/dev/openfirm

Hi all.  How do I go about using /dev/openfirm ?  I'm not seeing a lot
of information out there for NetBSD's specific /dev/openfirm.

What I'm trying to do is port some code from Linux that drives the
vacuum fluorescent display/LCD display in an Apple Network Server.

In Open Firmware it's:
(from ofctl)
ff8702d8: /bandit@f2000000/gc@10/lcd@1c000

device_type             6c636400 ........ ........ ........   "lcd"
name                    6c636400 ........ ........ ........   "lcd"
reg                     0001c000 00000020 ........ ........   .......

The linux code that I'm referring to is at:
https://github.com/torvalds/linux/blob/master/drivers/macintosh/ans-lcd.c
https://github.com/torvalds/linux/blob/master/drivers/macintosh/ans-lcd.h

I found some old Linux list archive messages about this:
https://web.archive.org/web/20070904002809/http://www.cyberflunk.com/ans/0655.html

If anyone can point me in the right direction, it would be great.  I'm
hoping I can pass data directly through /dev/openfirm?

Thanks,
Bradley Pearce