bank switching

David Woodhouse dwmw2 at
Tue Oct 30 08:57:44 EDT 2007

On Mon, 2007-10-29 at 17:14 +0100, M8 (Servaes Joordens) wrote:
> I use the blackfin embedded uClinux environment. I want to change a 
> flash chip-driver to support all four memory banks which are available. 
> Right now, I have a driver which supports 1 memory bank of 2MB. I want 
> to be able to use the other three memory banks also 2-4Mb, 4-6MB and 6-8MB.
> Memory bank selection is done by using general io pf4 and pf5. For 
> instance: when  pf4 is enabled and pf5 is disabled I am writing in the 
> region 2-4MB.
> What would be the correct way to change the chip driver? Do you have a 
> template or tutorial on bank switching?
> The driver I want to change is: cfi_cmdset_0001.c

No, that's the "chip driver". What you need to provide is a "map driver"
which enables physical access (read/write cycles) to the flash device in

See the MTD_COMPLEX_MAPPINGS config option, which turns simple things
like 'read word' and 'write word' into out-of-line function calls in
your map driver. And see the map drivers which do this already, like


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