Yeah, sorry, assumed it was common knowledge. For those out of the loop - a BSP usually consists of a frankensteined mess: a bootloader (often u-boot but sometimes something homebrew), a Linux kernel with a ton of proprietary modules and device-specific hacks to work around HW quirks, basic userspace utilities (often buildroot), some bastardized build tooling building all of that, some solution for firmware upgrades and distribution, and demo programs to prove the hardware actually works.

Most of the BSP is GPL'd software where the final product manufacturer should provide the sources to the general public, but all too often that obligation gets sharted upon, in way too many cases you have to be happy if there are at least credits provided in the user manual or some OSD menu.