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Diffstat (limited to 'Documentation/devicetree/bindings/mmc/mmc-pwrseq-emmc.txt')
| -rw-r--r-- | Documentation/devicetree/bindings/mmc/mmc-pwrseq-emmc.txt | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/Documentation/devicetree/bindings/mmc/mmc-pwrseq-emmc.txt b/Documentation/devicetree/bindings/mmc/mmc-pwrseq-emmc.txt new file mode 100644 index 000000000..3d965d57e --- /dev/null +++ b/Documentation/devicetree/bindings/mmc/mmc-pwrseq-emmc.txt @@ -0,0 +1,25 @@ +* 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>; + } |