Linux 5.13 may introduce WWAN framework

The long-developed WWAN (Wireless wide area network) subsystem framework has been merged into the “net-next” branch of the Linux network subsystem and will be launched in Linux 5.13.

This patch introduces initial support for the WWAN framework. Previously, in view of the complexity and heterogeneity of the existing WWAN hardware and interfaces, there was no strict definition of what a WWAN device is and how to represent it. Therefore, it is usually a collection of multiple devices that perform global WWAN functions (such as netdev, Tty, chardev, etc.). This change adds the concept of WWAN port, which is the logical channel of the modem control protocol to expose the protocol to users through character devices. The WWAN core is responsible for the general part, including character device management, and relies on port-driven operations to receive/submit protocol data.

“WWAN antenna” by Long Zheng is licensed under CC BY-SA 2.0

In addition, the initial “user” of the WWAN framework is Qualcomm’s control driver, which allows modems based on MHI QCOM to expose different modem control protocols/ports through the WWAN framework so that the userspace modem tools or daemons (such as ModemManager ) can control WWAN configuration and status (APN configuration, SMS, vendor selection…). A QCOM-based modem can expose one or more of the following protocols:

AT: Well known AT commands interactive protocol (microcom, minicom…)
– MBIM: Mobile Broadband Interface Model (libmbim, mbimcli)
– QMI: QCOM MSM/Modem Interface (libqmi, qmicli)
– QCDM: QCOM Modem diagnostic interface (libqcdm)
– FIREHOSE: XML-based protocol for Modem firmware management (qmi-firmware-update)