7.1.3. Yocto Recipe: recipes-drivers/msgdma-userio/msgdma-userio.bb
This Yocto recipe enables an out-of-kernel (userspace) build of the msgdma-userio character driver used for transfer data to and from the HPS to the FPGA DDR memory. This driver calls into the DMA_ENGINE API exposed by the altera-msgdma kernel driver. The kernel module altera-msgdma.ko is enabled in recipe-kernel/linux kernel configuration file: recipes-kernel/linux/files/enable-coredla-mod.cfg.
Device tree settings are set to assign base address, IRQ for the altera-msgdma and associated to the msgdma-userio driver. These can be found in recipes-kernel/linux/files/coredla-dts.patch.