drivers/base/power/domain_governor.c - maze/linux - Git at Google

 /*
  * drivers/base/power/domain_governor.c - Governors for device PM domains.
  *
  * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
  *
  * This file is released under the GPLv2.
  */

 #include <linux/kernel.h>
 #include <linux/pm_domain.h>
 #include <linux/pm_qos.h>
 #include <linux/hrtimer.h>

 #ifdef CONFIG_PM_RUNTIME

 static int dev_update_qos_constraint(struct device *dev, void *data)
 {
 	s64 *constraint_ns_p = data;
 	s32 constraint_ns = -1;

 	if (dev->power.subsys_data && dev->power.subsys_data->domain_data)
 		constraint_ns = dev_gpd_data(dev)->td.effective_constraint_ns;

 	if (constraint_ns < 0) {
 		constraint_ns = dev_pm_qos_read_value(dev);
 		constraint_ns *= NSEC_PER_USEC;
 	}
 	if (constraint_ns == 0)
 		return 0;

 	/*
 	 * constraint_ns cannot be negative here, because the device has been
 	 * suspended.
 	 */
 	if (constraint_ns < *constraint_ns_p || *constraint_ns_p == 0)
 		*constraint_ns_p = constraint_ns;

 	return 0;
 }

 /**
  * default_stop_ok - Default PM domain governor routine for stopping devices.
  * @dev: Device to check.
  */
 bool default_stop_ok(struct device *dev)
 {
 	struct gpd_timing_data *td = &dev_gpd_data(dev)->td;
 	unsigned long flags;
 	s64 constraint_ns;

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

 	spin_lock_irqsave(&dev->power.lock, flags);

 	if (!td->constraint_changed) {
 		bool ret = td->cached_stop_ok;

 		spin_unlock_irqrestore(&dev->power.lock, flags);
 		return ret;
 	}
 	td->constraint_changed = false;
 	td->cached_stop_ok = false;
 	td->effective_constraint_ns = -1;
 	constraint_ns = __dev_pm_qos_read_value(dev);

 	spin_unlock_irqrestore(&dev->power.lock, flags);

 	if (constraint_ns < 0)
 		return false;

 	constraint_ns *= NSEC_PER_USEC;
 	/*
 	 * We can walk the children without any additional locking, because
 	 * they all have been suspended at this point and their
 	 * effective_constraint_ns fields won't be modified in parallel with us.
 	 */
 	if (!dev->power.ignore_children)
 		device_for_each_child(dev, &constraint_ns,
 				      dev_update_qos_constraint);

 	if (constraint_ns > 0) {
 		constraint_ns -= td->start_latency_ns;
 		if (constraint_ns == 0)
 			return false;
 	}
 	td->effective_constraint_ns = constraint_ns;
 	td->cached_stop_ok = constraint_ns > td->stop_latency_ns ||
 				constraint_ns == 0;
 	/*
 	 * The children have been suspended already, so we don't need to take
 	 * their stop latencies into account here.
 	 */
 	return td->cached_stop_ok;
 }

 /**
  * default_power_down_ok - Default generic PM domain power off governor routine.
  * @pd: PM domain to check.
  *
  * This routine must be executed under the PM domain's lock.
  */
 static bool default_power_down_ok(struct dev_pm_domain *pd)
 {
 	struct generic_pm_domain *genpd = pd_to_genpd(pd);
 	struct gpd_link *link;
 	struct pm_domain_data *pdd;
 	s64 min_off_time_ns;
 	s64 off_on_time_ns;

 	if (genpd->max_off_time_changed) {
 		struct gpd_link *link;

 		/*
 		 * We have to invalidate the cached results for the masters, so
 		 * use the observation that default_power_down_ok() is not
 		 * going to be called for any master until this instance
 		 * returns.
 		 */
 		list_for_each_entry(link, &genpd->slave_links, slave_node)
 			link->master->max_off_time_changed = true;

 		genpd->max_off_time_changed = false;
 		genpd->cached_power_down_ok = false;
 		genpd->max_off_time_ns = -1;
 	} else {
 		return genpd->cached_power_down_ok;
 	}

 	off_on_time_ns = genpd->power_off_latency_ns +
 				genpd->power_on_latency_ns;
 	/*
 	 * It doesn't make sense to remove power from the domain if saving
 	 * the state of all devices in it and the power off/power on operations
 	 * take too much time.
 	 *
 	 * All devices in this domain have been stopped already at this point.
 	 */
 	list_for_each_entry(pdd, &genpd->dev_list, list_node) {
 		if (pdd->dev->driver)
 			off_on_time_ns +=
 				to_gpd_data(pdd)->td.save_state_latency_ns;
 	}

 	min_off_time_ns = -1;
 	/*
 	 * Check if subdomains can be off for enough time.
 	 *
 	 * All subdomains have been powered off already at this point.
 	 */
 	list_for_each_entry(link, &genpd->master_links, master_node) {
 		struct generic_pm_domain *sd = link->slave;
 		s64 sd_max_off_ns = sd->max_off_time_ns;

 		if (sd_max_off_ns < 0)
 			continue;

 		/*
 		 * Check if the subdomain is allowed to be off long enough for
 		 * the current domain to turn off and on (that's how much time
 		 * it will have to wait worst case).
 		 */
 		if (sd_max_off_ns <= off_on_time_ns)
 			return false;

 		if (min_off_time_ns > sd_max_off_ns || min_off_time_ns < 0)
 			min_off_time_ns = sd_max_off_ns;
 	}

 	/*
 	 * Check if the devices in the domain can be off enough time.
 	 */
 	list_for_each_entry(pdd, &genpd->dev_list, list_node) {
 		struct gpd_timing_data *td;
 		s64 constraint_ns;

 		if (!pdd->dev->driver)
 			continue;

 		/*
 		 * Check if the device is allowed to be off long enough for the
 		 * domain to turn off and on (that's how much time it will
 		 * have to wait worst case).
 		 */
 		td = &to_gpd_data(pdd)->td;
 		constraint_ns = td->effective_constraint_ns;
 		/* default_stop_ok() need not be called before us. */
 		if (constraint_ns < 0) {
 			constraint_ns = dev_pm_qos_read_value(pdd->dev);
 			constraint_ns *= NSEC_PER_USEC;
 		}
 		if (constraint_ns == 0)
 			continue;

 		/*
 		 * constraint_ns cannot be negative here, because the device has
 		 * been suspended.
 		 */
 		constraint_ns -= td->restore_state_latency_ns;
 		if (constraint_ns <= off_on_time_ns)
 			return false;

 		if (min_off_time_ns > constraint_ns || min_off_time_ns < 0)
 			min_off_time_ns = constraint_ns;
 	}

 	genpd->cached_power_down_ok = true;

 	/*
 	 * If the computed minimum device off time is negative, there are no
 	 * latency constraints, so the domain can spend arbitrary time in the
 	 * "off" state.
 	 */
 	if (min_off_time_ns < 0)
 		return true;

 	/*
 	 * The difference between the computed minimum subdomain or device off
 	 * time and the time needed to turn the domain on is the maximum
 	 * theoretical time this domain can spend in the "off" state.
 	 */
 	genpd->max_off_time_ns = min_off_time_ns - genpd->power_on_latency_ns;
 	return true;
 }

 static bool always_on_power_down_ok(struct dev_pm_domain *domain)
 {
 	return false;
 }

 #else /* !CONFIG_PM_RUNTIME */

 bool default_stop_ok(struct device *dev)
 {
 	return false;
 }

 #define default_power_down_ok	NULL
 #define always_on_power_down_ok	NULL

 #endif /* !CONFIG_PM_RUNTIME */

 struct dev_power_governor simple_qos_governor = {
 	.stop_ok = default_stop_ok,
 	.power_down_ok = default_power_down_ok,
 };

 /**
  * pm_genpd_gov_always_on - A governor implementing an always-on policy
  */
 struct dev_power_governor pm_domain_always_on_gov = {
 	.power_down_ok = always_on_power_down_ok,
 	.stop_ok = default_stop_ok,
 };
	/*
	* drivers/base/power/domain_governor.c - Governors for device PM domains.
	*
	* Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
	*
	* This file is released under the GPLv2.
	*/

	#include <linux/kernel.h>
	#include <linux/pm_domain.h>
	#include <linux/pm_qos.h>
	#include <linux/hrtimer.h>

	#ifdef CONFIG_PM_RUNTIME

	static int dev_update_qos_constraint(struct device dev, void data)
	{
	s64 *constraint_ns_p = data;
	s32 constraint_ns = -1;

	if (dev->power.subsys_data && dev->power.subsys_data->domain_data)
	constraint_ns = dev_gpd_data(dev)->td.effective_constraint_ns;

	if (constraint_ns < 0) {
	constraint_ns = dev_pm_qos_read_value(dev);
	constraint_ns *= NSEC_PER_USEC;
	}
	if (constraint_ns == 0)
	return 0;

	/*
	* constraint_ns cannot be negative here, because the device has been
	* suspended.
	*/
	if (constraint_ns < constraint_ns_p \|\| constraint_ns_p == 0)
	*constraint_ns_p = constraint_ns;

	return 0;
	}

	/**
	* default_stop_ok - Default PM domain governor routine for stopping devices.
	* @dev: Device to check.
	*/
	bool default_stop_ok(struct device *dev)
	{
	struct gpd_timing_data *td = &dev_gpd_data(dev)->td;
	unsigned long flags;
	s64 constraint_ns;

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

	spin_lock_irqsave(&dev->power.lock, flags);

	if (!td->constraint_changed) {
	bool ret = td->cached_stop_ok;

	spin_unlock_irqrestore(&dev->power.lock, flags);
	return ret;
	}
	td->constraint_changed = false;
	td->cached_stop_ok = false;
	td->effective_constraint_ns = -1;
	constraint_ns = __dev_pm_qos_read_value(dev);

	spin_unlock_irqrestore(&dev->power.lock, flags);

	if (constraint_ns < 0)
	return false;

	constraint_ns *= NSEC_PER_USEC;
	/*
	* We can walk the children without any additional locking, because
	* they all have been suspended at this point and their
	* effective_constraint_ns fields won't be modified in parallel with us.
	*/
	if (!dev->power.ignore_children)
	device_for_each_child(dev, &constraint_ns,
	dev_update_qos_constraint);

	if (constraint_ns > 0) {
	constraint_ns -= td->start_latency_ns;
	if (constraint_ns == 0)
	return false;
	}
	td->effective_constraint_ns = constraint_ns;
	td->cached_stop_ok = constraint_ns > td->stop_latency_ns \|\|
	constraint_ns == 0;
	/*
	* The children have been suspended already, so we don't need to take
	* their stop latencies into account here.
	*/
	return td->cached_stop_ok;
	}

	/**
	* default_power_down_ok - Default generic PM domain power off governor routine.
	* @pd: PM domain to check.
	*
	* This routine must be executed under the PM domain's lock.
	*/
	static bool default_power_down_ok(struct dev_pm_domain *pd)
	{
	struct generic_pm_domain *genpd = pd_to_genpd(pd);
	struct gpd_link *link;
	struct pm_domain_data *pdd;
	s64 min_off_time_ns;
	s64 off_on_time_ns;

	if (genpd->max_off_time_changed) {
	struct gpd_link *link;

	/*
	* We have to invalidate the cached results for the masters, so
	* use the observation that default_power_down_ok() is not
	* going to be called for any master until this instance
	* returns.
	*/
	list_for_each_entry(link, &genpd->slave_links, slave_node)
	link->master->max_off_time_changed = true;

	genpd->max_off_time_changed = false;
	genpd->cached_power_down_ok = false;
	genpd->max_off_time_ns = -1;
	} else {
	return genpd->cached_power_down_ok;
	}

	off_on_time_ns = genpd->power_off_latency_ns +
	genpd->power_on_latency_ns;
	/*
	* It doesn't make sense to remove power from the domain if saving
	* the state of all devices in it and the power off/power on operations
	* take too much time.
	*
	* All devices in this domain have been stopped already at this point.
	*/
	list_for_each_entry(pdd, &genpd->dev_list, list_node) {
	if (pdd->dev->driver)
	off_on_time_ns +=
	to_gpd_data(pdd)->td.save_state_latency_ns;
	}

	min_off_time_ns = -1;
	/*
	* Check if subdomains can be off for enough time.
	*
	* All subdomains have been powered off already at this point.
	*/
	list_for_each_entry(link, &genpd->master_links, master_node) {
	struct generic_pm_domain *sd = link->slave;
	s64 sd_max_off_ns = sd->max_off_time_ns;

	if (sd_max_off_ns < 0)
	continue;

	/*
	* Check if the subdomain is allowed to be off long enough for
	* the current domain to turn off and on (that's how much time
	* it will have to wait worst case).
	*/
	if (sd_max_off_ns <= off_on_time_ns)
	return false;

	if (min_off_time_ns > sd_max_off_ns \|\| min_off_time_ns < 0)
	min_off_time_ns = sd_max_off_ns;
	}

	/*
	* Check if the devices in the domain can be off enough time.
	*/
	list_for_each_entry(pdd, &genpd->dev_list, list_node) {
	struct gpd_timing_data *td;
	s64 constraint_ns;

	if (!pdd->dev->driver)
	continue;

	/*
	* Check if the device is allowed to be off long enough for the
	* domain to turn off and on (that's how much time it will
	* have to wait worst case).
	*/
	td = &to_gpd_data(pdd)->td;
	constraint_ns = td->effective_constraint_ns;
	/* default_stop_ok() need not be called before us. */
	if (constraint_ns < 0) {
	constraint_ns = dev_pm_qos_read_value(pdd->dev);
	constraint_ns *= NSEC_PER_USEC;
	}
	if (constraint_ns == 0)
	continue;

	/*
	* constraint_ns cannot be negative here, because the device has
	* been suspended.
	*/
	constraint_ns -= td->restore_state_latency_ns;
	if (constraint_ns <= off_on_time_ns)
	return false;

	if (min_off_time_ns > constraint_ns \|\| min_off_time_ns < 0)
	min_off_time_ns = constraint_ns;
	}

	genpd->cached_power_down_ok = true;

	/*
	* If the computed minimum device off time is negative, there are no
	* latency constraints, so the domain can spend arbitrary time in the
	* "off" state.
	*/
	if (min_off_time_ns < 0)
	return true;

	/*
	* The difference between the computed minimum subdomain or device off
	* time and the time needed to turn the domain on is the maximum
	* theoretical time this domain can spend in the "off" state.
	*/
	genpd->max_off_time_ns = min_off_time_ns - genpd->power_on_latency_ns;
	return true;
	}

	static bool always_on_power_down_ok(struct dev_pm_domain *domain)
	{
	return false;
	}

	#else /* !CONFIG_PM_RUNTIME */

	bool default_stop_ok(struct device *dev)
	{
	return false;
	}

	#define default_power_down_ok NULL
	#define always_on_power_down_ok NULL

	#endif /* !CONFIG_PM_RUNTIME */

	struct dev_power_governor simple_qos_governor = {
	.stop_ok = default_stop_ok,
	.power_down_ok = default_power_down_ok,
	};

	/**
	* pm_genpd_gov_always_on - A governor implementing an always-on policy
	*/
	struct dev_power_governor pm_domain_always_on_gov = {
	.power_down_ok = always_on_power_down_ok,
	.stop_ok = default_stop_ok,
	};