This is based on the generic_at parser, with unnecessary stuff removed.
The G1 routinely screws up CRLFs, so the parser needs to account for
that. This parser ignores leading CRLFs (which is what reference-ril
does as well), as well as trailing LFs (which are sometimes left out).
CRs are used as end-of-message indicators. Since we're not bothering
tracking CRLFs, there's also no need for a GARBAGE state, or MULTILINE
stuff.
G1 plugin is based on generic_at, with a bunch of stuff dropped
and simplified. We use AT+CFUN=1 for powering on rather than having
a configurable init string. We also manually set the default state
during init (the G1 appears to start in mode V0 by default). The
device (/dev/smd0) is hardcoded.