[PATCH 5/7] PM QoS: generalize and export the constraints management code

jean.pihet
2011-08-17T19:40:35Z

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>
---
include/linux/pm_qos.h | 14 ++++++
kernel/power/qos.c | 123 ++++++++++++++++++++++++++----------------------
2 files changed, 81 insertions(+), 56 deletions(-)

diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h
index 9772311..84aa150 100644
--- a/include/linux/pm_qos.h
+++ b/include/linux/pm_qos.h
@@ -44,7 +44,16 @@ struct pm_qos_constraints {
struct blocking_notifier_head *notifiers;
};

+/* Action requested to pm_qos_update_target */
+enum pm_qos_req_action {
+ PM_QOS_ADD_REQ, /* Add a new request */
+ PM_QOS_UPDATE_REQ, /* Update an existing request */
+ PM_QOS_REMOVE_REQ /* Remove an existing request */
+};
+
#ifdef CONFIG_PM
+int pm_qos_update_target(struct pm_qos_constraints *c, struct plist_node *node,
+ enum pm_qos_req_action action, int value);
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,
@@ -56,6 +65,11 @@ 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);
#else
+static inline int pm_qos_update_target(struct pm_qos_constraints *c,
+ struct plist_node *node,
+ enum pm_qos_req_action action,
+ int value)
+ { return 0; }
static inline void pm_qos_add_request(struct pm_qos_request *req,
int pm_qos_class, s32 value)
{ return; }
diff --git a/kernel/power/qos.c b/kernel/power/qos.c
index 4a35fe5..7c7cd18 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));
--
1.7.4.1