linux/linux-5.4.31/Documentation/devicetree/bindings/mmc/nvidia,tegra20-sdhci.txt

* NVIDIA Tegra Secure Digital Host Controller

This controller on Tegra family SoCs 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 sdhci-tegra driver.

Required properties:
- compatible : should be one of:
  - "nvidia,tegra20-sdhci": for Tegra20
  - "nvidia,tegra30-sdhci": for Tegra30
  - "nvidia,tegra114-sdhci": for Tegra114
  - "nvidia,tegra124-sdhci": for Tegra124 and Tegra132
  - "nvidia,tegra210-sdhci": for Tegra210
  - "nvidia,tegra186-sdhci": for Tegra186
  - "nvidia,tegra194-sdhci": for Tegra194
- clocks : Must contain one entry, for the module clock.
  See ../clocks/clock-bindings.txt for details.
- resets : Must contain an entry for each entry in reset-names.
  See ../reset/reset.txt for details.
- reset-names : Must include the following entries:
  - sdhci

Optional properties:
- power-gpios : Specify GPIOs for power control

Example:

sdhci@c8000200 {
	compatible = "nvidia,tegra20-sdhci";
	reg = <0xc8000200 0x200>;
	interrupts = <47>;
	clocks = <&tegra_car 14>;
	resets = <&tegra_car 14>;
	reset-names = "sdhci";
	cd-gpios = <&gpio 69 0>; /* gpio PI5 */
	wp-gpios = <&gpio 57 0>; /* gpio PH1 */
	power-gpios = <&gpio 155 0>; /* gpio PT3 */
	bus-width = <8>;
};

Optional properties for Tegra210, Tegra186 and Tegra194:
- pinctrl-names, pinctrl-0, pinctrl-1 : Specify pad voltage
  configurations. Valid pinctrl-names are "sdmmc-3v3" and "sdmmc-1v8"
  for controllers supporting multiple voltage levels. The order of names
  should correspond to the pin configuration states in pinctrl-0 and
  pinctrl-1.
- pinctrl-names : "sdmmc-3v3-drv" and "sdmmc-1v8-drv" are applicable for
  Tegra210 where pad config registers are in the pinmux register domain
  for pull-up-strength and pull-down-strength values configuration when
  using pads at 3V3 and 1V8 levels.
- nvidia,only-1-8-v : The presence of this property indicates that the
  controller operates at a 1.8 V fixed I/O voltage.
- nvidia,pad-autocal-pull-up-offset-3v3,
  nvidia,pad-autocal-pull-down-offset-3v3 : Specify drive strength
  calibration offsets for 3.3 V signaling modes.
- nvidia,pad-autocal-pull-up-offset-1v8,
  nvidia,pad-autocal-pull-down-offset-1v8 : Specify drive strength
  calibration offsets for 1.8 V signaling modes.
- nvidia,pad-autocal-pull-up-offset-3v3-timeout,
  nvidia,pad-autocal-pull-down-offset-3v3-timeout : Specify drive
  strength used as a fallback in case the automatic calibration times
  out on a 3.3 V signaling mode.
- nvidia,pad-autocal-pull-up-offset-1v8-timeout,
  nvidia,pad-autocal-pull-down-offset-1v8-timeout : Specify drive
  strength used as a fallback in case the automatic calibration times
  out on a 1.8 V signaling mode.
- nvidia,pad-autocal-pull-up-offset-sdr104,
  nvidia,pad-autocal-pull-down-offset-sdr104 : Specify drive strength
  calibration offsets for SDR104 mode.
- nvidia,pad-autocal-pull-up-offset-hs400,
  nvidia,pad-autocal-pull-down-offset-hs400 : Specify drive strength
  calibration offsets for HS400 mode.
- nvidia,default-tap : Specify the default inbound sampling clock
  trimmer value for non-tunable modes.
- nvidia,default-trim : Specify the default outbound clock trimmer
  value.
- nvidia,dqs-trim : Specify DQS trim value for HS400 timing

  Notes on the pad calibration pull up and pulldown offset values:
    - The property values are drive codes which are programmed into the
      PD_OFFSET and PU_OFFSET sections of the
      SDHCI_TEGRA_AUTO_CAL_CONFIG register.
    - A higher value corresponds to higher drive strength. Please refer
      to the reference manual of the SoC for correct values.
    - The SDR104 and HS400 timing specific values are used in
      corresponding modes if specified.

  Notes on tap and trim values:
    - The values are used for compensating trace length differences
      by adjusting the sampling point.
    - The values are programmed to the Vendor Clock Control Register.
      Please refer to the reference manual of the SoC for correct
      values.
    - The DQS trim values are only used on controllers which support
      HS400 timing. Only SDMMC4 on Tegra210 and Tegra 186 supports
      HS400.

Example:
sdhci@700b0000 {
	compatible = "nvidia,tegra210-sdhci", "nvidia,tegra124-sdhci";
	reg = <0x0 0x700b0000 0x0 0x200>;
	interrupts = <GIC_SPI 14 IRQ_TYPE_LEVEL_HIGH>;
	clocks = <&tegra_car TEGRA210_CLK_SDMMC1>;
	clock-names = "sdhci";
	resets = <&tegra_car 14>;
	reset-names = "sdhci";
	pinctrl-names = "sdmmc-3v3", "sdmmc-1v8";
	pinctrl-0 = <&sdmmc1_3v3>;
	pinctrl-1 = <&sdmmc1_1v8>;
	nvidia,pad-autocal-pull-up-offset-3v3 = <0x00>;
	nvidia,pad-autocal-pull-down-offset-3v3 = <0x7d>;
	nvidia,pad-autocal-pull-up-offset-1v8 = <0x7b>;
	nvidia,pad-autocal-pull-down-offset-1v8 = <0x7b>;
	status = "disabled";
};