[U-Boot-Users] porting to custom at 91 board

[Z.N. <zoldnap@freemail.hu>]

Hi!
> > As some advised, instead of trying to write a boot loader for a custom
> > AT91 board, I wanted to use the loader.bin and u-boot.bin from ATMEL.
> 
> Even better just use U-Boot and forget about loader.bin ...
ok, that wlll be easy :)

> > My alternate question is, how to port u-boot, so that I can start it in
> > RAM with the above configuration (I've got a small boot loader done in
> > assembly, which is loaded from SPI on startup. So I could store u-boot
> > in the SPI flash, and load it to RAM from there on startup by my small
> > boot loader. how to do this? eg. where to load the u-boot image in RAM?
> > I guess I have to also adjust the SDRAM setup and timings which are
> > differing from the atmel DK.). have anyone ported u-boot to such a
> > configuration?
> 
> Instead of doing all  this  which  is  really  non-trivial  and  also
> ineffficient you could just boot from flash. I've just checked in the
> necessary patches for the AT91RM9200DK and CMC_PU2 boards ...

What do you mean by booting from flash? Since I've got only an SPI flash
connected, U-boot has to be taken apart, since the AT91 internal boot
loader can only load 16KB of code from the flash into the internal
processor SRAM. So what is needed is some code for the SPI flash, which
boots the processor, and reads the rest of u-boot from the SPI flash
into the initialized SDRAM.

Does booting from flash solve the SDRAM initialization problem? (I mean
the SDRAM on my board needs worst case memory timings, and I guess the
atmel DK memory setup code does not use worst case timings..)

Thank you all for your help.

Best regards:Zo