[coreboot] Question about Coreboot and some chipsets

[ali hagigat]

Coreboot supports 945 North bridge made by Intel. The data sheet of
this IC mentions some registers while there is no table or some
description about them like:
FSBSNPCTL, FSBPMC4, C0ODT, C1AIT(Channel 1 Adaptive Idle Timer
Control),....many registers...
Where can i find the technical details of these registers? How
Coreboot is using FSBSNPCTL in
src/northbridge/intel/i945/early_init.c?
I wonder if any one can direct me to find the necessary information.