Table of Content
Documentation about the Hardware
Data Sheet
http://www.goldelico.com/Brochures/DataSheetLetux400.pdf
Schematics
http://projects.goldelico.com/p/letux400/downloads/39/
Networking
Ethernet
Driver might be at drivers/net/phy/realtek.c (perhaps only in 4.x kernels).
Reverse Engineered
Many pieces of information have been collected on the kwaak wiki. Some important entry points are collected below.