Accessing the ROCK-5B kernel source code and BSP

Hi… guys
Hope all are doing well

Recently, i bought the Rock-5B series development board
I have installed the pre-complied Debian image image with the board and it’s working pretty well

Now my aim is to have the access of kernel source code for this Debian image, that’s how i’m following the WiKi provided for the same

https://wiki.radxa.com/Rock5/guide/build-kernel-on-5b

I’m following the steps, mentioned there

however, when i apply the command ./build/mk-kernel.sh rk3588-rock-5b to choose the board then it return back the message as “board ‘rk3588-rock-5b’ not supported!”

pl. suggest me from where do i access the pre-build debian image source code

Thanks
Mahendra

Wiki is outdated, use radxa docs: