Subject: Common Flash Memory Interface

From: [email-masked]
Date: Fri, 22 Apr 2005 13:48:02 +0100

Hi all,

Can anyone out there help?

I'm in the process of designing an Au1100 based board and this question has
both hardware
and software aspects.

I've arranged for a pair of Spansion S29GL256N 256Mbit flash roms to be
connected to the
Au1100 static bus. These devices are each 16bits wide and are connected to
upper and lower
halves of the 32 bit static bus at an address such that the boot code can
reside in them.
After boot, we want to use the remainder of the devices as flash disk using
one of the wear
leveling file systems. Each flash chip implements the Common Flash Memory
Interface standard,
but as they are arranged as 32 bits wide the devices are effectively
interleaved.

Can Linux support this arrangement?
If not, what do other folks do?

I think I could arrange the flash chips as 32M x 16 rather than 16M x 32 and
force the CPU
to boot from 16 bit wide ROM using the ROMSIZE pin on the Au1100. There is
obviously a
significant performance loss in doing this.

Finally, this email is not confidential and is for all Linux-Mips
addressees.

Regards and thanks,

Martin Nichols.

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From: Wolfgang Denk <[email-masked]>
Date: Fri, 22 Apr 2005 17:02:52 +0200

> leveling file systems. Each flash chip implements the Common Flash Memory

OK.

> but as they are arranged as 32 bits wide the devices are effectively

I'd rather say thay are accesses in parallel.

> Can Linux support this arrangement?

Yes, of course. Such a configurationir more or less standard. The MTD
drivers will work just fine.

> Finally, this email is not confidential and is for all Linux-Mips

Then why do you attach such a silly disclaimer?

Best regards,

Wolfgang Denk

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