Since the udev support allows to specify a line discipline number as
part of the modem configuration, use that one and report and error if
it has not been set.
The +XSIM notifies us about missing or removed SIM. Use that for telling
the core if a SIM card is present or not. Besides that all other states
are treated as when a SIM card got inserted.
This supports a simple static multiplexer that is activated with setting
the line discipline 23 on the TTY. It is static, because the DLC numbers
are hardcoded.
This is a first attempt at the Infineon modem support. The support
is limited since it doesn't handle the setup of the multiplexer or
the different SIM states yet.
Marcel Holtmann
Marcel Holtmann