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>

2 files changed, 12 insertions, 10 deletions

diff --git a/include/linux/pm.h b/include/linux/pm.h
index d78187e9ca99..62a876ec4d4e 100644
--- a/include/linux/pm.h
+++ b/include/linux/pm.h
@@ -326,6 +326,7 @@ extern struct dev_pm_ops generic_subsys_pm_ops;
  *			requested by a driver.
  */
 
+#define PM_EVENT_INVALID	(-1)
 #define PM_EVENT_ON		0x0000
 #define PM_EVENT_FREEZE 	0x0001
 #define PM_EVENT_SUSPEND	0x0002
@@ -346,6 +347,7 @@ extern struct dev_pm_ops generic_subsys_pm_ops;
 #define PM_EVENT_AUTO_SUSPEND	(PM_EVENT_AUTO | PM_EVENT_SUSPEND)
 #define PM_EVENT_AUTO_RESUME	(PM_EVENT_AUTO | PM_EVENT_RESUME)
 
+#define PMSG_INVALID	((struct pm_message){ .event = PM_EVENT_INVALID, })
 #define PMSG_ON		((struct pm_message){ .event = PM_EVENT_ON, })
 #define PMSG_FREEZE	((struct pm_message){ .event = PM_EVENT_FREEZE, })
 #define PMSG_QUIESCE	((struct pm_message){ .event = PM_EVENT_QUIESCE, })
@@ -419,13 +421,6 @@ enum rpm_request {
 	RPM_REQ_RESUME,
 };
 
-/* Per-device PM QoS constraints data struct state */
-enum dev_pm_qos_state {
-	DEV_PM_QOS_NO_DEVICE,		/* No device present */
-	DEV_PM_QOS_DEVICE_PRESENT,	/* Device present, data not allocated */
-	DEV_PM_QOS_ALLOCATED,		/* Device present, data allocated */
-};
-
 struct wakeup_source;
 
 struct pm_domain_data {
@@ -488,7 +483,6 @@ struct dev_pm_info {
 #endif
 	struct pm_subsys_data	*subsys_data;  /* Owned by the subsystem. */
 	struct pm_qos_constraints *constraints;
-	enum dev_pm_qos_state	constraints_state;
 };
 
 extern void update_pm_runtime_accounting(struct device *dev);
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