* Freescale (Enhanced) Configurable Serial Peripheral Interface
  (CSPI/eCSPI) for i.MX

Required properties:
- compatible :
  - "fsl,imx1-cspi" for SPI compatible with the one integrated on i.MX1
  - "fsl,imx21-cspi" for SPI compatible with the one integrated on i.MX21
  - "fsl,imx27-cspi" for SPI compatible with the one integrated on i.MX27
  - "fsl,imx31-cspi" for SPI compatible with the one integrated on i.MX31
  - "fsl,imx35-cspi" for SPI compatible with the one integrated on i.MX35
  - "fsl,imx51-ecspi" for SPI compatible with the one integrated on i.MX51
  - "fsl,imx53-ecspi" for SPI compatible with the one integrated on i.MX53 and later Soc
- reg : Offset and length of the register set for the device
- interrupts : Should contain CSPI/eCSPI interrupt
- cs-gpios : Specifies the gpio pins to be used for chipselects.
- clocks : Clock specifiers for both ipg and per clocks.
- clock-names : Clock names should include both "ipg" and "per"
See the clock consumer binding,
	Documentation/devicetree/bindings/clock/clock-bindings.txt
- dmas: DMA specifiers for tx and rx dma. See the DMA client binding,
		Documentation/devicetree/bindings/dma/dma.txt
- dma-names: DMA request names should include "tx" and "rx" if present.

Obsolete properties:
- fsl,spi-num-chipselects : Contains the number of the chipselect

Optional properties:
- fsl,spi-rdy-drctl: Integer, representing the value of DRCTL, the register
controlling the SPI_READY handling. Note that to enable the DRCTL consideration,
the SPI_READY mode-flag needs to be set too.
Valid values are: 0 (disabled), 1 (edge-triggered burst) and 2 (level-triggered burst).

Example:

ecspi@70010000 {
	#address-cells = <1>;
	#size-cells = <0>;
	compatible = "fsl,imx51-ecspi";
	reg = <0x70010000 0x4000>;
	interrupts = <36>;
	cs-gpios = <&gpio3 24 0>, /* GPIO3_24 */
		   <&gpio3 25 0>; /* GPIO3_25 */
	dmas = <&sdma 3 7 1>, <&sdma 4 7 2>;
	dma-names = "rx", "tx";
	fsl,spi-rdy-drctl = <1>;
};