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List:       linux-arm-kernel
Subject:    Re: Direct-mapped Compact Flash on ARM9
From:       Russell King - ARM Linux <linux () arm ! linux ! org ! uk>
Date:       2004-07-01 21:21:41
Message-ID: 20040701222141.B8980 () flint ! arm ! linux ! org ! uk
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On Thu, Jul 01, 2004 at 04:01:06PM -0500, James Graves wrote:
> Howdy y'all,
> 
> I've been evaluating Cogent's CSB337 board, based around Atmel's
> AT91RM9200 (ARM 920T core).
> 
> I would like to get the compact flash working.  This board does not use
> any PCMCIA controller like the SA-1111.
> 
> Instead the CF slot is directly hooked up to the memory bus, with chip
> selects, I/O strobes, interrupt, and such.
> 
> As far as I can tell, there is no support for this currently, so I was
> hoping that someone out there would have some code which does this
> already.
> 
> Failing that, I'll be writing my own driver for this.  I'm slightly
> unsure what exactly will be happening here.
> 
> Looking around the kernel, I see a few interesting files:
> 
>     drivers/pcmcia/hd64465_ss.c
>     arch/sh/kernel/cf-enabler.c
> 
> The first one especially seems instructive.  The comments say the
> HD64465 provides a very thin host bridge layer, since I'm dealing with
> basically _no_ host bridge layer.
> 
> If I follow this, is there anything else I need to watch out for?  I'm
> thinking I don't really want/need the hotplug stuff, since the CSB337
> board would crash if you just yanked out the card.
> 
> Any advice (or code) would be appreciated.

Yes.  Please get out of the idea that you can mmap a CF flash card
directly.  It's completely bogus.  You can't.

CF cards provide an IDE interface to the system.  You need to talk
IDE to them, which means they look like a device not memory.

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