[U-Boot] SteppingStone

[Cunsuo Guo]

2011/1/26 Matt Johnson <mj1856 at hotmail.com>

> Hello.
>
> I have a custom board with a Samsung s3c2410 (arm920t) processor.  I have
> been unable to get the main branch of u-boot to work with this board.
> However, I have been successful with the old OpenMoko fork.  (I believe it
> is because of the "SteppingStone" microcode. See
> http://wiki.openmoko.org/wiki/S3C2410_Steppingstone if you're unfamiliar.)


> I'd prefer to use the main branch, because the OpenMoko fork is old and
> unmaintained.  The OpenMoko project abandoned u-boot some time ago, in
> favor
> of their "Qi" bootloader.
>
> Has anyone looked at merging the SteppingStone code back in to the main
> branch?  Is there some other workaround that is unclear to me?
>
> Are there other bootloaders that support SteppingStone that I could try?
> I'm looking for something as full-featured as u-boot, but actively
> maintained. The only other that I've found is Vivi - which is super
> ancient.
> Any advice is appreciated.


> Thanks,
> Matt
>
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Steppingstone is just a 4KBytes buffer which works together with some kinda
HW mechanism to copy the first 4KBytes of NAND to it. IMH, you can just
treat it as a feature provided by S3C2410 to support NAND boot. If you have
NOR flash in th board, you can simply boot from NOR flash and ignore this
feature.
I'm not sure whether there is some patches to support this feature or not,
if not, may be you could provide one. The following is my advice to
implement NAND boot for S3C2410:
1. write your NAND device driver, simply read operation is OK;
2. in the relocation part in  Start.S, read code from NAND to RAM use your
NAND device driver, and make sure the relocation part is in the very
beginning 4KBytes range of NAND (by Loader script). In this way, the
first 4KBytes in NAND will be read into Steppingstone buffer and executed,
after execution of relocation code, your bootloader code will be read into
RAM, and then the code can be executed in RAM, the full bootup procedure is
over.