PM / runtime: Add new helper for conditional usage count incrementation

Introduce a new runtime PM function, pm_runtime_get_if_in_use(),
that will increment the device's runtime PM usage counter and
return 1 if its status is RPM_ACTIVE and its usage counter
is greater than 0 at the same time (0 will be returned otherwise).

This is useful for things that should only be done if the device
is active (from the runtime PM perspective) and used by somebody
(as indicated by the usage counter) already and they are not worth
bothering otherwise.

Requested-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt
index 0784bc3a2ab51bd2d624644d6ea5a41e44529307..7328cf85236c2b2bc5a4c078dc9f81f2e3febd11 100644 (file)
--- a/Documentation/power/runtime_pm.txt
+++ b/Documentation/power/runtime_pm.txt
@@ -371,6 +371,12 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h:
     - increment the device's usage counter, run pm_runtime_resume(dev) and
       return its result
 
+  int pm_runtime_get_if_in_use(struct device *dev);
+    - return -EINVAL if 'power.disable_depth' is nonzero; otherwise, if the
+      runtime PM status is RPM_ACTIVE and the runtime PM usage counter is
+      nonzero, increment the counter and return 1; otherwise return 0 without
+      changing the counter
+
   void pm_runtime_put_noidle(struct device *dev);
     - decrement the device's usage counter
 

diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
index ab3fcd9f6c982f65cffd50bcfa42abb89555c212..4c7055009bd6ac88477458cf3fc551a966d2ad37 100644 (file)
--- a/drivers/base/power/runtime.c
+++ b/drivers/base/power/runtime.c
@@ -965,6 +965,30 @@ int __pm_runtime_resume(struct device *dev, int rpmflags)
 }
 EXPORT_SYMBOL_GPL(__pm_runtime_resume);
 
+/**
+ * pm_runtime_get_if_in_use - Conditionally bump up the device's usage counter.
+ * @dev: Device to handle.
+ *
+ * Return -EINVAL if runtime PM is disabled for the device.
+ *
+ * If that's not the case and if the device's runtime PM status is RPM_ACTIVE
+ * and the runtime PM usage counter is nonzero, increment the counter and
+ * return 1.  Otherwise return 0 without changing the counter.
+ */
+int pm_runtime_get_if_in_use(struct device *dev)
+{
+       unsigned long flags;
+       int retval;
+
+       spin_lock_irqsave(&dev->power.lock, flags);
+       retval = dev->power.disable_depth > 0 ? -EINVAL :
+               dev->power.runtime_status == RPM_ACTIVE
+                       && atomic_inc_not_zero(&dev->power.usage_count);
+       spin_unlock_irqrestore(&dev->power.lock, flags);
+       return retval;
+}
+EXPORT_SYMBOL_GPL(pm_runtime_get_if_in_use);
+
 /**
  * __pm_runtime_set_status - Set runtime PM status of a device.
  * @dev: Device to handle.

diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
index 3bdbb4189780043f4e83af2e7d02401251f181a7..7af093d6a4dd16016ef5699ec2b593dda1902e06 100644 (file)
--- a/include/linux/pm_runtime.h
+++ b/include/linux/pm_runtime.h
@@ -39,6 +39,7 @@ extern int pm_runtime_force_resume(struct device *dev);
 extern int __pm_runtime_idle(struct device *dev, int rpmflags);
 extern int __pm_runtime_suspend(struct device *dev, int rpmflags);
 extern int __pm_runtime_resume(struct device *dev, int rpmflags);
+extern int pm_runtime_get_if_in_use(struct device *dev);
 extern int pm_schedule_suspend(struct device *dev, unsigned int delay);
 extern int __pm_runtime_set_status(struct device *dev, unsigned int status);
 extern int pm_runtime_barrier(struct device *dev);
@@ -143,6 +144,10 @@ static inline int pm_schedule_suspend(struct device *dev, unsigned int delay)
 {
        return -ENOSYS;
 }
+static inline int pm_runtime_get_if_in_use(struct device *dev)
+{
+       return -EINVAL;
+}
 static inline int __pm_runtime_set_status(struct device *dev,
                                            unsigned int status) { return 0; }
 static inline int pm_runtime_barrier(struct device *dev) { return 0; }