Commit 77751a46 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
Browse files

PM: QoS: Introduce frequency QoS 



Introduce frequency QoS, based on the "raw" low-level PM QoS, to
represent min and max frequency requests and aggregate constraints.

The min and max frequency requests are to be represented by
struct freq_qos_request objects and the aggregate constraints are to
be represented by struct freq_constraints objects.  The latter are
expected to be initialized with the help of freq_constraints_init().

The freq_qos_read_value() helper is defined to retrieve the aggregate
constraints values from a given struct freq_constraints object and
there are the freq_qos_add_request(), freq_qos_update_request() and
freq_qos_remove_request() helpers to manipulate the min and max
frequency requests.  It is assumed that the the helpers will not
run concurrently with each other for the same struct freq_qos_request
object, so if that may be the case, their uses must ensure proper
synchronization between them (e.g. through locking).

In addition, freq_qos_add_notifier() and freq_qos_remove_notifier()
are provided to add and remove notifiers that will trigger on aggregate
constraint changes to and from a given struct freq_constraints object,
respectively.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
parent 7d194c21

include/linux/pm_qos.h

+44 −0
Original line number Diff line number Diff line
@@ -267,4 +267,48 @@ static inline s32 dev_pm_qos_raw_resume_latency(struct device *dev) 
}

#endif



#define FREQ_QOS_MIN_DEFAULT_VALUE	0

#define FREQ_QOS_MAX_DEFAULT_VALUE	(-1)



enum freq_qos_req_type {

	FREQ_QOS_MIN = 1,

	FREQ_QOS_MAX,

};



struct freq_constraints {

	struct pm_qos_constraints min_freq;

	struct blocking_notifier_head min_freq_notifiers;

	struct pm_qos_constraints max_freq;

	struct blocking_notifier_head max_freq_notifiers;

};



struct freq_qos_request {

	enum freq_qos_req_type type;

	struct plist_node pnode;

	struct freq_constraints *qos;

};



static inline int freq_qos_request_active(struct freq_qos_request *req)

{

	return !IS_ERR_OR_NULL(req->qos);

}



void freq_constraints_init(struct freq_constraints *qos);



s32 freq_qos_read_value(struct freq_constraints *qos,

			enum freq_qos_req_type type);



int freq_qos_add_request(struct freq_constraints *qos,

			 struct freq_qos_request *req,

			 enum freq_qos_req_type type, s32 value);

int freq_qos_update_request(struct freq_qos_request *req, s32 new_value);

int freq_qos_remove_request(struct freq_qos_request *req);



int freq_qos_add_notifier(struct freq_constraints *qos,

			  enum freq_qos_req_type type,

			  struct notifier_block *notifier);

int freq_qos_remove_notifier(struct freq_constraints *qos,

			     enum freq_qos_req_type type,

			     struct notifier_block *notifier);



#endif

kernel/power/qos.c

+240 −0
Original line number Diff line number Diff line
@@ -650,3 +650,243 @@ static int __init pm_qos_power_init(void) 
}



late_initcall(pm_qos_power_init);



/* Definitions related to the frequency QoS below. */



/**

 * freq_constraints_init - Initialize frequency QoS constraints.

 * @qos: Frequency QoS constraints to initialize.

 */

void freq_constraints_init(struct freq_constraints *qos)

{

	struct pm_qos_constraints *c;



	c = &qos->min_freq;

	plist_head_init(&c->list);

	c->target_value = FREQ_QOS_MIN_DEFAULT_VALUE;

	c->default_value = FREQ_QOS_MIN_DEFAULT_VALUE;

	c->no_constraint_value = FREQ_QOS_MIN_DEFAULT_VALUE;

	c->type = PM_QOS_MAX;

	c->notifiers = &qos->min_freq_notifiers;

	BLOCKING_INIT_NOTIFIER_HEAD(c->notifiers);



	c = &qos->max_freq;

	plist_head_init(&c->list);

	c->target_value = FREQ_QOS_MAX_DEFAULT_VALUE;

	c->default_value = FREQ_QOS_MAX_DEFAULT_VALUE;

	c->no_constraint_value = FREQ_QOS_MAX_DEFAULT_VALUE;

	c->type = PM_QOS_MIN;

	c->notifiers = &qos->max_freq_notifiers;

	BLOCKING_INIT_NOTIFIER_HEAD(c->notifiers);

}



/**

 * freq_qos_read_value - Get frequency QoS constraint for a given list.

 * @qos: Constraints to evaluate.

 * @type: QoS request type.

 */

s32 freq_qos_read_value(struct freq_constraints *qos,

			enum freq_qos_req_type type)

{

	s32 ret;



	switch (type) {

	case FREQ_QOS_MIN:

		ret = IS_ERR_OR_NULL(qos) ?

			FREQ_QOS_MIN_DEFAULT_VALUE :

			pm_qos_read_value(&qos->min_freq);

		break;

	case FREQ_QOS_MAX:

		ret = IS_ERR_OR_NULL(qos) ?

			FREQ_QOS_MAX_DEFAULT_VALUE :

			pm_qos_read_value(&qos->max_freq);

		break;

	default:

		WARN_ON(1);

		ret = 0;

	}



	return ret;

}



/**

 * freq_qos_apply - Add/modify/remove frequency QoS request.

 * @req: Constraint request to apply.

 * @action: Action to perform (add/update/remove).

 * @value: Value to assign to the QoS request.

 */

static int freq_qos_apply(struct freq_qos_request *req,

			  enum pm_qos_req_action action, s32 value)

{

	int ret;



	switch(req->type) {

	case FREQ_QOS_MIN:

		ret = pm_qos_update_target(&req->qos->min_freq, &req->pnode,

					   action, value);

		break;

	case FREQ_QOS_MAX:

		ret = pm_qos_update_target(&req->qos->max_freq, &req->pnode,

					   action, value);

		break;

	default:

		ret = -EINVAL;

	}



	return ret;

}



/**

 * freq_qos_add_request - Insert new frequency QoS request into a given list.

 * @qos: Constraints to update.

 * @req: Preallocated request object.

 * @type: Request type.

 * @value: Request value.

 *

 * Insert a new entry into the @qos list of requests, recompute the effective

 * QoS constraint value for that list and initialize the @req object.  The

 * caller needs to save that object for later use in updates and removal.

 *

 * Return 1 if the effective constraint value has changed, 0 if the effective

 * constraint value has not changed, or a negative error code on failures.

 */

int freq_qos_add_request(struct freq_constraints *qos,

			 struct freq_qos_request *req,

			 enum freq_qos_req_type type, s32 value)

{

	int ret;



	if (IS_ERR_OR_NULL(qos) || !req)

		return -EINVAL;



	if (WARN(freq_qos_request_active(req),

		 "%s() called for active request\n", __func__))

		return -EINVAL;



	req->qos = qos;

	req->type = type;

	ret = freq_qos_apply(req, PM_QOS_ADD_REQ, value);

	if (ret < 0) {

		req->qos = NULL;

		req->type = 0;

	}



	return ret;

}

EXPORT_SYMBOL_GPL(freq_qos_add_request);



/**

 * freq_qos_update_request - Modify existing frequency QoS request.

 * @req: Request to modify.

 * @new_value: New request value.

 *

 * Update an existing frequency QoS request along with the effective constraint

 * value for the list of requests it belongs to.

 *

 * Return 1 if the effective constraint value has changed, 0 if the effective

 * constraint value has not changed, or a negative error code on failures.

 */

int freq_qos_update_request(struct freq_qos_request *req, s32 new_value)

{

	if (!req)

		return -EINVAL;



	if (WARN(!freq_qos_request_active(req),

		 "%s() called for unknown object\n", __func__))

		return -EINVAL;



	if (req->pnode.prio == new_value)

		return 0;



	return freq_qos_apply(req, PM_QOS_UPDATE_REQ, new_value);

}

EXPORT_SYMBOL_GPL(freq_qos_update_request);



/**

 * freq_qos_remove_request - Remove frequency QoS request from its list.

 * @req: Request to remove.

 *

 * Remove the given frequency QoS request from the list of constraints it

 * belongs to and recompute the effective constraint value for that list.

 *

 * Return 1 if the effective constraint value has changed, 0 if the effective

 * constraint value has not changed, or a negative error code on failures.

 */

int freq_qos_remove_request(struct freq_qos_request *req)

{

	if (!req)

		return -EINVAL;



	if (WARN(!freq_qos_request_active(req),

		 "%s() called for unknown object\n", __func__))

		return -EINVAL;



	return freq_qos_apply(req, PM_QOS_REMOVE_REQ, PM_QOS_DEFAULT_VALUE);

}

EXPORT_SYMBOL_GPL(freq_qos_remove_request);



/**

 * freq_qos_add_notifier - Add frequency QoS change notifier.

 * @qos: List of requests to add the notifier to.

 * @type: Request type.

 * @notifier: Notifier block to add.

 */

int freq_qos_add_notifier(struct freq_constraints *qos,

			  enum freq_qos_req_type type,

			  struct notifier_block *notifier)

{

	int ret;



	if (IS_ERR_OR_NULL(qos) || !notifier)

		return -EINVAL;



	switch (type) {

	case FREQ_QOS_MIN:

		ret = blocking_notifier_chain_register(qos->min_freq.notifiers,

						       notifier);

		break;

	case FREQ_QOS_MAX:

		ret = blocking_notifier_chain_register(qos->max_freq.notifiers,

						       notifier);

		break;

	default:

		WARN_ON(1);

		ret = -EINVAL;

	}



	return ret;

}

EXPORT_SYMBOL_GPL(freq_qos_add_notifier);



/**

 * freq_qos_remove_notifier - Remove frequency QoS change notifier.

 * @qos: List of requests to remove the notifier from.

 * @type: Request type.

 * @notifier: Notifier block to remove.

 */

int freq_qos_remove_notifier(struct freq_constraints *qos,

			     enum freq_qos_req_type type,

			     struct notifier_block *notifier)

{

	int ret;



	if (IS_ERR_OR_NULL(qos) || !notifier)

		return -EINVAL;



	switch (type) {

	case FREQ_QOS_MIN:

		ret = blocking_notifier_chain_unregister(qos->min_freq.notifiers,

							 notifier);

		break;

	case FREQ_QOS_MAX:

		ret = blocking_notifier_chain_unregister(qos->max_freq.notifiers,

							 notifier);

		break;

	default:

		WARN_ON(1);

		ret = -EINVAL;

	}



	return ret;

}

EXPORT_SYMBOL_GPL(freq_qos_remove_notifier);

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