No, it's not uptodate. But it's probably good enough to learn about basic concepts. For the devices you're talking about, you'll need to learn about device trees (didn't exist in 2001 at all in Linux), power management, etc.
I've been reading up on DTS stuff already, there's some resources out there, but all of the "kernel developer guides" seem to predate that by a fair bit. I suppose I'll have to familiarize myself with U-Boot as well...
U-Boot has a sort of baby device model implementation. :) Simpler and perhaps easier to grok than Linux, but using the identical DT based HW representation Linux uses later on during boot (it may even modify DTB a bit in memory to pass some information to kernel).
OTOH, depending on platform it may mix this device model with some ad-hoc/hardcoded knowledge about the platform and ifdef mess[1], that is otherwise properly described by DT in Linux. So it can be a mixed bag.
