PM / QoS: Add function dev_pm_qos_read_value() (v3)

To read the current PM QoS value for a given device we need to
make sure that the device's power.constraints object won't be
removed while we're doing that.  For this reason, put the
operation under dev->power.lock and acquire the lock
around the initialization and removal of power.constraints.

Moreover, since we're using the value of power.constraints to
determine whether or not the object is present, the
power.constraints_state field isn't necessary any more and may be
removed.  However, dev_pm_qos_add_request() needs to check if the
device is being removed from the system before allocating a new
PM QoS constraints object for it, so make it use the
power.power_state field of struct device for this purpose.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

1 files changed, 10 insertions, 2 deletions

diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h
index ca7bd3f98cb4..83b0ea302a80 100644
--- a/include/linux/pm_qos.h
+++ b/include/linux/pm_qos.h
@@ -7,6 +7,7 @@
 #include <linux/plist.h>
 #include <linux/notifier.h>
 #include <linux/miscdevice.h>
+#include <linux/device.h>
 
 #define PM_QOS_RESERVED 0
 #define PM_QOS_CPU_DMA_LATENCY 1
@@ -77,6 +78,7 @@ 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);
 
+s32 dev_pm_qos_read_value(struct device *dev);
 int dev_pm_qos_add_request(struct device *dev, struct dev_pm_qos_request *req,
                            s32 value);
 int dev_pm_qos_update_request(struct dev_pm_qos_request *req, s32 new_value);
@@ -117,6 +119,8 @@ static inline int pm_qos_request_active(struct pm_qos_request *req)
 static inline s32 pm_qos_read_value(struct pm_qos_constraints *c)
                         { return 0; }
 
+static inline s32 dev_pm_qos_read_value(struct device *dev)
+                        { return 0; }
 static inline int dev_pm_qos_add_request(struct device *dev,
                                          struct dev_pm_qos_request *req,
                                          s32 value)
@@ -139,9 +143,13 @@ 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; }
+{
+        dev->power.power_state = PMSG_ON;
+}
 static inline void dev_pm_qos_constraints_destroy(struct device *dev)
-                        { return; }
+{
+        dev->power.power_state = PMSG_INVALID;
+}
 #endif
 
 #endif