Serial loop back virtual device

[Manuel Jander <manuel.jander@gmail.com>]

Hi there,

hopefuly this message is going to the right people. I wrote a small
virtual serial loop back driver and I have some questions in regard to
that.

First, the driver basically creates a set of serial port device pairs
(/dev/ttySL0, /dev/ttySL1, etc) and if some programs talks to one of
this ports, the counterpart port will receive all data and vice versa.
This is usful for writing a simulator of a hardware device which has a
serial port, without having to connect to real serial ports together
with a null modem cable or something like that. I'm using to develop a
simulator of Webasto W-Bus (ODB-II) car heating device. The driver can
optionally do line echo, required for K-Line emulation.

Now the questions:

- Did I really need to write a driver like this or are there any
trivial tricks to accomplish this somehow else ? Note, that the
software to talk to my simulator is a propietary windows executable
(using wine), thus I can not modify it. And my computer has only one
single serial port (and I would need to buy a second ODB-II hardware
adapter anyway, software is way much cheaper).

- Is this useful to anyone ? I think it is :) and it would be kind of
stupid if anyone requiring this would have to either use 2 hardware
ports or write another driver like this. But maybe I'm wrong, I dont
know.

- Is this driver worth to be part of the Linux mainline tree ?
Probably some adjustment would be required...

source code is available here:
http://micro.homelinux.net/~mjander/serial_loop.zip

It did built on  2.6.28, hopefuly it also does on the current vanilla tree.

Best Regards,
Manuel