[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->suspend_latency_ns +
				td->resume_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;

		/*
		 * 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) {
2b1d88cd UH	80	constraint_ns -= td->suspend_latency_ns +
2b1d88cd UH	81	td->resume_latency_ns;
a5bef810 RW	82	if (constraint_ns == 0)
	83	return false;
	84	}
	85	td->effective_constraint_ns = constraint_ns;
a98f1b78 UH	86	td->cached_stop_ok = constraint_ns >= 0;
a98f1b78 UH	87
a5bef810 RW	88	/*
	89	* The children have been suspended already, so we don't need to take
	90	* their stop latencies into account here.
	91	*/
6ff7bb0d	92	return td->cached_stop_ok;
b02c999a RW	93	}
b02c999a RW	94
221e9b58 RW	95	/**
	96	* default_power_down_ok - Default generic PM domain power off governor routine.
	97	* @pd: PM domain to check.
	98	*
	99	* This routine must be executed under the PM domain's lock.
	100	*/
	101	static bool default_power_down_ok(struct dev_pm_domain *pd)
	102	{
	103	struct generic_pm_domain *genpd = pd_to_genpd(pd);
	104	struct gpd_link *link;
	105	struct pm_domain_data *pdd;
b723b0eb	106	s64 min_off_time_ns;
221e9b58	107	s64 off_on_time_ns;
221e9b58	108
6ff7bb0d RW	109	if (genpd->max_off_time_changed) {
	110	struct gpd_link *link;
	111
	112	/*
	113	* We have to invalidate the cached results for the masters, so
	114	* use the observation that default_power_down_ok() is not
	115	* going to be called for any master until this instance
	116	* returns.
	117	*/
	118	list_for_each_entry(link, &genpd->slave_links, slave_node)
	119	link->master->max_off_time_changed = true;
	120
	121	genpd->max_off_time_changed = false;
	122	genpd->cached_power_down_ok = false;
	123	genpd->max_off_time_ns = -1;
	124	} else {
	125	return genpd->cached_power_down_ok;
	126	}
	127
221e9b58 RW	128	off_on_time_ns = genpd->power_off_latency_ns +
221e9b58 RW	129	genpd->power_on_latency_ns;
221e9b58	130
b723b0eb	131	min_off_time_ns = -1;
221e9b58 RW	132	/*
	133	* Check if subdomains can be off for enough time.
	134	*
	135	* All subdomains have been powered off already at this point.
	136	*/
	137	list_for_each_entry(link, &genpd->master_links, master_node) {
	138	struct generic_pm_domain *sd = link->slave;
	139	s64 sd_max_off_ns = sd->max_off_time_ns;
	140
	141	if (sd_max_off_ns < 0)
	142	continue;
	143
221e9b58 RW	144	/*
	145	* Check if the subdomain is allowed to be off long enough for
	146	* the current domain to turn off and on (that's how much time
	147	* it will have to wait worst case).
	148	*/
	149	if (sd_max_off_ns <= off_on_time_ns)
	150	return false;
b723b0eb RW	151
	152	if (min_off_time_ns > sd_max_off_ns \|\| min_off_time_ns < 0)
	153	min_off_time_ns = sd_max_off_ns;
221e9b58 RW	154	}
	155
	156	/*
	157	* Check if the devices in the domain can be off enough time.
	158	*/
221e9b58 RW	159	list_for_each_entry(pdd, &genpd->dev_list, list_node) {
221e9b58 RW	160	struct gpd_timing_data *td;
dd8683e9	161	s64 constraint_ns;
221e9b58	162
dd8683e9 RW	163	/*
	164	* Check if the device is allowed to be off long enough for the
	165	* domain to turn off and on (that's how much time it will
	166	* have to wait worst case).
	167	*/
221e9b58	168	td = &to_gpd_data(pdd)->td;
dd8683e9 RW	169	constraint_ns = td->effective_constraint_ns;
	170	/* default_stop_ok() need not be called before us. */
	171	if (constraint_ns < 0) {
	172	constraint_ns = dev_pm_qos_read_value(pdd->dev);
	173	constraint_ns *= NSEC_PER_USEC;
	174	}
	175	if (constraint_ns == 0)
	176	continue;
221e9b58	177
221e9b58	178	/*
dd8683e9 RW	179	* constraint_ns cannot be negative here, because the device has
dd8683e9 RW	180	* been suspended.
221e9b58	181	*/
dd8683e9 RW	182	if (constraint_ns <= off_on_time_ns)
	183	return false;
	184
b723b0eb RW	185	if (min_off_time_ns > constraint_ns \|\| min_off_time_ns < 0)
b723b0eb RW	186	min_off_time_ns = constraint_ns;
221e9b58 RW	187	}
221e9b58 RW	188
6ff7bb0d RW	189	genpd->cached_power_down_ok = true;
6ff7bb0d RW	190
221e9b58	191	/*
dd8683e9 RW	192	* If the computed minimum device off time is negative, there are no
	193	* latency constraints, so the domain can spend arbitrary time in the
	194	* "off" state.
221e9b58	195	*/
b723b0eb	196	if (min_off_time_ns < 0)
dd8683e9	197	return true;
221e9b58 RW	198
221e9b58 RW	199	/*
b723b0eb RW	200	* The difference between the computed minimum subdomain or device off
	201	* time and the time needed to turn the domain on is the maximum
	202	* theoretical time this domain can spend in the "off" state.
221e9b58	203	*/
b723b0eb	204	genpd->max_off_time_ns = min_off_time_ns - genpd->power_on_latency_ns;
221e9b58 RW	205	return true;
	206	}
	207
925b44a2 MB	208	static bool always_on_power_down_ok(struct dev_pm_domain *domain)
	209	{
	210	return false;
	211	}
	212
e59a8db8 RW	213	struct dev_power_governor simple_qos_governor = {
	214	.stop_ok = default_stop_ok,
	215	.power_down_ok = default_power_down_ok,
	216	};
	217
925b44a2 MB	218	/**
	219	* pm_genpd_gov_always_on - A governor implementing an always-on policy
	220	*/
	221	struct dev_power_governor pm_domain_always_on_gov = {
	222	.power_down_ok = always_on_power_down_ok,
	223	.stop_ok = default_stop_ok,
	224	};