[PATCH 2/7] PM / QoS: Introduce request and constraint data types for PM QoS flags

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

Introduce struct pm_qos_flags_request and struct pm_qos_flags
representing PM QoS flags request type and PM QoS flags constraint
type, respectively.  With these definitions the data structures
will be arranged so that the list member of a struct pm_qos_flags
object will contain the head of a list of struct pm_qos_flags_request
objects representing all of the "flags" requests present for the
given device.  Then, the effective_flags member of a struct
pm_qos_flags object will contain the bitwise OR of the flags members
of all the struct pm_qos_flags_request objects in the list.

Additionally, introduce helper function pm_qos_update_flags()
allowing the caller to manage the list of struct pm_qos_flags_request
pointed to by the list member of struct pm_qos_flags.

The flags are of type s32 so that the request's "value" field
is always of the same type regardless of what kind of request it
is (latency requests already have value fields of type s32).

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Reviewed-by: Jean Pihet <j-pihet@xxxxxx>
---
 include/linux/pm_qos.h |   17 +++++++++++--
 kernel/power/qos.c     |   63 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 78 insertions(+), 2 deletions(-)

Index: linux/include/linux/pm_qos.h
===================================================================
--- linux.orig/include/linux/pm_qos.h
+++ linux/include/linux/pm_qos.h
@@ -33,6 +33,11 @@ struct pm_qos_request {
 	struct delayed_work work; /* for pm_qos_update_request_timeout */
 };
 
+struct pm_qos_flags_request {
+	struct list_head node;
+	s32 flags;	/* Do not change to 64 bit */
+};
+
 struct dev_pm_qos_request {
 	struct plist_node node;
 	struct device *dev;
@@ -45,8 +50,8 @@ enum pm_qos_type {
 };
 
 /*
- * Note: The lockless read path depends on the CPU accessing
- * target_value atomically.  Atomic access is only guaranteed on all CPU
+ * Note: The lockless read path depends on the CPU accessing target_value
+ * or effective_flags atomically.  Atomic access is only guaranteed on all CPU
  * types linux supports for 32 bit quantites
  */
 struct pm_qos_constraints {
@@ -57,6 +62,11 @@ struct pm_qos_constraints {
 	struct blocking_notifier_head *notifiers;
 };
 
+struct pm_qos_flags {
+	struct list_head list;
+	s32 effective_flags;	/* Do not change to 64 bit */
+};
+
 struct dev_pm_qos {
 	struct pm_qos_constraints latency;
 };
@@ -75,6 +85,9 @@ static inline int dev_pm_qos_request_act
 
 int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
 			 enum pm_qos_req_action action, int value);
+bool pm_qos_update_flags(struct pm_qos_flags *pqf,
+			 struct pm_qos_flags_request *req,
+			 enum pm_qos_req_action action, s32 val);
 void pm_qos_add_request(struct pm_qos_request *req, int pm_qos_class,
 			s32 value);
 void pm_qos_update_request(struct pm_qos_request *req,
Index: linux/kernel/power/qos.c
===================================================================
--- linux.orig/kernel/power/qos.c
+++ linux/kernel/power/qos.c
@@ -213,6 +213,69 @@ int pm_qos_update_target(struct pm_qos_c
 }
 
 /**
+ * pm_qos_flags_remove_req - Remove device PM QoS flags request.
+ * @pqf: Device PM QoS flags set to remove the request from.
+ * @req: Request to remove from the set.
+ */
+static void pm_qos_flags_remove_req(struct pm_qos_flags *pqf,
+				    struct pm_qos_flags_request *req)
+{
+	s32 val = 0;
+
+	list_del(&req->node);
+	list_for_each_entry(req, &pqf->list, node)
+		val |= req->flags;
+
+	pqf->effective_flags = val;
+}
+
+/**
+ * pm_qos_update_flags - Update a set of PM QoS flags.
+ * @pqf: Set of flags to update.
+ * @req: Request to add to the set, to modify, or to remove from the set.
+ * @action: Action to take on the set.
+ * @val: Value of the request to add or modify.
+ *
+ * Update the given set of PM QoS flags and call notifiers if the aggregate
+ * value has changed.  Returns 1 if the aggregate constraint value has changed,
+ * 0 otherwise.
+ */
+bool pm_qos_update_flags(struct pm_qos_flags *pqf,
+			 struct pm_qos_flags_request *req,
+			 enum pm_qos_req_action action, s32 val)
+{
+	unsigned long irqflags;
+	s32 prev_value, curr_value;
+
+	spin_lock_irqsave(&pm_qos_lock, irqflags);
+
+	prev_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
+
+	switch (action) {
+	case PM_QOS_REMOVE_REQ:
+		pm_qos_flags_remove_req(pqf, req);
+		break;
+	case PM_QOS_UPDATE_REQ:
+		pm_qos_flags_remove_req(pqf, req);
+	case PM_QOS_ADD_REQ:
+		req->flags = val;
+		INIT_LIST_HEAD(&req->node);
+		list_add_tail(&req->node, &pqf->list);
+		pqf->effective_flags |= val;
+		break;
+	default:
+		/* no action */
+		;
+	}
+
+	curr_value = list_empty(&pqf->list) ? 0 : pqf->effective_flags;
+
+	spin_unlock_irqrestore(&pm_qos_lock, irqflags);
+
+	return prev_value != curr_value;
+}
+
+/**
  * pm_qos_request - returns current system wide qos expectation
  * @pm_qos_class: identification of which qos value is requested
  *

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