<http://mail-index.netbsd.org/tech-kern/2010/04/02/msg007941.html>,
divide each machine's bus.h into bus_defs.h (constants & data types)
and bus_funcs.h (macro implementations of bus_space(9) routines and MD
prototypes).
Note that some bus_space(9) routines' implementation will move to .c
files from inline subroutines or macros in .h files.
I've only made the split for machine architectures where there is PCI.
All of the non-PCI-having architectures will require a similar split.
These #include files are not referenced by any (committed) Makefiles or
header files, yet. Changes to Makefiles, to <sys/bus.h>, and to some
more machine-dependent files will dribble in before I throw the switch.
dyoung