[PATCH] arm: Add extra boot device (UART) to run Ymodem u-boot.img boot on XEA (imx28)

[sbabic at denx.de]

> This commit enables imx28 based XEA board's u-boot.sb (SPL) to download
> u-boot proper (u-boot.img) via Ymodem protocol.
> This is extremely useful in the recovery scenario where u-boot.sb is
> downloaded via uuu utility to SDRAM [*], and then one can upload u-boot
> proper via serial console to fully debrick the device.
> Note - debricking procedure of imx28 devices:
> - NXP's original USB based tools (like mxsldr or uuu) expect single
>   u-boot.sb which is a relic of the old U-Boot (~2013) without SPL and
>   U-Boot proper distinction.
> [*] On Host:
> ------------
> cat << EOF > imx28_xea.lst
> uuu_version 1.3.0
> SDPS: boot -f /srv/tftp/xea/u-boot.sb
> SDPU: done
> EOF
> Please start picocom:
> sudo picocom -b 115200 -s "sz -vv" /dev/ttyUSB1
> sudo ./uuu/uuu -V imx28_xea.lst
> On the U-boot console one shall see:
> Trying to boot from UART
> CCC
> Then please press CTRL+A, S
> and type u-boot.img
> Signed-off-by: Lukasz Majewski <lukma at denx.de>
> Acked-by: Peng Fan <peng.fan at nxp.com>
Applied to u-boot-imx, master, thanks !

Best regards,
Stefano Babic

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