[Soekris] SC1100 SIO setup on net4826

[Matt Dainty]

Hi,

My overall aim is to get the LM75A chip working on my net4826 under
OpenBSD.

All of the code to detect and drive the chip is now committed in 4.0,
however I was driving the bus using the gpioiic(4) driver. It was
suggested that the gscsio(4) driver _should_ work using the second ACB
logical device.

gscsio attaches fine, but it never detects any active logical devices.
Putting lots of debug in shows all of the logical devices are set to
power-on defaults as per the SC1100 databook, (although the driver only
supports the two ACB devices).

I've hacked the driver to manually enable and set up the second ACB
which then gets successfully detected, however I also needed to access
the PMR and set the AB2SEL bit so that the ACB is enabled rather than
just working as GPIO (which is how the gpioiic driver was managing to
work).

I suppose my question is, should/is any of this be set up by the BIOS?
I'm a bit unsure regarding the logical device configuration, but setting
the AB2SEL bit seems to be very implementation-specific. This may not be
desirable for all SC1100-based applications if I hardcoded the change,
(into the geodesc(4) driver seems the right spot).

Matt