Re: Multi-function PCI devices

[Michael Reinelt <reinelt@eunet.at>]

Tim Waugh wrote:
> 
> On Sat, Apr 07, 2001 at 03:40:13PM -0400, Jeff Garzik wrote:
> 
> > Who said you have to have a separate driver for every single multi-IO
> > card?  A single driver could support all serial+parallel multi-IO cards,
> > for example.
> 
> Okay, I misunderstood.  I'll take a look at doing this for 2.4.
> 
> First of all, parport_pc will need to export the equivalent of
> register_serial (its equivalent is probably parport_pc_probe_port).
> [It actually already does this (conditionally on parport_cs).]
> 
> drivers/parport/parport_serial.c sound okay, or is a different place
> better?

Heh. These multi-I/O-cards come in a lot of different fashions. Let me
explain the NetMos chips a bit:

My card shows up with lspci like that:

lizard:~ # lspci -s 00:0c -vn
00:0c.0 Class 0780: 9710:9835 (rev 01)
        Subsystem: 1000:0012
        Flags: medium devsel, IRQ 11
        I/O ports at 9400 [size=8]
        I/O ports at 9000 [size=8]
        I/O ports at 8800 [size=8]
        I/O ports at 8400 [size=8]
        I/O ports at 8000 [size=8]
        I/O ports at 7800 [size=16]

as you can see, it's class is PCI_CLASS_COMMUNICATION_OTHER

There are 8 different chips from Netmos, they differ mainly in the
number of serial and parallel ports:

9705  -/1P
9735 2S/1P
9745 2S/-
9805  -/1P
9815  -/2P
9835 2S/1P
9845 2S/-
9855  -/2P

the chip id is the same as the PCI device ID. So there are chips with
only serial or parallel ports, and chips with both of them. A chip
without a parallel port (9845) does not really belong to
parport/parport_serial.c :-) On the other hand, a chip without a serial
port should have nothing to do whith serial.c.

At the moment there is a clean solution: serial.c contains only the
device ids of cards with serial ports, the same for parport_pc.c


to summarize the discussion, there are 3 possible solution. I wanted a
simple _and_ clean solution, this seems impossible. 

The simple solution: Gunters 'multifunction quirks'
clean solution #1: a new module according to Jeffs sample code
clean solution #2: 'invisible PCI bridge' from Linus

For both clean solutions I don't know how autoloading/hotplugging would
be handled. But they look good, especially Linus' one.

The simple solution would be _very_ easy to integrate, would not break
existing configurations, and would not require any design changes.

Suggestion: multifunction quirks for 2.4, one of the clean solutions for
2.5?

bye, Michael

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