PM QoS: Generalize and export constraints management code

In preparation for the per-device constratins support:
 - rename update_target to pm_qos_update_target
 - generalize and export pm_qos_update_target for usage by the upcoming
   per-device latency constraints framework:
   * operate on struct pm_qos_constraints for constraints management,
   * introduce an 'action' parameter for constraints add/update/remove,
   * the return value indicates if the aggregated constraint value has
     changed,
 - update the internal code to operate on struct pm_qos_constraints
 - add a NULL pointer check in the API functions

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>

1 files changed, 67 insertions, 56 deletions

diff --git a/kernel/power/qos.c b/kernel/power/qos.c
index 4a35fe50b777..7c7cd181cabe 100644
--- a/kernel/power/qos.c
+++ b/kernel/power/qos.c
@@ -122,17 +122,17 @@ static const struct file_operations pm_qos_power_fops = {
 };
 
 /* unlocked internal variant */
-static inline int pm_qos_get_value(struct pm_qos_object *o)
+static inline int pm_qos_get_value(struct pm_qos_constraints *c)
 {
-        if (plist_head_empty(&o->constraints->list))
-                return o->constraints->default_value;
+        if (plist_head_empty(&c->list))
+                return c->default_value;
 
-        switch (o->constraints->type) {
+        switch (c->type) {
         case PM_QOS_MIN:
-                return plist_first(&o->constraints->list)->prio;
+                return plist_first(&c->list)->prio;
 
         case PM_QOS_MAX:
-                return plist_last(&o->constraints->list)->prio;
+                return plist_last(&c->list)->prio;
 
         default:
                 /* runtime check for not using enum */
@@ -140,47 +140,73 @@ static inline int pm_qos_get_value(struct pm_qos_object *o)
         }
 }
 
-static inline s32 pm_qos_read_value(struct pm_qos_object *o)
+static inline s32 pm_qos_read_value(struct pm_qos_constraints *c)
 {
-        return o->constraints->target_value;
+        return c->target_value;
 }
 
-static inline void pm_qos_set_value(struct pm_qos_object *o, s32 value)
+static inline void pm_qos_set_value(struct pm_qos_constraints *c, s32 value)
 {
-        o->constraints->target_value = value;
+        c->target_value = value;
 }
 
-static void update_target(struct pm_qos_object *o, struct plist_node *node,
-                          int del, int value)
+/**
+ * pm_qos_update_target - manages the constraints list and calls the notifiers
+ *  if needed
+ * @c: constraints data struct
+ * @node: request to add to the list, to update or to remove
+ * @action: action to take on the constraints list
+ * @value: value of the request to add or update
+ *
+ * This function returns 1 if the aggregated constraint value has changed, 0
+ *  otherwise.
+ */
+int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
+                         enum pm_qos_req_action action, int value)
 {
         unsigned long flags;
-        int prev_value, curr_value;
+        int prev_value, curr_value, new_value;
 
         spin_lock_irqsave(&pm_qos_lock, flags);
-        prev_value = pm_qos_get_value(o);
-        /* PM_QOS_DEFAULT_VALUE is a signal that the value is unchanged */
-        if (value != PM_QOS_DEFAULT_VALUE) {
+        prev_value = pm_qos_get_value(c);
+        if (value == PM_QOS_DEFAULT_VALUE)
+                new_value = c->default_value;
+        else
+                new_value = value;
+
+        switch (action) {
+        case PM_QOS_REMOVE_REQ:
+                plist_del(node, &c->list);
+                break;
+        case PM_QOS_UPDATE_REQ:
                 /*
                  * to change the list, we atomically remove, reinit
                  * with new value and add, then see if the extremal
                  * changed
                  */
-                plist_del(node, &o->constraints->list);
-                plist_node_init(node, value);
-                plist_add(node, &o->constraints->list);
-        } else if (del) {
-                plist_del(node, &o->constraints->list);
-        } else {
-                plist_add(node, &o->constraints->list);
+                plist_del(node, &c->list);
+        case PM_QOS_ADD_REQ:
+                plist_node_init(node, new_value);
+                plist_add(node, &c->list);
+                break;
+        default:
+                /* no action */
+                ;
         }
-        curr_value = pm_qos_get_value(o);
-        pm_qos_set_value(o, curr_value);
+
+        curr_value = pm_qos_get_value(c);
+        pm_qos_set_value(c, curr_value);
+
         spin_unlock_irqrestore(&pm_qos_lock, flags);
 
-        if (prev_value != curr_value)
-                blocking_notifier_call_chain(o->constraints->notifiers,
+        if (prev_value != curr_value) {
+                blocking_notifier_call_chain(c->notifiers,
                                              (unsigned long)curr_value,
                                              NULL);
+                return 1;
+        } else {
+                return 0;
+        }
 }
 
 /**
@@ -191,7 +217,7 @@ static void update_target(struct pm_qos_object *o, struct plist_node *node,
  */
 int pm_qos_request(int pm_qos_class)
 {
-        return pm_qos_read_value(pm_qos_array[pm_qos_class]);
+        return pm_qos_read_value(pm_qos_array[pm_qos_class]->constraints);
 }
 EXPORT_SYMBOL_GPL(pm_qos_request);
 
@@ -217,20 +243,16 @@ EXPORT_SYMBOL_GPL(pm_qos_request_active);
 void pm_qos_add_request(struct pm_qos_request *req,
                         int pm_qos_class, s32 value)
 {
-        struct pm_qos_object *o =  pm_qos_array[pm_qos_class];
-        int new_value;
+        if (!req) /*guard against callers passing in null */
+                return;
 
         if (pm_qos_request_active(req)) {
                 WARN(1, KERN_ERR "pm_qos_add_request() called for already added request\n");
                 return;
         }
-        if (value == PM_QOS_DEFAULT_VALUE)
-                new_value = o->constraints->default_value;
-        else
-                new_value = value;
-        plist_node_init(&req->node, new_value);
         req->pm_qos_class = pm_qos_class;
-        update_target(o, &req->node, 0, PM_QOS_DEFAULT_VALUE);
+        pm_qos_update_target(pm_qos_array[pm_qos_class]->constraints,
+                             &req->node, PM_QOS_ADD_REQ, value);
 }
 EXPORT_SYMBOL_GPL(pm_qos_add_request);
 
@@ -247,9 +269,6 @@ EXPORT_SYMBOL_GPL(pm_qos_add_request);
 void pm_qos_update_request(struct pm_qos_request *req,
                            s32 new_value)
 {
-        s32 temp;
-        struct pm_qos_object *o;
-
         if (!req) /*guard against callers passing in null */
                 return;
 
@@ -258,15 +277,10 @@ void pm_qos_update_request(struct pm_qos_request *req,
                 return;
         }
 
-        o = pm_qos_array[req->pm_qos_class];
-
-        if (new_value == PM_QOS_DEFAULT_VALUE)
-                temp = o->constraints->default_value;
-        else
-                temp = new_value;
-
-        if (temp != req->node.prio)
-                update_target(o, &req->node, 0, temp);
+        if (new_value != req->node.prio)
+                pm_qos_update_target(
+                        pm_qos_array[req->pm_qos_class]->constraints,
+                        &req->node, PM_QOS_UPDATE_REQ, new_value);
 }
 EXPORT_SYMBOL_GPL(pm_qos_update_request);
 
@@ -280,9 +294,7 @@ EXPORT_SYMBOL_GPL(pm_qos_update_request);
  */
 void pm_qos_remove_request(struct pm_qos_request *req)
 {
-        struct pm_qos_object *o;
-
-        if (req == NULL)
+        if (!req) /*guard against callers passing in null */
                 return;
                 /* silent return to keep pcm code cleaner */
 
@@ -291,8 +303,9 @@ void pm_qos_remove_request(struct pm_qos_request *req)
                 return;
         }
 
-        o = pm_qos_array[req->pm_qos_class];
-        update_target(o, &req->node, 1, PM_QOS_DEFAULT_VALUE);
+        pm_qos_update_target(pm_qos_array[req->pm_qos_class]->constraints,
+                             &req->node, PM_QOS_REMOVE_REQ,
+                             PM_QOS_DEFAULT_VALUE);
         memset(req, 0, sizeof(*req));
 }
 EXPORT_SYMBOL_GPL(pm_qos_remove_request);
@@ -396,7 +409,6 @@ static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
 {
         s32 value;
         unsigned long flags;
-        struct pm_qos_object *o;
         struct pm_qos_request *req = filp->private_data;
 
         if (!req)
@@ -404,9 +416,8 @@ static ssize_t pm_qos_power_read(struct file *filp, char __user *buf,
         if (!pm_qos_request_active(req))
                 return -EINVAL;
 
-        o = pm_qos_array[req->pm_qos_class];
         spin_lock_irqsave(&pm_qos_lock, flags);
-        value = pm_qos_get_value(o);
+        value = pm_qos_get_value(pm_qos_array[req->pm_qos_class]->constraints);
         spin_unlock_irqrestore(&pm_qos_lock, flags);
 
         return simple_read_from_buffer(buf, count, f_pos, &value, sizeof(s32));