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* 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>;
}
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