Re: Modem Initialization

[Dan Williams <dcbw redhat com>]

On Fri, 2011-04-15 at 12:37 +0200, Vincenzo Romano wrote:
> 2011/4/14 Dan Williams <dcbw redhat com>:
> > On Thu, 2011-04-14 at 16:20 +0200, Vincenzo Romano wrote:
> >> 2011/4/14 Aleksander Morgado <aleksander lanedo com>:
> >> >
> >> >> >> > Where on earth happens the modem initialization in NetWorkmanager?
> >> >> >> > My interest is for GSM/3G modems as well as for POTS/ISDN modems.
> >> >> >> > I've tried to browse the source code but it's quite difficult.
> >> >> >> >
> >> >> >>
> >> >> >> What I've found so far is that the initialization is done in the modemmanager.
> >> >> >> It looks like it's hardcoded, which looks quite weird to me.
> >> >> >> I do need to make some extra optional initialization: is there any
> >> >> >> hook for such a
> >> >> >> need?
> >> >> >
> >> >> > ModemManager has some generic setup steps, plus 'plugins' for each
> >> >> > modem/vendor known to make things differently. If your modem needs
> >> >> > specific AT commands during initialization, you'll probably need to
> >> >> > develop a new plugin for it.
> >> >> >
> >> >> > Cheers,
> >> >>
> >> >> Among other things, I'd need to harvest the localization information (AT+CREG)
> >> >> from GSM/3G modems. 99.999% of such modems implement it but I don't see
> >> >> how to do it.
> >> >>
> >> >> Any idea?
> >> >
> >> > I believe the generic plugin already harvests location area code and
> >> > cell ID whenever available in the AT+CREG? reply. Although I never tried
> >> > it myself, you can possibly use the GetLocation() method in the
> >> > org.freedesktop.ModemManager.Modem.Location interface (once enabled with
> >> > the Enable() method).
> >> >
> >> > Cheers!
> >>
> >> That sounds great. But also needs that I have to write my own D-Bus
> >> code in order
> >> to enable and retrieve the localization data (lac/ci).
> >
> > Ok, what exactly are you trying to do here?  If you can explain that,
> > then maybe we can say what the best course of action here is.  What
> > specific initialization commands do you need to send?
> >
> > Yes, MM exposes location information via the D-Bus interface, because
> > that's how *all* of MM's interaction with the system works, via D-Bus.
> >
> >> And, finally, for the other things I need to do there's no way at all.
> >
> > Such as?  What kinds of things do you need to do?
> >
> > Dan
> >
> >> I've given a look at the modemmanager code and there seems to be no
> >> hook available
> >> to send AT commands before the connection or after it ended.
> 
> For mobile boradband I need to get some network related infos,
> localization (LAC+CI) among them.
> What I understand is that I need to write a D-BUS client to ask
> the modem manager to gather the infos on my behalf.

That's correct.  There's a python example of this in ModemManager's
test/location.py script that enables location services on the modem and
reports the LAC/CI for you.  That should give you an idea of the D-Bus
interfaces required to get the LAC/CI out.  Note that the SIM PIN must
have been entered, and the modem enabled, before location services can
work, because no modem will register with the network until it's (a) PIN
unlocked and (b) powered up.  Regardless of whether MM is used or not.

> But for POTS and ISDN modem I just need to make some specific
> initialization which apperas to be not possible at all.

ModemManager does not (yet) handle POTS modems and will ignore them.
Nor does MM handle ISDN since ISDN doesn't really look like a modem and
doesn't get configured like one either.  ISDN would probably be handled
by NetworkManager instead.

Dan