// SPDX-License-Identifier: GPL-2.0
/*
 * drivers/base/power/domain.c - Common code related to device power domains.
 *
 * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
 */
#define pr_fmt(fmt) "PM: " fmt

#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/platform_device.h>
#include <linux/pm_opp.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 <linux/cpu.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);

struct genpd_lock_ops {
        void (*lock)(struct generic_pm_domain *genpd);
        void (*lock_nested)(struct generic_pm_domain *genpd, int depth);
        int (*lock_interruptible)(struct generic_pm_domain *genpd);
        void (*unlock)(struct generic_pm_domain *genpd);
};

static void genpd_lock_mtx(struct generic_pm_domain *genpd)
{
        mutex_lock(&genpd->mlock);
}

static void genpd_lock_nested_mtx(struct generic_pm_domain *genpd,
                                        int depth)
{
        mutex_lock_nested(&genpd->mlock, depth);
}

static int genpd_lock_interruptible_mtx(struct generic_pm_domain *genpd)
{
        return mutex_lock_interruptible(&genpd->mlock);
}

static void genpd_unlock_mtx(struct generic_pm_domain *genpd)
{
        return mutex_unlock(&genpd->mlock);
}

static const struct genpd_lock_ops genpd_mtx_ops = {
        .lock = genpd_lock_mtx,
        .lock_nested = genpd_lock_nested_mtx,
        .lock_interruptible = genpd_lock_interruptible_mtx,
        .unlock = genpd_unlock_mtx,
};

static void genpd_lock_spin(struct generic_pm_domain *genpd)
        __acquires(&genpd->slock)
{
        unsigned long flags;

        spin_lock_irqsave(&genpd->slock, flags);
        genpd->lock_flags = flags;
}

static void genpd_lock_nested_spin(struct generic_pm_domain *genpd,
                                        int depth)
        __acquires(&genpd->slock)
{
        unsigned long flags;

        spin_lock_irqsave_nested(&genpd->slock, flags, depth);
        genpd->lock_flags = flags;
}

static int genpd_lock_interruptible_spin(struct generic_pm_domain *genpd)
        __acquires(&genpd->slock)
{
        unsigned long flags;

        spin_lock_irqsave(&genpd->slock, flags);
        genpd->lock_flags = flags;
        return 0;
}

static void genpd_unlock_spin(struct generic_pm_domain *genpd)
        __releases(&genpd->slock)
{
        spin_unlock_irqrestore(&genpd->slock, genpd->lock_flags);
}

static const struct genpd_lock_ops genpd_spin_ops = {
        .lock = genpd_lock_spin,
        .lock_nested = genpd_lock_nested_spin,
        .lock_interruptible = genpd_lock_interruptible_spin,
        .unlock = genpd_unlock_spin,
};

#define genpd_lock(p)                   p->lock_ops->lock(p)
#define genpd_lock_nested(p, d)         p->lock_ops->lock_nested(p, d)
#define genpd_lock_interruptible(p)     p->lock_ops->lock_interruptible(p)
#define genpd_unlock(p)                 p->lock_ops->unlock(p)

#define genpd_status_on(genpd)          (genpd->status == GPD_STATE_ACTIVE)
#define genpd_is_irq_safe(genpd)        (genpd->flags & GENPD_FLAG_IRQ_SAFE)
#define genpd_is_always_on(genpd)       (genpd->flags & GENPD_FLAG_ALWAYS_ON)
#define genpd_is_active_wakeup(genpd)   (genpd->flags & GENPD_FLAG_ACTIVE_WAKEUP)
#define genpd_is_cpu_domain(genpd)      (genpd->flags & GENPD_FLAG_CPU_DOMAIN)
#define genpd_is_rpm_always_on(genpd)   (genpd->flags & GENPD_FLAG_RPM_ALWAYS_ON)

static inline bool irq_safe_dev_in_no_sleep_domain(struct device *dev,
                const struct generic_pm_domain *genpd)
{
        bool ret;

        ret = pm_runtime_is_irq_safe(dev) && !genpd_is_irq_safe(genpd);

        /*
         * Warn once if an IRQ safe device is attached to a no sleep domain, as
         * to indicate a suboptimal configuration for PM. For an always on
         * domain this isn't case, thus don't warn.
         */
        if (ret && !genpd_is_always_on(genpd))
                dev_warn_once(dev, "PM domain %s will not be powered off\n",
                                genpd->name);

        return ret;
}

static int genpd_runtime_suspend(struct device *dev);

/*
 * 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.
 */
static struct generic_pm_domain *dev_to_genpd_safe(struct device *dev)
{
        if (IS_ERR_OR_NULL(dev) || IS_ERR_OR_NULL(dev->pm_domain))
                return NULL;

        /* A genpd's always have its ->runtime_suspend() callback assigned. */
        if (dev->pm_domain->ops.runtime_suspend == genpd_runtime_suspend)
                return pd_to_genpd(dev->pm_domain);

        return NULL;
}

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

static int genpd_start_dev(const 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();
}

#ifdef CONFIG_DEBUG_FS
static void genpd_update_accounting(struct generic_pm_domain *genpd)
{
        ktime_t delta, now;

        now = ktime_get();
        delta = ktime_sub(now, genpd->accounting_time);

        /*
         * If genpd->status is active, it means we are just
         * out of off and so update the idle time and vice
         * versa.
         */
        if (genpd->status == GPD_STATE_ACTIVE) {
                int state_idx = genpd->state_idx;

                genpd->states[state_idx].idle_time =
                        ktime_add(genpd->states[state_idx].idle_time, delta);
        } else {
                genpd->on_time = ktime_add(genpd->on_time, delta);
        }

        genpd->accounting_time = now;
}
#else
static inline void genpd_update_accounting(struct generic_pm_domain *genpd) {}
#endif

static int _genpd_reeval_performance_state(struct generic_pm_domain *genpd,
                                           unsigned int state)
{
        struct generic_pm_domain_data *pd_data;
        struct pm_domain_data *pdd;
        struct gpd_link *link;

        /* New requested state is same as Max requested state */
        if (state == genpd->performance_state)
                return state;

        /* New requested state is higher than Max requested state */
        if (state > genpd->performance_state)
                return state;

        /* Traverse all devices within the domain */
        list_for_each_entry(pdd, &genpd->dev_list, list_node) {
                pd_data = to_gpd_data(pdd);

                if (pd_data->performance_state > state)
                        state = pd_data->performance_state;
        }

        /*
         * Traverse all sub-domains within the domain. This can be
         * done without any additional locking as the link->performance_state
         * field is protected by the parent genpd->lock, which is already taken.
         *
         * Also note that link->performance_state (subdomain's performance state
         * requirement to parent domain) is different from
         * link->child->performance_state (current performance state requirement
         * of the devices/sub-domains of the subdomain) and so can have a
         * different value.
         *
         * Note that we also take vote from powered-off sub-domains into account
         * as the same is done for devices right now.
         */
        list_for_each_entry(link, &genpd->parent_links, parent_node) {
                if (link->performance_state > state)
                        state = link->performance_state;
        }

        return state;
}

static int _genpd_set_performance_state(struct generic_pm_domain *genpd,
                                        unsigned int state, int depth)
{
        struct generic_pm_domain *parent;
        struct gpd_link *link;
        int parent_state, ret;

        if (state == genpd->performance_state)
                return 0;

        /* Propagate to parents of genpd */
        list_for_each_entry(link, &genpd->child_links, child_node) {
                parent = link->parent;

                if (!parent->set_performance_state)
                        continue;

                /* Find parent's performance state */
                ret = dev_pm_opp_xlate_performance_state(genpd->opp_table,
                                                         parent->opp_table,
                                                         state);
                if (unlikely(ret < 0))
                        goto err;

                parent_state = ret;

                genpd_lock_nested(parent, depth + 1);

                link->prev_performance_state = link->performance_state;
                link->performance_state = parent_state;
                parent_state = _genpd_reeval_performance_state(parent,
                                                parent_state);
                ret = _genpd_set_performance_state(parent, parent_state, depth + 1);
                if (ret)
                        link->performance_state = link->prev_performance_state;

                genpd_unlock(parent);

                if (ret)
                        goto err;
        }

        ret = genpd->set_performance_state(genpd, state);
        if (ret)
                goto err;

        genpd->performance_state = state;
        return 0;

err:
        /* Encountered an error, lets rollback */
        list_for_each_entry_continue_reverse(link, &genpd->child_links,
                                             child_node) {
                parent = link->parent;

                if (!parent->set_performance_state)
                        continue;

                genpd_lock_nested(parent, depth + 1);

                parent_state = link->prev_performance_state;
                link->performance_state = parent_state;

                parent_state = _genpd_reeval_performance_state(parent,
                                                parent_state);
                if (_genpd_set_performance_state(parent, parent_state, depth + 1)) {
                        pr_err("%s: Failed to roll back to %d performance state\n",
                               parent->name, parent_state);
                }

                genpd_unlock(parent);
        }

        return ret;
}

/**
 * dev_pm_genpd_set_performance_state- Set performance state of device's power
 * domain.
 *
 * @dev: Device for which the performance-state needs to be set.
 * @state: Target performance state of the device. This can be set as 0 when the
 *         device doesn't have any performance state constraints left (And so
 *         the device wouldn't participate anymore to find the target
 *         performance state of the genpd).
 *
 * It is assumed that the users guarantee that the genpd wouldn't be detached
 * while this routine is getting called.
 *
 * Returns 0 on success and negative error values on failures.
 */
int dev_pm_genpd_set_performance_state(struct device *dev, unsigned int state)
{
        struct generic_pm_domain *genpd;
        struct generic_pm_domain_data *gpd_data;
        unsigned int prev;
        int ret;

        genpd = dev_to_genpd_safe(dev);
        if (!genpd)
                return -ENODEV;

        if (unlikely(!genpd->set_performance_state))
                return -EINVAL;

        if (WARN_ON(!dev->power.subsys_data ||
                     !dev->power.subsys_data->domain_data))
                return -EINVAL;

        genpd_lock(genpd);

        gpd_data = to_gpd_data(dev->power.subsys_data->domain_data);
        prev = gpd_data->performance_state;
        gpd_data->performance_state = state;

        state = _genpd_reeval_performance_state(genpd, state);
        ret = _genpd_set_performance_state(genpd, state, 0);
        if (ret)
                gpd_data->performance_state = prev;

        genpd_unlock(genpd);

        return ret;
}
EXPORT_SYMBOL_GPL(dev_pm_genpd_set_performance_state);

static int _genpd_power_on(struct generic_pm_domain *genpd, bool timed)
{
        unsigned int state_idx = genpd->state_idx;
        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->states[state_idx].power_on_latency_ns)
                return ret;

        genpd->states[state_idx].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)
{
        unsigned int state_idx = genpd->state_idx;
        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)
                return ret;

        elapsed_ns = ktime_to_ns(ktime_sub(ktime_get(), time_start));
        if (elapsed_ns <= genpd->states[state_idx].power_off_latency_ns)
                return 0;

        genpd->states[state_idx].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 0;
}

/**
 * genpd_queue_power_off_work - Queue up the execution of genpd_power_off().
 * @genpd: PM domain to power off.
 *
 * Queue up the execution of genpd_power_off() 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_power_off - Remove power from a given PM domain.
 * @genpd: PM domain to power down.
 * @one_dev_on: If invoked from genpd's ->runtime_suspend|resume() callback, the
 * RPM status of the releated device is in an intermediate state, not yet turned
 * into RPM_SUSPENDED. This means genpd_power_off() must allow one device to not
 * be RPM_SUSPENDED, while it tries to power off the PM domain.
 *
 * 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_power_off(struct generic_pm_domain *genpd, bool one_dev_on,
                           unsigned int depth)
{
        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_on(genpd) || genpd->prepared_count > 0)
                return 0;

        /*
         * Abort power off for the PM domain in the following situations:
         * (1) The domain is configured as always on.
         * (2) When the domain has a subdomain being powered on.
         */
        if (genpd_is_always_on(genpd) ||
                        genpd_is_rpm_always_on(genpd) ||
                        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);
                if (stat > PM_QOS_FLAGS_NONE)
                        return -EBUSY;

                /*
                 * Do not allow PM domain to be powered off, when an IRQ safe
                 * device is part of a non-IRQ safe domain.
                 */
                if (!pm_runtime_suspended(pdd->dev) ||
                        irq_safe_dev_in_no_sleep_domain(pdd->dev, genpd))
                        not_suspended++;
        }

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

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

        /* Default to shallowest state. */
        if (!genpd->gov)
                genpd->state_idx = 0;

        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_power_on() for the parent yet after
                 * incrementing it.  In that case genpd_power_on() will wait
                 * for us to drop the lock, so we can call .power_off() and let
                 * the genpd_power_on() 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;
        genpd_update_accounting(genpd);

        list_for_each_entry(link, &genpd->child_links, child_node) {
                genpd_sd_counter_dec(link->parent);
                genpd_lock_nested(link->parent, depth + 1);
                genpd_power_off(link->parent, false, depth + 1);
                genpd_unlock(link->parent);
        }

        return 0;
}

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

        if (genpd_status_on(genpd))
                return 0;

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

                genpd_sd_counter_inc(parent);

                genpd_lock_nested(parent, depth + 1);
                ret = genpd_power_on(parent, depth + 1);
                genpd_unlock(parent);

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

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

        genpd->status = GPD_STATE_ACTIVE;
        genpd_update_accounting(genpd);

        return 0;

 err:
        list_for_each_entry_continue_reverse(link,
                                        &genpd->child_links,
                                        child_node) {
                genpd_sd_counter_dec(link->parent);
                genpd_lock_nested(link->parent, depth + 1);
                genpd_power_off(link->parent, false, depth + 1);
                genpd_unlock(link->parent);
        }

        return ret;
}

static int genpd_dev_pm_start(struct device *dev)
{
        struct generic_pm_domain *genpd = dev_to_genpd(dev);

        return genpd_start_dev(genpd, 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) {
                        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)) {
                        genpd_lock(genpd);
                        genpd->max_off_time_changed = true;
                        genpd_unlock(genpd);
                }

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

        return NOTIFY_DONE;
}

/**
 * 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);

        genpd_lock(genpd);
        genpd_power_off(genpd, false, 0);
        genpd_unlock(genpd);
}

/**
 * __genpd_runtime_suspend - walk the hierarchy of ->runtime_suspend() callbacks
 * @dev: Device to handle.
 */
static int __genpd_runtime_suspend(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;
}

/**
 * __genpd_runtime_resume - walk the hierarchy of ->runtime_resume() callbacks
 * @dev: Device to handle.
 */
static int __genpd_runtime_resume(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;
}

/**
 * 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 genpd_runtime_suspend(struct device *dev)
{
        struct generic_pm_domain *genpd;
        bool (*suspend_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.
         */
        suspend_ok = genpd->gov ? genpd->gov->suspend_ok : NULL;
        if (runtime_pm && suspend_ok && !suspend_ok(dev))
                return -EBUSY;

        /* Measure suspend latency. */
        time_start = 0;
        if (runtime_pm)
                time_start = ktime_get();

        ret = __genpd_runtime_suspend(dev);
        if (ret)
                return ret;

        ret = genpd_stop_dev(genpd, dev);
        if (ret) {
                __genpd_runtime_resume(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 may be run with
         * IRQs disabled, so suspend only if the PM domain also is irq_safe.
         */
        if (irq_safe_dev_in_no_sleep_domain(dev, genpd))
                return 0;

        genpd_lock(genpd);
        genpd_power_off(genpd, true, 0);
        genpd_unlock(genpd);

        return 0;
}

/**
 * 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 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;

        /*
         * As we don't power off a non IRQ safe domain, which holds
         * an IRQ safe device, we don't need to restore power to it.
         */
        if (irq_safe_dev_in_no_sleep_domain(dev, genpd)) {
                timed = false;
                goto out;
        }

        genpd_lock(genpd);
        ret = genpd_power_on(genpd, 0);
        genpd_unlock(genpd);

        if (ret)
                return ret;

 out:
        /* Measure resume latency. */
        time_start = 0;
        if (timed && runtime_pm)
                time_start = ktime_get();

        ret = genpd_start_dev(genpd, dev);
        if (ret)
                goto err_poweroff;

        ret = __genpd_runtime_resume(dev);
        if (ret)
                goto err_stop;

        /* 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;

err_stop:
        genpd_stop_dev(genpd, dev);
err_poweroff:
        if (!pm_runtime_is_irq_safe(dev) ||
                (pm_runtime_is_irq_safe(dev) && genpd_is_irq_safe(genpd))) {
                genpd_lock(genpd);
                genpd_power_off(genpd, true, 0);
                genpd_unlock(genpd);
        }

        return ret;
}

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_power_off_unused - Power off all PM domains with no devices in use.
 */
static int __init genpd_power_off_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_power_off_unused);

#ifdef CONFIG_PM_SLEEP

/**
 * genpd_sync_power_off - Synchronously power off a PM domain and its parents.
 * @genpd: PM domain to power off, if possible.
 * @use_lock: use the lock.
 * @depth: nesting count for lockdep.
 *
 * 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 parents.
 *
 * This function is only called in "noirq" and "syscore" stages of system power
 * transitions. The "noirq" callbacks may be executed asynchronously, thus in
 * these cases the lock must be held.
 */
static void genpd_sync_power_off(struct generic_pm_domain *genpd, bool use_lock,
                                 unsigned int depth)
{
        struct gpd_link *link;

        if (!genpd_status_on(genpd) || genpd_is_always_on(genpd))
                return;

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

        /* Choose the deepest state when suspending */
        genpd->state_idx = genpd->state_count - 1;
        if (_genpd_power_off(genpd, false))
                return;

        genpd->status = GPD_STATE_POWER_OFF;

        list_for_each_entry(link, &genpd->child_links, child_node) {
                genpd_sd_counter_dec(link->parent);

                if (use_lock)
                        genpd_lock_nested(link->parent, depth + 1);

                genpd_sync_power_off(link->parent, use_lock, depth + 1);

                if (use_lock)
                        genpd_unlock(link->parent);
        }
}

/**
 * genpd_sync_power_on - Synchronously power on a PM domain and its parents.
 * @genpd: PM domain to power on.
 * @use_lock: use the lock.
 * @depth: nesting count for lockdep.
 *
 * This function is only called in "noirq" and "syscore" stages of system power
 * transitions. The "noirq" callbacks may be executed asynchronously, thus in
 * these cases the lock must be held.
 */
static void genpd_sync_power_on(struct generic_pm_domain *genpd, bool use_lock,
                                unsigned int depth)
{
        struct gpd_link *link;

        if (genpd_status_on(genpd))
                return;

        list_for_each_entry(link, &genpd->child_links, child_node) {
                genpd_sd_counter_inc(link->parent);

                if (use_lock)

                        genpd_lock_nested(link->parent, depth + 1);

                genpd_sync_power_on(link->parent, use_lock, depth + 1);

                if (use_lock)
                        genpd_unlock(link->parent);
        }

        _genpd_power_on(genpd, false);

        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 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,
                          const struct generic_pm_domain *genpd)
{
        bool active_wakeup;

        if (!device_can_wakeup(dev))
                return false;

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

/**
 * 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 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.
         */
        if (resume_needed(dev, genpd))
                pm_runtime_resume(dev);

        genpd_lock(genpd);

        if (genpd->prepared_count++ == 0)
                genpd->suspended_count = 0;

        genpd_unlock(genpd);

        ret = pm_generic_prepare(dev);
        if (ret < 0) {
                genpd_lock(genpd);

                genpd->prepared_count--;

                genpd_unlock(genpd);
        }

        /* Never return 1, as genpd don't cope with the direct_complete path. */
        return ret >= 0 ? 0 : ret;
}

/**
 * genpd_finish_suspend - Completion of suspend or hibernation of device in an
 *   I/O pm domain.
 * @dev: Device to suspend.
 * @poweroff: Specifies if this is a poweroff_noirq or suspend_noirq callback.
 *
 * Stop the device and remove power from the domain if all devices in it have
 * been stopped.
 */
static int genpd_finish_suspend(struct device *dev, bool poweroff)
{
        struct generic_pm_domain *genpd;
        int ret = 0;

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

        if (poweroff)
                ret = pm_generic_poweroff_noirq(dev);
        else
                ret = pm_generic_suspend_noirq(dev);
        if (ret)
                return ret;

        if (dev->power.wakeup_path && genpd_is_active_wakeup(genpd))
                return 0;

        if (genpd->dev_ops.stop && genpd->dev_ops.start &&
            !pm_runtime_status_suspended(dev)) {
                ret = genpd_stop_dev(genpd, dev);
                if (ret) {
                        if (poweroff)
                                pm_generic_restore_noirq(dev);
                        else
                                pm_generic_resume_noirq(dev);
                        return ret;
                }
        }

        genpd_lock(genpd);
        genpd->suspended_count++;
        genpd_sync_power_off(genpd, true, 0);
        genpd_unlock(genpd);

        return 0;
}

/**
 * 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 genpd_suspend_noirq(struct device *dev)
{
        dev_dbg(dev, "%s()\n", __func__);

        return genpd_finish_suspend(dev, false);
}

/**
 * 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 genpd_resume_noirq(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 (dev->power.wakeup_path && genpd_is_active_wakeup(genpd))
                return pm_generic_resume_noirq(dev);

        genpd_lock(genpd);
        genpd_sync_power_on(genpd, true, 0);
        genpd->suspended_count--;
        genpd_unlock(genpd);

        if (genpd->dev_ops.stop && genpd->dev_ops.start &&
            !pm_runtime_status_suspended(dev)) {
                ret = genpd_start_dev(genpd, dev);
                if (ret)
                        return ret;
        }

        return pm_generic_resume_noirq(dev);
}

/**
 * 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 genpd_freeze_noirq(struct device *dev)
{
        const struct generic_pm_domain *genpd;
        int ret = 0;

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

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

        ret = pm_generic_freeze_noirq(dev);
        if (ret)
                return ret;

        if (genpd->dev_ops.stop && genpd->dev_ops.start &&
            !pm_runtime_status_suspended(dev))
                ret = genpd_stop_dev(genpd, dev);

        return ret;
}

/**
 * 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 genpd_thaw_noirq(struct device *dev)
{
        const struct generic_pm_domain *genpd;
        int ret = 0;

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

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

        if (genpd->dev_ops.stop && genpd->dev_ops.start &&
            !pm_runtime_status_suspended(dev)) {
                ret = genpd_start_dev(genpd, dev);
                if (ret)
                        return ret;
        }

        return pm_generic_thaw_noirq(dev);
}

/**
 * genpd_poweroff_noirq - Completion of hibernation of device in an
 *   I/O PM domain.
 * @dev: Device to poweroff.
 *
 * Stop the device and remove power from the domain if all devices in it have
 * been stopped.
 */
static int genpd_poweroff_noirq(struct device *dev)
{
        dev_dbg(dev, "%s()\n", __func__);

        return genpd_finish_suspend(dev, true);
}

/**
 * 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 genpd_restore_noirq(struct device *dev)
{
        struct generic_pm_domain *genpd;
        int ret = 0;

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

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

        /*
         * At this point suspended_count == 0 means we are being run for the
         * first time for the given domain in the present cycle.
         */
        genpd_lock(genpd);
        if (genpd->suspended_count++ == 0)
                /*
                 * The boot kernel might put the domain into arbitrary state,
                 * so make it appear as powered off to genpd_sync_power_on(),
                 * so that it tries to power it on in case it was really off.
                 */
                genpd->status = GPD_STATE_POWER_OFF;

        genpd_sync_power_on(genpd, true, 0);
        genpd_unlock(genpd);

        if (genpd->dev_ops.stop && genpd->dev_ops.start &&
            !pm_runtime_status_suspended(dev)) {
                ret = genpd_start_dev(genpd, dev);
                if (ret)
                        return ret;
        }

        return pm_generic_restore_noirq(dev);
}

/**
 * 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 genpd_complete(struct device *dev)
{
        struct generic_pm_domain *genpd;

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

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

        pm_generic_complete(dev);

        genpd_lock(genpd);

        genpd->prepared_count--;
        if (!genpd->prepared_count)
                genpd_queue_power_off_work(genpd);

        genpd_unlock(genpd);
}

/**
 * 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_safe(dev);
        if (!genpd)
                return;

        if (suspend) {
                genpd->suspended_count++;
                genpd_sync_power_off(genpd, false, 0);
        } else {
                genpd_sync_power_on(genpd, false, 0);
                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 genpd_prepare           NULL
#define genpd_suspend_noirq     NULL
#define genpd_resume_noirq      NULL
#define genpd_freeze_noirq      NULL
#define genpd_thaw_noirq        NULL
#define genpd_poweroff_noirq    NULL
#define genpd_restore_noirq     NULL
#define genpd_complete          NULL

#endif /* CONFIG_PM_SLEEP */

static struct generic_pm_domain_data *genpd_alloc_dev_data(struct device *dev)
{
        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;
        }

        gpd_data->base.dev = dev;
        gpd_data->td.constraint_changed = true;
        gpd_data->td.effective_constraint_ns = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT_NS;
        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);

        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)
{
        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);
}

static void genpd_update_cpumask(struct generic_pm_domain *genpd,
                                 int cpu, bool set, unsigned int depth)
{
        struct gpd_link *link;

        if (!genpd_is_cpu_domain(genpd))
                return;

        list_for_each_entry(link, &genpd->child_links, child_node) {
                struct generic_pm_domain *parent = link->parent;

                genpd_lock_nested(parent, depth + 1);
                genpd_update_cpumask(parent, cpu, set, depth + 1);
                genpd_unlock(parent);
        }

        if (set)
                cpumask_set_cpu(cpu, genpd->cpus);
        else
                cpumask_clear_cpu(cpu, genpd->cpus);
}

static void genpd_set_cpumask(struct generic_pm_domain *genpd, int cpu)
{
        if (cpu >= 0)
                genpd_update_cpumask(genpd, cpu, true, 0);
}

static void genpd_clear_cpumask(struct generic_pm_domain *genpd, int cpu)
{
        if (cpu >= 0)
                genpd_update_cpumask(genpd, cpu, false, 0);
}

static int genpd_get_cpu(struct generic_pm_domain *genpd, struct device *dev)
{
        int cpu;

        if (!genpd_is_cpu_domain(genpd))
                return -1;

        for_each_possible_cpu(cpu) {
                if (get_cpu_device(cpu) == dev)
                        return cpu;
        }

        return -1;
}

static int genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
                            struct device *base_dev)
{
        struct generic_pm_domain_data *gpd_data;
        int ret;

        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);
        if (IS_ERR(gpd_data))
                return PTR_ERR(gpd_data);

        gpd_data->cpu = genpd_get_cpu(genpd, base_dev);

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

        genpd_lock(genpd);

        genpd_set_cpumask(genpd, gpd_data->cpu);
        dev_pm_domain_set(dev, &genpd->domain);

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

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

        genpd_unlock(genpd);
 out:
        if (ret)
                genpd_free_dev_data(dev, gpd_data);
        else
                dev_pm_qos_add_notifier(dev, &gpd_data->nb,
                                        DEV_PM_QOS_RESUME_LATENCY);

        return ret;
}

/**
 * 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.
 */
int pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev)
{
        int ret;

        mutex_lock(&gpd_list_lock);
        ret = genpd_add_device(genpd, dev, dev);
        mutex_unlock(&gpd_list_lock);

        return ret;
}
EXPORT_SYMBOL_GPL(pm_genpd_add_device);

static int 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__);

        pdd = dev->power.subsys_data->domain_data;
        gpd_data = to_gpd_data(pdd);
        dev_pm_qos_remove_notifier(dev, &gpd_data->nb,
                                   DEV_PM_QOS_RESUME_LATENCY);

        genpd_lock(genpd);

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

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

        genpd_clear_cpumask(genpd, gpd_data->cpu);
        dev_pm_domain_set(dev, NULL);

        list_del_init(&pdd->list_node);

        genpd_unlock(genpd);

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

        genpd_free_dev_data(dev, gpd_data);

        return 0;

 out:
        genpd_unlock(genpd);
        dev_pm_qos_add_notifier(dev, &gpd_data->nb, DEV_PM_QOS_RESUME_LATENCY);

        return ret;
}

/**
 * pm_genpd_remove_device - Remove a device from an I/O PM domain.
 * @dev: Device to be removed.
 */
int pm_genpd_remove_device(struct device *dev)
{
        struct generic_pm_domain *genpd = dev_to_genpd_safe(dev);

        if (!genpd)
                return -EINVAL;

        return genpd_remove_device(genpd, dev);
}
EXPORT_SYMBOL_GPL(pm_genpd_remove_device);

static int 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;

        /*
         * If the domain can be powered on/off in an IRQ safe
         * context, ensure that the subdomain can also be
         * powered on/off in that context.
         */
        if (!genpd_is_irq_safe(genpd) && genpd_is_irq_safe(subdomain)) {
                WARN(1, "Parent %s of subdomain %s must be IRQ safe\n",
                                genpd->name, subdomain->name);
                return -EINVAL;
        }

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

        genpd_lock(subdomain);
        genpd_lock_nested(genpd, SINGLE_DEPTH_NESTING);

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

        list_for_each_entry(itr, &genpd->parent_links, parent_node) {
                if (itr->child == subdomain && itr->parent == genpd) {
                        ret = -EINVAL;
                        goto out;
                }
        }

        link->parent = genpd;
        list_add_tail(&link->parent_node, &genpd->parent_links);
        link->child = subdomain;
        list_add_tail(&link->child_node, &subdomain->child_links);
        if (genpd_status_on(subdomain))
                genpd_sd_counter_inc(genpd);

 out:
        genpd_unlock(genpd);
        genpd_unlock(subdomain);
        if (ret)
                kfree(link);
        return ret;
}

/**
 * pm_genpd_add_subdomain - Add a subdomain to an I/O PM domain.
 * @genpd: Leader 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)
{
        int ret;

        mutex_lock(&gpd_list_lock);
        ret = genpd_add_subdomain(genpd, subdomain);
        mutex_unlock(&gpd_list_lock);

        return ret;
}
EXPORT_SYMBOL_GPL(pm_genpd_add_subdomain);

/**
 * pm_genpd_remove_subdomain - Remove a subdomain from an I/O PM domain.
 * @genpd: Leader 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 *l, *link;
        int ret = -EINVAL;

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

        genpd_lock(subdomain);
        genpd_lock_nested(genpd, SINGLE_DEPTH_NESTING);

        if (!list_empty(&subdomain->parent_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_safe(link, l, &genpd->parent_links, parent_node) {
                if (link->child != subdomain)
                        continue;

                list_del(&link->parent_node);
                list_del(&link->child_node);
                kfree(link);
                if (genpd_status_on(subdomain))
                        genpd_sd_counter_dec(genpd);

                ret = 0;
                break;
        }

out:
        genpd_unlock(genpd);
        genpd_unlock(subdomain);

        return ret;
}
EXPORT_SYMBOL_GPL(pm_genpd_remove_subdomain);

static void genpd_free_default_power_state(struct genpd_power_state *states,
                                           unsigned int state_count)
{
        kfree(states);
}

static int genpd_set_default_power_state(struct generic_pm_domain *genpd)
{
        struct genpd_power_state *state;

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

        genpd->states = state;
        genpd->state_count = 1;
        genpd->free_states = genpd_free_default_power_state;

        return 0;
}

static void genpd_lock_init(struct generic_pm_domain *genpd)
{
        if (genpd->flags & GENPD_FLAG_IRQ_SAFE) {
                spin_lock_init(&genpd->slock);
                genpd->lock_ops = &genpd_spin_ops;
        } else {
                mutex_init(&genpd->mlock);
                genpd->lock_ops = &genpd_mtx_ops;
        }
}

/**
 * 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.
 *
 * Returns 0 on successful initialization, else a negative error code.
 */
int pm_genpd_init(struct generic_pm_domain *genpd,
                  struct dev_power_governor *gov, bool is_off)
{
        int ret;

        if (IS_ERR_OR_NULL(genpd))
                return -EINVAL;

        INIT_LIST_HEAD(&genpd->parent_links);
        INIT_LIST_HEAD(&genpd->child_links);
        INIT_LIST_HEAD(&genpd->dev_list);
        genpd_lock_init(genpd);
        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->provider = NULL;
        genpd->has_provider = false;
        genpd->accounting_time = ktime_get();
        genpd->domain.ops.runtime_suspend = genpd_runtime_suspend;
        genpd->domain.ops.runtime_resume = genpd_runtime_resume;
        genpd->domain.ops.prepare = genpd_prepare;
        genpd->domain.ops.suspend_noirq = genpd_suspend_noirq;
        genpd->domain.ops.resume_noirq = genpd_resume_noirq;
        genpd->domain.ops.freeze_noirq = genpd_freeze_noirq;
        genpd->domain.ops.thaw_noirq = genpd_thaw_noirq;
        genpd->domain.ops.poweroff_noirq = genpd_poweroff_noirq;
        genpd->domain.ops.restore_noirq = genpd_restore_noirq;
        genpd->domain.ops.complete = genpd_complete;
        genpd->domain.start = genpd_dev_pm_start;

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

        /* Always-on domains must be powered on at initialization. */
        if ((genpd_is_always_on(genpd) || genpd_is_rpm_always_on(genpd)) &&
                        !genpd_status_on(genpd))
                return -EINVAL;

        if (genpd_is_cpu_domain(genpd) &&
            !zalloc_cpumask_var(&genpd->cpus, GFP_KERNEL))
                return -ENOMEM;

        /* Use only one "off" state if there were no states declared */
        if (genpd->state_count == 0) {
                ret = genpd_set_default_power_state(genpd);
                if (ret) {
                        if (genpd_is_cpu_domain(genpd))
                                free_cpumask_var(genpd->cpus);
                        return ret;
                }
        } else if (!gov && genpd->state_count > 1) {
                pr_warn("%s: no governor for states\n", genpd->name);
        }

        device_initialize(&genpd->dev);
        dev_set_name(&genpd->dev, "%s", genpd->name);

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

        return 0;
}
EXPORT_SYMBOL_GPL(pm_genpd_init);

static int genpd_remove(struct generic_pm_domain *genpd)
{
        struct gpd_link *l, *link;

        if (IS_ERR_OR_NULL(genpd))
                return -EINVAL;

        genpd_lock(genpd);

        if (genpd->has_provider) {
                genpd_unlock(genpd);
                pr_err("Provider present, unable to remove %s\n", genpd->name);
                return -EBUSY;
        }

        if (!list_empty(&genpd->parent_links) || genpd->device_count) {
                genpd_unlock(genpd);
                pr_err("%s: unable to remove %s\n", __func__, genpd->name);
                return -EBUSY;
        }

        list_for_each_entry_safe(link, l, &genpd->child_links, child_node) {
                list_del(&link->parent_node);
                list_del(&link->child_node);
                kfree(link);
        }

        list_del(&genpd->gpd_list_node);
        genpd_unlock(genpd);
        cancel_work_sync(&genpd->power_off_work);
        if (genpd_is_cpu_domain(genpd))
                free_cpumask_var(genpd->cpus);
        if (genpd->free_states)
                genpd->free_states(genpd->states, genpd->state_count);

        pr_debug("%s: removed %s\n", __func__, genpd->name);

        return 0;
}

/**
 * pm_genpd_remove - Remove a generic I/O PM domain
 * @genpd: Pointer to PM domain that is to be removed.
 *
 * To remove the PM domain, this function:
 *  - Removes the PM domain as a subdomain to any parent domains,
 *    if it was added.
 *  - Removes the PM domain from the list of registered PM domains.
 *
 * The PM domain will only be removed, if the associated provider has
 * been removed, it is not a parent to any other PM domain and has no
 * devices associated with it.
 */
int pm_genpd_remove(struct generic_pm_domain *genpd)
{
        int ret;

        mutex_lock(&gpd_list_lock);
        ret = genpd_remove(genpd);
        mutex_unlock(&gpd_list_lock);

        return ret;
}
EXPORT_SYMBOL_GPL(pm_genpd_remove);

#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:
 *  - genpd_xlate_simple() for 1:1 device tree node to PM domain mapping.
 *  - 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);

/**
 * 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.
 */
static struct generic_pm_domain *genpd_xlate_simple(
                                        struct of_phandle_args *genpdspec,
                                        void *data)
{
        return data;
}

/**
 * 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.
 */
static struct generic_pm_domain *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];
}

/**
 * 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.
 */
static int 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 %pOF\n", np);

        return 0;
}

static bool genpd_present(const struct generic_pm_domain *genpd)
{
        const struct generic_pm_domain *gpd;

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

/**
 * of_genpd_add_provider_simple() - Register a simple PM domain provider
 * @np: Device node pointer associated with the PM domain provider.
 * @genpd: Pointer to PM domain associated with the PM domain provider.
 */
int of_genpd_add_provider_simple(struct device_node *np,
                                 struct generic_pm_domain *genpd)
{
        int ret = -EINVAL;

        if (!np || !genpd)
                return -EINVAL;

        mutex_lock(&gpd_list_lock);

        if (!genpd_present(genpd))
                goto unlock;

        genpd->dev.of_node = np;

        /* Parse genpd OPP table */
        if (genpd->set_performance_state) {
                ret = dev_pm_opp_of_add_table(&genpd->dev);
                if (ret) {
                        dev_err(&genpd->dev, "Failed to add OPP table: %d\n",
                                ret);
                        goto unlock;
                }

                /*
                 * Save table for faster processing while setting performance
                 * state.
                 */
                genpd->opp_table = dev_pm_opp_get_opp_table(&genpd->dev);
                WARN_ON(!genpd->opp_table);
        }

        ret = genpd_add_provider(np, genpd_xlate_simple, genpd);
        if (ret) {
                if (genpd->set_performance_state) {
                        dev_pm_opp_put_opp_table(genpd->opp_table);
                        dev_pm_opp_of_remove_table(&genpd->dev);
                }

                goto unlock;
        }

        genpd->provider = &np->fwnode;
        genpd->has_provider = true;

unlock:
        mutex_unlock(&gpd_list_lock);

        return ret;
}
EXPORT_SYMBOL_GPL(of_genpd_add_provider_simple);

/**
 * of_genpd_add_provider_onecell() - Register a onecell PM domain provider
 * @np: Device node pointer associated with the PM domain provider.
 * @data: Pointer to the data associated with the PM domain provider.
 */
int of_genpd_add_provider_onecell(struct device_node *np,
                                  struct genpd_onecell_data *data)
{
        struct generic_pm_domain *genpd;
        unsigned int i;
        int ret = -EINVAL;

        if (!np || !data)
                return -EINVAL;

        mutex_lock(&gpd_list_lock);

        if (!data->xlate)
                data->xlate = genpd_xlate_onecell;

        for (i = 0; i < data->num_domains; i++) {
                genpd = data->domains[i];

                if (!genpd)
                        continue;
                if (!genpd_present(genpd))
                        goto error;

                genpd->dev.of_node = np;

                /* Parse genpd OPP table */
                if (genpd->set_performance_state) {
                        ret = dev_pm_opp_of_add_table_indexed(&genpd->dev, i);
                        if (ret) {
                                dev_err(&genpd->dev, "Failed to add OPP table for index %d: %d\n",
                                        i, ret);
                                goto error;
                        }

                        /*
                         * Save table for faster processing while setting
                         * performance state.
                         */
                        genpd->opp_table = dev_pm_opp_get_opp_table_indexed(&genpd->dev, i);
                        WARN_ON(!genpd->opp_table);
                }

                genpd->provider = &np->fwnode;
                genpd->has_provider = true;
        }

        ret = genpd_add_provider(np, data->xlate, data);
        if (ret < 0)
                goto error;

        mutex_unlock(&gpd_list_lock);

        return 0;

error:
        while (i--) {
                genpd = data->domains[i];

                if (!genpd)
                        continue;

                genpd->provider = NULL;
                genpd->has_provider = false;

                if (genpd->set_performance_state) {
                        dev_pm_opp_put_opp_table(genpd->opp_table);
                        dev_pm_opp_of_remove_table(&genpd->dev);
                }
        }

        mutex_unlock(&gpd_list_lock);

        return ret;
}
EXPORT_SYMBOL_GPL(of_genpd_add_provider_onecell);

/**
 * 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, *tmp;
        struct generic_pm_domain *gpd;

        mutex_lock(&gpd_list_lock);
        mutex_lock(&of_genpd_mutex);
        list_for_each_entry_safe(cp, tmp, &of_genpd_providers, link) {
                if (cp->node == np) {
                        /*
                         * For each PM domain associated with the
                         * provider, set the 'has_provider' to false
                         * so that the PM domain can be safely removed.
                         */
                        list_for_each_entry(gpd, &gpd_list, gpd_list_node) {
                                if (gpd->provider == &np->fwnode) {
                                        gpd->has_provider = false;

                                        if (!gpd->set_performance_state)
                                                continue;

                                        dev_pm_opp_put_opp_table(gpd->opp_table);
                                        dev_pm_opp_of_remove_table(&gpd->dev);
                                }
                        }

                        list_del(&cp->link);
                        of_node_put(cp->node);
                        kfree(cp);
                        break;
                }
        }
        mutex_unlock(&of_genpd_mutex);
        mutex_unlock(&gpd_list_lock);
}
EXPORT_SYMBOL_GPL(of_genpd_del_provider);

/**
 * 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.
 */
static struct generic_pm_domain *genpd_get_from_provider(
                                        struct of_phandle_args *genpdspec)
{
        struct generic_pm_domain *genpd = ERR_PTR(-ENOENT);
        struct of_genpd_provider *provider;

        if (!genpdspec)
                return ERR_PTR(-EINVAL);

        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;
}

/**
 * of_genpd_add_device() - Add a device to an I/O PM domain
 * @genpdspec: OF phandle args to use for look-up PM domain
 * @dev: Device to be added.
 *
 * Looks-up an I/O PM domain based upon phandle args provided and adds
 * the device to the PM domain. Returns a negative error code on failure.
 */
int of_genpd_add_device(struct of_phandle_args *genpdspec, struct device *dev)
{
        struct generic_pm_domain *genpd;
        int ret;

        mutex_lock(&gpd_list_lock);

        genpd = genpd_get_from_provider(genpdspec);
        if (IS_ERR(genpd)) {
                ret = PTR_ERR(genpd);
                goto out;
        }

        ret = genpd_add_device(genpd, dev, dev);

out:
        mutex_unlock(&gpd_list_lock);

        return ret;
}
EXPORT_SYMBOL_GPL(of_genpd_add_device);

/**
 * of_genpd_add_subdomain - Add a subdomain to an I/O PM domain.
 * @parent_spec: OF phandle args to use for parent PM domain look-up
 * @subdomain_spec: OF phandle args to use for subdomain look-up
 *
 * Looks-up a parent PM domain and subdomain based upon phandle args
 * provided and adds the subdomain to the parent PM domain. Returns a
 * negative error code on failure.
 */
int of_genpd_add_subdomain(struct of_phandle_args *parent_spec,
                           struct of_phandle_args *subdomain_spec)
{
        struct generic_pm_domain *parent, *subdomain;
        int ret;

        mutex_lock(&gpd_list_lock);

        parent = genpd_get_from_provider(parent_spec);
        if (IS_ERR(parent)) {
                ret = PTR_ERR(parent);
                goto out;
        }

        subdomain = genpd_get_from_provider(subdomain_spec);
        if (IS_ERR(subdomain)) {
                ret = PTR_ERR(subdomain);
                goto out;
        }

        ret = genpd_add_subdomain(parent, subdomain);

out:
        mutex_unlock(&gpd_list_lock);

        return ret;
}
EXPORT_SYMBOL_GPL(of_genpd_add_subdomain);

/**
 * of_genpd_remove_subdomain - Remove a subdomain from an I/O PM domain.
 * @parent_spec: OF phandle args to use for parent PM domain look-up
 * @subdomain_spec: OF phandle args to use for subdomain look-up
 *
 * Looks-up a parent PM domain and subdomain based upon phandle args
 * provided and removes the subdomain from the parent PM domain. Returns a
 * negative error code on failure.
 */
int of_genpd_remove_subdomain(struct of_phandle_args *parent_spec,
                              struct of_phandle_args *subdomain_spec)
{
        struct generic_pm_domain *parent, *subdomain;
        int ret;

        mutex_lock(&gpd_list_lock);

        parent = genpd_get_from_provider(parent_spec);
        if (IS_ERR(parent)) {
                ret = PTR_ERR(parent);
                goto out;
        }

        subdomain = genpd_get_from_provider(subdomain_spec);
        if (IS_ERR(subdomain)) {
                ret = PTR_ERR(subdomain);
                goto out;
        }

        ret = pm_genpd_remove_subdomain(parent, subdomain);

out:
        mutex_unlock(&gpd_list_lock);

        return ret;
}
EXPORT_SYMBOL_GPL(of_genpd_remove_subdomain);

/**
 * of_genpd_remove_last - Remove the last PM domain registered for a provider
 * @provider: Pointer to device structure associated with provider
 *
 * Find the last PM domain that was added by a particular provider and
 * remove this PM domain from the list of PM domains. The provider is
 * identified by the 'provider' device structure that is passed. The PM
 * domain will only be removed, if the provider associated with domain
 * has been removed.
 *
 * Returns a valid pointer to struct generic_pm_domain on success or
 * ERR_PTR() on failure.
 */
struct generic_pm_domain *of_genpd_remove_last(struct device_node *np)
{
        struct generic_pm_domain *gpd, *tmp, *genpd = ERR_PTR(-ENOENT);
        int ret;

        if (IS_ERR_OR_NULL(np))
                return ERR_PTR(-EINVAL);

        mutex_lock(&gpd_list_lock);
        list_for_each_entry_safe(gpd, tmp, &gpd_list, gpd_list_node) {
                if (gpd->provider == &np->fwnode) {
                        ret = genpd_remove(gpd);
                        genpd = ret ? ERR_PTR(ret) : gpd;
                        break;
                }
        }
        mutex_unlock(&gpd_list_lock);

        return genpd;
}
EXPORT_SYMBOL_GPL(of_genpd_remove_last);

static void genpd_release_dev(struct device *dev)
{
        of_node_put(dev->of_node);
        kfree(dev);
}

static struct bus_type genpd_bus_type = {
        .name           = "genpd",
};

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

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

        for (i = 1; i < GENPD_RETRY_MAX_MS; i <<= 1) {
                ret = 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);

        /* Unregister the device if it was created by genpd. */
        if (dev->bus == &genpd_bus_type)
                device_unregister(dev);
}

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);
}

static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
                                 unsigned int index, bool power_on)
{
        struct of_phandle_args pd_args;
        struct generic_pm_domain *pd;
        int ret;

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

        mutex_lock(&gpd_list_lock);
        pd = genpd_get_from_provider(&pd_args);
        of_node_put(pd_args.np);
        if (IS_ERR(pd)) {
                mutex_unlock(&gpd_list_lock);
                dev_dbg(dev, "%s() failed to find PM domain: %ld\n",
                        __func__, PTR_ERR(pd));
                return driver_deferred_probe_check_state(base_dev);
        }

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

        ret = genpd_add_device(pd, dev, base_dev);
        mutex_unlock(&gpd_list_lock);

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

        dev->pm_domain->detach = genpd_dev_pm_detach;
        dev->pm_domain->sync = genpd_dev_pm_sync;

        if (power_on) {
                genpd_lock(pd);
                ret = genpd_power_on(pd, 0);
                genpd_unlock(pd);
        }

        if (ret)
                genpd_remove_device(pd, dev);

        return ret ? -EPROBE_DEFER : 1;
}

/**
 * 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.
 *
 * Returns 1 on successfully attached PM domain, 0 when the device don't need a
 * PM domain or when multiple power-domains exists for it, else a 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)
{
        if (!dev->of_node)
                return 0;

        /*
         * Devices with multiple PM domains must be attached separately, as we
         * can only attach one PM domain per device.
         */
        if (of_count_phandle_with_args(dev->of_node, "power-domains",
                                       "#power-domain-cells") != 1)
                return 0;

        return __genpd_dev_pm_attach(dev, dev, 0, true);
}
EXPORT_SYMBOL_GPL(genpd_dev_pm_attach);

/**
 * genpd_dev_pm_attach_by_id - Associate a device with one of its PM domains.
 * @dev: The device used to lookup the PM domain.
 * @index: The index of the PM domain.
 *
 * Parse device's OF node to find a PM domain specifier at the provided @index.
 * If such is found, creates a virtual device and attaches it to the retrieved
 * pm_domain ops. To deal with detaching of the virtual device, the ->detach()
 * callback in the struct dev_pm_domain are assigned to genpd_dev_pm_detach().
 *
 * Returns the created virtual device if successfully attached PM domain, NULL
 * when the device don't need a PM domain, else an ERR_PTR() in case of
 * failures. If a power-domain exists for the device, but cannot be found or
 * turned on, then ERR_PTR(-EPROBE_DEFER) is returned to ensure that the device
 * is not probed and to re-try again later.
 */
struct device *genpd_dev_pm_attach_by_id(struct device *dev,
                                         unsigned int index)
{
        struct device *virt_dev;
        int num_domains;
        int ret;

        if (!dev->of_node)
                return NULL;

        /* Verify that the index is within a valid range. */
        num_domains = of_count_phandle_with_args(dev->of_node, "power-domains",
                                                 "#power-domain-cells");
        if (index >= num_domains)
                return NULL;

        /* Allocate and register device on the genpd bus. */
        virt_dev = kzalloc(sizeof(*virt_dev), GFP_KERNEL);
        if (!virt_dev)
                return ERR_PTR(-ENOMEM);

        dev_set_name(virt_dev, "genpd:%u:%s", index, dev_name(dev));
        virt_dev->bus = &genpd_bus_type;
        virt_dev->release = genpd_release_dev;
        virt_dev->of_node = of_node_get(dev->of_node);

        ret = device_register(virt_dev);
        if (ret) {
                put_device(virt_dev);
                return ERR_PTR(ret);
        }

        /* Try to attach the device to the PM domain at the specified index. */
        ret = __genpd_dev_pm_attach(virt_dev, dev, index, false);
        if (ret < 1) {
                device_unregister(virt_dev);
                return ret ? ERR_PTR(ret) : NULL;
        }

        pm_runtime_enable(virt_dev);
        genpd_queue_power_off_work(dev_to_genpd(virt_dev));

        return virt_dev;
}
EXPORT_SYMBOL_GPL(genpd_dev_pm_attach_by_id);

/**
 * genpd_dev_pm_attach_by_name - Associate a device with one of its PM domains.
 * @dev: The device used to lookup the PM domain.
 * @name: The name of the PM domain.
 *
 * Parse device's OF node to find a PM domain specifier using the
 * power-domain-names DT property. For further description see
 * genpd_dev_pm_attach_by_id().
 */
struct device *genpd_dev_pm_attach_by_name(struct device *dev, const char *name)
{
        int index;

        if (!dev->of_node)
                return NULL;

        index = of_property_match_string(dev->of_node, "power-domain-names",
                                         name);
        if (index < 0)
                return NULL;

        return genpd_dev_pm_attach_by_id(dev, index);
}

static const struct of_device_id idle_state_match[] = {
        { .compatible = "domain-idle-state", },
        { }
};

static int genpd_parse_state(struct genpd_power_state *genpd_state,
                                    struct device_node *state_node)
{
        int err;
        u32 residency;
        u32 entry_latency, exit_latency;

        err = of_property_read_u32(state_node, "entry-latency-us",
                                                &entry_latency);
        if (err) {
                pr_debug(" * %pOF missing entry-latency-us property\n",
                         state_node);
                return -EINVAL;
        }

        err = of_property_read_u32(state_node, "exit-latency-us",
                                                &exit_latency);
        if (err) {
                pr_debug(" * %pOF missing exit-latency-us property\n",
                         state_node);
                return -EINVAL;
        }

        err = of_property_read_u32(state_node, "min-residency-us", &residency);
        if (!err)
                genpd_state->residency_ns = 1000 * residency;

        genpd_state->power_on_latency_ns = 1000 * exit_latency;
        genpd_state->power_off_latency_ns = 1000 * entry_latency;
        genpd_state->fwnode = &state_node->fwnode;

        return 0;
}

static int genpd_iterate_idle_states(struct device_node *dn,
                                     struct genpd_power_state *states)
{
        int ret;
        struct of_phandle_iterator it;
        struct device_node *np;
        int i = 0;

        ret = of_count_phandle_with_args(dn, "domain-idle-states", NULL);
        if (ret <= 0)
                return ret == -ENOENT ? 0 : ret;

        /* Loop over the phandles until all the requested entry is found */
        of_for_each_phandle(&it, ret, dn, "domain-idle-states", NULL, 0) {
                np = it.node;
                if (!of_match_node(idle_state_match, np))
                        continue;
                if (states) {
                        ret = genpd_parse_state(&states[i], np);
                        if (ret) {
                                pr_err("Parsing idle state node %pOF failed with err %d\n",
                                       np, ret);
                                of_node_put(np);
                                return ret;
                        }
                }
                i++;
        }

        return i;
}

/**
 * of_genpd_parse_idle_states: Return array of idle states for the genpd.
 *
 * @dn: The genpd device node
 * @states: The pointer to which the state array will be saved.
 * @n: The count of elements in the array returned from this function.
 *
 * Returns the device states parsed from the OF node. The memory for the states
 * is allocated by this function and is the responsibility of the caller to
 * free the memory after use. If any or zero compatible domain idle states is
 * found it returns 0 and in case of errors, a negative error code is returned.
 */
int of_genpd_parse_idle_states(struct device_node *dn,
                        struct genpd_power_state **states, int *n)
{
        struct genpd_power_state *st;
        int ret;

        ret = genpd_iterate_idle_states(dn, NULL);
        if (ret < 0)
                return ret;

        if (!ret) {
                *states = NULL;
                *n = 0;
                return 0;
        }

        st = kcalloc(ret, sizeof(*st), GFP_KERNEL);
        if (!st)
                return -ENOMEM;

        ret = genpd_iterate_idle_states(dn, st);
        if (ret <= 0) {
                kfree(st);
                return ret < 0 ? ret : -EINVAL;
        }

        *states = st;
        *n = ret;

        return 0;
}
EXPORT_SYMBOL_GPL(of_genpd_parse_idle_states);

/**
 * pm_genpd_opp_to_performance_state - Gets performance state of the genpd from its OPP node.
 *
 * @genpd_dev: Genpd's device for which the performance-state needs to be found.
 * @opp: struct dev_pm_opp of the OPP for which we need to find performance
 *      state.
 *
 * Returns performance state encoded in the OPP of the genpd. This calls
 * platform specific genpd->opp_to_performance_state() callback to translate
 * power domain OPP to performance state.
 *
 * Returns performance state on success and 0 on failure.
 */
unsigned int pm_genpd_opp_to_performance_state(struct device *genpd_dev,
                                               struct dev_pm_opp *opp)
{
        struct generic_pm_domain *genpd = NULL;
        int state;

        genpd = container_of(genpd_dev, struct generic_pm_domain, dev);

        if (unlikely(!genpd->opp_to_performance_state))
                return 0;

        genpd_lock(genpd);
        state = genpd->opp_to_performance_state(genpd, opp);
        genpd_unlock(genpd);

        return state;
}
EXPORT_SYMBOL_GPL(pm_genpd_opp_to_performance_state);

static int __init genpd_bus_init(void)
{
        return bus_register(&genpd_bus_type);
}
core_initcall(genpd_bus_init);

#endif /* CONFIG_PM_GENERIC_DOMAINS_OF */


/***        debugfs support        ***/

#ifdef CONFIG_DEBUG_FS
#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 *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 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;
        char state[16];
        int ret;

        ret = genpd_lock_interruptible(genpd);
        if (ret)
                return -ERESTARTSYS;

        if (WARN_ON(genpd->status >= ARRAY_SIZE(status_lookup)))
                goto exit;
        if (!genpd_status_on(genpd))
                snprintf(state, sizeof(state), "%s-%u",
                         status_lookup[genpd->status], genpd->state_idx);
        else
                snprintf(state, sizeof(state), "%s",
                         status_lookup[genpd->status]);
        seq_printf(s, "%-30s  %-15s ", genpd->name, state);

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

        list_for_each_entry(pm_data, &genpd->dev_list, list_node) {
                kobj_path = kobject_get_path(&pm_data->dev->kobj,
                                genpd_is_irq_safe(genpd) ?
                                GFP_ATOMIC : 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:
        genpd_unlock(genpd);

        return 0;
}

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

        seq_puts(s, "domain                          status          children\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 = genpd_summary_one(s, genpd);
                if (ret)
                        break;
        }
        mutex_unlock(&gpd_list_lock);

        return ret;
}

static int status_show(struct seq_file *s, void *data)
{
        static const char * const status_lookup[] = {
                [GPD_STATE_ACTIVE] = "on",
                [GPD_STATE_POWER_OFF] = "off"
        };

        struct generic_pm_domain *genpd = s->private;
        int ret = 0;

        ret = genpd_lock_interruptible(genpd);
        if (ret)
                return -ERESTARTSYS;

        if (WARN_ON_ONCE(genpd->status >= ARRAY_SIZE(status_lookup)))
                goto exit;

        if (genpd->status == GPD_STATE_POWER_OFF)
                seq_printf(s, "%s-%u\n", status_lookup[genpd->status],
                        genpd->state_idx);
        else
                seq_printf(s, "%s\n", status_lookup[genpd->status]);
exit:
        genpd_unlock(genpd);
        return ret;
}

static int sub_domains_show(struct seq_file *s, void *data)
{
        struct generic_pm_domain *genpd = s->private;
        struct gpd_link *link;
        int ret = 0;

        ret = genpd_lock_interruptible(genpd);
        if (ret)
                return -ERESTARTSYS;

        list_for_each_entry(link, &genpd->parent_links, parent_node)
                seq_printf(s, "%s\n", link->child->name);

        genpd_unlock(genpd);
        return ret;
}

static int idle_states_show(struct seq_file *s, void *data)
{
        struct generic_pm_domain *genpd = s->private;
        unsigned int i;
        int ret = 0;

        ret = genpd_lock_interruptible(genpd);
        if (ret)
                return -ERESTARTSYS;

        seq_puts(s, "State          Time Spent(ms)\n");

        for (i = 0; i < genpd->state_count; i++) {
                ktime_t delta = 0;
                s64 msecs;

                if ((genpd->status == GPD_STATE_POWER_OFF) &&
                                (genpd->state_idx == i))
                        delta = ktime_sub(ktime_get(), genpd->accounting_time);

                msecs = ktime_to_ms(
                        ktime_add(genpd->states[i].idle_time, delta));
                seq_printf(s, "S%-13i %lld\n", i, msecs);
        }

        genpd_unlock(genpd);
        return ret;
}

static int active_time_show(struct seq_file *s, void *data)
{
        struct generic_pm_domain *genpd = s->private;
        ktime_t delta = 0;
        int ret = 0;

        ret = genpd_lock_interruptible(genpd);
        if (ret)
                return -ERESTARTSYS;

        if (genpd->status == GPD_STATE_ACTIVE)
                delta = ktime_sub(ktime_get(), genpd->accounting_time);

        seq_printf(s, "%lld ms\n", ktime_to_ms(
                                ktime_add(genpd->on_time, delta)));

        genpd_unlock(genpd);
        return ret;
}

static int total_idle_time_show(struct seq_file *s, void *data)
{
        struct generic_pm_domain *genpd = s->private;
        ktime_t delta = 0, total = 0;
        unsigned int i;
        int ret = 0;

        ret = genpd_lock_interruptible(genpd);
        if (ret)
                return -ERESTARTSYS;

        for (i = 0; i < genpd->state_count; i++) {

                if ((genpd->status == GPD_STATE_POWER_OFF) &&
                                (genpd->state_idx == i))
                        delta = ktime_sub(ktime_get(), genpd->accounting_time);

                total = ktime_add(total, genpd->states[i].idle_time);
        }
        total = ktime_add(total, delta);

        seq_printf(s, "%lld ms\n", ktime_to_ms(total));

        genpd_unlock(genpd);
        return ret;
}

static int devices_show(struct seq_file *s, void *data)
{
        struct generic_pm_domain *genpd = s->private;
        struct pm_domain_data *pm_data;
        const char *kobj_path;
        int ret = 0;

        ret = genpd_lock_interruptible(genpd);
        if (ret)
                return -ERESTARTSYS;

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

                seq_printf(s, "%s\n", kobj_path);
                kfree(kobj_path);
        }

        genpd_unlock(genpd);
        return ret;
}

static int perf_state_show(struct seq_file *s, void *data)
{
        struct generic_pm_domain *genpd = s->private;

        if (genpd_lock_interruptible(genpd))
                return -ERESTARTSYS;

        seq_printf(s, "%u\n", genpd->performance_state);

        genpd_unlock(genpd);
        return 0;
}

DEFINE_SHOW_ATTRIBUTE(summary);
DEFINE_SHOW_ATTRIBUTE(status);
DEFINE_SHOW_ATTRIBUTE(sub_domains);
DEFINE_SHOW_ATTRIBUTE(idle_states);
DEFINE_SHOW_ATTRIBUTE(active_time);
DEFINE_SHOW_ATTRIBUTE(total_idle_time);
DEFINE_SHOW_ATTRIBUTE(devices);
DEFINE_SHOW_ATTRIBUTE(perf_state);

static int __init genpd_debug_init(void)
{
        struct dentry *d;
        struct generic_pm_domain *genpd;

        genpd_debugfs_dir = debugfs_create_dir("pm_genpd", NULL);

        debugfs_create_file("pm_genpd_summary", S_IRUGO, genpd_debugfs_dir,
                            NULL, &summary_fops);

        list_for_each_entry(genpd, &gpd_list, gpd_list_node) {
                d = debugfs_create_dir(genpd->name, genpd_debugfs_dir);

                debugfs_create_file("current_state", 0444,
                                d, genpd, &status_fops);
                debugfs_create_file("sub_domains", 0444,
                                d, genpd, &sub_domains_fops);
                debugfs_create_file("idle_states", 0444,
                                d, genpd, &idle_states_fops);
                debugfs_create_file("active_time", 0444,
                                d, genpd, &active_time_fops);
                debugfs_create_file("total_idle_time", 0444,
                                d, genpd, &total_idle_time_fops);
                debugfs_create_file("devices", 0444,
                                d, genpd, &devices_fops);
                if (genpd->set_performance_state)
                        debugfs_create_file("perf_state", 0444,
                                            d, genpd, &perf_state_fops);
        }

        return 0;
}
late_initcall(genpd_debug_init);

static void __exit genpd_debug_exit(void)
{
        debugfs_remove_recursive(genpd_debugfs_dir);
}
__exitcall(genpd_debug_exit);
#endif /* CONFIG_DEBUG_FS */