[U-Boot] MII on mpc5200

The u-boot Ethernet support for the mpc5200 turns the device off when not in use. This also has the side effect of also turning off the mii commands like 'mii info' and 'mii dump' which don't work (they always return zeros). I'm poking around the mpc5200 datasheet and I haven't stumbled on to the right bits to reenable mii without also enabling everything else. Can someone familiar with the FEC tell me the right bits to poke?