| # 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 |
| |
| 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 |
| |
| additionalProperties: false |
| |
| examples: |
| - | |
| #include <dt-bindings/gpio/gpio.h> |
| pwrseq { |
| compatible = "mmc-pwrseq-emmc"; |
| reset-gpios = <&gpio1 12 GPIO_ACTIVE_LOW>; |
| }; |
| ... |
