[U-Boot-Users] Mixing CFI and non-CFI flashs?

Michael Schwingen
2007-11-02T20:53:26Z

Hi,

I am currently porting u-boot to multiple IXP425-based boards that have
accumulated here over the time. One of them has a slight problem,
because it uses a combination of two flash roms:
- one 8-bit SST 39VF020 boot flash on a 8-bit chip select as boot flash
- one 16-bit Intel 64MBit flash on a 16-bit chip select.

The intel flash is CFI, while the SST flash is not.
I want to use both flash roms, and I want to use as much of the existing
flash code as possible. It seems that when using the CFI code, there is
no easy way to add a non-CFI flash - right?

What would be the best way to use both flash roms? I have come up with:

(1) provide a hook in cfi_flash.c to insert hardcoded values into the
flash_info structure for the non-CFI flash rom. Due to differences
between CFI-AMD and non-CFI AMD flash command cycles, I need to add a
new commandset (eg. CFI_CMDSET_AMD_LEGACY) plus a bit of handler code.

(2) rename all external-visible functions in flash_cfi.c and add wrapper
functions that call either the CFI code or my own code for the non-CFI
flash. This has the disadvantage that I need to duplicate code that is
already present in cfi_flash.c, but is not exported. I have ssen this
done on one chip vendor's u-boot port, and it does not really look nice.

(3) extend the code in cfi_flash.c so that external functions can be
added via function pointers for non-CFI flashs. Same disadvantage as (2).

I have implemented solution (1) now, and it seems to work quite well,
with minimal code needed in the board-setup file, but maybe there are
better ways to do this - comments?

cu
Michael