PM: domains: Move genpd and its governor to the pmdomain subsystem

It seems reasonable to collect the core parts for the generic PM domain,
along with its corresponding provider drivers. Therefore let's move the
files from drivers/base/power/ to drivers/pmdomain/ and while at it, let's
also rename the files accordingly.

Moreover, let's also update MAINTAINERS to reflect the update.

Cc: Kevin Hilman <khilman@kernel.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20231213113305.29098-1-ulf.hansson@linaro.org

1 files changed, 3399 insertions, 0 deletions

diff --git a/drivers/pmdomain/core.c b/drivers/pmdomain/core.c
new file mode 100644
index 000000000000..9ee1bf2ece10
--- /dev/null
+++ b/drivers/pmdomain/core.c
@@ -0,0 +1,3399 @@
+// 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>
+
+#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)
+#define genpd_is_opp_table_fw(genpd)	(genpd->flags & GENPD_FLAG_OPP_TABLE_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",
+				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);
+}
+
+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);
+
+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;
+	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;
+
+	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_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(
+					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);
+
+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 */