[media] Documentation: dt: Add binding documentation for S5C73M3 camera

This adds DT binding documentation for Samsung S5C73M3 camera sensor
with an embedded ISP.
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

Documentation/devicetree/bindings/media/samsung-s5c73m3.txt

+Samsung S5C73M3 8Mp camera ISP
+------------------------------
+
+The S5C73M3 camera ISP supports MIPI CSI-2 and parallel (ITU-R BT.656) video
+data busses. The I2C bus is the main control bus and additionally the SPI bus
+is used, mostly for transferring the firmware to and from the device. Two
+slave device nodes corresponding to these control bus interfaces are required
+and should be placed under respective bus controller nodes.
+
+I2C slave device node
+---------------------
+
+Required properties:
+
+- compatible	    : "samsung,s5c73m3";
+- reg		    : I2C slave address of the sensor;
+- vdd-int-supply    : digital power supply (1.2V);
+- vdda-supply	    : analog power supply (1.2V);
+- vdd-reg-supply    : regulator input power supply (2.8V);
+- vddio-host-supply : host I/O power supply (1.8V to 2.8V);
+- vddio-cis-supply  : CIS I/O power supply (1.2V to 1.8V);
+- vdd-af-supply     : lens power supply (2.8V);
+- xshutdown-gpios   : specifier of GPIO connected to the XSHUTDOWN pin;
+- standby-gpios     : specifier of GPIO connected to the STANDBY pin;
+- clocks	    : should contain list of phandle and clock specifier pairs
+		      according to common clock bindings for the clocks described
+		      in the clock-names property;
+- clock-names	    : should contain "cis_extclk" entry for the CIS_EXTCLK clock;
+
+Optional properties:
+
+- clock-frequency   : the frequency at which the "cis_extclk" clock should be
+		      configured to operate, in Hz; if this property is not
+		      specified default 24 MHz value will be used.
+
+The common video interfaces bindings (see video-interfaces.txt) should be used
+to specify link from the S5C73M3 to an external image data receiver. The S5C73M3
+device node should contain one 'port' child node with an 'endpoint' subnode for
+this purpose. The data link from a raw image sensor to the S5C73M3 can be
+similarly specified, but it is optional since the S5C73M3 ISP and a raw image
+sensor are usually inseparable and form a hybrid module.
+
+Following properties are valid for the endpoint node(s):
+
+endpoint subnode
+----------------
+
+- data-lanes : (optional) specifies MIPI CSI-2 data lanes as covered in
+  video-interfaces.txt. This sensor doesn't support data lane remapping
+  and physical lane indexes in subsequent elements of the array should
+  be only consecutive ascending values.
+
+SPI device node
+---------------
+
+Required properties:
+
+- compatible	    : "samsung,s5c73m3";
+
+For more details see description of the SPI busses bindings
+(../spi/spi-bus.txt) and bindings of a specific bus controller.
+
+Example:
+
+i2c@138A000000 {
+	...
+	s5c73m3@3c {
+		compatible = "samsung,s5c73m3";
+		reg = <0x3c>;
+		vdd-int-supply = <&buck9_reg>;
+		vdda-supply = <&ldo17_reg>;
+		vdd-reg-supply = <&cam_io_reg>;
+		vddio-host-supply = <&ldo18_reg>;
+		vddio-cis-supply = <&ldo9_reg>;
+		vdd-af-supply = <&cam_af_reg>;
+		clock-frequency = <24000000>;
+		clocks = <&clk 0>;
+		clock-names = "cis_extclk";
+		reset-gpios = <&gpf1 3 1>;
+		standby-gpios = <&gpm0 1 1>;
+		port {
+			s5c73m3_ep: endpoint {
+				remote-endpoint = <&csis0_ep>;
+				data-lanes = <1 2 3 4>;
+			};
+		};
+	};
+};
+
+spi@1392000 {
+	...
+	s5c73m3_spi: s5c73m3@0 {
+		compatible = "samsung,s5c73m3";
+		reg = <0>;
+		...
+	};
+};