[PATCH v3 04/13] driver core: Add dev_set_drv_queue_sync_state()

[Ulf Hansson <ulf.hansson@linaro.org>]

Similar to the dev_set_drv_sync_state() helper, let's add another one to
allow subsystem level code to set the ->queue_sync_state() callback for a
driver that has not already set it.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
---

Changes in v3:
	- Added documentation.

---
 include/linux/device.h | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/include/linux/device.h b/include/linux/device.h
index 209feea8050e..e32f85e8d80c 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -1097,6 +1097,26 @@ static inline int dev_set_drv_sync_state(struct device *dev,
 	return 0;
 }
 
+/**
+ * dev_set_drv_sync_state - Assign the ->queue_sync_state callback for a device.
+ * @dev: The device.
+ * @fn: The callback.
+ *
+ * This function dynamically tries to assign the driver's ->queue_sync_state()
+ * callback for the corresponding @dev.
+ */
+static inline int dev_set_drv_queue_sync_state(struct device *dev,
+					       void (*fn)(struct device *dev))
+{
+	if (!dev || !dev->driver)
+		return 0;
+	if (dev->driver->queue_sync_state && dev->driver->queue_sync_state != fn)
+		return -EBUSY;
+	if (!dev->driver->queue_sync_state)
+		dev->driver->queue_sync_state = fn;
+	return 0;
+}
+
 static inline void dev_set_removable(struct device *dev,
 				     enum device_removable removable)
 {
-- 
2.43.0