Back in Linux < 3.6 days, the cdc-wdm ports exposed by the QMI driver
were flagged as owned by the 'usb' subsystem. That changed in 3.6 when
the subsystem was renamed to 'usbmisc':
https://mail.gnome.org/archives/networkmanager-list/2012-June/msg00125.html
This patch removes all monitoring of the 'usb' subsystem completely,
which is anyway a valid subsystem but for which we shouldn't need any
special handling. Right now, with newer kernels, we were using that
monitoring exclusively to get notified of full USB device remove
events, which is really not required as we already process the port
removals one by one.
We simplify the logic everywhere that attempted to match either the
'usb' or 'usbmisc' subsystems, and we no longer require the explicit
checks for the port name being named 'cdc-wdm[0-9]*' in the code, as
that is already taken care of by the ID_MM_CANDIDATE udev tag rule.
Implement eUICC change detection for QMI based modems using one of the
following mechanisms (in order of preference):
1. If the modem supports "get slot status" operation, we monitor
physical slot status indications from the modem for the active
slot to detect when ICCID changes.
2. Use "refresh register all" to subscribe refresh indications when
the eUICC triggers REFRESH operation following the enablement of
a new profile.
3. Use "refresh register" to subscribe refresh indications (file
path of EF_ICCID is used) in a similar way. This is used with
older modems that do not support "refresh register all".
If ICCID change is detected, the already existing SIM hot swap
mechanism in MM is triggered.
Some quectel devices, like the EC25 have a non-standard additional '3'
mode value:
0: Disable automatic time zone update via NITZ
1: Enable automatic time zone update via NITZ
3: Enable automatic time zone update via NITZ and update LOCAL time to RTC
If any enabling/disabling command fails, we consider the operation
failed, regardless of the QGPS status. This is because e.g. enabling
involves more operations than just QGPS=1, and so we should treat a
failure in the command sequence as a failure in the whole operation.
The method that reports what location capabilities are supported must
report the capabilities provided by the parent interface plus the
additional capabilities supported by the shared implementation.
Also, simplify the logic a bit reducing the amount of implemented
methods.
Quectel emits "+QUSIM: 1" after eUICC reinitialization. Detect it
and perform SIM swap check if one is encountered.
The motivation here is that M2M eUICC profile switch causes eUICC
reset and this is one way to detect and handle profile switches
properly on Quectel modems. The existing SIM hot swap mechanism is
used as it appears to be suitable for handling profile switches as
well as physical swapping of SIM cards.
