/dev/bios for 2.6

Eric W. Biederman ebiederman at lnxi.com
Tue Feb 10 11:51:00 CET 2004

Richard Smith <rsmith at bitworks.com> writes:

> Eric W. Biederman wrote:
> > If you look in jedec_probe.c AM29F040, and AM29LV040B are supported so if
> > it is not it should be just a tiny tweak to jedec probe to get the chip
> > recognized.
> Ah.. jdec_probe ok well that gives me a place to start.  I'll go see if I can
> tweak that to find a AM29F040B.  I would have though that the AM29F040 id would
> have matched.

It might I don't know how you have things configured.

> >> The MTD webpage dosen't have any info and I build and inserted lots of
> >> different mtd
> >>modules but nothing indicated they did anything.
> > Do you have a proper map driver?
> Er... I don't know.  How do I check?

MTD has 3 levels of drivers.

- The map driver (i.e. ich2rom and amd76xrom ) which knows how to find
  the ROM chip on a specific board, or chipset.   
- The probe driver (cfi_probe or jedec_probe) which knows how to detect
  which ROM chip you have.
- The chip driver (cfi_cmdset_0001 cfi_cmdset_002..) which knows how
  to use a specific command set regardless of which device you have.
> I've not found any documentation explaining anything about useing the MTD with
> BIOS type flash chips.  Its all Msystems or CF stuff so I've just been guessing.
> My chip is hanging out just like a normal BIOS chip would at physical address
> 0xfff80000 - 0xffffffff.  The 1Meg extended BIOS space area should be enabled in
> my chipset.  So BIOS chipselects should be generated for 0xfff0ffff up.
> There was an option in the kernel building that asked for a start address and a
> size to which I entered 0xfff80000 and 0x80000.
> Hmmm... come to think about it now I may have entered 0x80000 rather than
> 0xfff80000 as the start address..
> In any case.. given my setup what and where do I config this?

Basically it depends on the map driver you are using.  Some of them
can look at your chipset and figure these things out.  Some are really
generic and you have to hard code things.  I don't know if those
work at all.


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