Where to define IO ports

We are building a board similar to the Freescale Lite5200 (IceCube) board,
using ELDK 3.0 with Linux 2.4.25.

We have added a peripheral to the LocalPlus bus, and I'm trying to figure
out how to modify the kernel startup code to define a memory address range
and generate the proper chip select signal.

Can someone point me to where that sort of thing is done in the kernel
source?

Ed