Freescale Enhanced Serial Audio Interface (ESAI) Controller

The Enhanced Serial Audio Interface (ESAI) provides a full-duplex serial port
for serial communication with a variety of serial devices, including industry
standard codecs, Sony/Phillips Digital Interface (S/PDIF) transceivers, and
other DSPs. It has up to six transmitters and four receivers.

Required properties:

  - compatible		: Compatible list, should contain one of the following
			  compatibles:
			  "fsl,imx35-esai",
			  "fsl,vf610-esai",
			  "fsl,imx6ull-esai",
			  "fsl,imx8qm-esai",

  - reg			: Offset and length of the register set for the device.

  - interrupts		: Contains the spdif interrupt.

  - dmas		: Generic dma devicetree binding as described in
			  Documentation/devicetree/bindings/dma/dma.txt.

  - dma-names		: Two dmas have to be defined, "tx" and "rx".

  - clocks		: Contains an entry for each entry in clock-names.

  - clock-names		: Includes the following entries:
	"core"		  The core clock used to access registers
	"extal"		  The esai baud clock for esai controller used to
			  derive HCK, SCK and FS.
	"fsys"		  The system clock derived from ahb clock used to
			  derive HCK, SCK and FS.
	"spba"		  The spba clock is required when ESAI is placed as a
			  bus slave of the Shared Peripheral Bus and when two
			  or more bus masters (CPU, DMA or DSP) try to access
			  it. This property is optional depending on the SoC
			  design.

  - fsl,fifo-depth	: The number of elements in the transmit and receive
			  FIFOs. This number is the maximum allowed value for
			  TFCR[TFWM] or RFCR[RFWM].

  - fsl,esai-synchronous: This is a boolean property. If present, indicating
			  that ESAI would work in the synchronous mode, which
			  means all the settings for Receiving would be
			  duplicated from Transmition related registers.

Optional properties:

  - big-endian		: If this property is absent, the native endian mode
			  will be in use as default, or the big endian mode
			  will be in use for all the device registers.

Example:

esai: esai@2024000 {
	compatible = "fsl,imx35-esai";
	reg = <0x02024000 0x4000>;
	interrupts = <0 51 0x04>;
	clocks = <&clks 208>, <&clks 118>, <&clks 208>;
	clock-names = "core", "extal", "fsys";
	dmas = <&sdma 23 21 0>, <&sdma 24 21 0>;
	dma-names = "rx", "tx";
	fsl,fifo-depth = <128>;
	fsl,esai-synchronous;
	big-endian;
};