Staging
v0.8.1
https://github.com/torvalds/linux
Raw File
Tip revision: 32b88194f71d6ae7768a29f87fbba454728273ee authored by Linus Torvalds on 25 October 2015, 01:39:47 UTC
Linux 4.3-rc7
Tip revision: 32b8819
mmc-pwrseq-emmc.txt
* The simple eMMC hardware reset provider

The purpose of this driver is to perform standard eMMC hw reset
procedure, as descibed 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>;
	}
back to top