First attempt at implementing the ALSA driver in order to finally get my SoundBlaster X Katana (USB) loudspeaker be handled properly under Linux and to learn how the Linux kernel-space drivers work. This module uses the ALSA and the USB core framework. Because of its educational purpose, there are a lot of comments in the code, which are most most probably not necessary for more experienced driver developers.
Current state of the project: the USB driver is attached to the Katana device successfully. It's able to create an ALSA card structure and associate a volume control structure with it. The driver is not visible in the PulseAudio control panel yet. I guess I need to create a PCM playback structure to see it there. However, the driver is visible in the alsamixer indeed. There is a single volume slider (I don't know what it is exactly) and that slider actually triggers ALSA control callback functions.
NOTICE: The
.vscodeconfiguration can be used in any Linux-kernel-related project but the kernel's version used in paths needs to be adjusted.
make # Build
sudo insmod katana-audio-control.ko # Load module
sudo lsmod | grep katana # Check if loaded
make clean # Clean
sudo rmmod katana_audio_control # Remove module
sudo dmesg # Read logsNOTICE: Sometimes the Linux kernel stubbornly probes the
snd-usb-audiodriver first. Manual removal of this default driver might be helpful (rmmod snd-usb-audio). It will be loaded anyway but most probably after probing of this custom driver. The order of drivers to probe is strange for me.
All logs can be seen using the dmesg command.