Generic interface operation flow:
/* Get xDMA controller */ sc->xdma_tx = xdma_ofw_get(sc->dev, "tx"); /* Allocate virtual channel */ sc->xchan_tx = xdma_channel_alloc(sc->xdma_tx, caps); /* Setup transfer status callback. */ xdma_setup_intr(sc->xchan_tx, my_tx_intr, sc, &sc->ih_tx); /* Request a transfer */ ret = xdma_request(sc->xchan_tx, &req); /* Free the channel */ xdma_channel_free(sc->xdma_tx); /* Free the controller */ xdma_put(sc->xdma_tx);
Less generic (scatter-gather application based on xDMA interface) operation flow:
/* Get xDMA controller */ sc->xdma_tx = xdma_ofw_get(sc->dev, "tx"); /* Allocate virtual channel */ sc->xchan_tx = xdma_channel_alloc(sc->xdma_tx, caps);
int
atse_xdma_tx_intr(void *arg, xdma_transfer_status_t *status)
{
for (;;) {
err = xdma_dequeue_mbuf(sc->xchan_tx, &m, &st);
if (err != 0) {
break;
}
}
}
/* Setup interrupt handler. */
xdma_setup_intr(sc->xchan_tx, atse_xdma_tx_intr, sc, &sc->ih_tx);
/* Prepare SG transfer */
xdma_prep_sg(sc->xchan_tx, TX_QUEUE_SIZE, ...);/* Enqueue (multiple) mbufs to receive */ m = m_getcl(); xdma_enqueue_mbuf(sc->xchan_rx, &m, 0, 4, 4, XDMA_DEV_TO_MEM); m = m_getcl(); xdma_enqueue_mbuf(sc->xchan_rx, &m, 0, 4, 4, XDMA_DEV_TO_MEM); ... xdma_queue_submit(sc->xchan_rx);
/* Enqueue mbuf to transmit */ xdma_enqueue_mbuf(sc->xchan_tx, &m, 0, 4, 4, XDMA_MEM_TO_DEV); xdma_queue_submit(sc->xchan_tx);
DMA engine driver interface. These functions have to be implemented in DMA engine driver
/* Allocate real hardware channel */
int
msgdma_channel_alloc(device_t dev, struct xdma_channel *xchan)
{
}
/* Request a transfer */
static int
pdma_channel_request(device_t dev, struct xdma_channel *xchan, struct xdma_request *req)
{
}
/* Free the channel */
static int
msgdma_channel_free(device_t dev, struct xdma_channel *xchan)
{
}
/* Start/stop DMA operation */
static int
msgdma_channel_control(device_t dev, xdma_channel_t *xchan, int cmd)
{
}Scatter-gather DMA engine driver interface. These functions have to be implemented in DMA engine driver
/* Prepare a channel for SG transfer */
softdma_channel_prep_sg(device_t dev, struct xdma_channel *xchan)
{
...
}
/* Submit sg list */
softdma_channel_submit_sg(device_t dev, struct xdma_channel *xchan,
struct xdma_sglist *sg, uint32_t sg_n)
{
...
}
/* Provide the amount of free entries for requests. */
softdma_channel_capacity(device_t dev, xdma_channel_t *xchan,
uint32_t *capacity)
{
...
}