[U-Boot] MIPS: accessing flash > 8MB (Chetan Nanda)

[Chetan Nanda]

On Mon, Jul 27, 2009 at 8:36 PM, Tim Braun <tim.braun at librestream.com>wrote:

> Chetan Nanda wrote:
> > We have a MIPS-4KEC based SoC and running an older version of U-Boot
> > (1.1.3) on it. It is working perfectly fine.
> > Board has 8MB AMD flash and starting address of that flash is
> > 0xBFC00000 (reset vector for MIPS).
> >
> > Problem is that we are not able to access full 8MB of flash. Only
> > 0xBFC00000 - 0xBFFFFFFF (4MB) is accessible, as it lies in un-mapped,
> > un-cached region of MIPS.
> >  From 0xC0000000 lies in mapped memory area of MIPS.
> >
> > Now my questions are, creating entry in TLBs is sufficient to access
> > rest of 4MB of flash?
>
> We are running U-Boot on an Raza Micro / AMD / Alchemy Au1200 and part
> of our board initialization code says :
>
>        /* PCMCIA is on a 36 bit physical address.
>           We need to map it into a 32 bit addresses */
>
>        write_one_tlb(20,                 /* index */
>                      0x01ffe000,         /* Pagemask, 16 MB pages */
>                      CFG_PCMCIA_IO_BASE, /* Hi */
>                      0x3C000017,         /* Lo0 */
>                      0x3C200017);        /* Lo1 */
>
>        write_one_tlb(21,                   /* index */
>                      0x01ffe000,           /* Pagemask, 16 MB pages */
>                      CFG_PCMCIA_ATTR_BASE, /* Hi */
>                      0x3D000017,           /* Lo0 */
>                      0x3D200017);          /* Lo1 */
>
> In our case this maps the PCMCIA interface to usable 32 bit addresses
> just fine, so I'm confident your board
> init code could map your flash to an aliased address that would allow
> access to the whole 8 MB of flash.
>

Thanks for suggestions, I will try these and will back with my findings.


>
>
> Tim Braun
> Sr. Des. Eng.
> Librestream
> O: +1.204.487.0612 ext 203
> F: +1.204.487.0914
> http://www.librestream.com
>
> Now shipping... the Onsight 2000Ex mobile collaboration device, designed
> for hazardous locations that require Class I, Div 2 approval -
> http://www.librestream.com/news_release/2009-01-22.php
>

Thanks,
Chetan Nanda