* MTK MMC controller

The MTK  MSDC can act as a MMC controller
to support MMC, SD, and SDIO types of memory cards.

This file documents differences between the core properties in mmc.txt
and the properties used by the msdc driver.

Required properties:
- compatible: Should be "mediatek,mt8173-mmc","mediatek,mt8135-mmc"
- interrupts: Should contain MSDC interrupt number
- clocks: MSDC source clock, HCLK
- clock-names: "source", "hclk"
- pinctrl-names: should be "default", "state_uhs"
- pinctrl-0: should contain default/high speed pin ctrl
- pinctrl-1: should contain uhs mode pin ctrl
- vmmc-supply: power to the Core
- vqmmc-supply: power to the IO

Optional properties:
- assigned-clocks: PLL of the source clock
- assigned-clock-parents: parent of source clock, used for HS400 mode to get 400Mhz source clock
- hs400-ds-delay: HS400 DS delay setting
- mediatek,hs200-cmd-int-delay: HS200 command internal delay setting.
				This field has total 32 stages.
				The value is an integer from 0 to 31.
- mediatek,hs400-cmd-int-delay: HS400 command internal delay setting
				This field has total 32 stages.
				The value is an integer from 0 to 31.
- mediatek,hs400-cmd-resp-sel-rising:  HS400 command response sample selection
				       If present,HS400 command responses are sampled on rising edges.
				       If not present,HS400 command responses are sampled on falling edges.

Examples:
mmc0: mmc@11230000 {
	compatible = "mediatek,mt8173-mmc", "mediatek,mt8135-mmc";
	reg = <0 0x11230000 0 0x108>;
	interrupts = <GIC_SPI 39 IRQ_TYPE_LEVEL_LOW>;
	vmmc-supply = <&mt6397_vemc_3v3_reg>;
	vqmmc-supply = <&mt6397_vio18_reg>;
	clocks = <&pericfg CLK_PERI_MSDC30_0>,
	         <&topckgen CLK_TOP_MSDC50_0_H_SEL>;
	clock-names = "source", "hclk";
	pinctrl-names = "default", "state_uhs";
	pinctrl-0 = <&mmc0_pins_default>;
	pinctrl-1 = <&mmc0_pins_uhs>;
	assigned-clocks = <&topckgen CLK_TOP_MSDC50_0_SEL>;
	assigned-clock-parents = <&topckgen CLK_TOP_MSDCPLL_D2>;
	hs400-ds-delay = <0x14015>;
	mediatek,hs200-cmd-int-delay = <26>;
	mediatek,hs400-cmd-int-delay = <14>;
	mediatek,hs400-cmd-resp-sel-rising;
};