PM QoS: Add global notification mechanism for device constraints

Add a global notification chain that gets called upon changes to the aggregated constraint value for any device. The notification callbacks are passing the full constraint request data in order for the callees to have access to it. The current use is for the platform low-level code to access the target device of the constraint. Signed-off-by: Jean Pihet <j-pihet@ti.com> Reviewed-by: Kevin Hilman <khilman@ti.com> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

PM QoS: Add global notification mechanism for device constraints
Add a global notification chain that gets called upon changes to the aggregated constraint value for any device. The notification callbacks are passing the full constraint request data in order for the callees to have access to it. The current use is for the platform low-level code to access the target device of the constraint. Signed-off-by: Jean Pihet <j-pihet@ti.com> Reviewed-by: Kevin Hilman <khilman@ti.com> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Jean Pihet · Rafael J. Wysocki
1 parent 91ff4cb803
Showing 3 changed files with 87 additions and 15 deletions Side-by-side Diff
drivers/base/power/qos.c
include/linux/pm_qos.h
kernel/power/qos.c
@@ -17,6 +17,12 @@
  *
  * This QoS design is best effort based. Dependents register their QoS needs.
  * Watchers register to keep track of the current QoS needs of the system.
+ * Watchers can register different types of notification callbacks:
+ *  . a per-device notification callback using the dev_pm_qos_*_notifier API.
+ *    The notification chain data is stored in the per-device constraint
+ *    data struct.
+ *  . a system-wide notification callback using the dev_pm_qos_*_global_notifier
+ *    API. The notification chain data is stored in a static variable.
  *
  * Note about the per-device constraint data struct allocation:
  * . The per-device constraints data struct ptr is tored into the device
  
@@ -45,8 +51,38 @@
  
  
 static DEFINE_MUTEX(dev_pm_qos_mtx);
+static BLOCKING_NOTIFIER_HEAD(dev_pm_notifiers);
  
 /*
+ * apply_constraint
+ * @req: constraint request to apply
+ * @action: action to perform add/update/remove, of type enum pm_qos_req_action
+ * @value: defines the qos request
+ *
+ * Internal function to update the constraints list using the PM QoS core
+ * code and if needed call the per-device and the global notification
+ * callbacks
+ */
+static int apply_constraint(struct dev_pm_qos_request *req,
+			    enum pm_qos_req_action action, int value)
+{
+	int ret, curr_value;
+
+	ret = pm_qos_update_target(req->dev->power.constraints,
+				   &req->node, action, value);
+
+	if (ret) {
+		/* Call the global callbacks if needed */
+		curr_value = pm_qos_read_value(req->dev->power.constraints);
+		blocking_notifier_call_chain(&dev_pm_notifiers,
+					     (unsigned long)curr_value,
+					     req);
+	}
+
+	return ret;
+}
+
+/*
  * dev_pm_qos_constraints_allocate
  * @dev: device to allocate data for
  *
  
@@ -111,12 +147,11 @@
 					  &dev->power.constraints->list,
 					  node) {
 			/*
-			 * Update constraints list and call the per-device
+			 * Update constraints list and call the notification
 			 * callbacks if needed
 			 */
-			pm_qos_update_target(req->dev->power.constraints,
-					   &req->node, PM_QOS_REMOVE_REQ,
-					   PM_QOS_DEFAULT_VALUE);
+			apply_constraint(req, PM_QOS_REMOVE_REQ,
+					 PM_QOS_DEFAULT_VALUE);
 			memset(req, 0, sizeof(*req));
 		}
  
@@ -147,7 +182,7 @@
  * removed from the system
  */
 int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,
-			    s32 value)
+			   s32 value)
 {
 	int ret = 0;
  
@@ -178,8 +213,7 @@
 		ret = dev_pm_qos_constraints_allocate(dev);
  
 	if (!ret)
-		ret = pm_qos_update_target(dev->power.constraints, &req->node,
-					   PM_QOS_ADD_REQ, value);
+		ret = apply_constraint(req, PM_QOS_ADD_REQ, value);
  
 out:
 	mutex_unlock(&dev_pm_qos_mtx);
@@ -220,10 +254,8 @@
  
 	if (req->dev->power.constraints_state == DEV_PM_QOS_ALLOCATED) {
 		if (new_value != req->node.prio)
-			ret = pm_qos_update_target(req->dev->power.constraints,
-						   &req->node,
-						   PM_QOS_UPDATE_REQ,
-						   new_value);
+			ret = apply_constraint(req, PM_QOS_UPDATE_REQ,
+					       new_value);
 	} else {
 		/* Return if the device has been removed */
 		ret = -ENODEV;
@@ -262,9 +294,8 @@
 	mutex_lock(&dev_pm_qos_mtx);
  
 	if (req->dev->power.constraints_state == DEV_PM_QOS_ALLOCATED) {
-		ret = pm_qos_update_target(req->dev->power.constraints,
-					   &req->node, PM_QOS_REMOVE_REQ,
-					   PM_QOS_DEFAULT_VALUE);
+		ret = apply_constraint(req, PM_QOS_REMOVE_REQ,
+				       PM_QOS_DEFAULT_VALUE);
 		memset(req, 0, sizeof(*req));
 	} else {
 		/* Return if the device has been removed */
@@ -336,4 +367,34 @@
 	return retval;
 }
 EXPORT_SYMBOL_GPL(dev_pm_qos_remove_notifier);
+
+/**
+ * dev_pm_qos_add_global_notifier - sets notification entry for changes to
+ * target value of the PM QoS constraints for any device
+ *
+ * @notifier: notifier block managed by caller.
+ *
+ * Will register the notifier into a notification chain that gets called
+ * upon changes to the target value for any device.
+ */
+int dev_pm_qos_add_global_notifier(struct notifier_block *notifier)
+{
+	return blocking_notifier_chain_register(&dev_pm_notifiers, notifier);
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_add_global_notifier);
+
+/**
+ * dev_pm_qos_remove_global_notifier - deletes notification for changes to
+ * target value of PM QoS constraints for any device
+ *
+ * @notifier: notifier block to be removed.
+ *
+ * Will remove the notifier from the notification chain that gets called
+ * upon changes to the target value for any device.
+ */
+int dev_pm_qos_remove_global_notifier(struct notifier_block *notifier)
+{
+	return blocking_notifier_chain_unregister(&dev_pm_notifiers, notifier);
+}
+EXPORT_SYMBOL_GPL(dev_pm_qos_remove_global_notifier);
@@ -75,6 +75,7 @@
 int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier);
 int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier);
 int pm_qos_request_active(struct pm_qos_request *req);
+s32 pm_qos_read_value(struct pm_qos_constraints *c);
  
 int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,
 			   s32 value);
@@ -84,6 +85,8 @@
 			    struct notifier_block *notifier);
 int dev_pm_qos_remove_notifier(struct device *dev,
 			       struct notifier_block *notifier);
+int dev_pm_qos_add_global_notifier(struct notifier_block *notifier);
+int dev_pm_qos_remove_global_notifier(struct notifier_block *notifier);
 void dev_pm_qos_constraints_init(struct device *dev);
 void dev_pm_qos_constraints_destroy(struct device *dev);
 #else
@@ -111,6 +114,8 @@
 			{ return 0; }
 static inline int pm_qos_request_active(struct pm_qos_request *req)
 			{ return 0; }
+static inline s32 pm_qos_read_value(struct pm_qos_constraints *c)
+			{ return 0; }
  
 static inline int dev_pm_qos_add_request(struct device *dev,
 					 struct dev_pm_qos_request *req,
@@ -126,6 +131,12 @@
 			{ return 0; }
 static inline int dev_pm_qos_remove_notifier(struct device *dev,
 					     struct notifier_block *notifier)
+			{ return 0; }
+static inline int dev_pm_qos_add_global_notifier(
+					struct notifier_block *notifier)
+			{ return 0; }
+static inline int dev_pm_qos_remove_global_notifier(
+					struct notifier_block *notifier)
 			{ return 0; }
 static inline void dev_pm_qos_constraints_init(struct device *dev)
 			{ return; }
@@ -140,7 +140,7 @@
 	}
 }
  
-static inline s32 pm_qos_read_value(struct pm_qos_constraints *c)
+s32 pm_qos_read_value(struct pm_qos_constraints *c)
 {
 	return c->target_value;
 }
...	...	@@ -17,6 +17,12 @@
17	17	*
18	18	* This QoS design is best effort based. Dependents register their QoS needs.
19	19	* Watchers register to keep track of the current QoS needs of the system.
	20	+ * Watchers can register different types of notification callbacks:
	21	+ * . a per-device notification callback using the dev_pm_qos_*_notifier API.
	22	+ * The notification chain data is stored in the per-device constraint
	23	+ * data struct.
	24	+ * . a system-wide notification callback using the dev_pm_qos_*_global_notifier
	25	+ * API. The notification chain data is stored in a static variable.
20	26	*
21	27	* Note about the per-device constraint data struct allocation:
22	28	* . The per-device constraints data struct ptr is tored into the device
23	29
...	...	@@ -45,8 +51,38 @@
45	51
46	52
47	53	static DEFINE_MUTEX(dev_pm_qos_mtx);
	54	+static BLOCKING_NOTIFIER_HEAD(dev_pm_notifiers);
48	55
49	56	/*
	57	+ * apply_constraint
	58	+ * @req: constraint request to apply
	59	+ * @action: action to perform add/update/remove, of type enum pm_qos_req_action
	60	+ * @value: defines the qos request
	61	+ *
	62	+ * Internal function to update the constraints list using the PM QoS core
	63	+ * code and if needed call the per-device and the global notification
	64	+ * callbacks
	65	+ */
	66	+static int apply_constraint(struct dev_pm_qos_request *req,
	67	+ enum pm_qos_req_action action, int value)
	68	+{
	69	+ int ret, curr_value;
	70	+
	71	+ ret = pm_qos_update_target(req->dev->power.constraints,
	72	+ &req->node, action, value);
	73	+
	74	+ if (ret) {
	75	+ /* Call the global callbacks if needed */
	76	+ curr_value = pm_qos_read_value(req->dev->power.constraints);
	77	+ blocking_notifier_call_chain(&dev_pm_notifiers,
	78	+ (unsigned long)curr_value,
	79	+ req);
	80	+ }
	81	+
	82	+ return ret;
	83	+}
	84	+
	85	+/*
50	86	* dev_pm_qos_constraints_allocate
51	87	* @dev: device to allocate data for
52	88	*
53	89
...	...	@@ -111,12 +147,11 @@
111	147	&dev->power.constraints->list,
112	148	node) {
113	149	/*
114		- * Update constraints list and call the per-device
	150	+ * Update constraints list and call the notification
115	151	* callbacks if needed
116	152	*/
117		- pm_qos_update_target(req->dev->power.constraints,
118		- &req->node, PM_QOS_REMOVE_REQ,
119		- PM_QOS_DEFAULT_VALUE);
	153	+ apply_constraint(req, PM_QOS_REMOVE_REQ,
	154	+ PM_QOS_DEFAULT_VALUE);
120	155	memset(req, 0, sizeof(*req));
121	156	}
122	157
...	...	@@ -147,7 +182,7 @@
147	182	* removed from the system
148	183	*/
149	184	int dev_pm_qos_add_request(struct device dev, struct dev_pm_qos_request req,
150		- s32 value)
	185	+ s32 value)
151	186	{
152	187	int ret = 0;
153	188
...	...	@@ -178,8 +213,7 @@
178	213	ret = dev_pm_qos_constraints_allocate(dev);
179	214
180	215	if (!ret)
181		- ret = pm_qos_update_target(dev->power.constraints, &req->node,
182		- PM_QOS_ADD_REQ, value);
	216	+ ret = apply_constraint(req, PM_QOS_ADD_REQ, value);
183	217
184	218	out:
185	219	mutex_unlock(&dev_pm_qos_mtx);
...	...	@@ -220,10 +254,8 @@
220	254
221	255	if (req->dev->power.constraints_state == DEV_PM_QOS_ALLOCATED) {
222	256	if (new_value != req->node.prio)
223		- ret = pm_qos_update_target(req->dev->power.constraints,
224		- &req->node,
225		- PM_QOS_UPDATE_REQ,
226		- new_value);
	257	+ ret = apply_constraint(req, PM_QOS_UPDATE_REQ,
	258	+ new_value);
227	259	} else {
228	260	/* Return if the device has been removed */
229	261	ret = -ENODEV;
...	...	@@ -262,9 +294,8 @@
262	294	mutex_lock(&dev_pm_qos_mtx);
263	295
264	296	if (req->dev->power.constraints_state == DEV_PM_QOS_ALLOCATED) {
265		- ret = pm_qos_update_target(req->dev->power.constraints,
266		- &req->node, PM_QOS_REMOVE_REQ,
267		- PM_QOS_DEFAULT_VALUE);
	297	+ ret = apply_constraint(req, PM_QOS_REMOVE_REQ,
	298	+ PM_QOS_DEFAULT_VALUE);
268	299	memset(req, 0, sizeof(*req));
269	300	} else {
270	301	/* Return if the device has been removed */
...	...	@@ -336,4 +367,34 @@
336	367	return retval;
337	368	}
338	369	EXPORT_SYMBOL_GPL(dev_pm_qos_remove_notifier);
	370	+
	371	+/**
	372	+ * dev_pm_qos_add_global_notifier - sets notification entry for changes to
	373	+ * target value of the PM QoS constraints for any device
	374	+ *
	375	+ * @notifier: notifier block managed by caller.
	376	+ *
	377	+ * Will register the notifier into a notification chain that gets called
	378	+ * upon changes to the target value for any device.
	379	+ */
	380	+int dev_pm_qos_add_global_notifier(struct notifier_block *notifier)
	381	+{
	382	+ return blocking_notifier_chain_register(&dev_pm_notifiers, notifier);
	383	+}
	384	+EXPORT_SYMBOL_GPL(dev_pm_qos_add_global_notifier);
	385	+
	386	+/**
	387	+ * dev_pm_qos_remove_global_notifier - deletes notification for changes to
	388	+ * target value of PM QoS constraints for any device
	389	+ *
	390	+ * @notifier: notifier block to be removed.
	391	+ *
	392	+ * Will remove the notifier from the notification chain that gets called
	393	+ * upon changes to the target value for any device.
	394	+ */
	395	+int dev_pm_qos_remove_global_notifier(struct notifier_block *notifier)
	396	+{
	397	+ return blocking_notifier_chain_unregister(&dev_pm_notifiers, notifier);
	398	+}
	399	+EXPORT_SYMBOL_GPL(dev_pm_qos_remove_global_notifier);
...	...	@@ -75,6 +75,7 @@
75	75	int pm_qos_add_notifier(int pm_qos_class, struct notifier_block *notifier);
76	76	int pm_qos_remove_notifier(int pm_qos_class, struct notifier_block *notifier);
77	77	int pm_qos_request_active(struct pm_qos_request *req);
	78	+s32 pm_qos_read_value(struct pm_qos_constraints *c);
78	79
79	80	int dev_pm_qos_add_request(struct device dev, struct dev_pm_qos_request req,
80	81	s32 value);
...	...	@@ -84,6 +85,8 @@
84	85	struct notifier_block *notifier);
85	86	int dev_pm_qos_remove_notifier(struct device *dev,
86	87	struct notifier_block *notifier);
	88	+int dev_pm_qos_add_global_notifier(struct notifier_block *notifier);
	89	+int dev_pm_qos_remove_global_notifier(struct notifier_block *notifier);
87	90	void dev_pm_qos_constraints_init(struct device *dev);
88	91	void dev_pm_qos_constraints_destroy(struct device *dev);
89	92	#else
...	...	@@ -111,6 +114,8 @@
111	114	{ return 0; }
112	115	static inline int pm_qos_request_active(struct pm_qos_request *req)
113	116	{ return 0; }
	117	+static inline s32 pm_qos_read_value(struct pm_qos_constraints *c)
	118	+ { return 0; }
114	119
115	120	static inline int dev_pm_qos_add_request(struct device *dev,
116	121	struct dev_pm_qos_request *req,
...	...	@@ -126,6 +131,12 @@
126	131	{ return 0; }
127	132	static inline int dev_pm_qos_remove_notifier(struct device *dev,
128	133	struct notifier_block *notifier)
	134	+ { return 0; }
	135	+static inline int dev_pm_qos_add_global_notifier(
	136	+ struct notifier_block *notifier)
	137	+ { return 0; }
	138	+static inline int dev_pm_qos_remove_global_notifier(
	139	+ struct notifier_block *notifier)
129	140	{ return 0; }
130	141	static inline void dev_pm_qos_constraints_init(struct device *dev)
131	142	{ return; }
...	...	@@ -140,7 +140,7 @@
140	140	}
141	141	}
142	142
143		-static inline s32 pm_qos_read_value(struct pm_qos_constraints *c)
	143	+s32 pm_qos_read_value(struct pm_qos_constraints *c)
144	144	{
145	145	return c->target_value;
146	146	}