Accessing MPC862 registers

Accessing MPC862 registers

[Flavio Pereira]

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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RE: Accessing MPC862 registers

[Stephan Linke]

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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Re: Accessing MPC862 registers

[Wolfgang Denk]

In message <742AC4678EF8464697DDDFE3B40F6ECD07E248@SRV-MAILRND.azisa.co.za> you wrote:
>
> 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

I'd appreciate if you'd send me your patches, then.

> 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

You cannot use a stupid "memory dump" command on  the  IMMR  register
space  -  there are reserved entries that may not be accessed at all,
there are registers that must be accessed in the correct length (8  /
16  /  32 bit), etc. You should be able to read individual registers,
though, assuming you know where they are and how to access them (8  /
16 / 32 bit).

> registers which are located from 0xFFF00000 to 0xFFF00DFF from either
> u-boot or the BDI shell?

And once again, this has nothing to do with  linuxppc-embedded.  It's
off topic on this list. Better ask such questions in u-boot-users.

Best regards,

Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
A good aphorism is too hard for the tooth of time, and  is  not  worn
away  by  all  the  centuries,  although  it serves as food for every
epoch.                                  - Friedrich Wilhelm Nietzsche
                          _Miscellaneous Maxims and Opinions_ no. 168

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