Things to do for the bktr driver, in no special order:

o check for a possibility to replace remaining vtophys()
o clean up whitespace before and after braces ("( " -> "(")
o clean up bt8xx.h
o replace vm_offset_t (still any left?)
o not tested on anything but i386 -- alpha/macppc probably will have
  some issues.
o use NetBSD's own i2c-functions
o look for cause of warning (without consequence, as far as I can
  tell): 
  bktr0: ioctl: tsleep error 35 200001c
o split up contents of bktr directory to better places? (also fix
  bktr2netbsd in that case)
o remove #ifdef'd FreeBSD/OpenBSD code (?)
o replace unsigned long by u_int32_t (and similar for int/short?)