via-velocity: Re-enable transmit scatter-gather support

The velocity hardware can handle up to 7 memory segments. This can be
turned on and off via ethtool. The support was removed in commit

  83c98a8cd04dd0f848574370594886ba3bf56750

but is re-enabled and cleaned up here. It's off by default.

Signed-off-by: Simon Kagstrom <simon.kagstrom@netinsight.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 53 insertions, 30 deletions

diff --git a/drivers/net/via-velocity.c b/drivers/net/via-velocity.c
index 10c4fb25fb4b..a8009c217bd6 100644
--- a/drivers/net/via-velocity.c
+++ b/drivers/net/via-velocity.c
@@ -9,7 +9,6 @@
  *
  * TODO
  *      rx_copybreak/alignment
- *      Scatter gather
  *      More testing
  *
  * The changes are (c) Copyright 2004, Red Hat Inc. <alan@lxorguk.ukuu.org.uk>
@@ -1643,12 +1642,10 @@ out:
  */
 static int velocity_init_td_ring(struct velocity_info *vptr)
 {
-        dma_addr_t curr;
         int j;
 
         /* Init the TD ring entries */
         for (j = 0; j < vptr->tx.numq; j++) {
-                curr = vptr->tx.pool_dma[j];
 
                 vptr->tx.infos[j] = kcalloc(vptr->options.numtx,
                                             sizeof(struct velocity_td_info),
@@ -1714,21 +1711,27 @@ err_free_dma_rings_0:
  *      Release an transmit buffer. If the buffer was preallocated then
  *      recycle it, if not then unmap the buffer.
  */
-static void velocity_free_tx_buf(struct velocity_info *vptr, struct velocity_td_info *tdinfo)
+static void velocity_free_tx_buf(struct velocity_info *vptr,
+                struct velocity_td_info *tdinfo, struct tx_desc *td)
 {
         struct sk_buff *skb = tdinfo->skb;
-        int i;
-        int pktlen;
 
         /*
          *      Don't unmap the pre-allocated tx_bufs
          */
         if (tdinfo->skb_dma) {
+                int i;
 
-                pktlen = max_t(unsigned int, skb->len, ETH_ZLEN);
                 for (i = 0; i < tdinfo->nskb_dma; i++) {
-                        pci_unmap_single(vptr->pdev, tdinfo->skb_dma[i], pktlen, PCI_DMA_TODEVICE);
-                        tdinfo->skb_dma[i] = 0;
+                        size_t pktlen = max_t(size_t, skb->len, ETH_ZLEN);
+
+                        /* For scatter-gather */
+                        if (skb_shinfo(skb)->nr_frags > 0)
+                                pktlen = max_t(size_t, pktlen,
+                                                td->td_buf[i].size & ~TD_QUEUE);
+
+                        pci_unmap_single(vptr->pdev, tdinfo->skb_dma[i],
+                                        le16_to_cpu(pktlen), PCI_DMA_TODEVICE);
                 }
         }
         dev_kfree_skb_irq(skb);
@@ -1930,7 +1933,7 @@ static int velocity_tx_srv(struct velocity_info *vptr, u32 status)
                                 stats->tx_packets++;
                                 stats->tx_bytes += tdinfo->skb->len;
                         }
-                        velocity_free_tx_buf(vptr, tdinfo);
+                        velocity_free_tx_buf(vptr, tdinfo, td);
                         vptr->tx.used[qnum]--;
                 }
                 vptr->tx.tail[qnum] = idx;
@@ -2529,14 +2532,22 @@ static netdev_tx_t velocity_xmit(struct sk_buff *skb,
         struct velocity_td_info *tdinfo;
         unsigned long flags;
         int pktlen;
-        __le16 len;
-        int index;
+        int index, prev;
+        int i = 0;
 
         if (skb_padto(skb, ETH_ZLEN))
                 goto out;
-        pktlen = max_t(unsigned int, skb->len, ETH_ZLEN);
 
-        len = cpu_to_le16(pktlen);
+        /* The hardware can handle at most 7 memory segments, so merge
+         * the skb if there are more */
+        if (skb_shinfo(skb)->nr_frags > 6 && __skb_linearize(skb)) {
+                kfree_skb(skb);
+                return NETDEV_TX_OK;
+        }
+
+        pktlen = skb_shinfo(skb)->nr_frags == 0 ?
+                        max_t(unsigned int, skb->len, ETH_ZLEN) :
+                                skb_headlen(skb);
 
         spin_lock_irqsave(&vptr->lock, flags);
 
@@ -2553,11 +2564,24 @@ static netdev_tx_t velocity_xmit(struct sk_buff *skb,
          */
         tdinfo->skb = skb;
         tdinfo->skb_dma[0] = pci_map_single(vptr->pdev, skb->data, pktlen, PCI_DMA_TODEVICE);
-        td_ptr->tdesc0.len = len;
+        td_ptr->tdesc0.len = cpu_to_le16(pktlen);
         td_ptr->td_buf[0].pa_low = cpu_to_le32(tdinfo->skb_dma[0]);
         td_ptr->td_buf[0].pa_high = 0;
-        td_ptr->td_buf[0].size = len;
-        tdinfo->nskb_dma = 1;
+        td_ptr->td_buf[0].size = cpu_to_le16(pktlen);
+
+        /* Handle fragments */
+        for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+                skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+
+                tdinfo->skb_dma[i + 1] = pci_map_page(vptr->pdev, frag->page,
+                                frag->page_offset, frag->size,
+                                PCI_DMA_TODEVICE);
+
+                td_ptr->td_buf[i + 1].pa_low = cpu_to_le32(tdinfo->skb_dma[i + 1]);
+                td_ptr->td_buf[i + 1].pa_high = 0;
+                td_ptr->td_buf[i + 1].size = cpu_to_le16(frag->size);
+        }
+        tdinfo->nskb_dma = i + 1;
 
         td_ptr->tdesc1.cmd = TCPLS_NORMAL + (tdinfo->nskb_dma + 1) * 16;
 
@@ -2578,23 +2602,21 @@ static netdev_tx_t velocity_xmit(struct sk_buff *skb,
                         td_ptr->tdesc1.TCR |= (TCR0_UDPCK);
                 td_ptr->tdesc1.TCR |= TCR0_IPCK;
         }
-        {
 
-                int prev = index - 1;
+        prev = index - 1;
+        if (prev < 0)
+                prev = vptr->options.numtx - 1;
+        td_ptr->tdesc0.len |= OWNED_BY_NIC;
+        vptr->tx.used[qnum]++;
+        vptr->tx.curr[qnum] = (index + 1) % vptr->options.numtx;
 
-                if (prev < 0)
-                        prev = vptr->options.numtx - 1;
-                td_ptr->tdesc0.len |= OWNED_BY_NIC;
-                vptr->tx.used[qnum]++;
-                vptr->tx.curr[qnum] = (index + 1) % vptr->options.numtx;
+        if (AVAIL_TD(vptr, qnum) < 1)
+                netif_stop_queue(dev);
 
-                if (AVAIL_TD(vptr, qnum) < 1)
-                        netif_stop_queue(dev);
+        td_ptr = &(vptr->tx.rings[qnum][prev]);
+        td_ptr->td_buf[0].size |= TD_QUEUE;
+        mac_tx_queue_wake(vptr->mac_regs, qnum);
 
-                td_ptr = &(vptr->tx.rings[qnum][prev]);
-                td_ptr->td_buf[0].size |= TD_QUEUE;
-                mac_tx_queue_wake(vptr->mac_regs, qnum);
-        }
         dev->trans_start = jiffies;
         spin_unlock_irqrestore(&vptr->lock, flags);
 out:
@@ -3374,6 +3396,7 @@ static const struct ethtool_ops velocity_ethtool_ops = {
         .set_wol        =       velocity_ethtool_set_wol,
         .get_msglevel   =       velocity_get_msglevel,
         .set_msglevel   =       velocity_set_msglevel,
+        .set_sg         =       ethtool_op_set_sg,
         .get_link       =       velocity_get_link,
         .get_coalesce   =       velocity_get_coalesce,
         .set_coalesce   =       velocity_set_coalesce,