smbus statement

SMBUS is disabled by default. Need to manully enable it at FD(function disable register) bit 3(count from 0 to 31). When bit is set to 1, system will disable that device, vice versa.

FD is located at RCBA+3418h in memory.
In PCH spec, FD is defined in D1Fh,F3 (device 1h,function 3)