Date:	Wed, 9 Jun 1999 09:05:51 +0200
From:	Werner Almesberger <almesber@lrc.di.epfl.ch>
To:	Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: 2.3 wish: integrate pcmcia into mainstream kernel

Alan Cox wrote:
> For PCMCIA this partly exists. We have this feature (what DOS calls a point
> enabler I believe) in the Psion5 palmtop port. Werner Almesberger has much
> of this to hand.

I've posted that PCMCIA bit (for 2.3.3) a few weeks ago. It's also on
ftp://lrcftp.epfl.ch/pub/people/almesber/junk/pcmcia.patch.gz

The basic idea is to find PCMCIA/CF IDE disks, which can be readily
handled by the standard IDE driver. No hot-plugging or any of this.

The core part is cis.c, which checks the CIS if it describes a PCMCIA or
CF device the IDE driver knows to handle. There are additional
restrictions, such as only accepting fixed-address configurations (which
is fine on the CL-PS7110/Psion S5/etc., but which may not be ideal on
i386 - don't know how flexible those PCMCIA chips are when it comes to
IO window mapping), and only understanding a single voltage. All this is,
of course, fairly trivial to overcome, if needed.

Setting up the PCMCIA bridge, (*) etc., is left to the system-specific
framework. See drivers/pcmcia/ in
ftp://lrcftp.epfl.ch/pub/people/almesber/psion/crash+burn-22.patch.gz
(for 2.2.1 with various ARM patches) for the full story.

(* I don't think we should assume that the PCMCIA bridge is competely
   operational when Linux runs:
    - Psion S5 case: EPOC (the native OS, run before Linux) enables
      everything we need, _except_ the interrupt. That one is blocked by
      an obscure proprietary chip which I only recently learned to
      program.
    - General case: we'll probably also be able to deal with embedded
      systems where there is no BIOS to enable the PCMCIA/CF.)

There's of course also the work of the MTD people, which I still have to
look at.

- Werner

-- 
  _________________________________________________________________________
 / Werner Almesberger, DI-ICA,EPFL,CH   werner.almesberger@lrc.di.epfl.ch /
/_IN_R_131__Tel_+41_21_693_6621__Fax_+41_21_693_6610_____________________/

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