[U-Boot] [PATCH 3/6] SPL: Port SPL framework to powerpc

[Daniel Schwierzeck]

Hi Stefan,

2012/8/24 Stefan Roese <sr at denx.de>:
> On 08/24/2012 12:56 PM, Stefan Roese wrote:
>> I still would like to move to my suggestion to not copy the header and
>> use the mkimage header values ih_load and ih_ep directly. Right now I
>> don't see any showstopper for doing it this way. I'll send a patch to
>> change this shortly (if everything works out).
>
> Hmmm. As it seems some SPL loading drivers (block like mmc, streaming
> like ymodem) are not that easily converted to skipping the header. So
> I'm not so sure if we should go this way after all...
>
> Comments?
>

I did similar work for my upcoming Lantiq MIPS SoC port. In my
approach I also support compressed u-boot
images as payload (LZO, LZMA). The u-boot image is merged with SPL
image without any padding or
fixed flash offsets to achieve a maximum reduction of flash footprint.

I ended up with doing something like this:

static int spl_parse_image(const image_header_t *hdr, struct spl_image *spl)
{
       u32 magic;

       magic = image_get_magic(hdr);
       if (magic != IH_MAGIC)
               return -1;

       spl->data_addr += image_get_header_size();
       spl->entry_addr = image_get_load(hdr);
       spl->size = image_get_data_size(hdr);
       spl->comp = image_get_comp(hdr);

       if (spl->comp == IH_COMP_NONE)
               spl->load_addr = spl->entry_addr;
       else
               spl->load_addr = CONFIG_LOADADDR;

       return 0;
}

spl->data_addr points to the image header of the payload and is
initialized by the caller
dependent on the used load mechanism. If the payload is uncompressed
it can be directly copied to
its final RAM location. A compressed payload needs an intermediate
copy step if it is stored in SPI or NAND flash.
I chose CONFIG_LOADADDR. After this the decompression function
extracts the image to its final RAM location.

I think we should keep an architecture-neutral SPL image context
inside the generic SPL framework.
The content of this context should be filled by architecture/SoC/board
specific code.

-- 
Best regards,
Daniel