memory mapped video device drivers

[Stefano Concina]

Hello, net !! I have spent many frustrating hours trying to get my
Hercules Graphic Station card to be used in another mode than VGA
on my PC running SCO Xenix 2.3.2, and basically am hitting the problem
that ther is not a single example of a memory mapped video device in the
manual. From the documentation it is obvious how you can get a device-driver
to map physical memory (using mapphys) to kernel space, but it doesn't say
anything about how to map THAT into user space, which is obviously possible
since that is how the VGA portion is accessed.
My problem is that the graphics card has a bunch of registers that are 
outside the standard VGA address range, so I cannot use the VGA drivers.
So here are my questions:
- anybody running the same card on anything else than VGA out there ? 
- how do you map physical memory to user space ? I tried read/writes to 
  /dev/mem, but that's not exactly memory mapping, plus it's unsafe.

My ultimate goal is to port X11R4 or 5 when it comes out, but I will only be
able to do that if I can talk to the damn thing....

Stefano Concina
stefano at sj.ate.slb.com