dmanr
mode
The DMA controller supports several modes. The mode values you can set are-
MCA_DMA_MODE_READ when reading from the DMA device.
MCA_DMA_MODE_WRITE to writing to the DMA device.
MCA_DMA_MODE_IO to do DMA to or from an I/O port.
MCA_DMA_MODE_16 to do 16bit transfers.