This contains the backlight portion of Meghana Madhyastha's patch set to

migrate the backlight helpers from tinydrm to the backlight subsystem.
 
 https://patchwork.freedesktop.org/series/36522/
 
 Cc: Meghana Madhyastha <meghana.madhyastha@gmail.com>
 -----BEGIN PGP SIGNATURE-----
 
 iQEzBAABCAAdFiEEfxcpfMSgdnQMs+QqlvcN/ahKBwoFAlpvdTQACgkQlvcN/ahK
 Bwp5Pgf8Cfn7p7/HV5npF0b0NZ3w0FLF+AjggxKdKBNsVYdO1qGrhfQJviuMRj7c
 cqm+SQ4OFJEwGMqVGsZLgRkyVrbCma/OZEcipJiSGHLG9owDgVFYTQ4bnakmdt1m
 QYJTETNxoNJ1EHCG1tfr9/jDR3GPL3OnSUOWnlTXDzpJ2PCw4BB0uArqG+pgmyhJ
 DCMdvYkQ+5tYB814otnN3zklklQITNGww8LTJMtDFyJVIz2RZHioq5JqXD48UfMb
 haDVbiYsOamw+eP4z5uyfCi1rKwzpPhas9IpeDn5gY6rEp/t+GTkSr0JHUEs/iB+
 +eAH076eTp3M8iv7YF67XYLZQeDuwQ==
 =azAl
 -----END PGP SIGNATURE-----

Merge tag 'topic/backlight_for_lag-2018-01-29' of git://anongit.freedesktop.org/drm/drm-misc into drm-misc-next

This contains the backlight portion of Meghana Madhyastha's patch set to
migrate the backlight helpers from tinydrm to the backlight subsystem.

https://patchwork.freedesktop.org/series/36522/

Cc: Meghana Madhyastha <meghana.madhyastha@gmail.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>

# gpg: Signature made Mon 29 Jan 2018 02:25:40 PM EST
# gpg:                using RSA key 7F17297CC4A076740CB3E42A96F70DFDA84A070A
# gpg: Good signature from "Sean Paul <seanpaul@chromium.org>" [unknown]
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg:          There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 1C5E AB9E D7C9 DDE9 E7F2  087C 732C 0025 72DC AF79
#      Subkey fingerprint: 7F17 297C C4A0 7674 0CB3  E42A 96F7 0DFD A84A 070A
Link: https://patchwork.freedesktop.org/patch/msgid/20180129192950.bvmhkz3h42t5a25r@art_vandelay

drivers/video/backlight/backlight.c

@@ -580,6 +580,79 @@ struct backlight_device *of_find_backlight_by_node(struct device_node *node)
 EXPORT_SYMBOL(of_find_backlight_by_node);
 #endif
 
+/**
+ * of_find_backlight - Get backlight device
+ * @dev: Device
+ *
+ * This function looks for a property named 'backlight' on the DT node
+ * connected to @dev and looks up the backlight device.
+ *
+ * Call backlight_put() to drop the reference on the backlight device.
+ *
+ * Returns:
+ * A pointer to the backlight device if found.
+ * Error pointer -EPROBE_DEFER if the DT property is set, but no backlight
+ * device is found.
+ * NULL if there's no backlight property.
+ */
+struct backlight_device *of_find_backlight(struct device *dev)
+{
+	struct backlight_device *bd = NULL;
+	struct device_node *np;
+
+	if (!dev)
+		return NULL;
+
+	if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
+		np = of_parse_phandle(dev->of_node, "backlight", 0);
+		if (np) {
+			bd = of_find_backlight_by_node(np);
+			of_node_put(np);
+			if (!bd)
+				return ERR_PTR(-EPROBE_DEFER);
+			/*
+			 * Note: gpio_backlight uses brightness as
+			 * power state during probe
+			 */
+			if (!bd->props.brightness)
+				bd->props.brightness = bd->props.max_brightness;
+		}
+	}
+
+	return bd;
+}
+EXPORT_SYMBOL(of_find_backlight);
+
+static void devm_backlight_release(void *data)
+{
+	backlight_put(data);
+}
+
+/**
+ * devm_of_find_backlight - Resource-managed of_find_backlight()
+ * @dev: Device
+ *
+ * Device managed version of of_find_backlight().
+ * The reference on the backlight device is automatically
+ * dropped on driver detach.
+ */
+struct backlight_device *devm_of_find_backlight(struct device *dev)
+{
+	struct backlight_device *bd;
+	int ret;
+
+	bd = of_find_backlight(dev);
+	if (IS_ERR_OR_NULL(bd))
+		return bd;
+	ret = devm_add_action(dev, devm_backlight_release, bd);
+	if (ret) {
+		backlight_put(bd);
+		return ERR_PTR(ret);
+	}
+	return bd;
+}
+EXPORT_SYMBOL(devm_of_find_backlight);
+
 static void __exit backlight_class_exit(void)
 {
 	class_destroy(backlight_class);

include/linux/backlight.h

@@ -130,6 +130,48 @@ static inline int backlight_update_status(struct backlight_device *bd)
 	return ret;
 }
 
+/**
+ * backlight_enable - Enable backlight
+ * @bd: the backlight device to enable
+ */
+static inline int backlight_enable(struct backlight_device *bd)
+{
+	if (!bd)
+		return 0;
+
+	bd->props.power = FB_BLANK_UNBLANK;
+	bd->props.fb_blank = FB_BLANK_UNBLANK;
+	bd->props.state &= ~BL_CORE_FBBLANK;
+
+	return backlight_update_status(bd);
+}
+
+/**
+ * backlight_disable - Disable backlight
+ * @bd: the backlight device to disable
+ */
+static inline int backlight_disable(struct backlight_device *bd)
+{
+	if (!bd)
+		return 0;
+
+	bd->props.power = FB_BLANK_POWERDOWN;
+	bd->props.fb_blank = FB_BLANK_POWERDOWN;
+	bd->props.state |= BL_CORE_FBBLANK;
+
+	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);
+}
+
 extern struct backlight_device *backlight_device_register(const char *name,
 	struct device *dev, void *devdata, const struct backlight_ops *ops,
 	const struct backlight_properties *props);
@@ -173,4 +215,20 @@ of_find_backlight_by_node(struct device_node *node)
 }
 #endif
 
+#if IS_ENABLED(CONFIG_BACKLIGHT_CLASS_DEVICE)
+struct backlight_device *of_find_backlight(struct device *dev);
+struct backlight_device *devm_of_find_backlight(struct device *dev);
+#else
+static inline struct backlight_device *of_find_backlight(struct device *dev)
+{
+	return NULL;
+}
+
+static inline struct backlight_device *
+devm_of_find_backlight(struct device *dev)
+{
+	return NULL;
+}
+#endif
+
 #endif