440GX + peek/poke utility

440GX + peek/poke utility

[Neil Wilson]

Hi,

I probably just wasn't looking hard enough but would anyone know if a
peek/poke type command line utility would exist for accessing physical
addresses under Linux on a 440GX board ?  Thanks.

Neil

--
Neil Wilson
Airspan Communications Ltd.
Cambridge House, Oxford Road,
Uxbridge, Middx, UB8 1UN, UK.
Tel: +44(0)1895-467265

neilwilson@airspan.com
www.airspan.com

RE: 440GX + peek/poke utility

[Fillod Stephane]

>I probably just wasn't looking hard enough but would anyone know if a
>peek/poke type command line utility would exist for accessing physical
>addresses under Linux on a 440GX board ?  Thanks.

I have such, and I wanted to contribute them to busybox. My peek/poke
even support hotplug (as long as your hardware can do so :-).

On a background note, we used to access physical addresses under U-Boot, =

but the interface was not very confortable, especially for the hardware
guys who type with 2 fingers. They were quite happy when we switched to
Linux (full command line editing, shell scripts under NFS, remote =
operation,
etc.). This is nowadays possible thanks to all the opensource =
hardworkers
who make Linux ported quickly after U-Boot, if not at the same time.
Be they thanked all. REM: one has to know that accessing directly =
physical=20
addresses under an active OS like Linux can add some noise which does =
not
exist under a monitor like U-Boot.

Before contributing, I was wondering what would be a good command line=20
interface. Right now, here it is:

	peek <b|w|l> <addr> [count]
	poke <b|w|l> <addr> <data>

The base of the args is automatically chosen by strtoul().

The memory access is done by this snippet (code is GPL)
 =
http://www.denx.de/twiki/bin/view/PPCEmbedded/DeviceDrivers#Section_Acces=
singPeripheralsFromUserSpace

I haven't contributed the code yet because I'm not satisfied with=20
the syntax. I would prefer setpci syntax, e.g: "3c.l=3D1,2,3" which=20
would translates to "write longword 1 to location at 3c, 2 at 40=20
and 3 at 44", and allow several on the command line.
As you often call several times peek/poke in a shell script, time=20
between I/O can be too significant and fall in side effects compared=20
to a real driver. Thus, ability to gather several writes would be nice.
What do you all think? Do you have other ideas?

Also currently missing:
* 64 bit support (addr on 64bit archs, data type 'q')
* flag to specify little/big endian operation
* poke of more than one value (cf. setpci syntax)
* option to peek/poke binary values (a kind of dd) to stdin/stdout
  so they can be piped with od -x, redirected to a file, etc.
* option to choose the base of values output by peek
* option to set a range with same value/pattern
* option -f to perform the operation on a file instead of /dev/mem
* and maybe syntax sugar to do atomic +1/-1 on a hardware reg,=20
  set_bit/clear_bit (ala linux/include/asm/bitops.h), ..

Wishlist anyone?

I guess it would be nice to have peek/poke working also for PCI devices
(ie. addr relative to PCI ressource base) and PC ISA I/O bus. While the =
PCI=20
access may be addressed by setpci, I don't see much activity with=20
the PC ISA I/O bus, except with parallel port tinkering :)


Best Regards

--=20
Stephane  [... speaking only on my own behalf]

Re: 440GX + peek/poke utility

[Conor McLoughlin]

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Attached is the simple "mempoke" utility I wrote. It can be used on any
linux platform.

-Conor

Neil Wilson wrote:
> Hi,
> 
> I probably just wasn't looking hard enough but would anyone know if a
> peek/poke type command line utility would exist for accessing physical
> addresses under Linux on a 440GX board ?  Thanks.
> 
> Neil
> 
> --
> Neil Wilson
> Airspan Communications Ltd.
> Cambridge House, Oxford Road,
> Uxbridge, Middx, UB8 1UN, UK.
> Tel: +44(0)1895-467265
> 
> neilwilson@airspan.com
> www.airspan.com
> _______________________________________________
> Linuxppc-embedded mailing list
> Linuxppc-embedded@ozlabs.org
> https://ozlabs.org/mailman/listinfo/linuxppc-embedded
> 
> 


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