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Diffstat (limited to 'Documentation/devicetree/bindings/mmc/mmc-pwrseq-emmc.yaml')
-rw-r--r-- | Documentation/devicetree/bindings/mmc/mmc-pwrseq-emmc.yaml | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/mmc/mmc-pwrseq-emmc.yaml b/Documentation/devicetree/bindings/mmc/mmc-pwrseq-emmc.yaml new file mode 100644 index 000000000..1fc7e620f --- /dev/null +++ b/Documentation/devicetree/bindings/mmc/mmc-pwrseq-emmc.yaml @@ -0,0 +1,48 @@ +# 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 + +additionalProperties: false + +examples: + - | + #include <dt-bindings/gpio/gpio.h> + sdhci0_pwrseq { + compatible = "mmc-pwrseq-emmc"; + reset-gpios = <&gpio1 12 GPIO_ACTIVE_LOW>; + }; +... |