xref: /drivers/pmdomain/core.c

// 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/idr.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 <linux/debugfs.h>

/* Provides a unique ID for each genpd device */
static DEFINE_IDA(genpd_ida);

#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,
};

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

	raw_spin_lock_irqsave(&genpd->raw_slock, flags);
	genpd->raw_lock_flags = flags;
}

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

	raw_spin_lock_irqsave_nested(&genpd->raw_slock, flags, depth);
	genpd->raw_lock_flags = flags;
}

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

	raw_spin_lock_irqsave(&genpd->raw_slock, flags);
	genpd->raw_lock_flags = flags;
	return 0;
}

static void genpd_unlock_raw_spin(struct generic_pm_domain *genpd)
	__releases(&genpd->raw_slock)
{
	raw_spin_unlock_irqrestore(&genpd->raw_slock, genpd->raw_lock_flags);
}

static const struct genpd_lock_ops genpd_raw_spin_ops = {
	.lock = genpd_lock_raw_spin,
	.lock_nested = genpd_lock_nested_raw_spin,
	.lock_interruptible = genpd_lock_interruptible_raw_spin,
	.unlock = genpd_unlock_raw_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 == GENPD_STATE_ON)
#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)
#define genpd_is_opp_table_fw(genpd)	(genpd->flags & GENPD_FLAG_OPP_TABLE_FW)
#define genpd_is_dev_name_fw(genpd)	(genpd->flags & GENPD_FLAG_DEV_NAME_FW)

static inline bool irq_safe_dev_in_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 domain, which
	 * callbacks are allowed to sleep. This indicates a suboptimal
	 * configuration for PM, but it doesn't matter for an always on domain.
	 */
	if (genpd_is_always_on(genpd) || genpd_is_rpm_always_on(genpd))
		return ret;

	if (ret)
		dev_warn_once(dev, "PM domain %s will not be powered off\n",
			      dev_name(&genpd->dev));

	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);
}

struct device *dev_to_genpd_dev(struct device *dev)
{
	struct generic_pm_domain *genpd = dev_to_genpd(dev);

	if (IS_ERR(genpd))
		return ERR_CAST(genpd);

	return &genpd->dev;
}

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 struct dentry *genpd_debugfs_dir;

static void genpd_debug_add(struct generic_pm_domain *genpd);

static void genpd_debug_remove(struct generic_pm_domain *genpd)
{
	if (!genpd_debugfs_dir)
		return;

	debugfs_lookup_and_remove(dev_name(&genpd->dev), genpd_debugfs_dir);
}

static void genpd_update_accounting(struct generic_pm_domain *genpd)
{
	u64 delta, now;

	now = ktime_get_mono_fast_ns();
	if (now <= genpd->accounting_time)
		return;

	delta = 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 == GENPD_STATE_ON)
		genpd->states[genpd->state_idx].idle_time += delta;
	else
		genpd->on_time += delta;

	genpd->accounting_time = now;
}
#else
static inline void genpd_debug_add(struct generic_pm_domain *genpd) {}
static inline void genpd_debug_remove(struct generic_pm_domain *genpd) {}
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_xlate_performance_state(struct generic_pm_domain *genpd,
					 struct generic_pm_domain *parent,
					 unsigned int pstate)
{
	if (!parent->set_performance_state)
		return pstate;

	return dev_pm_opp_xlate_performance_state(genpd->opp_table,
						  parent->opp_table,
						  pstate);
}

static int _genpd_set_performance_state(struct generic_pm_domain *genpd,
					unsigned int state, int depth);

static void _genpd_rollback_parent_state(struct gpd_link *link, int depth)
{
	struct generic_pm_domain *parent = link->parent;
	int parent_state;

	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);
}

static int _genpd_set_parent_state(struct generic_pm_domain *genpd,
				   struct gpd_link *link,
				   unsigned int state, int depth)
{
	struct generic_pm_domain *parent = link->parent;
	int parent_state, ret;

	/* Find parent's performance state */
	ret = genpd_xlate_performance_state(genpd, parent, state);
	if (unlikely(ret < 0))
		return ret;

	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);

	return ret;
}

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

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

	/* When scaling up, propagate to parents first in normal order */
	if (state > genpd->performance_state) {
		list_for_each_entry(link, &genpd->child_links, child_node) {
			ret = _genpd_set_parent_state(genpd, link, state, depth);
			if (ret)
				goto rollback_parents_up;
		}
	}

	if (genpd->set_performance_state) {
		ret = genpd->set_performance_state(genpd, state);
		if (ret) {
			if (link)
				goto rollback_parents_up;
			return ret;
		}
	}

	/* When scaling down, propagate to parents last in reverse order */
	if (state < genpd->performance_state) {
		list_for_each_entry_reverse(link, &genpd->child_links, child_node) {
			ret = _genpd_set_parent_state(genpd, link, state, depth);
			if (ret)
				goto rollback_parents_down;
		}
	}

	genpd->performance_state = state;
	return 0;

rollback_parents_up:
	list_for_each_entry_continue_reverse(link, &genpd->child_links, child_node)
		_genpd_rollback_parent_state(link, depth);
	return ret;
rollback_parents_down:
	list_for_each_entry_continue(link, &genpd->child_links, child_node)
		_genpd_rollback_parent_state(link, depth);
	return ret;
}

static int genpd_set_performance_state(struct device *dev, unsigned int state)
{
	struct generic_pm_domain *genpd = dev_to_genpd(dev);
	struct generic_pm_domain_data *gpd_data = dev_gpd_data(dev);
	unsigned int prev_state;
	int ret;

	prev_state = gpd_data->performance_state;
	if (prev_state == state)
		return 0;

	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_state;

	return ret;
}

static int genpd_drop_performance_state(struct device *dev)
{
	unsigned int prev_state = dev_gpd_data(dev)->performance_state;

	if (!genpd_set_performance_state(dev, 0))
		return prev_state;

	return 0;
}

static void genpd_restore_performance_state(struct device *dev,
					    unsigned int state)
{
	if (state)
		genpd_set_performance_state(dev, state);
}

static int genpd_dev_pm_set_performance_state(struct device *dev,
					      unsigned int state)
{
	struct generic_pm_domain *genpd = dev_to_genpd(dev);
	int ret = 0;

	genpd_lock(genpd);
	if (pm_runtime_suspended(dev)) {
		dev_gpd_data(dev)->rpm_pstate = state;
	} else {
		ret = genpd_set_performance_state(dev, state);
		if (!ret)
			dev_gpd_data(dev)->rpm_pstate = 0;
	}
	genpd_unlock(genpd);

	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;

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

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

	return genpd_dev_pm_set_performance_state(dev, state);
}
EXPORT_SYMBOL_GPL(dev_pm_genpd_set_performance_state);

/**
 * dev_pm_genpd_set_next_wakeup - Notify PM framework of an impending wakeup.
 *
 * @dev: Device to handle
 * @next: impending interrupt/wakeup for the device
 *
 *
 * Allow devices to inform of the next wakeup. It's assumed that the users
 * guarantee that the genpd wouldn't be detached while this routine is getting
 * called. Additionally, it's also assumed that @dev isn't runtime suspended
 * (RPM_SUSPENDED)."
 * Although devices are expected to update the next_wakeup after the end of
 * their usecase as well, it is possible the devices themselves may not know
 * about that, so stale @next will be ignored when powering off the domain.
 */
void dev_pm_genpd_set_next_wakeup(struct device *dev, ktime_t next)
{
	struct generic_pm_domain *genpd;
	struct gpd_timing_data *td;

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

	td = to_gpd_data(dev->power.subsys_data->domain_data)->td;
	if (td)
		td->next_wakeup = next;
}
EXPORT_SYMBOL_GPL(dev_pm_genpd_set_next_wakeup);

/**
 * dev_pm_genpd_get_next_hrtimer - Return the next_hrtimer for the genpd
 * @dev: A device that is attached to the genpd.
 *
 * This routine should typically be called for a device, at the point of when a
 * GENPD_NOTIFY_PRE_OFF notification has been sent for it.
 *
 * Returns the aggregated value of the genpd's next hrtimer or KTIME_MAX if no
 * valid value have been set.
 */
ktime_t dev_pm_genpd_get_next_hrtimer(struct device *dev)
{
	struct generic_pm_domain *genpd;

	genpd = dev_to_genpd_safe(dev);
	if (!genpd)
		return KTIME_MAX;

	if (genpd->gd)
		return genpd->gd->next_hrtimer;

	return KTIME_MAX;
}
EXPORT_SYMBOL_GPL(dev_pm_genpd_get_next_hrtimer);

/*
 * dev_pm_genpd_synced_poweroff - Next power off should be synchronous
 *
 * @dev: A device that is attached to the genpd.
 *
 * Allows a consumer of the genpd to notify the provider that the next power off
 * should be synchronous.
 *
 * It is assumed that the users guarantee that the genpd wouldn't be detached
 * while this routine is getting called.
 */
void dev_pm_genpd_synced_poweroff(struct device *dev)
{
	struct generic_pm_domain *genpd;

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

	genpd_lock(genpd);
	genpd->synced_poweroff = true;
	genpd_unlock(genpd);
}
EXPORT_SYMBOL_GPL(dev_pm_genpd_synced_poweroff);

/**
 * dev_pm_genpd_set_hwmode() - Set the HW mode for the device and its PM domain.
 *
 * @dev: Device for which the HW-mode should be changed.
 * @enable: Value to set or unset the HW-mode.
 *
 * Some PM domains can rely on HW signals to control the power for a device. To
 * allow a consumer driver to switch the behaviour for its device in runtime,
 * which may be beneficial from a latency or energy point of view, this function
 * may be called.
 *
 * It is assumed that the users guarantee that the genpd wouldn't be detached
 * while this routine is getting called.
 *
 * Return: Returns 0 on success and negative error values on failures.
 */
int dev_pm_genpd_set_hwmode(struct device *dev, bool enable)
{
	struct generic_pm_domain *genpd;
	int ret = 0;

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

	if (!genpd->set_hwmode_dev)
		return -EOPNOTSUPP;

	genpd_lock(genpd);

	if (dev_gpd_data(dev)->hw_mode == enable)
		goto out;

	ret = genpd->set_hwmode_dev(genpd, dev, enable);
	if (!ret)
		dev_gpd_data(dev)->hw_mode = enable;

out:
	genpd_unlock(genpd);
	return ret;
}
EXPORT_SYMBOL_GPL(dev_pm_genpd_set_hwmode);

/**
 * dev_pm_genpd_get_hwmode() - Get the HW mode setting for the device.
 *
 * @dev: Device for which the current HW-mode setting should be fetched.
 *
 * This helper function allows consumer drivers to fetch the current HW mode
 * setting of its the device.
 *
 * It is assumed that the users guarantee that the genpd wouldn't be detached
 * while this routine is getting called.
 *
 * Return: Returns the HW mode setting of device from SW cached hw_mode.
 */
bool dev_pm_genpd_get_hwmode(struct device *dev)
{
	return dev_gpd_data(dev)->hw_mode;
}
EXPORT_SYMBOL_GPL(dev_pm_genpd_get_hwmode);

/**
 * dev_pm_genpd_rpm_always_on() - Control if the PM domain can be powered off.
 *
 * @dev: Device for which the PM domain may need to stay on for.
 * @on: Value to set or unset for the condition.
 *
 * For some usecases a consumer driver requires its device to remain power-on
 * from the PM domain perspective during runtime. This function allows the
 * behaviour to be dynamically controlled for a device attached to a genpd.
 *
 * It is assumed that the users guarantee that the genpd wouldn't be detached
 * while this routine is getting called.
 *
 * Return: Returns 0 on success and negative error values on failures.
 */
int dev_pm_genpd_rpm_always_on(struct device *dev, bool on)
{
	struct generic_pm_domain *genpd;

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

	genpd_lock(genpd);
	dev_gpd_data(dev)->rpm_always_on = on;
	genpd_unlock(genpd);

	return 0;
}
EXPORT_SYMBOL_GPL(dev_pm_genpd_rpm_always_on);

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;

	/* Notify consumers that we are about to power on. */
	ret = raw_notifier_call_chain_robust(&genpd->power_notifiers,
					     GENPD_NOTIFY_PRE_ON,
					     GENPD_NOTIFY_OFF, NULL);
	ret = notifier_to_errno(ret);
	if (ret)
		return ret;

	if (!genpd->power_on)
		goto out;

	timed = timed && genpd->gd && !genpd->states[state_idx].fwnode;
	if (!timed) {
		ret = genpd->power_on(genpd);
		if (ret)
			goto err;

		goto out;
	}

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

	elapsed_ns = ktime_to_ns(ktime_sub(ktime_get(), time_start));
	if (elapsed_ns <= genpd->states[state_idx].power_on_latency_ns)
		goto out;

	genpd->states[state_idx].power_on_latency_ns = elapsed_ns;
	genpd->gd->max_off_time_changed = true;
	pr_debug("%s: Power-%s latency exceeded, new value %lld ns\n",
		 dev_name(&genpd->dev), "on", elapsed_ns);

out:
	raw_notifier_call_chain(&genpd->power_notifiers, GENPD_NOTIFY_ON, NULL);
	genpd->synced_poweroff = false;
	return 0;
err:
	raw_notifier_call_chain(&genpd->power_notifiers, GENPD_NOTIFY_OFF,
				NULL);
	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;

	/* Notify consumers that we are about to power off. */
	ret = raw_notifier_call_chain_robust(&genpd->power_notifiers,
					     GENPD_NOTIFY_PRE_OFF,
					     GENPD_NOTIFY_ON, NULL);
	ret = notifier_to_errno(ret);
	if (ret)
		return ret;

	if (!genpd->power_off)
		goto out;

	timed = timed && genpd->gd && !genpd->states[state_idx].fwnode;
	if (!timed) {
		ret = genpd->power_off(genpd);
		if (ret)
			goto busy;

		goto out;
	}

	time_start = ktime_get();
	ret = genpd->power_off(genpd);
	if (ret)
		goto busy;

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

	genpd->states[state_idx].power_off_latency_ns = elapsed_ns;
	genpd->gd->max_off_time_changed = true;
	pr_debug("%s: Power-%s latency exceeded, new value %lld ns\n",
		 dev_name(&genpd->dev), "off", elapsed_ns);

out:
	raw_notifier_call_chain(&genpd->power_notifiers, GENPD_NOTIFY_OFF,
				NULL);
	return 0;
busy:
	raw_notifier_call_chain(&genpd->power_notifiers, GENPD_NOTIFY_ON, NULL);
	return ret;
}

/**
 * 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.
 * @depth: nesting count for lockdep.
 *
 * 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;
	int ret;

	/*
	 * 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;

	/*
	 * The children must be in their deepest (powered-off) states to allow
	 * the parent to be powered off. Note that, there's no need for
	 * additional locking, as powering on a child, requires the parent's
	 * lock to be acquired first.
	 */
	list_for_each_entry(link, &genpd->parent_links, parent_node) {
		struct generic_pm_domain *child = link->child;
		if (child->state_idx < child->state_count - 1)
			return -EBUSY;
	}

	list_for_each_entry(pdd, &genpd->dev_list, list_node) {
		/*
		 * 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_sleep_domain(pdd->dev, genpd))
			not_suspended++;

		/* The device may need its PM domain to stay powered on. */
		if (to_gpd_data(pdd)->rpm_always_on)
			return -EBUSY;
	}

	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;

	/* Don't power off, if a child domain is waiting to power on. */
	if (atomic_read(&genpd->sd_count) > 0)
		return -EBUSY;

	ret = _genpd_power_off(genpd, true);
	if (ret) {
		genpd->states[genpd->state_idx].rejected++;
		return ret;
	}

	genpd->status = GENPD_STATE_OFF;
	genpd_update_accounting(genpd);
	genpd->states[genpd->state_idx].usage++;

	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 = GENPD_STATE_ON;
	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 = ERR_PTR(-ENODATA);
		struct pm_domain_data *pdd;
		struct gpd_timing_data *td;

		spin_lock_irq(&dev->power.lock);

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

		spin_unlock_irq(&dev->power.lock);

		if (!IS_ERR(genpd)) {
			genpd_lock(genpd);
			genpd->gd->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 generic_pm_domain_data *gpd_data = dev_gpd_data(dev);
	struct gpd_timing_data *td = gpd_data->td;
	bool runtime_pm = pm_runtime_enabled(dev);
	ktime_t time_start = 0;
	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. */
	if (td && 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 (td && 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->gd->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_sleep_domain(dev, genpd))
		return 0;

	genpd_lock(genpd);
	genpd_power_off(genpd, true, 0);
	gpd_data->rpm_pstate = genpd_drop_performance_state(dev);
	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 generic_pm_domain_data *gpd_data = dev_gpd_data(dev);
	struct gpd_timing_data *td = gpd_data->td;
	bool timed = td && pm_runtime_enabled(dev);
	ktime_t time_start = 0;
	s64 elapsed_ns;
	int ret;

	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_sleep_domain(dev, genpd))
		goto out;

	genpd_lock(genpd);
	genpd_restore_performance_state(dev, gpd_data->rpm_pstate);
	ret = genpd_power_on(genpd, 0);
	genpd_unlock(genpd);

	if (ret)
		return ret;

 out:
	/* Measure resume latency. */
	if (timed)
		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) {
		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->gd->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) || genpd_is_irq_safe(genpd)) {
		genpd_lock(genpd);
		genpd_power_off(genpd, true, 0);
		gpd_data->rpm_pstate = genpd_drop_performance_state(dev);
		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;
	}

	pr_info("genpd: Disabling unused power domains\n");
	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_sync(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;

	/* Check that the children are in their deepest (powered-off) state. */
	list_for_each_entry(link, &genpd->parent_links, parent_node) {
		struct generic_pm_domain *child = link->child;
		if (child->state_idx < child->state_count - 1)
			return;
	}

	/* Choose the deepest state when suspending */
	genpd->state_idx = genpd->state_count - 1;
	if (_genpd_power_off(genpd, false)) {
		genpd->states[genpd->state_idx].rejected++;
		return;
	} else {
		genpd->states[genpd->state_idx].usage++;
	}

	genpd->status = GENPD_STATE_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 = GENPD_STATE_ON;
}

/**
 * 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;

	genpd_lock(genpd);
	genpd->prepared_count++;
	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.
 * @suspend_noirq: Generic suspend_noirq callback.
 * @resume_noirq: Generic resume_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,
				int (*suspend_noirq)(struct device *dev),
				int (*resume_noirq)(struct device *dev))
{
	struct generic_pm_domain *genpd;
	int ret = 0;

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

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

	if (device_wakeup_path(dev) && 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) {
			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,
				    pm_generic_suspend_noirq,
				    pm_generic_resume_noirq);
}

/**
 * genpd_finish_resume - Completion of resume of device in an I/O PM domain.
 * @dev: Device to resume.
 * @resume_noirq: Generic resume_noirq callback.
 *
 * Restore power to the device's PM domain, if necessary, and start the device.
 */
static int genpd_finish_resume(struct device *dev,
			       int (*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 (device_wakeup_path(dev) && genpd_is_active_wakeup(genpd))
		return 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_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)
{
	dev_dbg(dev, "%s()\n", __func__);

	return genpd_finish_resume(dev, pm_generic_resume_noirq);
}

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

	return genpd_finish_suspend(dev,
				    pm_generic_freeze_noirq,
				    pm_generic_thaw_noirq);
}

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

	return genpd_finish_resume(dev, pm_generic_thaw_noirq);
}

/**
 * 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,
				    pm_generic_poweroff_noirq,
				    pm_generic_restore_noirq);
}

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

	return genpd_finish_resume(dev, pm_generic_restore_noirq);
}

/**
 * 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);
}

static void genpd_switch_state(struct device *dev, bool suspend)
{
	struct generic_pm_domain *genpd;
	bool use_lock;

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

	use_lock = genpd_is_irq_safe(genpd);

	if (use_lock)
		genpd_lock(genpd);

	if (suspend) {
		genpd->suspended_count++;
		genpd_sync_power_off(genpd, use_lock, 0);
	} else {
		genpd_sync_power_on(genpd, use_lock, 0);
		genpd->suspended_count--;
	}

	if (use_lock)
		genpd_unlock(genpd);
}

/**
 * dev_pm_genpd_suspend - Synchronously try to suspend the genpd for @dev
 * @dev: The device that is attached to the genpd, that can be suspended.
 *
 * This routine should typically be called for a device that needs to be
 * suspended during the syscore suspend phase. It may also be called during
 * suspend-to-idle to suspend a corresponding CPU device that is attached to a
 * genpd.
 */
void dev_pm_genpd_suspend(struct device *dev)
{
	genpd_switch_state(dev, true);
}
EXPORT_SYMBOL_GPL(dev_pm_genpd_suspend);

/**
 * dev_pm_genpd_resume - Synchronously try to resume the genpd for @dev
 * @dev: The device that is attached to the genpd, which needs to be resumed.
 *
 * This routine should typically be called for a device that needs to be resumed
 * during the syscore resume phase. It may also be called during suspend-to-idle
 * to resume a corresponding CPU device that is attached to a genpd.
 */
void dev_pm_genpd_resume(struct device *dev)
{
	genpd_switch_state(dev, false);
}
EXPORT_SYMBOL_GPL(dev_pm_genpd_resume);

#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,
							   bool has_governor)
{
	struct generic_pm_domain_data *gpd_data;
	struct gpd_timing_data *td;
	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->nb.notifier_call = genpd_dev_pm_qos_notifier;

	/* Allocate data used by a governor. */
	if (has_governor) {
		td = kzalloc(sizeof(*td), GFP_KERNEL);
		if (!td) {
			ret = -ENOMEM;
			goto err_free;
		}

		td->constraint_changed = true;
		td->effective_constraint_ns = PM_QOS_RESUME_LATENCY_NO_CONSTRAINT_NS;
		td->next_wakeup = KTIME_MAX;
		gpd_data->td = td;
	}

	spin_lock_irq(&dev->power.lock);

	if (dev->power.subsys_data->domain_data)
		ret = -EINVAL;
	else
		dev->power.subsys_data->domain_data = &gpd_data->base;

	spin_unlock_irq(&dev->power.lock);

	if (ret)
		goto err_free;

	return gpd_data;

 err_free:
	kfree(gpd_data->td);
	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->td);
	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 genpd_governor_data *gd = genpd->gd;
	struct generic_pm_domain_data *gpd_data;
	int ret;

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

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

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

	gpd_data->hw_mode = genpd->get_hwmode_dev ? genpd->get_hwmode_dev(genpd, dev) : false;

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

	genpd_lock(genpd);

	genpd_set_cpumask(genpd, gpd_data->cpu);

	genpd->device_count++;
	if (gd)
		gd->max_off_time_changed = true;

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

	genpd_unlock(genpd);
	dev_pm_domain_set(dev, &genpd->domain);
 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;

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

	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--;
	if (genpd->gd)
		genpd->gd->max_off_time_changed = true;

	genpd_clear_cpumask(genpd, gpd_data->cpu);

	list_del_init(&pdd->list_node);

	genpd_unlock(genpd);

	dev_pm_domain_set(dev, NULL);

	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);

/**
 * dev_pm_genpd_add_notifier - Add a genpd power on/off notifier for @dev
 *
 * @dev: Device that should be associated with the notifier
 * @nb: The notifier block to register
 *
 * Users may call this function to add a genpd power on/off notifier for an
 * attached @dev. Only one notifier per device is allowed. The notifier is
 * sent when genpd is powering on/off the PM domain.
 *
 * It is assumed that the user 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_add_notifier(struct device *dev, struct notifier_block *nb)
{
	struct generic_pm_domain *genpd;
	struct generic_pm_domain_data *gpd_data;
	int ret;

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

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

	gpd_data = to_gpd_data(dev->power.subsys_data->domain_data);
	if (gpd_data->power_nb)
		return -EEXIST;

	genpd_lock(genpd);
	ret = raw_notifier_chain_register(&genpd->power_notifiers, nb);
	genpd_unlock(genpd);

	if (ret) {
		dev_warn(dev, "failed to add notifier for PM domain %s\n",
			 dev_name(&genpd->dev));
		return ret;
	}

	gpd_data->power_nb = nb;
	return 0;
}
EXPORT_SYMBOL_GPL(dev_pm_genpd_add_notifier);

/**
 * dev_pm_genpd_remove_notifier - Remove a genpd power on/off notifier for @dev
 *
 * @dev: Device that is associated with the notifier
 *
 * Users may call this function to remove a genpd power on/off notifier for an
 * attached @dev.
 *
 * It is assumed that the user 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_remove_notifier(struct device *dev)
{
	struct generic_pm_domain *genpd;
	struct generic_pm_domain_data *gpd_data;
	int ret;

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

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

	gpd_data = to_gpd_data(dev->power.subsys_data->domain_data);
	if (!gpd_data->power_nb)
		return -ENODEV;

	genpd_lock(genpd);
	ret = raw_notifier_chain_unregister(&genpd->power_notifiers,
					    gpd_data->power_nb);
	genpd_unlock(genpd);

	if (ret) {
		dev_warn(dev, "failed to remove notifier for PM domain %s\n",
			 dev_name(&genpd->dev));
		return ret;
	}

	gpd_data->power_nb = NULL;
	return 0;
}
EXPORT_SYMBOL_GPL(dev_pm_genpd_remove_notifier);

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",
		     dev_name(&genpd->dev), 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",
			dev_name(&genpd->dev), 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_provider_release(struct device *dev)
{
	/* nothing to be done here */
}

static int genpd_alloc_data(struct generic_pm_domain *genpd)
{
	struct genpd_governor_data *gd = NULL;
	int ret;

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

	if (genpd->gov) {
		gd = kzalloc(sizeof(*gd), GFP_KERNEL);
		if (!gd) {
			ret = -ENOMEM;
			goto free;
		}

		gd->max_off_time_ns = -1;
		gd->max_off_time_changed = true;
		gd->next_wakeup = KTIME_MAX;
		gd->next_hrtimer = KTIME_MAX;
	}

	/* 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)
			goto free;
	}

	genpd->gd = gd;
	device_initialize(&genpd->dev);
	genpd->dev.release = genpd_provider_release;

	if (!genpd_is_dev_name_fw(genpd)) {
		dev_set_name(&genpd->dev, "%s", genpd->name);
	} else {
		ret = ida_alloc(&genpd_ida, GFP_KERNEL);
		if (ret < 0)
			goto put;

		genpd->device_id = ret;
		dev_set_name(&genpd->dev, "%s_%u", genpd->name, genpd->device_id);
	}

	return 0;
put:
	put_device(&genpd->dev);
	if (genpd->free_states == genpd_free_default_power_state) {
		kfree(genpd->states);
		genpd->states = NULL;
	}
free:
	if (genpd_is_cpu_domain(genpd))
		free_cpumask_var(genpd->cpus);
	kfree(gd);
	return ret;
}

static void genpd_free_data(struct generic_pm_domain *genpd)
{
	put_device(&genpd->dev);
	if (genpd->device_id != -ENXIO)
		ida_free(&genpd_ida, genpd->device_id);
	if (genpd_is_cpu_domain(genpd))
		free_cpumask_var(genpd->cpus);
	if (genpd->free_states)
		genpd->free_states(genpd->states, genpd->state_count);
	kfree(genpd->gd);
}

static void genpd_lock_init(struct generic_pm_domain *genpd)
{
	if (genpd_is_cpu_domain(genpd)) {
		raw_spin_lock_init(&genpd->raw_slock);
		genpd->lock_ops = &genpd_raw_spin_ops;
	} else if (genpd_is_irq_safe(genpd)) {
		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);
	RAW_INIT_NOTIFIER_HEAD(&genpd->power_notifiers);
	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 ? GENPD_STATE_OFF : GENPD_STATE_ON;
	genpd->device_count = 0;
	genpd->provider = NULL;
	genpd->device_id = -ENXIO;
	genpd->has_provider = false;
	genpd->accounting_time = ktime_get_mono_fast_ns();
	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;
	genpd->domain.set_performance_state = genpd_dev_pm_set_performance_state;

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

	/* The always-on governor works better with the corresponding flag. */
	if (gov == &pm_domain_always_on_gov)
		genpd->flags |= GENPD_FLAG_RPM_ALWAYS_ON;

	/* 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)) {
		pr_err("always-on PM domain %s is not on\n", genpd->name);
		return -EINVAL;
	}

	/* Multiple states but no governor doesn't make sense. */
	if (!gov && genpd->state_count > 1)
		pr_warn("%s: no governor for states\n", genpd->name);

	ret = genpd_alloc_data(genpd);
	if (ret)
		return ret;

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

	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", dev_name(&genpd->dev));
		return -EBUSY;
	}

	if (!list_empty(&genpd->parent_links) || genpd->device_count) {
		genpd_unlock(genpd);
		pr_err("%s: unable to remove %s\n", __func__, dev_name(&genpd->dev));
		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);
	genpd_debug_remove(genpd);
	cancel_work_sync(&genpd->power_off_work);
	genpd_free_data(genpd);

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

	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(
					const 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(
					const 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;
	fwnode_dev_initialized(&np->fwnode, true);

	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)
{
	bool ret = false;
	const struct generic_pm_domain *gpd;

	mutex_lock(&gpd_list_lock);
	list_for_each_entry(gpd, &gpd_list, gpd_list_node) {
		if (gpd == genpd) {
			ret = true;
			break;
		}
	}
	mutex_unlock(&gpd_list_lock);

	return ret;
}

/**
 * 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;

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

	if (!genpd_present(genpd))
		return -EINVAL;

	genpd->dev.of_node = np;

	/* Parse genpd OPP table */
	if (!genpd_is_opp_table_fw(genpd) && genpd->set_performance_state) {
		ret = dev_pm_opp_of_add_table(&genpd->dev);
		if (ret)
			return dev_err_probe(&genpd->dev, ret, "Failed to add OPP table\n");

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

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

		return ret;
	}

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

	return 0;
}
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;

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

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

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

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

	return 0;

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

		if (!genpd)
			continue;

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

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

	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 (genpd_is_opp_table_fw(gpd) || !gpd->set_performance_state)
						continue;

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

			fwnode_dev_initialized(&cp->node->fwnode, false);
			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(
					const 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(const struct of_phandle_args *genpdspec, struct device *dev)
{
	struct generic_pm_domain *genpd;
	int ret;

	if (!dev)
		return -EINVAL;

	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(const struct of_phandle_args *parent_spec,
			   const 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 == -ENOENT ? -EPROBE_DEFER : 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(const struct of_phandle_args *parent_spec,
			      const 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
 * @np: Pointer to device node 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 const 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);

	/* Drop the default performance state */
	if (dev_gpd_data(dev)->default_pstate) {
		dev_pm_genpd_set_performance_state(dev, 0);
		dev_gpd_data(dev)->default_pstate = 0;
	}

	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 pstate;
	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)
		return dev_err_probe(dev, ret, "failed to add to PM domain %s\n", pd->name);

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

	/* Set the default performance state */
	pstate = of_get_required_opp_performance_state(dev->of_node, index);
	if (pstate < 0 && pstate != -ENODEV && pstate != -EOPNOTSUPP) {
		ret = pstate;
		goto err;
	} else if (pstate > 0) {
		ret = dev_pm_genpd_set_performance_state(dev, pstate);
		if (ret)
			goto err;
		dev_gpd_data(dev)->default_pstate = pstate;
	}

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

	if (ret) {
		/* Drop the default performance state */
		if (dev_gpd_data(dev)->default_pstate) {
			dev_pm_genpd_set_performance_state(dev, 0);
			dev_gpd_data(dev)->default_pstate = 0;
		}

		genpd_remove_device(pd, dev);
		return -EPROBE_DEFER;
	}

	return 1;

err:
	dev_err(dev, "failed to set required performance state for power-domain %s: %d\n",
		pd->name, ret);
	genpd_remove_device(pd, dev);
	return ret;
}

/**
 * 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 (num_domains < 0 || 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 = 1000LL * residency;

	genpd_state->power_on_latency_ns = 1000LL * exit_latency;
	genpd_state->power_off_latency_ns = 1000LL * 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 (!of_device_is_available(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);

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
/*
 * 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_printf(s, "%-26s  ", p);
}

static void perf_status_str(struct seq_file *s, struct device *dev)
{
	struct generic_pm_domain_data *gpd_data;

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

	seq_printf(s, "%-10u  ", gpd_data->performance_state);
}

static void mode_status_str(struct seq_file *s, struct device *dev)
{
	struct generic_pm_domain_data *gpd_data;

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

	seq_printf(s, "%2s", gpd_data->hw_mode ? "HW" : "SW");
}

static int genpd_summary_one(struct seq_file *s,
			struct generic_pm_domain *genpd)
{
	static const char * const status_lookup[] = {
		[GENPD_STATE_ON] = "on",
		[GENPD_STATE_OFF] = "off"
	};
	struct pm_domain_data *pm_data;
	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  %-30s  %u", dev_name(&genpd->dev), state, genpd->performance_state);

	/*
	 * Modifications on the list require holding locks on both
	 * parent and child, so we are safe.
	 * Also the device name is immutable.
	 */
	list_for_each_entry(link, &genpd->parent_links, parent_node) {
		if (list_is_first(&link->parent_node, &genpd->parent_links))
			seq_printf(s, "\n%48s", " ");
		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) {
		seq_printf(s, "\n    %-30s  ", dev_name(pm_data->dev));
		rtpm_status_str(s, pm_data->dev);
		perf_status_str(s, pm_data->dev);
		mode_status_str(s, pm_data->dev);
	}

	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        performance\n");
	seq_puts(s, "    /device                         runtime status                  managed by\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[] = {
		[GENPD_STATE_ON] = "on",
		[GENPD_STATE_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 == GENPD_STATE_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;
	u64 now, delta, idle_time = 0;
	unsigned int i;
	int ret = 0;

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

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

	for (i = 0; i < genpd->state_count; i++) {
		idle_time += genpd->states[i].idle_time;

		if (genpd->status == GENPD_STATE_OFF && genpd->state_idx == i) {
			now = ktime_get_mono_fast_ns();
			if (now > genpd->accounting_time) {
				delta = now - genpd->accounting_time;
				idle_time += delta;
			}
		}

		do_div(idle_time, NSEC_PER_MSEC);
		seq_printf(s, "S%-13i %-14llu %-14llu %llu\n", i, idle_time,
			   genpd->states[i].usage, genpd->states[i].rejected);
	}

	genpd_unlock(genpd);
	return ret;
}

static int active_time_show(struct seq_file *s, void *data)
{
	struct generic_pm_domain *genpd = s->private;
	u64 now, on_time, delta = 0;
	int ret = 0;

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

	if (genpd->status == GENPD_STATE_ON) {
		now = ktime_get_mono_fast_ns();
		if (now > genpd->accounting_time)
			delta = now - genpd->accounting_time;
	}

	on_time = genpd->on_time + delta;
	do_div(on_time, NSEC_PER_MSEC);
	seq_printf(s, "%llu ms\n", on_time);

	genpd_unlock(genpd);
	return ret;
}

static int total_idle_time_show(struct seq_file *s, void *data)
{
	struct generic_pm_domain *genpd = s->private;
	u64 now, delta, 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++) {
		total += genpd->states[i].idle_time;

		if (genpd->status == GENPD_STATE_OFF && genpd->state_idx == i) {
			now = ktime_get_mono_fast_ns();
			if (now > genpd->accounting_time) {
				delta = now - genpd->accounting_time;
				total += delta;
			}
		}
	}

	do_div(total, NSEC_PER_MSEC);
	seq_printf(s, "%llu ms\n", 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;
	int ret = 0;

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

	list_for_each_entry(pm_data, &genpd->dev_list, list_node)
		seq_printf(s, "%s\n", dev_name(pm_data->dev));

	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 void genpd_debug_add(struct generic_pm_domain *genpd)
{
	struct dentry *d;

	if (!genpd_debugfs_dir)
		return;

	d = debugfs_create_dir(dev_name(&genpd->dev), 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);
}

static int __init genpd_debug_init(void)
{
	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)
		genpd_debug_add(genpd);

	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 */