[PATCH v6 2/2] drm/tinydrm: Add devres versions of drm_of_find_backlight

[Meghana Madhyastha]

Add devm_drm_of_find_backlight and the corresponding release
function because some drivers such as tinydrm use devres versions
of functions for requiring device resources.

Signed-off-by: Meghana Madhyastha <meghana.madhyastha at gmail.com>
---
Changes in v6:
- Remove docstring for devm_drm_of_backlight_release because it is
 and internal function.

 drivers/gpu/drm/drm_of.c           | 40 ++++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/tinydrm/mi0283qt.c |  2 +-
 include/linux/backlight.h          |  7 +++++++
 3 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_of.c b/drivers/gpu/drm/drm_of.c
index d878d3a..6fb3fe5 100644
--- a/drivers/gpu/drm/drm_of.c
+++ b/drivers/gpu/drm/drm_of.c
@@ -304,3 +304,43 @@ struct backlight_device *drm_of_find_backlight(struct device *dev)
 	return backlight;
 }
 EXPORT_SYMBOL(drm_of_find_backlight);
+
+static void devm_drm_of_find_backlight_release(void *data)
+{
+	put_device(data);
+}
+
+/**
+ * devm_drm_of_find_backlight - Find backlight device in device-tree
+ * devres version of the function
+ * @dev: Device
+ *
+ * This is the devres version of the function drm_of_find_backlight.
+ * Some drivers use devres versions of functions for
+ * requiring device resources.
+ *
+ * Returns:
+ * NULL if there's no backlight property.
+ * Error pointer -EPROBE_DEFER if the DT node is found, but no backlight device
+ * is found.
+ * If the backlight device is found, a pointer to the structure is returned.
+ */
+struct backlight_device *devm_drm_of_find_backlight(struct device *dev)
+{
+	struct backlight_device *backlight;
+	int ret;
+
+	backlight = drm_of_find_backlight(dev);
+	if (IS_ERR_OR_NULL(backlight))
+		return backlight;
+
+	ret = devm_add_action(dev, devm_drm_of_find_backlight_release,
+			      &backlight->dev);
+	if (ret) {
+		put_device(&backlight->dev);
+		return ERR_PTR(ret);
+	}
+
+	return backlight;
+}
+EXPORT_SYMBOL(devm_drm_of_find_backlight);
diff --git a/drivers/gpu/drm/tinydrm/mi0283qt.c b/drivers/gpu/drm/tinydrm/mi0283qt.c
index 682b4db..6724e5e 100644
--- a/drivers/gpu/drm/tinydrm/mi0283qt.c
+++ b/drivers/gpu/drm/tinydrm/mi0283qt.c
@@ -189,7 +189,7 @@ static int mi0283qt_probe(struct spi_device *spi)
 	if (IS_ERR(mipi->regulator))
 		return PTR_ERR(mipi->regulator);
 
-	mipi->backlight = drm_of_find_backlight(dev);
+	mipi->backlight = devm_drm_of_find_backlight(dev);
 	if (IS_ERR(mipi->backlight))
 		return PTR_ERR(mipi->backlight);
 
diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index 47a095e..f601f15 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -175,12 +175,19 @@ of_find_backlight_by_node(struct device_node *node)
 #if defined(CONFIG_OF) && IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
 struct backlight_device *
 drm_of_find_backlight(struct device *dev);
+devm_drm_of_find_backlight(struct device *dev);
 #else
 static inline struct backlight_device *
 drm_of_find_backlight(struct device *dev)
 {
 	return NULL;
 }
+
+static inline struct backlight_device *
+devm_drm_of_find_backlight(struct device *dev)
+{
+	return NULL;
+}
 #endif
 
 #endif
-- 
2.7.4