Minimum requirements to enable PCMCIA serial card?

[Dominik Brodowski]

Hi,

On Tue, Aug 09, 2005 at 02:45:23PM +0200, Dag Bakke wrote:
> - a 4port serial PCMCIA card and box with a yenta-compatible cardbus 
> bridge.
> - a root fs containing uclibc, busybox and a static /dev.
> - kernel 2.6.13-rc6

> - What is the bare minimum I need to add to my root fs to get access to 
> the 4 serial ports on this card? (Simply booting the kernel is 
> insufficient. I get no indication that the ports are detected.)
> - How difficult would it be to hack serial_cs.c to detect this card 
> directly?

As you need a CIS override for this card, I'd say almost impossible.

> By reading that (and various postings on lkml) I get the impression I 
> need everything + the kitchen sink *and* the icecubemachine:
> udev, libsysfs, sysfsytils, libusb, hotplug, pcmciautils

No. You don't need udev and you don't need libusb. As you need firmware
updates from userspace, you  need:
- libsysfs, which is part of sysfsutils
- the core of hotplug, 
- the hotplug firmware loader[*], and
- pcmciautils


[*] IIRC there is an alternative firmware loading method available in the
kernel. As PCMCIA uses the default functions to call for firmware updates,
this should be used. Then you might not need hotplug at all, if you assert
otherwise that pcmcia.agent gets called somewhen after the PCMCIA card is
inserted. (and, of course, the proper initialization sequence for PCMCIA 
sockets gets called).

You don't need a full-fledged hotplug environment. All you need is to make
sure pcmcia.agent gets called whenever a PCMCIA device is inserted. 

> This gives me an indication that something may want to read 
> "COMpad4.cis", which
> contains:

cp COMpad4.dat (!) COMpad4.cis /lib/firmware/

or wherever your hotplug or non-hotplug firmware handling system wants
firmware to be put at.

> What is the relationship between .cis and .dat?

.dat is so unspecific, that's why pcmciautils names the binary CIS files as 
".cis".

> Which one goes into /lib/firmware/ when using the hotplug mechanism?
> Or is it /lib/firmware/cis/ ?

It's /lib/firmware/, and in it goes the pcmcia-cs ".dat" file renamed to
".cis"

Hope this helps,
	Dominik