[media] dt-bindings: media: Add MAX2175 binding description

Add device tree binding documentation for MAX2175 RF to bits tuner
device.
Signed-off-by: Ramesh Shanmugasundaram <ramesh.shanmugasundaram@bp.renesas.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Hans Verkuil <hansverk@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

Documentation/devicetree/bindings/media/i2c/max2175.txt

+Maxim Integrated MAX2175 RF to Bits tuner
+-----------------------------------------
+
+The MAX2175 IC is an advanced analog/digital hybrid-radio receiver with
+RF to Bits® front-end designed for software-defined radio solutions.
+
+Required properties:
+--------------------
+- compatible: "maxim,max2175" for MAX2175 RF-to-bits tuner.
+- clocks: clock specifier.
+- port: child port node corresponding to the I2S output, in accordance with
+	the video interface bindings defined in
+	Documentation/devicetree/bindings/media/video-interfaces.txt. The port
+	node must contain at least one endpoint.
+
+Optional properties:
+--------------------
+- maxim,master	      : phandle to the master tuner if it is a slave. This
+			is used to define two tuners in diversity mode
+			(1 master, 1 slave). By default each tuner is an
+			individual master.
+- maxim,refout-load   : load capacitance value (in picofarads) on reference
+			output drive level. The possible load values are:
+			 0 (default - refout disabled)
+			10
+			20
+			30
+			40
+			60
+			70
+- maxim,am-hiz-filter : empty property indicates the AM Hi-Z filter is used
+			in this hardware for AM antenna input.
+
+Example:
+--------
+
+Board specific DTS file
+
+/* Fixed XTAL clock node */
+maxim_xtal: clock {
+	compatible = "fixed-clock";
+	#clock-cells = <0>;
+	clock-frequency = <36864000>;
+};
+
+/* A tuner device instance under i2c bus */
+max2175_0: tuner@60 {
+	compatible = "maxim,max2175";
+	reg = <0x60>;
+	clocks = <&maxim_xtal>;
+	maxim,refout-load = <10>;
+
+	port {
+		max2175_0_ep: endpoint {
+			remote-endpoint = <&slave_rx_device>;
+		};
+	};
+
+};

Documentation/devicetree/bindings/property-units.txt

@@ -28,6 +28,7 @@ Electricity
 -ohms		: Ohms
 -micro-ohms	: micro Ohms
 -microvolt	: micro volts
+-picofarads	: picofarads
 
 Temperature
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