Re: [ECOS] Flash V2 with 2 flash chips on board !

[Manfred Gruber <m dot gruber at tirol dot com>]

Hi !

thanks a lot for your answer.

Am Sonntag, 20. November 2005 23:14 schrieben Sie:
> Setting up the MMU tables is the responsibility of the platform HAL.
> No other package will know exactly what chips are present on the
> target hardware. The first flash chip can always be mapped to an
> appropriate virtual address. For the second one, you could map it into
> the virtual address space irrespective of whether or not it is
> present. Alternatively you can do run-time detection and only map it
> if present. If the first flash chip is variable size and the second
> must appear contiguous then run-time mapping is unavoidable.

So, as I understand correct,for example I have two flash chips on my device 
2x32MB. The first one is physical on 0xf0000000 and the second one is on 
0x10000000. I have to map them to a virtual address like that:

first chip		virtual 	0xf0000000
					0xf2000000 -- first 32mb
second chip			0xf2000000
					0xf4000000 -- second 32mb

would this be correct ?

the second chip only would be maped if it is present, and my second 
CYG_FLASH_DRIVER() function would so a custom init function to detect if a 
chip is on 0xf2000000?

will this chips then appear as one flash device in redboot? so that later 
linux will detect the redboot partitions, because of concate them in linux ?  

> Once the flash chip(s) have been mapped into the address space you
> need to instantiate device structures for each one. The details of
> this will depend on the family of flash chips you are using. For the
> the AM29xxxxx V2 driver you need two CYG_FLASH_DRIVER() invocations,
> one for each chip. For the first chip you would probably want to use
> the CFI init function, to allow for variable-sized devices.
> Alternatively if the platform HAL has already detected the block
> layout it can fill in the appropriate fields. For the second chip you
> would want a custom init function which checks whether or not the
> platform HAL detected the chip, and then possibly chain to the CFI
> init function to fill in the block details.

OK, thanks now I know my error, I had 2 CYG_FLASH_DRIVER() invocations, which 
both used  CFI init functions and the second chip was not there, so redboot 
does not boot. I will change the second CYG_FLASH_DRIVER() to a custom init 
function and when the chip is is there i will use CFI init.

> One caution: I have had reports that RedBoot still has trouble coping
> with multiple flash chips. I have not investigated further.

i will investigate when i have my hardware with 2 flash chips.

thanks regards manfred 



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