[media] media: ov2640: dt: add the device tree binding document

Add the document for ov2640 dt.

Cc: devicetree@vger.kernel.org
Signed-off-by: Josh Wu <josh.wu@atmel.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

Documentation/devicetree/bindings/media/i2c/ov2640.txt

+* Omnivision OV2640 CMOS sensor
+
+The Omnivision OV2640 sensor support multiple resolutions output, such as
+CIF, SVGA, UXGA. It also can support YUV422/420, RGB565/555 or raw RGB
+output format.
+
+Required Properties:
+- compatible: should be "ovti,ov2640"
+- clocks: reference to the xvclk input clock.
+- clock-names: should be "xvclk".
+
+Optional Properties:
+- resetb-gpios: reference to the GPIO connected to the resetb pin, if any.
+- pwdn-gpios: reference to the GPIO connected to the pwdn pin, if any.
+
+The device node must contain one 'port' child node for its digital output
+video port, in accordance with the video interface bindings defined in
+Documentation/devicetree/bindings/media/video-interfaces.txt.
+
+Example:
+
+	i2c1: i2c@f0018000 {
+		ov2640: camera@0x30 {
+			compatible = "ovti,ov2640";
+			reg = <0x30>;
+
+			pinctrl-names = "default";
+			pinctrl-0 = <&pinctrl_pck1 &pinctrl_ov2640_pwdn &pinctrl_ov2640_resetb>;
+
+			resetb-gpios = <&pioE 24 GPIO_ACTIVE_LOW>;
+			pwdn-gpios = <&pioE 29 GPIO_ACTIVE_HIGH>;
+
+			clocks = <&pck1>;
+			clock-names = "xvclk";
+
+			assigned-clocks = <&pck1>;
+			assigned-clock-rates = <25000000>;
+
+			port {
+				ov2640_0: endpoint {
+					remote-endpoint = <&isi_0>;
+					bus-width = <8>;
+				};
+			};
+		};
+	};