QCOM GSBI (General Serial Bus Interface) Driver

The GSBI controller is modeled as a node with zero or more child nodes, each
representing a serial sub-node device that is mux'd as part of the GSBI
configuration settings.  The mode setting will govern the input/output mode of
the 4 GSBI IOs.

Required properties:
- compatible:	Should contain "qcom,gsbi-v1.0.0"
- cell-index:	Should contain the GSBI index
- reg: Address range for GSBI registers
- clocks: required clock
- clock-names: must contain "iface" entry
- qcom,mode : indicates MUX value for configuration of the serial interface.
  Please reference dt-bindings/soc/qcom,gsbi.h for valid mux values.

Optional properties:
- qcom,crci : indicates CRCI MUX value for QUP CRCI ports.  Please reference
  dt-bindings/soc/qcom,gsbi.h for valid CRCI mux values.
- syscon-tcsr: indicates phandle of TCSR syscon node.  Required if child uses
  dma.

Required properties if child node exists:
- #address-cells: Must be 1
- #size-cells: Must be 1
- ranges: Must be present

Properties for children:

A GSBI controller node can contain 0 or more child nodes representing serial
devices.  These serial devices can be a QCOM UART, I2C controller, spi
controller, or some combination of aforementioned devices.

See the following for child node definitions:
Documentation/devicetree/bindings/i2c/qcom,i2c-qup.txt
Documentation/devicetree/bindings/spi/qcom,spi-qup.txt
Documentation/devicetree/bindings/serial/qcom,msm-uartdm.txt

Example for APQ8064:

#include <dt-bindings/soc/qcom,gsbi.h>

	gsbi4@16300000 {
		compatible = "qcom,gsbi-v1.0.0";
		cell-index = <4>;
		reg = <0x16300000 0x100>;
		clocks = <&gcc GSBI4_H_CLK>;
		clock-names = "iface";
		#address-cells = <1>;
		#size-cells = <1>;
		ranges;
		qcom,mode = <GSBI_PROT_I2C_UART>;
		qcom,crci = <GSBI_CRCI_QUP>;

		syscon-tcsr = <&tcsr>;

		/* child nodes go under here */

		i2c_qup4: i2c@16380000 {
			compatible = "qcom,i2c-qup-v1.1.1";
			reg = <0x16380000 0x1000>;
			interrupts = <0 153 0>;

			clocks = <&gcc GSBI4_QUP_CLK>, <&gcc GSBI4_H_CLK>;
			clock-names = "core", "iface";

			clock-frequency = <200000>;

			#address-cells = <1>;
			#size-cells = <0>;

		};

		uart4:	serial@16340000 {
			compatible = "qcom,msm-uartdm-v1.3", "qcom,msm-uartdm";
			reg = <0x16340000 0x1000>,
				<0x16300000 0x1000>;
			interrupts = <0 152 0x0>;
			clocks = <&gcc GSBI4_UART_CLK>, <&gcc GSBI4_H_CLK>;
			clock-names = "core", "iface";
		};
	};

	tcsr: syscon@1a400000 {
		compatible = "qcom,apq8064-tcsr", "syscon";
		reg = <0x1a400000 0x100>;
	};