modem multiplexing mode?

[Dalibor Kranjcic <dalibor.kranjcic@ultra.si>]

Hi,

I have managed to modify serial driver for the Wavecom modem in order to
send AT commands and
PPP traffic separately with use of external fifo:

When traffic comes to the serial driver I check if it is AT or DATA. If
DATA (PPP) traffic comes to serial I proceed it normally, if AT traffic
comes I write it to the external fifo (let's say /dev/ATtraffic).

Sending traffic to serial driver is a little bit tricky. After writing
to fifo I need an entry point to the driver. 
Driver must know that something was written to fifo. So I open an
'dummy' device for example /dev/ttyS12. This allows me to jump into
driver's rs_open method. From there I can read AT commands written to
fifo previously and proceed them to the TX line. Of course this traffic
must be multiplexed before coming to TX lines and I also have to watch
out not to break ppp packets in the middle. 

This works well and I'm really able to send/receive AT packets while ppp
is up, but maybe there is better way to do it?

What do you think about this solution?
Thanks for any advice...


Dalibor.