For OpenWRT, download the sd-card image from here:
https://openwrt.org/toh/hwdata/globalscale/globalscale_mochabin
I think all I did was copy onto a USB thumb drive and then execute these commands at the u-boot prompt. I may have had to rename something but I don’t recall.
usb start
ext4load usb 0:1 ${kernel_addr_r} Image
ext4load usb 0:1 ${fdt_addr_r} armada-7040-mochabin.dtb
setenv bootargs $console root=PARTUUID=a1ce8a7c-02 rw rootwait
booti ${kernel_addr_r} – ${fdt_addr_r}
