Can anyone explain to me what the registers are meant to be on entry
to the various *bus_wm_* assembly functions, or tell me where I can
find out?

The Atomwide/Serial Port Multiple Serial Port Podule does not work with
the driver in 1.3 current. It crashes the system whenever any data is
received on one of the ports. The reason for this crash appears to be that
the podulebus_wm_1 function is not implemented. The internal serial port
works, and the mainbus_wm_1 function is implemented. The NetBSD NS16550
com drivers use bus_space_write_multi_1.

	Andrew