/**
* gelic_net_xmit - transmits a frame over the device
* @skb: packet to send out
* @netdev: interface device structure
*
* returns 0 on success, <0 on failure
*/
int gelic_net_xmit(struct sk_buff *skb, struct net_device *netdev)
{
struct gelic_card *card = netdev_card(netdev);
struct gelic_descr *descr;
int result;
unsigned long flags;
spin_lock_irqsave(&card->tx_lock, flags);
gelic_card_release_tx_chain(card, 0);
descr = gelic_card_get_next_tx_descr(card);
if (!descr) {
/*
* no more descriptors free
*/
gelic_card_stop_queues(card);
spin_unlock_irqrestore(&card->tx_lock, flags);
return NETDEV_TX_BUSY;
}
result = gelic_descr_prepare_tx(card, descr, skb);
if (result) {
/*
* DMA map failed. As chanses are that failure
* would continue, just release skb and return
*/
netdev->stats.tx_dropped++;
dev_kfree_skb_any(skb);
spin_unlock_irqrestore(&card->tx_lock, flags);
return NETDEV_TX_OK;
}
/*
* link this prepared descriptor to previous one
* to achieve high performance
*/
descr->prev->next_descr_addr = cpu_to_be32(descr->bus_addr);
/*
* as hardware descriptor is modified in the above lines,
* ensure that the hardware sees it
*/
wmb();
if (gelic_card_kick_txdma(card, descr)) {
/*
* kick failed.
* release descriptors which were just prepared
*/
netdev->stats.tx_dropped++;
gelic_descr_release_tx(card, descr);
gelic_descr_release_tx(card, descr->next);
card->tx_chain.tail = descr->next->next;
dev_info(ctodev(card), "%s: kick failure\n", __func__);
} else {
/* OK, DMA started/reserved */
netdev->trans_start = jiffies;
}
spin_unlock_irqrestore(&card->tx_lock, flags);
return NETDEV_TX_OK;
}
/**
* gelic_card_release_tx_chain - processes sent tx descriptors
* @card: adapter structure
* @stop: net_stop sequence
*
* releases the tx descriptors that gelic has finished with
*/
static void gelic_card_release_tx_chain(struct gelic_card *card, int stop)
{
struct gelic_descr_chain *tx_chain;
enum gelic_descr_dma_status status;
struct net_device *netdev;
int release = 0;
for (tx_chain = &card->tx_chain;
tx_chain->head != tx_chain->tail && tx_chain->tail;
tx_chain->tail = tx_chain->tail->next) {
status = gelic_descr_get_status(tx_chain->tail);
netdev = tx_chain->tail->skb->dev;
switch (status) {
case GELIC_DESCR_DMA_RESPONSE_ERROR:
case GELIC_DESCR_DMA_PROTECTION_ERROR:
case GELIC_DESCR_DMA_FORCE_END:
if (printk_ratelimit())
dev_info(ctodev(card),
"%s: forcing end of tx descriptor " \
"with status %x\n",
__func__, status);
netdev->stats.tx_dropped++;
break;
case GELIC_DESCR_DMA_COMPLETE:
if (tx_chain->tail->skb) {
netdev->stats.tx_packets++;
netdev->stats.tx_bytes +=
tx_chain->tail->skb->len;
}
break;
case GELIC_DESCR_DMA_CARDOWNED:
/* pending tx request */
default:
/* any other value (== GELIC_DESCR_DMA_NOT_IN_USE) */
if (!stop)
goto out;
}
gelic_descr_release_tx(card, tx_chain->tail);
release ++;
}
out:
if (!stop && release)
gelic_card_wake_queues(card);
}
