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: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h
index 222c3e01397c17674ea6811aaefc330c3a3077a1..57b93e3d8f294b1696aaf117d81f286fe5789c4c 100644 (file)
--- a/include/linux/pm_qos.h
+++ b/include/linux/pm_qos.h
@@ -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

diff --git a/kernel/power/qos.c b/kernel/power/qos.c
index 9568a2fe7c116155f6c6c2c4a3220cd58f78a32b..04e83fdfbe80c016d986adae9fe2fd36bc2ca8d7 100644 (file)
--- a/kernel/power/qos.c
+++ b/kernel/power/qos.c
@@ -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);