[people/ms/linux.git] / drivers / base / power / domain_governor.c

/*
 * 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>

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.
 */
static 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->save_state_latency_ns +
				td->stop_latency_ns +
				td->start_latency_ns +
				td->restore_state_latency_ns;
		if (constraint_ns == 0)
			return false;
	}
	td->effective_constraint_ns = constraint_ns;
	td->cached_stop_ok = 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;

	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.
		 */
		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;
}

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,
};
Commit	Line	Data
b02c999a RW	1	/*
	2	* drivers/base/power/domain_governor.c - Governors for device PM domains.
	3	*
	4	* Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
	5	*
	6	* This file is released under the GPLv2.
	7	*/
	8
b02c999a RW	9	#include <linux/kernel.h>
	10	#include <linux/pm_domain.h>
	11	#include <linux/pm_qos.h>
221e9b58	12	#include <linux/hrtimer.h>
b02c999a	13
a5bef810 RW	14	static int dev_update_qos_constraint(struct device dev, void data)
	15	{
	16	s64 *constraint_ns_p = data;
	17	s32 constraint_ns = -1;
	18
	19	if (dev->power.subsys_data && dev->power.subsys_data->domain_data)
	20	constraint_ns = dev_gpd_data(dev)->td.effective_constraint_ns;
	21
	22	if (constraint_ns < 0) {
	23	constraint_ns = dev_pm_qos_read_value(dev);
	24	constraint_ns *= NSEC_PER_USEC;
	25	}
	26	if (constraint_ns == 0)
	27	return 0;
	28
	29	/*
	30	* constraint_ns cannot be negative here, because the device has been
	31	* suspended.
	32	*/
	33	if (constraint_ns < constraint_ns_p \|\| constraint_ns_p == 0)
	34	*constraint_ns_p = constraint_ns;
	35
	36	return 0;
	37	}
	38
b02c999a RW	39	/**
	40	* default_stop_ok - Default PM domain governor routine for stopping devices.
	41	* @dev: Device to check.
	42	*/
0f574d4c	43	static bool default_stop_ok(struct device *dev)
b02c999a RW	44	{
b02c999a RW	45	struct gpd_timing_data *td = &dev_gpd_data(dev)->td;
6ff7bb0d	46	unsigned long flags;
a5bef810	47	s64 constraint_ns;
b02c999a RW	48
	49	dev_dbg(dev, "%s()\n", __func__);
	50
6ff7bb0d RW	51	spin_lock_irqsave(&dev->power.lock, flags);
	52
	53	if (!td->constraint_changed) {
	54	bool ret = td->cached_stop_ok;
	55
	56	spin_unlock_irqrestore(&dev->power.lock, flags);
	57	return ret;
	58	}
	59	td->constraint_changed = false;
	60	td->cached_stop_ok = false;
	61	td->effective_constraint_ns = -1;
	62	constraint_ns = __dev_pm_qos_read_value(dev);
	63
	64	spin_unlock_irqrestore(&dev->power.lock, flags);
	65
a5bef810 RW	66	if (constraint_ns < 0)
a5bef810 RW	67	return false;
b02c999a	68
a5bef810 RW	69	constraint_ns *= NSEC_PER_USEC;
	70	/*
	71	* We can walk the children without any additional locking, because
6ff7bb0d RW	72	* they all have been suspended at this point and their
6ff7bb0d RW	73	* effective_constraint_ns fields won't be modified in parallel with us.
a5bef810 RW	74	*/
	75	if (!dev->power.ignore_children)
	76	device_for_each_child(dev, &constraint_ns,
	77	dev_update_qos_constraint);
	78
	79	if (constraint_ns > 0) {
a98f1b78 UH	80	constraint_ns -= td->save_state_latency_ns +
	81	td->stop_latency_ns +
	82	td->start_latency_ns +
	83	td->restore_state_latency_ns;
a5bef810 RW	84	if (constraint_ns == 0)
	85	return false;
	86	}
	87	td->effective_constraint_ns = constraint_ns;
a98f1b78 UH	88	td->cached_stop_ok = constraint_ns >= 0;
a98f1b78 UH	89
a5bef810 RW	90	/*
	91	* The children have been suspended already, so we don't need to take
	92	* their stop latencies into account here.
	93	*/
6ff7bb0d	94	return td->cached_stop_ok;
b02c999a RW	95	}
b02c999a RW	96
221e9b58 RW	97	/**
	98	* default_power_down_ok - Default generic PM domain power off governor routine.
	99	* @pd: PM domain to check.
	100	*
	101	* This routine must be executed under the PM domain's lock.
	102	*/
	103	static bool default_power_down_ok(struct dev_pm_domain *pd)
	104	{
	105	struct generic_pm_domain *genpd = pd_to_genpd(pd);
	106	struct gpd_link *link;
	107	struct pm_domain_data *pdd;
b723b0eb	108	s64 min_off_time_ns;
221e9b58	109	s64 off_on_time_ns;
221e9b58	110
6ff7bb0d RW	111	if (genpd->max_off_time_changed) {
	112	struct gpd_link *link;
	113
	114	/*
	115	* We have to invalidate the cached results for the masters, so
	116	* use the observation that default_power_down_ok() is not
	117	* going to be called for any master until this instance
	118	* returns.
	119	*/
	120	list_for_each_entry(link, &genpd->slave_links, slave_node)
	121	link->master->max_off_time_changed = true;
	122
	123	genpd->max_off_time_changed = false;
	124	genpd->cached_power_down_ok = false;
	125	genpd->max_off_time_ns = -1;
	126	} else {
	127	return genpd->cached_power_down_ok;
	128	}
	129
221e9b58 RW	130	off_on_time_ns = genpd->power_off_latency_ns +
221e9b58 RW	131	genpd->power_on_latency_ns;
221e9b58	132
b723b0eb	133	min_off_time_ns = -1;
221e9b58 RW	134	/*
	135	* Check if subdomains can be off for enough time.
	136	*
	137	* All subdomains have been powered off already at this point.
	138	*/
	139	list_for_each_entry(link, &genpd->master_links, master_node) {
	140	struct generic_pm_domain *sd = link->slave;
	141	s64 sd_max_off_ns = sd->max_off_time_ns;
	142
	143	if (sd_max_off_ns < 0)
	144	continue;
	145
221e9b58 RW	146	/*
	147	* Check if the subdomain is allowed to be off long enough for
	148	* the current domain to turn off and on (that's how much time
	149	* it will have to wait worst case).
	150	*/
	151	if (sd_max_off_ns <= off_on_time_ns)
	152	return false;
b723b0eb RW	153
	154	if (min_off_time_ns > sd_max_off_ns \|\| min_off_time_ns < 0)
	155	min_off_time_ns = sd_max_off_ns;
221e9b58 RW	156	}
	157
	158	/*
	159	* Check if the devices in the domain can be off enough time.
	160	*/
221e9b58 RW	161	list_for_each_entry(pdd, &genpd->dev_list, list_node) {
221e9b58 RW	162	struct gpd_timing_data *td;
dd8683e9	163	s64 constraint_ns;
221e9b58	164
dd8683e9	165	if (!pdd->dev->driver)
221e9b58 RW	166	continue;
221e9b58 RW	167
dd8683e9 RW	168	/*
	169	* Check if the device is allowed to be off long enough for the
	170	* domain to turn off and on (that's how much time it will
	171	* have to wait worst case).
	172	*/
221e9b58	173	td = &to_gpd_data(pdd)->td;
dd8683e9 RW	174	constraint_ns = td->effective_constraint_ns;
	175	/* default_stop_ok() need not be called before us. */
	176	if (constraint_ns < 0) {
	177	constraint_ns = dev_pm_qos_read_value(pdd->dev);
	178	constraint_ns *= NSEC_PER_USEC;
	179	}
	180	if (constraint_ns == 0)
	181	continue;
221e9b58	182
221e9b58	183	/*
dd8683e9 RW	184	* constraint_ns cannot be negative here, because the device has
dd8683e9 RW	185	* been suspended.
221e9b58	186	*/
dd8683e9 RW	187	if (constraint_ns <= off_on_time_ns)
	188	return false;
	189
b723b0eb RW	190	if (min_off_time_ns > constraint_ns \|\| min_off_time_ns < 0)
b723b0eb RW	191	min_off_time_ns = constraint_ns;
221e9b58 RW	192	}
221e9b58 RW	193
6ff7bb0d RW	194	genpd->cached_power_down_ok = true;
6ff7bb0d RW	195
221e9b58	196	/*
dd8683e9 RW	197	* If the computed minimum device off time is negative, there are no
	198	* latency constraints, so the domain can spend arbitrary time in the
	199	* "off" state.
221e9b58	200	*/
b723b0eb	201	if (min_off_time_ns < 0)
dd8683e9	202	return true;
221e9b58 RW	203
221e9b58 RW	204	/*
b723b0eb RW	205	* The difference between the computed minimum subdomain or device off
	206	* time and the time needed to turn the domain on is the maximum
	207	* theoretical time this domain can spend in the "off" state.
221e9b58	208	*/
b723b0eb	209	genpd->max_off_time_ns = min_off_time_ns - genpd->power_on_latency_ns;
221e9b58 RW	210	return true;
	211	}
	212
925b44a2 MB	213	static bool always_on_power_down_ok(struct dev_pm_domain *domain)
	214	{
	215	return false;
	216	}
	217
e59a8db8 RW	218	struct dev_power_governor simple_qos_governor = {
	219	.stop_ok = default_stop_ok,
	220	.power_down_ok = default_power_down_ok,
	221	};
	222
925b44a2 MB	223	/**
	224	* pm_genpd_gov_always_on - A governor implementing an always-on policy
	225	*/
	226	struct dev_power_governor pm_domain_always_on_gov = {
	227	.power_down_ok = always_on_power_down_ok,
	228	.stop_ok = default_stop_ok,
	229	};