NiosII DMA Tutorial

Hi aprado,

# include "sys/alt_dma.h"# include "altera_avalon_dma.h"
# define DMA_LENGTH  512
volatile int dma_complete;
short rx_buffer; // pointer to rx buffer
short tx_buffer; // pointer to tx buffer
void dma_done (void* handle, void* data)
{
    int rc;
    // turn the LED off (for DEBUG)
    rc = IORD_ALTERA_AVALON_PIO_DATA(LED_PIO_BASE);
    IOWR_ALTERA_AVALON_PIO_DATA(LED_PIO_BASE, rc & ~0x10);
    
    dma_complete = 1;
}
int test_dma(void)
{
    int rc;
    alt_dma_txchan txchan;
    alt_dma_rxchan rxchan;
    void* tx_data =   (void*) tx_buffer; // pointer to data to send
  
    dma_complete = 0;
    // Create the transmit channel
    if ((txchan = alt_dma_txchan_open("/dev/ts_dma")) == NULL)   {
        printf ("Failed to open transmit channel\n");
        return -1;
        }
    // Create the receive channel
    if ((rxchan = alt_dma_rxchan_open("/dev/ts_dma")) == NULL)   {
        printf ("Failed to open receive channel\n");
        return -2;
        }
    if(alt_dma_txchan_ioctl(txchan, ALT_DMA_SET_MODE_16, NULL)<0)   {
        return -3;
        }
    if(alt_dma_rxchan_ioctl(rxchan,ALT_DMA_SET_MODE_16,NULL)<0)   {
        return -4;
        }
    if(alt_dma_txchan_ioctl(txchan,ALT_DMA_TX_ONLY_OFF,NULL)<0)  {
        return -5;
        }
    if(alt_dma_rxchan_ioctl(rxchan,ALT_DMA_RX_ONLY_OFF,NULL)<0) {
        return -6;
        }
    printf ("Test DMA transfer...\n");
    // turn a LED on (for DEBUG)
    rc = IORD_ALTERA_AVALON_PIO_DATA(LED_PIO_BASE);
    IOWR_ALTERA_AVALON_PIO_DATA(LED_PIO_BASE, rc | 0x10);
    // Post the transmit request
    if ((rc = alt_dma_txchan_send (txchan,tx_data,DMA_LENGTH-16,NULL,NULL)) < 0)    {
        printf ("Failed to post transmit request, reason = %i\n", rc);
        return -7;
        }
    // Post the receive request
    if ((rc = alt_dma_rxchan_prepare (rxchan,rx_buffer,DMA_LENGTH-16, dma_done,NULL)) < 0)   {
        printf ("Failed to post read request, reason = %i\n", rc);
        return -8;
        }
    // wait for transfer to complete
    while (!dma_complete)
        TK_SLEEP(10);
    printf ("Transfer successful!\n");
    
    return 0;
}