* Samsung's SDHCI Controller device tree bindings

Samsung's SDHCI controller is used as a connectivity interface with external
MMC, SD and eMMC storage mediums.

Required SoC Specific Properties:
- compatible: should be one of the following
  - "samsung,s3c6410-sdhci": For controllers compatible with s3c6410 sdhci
    controller.
  - "samsung,exynos4210-sdhci": For controller compatible with Exynos4 sdhci
    controller.

- reg: physical base address of the controller and length of memory mapped
  region.

- interrupts: The interrupt number to the cpu. The interrupt specifier format
  depends on the interrupt controller.


Required Board Specific Properties:
- gpios: Should specify the gpios used for clock, command and data lines. The
  gpio specifier format depends on the gpio controller. Note: There is no
  particular order in which the gpio's have to be listed.


Optional Board Specific Properties:
- samsung,sdhci-bus-width: Number of data lines connected to the controller.
  Note: This excludes the clock,command and card detect lines. If this property
  is not specified, default value is 1.

- samsung,cd-gpio-invert: If 'samsung,sdhci-cd-gpio' card detect method is
  selected, this property can be optionally specified to invert the value of
  external card detect gpio line.

- One of the following properties for card detect type.
  - samsung,sdhci-cd-internal: Card detect line from the card slot  is
    connected to the card detect pad of the sdhci controller. A gpio is
    used for this connection (with possible pin function settings).
  - samsung,sdhci-cd-gpio: A gpio line (with possible pin function settings)
    is used a card detect line. This gpio line is not connected to card detect
    pad of the sdhci controller.
  - samsung,sdhci-cd-none: There is no card detect line. Polling is used to
    detect the presence of the card. (DEFAULT, if no card detect property
    is specified).
  - samsung,sdhci-cd-permanent: There is no card detect line. The card is
    permanently connected to the sdhci controller.

- gpio-cd: The gpio to be used as card detect line for
  'samsung,sdhci-cd-internal' or 'samsung,sdhci-cd-gpio' card detection method.
  The gpio specifier format depends on the gpio controller.

Example:
	sdhci@12530000 {
		compatible = "samsung,exynos4210-sdhci";
		reg = <0x12530000 0x100>;
		interrupts = <139>;
		samsung,sdhci-bus-width = <4>;
		samsung,sdhci-cd-internal;
		gpio-cd = <&gpk2 2 2 3 3>;
		gpios = <&gpk2 0 2 0 3>,  /* clock line */
			<&gpk2 1 2 0 3>,  /* command line */
			<&gpk2 3 2 3 3>,  /* data line 0 */
			<&gpk2 4 2 3 3>,  /* data line 1 */
			<&gpk2 5 2 3 3>,  /* data line 2 */
			<&gpk2 6 2 3 3>;  /* data line 3 */
	};

	Note: This example shows both SoC specific and board specific properties
	in a single device node. The properties can be actually be seperated
	into SoC specific node and board specific node.
