* Spreadtrum MMC Host Controller

The Spreadtrum MMC Host Controller provides an interface for MMC, SD, and SDIO
types of memory cards. This file documents differences between the core
properties described by mmc.txt and the properties used by the Spreadtrum MMC
driver.

Required properties:
- compatible:
 should be "sprd,sdhc-r11p1",
 in order to compatible with MMC controller version
- reg: Registers location and length
- interrupts: exactly one interrupt specifier
- clock-names: The clock-names must have "sdio_clk", "sdio_clk_source" and
	       "sdio_ahb_enable".
	       The sdio for spreadtrum clock-names should contain sdio
	       clock node, source clk node ,sdio module enable clock node.
	       Clock-names is fixed in sdio drivers, and its purpose is to
	       constrain the order of clocks property.Consumers drivers
	       will use clock-names to match clock input names with clocks
	       specifiers.
- clocks: The freq of source clk connected to sdio.List of clock input name
	  strings sorted in the same order as the clocks property.

Optional properties:
- cd-gpios: specify GPIOs for card detection, see gpio binding.and that will
  delete "non-removable" in sprd driver code.
- vmmc-supply: phandle to input sdio core voltage
- vqmmc-supply: phandle to input sdio signal voltage
- voltage-ranges: VDD voltage ranges
- cap-mmc-hw-reset: eMMC hardware reset is supported
- sprd,dly-invert : clock data write line invert

*NOTE*
- The following properties are defined by spreadtrum. They are not standard
 properties of SDIO
- sprd,name: The name of the MMC device. For Example, "emmc", "wifi" and "sd".
  The capabilities of different MMC device can be set by this property in
  spreadtrum MMC host driver
- sprd,delay: This property value that obtained by hardware testing are fixed.
 prop-encoded-array <wr-dl rd-pos-dl rd-neg-dl> where:
    * wr-dl is the delay value between sdio clock signal and data write in
        milliseconds
    * rd-pos-dl is the delay value between sdio clock signal and posedge data
        read in milliseconds
    * rd-neg-dl is the delay value between sdio clock signal and negedge data
        read in milliseconds

Example:

sdio0: sdio@1100000 {
	compatible  = "sprd,sdhc-r11p1";
	reg = <0x1100000 0x1000>;
	interrupts = <GIC_SPI 19 IRQ_TYPE_LEVEL_HIGH>;
	clock-names = "sdio_clk", "sdio_clk_source","sdio_apb_enable";
	clocks = <&clk_sdio0>, <&clk_twpll_384m>, <&clk_ap_apb_gates 22>;
	status = "disabled";
};
