dt-bindings: mmc: Convert pwrseq to json-schema

* The simple eMMC hardware reset provider

The purpose of this driver is to perform standard eMMC hw reset

procedure, as described by Jedec 4.4 specification. This procedure is

performed just after MMC core enabled power to the given mmc host (to

fix possible issues if bootloader has left eMMC card in initialized or

unknown state), and before performing complete system reboot (also in

case of emergency reboot call). The latter is needed on boards, which

doesn't have hardware reset logic connected to emmc card and (limited or

broken) ROM bootloaders are unable to read second stage from the emmc

card if the card is left in unknown or already initialized state.

Required properties:

- compatible : contains "mmc-pwrseq-emmc".

- reset-gpios : contains a GPIO specifier. The reset GPIO is asserted

	and then deasserted to perform eMMC card reset. To perform

	reset procedure as described in Jedec 4.4 specification, the

	gpio line should be defined as GPIO_ACTIVE_LOW.

Example:

	sdhci0_pwrseq {

		compatible = "mmc-pwrseq-emmc";

		reset-gpios = <&gpio1 12 GPIO_ACTIVE_LOW>;

	}

# SPDX-License-Identifier: GPL-2.0

%YAML 1.2

---

$id: http://devicetree.org/schemas/mmc/mmc-pwrseq-emmc.yaml#

$schema: http://devicetree.org/meta-schemas/core.yaml#

title: Simple eMMC hardware reset provider binding

maintainers:

  - Ulf Hansson <ulf.hansson@linaro.org>

description:

  The purpose of this driver is to perform standard eMMC hw reset

  procedure, as described by Jedec 4.4 specification. This procedure is

  performed just after MMC core enabled power to the given mmc host (to

  fix possible issues if bootloader has left eMMC card in initialized or

  unknown state), and before performing complete system reboot (also in

  case of emergency reboot call). The latter is needed on boards, which

  doesn't have hardware reset logic connected to emmc card and (limited or

  broken) ROM bootloaders are unable to read second stage from the emmc

  card if the card is left in unknown or already initialized state.

properties:

  compatible:

    const: mmc-pwrseq-emmc

  reset-gpios:

    minItems: 1

    description:

      contains a GPIO specifier. The reset GPIO is asserted

      and then deasserted to perform eMMC card reset. To perform

      reset procedure as described in Jedec 4.4 specification, the

      gpio line should be defined as GPIO_ACTIVE_LOW.

required:

  - compatible

  - reset-gpios

examples:

  - |

    #include <dt-bindings/gpio/gpio.h>

    sdhci0_pwrseq {

      compatible = "mmc-pwrseq-emmc";

      reset-gpios = <&gpio1 12 GPIO_ACTIVE_LOW>;

    };

...

* Marvell SD8787 power sequence provider

Required properties:

- compatible: must be "mmc-pwrseq-sd8787".

- powerdown-gpios: contains a power down GPIO specifier with the

		   default active state

- reset-gpios: contains a reset GPIO specifier with the default

		   active state

Example:

	wifi_pwrseq: wifi_pwrseq {

		compatible = "mmc-pwrseq-sd8787";

		powerdown-gpios = <&twl_gpio 0 GPIO_ACTIVE_LOW>;

		reset-gpios = <&twl_gpio 1 GPIO_ACTIVE_LOW>;

	}

# SPDX-License-Identifier: GPL-2.0

%YAML 1.2

---

$id: http://devicetree.org/schemas/mmc/mmc-pwrseq-sd8787.yaml#

$schema: http://devicetree.org/meta-schemas/core.yaml#

title: Marvell SD8787 power sequence provider binding

maintainers:

  - Ulf Hansson <ulf.hansson@linaro.org>

properties:

  compatible:

    const: mmc-pwrseq-sd8787

  powerdown-gpios:

    minItems: 1

    description:

      contains a power down GPIO specifier with the default active state

  reset-gpios:

    minItems: 1

    description:

      contains a reset GPIO specifier with the default active state

required:

  - compatible

  - powerdown-gpios

  - reset-gpios

examples:

  - |

    #include <dt-bindings/gpio/gpio.h>

    wifi_pwrseq: wifi_pwrseq {

      compatible = "mmc-pwrseq-sd8787";

      powerdown-gpios = <&twl_gpio 0 GPIO_ACTIVE_LOW>;

      reset-gpios = <&twl_gpio 1 GPIO_ACTIVE_LOW>;

    };

...

* The simple MMC power sequence provider

The purpose of the simple MMC power sequence provider is to supports a set of

common properties between various SOC designs. It thus enables us to use the

same provider for several SOC designs.

Required properties:

- compatible : contains "mmc-pwrseq-simple".

Optional properties:

- reset-gpios : contains a list of GPIO specifiers. The reset GPIOs are asserted

	at initialization and prior we start the power up procedure of the card.

	They will be de-asserted right after the power has been provided to the

	card.

- clocks : Must contain an entry for the entry in clock-names.

  See ../clocks/clock-bindings.txt for details.

- clock-names : Must include the following entry:

  "ext_clock" (External clock provided to the card).

- post-power-on-delay-ms : Delay in ms after powering the card and

	de-asserting the reset-gpios (if any)

- power-off-delay-us : Delay in us after asserting the reset-gpios (if any)

	during power off of the card.

Example:

	sdhci0_pwrseq {

		compatible = "mmc-pwrseq-simple";

		reset-gpios = <&gpio1 12 GPIO_ACTIVE_LOW>;

		clocks = <&clk_32768_ck>;

		clock-names = "ext_clock";

	}