PCMCIA: Statically linked CF card driver?

PCMCIA: Statically linked CF card driver?

[kus Kusche Klaus]

Environment:
* Embedded system, ARM platform, sa1100 processor
* Current Linux standard (or RT) kernel (2.6.12-something)
* Statically linked kernel, no module infrastructure and no initrd at
all
* Static /dev, no udev or devfs
* "hotplug" or card services not wanted
* sa1100 PCMCIA interface, PC Card / CF adapter
  (e.g. Kingston Model No. CF/ADP)
  (possibly other PC cards like WLAN, too,
  but a CF adapter is the only PC card 
  we really should officially support)

Question:
* Any chance to get the CF card working in that environment?
* Any chance to boot from it?

Wishes and non-wishes:
* It would be nice to be able to replace the CF 
  without rebooting.
* It can be assumed that the PC card CF adapter 
  is present during boot.
* There is no need to support hotplugging of the PC card CF adapter.
  (i.e. the PC card CF adapter could be treated as a static,
  builtin device, with its driver linked into the kernel).

Many thanks in advance for any help!

Klaus Kusche
> Entwicklung Software - Steuerung
> Software Development - Control
> 
> KEBA AG
> A-4041 Linz
> Gewerbepark Urfahr
> Tel +43 / 732 / 7090-3120
> Fax +43 / 732 / 7090-6301
> E-Mail: kus@keba.com
> www.keba.com
> 
> 

Re: PCMCIA: Statically linked CF card driver?

[Dominik Brodowski]

Hi,

- use 2.6.12-mm1, and build all you need into the kernel
- in drivers/pcmcia/ds.c , remove the following block:

                /* also, FUNC_ID matching needs to be activated by userspace
                 * after it has re-checked that there is no possible module
                 * with a prod_id/manf_id/card_id match.
                 */
                if (!dev->allow_func_id_match)
                        return 0;

- it should(tm) work then... though I haven't and can't try it myself.

On Thu, Jun 23, 2005 at 09:39:15AM +0200, kus Kusche Klaus wrote:
> * Any chance to boot from it?

> * It would be nice to be able to replace the CF 
>   without rebooting.

I'm not sure whether these two aspects exclude each other.

	Dominik

Re: PCMCIA: Statically linked CF card driver?

[Russell King]

On Thu, Jun 23, 2005 at 09:39:15AM +0200, kus Kusche Klaus wrote:
> Question:
> * Any chance to get the CF card working in that environment?

It should work anyway, although you'll need to use cardmgr with vanilla
mainline kernels.

> * Any chance to boot from it?

Maybe, maybe not.  Even with Dominik's great work, I suspect that PCMCIA
may suffer the same problem as USB in this respect, and require a delay
before trying to mount the root filesystem.  We'll have to see when folk
start using this.

> Wishes and non-wishes:
> * It would be nice to be able to replace the CF 
>   without rebooting.

That's an interesting one.  Alan Cox may have done some work on IDE to
resolve this, but there seems to be some issue preventing it (and Alan's
other IDE patches) being merged.

> * It can be assumed that the PC card CF adapter 
>   is present during boot.
> * There is no need to support hotplugging of the PC card CF adapter.
>   (i.e. the PC card CF adapter could be treated as a static,
>   builtin device, with its driver linked into the kernel).

The CF adapter is a dumb piece of hardware which just converts the
socket pins from PCMCIA format to CF format.  It's completely
transparent to software.  In fact, software doesn't even know it's
there.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 Serial core

RE: PCMCIA: Statically linked CF card driver?

[kus Kusche Klaus]

> From: Dominik Brodowski [mailto:linux@dominikbrodowski.net] 
> Hi,
> 
> - use 2.6.12-mm1, and build all you need into the kernel
> - in drivers/pcmcia/ds.c , remove the following block:
> 
>                 /* also, FUNC_ID matching needs to be 
> activated by userspace
>                  * after it has re-checked that there is no 
> possible module
>                  * with a prod_id/manf_id/card_id match.
>                  */
>                 if (!dev->allow_func_id_match)
>                         return 0;
> 
> - it should(tm) work then... though I haven't and can't try it myself.

Thanks, I'll try it.

> > * Any chance to boot from it?
> 
> > * It would be nice to be able to replace the CF 
> >   without rebooting.
> 
> I'm not sure whether these two aspects exclude each other.

We don't need them at the same time:

* Usually, the system boots from flash, 
  and the CF is used for data transfer 
  (and hence should be changeable).

* In case of emergency (when the system in flash got messed up), 
  or for the first-time flash,
  it would be nice to be able to boot from CF.
  In that case, the CF will not be removed in flight!

-- 
Klaus Kusche                 (Software Development - Control Systems)
KEBA AG             Gewerbepark Urfahr, A-4041 Linz, Austria (Europe)
Tel: +43 / 732 / 7090-3120                 Fax: +43 / 732 / 7090-6301
E-Mail: kus@keba.com                                WWW: www.keba.com