My latest attempt at MCP55 support can be found at http://www-cs-students.stanford.edu/~eswierk/misc/linuxbios-dfi-lp_ut_nf590.... .
So far it's only been tested on the DFI LANParty UT NF590 motherboard, booting Linux 2.6.19.
It obviously needs quite a bit of work, including:
- generalizing the CK804 southbridge code; I've simply changed the PCI IDs and hacked on a few functions
- un-hardcoding various bus and device numbers in irq_tables.c and mptable.c
- reinstating the fallback code that I ripped out in an effort to simplify the build process
--Ed