xref: /kernel/linux/linux-5.10/Documentation/devicetree/bindings/mmc/exynos-dw-mshc.txt

* Samsung Exynos specific extensions to the Synopsys Designware Mobile
  Storage Host Controller

The Synopsys designware mobile storage host controller is used to interface
a SoC with storage medium such as eMMC or SD/MMC cards. This file documents
differences between the core Synopsys dw mshc controller properties described
by synopsys-dw-mshc.txt and the properties used by the Samsung Exynos specific
extensions to the Synopsys Designware Mobile Storage Host Controller.

Required Properties:

* compatible: should be
	- "samsung,exynos4210-dw-mshc": for controllers with Samsung Exynos4210
	  specific extensions.
	- "samsung,exynos4412-dw-mshc": for controllers with Samsung Exynos4412
	  specific extensions.
	- "samsung,exynos5250-dw-mshc": for controllers with Samsung Exynos5250
	  specific extensions.
	- "samsung,exynos5420-dw-mshc": for controllers with Samsung Exynos5420
	  specific extensions.
	- "samsung,exynos7-dw-mshc": for controllers with Samsung Exynos7
	  specific extensions.
	- "samsung,exynos7-dw-mshc-smu": for controllers with Samsung Exynos7
	  specific extensions having an SMU.

* samsung,dw-mshc-ciu-div: Specifies the divider value for the card interface
  unit (ciu) clock. This property is applicable only for Exynos5 SoC's and
  ignored for Exynos4 SoC's. The valid range of divider value is 0 to 7.

* samsung,dw-mshc-sdr-timing: Specifies the value of CIU clock phase shift value
  in transmit mode and CIU clock phase shift value in receive mode for single
  data rate mode operation. Refer notes below for the order of the cells and the
  valid values.

* samsung,dw-mshc-ddr-timing: Specifies the value of CUI clock phase shift value
  in transmit mode and CIU clock phase shift value in receive mode for double
  data rate mode operation. Refer notes below for the order of the cells and the
  valid values.
* samsung,dw-mshc-hs400-timing: Specifies the value of CIU TX and RX clock phase
  shift value for hs400 mode operation.

  Notes for the sdr-timing and ddr-timing values:

    The order of the cells should be
      - First Cell: CIU clock phase shift value for tx mode.
      - Second Cell: CIU clock phase shift value for rx mode.

    Valid values for SDR and DDR CIU clock timing for Exynos5250:
      - valid value for tx phase shift and rx phase shift is 0 to 7.
      - when CIU clock divider value is set to 3, all possible 8 phase shift
        values can be used.
      - if CIU clock divider value is 0 (that is divide by 1), both tx and rx
        phase shift clocks should be 0.

* samsung,read-strobe-delay: RCLK (Data strobe) delay to control HS400 mode
  (Latency value for delay line in Read path)

Required properties for a slot (Deprecated - Recommend to use one slot per host):

* gpios: specifies a list of gpios used for command, clock and data bus. The
  first gpio is the command line and the second gpio is the clock line. The
  rest of the gpios (depending on the bus-width property) are the data lines in
  no particular order. The format of the gpio specifier depends on the gpio
  controller.
(Deprecated - Refer to Documentation/devicetree/bindings/pinctrl/samsung-pinctrl.txt)

Example:

  The MSHC controller node can be split into two portions, SoC specific and
  board specific portions as listed below.

	dwmmc0@12200000 {
		compatible = "samsung,exynos5250-dw-mshc";
		reg = <0x12200000 0x1000>;
		interrupts = <0 75 0>;
		#address-cells = <1>;
		#size-cells = <0>;
	};

	dwmmc0@12200000 {
		cap-mmc-highspeed;
		cap-sd-highspeed;
		broken-cd;
		fifo-depth = <0x80>;
		card-detect-delay = <200>;
		samsung,dw-mshc-ciu-div = <3>;
		samsung,dw-mshc-sdr-timing = <2 3>;
		samsung,dw-mshc-ddr-timing = <1 2>;
		samsung,dw-mshc-hs400-timing = <0 2>;
		samsung,read-strobe-delay = <90>;
		bus-width = <8>;
	};