DMA Mode - AM011

For DMA mode operation, follow these steps.

1. Select the generic mode by writing a 1 to the QSPI.GEN_SEL register bit.
2. Write the command, address, dummies in the generic FIFO using the read request.
3. The generic quad SPI controller sends the command as programmed in the generic FIFO and reads the data into the RXFIFO.
4. The DMA controller issues DMA requests using the AXI master interface and sends the RXFIFO data.