nanoBSD Driver Build

[Thomas D. Dean]

On 05/28/12 16:24, Thomas D. Dean wrote:
> I need to build a (for me) complicated driver for nanoBSD running on an

In this driver for the Elan SC520, I need to access the mmcr registers.
The cpu manual says these registers start at 0xfffef000.

In a driver, elan_mmcr written by phk at FreeBSD.org, the mmap function
returns i386_btop(0xfffef000).

In my driver, I tried to use

lcd_mmcr = (struct elan_mmcr *)0xfffef000
and
lcd_mmcr = (struct elan_mmcr *)i386_btop(0xfffef000);

accessing lcd_mmcr defined either way causes a trap.

How do I access these registers?

Tom Dean