BSP with all sources code?

Hello!

Where can I find the full (GPL compliant) sources of the BSP? The BSP linked in the docs (GitHub - BPI-SINOVOIP/BPI-RV2-SF21H8898-OPENWRT-BSP) seems to be very incomplete. It misses at least the sources for the bootloader nor does it build openwrt-siflower-sf21h8 898-bpi-rv2-nand-squashfs-fullflash.img.

Thanks, //richard