Freescale Asynchronous Sample Rate Converter (ASRC) Controller

The Asynchronous Sample Rate Converter (ASRC) converts the sampling rate of a
signal associated with an input clock into a signal associated with a different
output clock. The driver currently works as a Front End of DPCM with other Back
Ends Audio controller such as ESAI, SSI and SAI. It has three pairs to support
three substreams within totally 10 channels.

Required properties:

  - compatible		: Compatible list, should contain one of the following
			  compatibles:
			  "fsl,imx35-asrc",
			  "fsl,imx53-asrc",
			  "fsl,imx8qm-asrc",
			  "fsl,imx8qxp-asrc",

  - 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		: Contains "rxa", "rxb", "rxc", "txa", "txb" and "txc".

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

  - clock-names		: Contains the following entries
	"mem"		  Peripheral access clock to access registers.
	"ipg"		  Peripheral clock to driver module.
	"asrck_<0-f>"	  Clock sources for input and output clock.
	"spba"		  The spba clock is required when ASRC 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,asrc-rate	: Defines a mutual sample rate used by DPCM Back Ends.

   - fsl,asrc-width	: Defines a mutual sample width used by DPCM Back Ends.

   - fsl,asrc-clk-map   : Defines clock map used in driver. which is required
			  by imx8qm/imx8qxp platform
			  <0> - select the map for asrc0 in imx8qm/imx8qxp
			  <1> - select the map for asrc1 in imx8qm/imx8qxp

Optional properties:

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

   - fsl,asrc-format	: Defines a mutual sample format used by DPCM Back
			  Ends, which can replace the fsl,asrc-width.
			  The value is 2 (S16_LE), or 6 (S24_LE).

Example:

asrc: asrc@2034000 {
	compatible = "fsl,imx53-asrc";
	reg = <0x02034000 0x4000>;
	interrupts = <0 50 IRQ_TYPE_LEVEL_HIGH>;
	clocks = <&clks 107>, <&clks 107>, <&clks 0>,
	       <&clks 0>, <&clks 0>, <&clks 0>, <&clks 0>,
	       <&clks 0>, <&clks 0>, <&clks 0>, <&clks 0>,
	       <&clks 0>, <&clks 0>, <&clks 0>, <&clks 0>,
	       <&clks 107>, <&clks 0>, <&clks 0>;
	clock-names = "mem", "ipg", "asrck0",
		"asrck_1", "asrck_2", "asrck_3", "asrck_4",
		"asrck_5", "asrck_6", "asrck_7", "asrck_8",
		"asrck_9", "asrck_a", "asrck_b", "asrck_c",
		"asrck_d", "asrck_e", "asrck_f";
	dmas = <&sdma 17 23 1>, <&sdma 18 23 1>, <&sdma 19 23 1>,
	     <&sdma 20 23 1>, <&sdma 21 23 1>, <&sdma 22 23 1>;
	dma-names = "rxa", "rxb", "rxc",
		"txa", "txb", "txc";
	fsl,asrc-rate  = <48000>;
	fsl,asrc-width = <16>;
};