Firechip Cellular Connectivity - QMI Stack

This repository provides Yocto Project recipes and configurations for enabling cellular connectivity using the Qualcomm MSM Interface (QMI) protocol. It supports various cellular modems from different vendors, offering a modular and extensible architecture.

Overview

This project aims to simplify the integration of cellular modems into embedded Linux systems built with the Yocto Project. It provides a complete software stack, including:

• Core QMI Functionality: A core library for sending and receiving QMI messages.
• QMI Daemon: A daemon process that manages communication with the modem and loads modem-specific plugins.
• Modem-Specific Plugins: Plugins that handle the specific details of communicating with different modem models.
• Kernel Support: Recipes to ensure the necessary kernel modules and configurations are included in the image.
• Udev Rules: Udev rules for dynamic device node creation and management.

Directory Structure

• meta-firechip/: This is the main Yocto layer containing the QMI recipes.
  • conf/: Layer configuration files (e.g., layer.conf).
  • recipes-connectivity/: Contains the recipes for the QMI stack.
    • qmi-core-module/: Recipe for the core QMI library.
    • qmi-daemon/: Recipe for the QMI daemon.
    • qmi-firmware-update-plugin/: Recipe for a generic firmware update plugin.
    • qmi-wwan/: Recipe for kernel modules and network configuration.
    • qualcomm/: Contains recipes for specific Qualcomm-based modems.
      • fibocom/, inforce-computing/, meig/, neoway/, quectel/, sierra-wireless/, simcom/, telit/, u-blox/, variscite/: Subdirectories for different vendors.
        • vendor/model/: Subdirectories for specific modem models within each vendor.
          • 70-*.rules: Udev rules for the modem.
          • *.bbappend: BitBake append files for customizing generic recipes.
          • *-qmi-plugin/: Subdirectories containing modem-specific QMI plugins.
            • *.bbappend: BitBake append files for customizing generic plugin recipes.
            • CMakeLists.txt: CMake build files for the plugin.
            • include/: Header files for the plugin.
            • src/: Source code for the plugin.

Building

To build the QMI stack, you need to integrate the meta-firechip layer into your Yocto build environment. Then, you can build your image using the standard BitBake command:

bitbake <your-image-name>

Make sure that your kernel configuration includes the necessary options for QMI WWAN support (CONFIG_USB_NET_QMI_WWAN).

Key Components and Their Roles

• qmi-core-module: Provides low-level functions for sending and receiving QMI messages. It does not handle QMI message encoding/decoding for specific services.
• qmi-daemon: A user-space daemon that manages communication with the modem. It loads modem-specific plugins and uses the qmi-core-module for QMI communication.
• Modem-Specific Plugins: These plugins handle the details of communicating with specific modem models, including QMI message encoding/decoding, handling specific QMI services, and implementing modem-specific functionalities.
• qmi-wwan: Ensures that the necessary kernel modules are included in the image and configures the network interface.
• Udev Rules: Automatically create consistent device nodes for the modem, regardless of the USB port it's connected to.

Adding Support for a New Modem

To add support for a new modem, you typically need to:

1. Create a new directory under meta-firechip/recipes-connectivity/qualcomm/<vendor>/<model>/.
2. Create udev rules (70-*.rules) for the modem.
3. Create a modem-specific QMI plugin.
4. Create a BitBake recipe for the plugin.
5. If needed, create a .bbappend file to modify a generic recipe.
6. Add any required firmware packages as dependencies.

Dependencies

• Yocto Project
• GLib
• Jansson
• Linux kernel with QMI WWAN support (CONFIG_USB_NET_QMI_WWAN)

Contributing

Contributions are welcome! Please follow the Firechip project's contribution guidelines.

Further Information

• Qualcomm QMI documentation (search online)
• u-blox documentation (if using a u-blox modem)
• Other modem vendor documentation