Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 3423 insertions, 0 deletions

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
new file mode 100644
index 0000000000..5cb2023581
--- /dev/null
+++ b/drivers/base/power/domain.c
@@ -0,0 +1,3423 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * drivers/base/power/domain.c - Common code related to device power domains.
+ *
+ * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
+ */
+#define pr_fmt(fmt) "PM: " fmt
+
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/io.h>
+#include <linux/platform_device.h>
+#include <linux/pm_opp.h>
+#include <linux/pm_runtime.h>
+#include <linux/pm_domain.h>
+#include <linux/pm_qos.h>
+#include <linux/pm_clock.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/sched.h>
+#include <linux/suspend.h>
+#include <linux/export.h>
+#include <linux/cpu.h>
+#include <linux/debugfs.h>
+
+#include "power.h"
+
+#define GENPD_RETRY_MAX_MS	250		/* Approximate */
+
+#define GENPD_DEV_CALLBACK(genpd, type, callback, dev)		\
+({								\
+	type (*__routine)(struct device *__d); 			\
+	type __ret = (type)0;					\
+								\
+	__routine = genpd->dev_ops.callback; 			\
+	if (__routine) {					\
+		__ret = __routine(dev); 			\
+	}							\
+	__ret;							\
+})
+
+static LIST_HEAD(gpd_list);
+static DEFINE_MUTEX(gpd_list_lock);
+
+struct genpd_lock_ops {
+	void (*lock)(struct generic_pm_domain *genpd);
+	void (*lock_nested)(struct generic_pm_domain *genpd, int depth);
+	int (*lock_interruptible)(struct generic_pm_domain *genpd);
+	void (*unlock)(struct generic_pm_domain *genpd);
+};
+
+static void genpd_lock_mtx(struct generic_pm_domain *genpd)
+{
+	mutex_lock(&genpd->mlock);
+}
+
+static void genpd_lock_nested_mtx(struct generic_pm_domain *genpd,
+					int depth)
+{
+	mutex_lock_nested(&genpd->mlock, depth);
+}
+
+static int genpd_lock_interruptible_mtx(struct generic_pm_domain *genpd)
+{
+	return mutex_lock_interruptible(&genpd->mlock);
+}
+
+static void genpd_unlock_mtx(struct generic_pm_domain *genpd)
+{
+	return mutex_unlock(&genpd->mlock);
+}
+
+static const struct genpd_lock_ops genpd_mtx_ops = {
+	.lock = genpd_lock_mtx,
+	.lock_nested = genpd_lock_nested_mtx,
+	.lock_interruptible = genpd_lock_interruptible_mtx,
+	.unlock = genpd_unlock_mtx,
+};
+
+static void genpd_lock_spin(struct generic_pm_domain *genpd)
+	__acquires(&genpd->slock)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&genpd->slock, flags);
+	genpd->lock_flags = flags;
+}
+
+static void genpd_lock_nested_spin(struct generic_pm_domain *genpd,
+					int depth)
+	__acquires(&genpd->slock)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave_nested(&genpd->slock, flags, depth);
+	genpd->lock_flags = flags;
+}
+
+static int genpd_lock_interruptible_spin(struct generic_pm_domain *genpd)
+	__acquires(&genpd->slock)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&genpd->slock, flags);
+	genpd->lock_flags = flags;
+	return 0;
+}
+
+static void genpd_unlock_spin(struct generic_pm_domain *genpd)
+	__releases(&genpd->slock)
+{
+	spin_unlock_irqrestore(&genpd->slock, genpd->lock_flags);
+}
+
+static const struct genpd_lock_ops genpd_spin_ops = {
+	.lock = genpd_lock_spin,
+	.lock_nested = genpd_lock_nested_spin,
+	.lock_interruptible = genpd_lock_interruptible_spin,
+	.unlock = genpd_unlock_spin,
+};
+
+#define genpd_lock(p)			p->lock_ops->lock(p)
+#define genpd_lock_nested(p, d)		p->lock_ops->lock_nested(p, d)
+#define genpd_lock_interruptible(p)	p->lock_ops->lock_interruptible(p)
+#define genpd_unlock(p)			p->lock_ops->unlock(p)
+
+#define genpd_status_on(genpd)		(genpd->status == 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)
+
+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",
+				genpd->name);
+
+	return ret;
+}
+
+static int genpd_runtime_suspend(struct device *dev);
+
+/*
+ * Get the generic PM domain for a particular struct device.
+ * This validates the struct device pointer, the PM domain pointer,
+ * and checks that the PM domain pointer is a real generic PM domain.
+ * Any failure results in NULL being returned.
+ */
+static struct generic_pm_domain *dev_to_genpd_safe(struct device *dev)
+{
+	if (IS_ERR_OR_NULL(dev) || IS_ERR_OR_NULL(dev->pm_domain))
+		return NULL;
+
+	/* A genpd's always have its ->runtime_suspend() callback assigned. */
+	if (dev->pm_domain->ops.runtime_suspend == genpd_runtime_suspend)
+		return pd_to_genpd(dev->pm_domain);
+
+	return NULL;
+}
+
+/*
+ * This should only be used where we are certain that the pm_domain
+ * attached to the device is a genpd domain.
+ */
+static struct generic_pm_domain *dev_to_genpd(struct device *dev)
+{
+	if (IS_ERR_OR_NULL(dev->pm_domain))
+		return ERR_PTR(-EINVAL);
+
+	return pd_to_genpd(dev->pm_domain);
+}
+
+static int genpd_stop_dev(const struct generic_pm_domain *genpd,
+			  struct device *dev)
+{
+	return GENPD_DEV_CALLBACK(genpd, int, stop, dev);
+}
+
+static int genpd_start_dev(const struct generic_pm_domain *genpd,
+			   struct device *dev)
+{
+	return GENPD_DEV_CALLBACK(genpd, int, start, dev);
+}
+
+static bool genpd_sd_counter_dec(struct generic_pm_domain *genpd)
+{
+	bool ret = false;
+
+	if (!WARN_ON(atomic_read(&genpd->sd_count) == 0))
+		ret = !!atomic_dec_and_test(&genpd->sd_count);
+
+	return ret;
+}
+
+static void genpd_sd_counter_inc(struct generic_pm_domain *genpd)
+{
+	atomic_inc(&genpd->sd_count);
+	smp_mb__after_atomic();
+}
+
+#ifdef CONFIG_DEBUG_FS
+static 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(genpd->name, 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)
+{
+	struct generic_pm_domain *parent;
+	struct gpd_link *link;
+	int parent_state, ret;
+
+	if (state == genpd->performance_state)
+		return 0;
+
+	/* Propagate to parents of genpd */
+	list_for_each_entry(link, &genpd->child_links, child_node) {
+		parent = link->parent;
+
+		/* Find parent's performance state */
+		ret = genpd_xlate_performance_state(genpd, parent, state);
+		if (unlikely(ret < 0))
+			goto err;
+
+		parent_state = ret;
+
+		genpd_lock_nested(parent, depth + 1);
+
+		link->prev_performance_state = link->performance_state;
+		link->performance_state = parent_state;
+		parent_state = _genpd_reeval_performance_state(parent,
+						parent_state);
+		ret = _genpd_set_performance_state(parent, parent_state, depth + 1);
+		if (ret)
+			link->performance_state = link->prev_performance_state;
+
+		genpd_unlock(parent);
+
+		if (ret)
+			goto err;
+	}
+
+	if (genpd->set_performance_state) {
+		ret = genpd->set_performance_state(genpd, state);
+		if (ret)
+			goto err;
+	}
+
+	genpd->performance_state = state;
+	return 0;
+
+err:
+	/* Encountered an error, lets rollback */
+	list_for_each_entry_continue_reverse(link, &genpd->child_links,
+					     child_node) {
+		parent = link->parent;
+
+		genpd_lock_nested(parent, depth + 1);
+
+		parent_state = link->prev_performance_state;
+		link->performance_state = parent_state;
+
+		parent_state = _genpd_reeval_performance_state(parent,
+						parent_state);
+		if (_genpd_set_performance_state(parent, parent_state, depth + 1)) {
+			pr_err("%s: Failed to roll back to %d performance state\n",
+			       parent->name, parent_state);
+		}
+
+		genpd_unlock(parent);
+	}
+
+	return ret;
+}
+
+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);
+}
+
+/**
+ * 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;
+	int ret = 0;
+
+	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;
+
+	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;
+}
+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);
+
+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",
+		 genpd->name, "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",
+		 genpd->name, "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++;
+	}
+
+	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;
+	}
+
+	mutex_lock(&gpd_list_lock);
+
+	list_for_each_entry(genpd, &gpd_list, gpd_list_node)
+		genpd_queue_power_off_work(genpd);
+
+	mutex_unlock(&gpd_list_lock);
+
+	return 0;
+}
+late_initcall(genpd_power_off_unused);
+
+#ifdef CONFIG_PM_SLEEP
+
+/**
+ * genpd_sync_power_off - Synchronously power off a PM domain and its parents.
+ * @genpd: PM domain to power off, if possible.
+ * @use_lock: use the lock.
+ * @depth: nesting count for lockdep.
+ *
+ * Check if the given PM domain can be powered off (during system suspend or
+ * hibernation) and do that if so.  Also, in that case propagate to its parents.
+ *
+ * This function is only called in "noirq" and "syscore" stages of system power
+ * transitions. The "noirq" callbacks may be executed asynchronously, thus in
+ * these cases the lock must be held.
+ */
+static void genpd_sync_power_off(struct generic_pm_domain *genpd, bool use_lock,
+				 unsigned int depth)
+{
+	struct gpd_link *link;
+
+	if (!genpd_status_on(genpd) || genpd_is_always_on(genpd))
+		return;
+
+	if (genpd->suspended_count != genpd->device_count
+	    || atomic_read(&genpd->sd_count) > 0)
+		return;
+
+	/* 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))
+		return;
+
+	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);
+
+	if (genpd->prepared_count++ == 0)
+		genpd->suspended_count = 0;
+
+	genpd_unlock(genpd);
+
+	ret = pm_generic_prepare(dev);
+	if (ret < 0) {
+		genpd_lock(genpd);
+
+		genpd->prepared_count--;
+
+		genpd_unlock(genpd);
+	}
+
+	/* Never return 1, as genpd don't cope with the direct_complete path. */
+	return ret >= 0 ? 0 : ret;
+}
+
+/**
+ * genpd_finish_suspend - Completion of suspend or hibernation of device in an
+ *   I/O pm domain.
+ * @dev: Device to suspend.
+ * @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);
+
+	ret = genpd->attach_dev ? genpd->attach_dev(genpd, dev) : 0;
+	if (ret)
+		goto out;
+
+	genpd_lock(genpd);
+
+	genpd_set_cpumask(genpd, gpd_data->cpu);
+	dev_pm_domain_set(dev, &genpd->domain);
+
+	genpd->device_count++;
+	if (gd)
+		gd->max_off_time_changed = true;
+
+	list_add_tail(&gpd_data->base.list_node, &genpd->dev_list);
+
+	genpd_unlock(genpd);
+ out:
+	if (ret)
+		genpd_free_dev_data(dev, gpd_data);
+	else
+		dev_pm_qos_add_notifier(dev, &gpd_data->nb,
+					DEV_PM_QOS_RESUME_LATENCY);
+
+	return ret;
+}
+
+/**
+ * pm_genpd_add_device - Add a device to an I/O PM domain.
+ * @genpd: PM domain to add the device to.
+ * @dev: Device to be added.
+ */
+int pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev)
+{
+	int ret;
+
+	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);
+	dev_pm_domain_set(dev, NULL);
+
+	list_del_init(&pdd->list_node);
+
+	genpd_unlock(genpd);
+
+	if (genpd->detach_dev)
+		genpd->detach_dev(genpd, dev);
+
+	genpd_free_dev_data(dev, gpd_data);
+
+	return 0;
+
+ out:
+	genpd_unlock(genpd);
+	dev_pm_qos_add_notifier(dev, &gpd_data->nb, DEV_PM_QOS_RESUME_LATENCY);
+
+	return ret;
+}
+
+/**
+ * pm_genpd_remove_device - Remove a device from an I/O PM domain.
+ * @dev: Device to be removed.
+ */
+int pm_genpd_remove_device(struct device *dev)
+{
+	struct generic_pm_domain *genpd = dev_to_genpd_safe(dev);
+
+	if (!genpd)
+		return -EINVAL;
+
+	return genpd_remove_device(genpd, dev);
+}
+EXPORT_SYMBOL_GPL(pm_genpd_remove_device);
+
+/**
+ * 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",
+			 genpd->name);
+		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",
+			 genpd->name);
+		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",
+				genpd->name, subdomain->name);
+		return -EINVAL;
+	}
+
+	link = kzalloc(sizeof(*link), GFP_KERNEL);
+	if (!link)
+		return -ENOMEM;
+
+	genpd_lock(subdomain);
+	genpd_lock_nested(genpd, SINGLE_DEPTH_NESTING);
+
+	if (!genpd_status_on(genpd) && genpd_status_on(subdomain)) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	list_for_each_entry(itr, &genpd->parent_links, parent_node) {
+		if (itr->child == subdomain && itr->parent == genpd) {
+			ret = -EINVAL;
+			goto out;
+		}
+	}
+
+	link->parent = genpd;
+	list_add_tail(&link->parent_node, &genpd->parent_links);
+	link->child = subdomain;
+	list_add_tail(&link->child_node, &subdomain->child_links);
+	if (genpd_status_on(subdomain))
+		genpd_sd_counter_inc(genpd);
+
+ out:
+	genpd_unlock(genpd);
+	genpd_unlock(subdomain);
+	if (ret)
+		kfree(link);
+	return ret;
+}
+
+/**
+ * pm_genpd_add_subdomain - Add a subdomain to an I/O PM domain.
+ * @genpd: Leader PM domain to add the subdomain to.
+ * @subdomain: Subdomain to be added.
+ */
+int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
+			   struct generic_pm_domain *subdomain)
+{
+	int ret;
+
+	mutex_lock(&gpd_list_lock);
+	ret = genpd_add_subdomain(genpd, subdomain);
+	mutex_unlock(&gpd_list_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pm_genpd_add_subdomain);
+
+/**
+ * pm_genpd_remove_subdomain - Remove a subdomain from an I/O PM domain.
+ * @genpd: Leader PM domain to remove the subdomain from.
+ * @subdomain: Subdomain to be removed.
+ */
+int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
+			      struct generic_pm_domain *subdomain)
+{
+	struct gpd_link *l, *link;
+	int ret = -EINVAL;
+
+	if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(subdomain))
+		return -EINVAL;
+
+	genpd_lock(subdomain);
+	genpd_lock_nested(genpd, SINGLE_DEPTH_NESTING);
+
+	if (!list_empty(&subdomain->parent_links) || subdomain->device_count) {
+		pr_warn("%s: unable to remove subdomain %s\n",
+			genpd->name, subdomain->name);
+		ret = -EBUSY;
+		goto out;
+	}
+
+	list_for_each_entry_safe(link, l, &genpd->parent_links, parent_node) {
+		if (link->child != subdomain)
+			continue;
+
+		list_del(&link->parent_node);
+		list_del(&link->child_node);
+		kfree(link);
+		if (genpd_status_on(subdomain))
+			genpd_sd_counter_dec(genpd);
+
+		ret = 0;
+		break;
+	}
+
+out:
+	genpd_unlock(genpd);
+	genpd_unlock(subdomain);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pm_genpd_remove_subdomain);
+
+static void genpd_free_default_power_state(struct genpd_power_state *states,
+					   unsigned int state_count)
+{
+	kfree(states);
+}
+
+static int genpd_set_default_power_state(struct generic_pm_domain *genpd)
+{
+	struct genpd_power_state *state;
+
+	state = kzalloc(sizeof(*state), GFP_KERNEL);
+	if (!state)
+		return -ENOMEM;
+
+	genpd->states = state;
+	genpd->state_count = 1;
+	genpd->free_states = genpd_free_default_power_state;
+
+	return 0;
+}
+
+static 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;
+	return 0;
+
+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)
+{
+	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->flags & GENPD_FLAG_IRQ_SAFE) {
+		spin_lock_init(&genpd->slock);
+		genpd->lock_ops = &genpd_spin_ops;
+	} else {
+		mutex_init(&genpd->mlock);
+		genpd->lock_ops = &genpd_mtx_ops;
+	}
+}
+
+/**
+ * pm_genpd_init - Initialize a generic I/O PM domain object.
+ * @genpd: PM domain object to initialize.
+ * @gov: PM domain governor to associate with the domain (may be NULL).
+ * @is_off: Initial value of the domain's power_is_off field.
+ *
+ * Returns 0 on successful initialization, else a negative error code.
+ */
+int pm_genpd_init(struct generic_pm_domain *genpd,
+		  struct dev_power_governor *gov, bool is_off)
+{
+	int ret;
+
+	if (IS_ERR_OR_NULL(genpd))
+		return -EINVAL;
+
+	INIT_LIST_HEAD(&genpd->parent_links);
+	INIT_LIST_HEAD(&genpd->child_links);
+	INIT_LIST_HEAD(&genpd->dev_list);
+	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->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;
+
+	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;
+
+	device_initialize(&genpd->dev);
+	dev_set_name(&genpd->dev, "%s", genpd->name);
+
+	mutex_lock(&gpd_list_lock);
+	list_add(&genpd->gpd_list_node, &gpd_list);
+	mutex_unlock(&gpd_list_lock);
+	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", genpd->name);
+		return -EBUSY;
+	}
+
+	if (!list_empty(&genpd->parent_links) || genpd->device_count) {
+		genpd_unlock(genpd);
+		pr_err("%s: unable to remove %s\n", __func__, genpd->name);
+		return -EBUSY;
+	}
+
+	list_for_each_entry_safe(link, l, &genpd->child_links, child_node) {
+		list_del(&link->parent_node);
+		list_del(&link->child_node);
+		kfree(link);
+	}
+
+	list_del(&genpd->gpd_list_node);
+	genpd_unlock(genpd);
+	genpd_debug_remove(genpd);
+	cancel_work_sync(&genpd->power_off_work);
+	genpd_free_data(genpd);
+
+	pr_debug("%s: removed %s\n", __func__, genpd->name);
+
+	return 0;
+}
+
+/**
+ * pm_genpd_remove - Remove a generic I/O PM domain
+ * @genpd: Pointer to PM domain that is to be removed.
+ *
+ * To remove the PM domain, this function:
+ *  - Removes the PM domain as a subdomain to any parent domains,
+ *    if it was added.
+ *  - Removes the PM domain from the list of registered PM domains.
+ *
+ * The PM domain will only be removed, if the associated provider has
+ * been removed, it is not a parent to any other PM domain and has no
+ * devices associated with it.
+ */
+int pm_genpd_remove(struct generic_pm_domain *genpd)
+{
+	int ret;
+
+	mutex_lock(&gpd_list_lock);
+	ret = genpd_remove(genpd);
+	mutex_unlock(&gpd_list_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pm_genpd_remove);
+
+#ifdef CONFIG_PM_GENERIC_DOMAINS_OF
+
+/*
+ * Device Tree based PM domain providers.
+ *
+ * The code below implements generic device tree based PM domain providers that
+ * bind device tree nodes with generic PM domains registered in the system.
+ *
+ * Any driver that registers generic PM domains and needs to support binding of
+ * devices to these domains is supposed to register a PM domain provider, which
+ * maps a PM domain specifier retrieved from the device tree to a PM domain.
+ *
+ * Two simple mapping functions have been provided for convenience:
+ *  - genpd_xlate_simple() for 1:1 device tree node to PM domain mapping.
+ *  - genpd_xlate_onecell() for mapping of multiple PM domains per node by
+ *    index.
+ */
+
+/**
+ * struct of_genpd_provider - PM domain provider registration structure
+ * @link: Entry in global list of PM domain providers
+ * @node: Pointer to device tree node of PM domain provider
+ * @xlate: Provider-specific xlate callback mapping a set of specifier cells
+ *         into a PM domain.
+ * @data: context pointer to be passed into @xlate callback
+ */
+struct of_genpd_provider {
+	struct list_head link;
+	struct device_node *node;
+	genpd_xlate_t xlate;
+	void *data;
+};
+
+/* List of registered PM domain providers. */
+static LIST_HEAD(of_genpd_providers);
+/* Mutex to protect the list above. */
+static DEFINE_MUTEX(of_genpd_mutex);
+
+/**
+ * genpd_xlate_simple() - Xlate function for direct node-domain mapping
+ * @genpdspec: OF phandle args to map into a PM domain
+ * @data: xlate function private data - pointer to struct generic_pm_domain
+ *
+ * This is a generic xlate function that can be used to model PM domains that
+ * have their own device tree nodes. The private data of xlate function needs
+ * to be a valid pointer to struct generic_pm_domain.
+ */
+static struct generic_pm_domain *genpd_xlate_simple(
+					struct of_phandle_args *genpdspec,
+					void *data)
+{
+	return data;
+}
+
+/**
+ * genpd_xlate_onecell() - Xlate function using a single index.
+ * @genpdspec: OF phandle args to map into a PM domain
+ * @data: xlate function private data - pointer to struct genpd_onecell_data
+ *
+ * This is a generic xlate function that can be used to model simple PM domain
+ * controllers that have one device tree node and provide multiple PM domains.
+ * A single cell is used as an index into an array of PM domains specified in
+ * the genpd_onecell_data struct when registering the provider.
+ */
+static struct generic_pm_domain *genpd_xlate_onecell(
+					struct of_phandle_args *genpdspec,
+					void *data)
+{
+	struct genpd_onecell_data *genpd_data = data;
+	unsigned int idx = genpdspec->args[0];
+
+	if (genpdspec->args_count != 1)
+		return ERR_PTR(-EINVAL);
+
+	if (idx >= genpd_data->num_domains) {
+		pr_err("%s: invalid domain index %u\n", __func__, idx);
+		return ERR_PTR(-EINVAL);
+	}
+
+	if (!genpd_data->domains[idx])
+		return ERR_PTR(-ENOENT);
+
+	return genpd_data->domains[idx];
+}
+
+/**
+ * genpd_add_provider() - Register a PM domain provider for a node
+ * @np: Device node pointer associated with the PM domain provider.
+ * @xlate: Callback for decoding PM domain from phandle arguments.
+ * @data: Context pointer for @xlate callback.
+ */
+static int genpd_add_provider(struct device_node *np, genpd_xlate_t xlate,
+			      void *data)
+{
+	struct of_genpd_provider *cp;
+
+	cp = kzalloc(sizeof(*cp), GFP_KERNEL);
+	if (!cp)
+		return -ENOMEM;
+
+	cp->node = of_node_get(np);
+	cp->data = data;
+	cp->xlate = xlate;
+	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->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->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->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->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 (!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(
+					struct of_phandle_args *genpdspec)
+{
+	struct generic_pm_domain *genpd = ERR_PTR(-ENOENT);
+	struct of_genpd_provider *provider;
+
+	if (!genpdspec)
+		return ERR_PTR(-EINVAL);
+
+	mutex_lock(&of_genpd_mutex);
+
+	/* Check if we have such a provider in our array */
+	list_for_each_entry(provider, &of_genpd_providers, link) {
+		if (provider->node == genpdspec->np)
+			genpd = provider->xlate(genpdspec, provider->data);
+		if (!IS_ERR(genpd))
+			break;
+	}
+
+	mutex_unlock(&of_genpd_mutex);
+
+	return genpd;
+}
+
+/**
+ * of_genpd_add_device() - Add a device to an I/O PM domain
+ * @genpdspec: OF phandle args to use for look-up PM domain
+ * @dev: Device to be added.
+ *
+ * Looks-up an I/O PM domain based upon phandle args provided and adds
+ * the device to the PM domain. Returns a negative error code on failure.
+ */
+int of_genpd_add_device(struct of_phandle_args *genpdspec, struct device *dev)
+{
+	struct generic_pm_domain *genpd;
+	int ret;
+
+	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(struct of_phandle_args *parent_spec,
+			   struct of_phandle_args *subdomain_spec)
+{
+	struct generic_pm_domain *parent, *subdomain;
+	int ret;
+
+	mutex_lock(&gpd_list_lock);
+
+	parent = genpd_get_from_provider(parent_spec);
+	if (IS_ERR(parent)) {
+		ret = PTR_ERR(parent);
+		goto out;
+	}
+
+	subdomain = genpd_get_from_provider(subdomain_spec);
+	if (IS_ERR(subdomain)) {
+		ret = PTR_ERR(subdomain);
+		goto out;
+	}
+
+	ret = genpd_add_subdomain(parent, subdomain);
+
+out:
+	mutex_unlock(&gpd_list_lock);
+
+	return ret == -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(struct of_phandle_args *parent_spec,
+			      struct of_phandle_args *subdomain_spec)
+{
+	struct generic_pm_domain *parent, *subdomain;
+	int ret;
+
+	mutex_lock(&gpd_list_lock);
+
+	parent = genpd_get_from_provider(parent_spec);
+	if (IS_ERR(parent)) {
+		ret = PTR_ERR(parent);
+		goto out;
+	}
+
+	subdomain = genpd_get_from_provider(subdomain_spec);
+	if (IS_ERR(subdomain)) {
+		ret = PTR_ERR(subdomain);
+		goto out;
+	}
+
+	ret = pm_genpd_remove_subdomain(parent, subdomain);
+
+out:
+	mutex_unlock(&gpd_list_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(of_genpd_remove_subdomain);
+
+/**
+ * of_genpd_remove_last - Remove the last PM domain registered for a provider
+ * @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 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 (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);
+
+/**
+ * pm_genpd_opp_to_performance_state - Gets performance state of the genpd from its OPP node.
+ *
+ * @genpd_dev: Genpd's device for which the performance-state needs to be found.
+ * @opp: struct dev_pm_opp of the OPP for which we need to find performance
+ *	state.
+ *
+ * Returns performance state encoded in the OPP of the genpd. This calls
+ * platform specific genpd->opp_to_performance_state() callback to translate
+ * power domain OPP to performance state.
+ *
+ * Returns performance state on success and 0 on failure.
+ */
+unsigned int pm_genpd_opp_to_performance_state(struct device *genpd_dev,
+					       struct dev_pm_opp *opp)
+{
+	struct generic_pm_domain *genpd = NULL;
+	int state;
+
+	genpd = container_of(genpd_dev, struct generic_pm_domain, dev);
+
+	if (unlikely(!genpd->opp_to_performance_state))
+		return 0;
+
+	genpd_lock(genpd);
+	state = genpd->opp_to_performance_state(genpd, opp);
+	genpd_unlock(genpd);
+
+	return state;
+}
+EXPORT_SYMBOL_GPL(pm_genpd_opp_to_performance_state);
+
+static int __init genpd_bus_init(void)
+{
+	return bus_register(&genpd_bus_type);
+}
+core_initcall(genpd_bus_init);
+
+#endif /* CONFIG_PM_GENERIC_DOMAINS_OF */
+
+
+/***        debugfs support        ***/
+
+#ifdef CONFIG_DEBUG_FS
+/*
+ * 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, "%-25s  ", 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_put_decimal_ull(s, "", gpd_data->performance_state);
+}
+
+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;
+	const char *kobj_path;
+	struct gpd_link *link;
+	char state[16];
+	int ret;
+
+	ret = genpd_lock_interruptible(genpd);
+	if (ret)
+		return -ERESTARTSYS;
+
+	if (WARN_ON(genpd->status >= ARRAY_SIZE(status_lookup)))
+		goto exit;
+	if (!genpd_status_on(genpd))
+		snprintf(state, sizeof(state), "%s-%u",
+			 status_lookup[genpd->status], genpd->state_idx);
+	else
+		snprintf(state, sizeof(state), "%s",
+			 status_lookup[genpd->status]);
+	seq_printf(s, "%-30s  %-50s %u", genpd->name, state, genpd->performance_state);
+
+	/*
+	 * Modifications on the list require holding locks on both
+	 * parent and child, so we are safe.
+	 * Also genpd->name is immutable.
+	 */
+	list_for_each_entry(link, &genpd->parent_links, parent_node) {
+		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) {
+		kobj_path = kobject_get_path(&pm_data->dev->kobj,
+				genpd_is_irq_safe(genpd) ?
+				GFP_ATOMIC : GFP_KERNEL);
+		if (kobj_path == NULL)
+			continue;
+
+		seq_printf(s, "\n    %-50s  ", kobj_path);
+		rtpm_status_str(s, pm_data->dev);
+		perf_status_str(s, pm_data->dev);
+		kfree(kobj_path);
+	}
+
+	seq_puts(s, "\n");
+exit:
+	genpd_unlock(genpd);
+
+	return 0;
+}
+
+static int summary_show(struct seq_file *s, void *data)
+{
+	struct generic_pm_domain *genpd;
+	int ret = 0;
+
+	seq_puts(s, "domain                          status          children                           performance\n");
+	seq_puts(s, "    /device                                             runtime status\n");
+	seq_puts(s, "----------------------------------------------------------------------------------------------\n");
+
+	ret = mutex_lock_interruptible(&gpd_list_lock);
+	if (ret)
+		return -ERESTARTSYS;
+
+	list_for_each_entry(genpd, &gpd_list, gpd_list_node) {
+		ret = genpd_summary_one(s, genpd);
+		if (ret)
+			break;
+	}
+	mutex_unlock(&gpd_list_lock);
+
+	return ret;
+}
+
+static int status_show(struct seq_file *s, void *data)
+{
+	static const char * const status_lookup[] = {
+		[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;
+	const char *kobj_path;
+	int ret = 0;
+
+	ret = genpd_lock_interruptible(genpd);
+	if (ret)
+		return -ERESTARTSYS;
+
+	list_for_each_entry(pm_data, &genpd->dev_list, list_node) {
+		kobj_path = kobject_get_path(&pm_data->dev->kobj,
+				genpd_is_irq_safe(genpd) ?
+				GFP_ATOMIC : GFP_KERNEL);
+		if (kobj_path == NULL)
+			continue;
+
+		seq_printf(s, "%s\n", kobj_path);
+		kfree(kobj_path);
+	}
+
+	genpd_unlock(genpd);
+	return ret;
+}
+
+static int perf_state_show(struct seq_file *s, void *data)
+{
+	struct generic_pm_domain *genpd = s->private;
+
+	if (genpd_lock_interruptible(genpd))
+		return -ERESTARTSYS;
+
+	seq_printf(s, "%u\n", genpd->performance_state);
+
+	genpd_unlock(genpd);
+	return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(summary);
+DEFINE_SHOW_ATTRIBUTE(status);
+DEFINE_SHOW_ATTRIBUTE(sub_domains);
+DEFINE_SHOW_ATTRIBUTE(idle_states);
+DEFINE_SHOW_ATTRIBUTE(active_time);
+DEFINE_SHOW_ATTRIBUTE(total_idle_time);
+DEFINE_SHOW_ATTRIBUTE(devices);
+DEFINE_SHOW_ATTRIBUTE(perf_state);
+
+static void genpd_debug_add(struct generic_pm_domain *genpd)
+{
+	struct dentry *d;
+
+	if (!genpd_debugfs_dir)
+		return;
+
+	d = debugfs_create_dir(genpd->name, genpd_debugfs_dir);
+
+	debugfs_create_file("current_state", 0444,
+			    d, genpd, &status_fops);
+	debugfs_create_file("sub_domains", 0444,
+			    d, genpd, &sub_domains_fops);
+	debugfs_create_file("idle_states", 0444,
+			    d, genpd, &idle_states_fops);
+	debugfs_create_file("active_time", 0444,
+			    d, genpd, &active_time_fops);
+	debugfs_create_file("total_idle_time", 0444,
+			    d, genpd, &total_idle_time_fops);
+	debugfs_create_file("devices", 0444,
+			    d, genpd, &devices_fops);
+	if (genpd->set_performance_state)
+		debugfs_create_file("perf_state", 0444,
+				    d, genpd, &perf_state_fops);
+}
+
+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 */