Subject: mipsco questions... and timecounters
To: None <>
From: Garrett D'Amore <>
List: port-mipsco
Date: 09/08/2006 19:59:44
I've started looking at mipsco, and it looks like it will be fairly
straight-forward to convert it to timecounters and the generic TODR support.

However, I have a few questions, which maybe someone can help me out with.

First off, the RAMBO timer (TCOUNT/TBREAK).  It would be very, very
convenient if this timer works like the MIPS3 CP0 timer; that is if
TCOUNT is a count up timer, and TBREAK is a compare value.  It will be
_even better_ if this timer works properly with wrapping.  E.g. if I set
a TBREAK < TCOUNT, then then the counter will count til it wraps,
continue counting from zero, and interrupt when TCOUNT==TBREAK.

If those conditions are true, then I can see changing the mipsco code to
more closely emulate what we do in mips3 code, so that TCOUNT is allowed
to run free, and we use that as the counter for timecounters.

If someone can confirm for me that this understanding is correct, and is
willing to undertake testing, then I'm willing to make the code
modifications, which are simple, to make this work.

The next question I have is in regard to the RTC chip.  It looks like
this is probably an mk48xxx part, and could maybe just use the MI code
with an attachment point.  Does this sound like a reasonable
assessment?  Again, I'm willing to make the changes, resulting in more
common code and less duplication, if someone can confirm and test for me.

Garrett D'Amore, Principal Software Engineer
Tadpole Computer / Computing Technologies Division,
General Dynamics C4 Systems
Phone: 951 325-2134  Fax: 951 325-2191