MT8173 xHCI

The device node for Mediatek SOC USB3.0 host controller

There are two scenarios: the first one only supports xHCI driver;
the second one supports dual-role mode, and the host is based on xHCI
driver. Take account of backward compatibility, we divide bindings
into two parts.

1st: only supports xHCI driver
------------------------------------------------------------------------

Required properties:
 - compatible : should be "mediatek,<soc-model>-xhci", "mediatek,mtk-xhci",
	soc-model is the name of SoC, such as mt8173, mt2712 etc, when using
	"mediatek,mtk-xhci" compatible string, you need SoC specific ones in
	addition, one of:
	- "mediatek,mt8173-xhci"
 - reg : specifies physical base address and size of the registers
 - reg-names: should be "mac" for xHCI MAC and "ippc" for IP port control
 - interrupts : interrupt used by the controller
 - power-domains : a phandle to USB power domain node to control USB's
	mtcmos
 - vusb33-supply : regulator of USB avdd3.3v

 - clocks : a list of phandle + clock-specifier pairs, one for each
	entry in clock-names
 - clock-names : must contain
	"sys_ck": controller clock used by normal mode,
	the following ones are optional:
	"ref_ck": reference clock used by low power mode etc,
	"mcu_ck": mcu_bus clock for register access,
	"dma_ck": dma_bus clock for data transfer by DMA,
	"xhci_ck": controller clock

 - phys : see usb-hcd.yaml in the current directory

Optional properties:
 - wakeup-source : enable USB remote wakeup;
 - mediatek,syscon-wakeup : phandle to syscon used to access the register
	of the USB wakeup glue layer between xHCI and SPM; it depends on
	"wakeup-source", and has two arguments:
	- the first one : register base address of the glue layer in syscon;
	- the second one : hardware version of the glue layer
		- 1 : used by mt8173 etc
		- 2 : used by mt2712 etc
 - mediatek,u3p-dis-msk : mask to disable u3ports, bit0 for u3port0,
	bit1 for u3port1, ... etc;
 - vbus-supply : reference to the VBUS regulator;
 - usb3-lpm-capable : supports USB3.0 LPM
 - pinctrl-names : a pinctrl state named "default" must be defined
 - pinctrl-0 : pin control group
	See: Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt
 - imod-interval-ns: default interrupt moderation interval is 5000ns

additionally the properties from usb-hcd.yaml (in the current directory) are
supported.

Example:
usb30: usb@11270000 {
	compatible = "mediatek,mt8173-xhci";
	reg = <0 0x11270000 0 0x1000>,
	      <0 0x11280700 0 0x0100>;
	reg-names = "mac", "ippc";
	interrupts = <GIC_SPI 115 IRQ_TYPE_LEVEL_LOW>;
	power-domains = <&scpsys MT8173_POWER_DOMAIN_USB>;
	clocks = <&topckgen CLK_TOP_USB30_SEL>, <&clk26m>,
		 <&pericfg CLK_PERI_USB0>,
		 <&pericfg CLK_PERI_USB1>;
	clock-names = "sys_ck", "ref_ck";
	phys = <&phy_port0 PHY_TYPE_USB3>,
	       <&phy_port1 PHY_TYPE_USB2>;
	vusb33-supply = <&mt6397_vusb_reg>;
	vbus-supply = <&usb_p1_vbus>;
	usb3-lpm-capable;
	mediatek,syscon-wakeup = <&pericfg 0x400 1>;
	wakeup-source;
	imod-interval-ns = <10000>;
};

2nd: dual-role mode with xHCI driver
------------------------------------------------------------------------

In the case, xhci is added as subnode to mtu3. An example and the DT binding
details of mtu3 can be found in:
Documentation/devicetree/bindings/usb/mediatek,mtu3.txt

Required properties:
 - compatible : should be "mediatek,<soc-model>-xhci", "mediatek,mtk-xhci",
	soc-model is the name of SoC, such as mt8173, mt2712 etc, when using
	"mediatek,mtk-xhci" compatible string, you need SoC specific ones in
	addition, one of:
	- "mediatek,mt8173-xhci"
 - reg : specifies physical base address and size of the registers
 - reg-names: should be "mac" for xHCI MAC
 - interrupts : interrupt used by the host controller
 - power-domains : a phandle to USB power domain node to control USB's
	mtcmos
 - vusb33-supply : regulator of USB avdd3.3v

 - clocks : a list of phandle + clock-specifier pairs, one for each
	entry in clock-names
 - clock-names : must contain "sys_ck", and the following ones are optional:
	"ref_ck", "mcu_ck" and "dma_ck", "xhci_ck"

Optional properties:
 - vbus-supply : reference to the VBUS regulator;
 - usb3-lpm-capable : supports USB3.0 LPM

Example:
usb30: usb@11270000 {
	compatible = "mediatek,mt8173-xhci";
	reg = <0 0x11270000 0 0x1000>;
	reg-names = "mac";
	interrupts = <GIC_SPI 115 IRQ_TYPE_LEVEL_LOW>;
	power-domains = <&scpsys MT8173_POWER_DOMAIN_USB>;
	clocks = <&topckgen CLK_TOP_USB30_SEL>, <&clk26m>;
	clock-names = "sys_ck", "ref_ck";
	vusb33-supply = <&mt6397_vusb_reg>;
	usb3-lpm-capable;
};