ZTE VOU Display Controller

This is a display controller found on ZTE ZX296718 SoC.  It includes multiple
Graphic Layer (GL) and Video Layer (VL), two Mixers/Channels, and a few blocks
handling scaling, color space conversion etc.  VOU also integrates the support
for typical output devices, like HDMI, TV Encoder, VGA, and RGB LCD.

* Master VOU node

It must be the parent node of all the sub-device nodes.

Required properties:
 - compatible: should be "zte,zx296718-vou"
 - #address-cells: should be <1>
 - #size-cells: should be <1>
 - ranges: list of address translations between VOU and sub-devices

* VOU DPC device

Required properties:
 - compatible: should be "zte,zx296718-dpc"
 - reg: Physical base address and length of DPC register regions, one for each
   entry in 'reg-names'
 - reg-names: The names of register regions. The following regions are required:
	"osd"
	"timing_ctrl"
	"dtrc"
	"vou_ctrl"
	"otfppu"
 - interrupts: VOU DPC interrupt number to CPU
 - clocks: A list of phandle + clock-specifier pairs, one for each entry
   in 'clock-names'
 - clock-names: A list of clock names.  The following clocks are required:
	"aclk"
	"ppu_wclk"
	"main_wclk"
	"aux_wclk"

* HDMI output device

Required properties:
 - compatible: should be "zte,zx296718-hdmi"
 - reg: Physical base address and length of the HDMI device IO region
 - interrupts : HDMI interrupt number to CPU
 - clocks: A list of phandle + clock-specifier pairs, one for each entry
   in 'clock-names'
 - clock-names: A list of clock names.  The following clocks are required:
	"osc_cec"
	"osc_clk"
	"xclk"

* TV Encoder output device

Required properties:
 - compatible: should be "zte,zx296718-tvenc"
 - reg: Physical base address and length of the TVENC device IO region
 - zte,tvenc-power-control: the phandle to SYSCTRL block followed by two
   integer cells.  The first cell is the offset of SYSCTRL register used
   to control TV Encoder DAC power, and the second cell is the bit mask.

* VGA output device

Required properties:
 - compatible: should be "zte,zx296718-vga"
 - reg: Physical base address and length of the VGA device IO region
 - interrupts : VGA interrupt number to CPU
 - clocks: Phandle with clock-specifier pointing to VGA I2C clock.
 - clock-names: Must be "i2c_wclk".
 - zte,vga-power-control: the phandle to SYSCTRL block followed by two
   integer cells.  The first cell is the offset of SYSCTRL register used
   to control VGA DAC power, and the second cell is the bit mask.

Example:

vou: vou@1440000 {
	compatible = "zte,zx296718-vou";
	#address-cells = <1>;
	#size-cells = <1>;
	ranges = <0 0x1440000 0x10000>;

	dpc: dpc@0 {
		compatible = "zte,zx296718-dpc";
		reg = <0x0000 0x1000>, <0x1000 0x1000>,
		      <0x5000 0x1000>, <0x6000 0x1000>,
		      <0xa000 0x1000>;
		reg-names = "osd", "timing_ctrl",
			    "dtrc", "vou_ctrl",
			    "otfppu";
		interrupts = <GIC_SPI 81 IRQ_TYPE_LEVEL_HIGH>;
		clocks = <&topcrm VOU_ACLK>, <&topcrm VOU_PPU_WCLK>,
			 <&topcrm VOU_MAIN_WCLK>, <&topcrm VOU_AUX_WCLK>;
		clock-names = "aclk", "ppu_wclk",
			      "main_wclk", "aux_wclk";
	};

	vga: vga@8000 {
		compatible = "zte,zx296718-vga";
		reg = <0x8000 0x1000>;
		interrupts = <GIC_SPI 86 IRQ_TYPE_LEVEL_HIGH>;
		clocks = <&topcrm VGA_I2C_WCLK>;
		clock-names = "i2c_wclk";
		zte,vga-power-control = <&sysctrl 0x170 0xe0>;
	};

	hdmi: hdmi@c000 {
		compatible = "zte,zx296718-hdmi";
		reg = <0xc000 0x4000>;
		interrupts = <GIC_SPI 82 IRQ_TYPE_EDGE_RISING>;
		clocks = <&topcrm HDMI_OSC_CEC>,
			 <&topcrm HDMI_OSC_CLK>,
			 <&topcrm HDMI_XCLK>;
		clock-names = "osc_cec", "osc_clk", "xclk";
	};

	tvenc: tvenc@2000 {
		compatible = "zte,zx296718-tvenc";
		reg = <0x2000 0x1000>;
		zte,tvenc-power-control = <&sysctrl 0x170 0x10>;
	};
};