[U-Boot] u-boot / MX25L12805D

[Stefan Roese <sr@denx.de>]

On Monday 25 August 2008, Warren Blackwell wrote:
> I appreciate any response to the following query...
>
> I am developing a project which utilizes u-boot. I started from an
> Atheros source package which contains a modified u-boot for their AP83
> reference design. This reference design has an SST flash chip
> (SST39VF6401 -
> http://www.sst.com/products.xhtml/parallel_flash/39/x16/SST39VF6401).
> This all works well.

This is a "normal" parallel NOR FLASH chip with an AMD/Spasion-type command 
interface.

> My OEM partner for the project has developed a Prototype A design, which
> (in principle) is based on AP83. However, the flash chip is different.
> This design has an MXIC flash chip (MX25L12805D -
> http://www.macronix.com/QuickPlace/hq/PageLibrary4825744A00264C7F.nsf/h_
> Index/E2C69FC9EFF9292F4825744A0029FE02/?OpenDocument&PartNo=MX25L12805D)

I just downloaded the datasheet. This seems to be a serial FLASH chip. So you 
need a completely different driver for this chip. And the user interface will 
be different, since serial chips (SPI) don't support the normal memory 
commands like "mm/md".

> I am able to boot the board with this u-boot; however I can not access
> the flash chip properly. The chip is not identified or addressed
> properly.
>
> I don't have any starting source that I can find for this particular
> flash chip. I have tried modifying the #defines in flash.c to no avail.
>
> I have also tried using various source files (flash.c/h) which I was
> able to find under our u-boot source tree, as well as 3rd party
> published source code.
>
> At this stage, I'm under the impression that I need to find (or
> develop!) the u-boot flash driver files. Developing this is a bit out my
> league.

I'm afraid, but for this FLASH porting you will need to "develop" some code.

> Does anyone know of u-boot source which works for the above mentioned
> mxic flash chip?

I have no experience with serial NOR FLASH chips, so I can't tell you if this 
specific chip is supported by the U-Boot SPI FLASH driver.

Best regards,
Stefan

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