RE: Accessing MPC862 registers

Hi Flavio,

on 862 the internal memory mapped registers are not like plane memory. Only several addresses can actualy be accessed. If you try no
access an non existant register address you cause a bus error.
For that reason you have to consult the manual before you access any address in the IMMR area and in most cases a simple dump tries
to access an area that is to large to avoid invalid accesses.

Regards, Stephan

-----Original Message-----
From: owner-linuxppc-embedded@lists.linuxppc.org
[mailto:owner-linuxppc-embedded@lists.linuxppc.org]On Behalf Of Flavio
Pereira
Sent: Mittwoch, 5. Februar 2003 13:48
To: LinuxPPC-Embedded
Subject: Accessing MPC862 registers



Hi all

I'm hoping that someone can help me here. I'm using the TQM8xxL module
with a MPC862 processor on board. With minor changes to the pin
configurations for the ethernet controller I have gotten U-boot and
Linux to work without any issues. However from my BDI2000 shell, with my
IMMR set to 0xFFF00000 (confirmed), I cannot do memory dumps for the
region 0xFFF00000 - 0xFFF02000. From FFF02000 (DP-RAM) the memory
accesses seem fine. The same goes for the u-boot shell. Obviously u-boot
and linux have managed to access these registers, else the system would
not start? How do I go about doing direct memory accesses to the MPC's
registers which are located from 0xFFF00000 to 0xFFF00DFF from either
u-boot or the BDI shell?

Regards
Flavio Pereira

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