dt-bindings: iio: adc: Add docs for ad7124

Analog Devices AD7124 ADC device driver

Required properties for the AD7124:

	- compatible: Must be one of "adi,ad7124-4" or "adi,ad7124-8"

	- reg: SPI chip select number for the device

	- spi-max-frequency: Max SPI frequency to use

		see: Documentation/devicetree/bindings/spi/spi-bus.txt

	- clocks: phandle to the master clock (mclk)

		see: Documentation/devicetree/bindings/clock/clock-bindings.txt

	- clock-names: Must be "mclk".

	- interrupts: IRQ line for the ADC

		see: Documentation/devicetree/bindings/interrupt-controller/interrupts.txt

	  Required properties:

		* #address-cells: Must be 1.

		* #size-cells: Must be 0.

	  Subnode(s) represent the external channels which are connected to the ADC.

	  Each subnode represents one channel and has the following properties:

		Required properties:

			* reg: The channel number. It can have up to 4 channels on ad7124-4

			  and 8 channels on ad7124-8, numbered from 0 to 15.

			* diff-channels: see: Documentation/devicetree/bindings/iio/adc/adc.txt

		Optional properties:

			* bipolar: see: Documentation/devicetree/bindings/iio/adc/adc.txt

			* adi,reference-select: Select the reference source to use when

			  converting on the the specific channel. Valid values are:

			  0: REFIN1(+)/REFIN1(−).

			  1: REFIN2(+)/REFIN2(−).

			  3: AVDD

			  If this field is left empty, internal reference is selected.

Optional properties:

	- refin1-supply: refin1 supply can be used as reference for conversion.

	- refin2-supply: refin2 supply can be used as reference for conversion.

	- avdd-supply: avdd supply can be used as reference for conversion.

Example:

	adc@0 {

		compatible = "adi,ad7124-4";

		reg = <0>;

		spi-max-frequency = <5000000>;

		interrupts = <25 2>;

		interrupt-parent = <&gpio>;

		refin1-supply = <&adc_vref>;

		clocks = <&ad7124_mclk>;

		clock-names = "mclk";

		#address-cells = <1>;

		#size-cells = <0>;

		channel@0 {

			reg = <0>;

			diff-channels = <0 1>;

			adi,reference-select = <0>;

		};

		channel@1 {

			reg = <1>;

			bipolar;

			diff-channels = <2 3>;

			adi,reference-select = <0>;

		};

		channel@2 {

			reg = <2>;

			diff-channels = <4 5>;

		};

		channel@3 {

			reg = <3>;

			diff-channels = <6 7>;

		};

	};

W:	http://ez.analog.com/community/linux-device-drivers

S:	Supported

F:	drivers/iio/adc/ad7124.c

F:	Documentation/devicetree/bindings/iio/adc/adi,ad7124.txt

ANALOG DEVICES INC AD9389B DRIVER

M:	Hans Verkuil <hans.verkuil@cisco.com>