/*
   * drivers/base/power/domain.c - Common code related to device power domains.
   *
   * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
   *
   * This file is released under the GPLv2.
   */
  
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/io.h>
  #include <linux/pm_runtime.h>
  #include <linux/pm_domain.h>
  #include <linux/slab.h>
  #include <linux/err.h>

  #include <linux/sched.h>
  #include <linux/suspend.h>

  #include <linux/export.h>
  
  #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); 			\
  	} else {						\
  		__routine = dev_gpd_data(dev)->ops.callback;	\
  		if (__routine) 					\
  			__ret = __routine(dev);			\
  	}							\
  	__ret;							\
  })

  #define GENPD_DEV_TIMED_CALLBACK(genpd, type, callback, dev, field, name)	\
  ({										\
  	ktime_t __start = ktime_get();						\
  	type __retval = GENPD_DEV_CALLBACK(genpd, type, callback, dev);		\
  	s64 __elapsed = ktime_to_ns(ktime_sub(ktime_get(), __start));		\
  	struct generic_pm_domain_data *__gpd_data = dev_gpd_data(dev);		\
  	if (__elapsed > __gpd_data->td.field) {					\
  		__gpd_data->td.field = __elapsed;				\
  		dev_warn(dev, name " latency exceeded, new value %lld ns
  ",	\
  			__elapsed);						\
  	}									\
  	__retval;								\
  })

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

  #ifdef CONFIG_PM

  struct generic_pm_domain *dev_to_genpd(struct device *dev)

  {
  	if (IS_ERR_OR_NULL(dev->pm_domain))
  		return ERR_PTR(-EINVAL);

  	return pd_to_genpd(dev->pm_domain);

  }

  static int genpd_stop_dev(struct generic_pm_domain *genpd, struct device *dev)
  {

  	return GENPD_DEV_TIMED_CALLBACK(genpd, int, stop, dev,
  					stop_latency_ns, "stop");

  }
  
  static int genpd_start_dev(struct generic_pm_domain *genpd, struct device *dev)
  {

  	return GENPD_DEV_TIMED_CALLBACK(genpd, int, start, dev,
  					start_latency_ns, "start");

  }

  static int genpd_save_dev(struct generic_pm_domain *genpd, struct device *dev)
  {

  	return GENPD_DEV_TIMED_CALLBACK(genpd, int, save_state, dev,
  					save_state_latency_ns, "state save");

  }
  
  static int genpd_restore_dev(struct generic_pm_domain *genpd, struct device *dev)
  {

  	return GENPD_DEV_TIMED_CALLBACK(genpd, int, restore_state, dev,
  					restore_state_latency_ns,
  					"state restore");

  }

  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_inc();

  }

  static void genpd_acquire_lock(struct generic_pm_domain *genpd)
  {
  	DEFINE_WAIT(wait);
  
  	mutex_lock(&genpd->lock);
  	/*
  	 * Wait for the domain to transition into either the active,
  	 * or the power off state.
  	 */
  	for (;;) {
  		prepare_to_wait(&genpd->status_wait_queue, &wait,
  				TASK_UNINTERRUPTIBLE);

  		if (genpd->status == GPD_STATE_ACTIVE
  		    || genpd->status == GPD_STATE_POWER_OFF)

  			break;
  		mutex_unlock(&genpd->lock);
  
  		schedule();
  
  		mutex_lock(&genpd->lock);
  	}
  	finish_wait(&genpd->status_wait_queue, &wait);
  }
  
  static void genpd_release_lock(struct generic_pm_domain *genpd)
  {
  	mutex_unlock(&genpd->lock);
  }

  static void genpd_set_active(struct generic_pm_domain *genpd)
  {
  	if (genpd->resume_count == 0)
  		genpd->status = GPD_STATE_ACTIVE;
  }

  /**

   * __pm_genpd_poweron - Restore power to a given PM domain and its masters.

   * @genpd: PM domain to power up.
   *

   * Restore power to @genpd and all of its masters so that it is possible to

   * resume a device belonging to it.
   */

  int __pm_genpd_poweron(struct generic_pm_domain *genpd)
  	__releases(&genpd->lock) __acquires(&genpd->lock)

  {

  	struct gpd_link *link;

  	DEFINE_WAIT(wait);

  	int ret = 0;

  	/* If the domain's master is being waited for, we have to wait too. */

  	for (;;) {
  		prepare_to_wait(&genpd->status_wait_queue, &wait,
  				TASK_UNINTERRUPTIBLE);

  		if (genpd->status != GPD_STATE_WAIT_MASTER)

  			break;
  		mutex_unlock(&genpd->lock);

  		schedule();
  
  		mutex_lock(&genpd->lock);
  	}
  	finish_wait(&genpd->status_wait_queue, &wait);

  	if (genpd->status == GPD_STATE_ACTIVE

  	    || (genpd->prepared_count > 0 && genpd->suspend_power_off))

  		return 0;

  	if (genpd->status != GPD_STATE_POWER_OFF) {
  		genpd_set_active(genpd);

  		return 0;

  	}

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

  		genpd->status = GPD_STATE_WAIT_MASTER;

  		mutex_unlock(&genpd->lock);

  		ret = pm_genpd_poweron(link->master);

  
  		mutex_lock(&genpd->lock);

  		/*
  		 * The "wait for parent" status is guaranteed not to change

  		 * while the master is powering on.

  		 */
  		genpd->status = GPD_STATE_POWER_OFF;
  		wake_up_all(&genpd->status_wait_queue);

  		if (ret) {
  			genpd_sd_counter_dec(link->master);

  			goto err;

  		}

  	}

  	if (genpd->power_on) {

  		ktime_t time_start = ktime_get();
  		s64 elapsed_ns;

  		ret = genpd->power_on(genpd);

  		if (ret)
  			goto err;

  
  		elapsed_ns = ktime_to_ns(ktime_sub(ktime_get(), time_start));

  		if (elapsed_ns > genpd->power_on_latency_ns) {

  			genpd->power_on_latency_ns = elapsed_ns;

  			if (genpd->name)
  				pr_warning("%s: Power-on latency exceeded, "
  					"new value %lld ns
  ", genpd->name,
  					elapsed_ns);
  		}

  	}

  	genpd_set_active(genpd);

  	return 0;

  
   err:

  	list_for_each_entry_continue_reverse(link, &genpd->slave_links, slave_node)
  		genpd_sd_counter_dec(link->master);

  	return ret;
  }
  
  /**

   * pm_genpd_poweron - Restore power to a given PM domain and its masters.

   * @genpd: PM domain to power up.
   */
  int pm_genpd_poweron(struct generic_pm_domain *genpd)
  {
  	int ret;
  
  	mutex_lock(&genpd->lock);
  	ret = __pm_genpd_poweron(genpd);
  	mutex_unlock(&genpd->lock);
  	return ret;

  }
  
  #endif /* CONFIG_PM */
  
  #ifdef CONFIG_PM_RUNTIME
  
  /**

   * __pm_genpd_save_device - Save the pre-suspend state of a device.

   * @pdd: Domain data of the device to save the state of.

   * @genpd: PM domain the device belongs to.
   */

  static int __pm_genpd_save_device(struct pm_domain_data *pdd,

  				  struct generic_pm_domain *genpd)

  	__releases(&genpd->lock) __acquires(&genpd->lock)

  {

  	struct generic_pm_domain_data *gpd_data = to_gpd_data(pdd);

  	struct device *dev = pdd->dev;

  	int ret = 0;

  	if (gpd_data->need_restore)

  		return 0;

  	mutex_unlock(&genpd->lock);

  	genpd_start_dev(genpd, dev);
  	ret = genpd_save_dev(genpd, dev);
  	genpd_stop_dev(genpd, dev);

  	mutex_lock(&genpd->lock);

  	if (!ret)

  		gpd_data->need_restore = true;

  
  	return ret;
  }
  
  /**
   * __pm_genpd_restore_device - Restore the pre-suspend state of a device.

   * @pdd: Domain data of the device to restore the state of.

   * @genpd: PM domain the device belongs to.
   */

  static void __pm_genpd_restore_device(struct pm_domain_data *pdd,

  				      struct generic_pm_domain *genpd)

  	__releases(&genpd->lock) __acquires(&genpd->lock)

  {

  	struct generic_pm_domain_data *gpd_data = to_gpd_data(pdd);

  	struct device *dev = pdd->dev;

  	if (!gpd_data->need_restore)

  		return;

  	mutex_unlock(&genpd->lock);

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

  	mutex_lock(&genpd->lock);

  	gpd_data->need_restore = false;

  }
  
  /**

   * genpd_abort_poweroff - Check if a PM domain power off should be aborted.
   * @genpd: PM domain to check.
   *
   * Return true if a PM domain's status changed to GPD_STATE_ACTIVE during
   * a "power off" operation, which means that a "power on" has occured in the
   * meantime, or if its resume_count field is different from zero, which means
   * that one of its devices has been resumed in the meantime.
   */
  static bool genpd_abort_poweroff(struct generic_pm_domain *genpd)
  {

  	return genpd->status == GPD_STATE_WAIT_MASTER

  		|| genpd->status == GPD_STATE_ACTIVE || genpd->resume_count > 0;

  }
  
  /**

   * genpd_queue_power_off_work - Queue up the execution of pm_genpd_poweroff().
   * @genpd: PM domait to power off.
   *
   * Queue up the execution of pm_genpd_poweroff() unless it's already been done
   * before.
   */

  void genpd_queue_power_off_work(struct generic_pm_domain *genpd)

  {
  	if (!work_pending(&genpd->power_off_work))
  		queue_work(pm_wq, &genpd->power_off_work);
  }
  
  /**

   * pm_genpd_poweroff - Remove power from a given PM domain.
   * @genpd: PM domain to power down.
   *
   * If all of the @genpd's devices have been suspended and all of its subdomains
   * have been powered down, run the runtime suspend callbacks provided by all of
   * the @genpd's devices' drivers and remove power from @genpd.
   */
  static int pm_genpd_poweroff(struct generic_pm_domain *genpd)

  	__releases(&genpd->lock) __acquires(&genpd->lock)

  {

  	struct pm_domain_data *pdd;

  	struct gpd_link *link;

  	unsigned int not_suspended;

  	int ret = 0;

   start:
  	/*
  	 * Do not try to power off the domain in the following situations:
  	 * (1) The domain is already in the "power off" state.

  	 * (2) The domain is waiting for its master to power up.

  	 * (3) One of the domain's devices is being resumed right now.

  	 * (4) System suspend is in progress.

  	 */

  	if (genpd->status == GPD_STATE_POWER_OFF

  	    || genpd->status == GPD_STATE_WAIT_MASTER

  	    || genpd->resume_count > 0 || genpd->prepared_count > 0)

  		return 0;

  	if (atomic_read(&genpd->sd_count) > 0)

  		return -EBUSY;
  
  	not_suspended = 0;

  	list_for_each_entry(pdd, &genpd->dev_list, list_node)

  		if (pdd->dev->driver && (!pm_runtime_suspended(pdd->dev)
  		    || pdd->dev->power.irq_safe))

  			not_suspended++;
  
  	if (not_suspended > genpd->in_progress)
  		return -EBUSY;

  	if (genpd->poweroff_task) {
  		/*
  		 * Another instance of pm_genpd_poweroff() is executing
  		 * callbacks, so tell it to start over and return.
  		 */
  		genpd->status = GPD_STATE_REPEAT;
  		return 0;
  	}

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

  	genpd->status = GPD_STATE_BUSY;

  	genpd->poweroff_task = current;

  	list_for_each_entry_reverse(pdd, &genpd->dev_list, list_node) {

  		ret = atomic_read(&genpd->sd_count) == 0 ?

  			__pm_genpd_save_device(pdd, genpd) : -EBUSY;

  
  		if (genpd_abort_poweroff(genpd))
  			goto out;

  		if (ret) {
  			genpd_set_active(genpd);
  			goto out;
  		}

  		if (genpd->status == GPD_STATE_REPEAT) {
  			genpd->poweroff_task = NULL;
  			goto start;
  		}
  	}

  	if (genpd->power_off) {

  		ktime_t time_start;
  		s64 elapsed_ns;

  		if (atomic_read(&genpd->sd_count) > 0) {
  			ret = -EBUSY;

  			goto out;
  		}

  		time_start = ktime_get();

  		/*

  		 * If sd_count > 0 at this point, one of the subdomains hasn't
  		 * managed to call pm_genpd_poweron() for the master yet after

  		 * incrementing it.  In that case pm_genpd_poweron() will wait
  		 * for us to drop the lock, so we can call .power_off() and let
  		 * the pm_genpd_poweron() restore power for us (this shouldn't
  		 * happen very often).
  		 */

  		ret = genpd->power_off(genpd);
  		if (ret == -EBUSY) {
  			genpd_set_active(genpd);

  			goto out;
  		}

  
  		elapsed_ns = ktime_to_ns(ktime_sub(ktime_get(), time_start));

  		if (elapsed_ns > genpd->power_off_latency_ns) {

  			genpd->power_off_latency_ns = elapsed_ns;

  			if (genpd->name)
  				pr_warning("%s: Power-off latency exceeded, "
  					"new value %lld ns
  ", genpd->name,
  					elapsed_ns);
  		}

  	}

  	genpd->status = GPD_STATE_POWER_OFF;

  	genpd->power_off_time = ktime_get();
  
  	/* Update PM QoS information for devices in the domain. */
  	list_for_each_entry_reverse(pdd, &genpd->dev_list, list_node) {
  		struct gpd_timing_data *td = &to_gpd_data(pdd)->td;
  
  		pm_runtime_update_max_time_suspended(pdd->dev,
  					td->start_latency_ns +
  					td->restore_state_latency_ns +
  					genpd->power_on_latency_ns);
  	}

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

   out:
  	genpd->poweroff_task = NULL;
  	wake_up_all(&genpd->status_wait_queue);
  	return ret;

  }
  
  /**
   * 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_acquire_lock(genpd);

  	pm_genpd_poweroff(genpd);

  	genpd_release_lock(genpd);

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

  	bool (*stop_ok)(struct device *__dev);

  	int ret;

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

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

  		return -EINVAL;

  	might_sleep_if(!genpd->dev_irq_safe);

  	stop_ok = genpd->gov ? genpd->gov->stop_ok : NULL;
  	if (stop_ok && !stop_ok(dev))
  		return -EBUSY;

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

  	pm_runtime_update_max_time_suspended(dev,
  				dev_gpd_data(dev)->td.start_latency_ns);

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

  	mutex_lock(&genpd->lock);

  	genpd->in_progress++;
  	pm_genpd_poweroff(genpd);
  	genpd->in_progress--;

  	mutex_unlock(&genpd->lock);

  
  	return 0;
  }
  
  /**

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

  	DEFINE_WAIT(wait);

  	int ret;
  
  	dev_dbg(dev, "%s()
  ", __func__);

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

  		return -EINVAL;

  	might_sleep_if(!genpd->dev_irq_safe);
  
  	/* If power.irq_safe, the PM domain is never powered off. */
  	if (dev->power.irq_safe)
  		goto out;

  	mutex_lock(&genpd->lock);

  	ret = __pm_genpd_poweron(genpd);
  	if (ret) {
  		mutex_unlock(&genpd->lock);
  		return ret;
  	}

  	genpd->status = GPD_STATE_BUSY;

  	genpd->resume_count++;
  	for (;;) {
  		prepare_to_wait(&genpd->status_wait_queue, &wait,
  				TASK_UNINTERRUPTIBLE);
  		/*
  		 * If current is the powering off task, we have been called
  		 * reentrantly from one of the device callbacks, so we should
  		 * not wait.
  		 */
  		if (!genpd->poweroff_task || genpd->poweroff_task == current)
  			break;
  		mutex_unlock(&genpd->lock);
  
  		schedule();
  
  		mutex_lock(&genpd->lock);
  	}
  	finish_wait(&genpd->status_wait_queue, &wait);

  	__pm_genpd_restore_device(dev->power.subsys_data->domain_data, genpd);

  	genpd->resume_count--;
  	genpd_set_active(genpd);

  	wake_up_all(&genpd->status_wait_queue);

  	mutex_unlock(&genpd->lock);

   out:

  	genpd_start_dev(genpd, dev);

  
  	return 0;
  }

  /**
   * pm_genpd_poweroff_unused - Power off all PM domains with no devices in use.
   */
  void pm_genpd_poweroff_unused(void)
  {
  	struct generic_pm_domain *genpd;
  
  	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);
  }

  #else
  
  static inline void genpd_power_off_work_fn(struct work_struct *work) {}
  
  #define pm_genpd_runtime_suspend	NULL
  #define pm_genpd_runtime_resume		NULL
  
  #endif /* CONFIG_PM_RUNTIME */

  #ifdef CONFIG_PM_SLEEP

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

  static int genpd_suspend_dev(struct generic_pm_domain *genpd, struct device *dev)
  {
  	return GENPD_DEV_CALLBACK(genpd, int, suspend, dev);
  }
  
  static int genpd_suspend_late(struct generic_pm_domain *genpd, struct device *dev)
  {
  	return GENPD_DEV_CALLBACK(genpd, int, suspend_late, dev);
  }
  
  static int genpd_resume_early(struct generic_pm_domain *genpd, struct device *dev)
  {
  	return GENPD_DEV_CALLBACK(genpd, int, resume_early, dev);
  }
  
  static int genpd_resume_dev(struct generic_pm_domain *genpd, struct device *dev)
  {
  	return GENPD_DEV_CALLBACK(genpd, int, resume, dev);
  }
  
  static int genpd_freeze_dev(struct generic_pm_domain *genpd, struct device *dev)
  {
  	return GENPD_DEV_CALLBACK(genpd, int, freeze, dev);
  }
  
  static int genpd_freeze_late(struct generic_pm_domain *genpd, struct device *dev)
  {
  	return GENPD_DEV_CALLBACK(genpd, int, freeze_late, dev);
  }
  
  static int genpd_thaw_early(struct generic_pm_domain *genpd, struct device *dev)
  {
  	return GENPD_DEV_CALLBACK(genpd, int, thaw_early, dev);
  }
  
  static int genpd_thaw_dev(struct generic_pm_domain *genpd, struct device *dev)
  {
  	return GENPD_DEV_CALLBACK(genpd, int, thaw, dev);
  }

  /**

   * pm_genpd_sync_poweroff - Synchronously power off a PM domain and its masters.

   * @genpd: PM domain to power off, if possible.
   *
   * Check if the given PM domain can be powered off (during system suspend or

   * hibernation) and do that if so.  Also, in that case propagate to its masters.

   *
   * This function is only called in "noirq" stages of system power transitions,
   * so it need not acquire locks (all of the "noirq" callbacks are executed
   * sequentially, so it is guaranteed that it will never run twice in parallel).
   */
  static void pm_genpd_sync_poweroff(struct generic_pm_domain *genpd)
  {

  	struct gpd_link *link;

  	if (genpd->status == GPD_STATE_POWER_OFF)

  		return;

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

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

  	genpd->status = GPD_STATE_POWER_OFF;

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

  	}
  }
  
  /**

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

  	active_wakeup = genpd_dev_active_wakeup(genpd, dev);

  	return device_may_wakeup(dev) ? active_wakeup : !active_wakeup;
  }
  
  /**

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

  	int ret;

  
  	dev_dbg(dev, "%s()
  ", __func__);
  
  	genpd = dev_to_genpd(dev);
  	if (IS_ERR(genpd))
  		return -EINVAL;

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

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

  	genpd_acquire_lock(genpd);

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

  		genpd->suspend_power_off = genpd->status == GPD_STATE_POWER_OFF;
  
  	genpd_release_lock(genpd);

  
  	if (genpd->suspend_power_off) {

  		pm_runtime_put_noidle(dev);

  		return 0;
  	}
  
  	/*

  	 * The PM domain must be in the GPD_STATE_ACTIVE state at this point,
  	 * so pm_genpd_poweron() will return immediately, but if the device

  	 * is suspended (e.g. it's been stopped by genpd_stop_dev()), we need

  	 * to make it operational.

  	 */

  	pm_runtime_resume(dev);

  	__pm_runtime_disable(dev, false);

  	ret = pm_generic_prepare(dev);
  	if (ret) {
  		mutex_lock(&genpd->lock);
  
  		if (--genpd->prepared_count == 0)
  			genpd->suspend_power_off = false;
  
  		mutex_unlock(&genpd->lock);

  		pm_runtime_enable(dev);

  	}

  
  	pm_runtime_put_sync(dev);

  	return ret;

  }
  
  /**
   * pm_genpd_suspend - Suspend a device belonging to an I/O PM domain.
   * @dev: Device to suspend.
   *
   * Suspend a device under the assumption that its pm_domain field points to the
   * domain member of an object of type struct generic_pm_domain representing
   * a PM domain consisting of I/O devices.
   */
  static int pm_genpd_suspend(struct device *dev)
  {
  	struct generic_pm_domain *genpd;
  
  	dev_dbg(dev, "%s()
  ", __func__);
  
  	genpd = dev_to_genpd(dev);
  	if (IS_ERR(genpd))
  		return -EINVAL;

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

  }
  
  /**
   * pm_genpd_suspend_noirq - Late suspend of a device from an I/O PM domain.
   * @dev: Device to suspend.
   *
   * Carry out a late suspend of a device under the assumption that its
   * pm_domain field points to the domain member of an object of type
   * struct generic_pm_domain representing a PM domain consisting of I/O devices.
   */
  static int pm_genpd_suspend_noirq(struct device *dev)
  {
  	struct generic_pm_domain *genpd;
  	int ret;
  
  	dev_dbg(dev, "%s()
  ", __func__);
  
  	genpd = dev_to_genpd(dev);
  	if (IS_ERR(genpd))
  		return -EINVAL;
  
  	if (genpd->suspend_power_off)
  		return 0;

  	ret = genpd_suspend_late(genpd, dev);

  	if (ret)
  		return ret;

  	if (dev->power.wakeup_path && genpd_dev_active_wakeup(genpd, dev))

  		return 0;

  	genpd_stop_dev(genpd, dev);

  
  	/*
  	 * Since all of the "noirq" callbacks are executed sequentially, it is
  	 * guaranteed that this function will never run twice in parallel for
  	 * the same PM domain, so it is not necessary to use locking here.
  	 */
  	genpd->suspended_count++;
  	pm_genpd_sync_poweroff(genpd);
  
  	return 0;
  }
  
  /**
   * pm_genpd_resume_noirq - Early resume of a device from an I/O power domain.
   * @dev: Device to resume.
   *
   * Carry out an early resume of a device under the assumption that its
   * pm_domain field points to the domain member of an object of type
   * struct generic_pm_domain representing a power domain consisting of I/O
   * devices.
   */
  static int pm_genpd_resume_noirq(struct device *dev)
  {
  	struct generic_pm_domain *genpd;
  
  	dev_dbg(dev, "%s()
  ", __func__);
  
  	genpd = dev_to_genpd(dev);
  	if (IS_ERR(genpd))
  		return -EINVAL;
  
  	if (genpd->suspend_power_off)
  		return 0;
  
  	/*
  	 * Since all of the "noirq" callbacks are executed sequentially, it is
  	 * guaranteed that this function will never run twice in parallel for
  	 * the same PM domain, so it is not necessary to use locking here.
  	 */
  	pm_genpd_poweron(genpd);
  	genpd->suspended_count--;

  	genpd_start_dev(genpd, dev);

  	return genpd_resume_early(genpd, dev);

  }
  
  /**
   * pm_genpd_resume - Resume a device belonging to an I/O power domain.
   * @dev: Device to resume.
   *
   * Resume a device under the assumption that its pm_domain field points to the
   * domain member of an object of type struct generic_pm_domain representing
   * a power domain consisting of I/O devices.
   */
  static int pm_genpd_resume(struct device *dev)
  {
  	struct generic_pm_domain *genpd;
  
  	dev_dbg(dev, "%s()
  ", __func__);
  
  	genpd = dev_to_genpd(dev);
  	if (IS_ERR(genpd))
  		return -EINVAL;

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

  }
  
  /**
   * pm_genpd_freeze - Freeze a device belonging to an I/O power domain.
   * @dev: Device to freeze.
   *
   * Freeze a device under the assumption that its pm_domain field points to the
   * domain member of an object of type struct generic_pm_domain representing
   * a power domain consisting of I/O devices.
   */
  static int pm_genpd_freeze(struct device *dev)
  {
  	struct generic_pm_domain *genpd;
  
  	dev_dbg(dev, "%s()
  ", __func__);
  
  	genpd = dev_to_genpd(dev);
  	if (IS_ERR(genpd))
  		return -EINVAL;

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

  }
  
  /**
   * pm_genpd_freeze_noirq - Late freeze of a device from an I/O power domain.
   * @dev: Device to freeze.
   *
   * Carry out a late freeze of a device under the assumption that its
   * pm_domain field points to the domain member of an object of type
   * struct generic_pm_domain representing a power domain consisting of I/O
   * devices.
   */
  static int pm_genpd_freeze_noirq(struct device *dev)
  {
  	struct generic_pm_domain *genpd;
  	int ret;
  
  	dev_dbg(dev, "%s()
  ", __func__);
  
  	genpd = dev_to_genpd(dev);
  	if (IS_ERR(genpd))
  		return -EINVAL;
  
  	if (genpd->suspend_power_off)
  		return 0;

  	ret = genpd_freeze_late(genpd, dev);

  	if (ret)
  		return ret;

  	genpd_stop_dev(genpd, dev);

  
  	return 0;
  }
  
  /**
   * pm_genpd_thaw_noirq - Early thaw of a device from an I/O power domain.
   * @dev: Device to thaw.
   *
   * Carry out an early thaw of a device under the assumption that its
   * pm_domain field points to the domain member of an object of type
   * struct generic_pm_domain representing a power domain consisting of I/O
   * devices.
   */
  static int pm_genpd_thaw_noirq(struct device *dev)
  {
  	struct generic_pm_domain *genpd;
  
  	dev_dbg(dev, "%s()
  ", __func__);
  
  	genpd = dev_to_genpd(dev);
  	if (IS_ERR(genpd))
  		return -EINVAL;
  
  	if (genpd->suspend_power_off)
  		return 0;

  	genpd_start_dev(genpd, dev);

  	return genpd_thaw_early(genpd, dev);

  }
  
  /**
   * pm_genpd_thaw - Thaw a device belonging to an I/O power domain.
   * @dev: Device to thaw.
   *
   * Thaw a device under the assumption that its pm_domain field points to the
   * domain member of an object of type struct generic_pm_domain representing
   * a power domain consisting of I/O devices.
   */
  static int pm_genpd_thaw(struct device *dev)
  {
  	struct generic_pm_domain *genpd;
  
  	dev_dbg(dev, "%s()
  ", __func__);
  
  	genpd = dev_to_genpd(dev);
  	if (IS_ERR(genpd))
  		return -EINVAL;

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

  }
  
  /**
   * pm_genpd_restore_noirq - Early restore of a device from an I/O power domain.
   * @dev: Device to resume.
   *
   * Carry out an early restore of a device under the assumption that its
   * pm_domain field points to the domain member of an object of type
   * struct generic_pm_domain representing a power domain consisting of I/O
   * devices.
   */
  static int pm_genpd_restore_noirq(struct device *dev)
  {
  	struct generic_pm_domain *genpd;
  
  	dev_dbg(dev, "%s()
  ", __func__);
  
  	genpd = dev_to_genpd(dev);
  	if (IS_ERR(genpd))
  		return -EINVAL;
  
  	/*
  	 * Since all of the "noirq" callbacks are executed sequentially, it is
  	 * guaranteed that this function will never run twice in parallel for
  	 * the same PM domain, so it is not necessary to use locking here.
  	 */

  	genpd->status = GPD_STATE_POWER_OFF;

  	if (genpd->suspend_power_off) {
  		/*
  		 * The boot kernel might put the domain into the power on state,
  		 * so make sure it really is powered off.
  		 */
  		if (genpd->power_off)
  			genpd->power_off(genpd);
  		return 0;
  	}
  
  	pm_genpd_poweron(genpd);
  	genpd->suspended_count--;

  	genpd_start_dev(genpd, dev);

  	return genpd_resume_early(genpd, dev);

  }
  
  /**
   * pm_genpd_complete - Complete power transition of a device in a power domain.
   * @dev: Device to complete the transition of.
   *
   * Complete a power transition of a device (during a system-wide power
   * transition) under the assumption that its pm_domain field points to the
   * domain member of an object of type struct generic_pm_domain representing
   * a power domain consisting of I/O devices.
   */
  static void pm_genpd_complete(struct device *dev)
  {
  	struct generic_pm_domain *genpd;
  	bool run_complete;
  
  	dev_dbg(dev, "%s()
  ", __func__);
  
  	genpd = dev_to_genpd(dev);
  	if (IS_ERR(genpd))
  		return;
  
  	mutex_lock(&genpd->lock);
  
  	run_complete = !genpd->suspend_power_off;
  	if (--genpd->prepared_count == 0)
  		genpd->suspend_power_off = false;
  
  	mutex_unlock(&genpd->lock);
  
  	if (run_complete) {
  		pm_generic_complete(dev);

  		pm_runtime_set_active(dev);

  		pm_runtime_enable(dev);

  		pm_runtime_idle(dev);

  	}
  }
  
  #else
  
  #define pm_genpd_prepare		NULL
  #define pm_genpd_suspend		NULL
  #define pm_genpd_suspend_noirq		NULL
  #define pm_genpd_resume_noirq		NULL
  #define pm_genpd_resume			NULL
  #define pm_genpd_freeze			NULL
  #define pm_genpd_freeze_noirq		NULL
  #define pm_genpd_thaw_noirq		NULL
  #define pm_genpd_thaw			NULL

  #define pm_genpd_restore_noirq		NULL

  #define pm_genpd_complete		NULL
  
  #endif /* CONFIG_PM_SLEEP */

  /**

   * __pm_genpd_add_device - Add a device to an I/O PM domain.

   * @genpd: PM domain to add the device to.
   * @dev: Device to be added.

   * @td: Set of PM QoS timing parameters to attach to the device.

   */

  int __pm_genpd_add_device(struct generic_pm_domain *genpd, struct device *dev,
  			  struct gpd_timing_data *td)

  {

  	struct generic_pm_domain_data *gpd_data;

  	struct pm_domain_data *pdd;

  	int ret = 0;
  
  	dev_dbg(dev, "%s()
  ", __func__);
  
  	if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(dev))
  		return -EINVAL;

  	genpd_acquire_lock(genpd);

  	if (genpd->status == GPD_STATE_POWER_OFF) {

  		ret = -EINVAL;
  		goto out;
  	}

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

  	list_for_each_entry(pdd, &genpd->dev_list, list_node)
  		if (pdd->dev == dev) {

  			ret = -EINVAL;
  			goto out;
  		}

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

  	genpd->device_count++;

  	dev->pm_domain = &genpd->domain;

  	dev_pm_get_subsys_data(dev);

  	dev->power.subsys_data->domain_data = &gpd_data->base;
  	gpd_data->base.dev = dev;
  	gpd_data->need_restore = false;
  	list_add_tail(&gpd_data->base.list_node, &genpd->dev_list);

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

  
   out:

  	genpd_release_lock(genpd);

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

  	struct pm_domain_data *pdd;

  	int ret = -EINVAL;
  
  	dev_dbg(dev, "%s()
  ", __func__);
  
  	if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(dev))
  		return -EINVAL;

  	genpd_acquire_lock(genpd);

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

  	list_for_each_entry(pdd, &genpd->dev_list, list_node) {
  		if (pdd->dev != dev)

  			continue;

  		list_del_init(&pdd->list_node);
  		pdd->dev = NULL;
  		dev_pm_put_subsys_data(dev);

  		dev->pm_domain = NULL;

  		kfree(to_gpd_data(pdd));

  		genpd->device_count--;

  
  		ret = 0;
  		break;
  	}

   out:

  	genpd_release_lock(genpd);

  
  	return ret;
  }
  
  /**
   * pm_genpd_add_subdomain - Add a subdomain to an I/O PM domain.
   * @genpd: Master PM domain to add the subdomain to.

   * @subdomain: Subdomain to be added.

   */
  int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,

  			   struct generic_pm_domain *subdomain)

  {

  	struct gpd_link *link;

  	int ret = 0;

  	if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(subdomain))

  		return -EINVAL;

   start:
  	genpd_acquire_lock(genpd);

  	mutex_lock_nested(&subdomain->lock, SINGLE_DEPTH_NESTING);

  	if (subdomain->status != GPD_STATE_POWER_OFF
  	    && subdomain->status != GPD_STATE_ACTIVE) {
  		mutex_unlock(&subdomain->lock);

  		genpd_release_lock(genpd);
  		goto start;
  	}
  
  	if (genpd->status == GPD_STATE_POWER_OFF

  	    &&  subdomain->status != GPD_STATE_POWER_OFF) {

  		ret = -EINVAL;
  		goto out;
  	}

  	list_for_each_entry(link, &genpd->slave_links, slave_node) {

  		if (link->slave == subdomain && link->master == genpd) {

  			ret = -EINVAL;
  			goto out;
  		}
  	}

  	link = kzalloc(sizeof(*link), GFP_KERNEL);
  	if (!link) {
  		ret = -ENOMEM;
  		goto out;
  	}
  	link->master = genpd;
  	list_add_tail(&link->master_node, &genpd->master_links);

  	link->slave = subdomain;
  	list_add_tail(&link->slave_node, &subdomain->slave_links);
  	if (subdomain->status != GPD_STATE_POWER_OFF)

  		genpd_sd_counter_inc(genpd);

   out:

  	mutex_unlock(&subdomain->lock);

  	genpd_release_lock(genpd);

  
  	return ret;
  }
  
  /**
   * pm_genpd_remove_subdomain - Remove a subdomain from an I/O PM domain.
   * @genpd: Master PM domain to remove the subdomain from.

   * @subdomain: Subdomain to be removed.

   */
  int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,

  			      struct generic_pm_domain *subdomain)

  {

  	struct gpd_link *link;

  	int ret = -EINVAL;

  	if (IS_ERR_OR_NULL(genpd) || IS_ERR_OR_NULL(subdomain))

  		return -EINVAL;

   start:
  	genpd_acquire_lock(genpd);

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

  			continue;
  
  		mutex_lock_nested(&subdomain->lock, SINGLE_DEPTH_NESTING);

  		if (subdomain->status != GPD_STATE_POWER_OFF
  		    && subdomain->status != GPD_STATE_ACTIVE) {
  			mutex_unlock(&subdomain->lock);
  			genpd_release_lock(genpd);
  			goto start;
  		}

  		list_del(&link->master_node);
  		list_del(&link->slave_node);
  		kfree(link);

  		if (subdomain->status != GPD_STATE_POWER_OFF)

  			genpd_sd_counter_dec(genpd);
  
  		mutex_unlock(&subdomain->lock);
  
  		ret = 0;
  		break;
  	}

  	genpd_release_lock(genpd);

  
  	return ret;
  }
  
  /**

   * pm_genpd_add_callbacks - Add PM domain callbacks to a given device.
   * @dev: Device to add the callbacks to.
   * @ops: Set of callbacks to add.

   * @td: Timing data to add to the device along with the callbacks (optional).

   */

  int pm_genpd_add_callbacks(struct device *dev, struct gpd_dev_ops *ops,
  			   struct gpd_timing_data *td)

  {
  	struct pm_domain_data *pdd;
  	int ret = 0;
  
  	if (!(dev && dev->power.subsys_data && ops))
  		return -EINVAL;
  
  	pm_runtime_disable(dev);
  	device_pm_lock();
  
  	pdd = dev->power.subsys_data->domain_data;
  	if (pdd) {
  		struct generic_pm_domain_data *gpd_data = to_gpd_data(pdd);
  
  		gpd_data->ops = *ops;

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

  	} else {
  		ret = -EINVAL;
  	}
  
  	device_pm_unlock();
  	pm_runtime_enable(dev);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(pm_genpd_add_callbacks);
  
  /**

   * __pm_genpd_remove_callbacks - Remove PM domain callbacks from a given device.

   * @dev: Device to remove the callbacks from.

   * @clear_td: If set, clear the device's timing data too.

   */

  int __pm_genpd_remove_callbacks(struct device *dev, bool clear_td)

  {
  	struct pm_domain_data *pdd;
  	int ret = 0;
  
  	if (!(dev && dev->power.subsys_data))
  		return -EINVAL;
  
  	pm_runtime_disable(dev);
  	device_pm_lock();
  
  	pdd = dev->power.subsys_data->domain_data;
  	if (pdd) {
  		struct generic_pm_domain_data *gpd_data = to_gpd_data(pdd);
  
  		gpd_data->ops = (struct gpd_dev_ops){ 0 };

  		if (clear_td)
  			gpd_data->td = (struct gpd_timing_data){ 0 };

  	} else {
  		ret = -EINVAL;
  	}
  
  	device_pm_unlock();
  	pm_runtime_enable(dev);
  
  	return ret;
  }

  EXPORT_SYMBOL_GPL(__pm_genpd_remove_callbacks);

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

  /**

   * pm_genpd_default_save_state - Default "save device state" for PM domians.
   * @dev: Device to handle.
   */
  static int pm_genpd_default_save_state(struct device *dev)
  {
  	int (*cb)(struct device *__dev);
  	struct device_driver *drv = dev->driver;
  
  	cb = dev_gpd_data(dev)->ops.save_state;
  	if (cb)
  		return cb(dev);
  
  	if (drv && drv->pm && drv->pm->runtime_suspend)
  		return drv->pm->runtime_suspend(dev);
  
  	return 0;
  }
  
  /**
   * pm_genpd_default_restore_state - Default PM domians "restore device state".
   * @dev: Device to handle.
   */
  static int pm_genpd_default_restore_state(struct device *dev)
  {
  	int (*cb)(struct device *__dev);
  	struct device_driver *drv = dev->driver;
  
  	cb = dev_gpd_data(dev)->ops.restore_state;
  	if (cb)
  		return cb(dev);
  
  	if (drv && drv->pm && drv->pm->runtime_resume)
  		return drv->pm->runtime_resume(dev);
  
  	return 0;
  }

  #ifdef CONFIG_PM_SLEEP

  /**

   * pm_genpd_default_suspend - Default "device suspend" for PM domians.
   * @dev: Device to handle.
   */
  static int pm_genpd_default_suspend(struct device *dev)
  {

  	int (*cb)(struct device *__dev) = dev_gpd_data(dev)->ops.suspend;

  
  	return cb ? cb(dev) : pm_generic_suspend(dev);
  }
  
  /**
   * pm_genpd_default_suspend_late - Default "late device suspend" for PM domians.
   * @dev: Device to handle.
   */
  static int pm_genpd_default_suspend_late(struct device *dev)
  {

  	int (*cb)(struct device *__dev) = dev_gpd_data(dev)->ops.suspend_late;

  
  	return cb ? cb(dev) : pm_generic_suspend_noirq(dev);
  }
  
  /**
   * pm_genpd_default_resume_early - Default "early device resume" for PM domians.
   * @dev: Device to handle.
   */
  static int pm_genpd_default_resume_early(struct device *dev)
  {

  	int (*cb)(struct device *__dev) = dev_gpd_data(dev)->ops.resume_early;

  
  	return cb ? cb(dev) : pm_generic_resume_noirq(dev);
  }
  
  /**
   * pm_genpd_default_resume - Default "device resume" for PM domians.
   * @dev: Device to handle.
   */
  static int pm_genpd_default_resume(struct device *dev)
  {

  	int (*cb)(struct device *__dev) = dev_gpd_data(dev)->ops.resume;

  
  	return cb ? cb(dev) : pm_generic_resume(dev);
  }
  
  /**
   * pm_genpd_default_freeze - Default "device freeze" for PM domians.
   * @dev: Device to handle.
   */
  static int pm_genpd_default_freeze(struct device *dev)
  {
  	int (*cb)(struct device *__dev) = dev_gpd_data(dev)->ops.freeze;
  
  	return cb ? cb(dev) : pm_generic_freeze(dev);
  }
  
  /**
   * pm_genpd_default_freeze_late - Default "late device freeze" for PM domians.
   * @dev: Device to handle.
   */
  static int pm_genpd_default_freeze_late(struct device *dev)
  {
  	int (*cb)(struct device *__dev) = dev_gpd_data(dev)->ops.freeze_late;
  
  	return cb ? cb(dev) : pm_generic_freeze_noirq(dev);
  }
  
  /**
   * pm_genpd_default_thaw_early - Default "early device thaw" for PM domians.
   * @dev: Device to handle.
   */
  static int pm_genpd_default_thaw_early(struct device *dev)
  {
  	int (*cb)(struct device *__dev) = dev_gpd_data(dev)->ops.thaw_early;
  
  	return cb ? cb(dev) : pm_generic_thaw_noirq(dev);
  }
  
  /**
   * pm_genpd_default_thaw - Default "device thaw" for PM domians.
   * @dev: Device to handle.
   */
  static int pm_genpd_default_thaw(struct device *dev)
  {
  	int (*cb)(struct device *__dev) = dev_gpd_data(dev)->ops.thaw;
  
  	return cb ? cb(dev) : pm_generic_thaw(dev);
  }

  #else /* !CONFIG_PM_SLEEP */
  
  #define pm_genpd_default_suspend	NULL
  #define pm_genpd_default_suspend_late	NULL
  #define pm_genpd_default_resume_early	NULL
  #define pm_genpd_default_resume		NULL
  #define pm_genpd_default_freeze		NULL
  #define pm_genpd_default_freeze_late	NULL
  #define pm_genpd_default_thaw_early	NULL
  #define pm_genpd_default_thaw		NULL
  
  #endif /* !CONFIG_PM_SLEEP */

  /**

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

  	INIT_LIST_HEAD(&genpd->master_links);
  	INIT_LIST_HEAD(&genpd->slave_links);

  	INIT_LIST_HEAD(&genpd->dev_list);

  	mutex_init(&genpd->lock);
  	genpd->gov = gov;
  	INIT_WORK(&genpd->power_off_work, genpd_power_off_work_fn);
  	genpd->in_progress = 0;

  	atomic_set(&genpd->sd_count, 0);

  	genpd->status = is_off ? GPD_STATE_POWER_OFF : GPD_STATE_ACTIVE;
  	init_waitqueue_head(&genpd->status_wait_queue);

  	genpd->poweroff_task = NULL;
  	genpd->resume_count = 0;

  	genpd->device_count = 0;
  	genpd->suspended_count = 0;

  	genpd->max_off_time_ns = -1;

  	genpd->domain.ops.runtime_suspend = pm_genpd_runtime_suspend;
  	genpd->domain.ops.runtime_resume = pm_genpd_runtime_resume;
  	genpd->domain.ops.runtime_idle = pm_generic_runtime_idle;

  	genpd->domain.ops.prepare = pm_genpd_prepare;
  	genpd->domain.ops.suspend = pm_genpd_suspend;
  	genpd->domain.ops.suspend_noirq = pm_genpd_suspend_noirq;
  	genpd->domain.ops.resume_noirq = pm_genpd_resume_noirq;
  	genpd->domain.ops.resume = pm_genpd_resume;
  	genpd->domain.ops.freeze = pm_genpd_freeze;
  	genpd->domain.ops.freeze_noirq = pm_genpd_freeze_noirq;
  	genpd->domain.ops.thaw_noirq = pm_genpd_thaw_noirq;
  	genpd->domain.ops.thaw = pm_genpd_thaw;

  	genpd->domain.ops.poweroff = pm_genpd_suspend;
  	genpd->domain.ops.poweroff_noirq = pm_genpd_suspend_noirq;

  	genpd->domain.ops.restore_noirq = pm_genpd_restore_noirq;

  	genpd->domain.ops.restore = pm_genpd_resume;

  	genpd->domain.ops.complete = pm_genpd_complete;

  	genpd->dev_ops.save_state = pm_genpd_default_save_state;
  	genpd->dev_ops.restore_state = pm_genpd_default_restore_state;

  	genpd->dev_ops.suspend = pm_genpd_default_suspend;
  	genpd->dev_ops.suspend_late = pm_genpd_default_suspend_late;
  	genpd->dev_ops.resume_early = pm_genpd_default_resume_early;
  	genpd->dev_ops.resume = pm_genpd_default_resume;

  	genpd->dev_ops.freeze = pm_genpd_default_freeze;
  	genpd->dev_ops.freeze_late = pm_genpd_default_freeze_late;
  	genpd->dev_ops.thaw_early = pm_genpd_default_thaw_early;
  	genpd->dev_ops.thaw = pm_genpd_default_thaw;

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