[PATCH v8 3/3] drm/tinydrm: Add devres versions of backlight_get

[Meghana Madhyastha]

Add devm_backlight_get and the corresponding release
function because some drivers use devres versions of functions
for requiring device resources.

Signed-off-by: Meghana Madhyastha <meghana.madhyastha at gmail.com>
---
Changes in v8:
-Put the devres version to backlight.c along with backlight_get.

 drivers/gpu/drm/tinydrm/mi0283qt.c  |  2 +-
 drivers/video/backlight/backlight.c | 31 +++++++++++++++++++++++++++++++
 include/linux/backlight.h           | 16 ++++++++++++++++
 3 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/tinydrm/mi0283qt.c b/drivers/gpu/drm/tinydrm/mi0283qt.c
index edf9502..03fec36 100644
--- a/drivers/gpu/drm/tinydrm/mi0283qt.c
+++ b/drivers/gpu/drm/tinydrm/mi0283qt.c
@@ -190,7 +190,7 @@ static int mi0283qt_probe(struct spi_device *spi)
 	if (IS_ERR(mipi->regulator))
 		return PTR_ERR(mipi->regulator);
 
-	mipi->backlight = backlight_get(dev);
+	mipi->backlight = devm_backlight_get(dev);
 	if (IS_ERR(mipi->backlight))
 		return PTR_ERR(mipi->backlight);
 
diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index 1debb60..9b24dc2 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -618,6 +618,37 @@ struct backlight_device *backlight_get(struct device *dev)
 	return bd;
 }
 EXPORT_SYMBOL(backlight_get);
+
+static void devm_backlight_get_release(void *data)
+{
+	backlight_put(data);
+}
+
+/**
+ * devm_backlight_get - Resource-managed backlight_get()
+ * @dev: Device
+ *
+ * Device managed version of backlight_get(). The reference on the backlight
+ * device is automatically dropped on driver detach.
+ */
+struct backlight_device *devm_backlight_get(struct device *dev)
+{
+	struct backlight_device *bd;
+	int ret;
+
+	bd = backlight_get(dev);
+	if (!bd)
+		return NULL;
+
+	ret = devm_add_action(dev, devm_backlight_get_release, bd);
+	if (ret) {
+		backlight_put(bd);
+		return ERR_PTR(ret);
+	}
+
+	return bd;
+}
+EXPORT_SYMBOL(devm_backlight_get);
 #endif
 
 static void __exit backlight_class_exit(void)
diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index 1d713b3..0bfadb6 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -183,6 +183,16 @@ static inline int backlight_disable(struct backlight_device *bd)
 	return backlight_update_status(bd);
 }
 
+/**
+ ** backlight_put - Drop backlight reference
+ ** @bd: the backlight device to put
+ **/
+static inline void backlight_put(struct backlight_device *bd)
+{
+	if (bd)
+		put_device(&bd->dev);
+}
+
 struct generic_bl_info {
 	const char *name;
 	int max_intensity;
@@ -204,11 +214,17 @@ of_find_backlight_by_node(struct device_node *node)
 
 #if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
 struct backlight_device *backlight_get(struct device *dev);
+struct backlight_device *devm_backlight_get(struct device *dev);
 #else
 static inline struct backlight_device *backlight_get(struct device *dev)
 {
 	return NULL;
 }
+
+static inline struct backlight_device *devm_backlight_get(struct device *dev)
+{
+	return NULL;
+}
 #endif
 
 #endif
-- 
2.7.4