GENI based Qualcomm Universal Peripheral (QUP) 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.

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