[LinuxBIOS] Setup CAR on Geode GX1 processor

Juergen Beisert juergen127 at kreuzholzen.de
Mon May 28 10:42:38 CEST 2007


Hi Uwe,

On Sunday 27 May 2007 22:59, Uwe Hermann wrote:
> On Sun, May 27, 2007 at 07:19:18PM +0200, Juergen Beisert wrote:
> > Hi,
> >
> > find below my CAR implementation for the Geode GX1 processor. Tested on
> > my Geode GX1 system. Comments are welcome.
>
> Great, thanks!
>
> Is this for v2 or v3 (or both?)

Use it whereever you want. It only depends on the symbols "_sstage0_1" 
and "_car_size". But you can replace them with static values.

I used it in v2, but only to test it, if it works without a working SDRAM 
controller. I was not able to change the buildsystem to use it as a real CAR 
implementation (the v2 build system is to confusing and there are to many 
dependencies I can't control because I do not understand them).

> Can you please post a signed-off patch which puts this file in some
> directory + the surrounding code which is necessary to actually use it?
> I'm really eager to try it out on my ASI 5BLMP (== IGEL WinNET III)...

It was intended for v3, but I can't provide you a patch because I changed the 
way to build it in arch/x86. And Ron don't like this way. So my patch would 
not help.

> > /*
>
> Just a minor thing:
> The usual "This file is part of the LinuxBIOS project." line is missing
> here.

:-) Because it is currently not at part of the LinuxBIOS project.

> >  * Copyright (C) 2007 Juergen Beisert <juergen at kreuzholzen.de>
> >  *
> >  * This program is free software; you can redistribute it and/or modify
> >  * it under the terms of the GNU General Public License as published by
> >  * the Free Software Foundation; either version 2 of the License, or
> >  * (at your option) any later version.
> >
> >
> > 	.globl CacheAsRam
> > CacheAsRam:
>
> Can we make this "cache_as_ram"? We should stick with the coding
> and naming guidelines as much as possible...

Its GPL. Do what you like to do.

> Otherwise the patch is nice and short, but I won't pretend I understand it
> ;) Haven't read the GX1 datasheets, yet...

Its trivial: Read chapter "4.3.2.5 Cache Test Registers"
- switch of cache
- enable write back mode
- fill the cache control data (as it does it by itself when it is enabled)
- use it =8-)

Juergen




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