[PATCH v7 3/3] 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 use devres versions of functions
for requiring device resources.

Signed-off-by: Meghana Madhyastha <meghana.madhyastha at gmail.com>
---
Changes in v7:
-None

 drivers/gpu/drm/drm_of.c           | 40 ++++++++++++++++++++++++++++++++++++++
 drivers/gpu/drm/tinydrm/mi0283qt.c |  2 +-
 include/drm/drm_of.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 7417725..82b5113 100644
--- a/drivers/gpu/drm/drm_of.c
+++ b/drivers/gpu/drm/drm_of.c
@@ -305,3 +305,43 @@ 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 5e3d635..d37f658 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 = 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/drm/drm_of.h b/include/drm/drm_of.h
index 6e93311..b95f3fb 100644
--- a/include/drm/drm_of.h
+++ b/include/drm/drm_of.h
@@ -30,6 +30,7 @@ int drm_of_find_panel_or_bridge(const struct device_node *np,
 				struct drm_panel **panel,
 				struct drm_bridge **bridge);
 struct backlight_device *drm_of_find_backlight(struct device *dev);
+struct backlight_device *devm_drm_of_find_backlight(struct device *dev);
 #else
 static inline uint32_t drm_of_find_possible_crtcs(struct drm_device *dev,
 						  struct device_node *port)
@@ -72,6 +73,12 @@ 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
 
 static inline int drm_of_encoder_active_endpoint_id(struct device_node *node,
-- 
2.7.4