linux/Documentation/devicetree/bindings/mmc/exynos-dw-mshc.txt
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   1* Samsung Exynos specific extensions to the Synopsis Designware Mobile
   2  Storage Host Controller
   3
   4The Synopsis designware mobile storage host controller is used to interface
   5a SoC with storage medium such as eMMC or SD/MMC cards. This file documents
   6differences between the core Synopsis dw mshc controller properties described
   7by synopsis-dw-mshc.txt and the properties used by the Samsung Exynos specific
   8extensions to the Synopsis Designware Mobile Storage Host Controller.
   9
  10Required Properties:
  11
  12* compatible: should be
  13        - "samsung,exynos4210-dw-mshc": for controllers with Samsung Exynos4210
  14          specific extensions.
  15        - "samsung,exynos4412-dw-mshc": for controllers with Samsung Exynos4412
  16          specific extensions.
  17        - "samsung,exynos5250-dw-mshc": for controllers with Samsung Exynos5250
  18          specific extensions.
  19
  20* samsung,dw-mshc-ciu-div: Specifies the divider value for the card interface
  21  unit (ciu) clock. This property is applicable only for Exynos5 SoC's and
  22  ignored for Exynos4 SoC's. The valid range of divider value is 0 to 7.
  23
  24* samsung,dw-mshc-sdr-timing: Specifies the value of CIU clock phase shift value
  25  in transmit mode and CIU clock phase shift value in receive mode for single
  26  data rate mode operation. Refer notes below for the order of the cells and the
  27  valid values.
  28
  29* samsung,dw-mshc-ddr-timing: Specifies the value of CUI clock phase shift value
  30  in transmit mode and CIU clock phase shift value in receive mode for double
  31  data rate mode operation. Refer notes below for the order of the cells and the
  32  valid values.
  33
  34  Notes for the sdr-timing and ddr-timing values:
  35
  36    The order of the cells should be
  37      - First Cell: CIU clock phase shift value for tx mode.
  38      - Second Cell: CIU clock phase shift value for rx mode.
  39
  40    Valid values for SDR and DDR CIU clock timing for Exynos5250:
  41      - valid value for tx phase shift and rx phase shift is 0 to 7.
  42      - when CIU clock divider value is set to 3, all possible 8 phase shift
  43        values can be used.
  44      - if CIU clock divider value is 0 (that is divide by 1), both tx and rx
  45        phase shift clocks should be 0.
  46
  47Required properties for a slot:
  48
  49* gpios: specifies a list of gpios used for command, clock and data bus. The
  50  first gpio is the command line and the second gpio is the clock line. The
  51  rest of the gpios (depending on the bus-width property) are the data lines in
  52  no particular order. The format of the gpio specifier depends on the gpio
  53  controller.
  54
  55Example:
  56
  57  The MSHC controller node can be split into two portions, SoC specific and
  58  board specific portions as listed below.
  59
  60        dwmmc0@12200000 {
  61                compatible = "samsung,exynos5250-dw-mshc";
  62                reg = <0x12200000 0x1000>;
  63                interrupts = <0 75 0>;
  64                #address-cells = <1>;
  65                #size-cells = <0>;
  66        };
  67
  68        dwmmc0@12200000 {
  69                num-slots = <1>;
  70                supports-highspeed;
  71                broken-cd;
  72                fifo-depth = <0x80>;
  73                card-detect-delay = <200>;
  74                samsung,dw-mshc-ciu-div = <3>;
  75                samsung,dw-mshc-sdr-timing = <2 3>;
  76                samsung,dw-mshc-ddr-timing = <1 2>;
  77
  78                slot@0 {
  79                        reg = <0>;
  80                        bus-width = <8>;
  81                        gpios = <&gpc0 0 2 0 3>, <&gpc0 1 2 0 3>,
  82                                <&gpc1 0 2 3 3>, <&gpc1 1 2 3 3>,
  83                                <&gpc1 2 2 3 3>, <&gpc1 3 2 3 3>,
  84                                <&gpc0 3 2 3 3>, <&gpc0 4 2 3 3>,
  85                                <&gpc0 5 2 3 3>, <&gpc0 6 2 3 3>;
  86                };
  87        };
  88