Banking flash

[Nicolas Pitre]

On Thu, 6 Dec 2007, Jon Ringle wrote:

> Nicolas Pitre wrote:
> > On Thu, 6 Dec 2007, Jon Ringle wrote:
> > 
> > > Hi,
> > >
> > > We are in the process of designing a new board around the IXP435.
> The
> > > IXP435 has 4 Expansion bus chip selects with an address space of
> 16MB
> > > per chip select. I can only use CS0 for flash because the other 3
> CSs
> > > are being used for other purposes. The challenge that we have is
> that we
> > > require 32MB of flash storage. One of the options that we are
> > > considering is to use a GPIO pin to bank 16MB of a 32MB Intel Strata
> > > flash chip at any given time to CS0's 16MB address space. I am
> trying to
> > > access the scope of work to be done in Linux to accomplish this and
> I am
> > > asking for feedback on this idea.
> > 
> > You will only need a custom map driver which is pretty trivial to do.
> 
> Just to be sure I looking at the right thing: I could use
> drivers/mtd/maps/ixp4xx.c as a starting point for a custom map, right?

Right, although that particular one looks more complex than average due 
to the various endianness issues, etc.  But that's exactly the proper 
layer where to implement your requirement.


Nicolas