FreeBSD has a driver for the RocketPort cards. The source code reeks
of Linux; I think it's a Linux driver that RocketPort ported to FreeBSD.

I've got a fair way through hacking the Linux macros and inb/outb to
take extra args for bus-space, but I dont really have enough time to
do it justice.

Anyone else want to take it on? If not, anyone got tips on
porting FreeBSD tty drivers to NetBSD?

(In an ideal world, it should probably be redone from scratch and then
backported to Linux, but ...)