1# SPDX-License-Identifier: GPL-2.0 2%YAML 1.2 3--- 4$id: http://devicetree.org/schemas/mmc/mmc-pwrseq-emmc.yaml# 5$schema: http://devicetree.org/meta-schemas/core.yaml# 6 7title: Simple eMMC hardware reset provider 8 9maintainers: 10 - Ulf Hansson <ulf.hansson@linaro.org> 11 12description: 13 The purpose of this driver is to perform standard eMMC hw reset 14 procedure, as described by Jedec 4.4 specification. This procedure is 15 performed just after MMC core enabled power to the given mmc host (to 16 fix possible issues if bootloader has left eMMC card in initialized or 17 unknown state), and before performing complete system reboot (also in 18 case of emergency reboot call). The latter is needed on boards, which 19 doesn't have hardware reset logic connected to emmc card and (limited or 20 broken) ROM bootloaders are unable to read second stage from the emmc 21 card if the card is left in unknown or already initialized state. 22 23properties: 24 compatible: 25 const: mmc-pwrseq-emmc 26 27 reset-gpios: 28 minItems: 1 29 description: 30 contains a GPIO specifier. The reset GPIO is asserted 31 and then deasserted to perform eMMC card reset. To perform 32 reset procedure as described in Jedec 4.4 specification, the 33 gpio line should be defined as GPIO_ACTIVE_LOW. 34 35required: 36 - compatible 37 - reset-gpios 38 39additionalProperties: false 40 41examples: 42 - | 43 #include <dt-bindings/gpio/gpio.h> 44 pwrseq { 45 compatible = "mmc-pwrseq-emmc"; 46 reset-gpios = <&gpio1 12 GPIO_ACTIVE_LOW>; 47 }; 48... 49