NetBSD on Rock 5B: current status and WIP bootable image

[Johann Rudloff <johann%sinyax.net@localhost>]

Hi,

I'm working on improving hardware support for the RK3588-based Radxa 
Rock 5B and I'd like to share the work in progress and current status.

The SD card image can be found here:
https://sinyax.net/pub/netbsd/NetBSD-HEAD-aarch64-20230519-rock-5b.img.gz

(An SD card is required, as the used U-Boot version does not yet support 
eMMC.)

The source is available here:
https://git.sr.ht/~cypheon/NetBSD

Versions used:
- Based on NetBSD 10.99.4 (rebased on today's trunk)
- Includes U-Boot 2023.04-rc3 (using Collabora's rock5b branch, very 
close to mainline)
- DTS is an amalgamation of Linux mainline + some RADXA BSP stuff

Things that should work:
- booting :)
- serial console (the only way to do the initial log in for now)
- on-board microSD slot
- eMMC
- USB 2.0 (the two black ports)
  (USB is currently the only way to get ethernet connectivity)
- GPIO

Things that don't work (yet):
- HDMI
- anything PCIe (that includes the on-board ethernet port and NVMe)
- RNG
- audio
- RTC
- there lots of log spam left over from debugging
- probably a lot more that I'm not aware of...

Currently I'm working on squeezing some pixels out of the HDMI port, but 
that looks like it's going to take a while.  After that I plan to look 
at getting PCIe to work.

If anyone is able/willing to test the current version, I'm happy for any 
kind of feedback or questions.  I'd also be interested if someone would 
like to assist me with the process of getting (some of) these changes 
merged.

Best regards
Johann