[U-Boot-Users] uboot newbie - tqm823 and memory conf question

Tom Maenner tmaenner at aehr.com
Mon Feb 17 20:57:34 CET 2003


On Sun, 16 Feb 2003, Wolfgang Denk wrote:

> In message <3E4D97E5.4030708 at aehr.com> you wrote:
> >
> > I have TQM823L-50 modules, which have a 26bit address / 32 bit I/O
> > external bus and I want to hook up external programmable logic, which
> ...
> > If I understand the MPC823 book correctly there already a "canned"
> > memory engine available to "talk" to an SRAM.
> ...
> > - To which CS is that hooked up to?
> That's completely your own choice.
> Well, not completely. The TQM8xxL modules use:
> 	CS0 / CS1 for the 2 flash banks
> 	CS2       for SDRAM
> 	CS3       for the CAN controllers (if fit)
> So depending if you have CAN on your modules or  not  you  can  chose
> form CS4...CS7 or from CS3...CS7.
Well then, how does the CPU "know" about that area?
- Is the Address area on that bus the actual physical range the CPU sees?
- Or, does it get mapped into the CPUs physical space via configuration?
- How does the CPU know, that it is SRAM or something else?

> > - What needs to be done to the boot-loader - ppcboot|u-boot?
> Strictly speaking, nothing. You can set up the memroy controller  for
> this  CS  whenever  you  need  it,  i.  e.  for  example in the Linux
> deriver's init routine. However, if you want  to  access  the  memory
> under  U-Boot,  you  should  at least add appropriate definitions for
> CFG_BR?_PRELIM and CFG_OR?_PRELIM to your board's config file.
OK, I need to setup the mem controller.
(I don't need access during "boot-loader" time)
I will search in the source there.

Is that then still possible to change the mem controller setup when the
kernel is already coming up?? I hope so!
> > I would really appreciate some help there, since I am just supposed to
> > setup the board for our HW guys.
> Good luck.
Yeah, I need that :-)

Thanks for your help

> Best regards,
> Wolfgang Denk
> --
> Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
> Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
> See us @ Embedded World, Nuremberg, Feb 18-20, Hall 12.0 Booth 12-442
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