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Make port roles more flexible. We have modems that do PPP on interfaces other than the primary interface, and that wasn't possible with the old code. So clean up all that logic and move the port organization code into the core so we can reduce code in the plugins. In the new world order, the plugins say whether the port is a QCDM port, an AT port, or ignored. If it's an AT port the plugins get to tag it as primary, secondary, or PPP, or any combination of the 3. This allows for modems where PPP should really be done on the secondary port (Huawei E220, Sierra devices) so that the primary port stays open for command and status. Modem subclasses no longer get asked to handle port grabbing themselves. Instead, that's now done by the generic classes (MMGenericCdma and MMGenericGsm) and the plugins are notified when a port is grabbed so they can add unsolicited response handlers for it. After all ports are grabbed by the generic classes, they get "organized", which assigns various ports to the roles of PRIMARY, SECONDARY, DATA, and QCDM based on specific rules and hints that the plugin provided (which are expressed as MMAtPortFlags). The plugins then have a chance to perform fixups on the primary port if they choose. The plugin code is responsible for determining the port hints (ie MMAtPortFlags) at probe time, instead of having a combination of the plugin and the modem class do the job. This simplifies things greatly for the plugins at the expense of more complicated logic in the core.
ModemManager. The problem ModemManager tries to solve is to provide a unified high level API for communicating with (mobile broadband) modems. While the basic commands are standardized, the more advanced operations (like signal quality monitoring while connected) varies a lot. Using. ModemManager is a system daemon and is not meant to be used directly from the command line. However, since it provides DBus API, it is possible to use 'dbus-send' command to control it from the terminal. There's an example program (tests/mm-test.py) that demonstrates the basic API usage. Implementation. ModemManager is a DBus system bus activated service (meaning it's started automatically when a request arrives). It is written in C. The devices are queried from udev and automatically updated based on hardware events. There's a GInterface (MMModem) that defines the modem interface and any device specific implementation must implement it. There are two generic MMModem implementations to support the basic operations (one for GSM, one for CDMA,) which are common for all cards. 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 MMModem 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's a fully working plugin in the plugins/ directory for Huawei cards that can be used as an example for writing new plugins. Writing new plugins is highly encouraged! API. The 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!