Subject: PMU - VIA communication
To: None <port-macppc@netbsd.org>
From: Cherry G. Mathew <cherry.g.mathew@gmail.com>
List: port-macppc
Date: 07/14/2006 02:22:07
Hi,

I was looking at macppc/dev/pm_direct.c

It looks as if the PMU is connected to the VIA by at least the CB1 line.
Also, it looks as if pm_send()/pm_recieve() use the SR register to
bitshift data to/from the PMU. The mode used for this is 0x0c/0x1c
which is via external clocking.
The VIA manual that I'm looking at (  W65C22S Versatile Interface
Adapter (VIA)  DATA SHEET ) tells me that the external clock is hooked
into the VIA on the CB1 register.

That's just fine, until I discovered that the PMU interrupt line is
assumed to be CB1 as well.

This looks odd, because the VIA would be interrupted for every bit
shift during a pm_send()/pm_recieve()

Either I'm looking at the wrong manual, or this is wrong code. I'd
like to know about either possibility.

Thanks for any pointers.

Cherry

-- 
~Cherry