[U-Boot-Users] Booting MPC8272ADS from flash base

[Alex BASTOS <alebas@televes.com>]

> > >
> > > Index: board/mpc8260ads/config.mk
> > > =================================================================
> > > == RCS file: /newcvs/pq2-linux/u-boot/board/mpc8260ads/config.mk,v
> > > retrieving revision 1.1.1.1
> > > diff -u -r1.1.1.1 config.mk
> > > --- board/mpc8260ads/config.mk	24 Aug 2005 12:16:55 -0000	1.1.1.1
> > > +++ board/mpc8260ads/config.mk	14 Oct 2005 08:36:46 -0000
> > > @@ -29,4 +29,4 @@
> > >  # MPC8260ADS, MPC8266ADS, and PQ2FADS-ZU/VR boards
> > >  #
> > >
> > > -TEXT_BASE = 0xfff00000
> > > +TEXT_BASE = 0xff800000
> >
> > Are you sure you are using u-boot-1.1.3?
> > Patch from Jerry Van Baren already made some changes to this file
> > to allow the use of a different TEXT__BASE for lowboot in MPC8272ADS
> > selecting it from Makefile config target.
> > I have this changes already applied in 1.1.3.
> >
>
> I am using u-boot-1.1.3 from Denx ELDK 3.1.1.  There is lowboot
> support in the top level Makefile - but not for any of the 82xx ADS
> platforms.
>
>
>
>
> > > Index: include/configs/MPC8260ADS.h
> > > =================================================================
> > > == RCS file:
> > > /newcvs/pq2-linux/u-boot/include/configs/MPC8260ADS.h,v retrieving
> > > revision 1.1.1.1 diff -u -r1.1.1.1 MPC8260ADS.h
> > > --- include/configs/MPC8260ADS.h	24 Aug 2005 12:17:01 -0000
> > > 1.1.1.1+++ include/configs/MPC8260ADS.h	14 Oct 2005 08:36:46 -0000
> > > @@ -294,13 +294,8 @@
> > >  #define CFG_GBL_DATA_OFFSET	(CFG_INIT_RAM_END - CFG_GBL_DATA_SIZE)
> > >  #define CFG_INIT_SP_OFFSET	CFG_GBL_DATA_OFFSET
> > >
> > > +#define CFG_HRCW_MASTER 0x0e72b605   /* like BCSR version, but
> > > with CIP=1, BMS=1 */
> >
> >
> > In order lowboot patch from Jerry to work (which has been applied to
> > u-boot source, so I recommned you to use) in MPC8272ADS, ISB must
> > also be ISB=100, not ISB=010 as in BCSR.
> >
>
> I think either are fine, as they result in an internal register space
> that doesn't conflict with the boot code (which is initially mapped by
> the CPU to 0x0...0x01ffffff).  The startup assembly code remaps it
> anyway.
>

ISB=100 is needed when you use the MPC8272ADS_lowboot_config target
which is in the u-boot-1.1.3 branch at CVS. Jerry's patch has been
applied there and you can find many other differences.

When using this, it assumes as the initial IMMR 0xF0000000 (so ISB=100)
as this is the value expected by Linux kernel. When using BCSR, u-boot
has to change it from 0x0F000000 to 0xF0000000. So if we have the control
of HRCW, why don't do things in the simpliest way. :-)

See enclosed Jerry's patch applied 04-November-2004

Best regard,

Alex Bastos
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