Xenomai real-time audio driver for TI PCM3168A codec on the Elk Pi hat.
Have the kernel sources and an ARMv7 cross-compilation toolchain on your host machine, then do:
(https://github.com/elk-audio/elkpi-sdk) available on the host machine, then:
$ export KERNEL_PATH=<path to kernel source tree>
$ export CROSS_COMPILE=<arm compiler prefix>
$ make
It's possible to just use the official Elk Audio OS cross-compiling SDK, in which case you don't have to set the CROSS_COMPILE environment variable since the SDK will do it automatically.
As an alternative, you can build using the devshell option of Bitbake if you have all the Yocto layers ready on the host machine:
$ bitbake -c devshell virtual/kernel
$ export KERNEL_PATH=<path to kernel source in your bitbake tmp build files>
$ make
By default CV gates support is enabled with the definition BCM2835_I2S_CVGATES_SUPPORT.
It is currently set in the Makefile script with this line:
ccflags-y += -DBCM2835_i2S_CVGATES_SUPPORT
Just remove the line if you want to compile without CV gate support.
To load the driver as an out-of-tree module, run as sudo:
$ insmod pcm3168a-elk.ko
$ insmod bcm2835-i2s-elk.ko
$ insmod audio_rtdm.ko audio_buffer_size=<BUFFER SIZE>
If the modules are installed already as part of the Kernel you can just do instead:
$ modprobe audio_rtdm audio_buffer_size=<BUFFER SIZE>
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