[U-Boot-Users] Booting from NAND flash

[Stefan Roese]

Hi Craig,

On Wednesday 28 November 2007, Craig Millen wrote:
> I am currently trying to use u-boot to boot from NAND flash as opposed
> to NOR flash.
> We have both on our board, but would rather just use NAND and depopulate
> the NOR.
>
> Questions:
> There seems to be only one complete setup that includes a bootloader and
> full support for NAND booting, which is the AMCC/Sequoia board.  Though
> my board is very similar, we are using the PPC440EP and not the
> PPC440EPX, with the latter having internal RAM.
> Has anyone booted u-boot from NAND by using the external RAM?

Yes. You missed other platforms that support NAND booting:

AMCC-Acadia (405EZ) and AMCC-Bamboo (440EP)

And here you go: 440EP is already supported.

> Excerpt from u-boot/cpu/ppc4xx/start.S starting at line 389:
>
> #if defined(CONFIG_NAND_SPL)
>  /*
>   * Enable internal SRAM
>   */

This doesn't seem to be the current source code. In the current version this 
looks like this:

#if defined(CONFIG_NAND_SPL)
#if defined(CONFIG_440EPX) || defined(CONFIG_440GRX)
        /*
         * Enable internal SRAM (only on 440EPx/GRx, 440EP/GR have no OCM)
         */
        lis     r2,0x7fff
        ori     r2,r2,0xffff
        mfdcr   r1,isram0_dpc
        and     r1,r1,r2                /* Disable parity check */
        mtdcr   isram0_dpc,r1
        mfdcr   r1,isram0_pmeg
        and     r1,r1,r2                /* Disable pwr mgmt */
        mtdcr   isram0_pmeg,r1
#endif
#if defined(CONFIG_440EP)
        /*
         * On 440EP with no internal SRAM, we setup SDRAM very early
         * and copy the NAND_SPL to SDRAM and jump to it
         */

So you should really update to the latest U-Boot version and use Bamboo as a 
reference for your NAND booting port.

Just let me know if you have any further questions.

Best regards,
Stefan

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