[coreboot] Hello and a question.

Myles Watson mylesgw at gmail.com
Wed Aug 11 20:51:23 CEST 2010

On Wed, Aug 11, 2010 at 12:15 PM, Votier, Sean (DS-1)
<SVotier at drs-ds.com> wrote:
> I’ve been on and off the list for a few months. My email system doesn’t seem
> to like list traffic so it’s a bit touch and go so I will have to see how
> long it lasts. It’s been interesting reading but now I have a question….
> I’m writing some BIOS code for the I7520 chipset.  In general, with these
> chipsets is there some basic legacy I/O mapping for parallel, serial and
> other real mode devices by default on power up? I’m hoping that something
> similar happens to the way that the Firmware Hub is made to look like a BIOS
> rom on power up. I need to read one GPIO pin very early in the bios
> initialisation and hope I can just look at a bit at I/O address 378.

I don't have any chipset-specific information, but here are a couple
of thoughts:
- Is there a Super IO chip?  Generally the Super IO chip handles
serial & has some GPIO pins.
- To allow the Super IO to function correctly, the IO there is often
subtractively decoded (if the chipset doesn't claim an address, it
passes it on.)
- I would think that there would be a register in the PCI space for
the chipset that controls the address of the GPIO pins.


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