From bc0a5455455a9b595be80092c1afb97d7a110af5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= <noralf@tronnes.org>
Date: Sat, 9 May 2020 16:16:10 +0200
Subject: backlight: Add backlight_device_get_by_name()
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Git-commit: 479da1f538a2f3547e15f9d5922c611b69ec2fbc
Patch-mainline: v5.8-rc1
References: jsc#SLE-12680, jsc#SLE-12880, jsc#SLE-12882, jsc#SLE-12883, jsc#SLE-13496, jsc#SLE-15322

Add a way to lookup a backlight device based on its name.
Will be used by a USB display gadget getting the name from configfs.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Acked-by: Jingoo Han <jingoohan1@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/video/backlight/backlight.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index cac3e35d7630..92d80aa0c0ef 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -432,6 +432,27 @@ struct backlight_device *backlight_device_get_by_type(enum backlight_type type)
 }
 EXPORT_SYMBOL(backlight_device_get_by_type);
 
+/**
+ * backlight_device_get_by_name - Get backlight device by name
+ * @name: Device name
+ *
+ * This function looks up a backlight device by its name. It obtains a reference
+ * on the backlight device and it is the caller's responsibility to drop the
+ * reference by calling backlight_put().
+ *
+ * Returns:
+ * A pointer to the backlight device if found, otherwise NULL.
+ */
+struct backlight_device *backlight_device_get_by_name(const char *name)
+{
+	struct device *dev;
+
+	dev = class_find_device_by_name(backlight_class, name);
+
+	return dev ? to_backlight_device(dev) : NULL;
+}
+EXPORT_SYMBOL(backlight_device_get_by_name);
+
 /**
  * backlight_device_unregister - unregisters a backlight device object.
  * @bd: the backlight device object to be unregistered and freed.
-- 
2.28.0