dt-bindings: spi: Add device tree documentation for SPI GENI driver

GENI based Qualcomm Technologies Inc Universal Peripheral version 3 (QUPv3)

					Serial Peripheral Interface (SPI)

The QUP v3 core is a GENI based AHB slave that provides a common data path

(an output FIFO and an input FIFO) for serial peripheral interface (SPI)

mini-core.

SPI in master mode supports up to 50MHz, up to four chip selects, programmable

data path from 4 bits to 32 bits and numerous protocol variants.

Required properties:

- compatible:	  Should contain "qcom,spi-geni"

- reg:		  Should contain base register location and length

- interrupts:	  Interrupt number used by this controller

- clocks:	  Should contain the core clock and the AHB clock.

- clock-names:	  Should be "core" for the core clock and "iface" for the

		  AHB clock.

- pinctrl-names:  Property should contain "default" and "sleep" for the

		  pin configurations during the usecase and during idle.

- pinctrl-x:	  phandle to the default/sleep pin configurations.

- #address-cells: Number of cells required to define a chip select

		  address on the SPI bus. Should be set to 1.

- #size-cells:	  Should be zero.

- spi-max-frequency: Specifies maximum SPI clock frequency,

		     Units - Hz. Definition as per

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

- qcom,wrapper-core: Wrapper QUPv3 core containing this SPI controller.

Optional properties:

- qcom,rt:	Specifies if the framework worker thread for this

		controller device should have "real-time" priority.

- qcom,disable-autosuspend: Specifies to disable runtime PM auto suspend.

SPI slave nodes must be children of the SPI master node and can contain

the following properties.

Required properties:

- compatible:     Should contain:

                  "qcom,spi-msm-codec-slave" for external codec control

- reg:            Chip select address of device.

- spi-max-frequency: Maximum SPI clocking speed of device in Hz.

Optional properties:

- spi-cpha:       Empty property indicating device requires

                  shifted clock phase (CPHA) mode.

- qcom,slv-ctrl : Set this flag to configure QUPV3 as SPI slave controller.

Other optional properties described in

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

Example:

	qupv3_spi10: spi@a84000 {

		compatible = "qcom,spi-geni";

		#address-cells = <1>;

		#size-cells = <0>;

		reg = <0xa84000 0x4000>;

		reg-names = "se_phys";

		clock-names = "se-clk", "m-ahb", "s-ahb";

		clocks = <&clock_gcc GCC_QUPV3_WRAP0_S0_CLK>,

			<&clock_gcc GCC_QUPV3_WRAP_0_M_AHB_CLK>,

			<&clock_gcc GCC_QUPV3_WRAP_0_S_AHB_CLK>;

		pinctrl-names = "default", "sleep";

		pinctrl-0 = <&qup_1_spi_2_active>;

		pinctrl-1 = <&qup_1_spi_2_sleep>;

		interrupts = <GIC_SPI 354 0>;

		spi-max-frequency = <19200000>;

		qcom,wrapper-core = <&qupv3_0>;

		dev@0 {

			compatible = "dummy,slave";

			reg = <0>;

			spi-max-frequency = <9600000>;

		};

	};