Small tool to load firmwares using the Linux sysfs interface.

It's useful when you don't want to use initramfs and kernel modules, but your drivers need to load firmwares.

You need Linux 5.19+ and CONFIG_FW_LOADER_USER_HELPER enabled.

Create directory at /etc/sysfs_fw_loader/ and put json files inside:

[
        {
                "name": "brcmfmac43430-sdio.sudomaker,cle.bin",
                "file": "/lib/firmware/brcm/brcmfmac43430-sdio.bin"
        },
        {
                "name": "brcmfmac43430-sdio.sudomaker,cle.txt",
                "file": "/lib/firmware/brcm/brcmfmac43430-sdio.txt"
        },
        {
                "name": "BCM43430A1.sudomaker,cle.hcd",
                "file": "/lib/firmware/brcm/BCM43430A1.hcd"
        },
        {
                "name": "brcmfmac43430-sdio.sudomaker,cle.clm_blob",
                "file": ""
        },
        {
                "name": "brcmfmac43430-sdio.clm_blob",
                "file": ""
        }
]

The name field is the directory names in /sys/class/firmware/. It's partially matched.

Use an empty file field to indicate you want to instruct the kernel to skip loading this firmware.

You can use the environment variable SYSFS_FW_LOADER_CONFIG_DIR to specify an alternative config directory.

This program will exit when all specified firmware files are loaded. You can use the environment variable SYSFS_FW_LOADER_TIMEOUT to specify a timeout in seconds. It's 10 by default.

• CMake
• C++17 compatible compiler with std::filesystem
• json-c library

mkdir build
cd build
cmake ..
make

Or if you're in a hurry:

g++ -std=c++17 main.cpp -o sysfs_fw_loader -l json-c

AGPLv3