[deliverable/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_suspend_ok - Default PM domain governor routine to suspend devices.
 * @dev: Device to check.
 */
static bool default_suspend_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_suspend_ok;

		spin_unlock_irqrestore(&dev->power.lock, flags);
		return ret;
	}
	td->constraint_changed = false;
	td->cached_suspend_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_suspend_ok = constraint_ns >= 0;

	/*
	 * The children have been suspended already, so we don't need to take
	 * their suspend latencies into account here.
	 */
	return td->cached_suspend_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,
				     unsigned int state)
{
	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;

	off_on_time_ns = genpd->states[state].power_off_latency_ns +
		genpd->states[state].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_suspend_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;
	}

	/*
	 * 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->states[state].power_on_latency_ns;
	return true;
}

static bool default_power_down_ok(struct dev_pm_domain *pd)
{
	struct generic_pm_domain *genpd = pd_to_genpd(pd);
	struct gpd_link *link;

	if (!genpd->max_off_time_changed)
		return genpd->cached_power_down_ok;

	/*
	 * 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_ns = -1;
	genpd->max_off_time_changed = false;
	genpd->cached_power_down_ok = true;
	genpd->state_idx = genpd->state_count - 1;

	/* Find a state to power down to, starting from the deepest. */
	while (!__default_power_down_ok(pd, genpd->state_idx)) {
		if (genpd->state_idx == 0) {
			genpd->cached_power_down_ok = false;
			break;
		}
		genpd->state_idx--;
	}

	return genpd->cached_power_down_ok;
}

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

struct dev_power_governor simple_qos_governor = {
	.suspend_ok = default_suspend_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,
	.suspend_ok = default_suspend_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	39	/**
9df3921e	40	* default_suspend_ok - Default PM domain governor routine to suspend devices.
b02c999a RW	41	* @dev: Device to check.
b02c999a RW	42	*/
9df3921e	43	static bool default_suspend_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) {
9df3921e	54	bool ret = td->cached_suspend_ok;
6ff7bb0d RW	55
	56	spin_unlock_irqrestore(&dev->power.lock, flags);
	57	return ret;
	58	}
	59	td->constraint_changed = false;
9df3921e	60	td->cached_suspend_ok = false;
6ff7bb0d RW	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;
9df3921e	86	td->cached_suspend_ok = constraint_ns >= 0;
a98f1b78	87
a5bef810 RW	88	/*
a5bef810 RW	89	* The children have been suspended already, so we don't need to take
9df3921e	90	* their suspend latencies into account here.
a5bef810	91	*/
9df3921e	92	return td->cached_suspend_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	*/
fc5cbf0c AH	101	static bool __default_power_down_ok(struct dev_pm_domain *pd,
fc5cbf0c AH	102	unsigned int state)
221e9b58 RW	103	{
	104	struct generic_pm_domain *genpd = pd_to_genpd(pd);
	105	struct gpd_link *link;
	106	struct pm_domain_data *pdd;
b723b0eb	107	s64 min_off_time_ns;
221e9b58	108	s64 off_on_time_ns;
221e9b58	109
fc5cbf0c AH	110	off_on_time_ns = genpd->states[state].power_off_latency_ns +
fc5cbf0c AH	111	genpd->states[state].power_on_latency_ns;
6ff7bb0d	112
221e9b58	113
b723b0eb	114	min_off_time_ns = -1;
221e9b58 RW	115	/*
	116	* Check if subdomains can be off for enough time.
	117	*
	118	* All subdomains have been powered off already at this point.
	119	*/
	120	list_for_each_entry(link, &genpd->master_links, master_node) {
	121	struct generic_pm_domain *sd = link->slave;
	122	s64 sd_max_off_ns = sd->max_off_time_ns;
	123
	124	if (sd_max_off_ns < 0)
	125	continue;
	126
221e9b58 RW	127	/*
	128	* Check if the subdomain is allowed to be off long enough for
	129	* the current domain to turn off and on (that's how much time
	130	* it will have to wait worst case).
	131	*/
	132	if (sd_max_off_ns <= off_on_time_ns)
	133	return false;
b723b0eb RW	134
	135	if (min_off_time_ns > sd_max_off_ns \|\| min_off_time_ns < 0)
	136	min_off_time_ns = sd_max_off_ns;
221e9b58 RW	137	}
	138
	139	/*
	140	* Check if the devices in the domain can be off enough time.
	141	*/
221e9b58 RW	142	list_for_each_entry(pdd, &genpd->dev_list, list_node) {
221e9b58 RW	143	struct gpd_timing_data *td;
dd8683e9	144	s64 constraint_ns;
221e9b58	145
dd8683e9 RW	146	/*
	147	* Check if the device is allowed to be off long enough for the
	148	* domain to turn off and on (that's how much time it will
	149	* have to wait worst case).
	150	*/
221e9b58	151	td = &to_gpd_data(pdd)->td;
dd8683e9	152	constraint_ns = td->effective_constraint_ns;
9df3921e	153	/* default_suspend_ok() need not be called before us. */
dd8683e9 RW	154	if (constraint_ns < 0) {
	155	constraint_ns = dev_pm_qos_read_value(pdd->dev);
	156	constraint_ns *= NSEC_PER_USEC;
	157	}
	158	if (constraint_ns == 0)
	159	continue;
221e9b58	160
221e9b58	161	/*
dd8683e9 RW	162	* constraint_ns cannot be negative here, because the device has
dd8683e9 RW	163	* been suspended.
221e9b58	164	*/
dd8683e9 RW	165	if (constraint_ns <= off_on_time_ns)
	166	return false;
	167
b723b0eb RW	168	if (min_off_time_ns > constraint_ns \|\| min_off_time_ns < 0)
b723b0eb RW	169	min_off_time_ns = constraint_ns;
221e9b58 RW	170	}
	171
	172	/*
dd8683e9 RW	173	* If the computed minimum device off time is negative, there are no
	174	* latency constraints, so the domain can spend arbitrary time in the
	175	* "off" state.
221e9b58	176	*/
b723b0eb	177	if (min_off_time_ns < 0)
dd8683e9	178	return true;
221e9b58 RW	179
221e9b58 RW	180	/*
b723b0eb RW	181	* The difference between the computed minimum subdomain or device off
	182	* time and the time needed to turn the domain on is the maximum
	183	* theoretical time this domain can spend in the "off" state.
221e9b58	184	*/
fc5cbf0c AH	185	genpd->max_off_time_ns = min_off_time_ns -
fc5cbf0c AH	186	genpd->states[state].power_on_latency_ns;
221e9b58 RW	187	return true;
	188	}
	189
fc5cbf0c AH	190	static bool default_power_down_ok(struct dev_pm_domain *pd)
	191	{
	192	struct generic_pm_domain *genpd = pd_to_genpd(pd);
	193	struct gpd_link *link;
	194
	195	if (!genpd->max_off_time_changed)
	196	return genpd->cached_power_down_ok;
	197
	198	/*
	199	* We have to invalidate the cached results for the masters, so
	200	* use the observation that default_power_down_ok() is not
	201	* going to be called for any master until this instance
	202	* returns.
	203	*/
	204	list_for_each_entry(link, &genpd->slave_links, slave_node)
	205	link->master->max_off_time_changed = true;
	206
	207	genpd->max_off_time_ns = -1;
	208	genpd->max_off_time_changed = false;
	209	genpd->cached_power_down_ok = true;
	210	genpd->state_idx = genpd->state_count - 1;
	211
	212	/* Find a state to power down to, starting from the deepest. */
	213	while (!__default_power_down_ok(pd, genpd->state_idx)) {
	214	if (genpd->state_idx == 0) {
	215	genpd->cached_power_down_ok = false;
	216	break;
	217	}
	218	genpd->state_idx--;
	219	}
	220
	221	return genpd->cached_power_down_ok;
	222	}
	223
925b44a2 MB	224	static bool always_on_power_down_ok(struct dev_pm_domain *domain)
	225	{
	226	return false;
	227	}
	228
e59a8db8	229	struct dev_power_governor simple_qos_governor = {
9df3921e	230	.suspend_ok = default_suspend_ok,
e59a8db8 RW	231	.power_down_ok = default_power_down_ok,
	232	};
	233
925b44a2 MB	234	/**
	235	* pm_genpd_gov_always_on - A governor implementing an always-on policy
	236	*/
	237	struct dev_power_governor pm_domain_always_on_gov = {
	238	.power_down_ok = always_on_power_down_ok,
9df3921e	239	.suspend_ok = default_suspend_ok,
925b44a2	240	};