backlight: lp855x: add a device tree structure

Enable supporting the DT structure of LP855x family devices.  If the
platform data is NULL, the driver tries to parse a DT structure.  Then,
the platform data is copied from the DT.  Documentation is added as well.

Signed-off-by: Milo(Woogyom) Kim <milo.kim@ti.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 41 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/video/backlight/lp855x.txt b/Documentation/devicetree/bindings/video/backlight/lp855x.txt
new file mode 100644
index 000000000000..1482103d288f
--- /dev/null
+++ b/Documentation/devicetree/bindings/video/backlight/lp855x.txt
@@ -0,0 +1,41 @@
+lp855x bindings
+
+Required properties:
+  - compatible: "ti,lp8550", "ti,lp8551", "ti,lp8552", "ti,lp8553",
+                "ti,lp8556", "ti,lp8557"
+  - reg: I2C slave address (u8)
+  - dev-ctrl: Value of DEVICE CONTROL register (u8). It depends on the device.
+
+Optional properties:
+  - bl-name: Backlight device name (string)
+  - init-brt: Initial value of backlight brightness (u8)
+  - pwm-period: PWM period value. Set only PWM input mode used (u32)
+  - rom-addr: Register address of ROM area to be updated (u8)
+  - rom-val: Register value to be updated (u8)
+
+Example:
+
+	/* LP8556 */
+	backlight@2c {
+		compatible = "ti,lp8556";
+		reg = <0x2c>;
+
+		bl-name = "lcd-bl";
+		dev-ctrl = /bits/ 8 <0x85>;
+		init-brt = /bits/ 8 <0x10>;
+	};
+
+	/* LP8557 */
+	backlight@2c {
+		compatible = "ti,lp8557";
+		reg = <0x2c>;
+
+		dev-ctrl = /bits/ 8 <0x41>;
+		init-brt = /bits/ 8 <0x0a>;
+
+		/* 4V OV, 4 output LED string enabled */
+		rom_14h {
+			rom-addr = /bits/ 8 <0x14>;
+			rom-val = /bits/ 8 <0xcf>;
+		};
+	};