Aleksander Morgado
b99757a1f4
Requiring an explicit set of drivers should only be done when we have
different plugins supporting different types of devices of the same
manufacturer based on the drivers in use (e.g. as in the Sierra case).
When the plugin includes a list of required drivers, the plugin filter
will only assume the plugin can be used if at least one of the
available ports is exposed with one of the drivers in the list.
Because of this, if we start probing some ports before all the
expected ports are reported, we may end up not selecting a given
plugin just because the driver match should have been done in a
not-yet-notified port.
E.g. on system boot:
* ttyACM0 is notified.
* min probing time elapses so ttyACM0 probing starts
* Fibocom plugin is not selected for ttyACM0 as no matched
driver ("cdc_acm") is given in the the list of drivers of the
plugin.
* cdc-wdm0 and wwan0 drivers are notified.
* MM creates generic MBIM modem with the Fibocom plugin, but without
XMM features support, because the ttyACM0 port probing was not done
by the Fibocom plugin.
And if we reset the modem after that:
* ttyACM0 is notified.
* cdc-wdm0 and wwan0 drivers are notified.
* min probing time elapses so probing starts for all ports
* Fibocom plugin is selected for all port probings as "cdc_mbim" is
listed in the list of drivers of the plugin.
* MM creates XMM-capable MBIM modem with the Fibocom plugin.
ModemManager
ModemManager provides a unified high level API for communicating with mobile broadband modems, regardless of the protocol used to communicate with the actual device (Generic AT, vendor-specific AT, QCDM, QMI, MBIM...).
Using
ModemManager is a system daemon and is not meant to be used directly from the command line. However, since it provides a DBus API, it is possible to use 'dbus-send' commands or the new 'mmcli' command line interface to control it from the terminal. The devices are queried from udev and automatically updated based on hardware events, although a manual re-scan can also be requested to look for RS232 modems.
Implementation
ModemManager is a DBus system bus activated service (meaning it's started automatically when a request arrives). It is written in C, using glib and gio. Several GInterfaces specify different features that the modems support, including the generic MMIfaceModem3gpp and MMIfaceModemCdma which provide basic operations for 3GPP (GSM, UMTS, LTE) or CDMA (CDMA1x, EV-DO) modems. If a given feature is not available in the modem, the specific interface will not be exported in DBus.
Plugins
Plugins are loaded on startup, and must implement the MMPlugin interface. It consists of a couple of methods which tell the daemon whether the plugin supports a port and to create custom MMBroadbandModem implementations. It most likely makes sense to derive custom modem implementations from one of the generic classes and just add (or override) operations which are not standard. There are multiple fully working plugins in the plugins/ directory that can be used as an example for writing new plugins. Writing new plugins is highly encouraged! The plugin API is open for changes, so if you're writing a plugin and need to add or change some public method, feel free to suggest it!
License
The ModemManager and mmcli binaries are both GPLv2+. The libmm-glib library is LGPLv2+.
Code of Conduct
Please note that this project is released with a Contributor Code of Conduct. By participating in this project you agree to abide by its terms, which you can find in the following link: https://www.freedesktop.org/wiki/CodeOfConduct
CoC issues may be raised to the project maintainers at the following address: modemmanager-devel-owner@lists.freedesktop.org