr_warn("genpd: Not disabling unused power domains\n");
                return 0;
        }

        mutex_lock(&gpd_list_lock);

        list_for_each_entry(genpd, &gpd_list, gpd_list_node)
                genpd_queue_power_off_work(genpd);

        mutex_unlock(&gpd_list_lock);

        return 0;
}
late_initcall(genpd_poweroff_unused);

#ifdef CONFIG_PM_SLEEP

/**
 * pm_genpd_present - Check if the given PM domain has been initialized.
 * @genpd: PM domain to check.
 */
static bool pm_genpd_present(const struct generic_pm_domain *genpd)
{
        const struct generic_pm_domain *gpd;

        if (IS_ERR_OR_NULL(genpd))
                return false;

        list_for_each_entry(gpd, &gpd_list, gpd_list_node)
                if (gpd == genpd)
                        return true;

        return false;
}

static bool genpd_dev_active_wakeup(struct generic_pm_domain *genpd,
                                    struct device *dev)
{
        return GENPD_DEV_CALLBACK(genpd, bool, active_wakeup, dev);
}

/**
 * pm_genpd_sync_poweroff - Synchronously power off a PM domain and its masters.
 * @genpd: PM domain to power off, if possible.
 * @timed: True if latency measurements are allowed.
 *
 * Check if the given PM domain can be powered off (during system suspend or
 * hibernation) and do that if so.  Also, in that case propagate to its masters.
 *
 * This function is only called in "noirq" and "syscore" stages of system power
 * transitions, so it need not acquire locks (all of the "noirq" callbacks are
 * executed sequentially, so it is guaranteed that it will never run twice in
 * parallel).
 */
static void pm_genpd_sync_poweroff(struct generic_pm_domain *genpd,
                                   bool timed)
{
        struct gpd_link *link;

        if (genpd->status == GPD_STATE_POWER_OFF)
                return;

        if (genpd->suspended_count != genpd->device_count
            || atomic_read(&genpd->sd_count) > 0)
                return;

        genpd_power_off(genpd, timed);

        genpd->status = GPD_STATE_POWER_OFF;

        list_for_each_entry(link, &genpd->slave_links, slave_node) {
                genpd_sd_counter_dec(link->master);
                pm_genpd_sync_poweroff(link->master, timed);
        }
}

/**
 * pm_genpd_sync_poweron - Synchronously power on a PM domain and its masters.
 * @genpd: PM domain to power on.
 * @timed: True if latency measurements are allowed.
 *
 * This function is only called in "noirq" and "syscore" stages of system power
 * transitions, so it need not acquire locks (all of the "noirq" callbacks are
 * executed sequentially, so it is guaranteed that it will never run twice in
 * parallel).
 */
static void pm_genpd_sync_poweron(struct generic_pm_domain *genpd,
                                  bool timed)
{
        struct gpd_link *link;

        if (genpd->status == GPD_STATE_ACTIVE)
                return;

        list_for_each_entry(link, &genpd->slave_links, slave_node) {
                pm_genpd_sync_poweron(link->master, timed);
                genpd_sd_counter_inc(link->master);
        }

        genpd_power_on(genpd, timed);

        genpd->status = GPD_STATE_ACTIVE;
}

/**
 * resume_needed - Check whether to resume a device before system suspend.
 * @dev: Device to check.
 * @genpd: PM domain the device belongs to.
 *
 * There are two cases in which a device that can wake up the system from sleep
 * states should be resumed by pm_genpd_prepare(): (1) if the device is enabled
 * to wake up the system and it has to remain active for this purpose while the
 * system is in the sleep state and (2) if the device is not enabled to wake up
 * the system from sleep states and it generally doesn't generate wakeup signals
 * by itself (those signals are generated on its behalf by other parts of the
 * system).  In the latter case it may be necessary to reconfigure the device's
 * wakeup settings during system suspend, because it may have been set up to
 * signal remote wakeup from the system's working state as needed by runtime PM.
 * Return 'true' in either of the above cases.
 */
static bool resume_needed(struct device *dev, struct generic_pm_domain *genpd)
{
        bool active_wakeup;

        if (!device_can_wakeup(dev))
                return false;

        active_wakeup = genpd_dev_active_wakeup(genpd, dev);
        return device_may_wakeup(dev) ? active_wakeup : !active_wakeup;
}

/**
 * pm_genpd_prepare - Start power transition of a device in a PM domain.
 * @dev: Device to start the transition of.
 *
 * Start a power transition of a device (during a system-wide power transition)
 * under the assumption that its pm_domain field points to the domain member of
 * an object of type struct generic_pm_domain representing a PM domain
 * consisting of I/O devices.
 */
static int pm_genpd_prepare(struct device *dev)
{
        struct generic_pm_domain *genpd;
        int ret;

        dev_dbg(dev, "%s()\n", __func__);

        genpd = dev_to_genpd(dev);
        if (IS_ERR(genpd))
                return -EINVAL;

        /*
         * If a wakeup request is pending for the device, it should be woken up
         * at this point and a system wakeup event should be reported if it's
         * set up to wake up the system from sleep states.
         */
        pm_runtime_get_noresume(dev);
        if (pm_runtime_barrier(dev) && device_may_wakeup(dev))
                pm_wakeup_event(dev, 0);

        if (pm_wakeup_pending()) {
                pm_runtime_put(dev);
                return -EBUSY;
        }

        if (resume_needed(dev, genpd))
                pm_runtime_resume(dev);

        mutex_lock(&genpd->lock);

        if (genpd->prepared_count++ == 0) {
                genpd->suspended_count = 0;
                genpd->suspend_power_off = genpd->status == GPD_STATE_POWER_OFF;
        }

        mutex_unlock(&genpd->lock);

        if (genpd->suspend_power_off) {
                pm_runtime_put_noidle(dev);
                return 0;
        }

        /*
         * The PM domain must be in the GPD_STATE_ACTIVE state at this point,
         * so genpd_poweron() will return immediately, but if the device
         * is suspended (e.g. it's been stopped by genpd_stop_dev()), we need
         * to make it operational.
         */
        pm_runtime_resume(dev);
        __pm_runtime_disable(dev, false);

        ret = pm_generic_prepare(dev);
        if (ret) {
                mutex_lock(&genpd->lock);

                if (--genpd->prepared_count == 0)
                        genpd->suspend_power_off = false;

                mutex_unlock(&genpd->lock);
                pm_runtime_enable(dev);
        }

        pm_runtime_put(dev);
        return ret;
}

/**
 * pm_genpd_suspend - Suspend a device belonging to an I/O PM domain.
 * @dev: Device to suspend.
 *
 * Suspend a device under the assumption that its pm_domain field points to the
 * domain member of an object of type struct generic_pm_domain representing
 * a PM domain consisting of I/O devices.
 */
static int pm_genpd_suspend(struct device *dev)
{
        struct generic_pm_domain *genpd;

        dev_dbg(dev, "%s()\n", __func__);

        genpd = dev_to_genpd(dev);
        if (IS_ERR(genpd))
                return -EINVAL;

        return genpd->suspend_power_off ? 0 : pm_generic_suspend(dev);
}

/**
 * pm_genpd_suspend_late - Late suspend of a device from an I/O PM domain.
 * @dev: Device to suspend.
 *
 * Carry out a late suspend of a device under the assumption that its
 * pm_domain field points to the domain member of an object of type
 * struct generic_pm_domain representing a PM domain consisting of I/O devices.
 */
static int pm_genpd_suspend_late(struct device *dev)
{
        struct generic_pm_domain *genpd;

        dev_dbg(dev, "%s()\n", __func__);

        genpd = dev_to_genpd(dev);
        if (IS_ERR(genpd))
                return -EINVAL;

        return genpd->suspend_power_off ? 0 : pm_generic_suspend_late(dev);
}

/**
 * pm_genpd_suspend_noirq - Completion of suspend of device in an I/O PM domain.
 * @dev: Device to suspend.
 *
 * Stop the device and remove power from the domain if all devices in it have
 * been stopped.
 */
static int pm_genpd_suspend_noirq(struct device *dev)
{
        struct generic_pm_domain *genpd;

        dev_dbg(dev, "%s()\n", __func__);

        genpd = dev_to_genpd(dev);
        if (IS_ERR(genpd))
                return -EINVAL;

        if (genpd->suspend_power_off
            || (dev->power.wakeup_path && genpd_dev_active_wakeup(genpd, dev)))
                return 0;

        genpd_stop_dev(genpd, dev);

        /*
         * Since all of the "noirq" callbacks are executed sequentially, it is
         * guaranteed that this function will never run twice in parallel for
         * the same PM domain, so it is not necessary to use locking here.
         */
        genpd->suspended_count++;
        pm_genpd_sync_poweroff(genpd, true);

        return 0;
}

/**
 * pm_genpd_resume_noirq - Start of resume of device in an I/O PM domain.
 * @dev: Device to resume.
 *
 * Restore power to the device's PM domain, if necessary, and start the device.
 */
static int pm_genpd_resume_noirq(struct device *dev)
{
        struct generic_pm_domain *genpd;

        dev_dbg(dev, "%s()\n", __func__);

        genpd = dev_to_genpd(dev);
        if (IS_ERR(genpd))
                return -EINVAL;

        if (genpd->suspend_power_off
            || (dev->power.wakeup_path && genpd_dev_active_wakeup(genpd, dev)))
                return 0;

        /*
         * Since all of the "noirq" callbacks are executed sequentially, it is
         * guaranteed that this function will never run twice in parallel for
         * the same PM domain, so it is not necessary to use locking here.
         */
        pm_genpd_sync_poweron(genpd, true);
        genpd->suspended_count--;

        return genpd_start_dev(genpd, dev);
}

/**
 * pm_genpd_resume_early - Early resume of a device in an I/O PM domain.
 * @dev: Device to resume.
 *
 * Carry out an early resume of a device under the assumption that its
 * pm_domain field points to the domain member of an object of type
 * struct generic_pm_domain representing a power domain consisting of I/O
 * devices.
 */
static int pm_genpd_resume_early(struct device *dev)
{
        struct generic_pm_domain *genpd;

        dev_dbg(dev, "%s()\n", __func__);

        genpd = dev_to_genpd(dev);
        if (IS_ERR(genpd))
                return -EINVAL;

        return genpd->suspend_power_off ? 0 : pm_generic_resume_early(dev);
}

/**
 * pm_genpd_resume - Resume of device in an I/O PM domain.
 * @dev: Device to resume.
 *
 * Resume a device under the assumption that its pm_domain field points to the
 * domain member of an object of type struct generic_pm_domain representing
 * a power domain consisting of I/O devices.
 */
static int pm_genpd_resume(struct device *dev)
{
        struct generic_pm_domain *genpd;

        dev_dbg(dev, "%s()\n", __func__);

        genpd = dev_to_genpd(dev);
        if (IS_ERR(genpd))
                return -EINVAL;

        return genpd->suspend_power_off ? 0 : pm_generic_resume(dev);
}

/**
 * pm_genpd_freeze - Freezing a device in an I/O PM domain.
 * @dev: Device to freeze.
 *
 * Freeze a device under the assumption that its pm_domain field points to the
 * domain member of an object of type struct generic_pm_domain representing
 * a power domain consisting of I/O devices.
 */
static int pm_genpd_freeze(struct device *dev)
{
        struct generic_pm_domain *genpd;

        dev_dbg(dev, "%s()\n", __func__);

        genpd = dev_to_genpd(dev);
        if (IS_ERR(genpd))
                return -EINVAL;

        return genpd->suspend_power_off ? 0 : pm_generic_freeze(dev);
}

/**
 * pm_genpd_freeze_late - Late freeze of a device in an I/O PM domain.
 * @dev: Device to freeze.
 *
 * Carry out a late freeze of a device under the assumption that its
 * pm_domain field points to the domain member of an object of type
 * struct generic_pm_domain representing a power domain consisting of I/O
 * devices.
 */
static int pm_genpd_freeze_late(struct device *dev)
{
        struct generic_pm_domain *genpd;

        dev_dbg(dev, "%s()\n", __func__);

        genpd = dev_to_genpd(dev);
        if (IS_ERR(genpd))
                return -EINVAL;

        return genpd->suspend_power_off ? 0 : pm_generic_freeze_late(dev);
}

/**
 * pm_genpd_freeze_noirq - Completion of freezing a device in an I/O PM domain.
 * @dev: Device to freeze.
 *
 * Carry out a late freeze of a device under the assumption that its
 * pm_domain field points to the domain member of an object of type
 * struct generic_pm_domain representing a power domain consisting of I/O
 * devices.
 */
static int pm_genpd_freeze_noirq(struct device *dev)
{
        struct generic_pm_domain *genpd;

        dev_dbg(dev, "%s()\n", __func__);

        genpd = dev_to_genpd(dev);
        if (IS_ERR(genpd))
                return -EINVAL;

        return genpd->suspend_power_off ? 0 : genpd_stop_dev(genpd, dev);
}

/**
 * pm_genpd_thaw_noirq - Early thaw of device in an I/O PM domain.
 * @dev: Device to thaw.
 *
 * Start the device, unless power has been removed from the domain already
 * before the system transition.
 */
static int pm_genpd_thaw_noirq(struct device *dev)
{
        struct generic_pm_domain *genpd;

        dev_dbg(dev, "%s()\n", __func__);

        genpd = dev_to_genpd(dev);
        if (IS_ERR(genpd))
                return -EINVAL;

        return genpd->suspend_power_off ?
                0 : genpd_start_dev(genpd, dev);
}

/**
 * pm_genpd_thaw_early - Early thaw of device in an I/O PM domain.
 * @dev: Device to thaw.
 *
 * Carry out an early thaw of a device under the assumption that its
 * pm_domain field points to the domain member of an object of type
 * struct generic_pm_domain representing a power domain consisting of I/O
 * devices.
 */
static int pm_genpd_thaw_early(struct device *dev)
{
        struct generic_pm_domain *genpd;

        dev_dbg(dev, "%s()\n", __func__);

        genpd = dev_to_genpd(dev);
        if (IS_ERR(genpd))
                return -EINVAL;

        return genpd->suspend_power_off ? 0 : pm_generic_thaw_early(dev);
}

/**
 * pm_genpd_thaw - Thaw a device belonging to an I/O power domain.
 * @dev: Device to thaw.
 *
 * Thaw a device under the assumption that its pm_domain field points to the
 * domain member of an object of type struct generic_pm_domain representing
 * a power domain consisting of I/O devices.
 */
static int pm_genpd_thaw(struct device *dev)
{
        struct generic_pm_domain *genpd;

        dev_dbg(dev, "%s()\n", __func__);

        genpd = dev_to_genpd(dev);
        if (IS_ERR(genpd))
                return -EINVAL;

        return genpd->suspend_power_off ? 0 : pm_generic_thaw(dev);
}

/**
 * pm_genpd_restore_noirq - Start of restore of device in an I/O PM domain.
 * @dev: Device to resume.
 *
 * Make sure the domain will be in the same power state as before the
 * hibernation the system is resuming from and start the device if necessary.
 */
static int pm_genpd_restore_noirq(struct device *dev)
{
        struct generic_pm_domain *genpd;

        dev_dbg(dev, "%s()\n", __func__);

        genpd = dev_to_genpd(dev);
        if (IS_ERR(genpd))
                return -EINVAL;

        /*
         * Since all of the "noirq" callbacks are executed sequentially, it is
         * guaranteed that this function will never run twice in parallel for
         * the same PM domain, so it is not necessary to use locking here.
         *
         * At this point suspended_count == 0 means we are being run for the
         * first time for the given domain in the present cycle.
         */
        if (genpd->suspended_count++ == 0) {
                /*
                 * The boot kernel might put the domain into arbitrary state,
                 * so make it appear as powered off to pm_genpd_sync_poweron(),
                 * so that it tries to power it on in case it was really off.
                 */
                genpd->status = GPD_STATE_POWER_OFF;
                if (genpd->suspend_power_off) {
                        /*
                         * If the domain was off before the hibernation, make
                         * sure it will be off going forward.
                         */
                        genpd_power_off(genpd, true);

                        return 0;
                }
        }

        if (genpd->suspend_power_off)
                return 0;

        pm_genpd_sync_poweron(genpd, true);

        return genpd_start_dev(genpd, dev);
}

/**
 * pm_genpd_complete - Complete power transition of a device in a power domain.
 * @dev: Device to complete the transition of.
 *
 * Complete a power transition of a device (during a system-wide power
 * transition) under the assumption that its pm_domain field points to the
 * domain member of an object of type struct generic_pm_domain representing
 * a power domain consisting of I/O devices.
 */
static void pm_genpd_complete(struct device *dev)
{
        struct generic_pm_domain *genpd;
        bool run_complete;

        dev_dbg(dev, "%s()\n", __func__);

        genpd = dev_to_genpd(dev);
        if (IS_ERR(genpd))
                return;

        mutex_lock(&genpd->lock);

        run_complete = !genpd->suspend_power_off;
        if (--genpd->prepared_count == 0)
                genpd->suspend_power_off = false;

        mutex_unlock(&genpd->lock);

        if (run_complete) {
                pm_generic_complete(dev);
                pm_runtime_set_active(dev);
                pm_runtime_enable(dev);
                pm_request_idle(dev);
        }
}

/**
 * genpd_syscore_switch - Switch power during system core suspend or resume.
 * @dev: Device that normally is marked as "always on" to switch power for.
 *
 * This routine may only be called during the system core (syscore) suspend or
 * resume phase for devices whose "always on" flags are set.
 */
static void genpd_syscore_switch(struct device *dev, bool suspend)
{
        struct generic_pm_domain *genpd;

        genpd = dev_to_genpd(dev);
        if (!pm_genpd_present(genpd))
                return;

        if (suspend) {
                genpd->suspended_count++;
                pm_genpd_sync_poweroff(genpd, false);
        } else {
                pm_genpd_sync_poweron(genpd, false);
                genpd->suspended_count--;
        }
}

void pm_genpd_syscore_poweroff(struct device *dev)
{
        genpd_syscore_switch(dev, true);
}
EXPORT_SYMBOL_GPL(pm_genpd_syscore_poweroff);

void pm_genpd_syscore_poweron(struct device *dev)
{
        genpd_syscore_switch(dev, false);
}
EXPORT_SYMBOL_GPL(pm_genpd_syscore_poweron);

#else /* !CONFIG_PM_SLEEP */

#define pm_genpd_prepare                NULL
#define pm_genpd_suspend                NULL
#define pm_genpd_suspend_late           NULL
#define pm_genpd_suspend_noirq          NULL
#define pm_genpd_resume_early           NULL
#define pm_genpd_resume_noirq           NULL
#define pm_genpd_resume                 NULL
#define pm_genpd_freeze                 NULL
#define pm_genpd_freeze_late            NULL
#define pm_genpd_freeze_noirq           NULL
#define pm_genpd_thaw_early             NULL
#define pm_genpd_thaw_noirq             NULL
#define pm_genpd_thaw                   NULL
#define pm_genpd_restore_noirq          NULL
#define pm_genpd_complete               NULL

#endif /* CONFIG_PM_SLEEP */

static struct generic_pm_domain_data *genpd_alloc_dev_data(struct device *dev,
                                        struct generic_pm_domain *genpd,
                                        struct gpd_timing_data *td)
{
        struct generic_pm_domain_data *gpd_data;
        int ret;

        ret = dev_pm_get_subsys_data(dev);
        if (ret)
                return ERR_PTR(ret);

        gpd_data = kzalloc(sizeof(*gpd_data), GFP_KERNEL);
        if (!gpd_data) {
                ret = -ENOMEM;
                goto err_put;
        }

        if (td)
                gpd_data->td = *td;

        gpd_data->base.dev = dev;
        gpd_data->td.constraint_changed = true;
        gpd_data->td.effective_constraint_ns = -1;
        gpd_data->nb.notifier_call = genpd_dev_pm_qos_notifier;

        spin_lock_irq(&dev->power.lock);

        if (dev->power.subsys_data->domain_data) {
                ret = -EINVAL;
                goto err_free;
        }

        dev->power.subsys_data->domain_data = &gpd_data->base;

        spin_unlock_irq(&dev->power.lock);

        dev_pm_domain_set(dev, &genpd->domain);

        return gpd_data;

 err_free:
        spin_unlock_irq(&dev->power.lock);
        kfree(gpd_data);
 err_put:
        dev_pm_put_subsys_data(dev);
        return ERR_PTR(ret);
}

static void genpd_free_dev_data(struct device *dev,
                                struct generic_pm_domain_data *gpd_data)
{
        dev_pm_domain_set(dev, NULL);

        spin_lock_irq(&dev->power.lock);

        dev->power.subsys_data->domain_data = NULL;

        spin_unlock_irq(&dev->power.lock);

        kfree(gpd_data);
        dev_pm_put_subsys_data(dev);
}

/**
 * __pm_genpd_add_device - Add a device to an I/O PM domain.
 * @genpd: PM domain to add the device to.
 * @dev: Device to be added.
 * @td: Set of PM QoS timing parameters to attach to the device.
 */
int __pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
                          struct gpd_timing_data *td)
{
        struct generic_pm_domain_data *gpd_data;
        int ret = 0;

        dev_dbg(dev, "%s()\n", __func__);

        if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(dev))
                return -EINVAL;

        gpd_data = genpd_alloc_dev_data(dev, genpd, td);
        if (IS_ERR(gpd_data))
                return PTR_ERR(gpd_data);

        mutex_lock(&genpd->lock);

        if (genpd->prepared_count > 0) {
                ret = -EAGAIN;
                goto out;
        }

        ret = genpd->attach_dev ? genpd->attach_dev(genpd, dev) : 0;
        if (ret)
                goto out;

        genpd->device_count++;
        genpd->max_off_time_changed = true;

        list_add_tail(&gpd_data->base.list_node, &genpd->dev_list);

 out:
        mutex_unlock(&genpd->lock);

        if (ret)
                genpd_free_dev_data(dev, gpd_data);
        else
                dev_pm_qos_add_notifier(dev, &gpd_data->nb);

        return ret;
}
EXPORT_SYMBOL_GPL(__pm_genpd_add_device);

/**
 * pm_genpd_remove_device - Remove a device from an I/O PM domain.
 * @genpd: PM domain to remove the device from.
 * @dev: Device to be removed.
 */
int pm_genpd_remove_device(struct generic_pm_domain *genpd,
                           struct device *dev)
{
        struct generic_pm_domain_data *gpd_data;
        struct pm_domain_data *pdd;
        int ret = 0;

        dev_dbg(dev, "%s()\n", __func__);

        if (!genpd || genpd != pm_genpd_lookup_dev(dev))
                return -EINVAL;

        /* The above validation also means we have existing domain_data. */
        pdd = dev->power.subsys_data->domain_data;
        gpd_data = to_gpd_data(pdd);
        dev_pm_qos_remove_notifier(dev, &gpd_data->nb);

        mutex_lock(&genpd->lock);

        if (genpd->prepared_count > 0) {
                ret = -EAGAIN;
                goto out;
        }

        genpd->device_count--;
        genpd->max_off_time_changed = true;

        if (genpd->detach_dev)
                genpd->detach_dev(genpd, dev);

        list_del_init(&pdd->list_node);

        mutex_unlock(&genpd->lock);

        genpd_free_dev_data(dev, gpd_data);

        return 0;

 out:
        mutex_unlock(&genpd->lock);
        dev_pm_qos_add_notifier(dev, &gpd_data->nb);

        return ret;
}
EXPORT_SYMBOL_GPL(pm_genpd_remove_device);

/**
 * pm_genpd_add_subdomain - Add a subdomain to an I/O PM domain.
 * @genpd: Master PM domain to add the subdomain to.
 * @subdomain: Subdomain to be added.
 */
int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
                           struct generic_pm_domain *subdomain)
{
        struct gpd_link *link, *itr;
        int ret = 0;

        if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(subdomain)
            || genpd == subdomain)
                return -EINVAL;

        link = kzalloc(sizeof(*link), GFP_KERNEL);
        if (!link)
                return -ENOMEM;

        mutex_lock(&subdomain->lock);
        mutex_lock_nested(&genpd->lock, SINGLE_DEPTH_NESTING);

        if (genpd->status == GPD_STATE_POWER_OFF
            &&  subdomain->status != GPD_STATE_POWER_OFF) {
                ret = -EINVAL;
                goto out;
        }

        list_for_each_entry(itr, &genpd->master_links, master_node) {
                if (itr->slave == subdomain && itr->master == genpd) {
                        ret = -EINVAL;
                        goto out;
                }
        }

        link->master = genpd;
        list_add_tail(&link->master_node, &genpd->master_links);
        link->slave = subdomain;
        list_add_tail(&link->slave_node, &subdomain->slave_links);
        if (subdomain->status != GPD_STATE_POWER_OFF)
                genpd_sd_counter_inc(genpd);

 out:
        mutex_unlock(&genpd->lock);
        mutex_unlock(&subdomain->lock);
        if (ret)
                kfree(link);
        return ret;
}
EXPORT_SYMBOL_GPL(pm_genpd_add_subdomain);

/**
 * pm_genpd_remove_subdomain - Remove a subdomain from an I/O PM domain.
 * @genpd: Master PM domain to remove the subdomain from.
 * @subdomain: Subdomain to be removed.
 */
int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
                              struct generic_pm_domain *subdomain)
{
        struct gpd_link *link;
        int ret = -EINVAL;

        if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(subdomain))
                return -EINVAL;

        mutex_lock(&subdomain->lock);
        mutex_lock_nested(&genpd->lock, SINGLE_DEPTH_NESTING);

        if (!list_empty(&subdomain->slave_links) || subdomain->device_count) {
                pr_warn("%s: unable to remove subdomain %s\n", genpd->name,
                        subdomain->name);
                ret = -EBUSY;
                goto out;
        }

        list_for_each_entry(link, &genpd->master_links, master_node) {
                if (link->slave != subdomain)
                        continue;

                list_del(&link->master_node);
                list_del(&link->slave_node);
                kfree(link);
                if (subdomain->status != GPD_STATE_POWER_OFF)
                        genpd_sd_counter_dec(genpd);

                ret = 0;
                break;
        }

out:
        mutex_unlock(&genpd->lock);
        mutex_unlock(&subdomain->lock);

        return ret;
}
EXPORT_SYMBOL_GPL(pm_genpd_remove_subdomain);

/* Default device callbacks for generic PM domains. */

/**
 * pm_genpd_default_save_state - Default "save device state" for PM domains.
 * @dev: Device to handle.
 */
static int pm_genpd_default_save_state(struct device *dev)
{
        int (*cb)(struct device *__dev);

        if (dev->type && dev->type->pm)
                cb = dev->type->pm->runtime_suspend;
        else if (dev->class && dev->class->pm)
                cb = dev->class->pm->runtime_suspend;
        else if (dev->bus && dev->bus->pm)
                cb = dev->bus->pm->runtime_suspend;
        else
                cb = NULL;

        if (!cb && dev->driver && dev->driver->pm)
                cb = dev->driver->pm->runtime_suspend;

        return cb ? cb(dev) : 0;
}

/**
 * pm_genpd_default_restore_state - Default PM domains "restore device state".
 * @dev: Device to handle.
 */
static int pm_genpd_default_restore_state(struct device *dev)
{
        int (*cb)(struct device *__dev);

        if (dev->type && dev->type->pm)
                cb = dev->type->pm->runtime_resume;
        else if (dev->class && dev->class->pm)
                cb = dev->class->pm->runtime_resume;
        else if (dev->bus && dev->bus->pm)
                cb = dev->bus->pm->runtime_resume;
        else
                cb = NULL;

        if (!cb && dev->driver && dev->driver->pm)
                cb = dev->driver->pm->runtime_resume;

        return cb ? cb(dev) : 0;
}

/**
 * pm_genpd_init - Initialize a generic I/O PM domain object.
 * @genpd: PM domain object to initialize.
 * @gov: PM domain governor to associate with the domain (may be NULL).
 * @is_off: Initial value of the domain's power_is_off field.
 */
void pm_genpd_init(struct generic_pm_domain *genpd,
                   struct dev_power_governor *gov, bool is_off)
{
        if (IS_ERR_OR_NULL(genpd))
                return;

        INIT_LIST_HEAD(&genpd->master_links);
        INIT_LIST_HEAD(&genpd->slave_links);
        INIT_LIST_HEAD(&genpd->dev_list);
        mutex_init(&genpd->lock);
        genpd->gov = gov;
        INIT_WORK(&genpd->power_off_work, genpd_power_off_work_fn);
        atomic_set(&genpd->sd_count, 0);
        genpd->status = is_off ? GPD_STATE_POWER_OFF : GPD_STATE_ACTIVE;
        genpd->device_count = 0;
        genpd->max_off_time_ns = -1;
        genpd->max_off_time_changed = true;
        genpd->domain.ops.runtime_suspend = pm_genpd_runtime_suspend;
        genpd->domain.ops.runtime_resume = pm_genpd_runtime_resume;
        genpd->domain.ops.prepare = pm_genpd_prepare;
        genpd->domain.ops.suspend = pm_genpd_suspend;
        genpd->domain.ops.suspend_late = pm_genpd_suspend_late;
        genpd->domain.ops.suspend_noirq = pm_genpd_suspend_noirq;
        genpd->domain.ops.resume_noirq = pm_genpd_resume_noirq;
        genpd->domain.ops.resume_early = pm_genpd_resume_early;
        genpd->domain.ops.resume = pm_genpd_resume;
        genpd->domain.ops.freeze = pm_genpd_freeze;
        genpd->domain.ops.freeze_late = pm_genpd_freeze_late;
        genpd->domain.ops.freeze_noirq = pm_genpd_freeze_noirq;
        genpd->domain.ops.thaw_noirq = pm_genpd_thaw_noirq;
        genpd->domain.ops.thaw_early = pm_genpd_thaw_early;
        genpd->domain.ops.thaw = pm_genpd_thaw;
        genpd->domain.ops.poweroff = pm_genpd_suspend;
        genpd->domain.ops.poweroff_late = pm_genpd_suspend_late;
        genpd->domain.ops.poweroff_noirq = pm_genpd_suspend_noirq;
        genpd->domain.ops.restore_noirq = pm_genpd_restore_noirq;
        genpd->domain.ops.restore_early = pm_genpd_resume_early;
        genpd->domain.ops.restore = pm_genpd_resume;
        genpd->domain.ops.complete = pm_genpd_complete;
        genpd->dev_ops.save_state = pm_genpd_default_save_state;
        genpd->dev_ops.restore_state = pm_genpd_default_restore_state;

        if (genpd->flags & GENPD_FLAG_PM_CLK) {
                genpd->dev_ops.stop = pm_clk_suspend;
                genpd->dev_ops.start = pm_clk_resume;
        }

        mutex_lock(&gpd_list_lock);
        list_add(&genpd->gpd_list_node, &gpd_list);
        mutex_unlock(&gpd_list_lock);
}
EXPORT_SYMBOL_GPL(pm_genpd_init);

#ifdef CONFIG_PM_GENERIC_DOMAINS_OF
/*
 * Device Tree based PM domain providers.
 *
 * The code below implements generic device tree based PM domain providers that
 * bind device tree nodes with generic PM domains registered in the system.
 *
 * Any driver that registers generic PM domains and needs to support binding of
 * devices to these domains is supposed to register a PM domain provider, which
 * maps a PM domain specifier retrieved from the device tree to a PM domain.
 *
 * Two simple mapping functions have been provided for convenience:
 *  - __of_genpd_xlate_simple() for 1:1 device tree node to PM domain mapping.
 *  - __of_genpd_xlate_onecell() for mapping of multiple PM domains per node by
 *    index.
 */

/**
 * struct of_genpd_provider - PM domain provider registration structure
 * @link: Entry in global list of PM domain providers
 * @node: Pointer to device tree node of PM domain provider
 * @xlate: Provider-specific xlate callback mapping a set of specifier cells
 *         into a PM domain.
 * @data: context pointer to be passed into @xlate callback
 */
struct of_genpd_provider {
        struct list_head link;
        struct device_node *node;
        genpd_xlate_t xlate;
        void *data;
};

/* List of registered PM domain providers. */
static LIST_HEAD(of_genpd_providers);
/* Mutex to protect the list above. */
static DEFINE_MUTEX(of_genpd_mutex);

/**
 * __of_genpd_xlate_simple() - Xlate function for direct node-domain mapping
 * @genpdspec: OF phandle args to map into a PM domain
 * @data: xlate function private data - pointer to struct generic_pm_domain
 *
 * This is a generic xlate function that can be used to model PM domains that
 * have their own device tree nodes. The private data of xlate function needs
 * to be a valid pointer to struct generic_pm_domain.
 */
struct generic_pm_domain *__of_genpd_xlate_simple(
                                        struct of_phandle_args *genpdspec,
                                        void *data)
{
        if (genpdspec->args_count != 0)
                return ERR_PTR(-EINVAL);
        return data;
}
EXPORT_SYMBOL_GPL(__of_genpd_xlate_simple);

/**
 * __of_genpd_xlate_onecell() - Xlate function using a single index.
 * @genpdspec: OF phandle args to map into a PM domain
 * @data: xlate function private data - pointer to struct genpd_onecell_data
 *
 * This is a generic xlate function that can be used to model simple PM domain
 * controllers that have one device tree node and provide multiple PM domains.
 * A single cell is used as an index into an array of PM domains specified in
 * the genpd_onecell_data struct when registering the provider.
 */
struct generic_pm_domain *__of_genpd_xlate_onecell(
                                        struct of_phandle_args *genpdspec,
                                        void *data)
{
        struct genpd_onecell_data *genpd_data = data;
        unsigned int idx = genpdspec->args[0];

        if (genpdspec->args_count != 1)
                return ERR_PTR(-EINVAL);

        if (idx >= genpd_data->num_domains) {
                pr_err("%s: invalid domain index %u\n", __func__, idx);
                return ERR_PTR(-EINVAL);
        }

        if (!genpd_data->domains[idx])
                return ERR_PTR(-ENOENT);

        return genpd_data->domains[idx];
}
EXPORT_SYMBOL_GPL(__of_genpd_xlate_onecell);

/**
 * __of_genpd_add_provider() - Register a PM domain provider for a node
 * @np: Device node pointer associated with the PM domain provider.
 * @xlate: Callback for decoding PM domain from phandle arguments.
 * @data: Context pointer for @xlate callback.
 */
int __of_genpd_add_provider(struct device_node *np, genpd_xlate_t xlate,
                        void *data)
{
        struct of_genpd_provider *cp;

        cp = kzalloc(sizeof(*cp), GFP_KERNEL);
        if (!cp)
                return -ENOMEM;

        cp->node = of_node_get(np);
        cp->data = data;
        cp->xlate = xlate;

        mutex_lock(&of_genpd_mutex);
        list_add(&cp->link, &of_genpd_providers);
        mutex_unlock(&of_genpd_mutex);
        pr_debug("Added domain provider from %s\n", np->full_name);

        return 0;
}
EXPORT_SYMBOL_GPL(__of_genpd_add_provider);

/**
 * of_genpd_del_provider() - Remove a previously registered PM domain provider
 * @np: Device node pointer associated with the PM domain provider
 */
void of_genpd_del_provider(struct device_node *np)
{
        struct of_genpd_provider *cp;

        mutex_lock(&of_genpd_mutex);
        list_for_each_entry(cp, &of_genpd_providers, link) {
                if (cp->node == np) {
                        list_del(&cp->link);
                        of_node_put(cp->node);
                        kfree(cp);
                        break;
                }
        }
        mutex_unlock(&of_genpd_mutex);
}
EXPORT_SYMBOL_GPL(of_genpd_del_provider);

/**
 * of_genpd_get_from_provider() - Look-up PM domain
 * @genpdspec: OF phandle args to use for look-up
 *
 * Looks for a PM domain provider under the node specified by @genpdspec and if
 * found, uses xlate function of the provider to map phandle args to a PM
 * domain.
 *
 * Returns a valid pointer to struct generic_pm_domain on success or ERR_PTR()
 * on failure.
 */
struct generic_pm_domain *of_genpd_get_from_provider(
                                        struct of_phandle_args *genpdspec)
{
        struct generic_pm_domain *genpd = ERR_PTR(-ENOENT);
        struct of_genpd_provider *provider;

        mutex_lock(&of_genpd_mutex);

        /* Check if we have such a provider in our array */
        list_for_each_entry(provider, &of_genpd_providers, link) {
                if (provider->node == genpdspec->np)
                        genpd = provider->xlate(genpdspec, provider->data);
                if (!IS_ERR(genpd))
                        break;
        }

        mutex_unlock(&of_genpd_mutex);

        return genpd;
}
EXPORT_SYMBOL_GPL(of_genpd_get_from_provider);

/**
 * genpd_dev_pm_detach - Detach a device from its PM domain.
 * @dev: Device to detach.
 * @power_off: Currently not used
 *
 * Try to locate a corresponding generic PM domain, which the device was
 * attached to previously. If such is found, the device is detached from it.
 */
static void genpd_dev_pm_detach(struct device *dev, bool power_off)
{
        struct generic_pm_domain *pd;
        unsigned int i;
        int ret = 0;

        pd = pm_genpd_lookup_dev(dev);
        if (!pd)
                return;

        dev_dbg(dev, "removing from PM domain %s\n", pd->name);

        for (i = 1; i < GENPD_RETRY_MAX_MS; i <<= 1) {
                ret = pm_genpd_remove_device(pd, dev);
                if (ret != -EAGAIN)
                        break;

                mdelay(i);
                cond_resched();
        }

        if (ret < 0) {
                dev_err(dev, "failed to remove from PM domain %s: %d",
                        pd->name, ret);
                return;
        }

        /* Check if PM domain can be powered off after removing this device. */
        genpd_queue_power_off_work(pd);
}

static void genpd_dev_pm_sync(struct device *dev)
{
        struct generic_pm_domain *pd;

        pd = dev_to_genpd(dev);
        if (IS_ERR(pd))
                return;

        genpd_queue_power_off_work(pd);
}

/**
 * genpd_dev_pm_attach - Attach a device to its PM domain using DT.
 * @dev: Device to attach.
 *
 * Parse device's OF node to find a PM domain specifier. If such is found,
 * attaches the device to retrieved pm_domain ops.
 *
 * Both generic and legacy Samsung-specific DT bindings are supported to keep
 * backwards compatibility with existing DTBs.
 *
 * Returns 0 on successfully attached PM domain or negative error code. Note
 * that if a power-domain exists for the device, but it cannot be found or
 * turned on, then return -EPROBE_DEFER to ensure that the device is not
 * probed and to re-try again later.
 */
int genpd_dev_pm_attach(struct device *dev)
{
        struct of_phandle_args pd_args;
        struct generic_pm_domain *pd;
        unsigned int i;
        int ret;

        if (!dev->of_node)
                return -ENODEV;

        if (dev->pm_domain)
                return -EEXIST;

        ret = of_parse_phandle_with_args(dev->of_node, "power-domains",
                                        "#power-domain-cells", 0, &pd_args);
        if (ret < 0) {
                if (ret != -ENOENT)
                        return ret;

                /*
                 * Try legacy Samsung-specific bindings
                 * (for backwards compatibility of DT ABI)
                 */
                pd_args.args_count = 0;
                pd_args.np = of_parse_phandle(dev->of_node,
                                                "samsung,power-domain", 0);
                if (!pd_args.np)
                        return -ENOENT;
        }

        pd = of_genpd_get_from_provider(&pd_args);
        of_node_put(pd_args.np);
        if (IS_ERR(pd)) {
                dev_dbg(dev, "%s() failed to find PM domain: %ld\n",
                        __func__, PTR_ERR(pd));
                return -EPROBE_DEFER;
        }

        dev_dbg(dev, "adding to PM domain %s\n", pd->name);

        for (i = 1; i < GENPD_RETRY_MAX_MS; i <<= 1) {
                ret = pm_genpd_add_device(pd, dev);
                if (ret != -EAGAIN)
                        break;

                mdelay(i);
                cond_resched();
        }

        if (ret < 0) {
                dev_err(dev, "failed to add to PM domain %s: %d",
                        pd->name, ret);
                goto out;
        }

        dev->pm_domain->detach = genpd_dev_pm_detach;
        dev->pm_domain->sync = genpd_dev_pm_sync;
        ret = genpd_poweron(pd);

out:
        return ret ? -EPROBE_DEFER : 0;
}
EXPORT_SYMBOL_GPL(genpd_dev_pm_attach);
#endif /* CONFIG_PM_GENERIC_DOMAINS_OF */


/***        debugfs support        ***/

#ifdef CONFIG_PM_ADVANCED_DEBUG
#include <linux/pm.h>
#include <linux/device.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/init.h>
#include <linux/kobject.h>
static struct dentry *pm_genpd_debugfs_dir;

/*
 * TODO: This function is a slightly modified version of rtpm_status_show
 * from sysfs.c, so generalize it.
 */
static void rtpm_status_str(struct seq_file *s, struct device *dev)
{
        static const char * const status_lookup[] = {
                [RPM_ACTIVE] = "active",
                [RPM_RESUMING] = "resuming",
                [RPM_SUSPENDED] = "suspended",
                [RPM_SUSPENDING] = "suspending"
        };
        const char *p = "";

        if (dev->power.runtime_error)
                p = "error";
        else if (dev->power.disable_depth)
                p = "unsupported";
        else if (dev->power.runtime_status < ARRAY_SIZE(status_lookup))
                p = status_lookup[dev->power.runtime_status];
        else
                WARN_ON(1);

        seq_puts(s, p);
}

static int pm_genpd_summary_one(struct seq_file *s,
                                struct generic_pm_domain *genpd)
{
        static const char * const status_lookup[] = {
                [GPD_STATE_ACTIVE] = "on",
                [GPD_STATE_POWER_OFF] = "off"
        };
        struct pm_domain_data *pm_data;
        const char *kobj_path;
        struct gpd_link *link;
        int ret;

        ret = mutex_lock_interruptible(&genpd->lock);
        if (ret)
                return -ERESTARTSYS;

        if (WARN_ON(genpd->status >= ARRAY_SIZE(status_lookup)))
                goto exit;
        seq_printf(s, "%-30s  %-15s ", genpd->name, status_lookup[genpd->status]);

        /*
         * Modifications on the list require holding locks on both
         * master and slave, so we are safe.
         * Also genpd->name is immutable.
         */
        list_for_each_entry(link, &genpd->master_links, master_node) {
                seq_printf(s, "%s", link->slave->name);
                if (!list_is_last(&link->master_node, &genpd->master_links))
                        seq_puts(s, ", ");
        }

        list_for_each_entry(pm_data, &genpd->dev_list, list_node) {
                kobj_path = kobject_get_path(&pm_data->dev->kobj, GFP_KERNEL);
                if (kobj_path == NULL)
                        continue;

                seq_printf(s, "\n    %-50s  ", kobj_path);
                rtpm_status_str(s, pm_data->dev);
                kfree(kobj_path);
        }

        seq_puts(s, "\n");
exit:
        mutex_unlock(&genpd->lock);

        return 0;
}

static int pm_genpd_summary_show(struct seq_file *s, void *data)
{
        struct generic_pm_domain *genpd;
        int ret = 0;

        seq_puts(s, "domain                          status          slaves\n");
        seq_puts(s, "    /device                                             runtime status\n");
        seq_puts(s, "----------------------------------------------------------------------\n");

        ret = mutex_lock_interruptible(&gpd_list_lock);
        if (ret)
                return -ERESTARTSYS;

        list_for_each_entry(genpd, &gpd_list, gpd_list_node) {
                ret = pm_genpd_summary_one(s, genpd);
                if (ret)
                        break;
        }
        mutex_unlock(&gpd_list_lock);

        return ret;
}

static int pm_genpd_summary_open(struct inode *inode, struct file *file)
{
        return single_open(file, pm_genpd_summary_show, NULL);
}

static const struct file_operations pm_genpd_summary_fops = {
        .open = pm_genpd_summary_open,
        .read = seq_read,
        .llseek = seq_lseek,
        .release = single_release,
};

static int __init pm_genpd_debug_init(void)
{
        struct dentry *d;

        pm_genpd_debugfs_dir = debugfs_create_dir("pm_genpd", NULL);

        if (!pm_genpd_debugfs_dir)
                return -ENOMEM;

        d = debugfs_create_file("pm_genpd_summary", S_IRUGO,
                        pm_genpd_debugfs_dir, NULL, &pm_genpd_summary_fops);
        if (!d)
                return -ENOMEM;

        return 0;
}
late_initcall(pm_genpd_debug_init);

static void __exit pm_genpd_debug_exit(void)
{
        debugfs_remove_recursive(pm_genpd_debugfs_dir);
}
__exitcall(pm_genpd_debug_exit);
#endif /* CONFIG_PM_ADVANCED_DEBUG */