net: fs_enet: Implement NETIF_F_SG feature

Freescale ethernet controllers have the capability to re-assemble fragmented
data into a single ethernet frame. This patch uses this capability and
implements NETIP_F_SG feature into the fs_enet ethernet driver.

On a MPC885, I get 53% performance improvement on a ftp transfer of a 15Mb file:
  * Without the patch : 2,8 Mbps
  * With the patch : 4,3 Mbps

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/freescale/fs_enet/fs_enet-main.c b/drivers/net/ethernet/freescale/fs_enet/fs_enet-main.c
index 9e2bcb8..a176287 100644 (file)
--- a/drivers/net/ethernet/freescale/fs_enet/fs_enet-main.c
+++ b/drivers/net/ethernet/freescale/fs_enet/fs_enet-main.c
@@ -278,14 +278,20 @@ static int fs_enet_tx_napi(struct napi_struct *napi, int budget)
                        fep->stats.collisions++;
 
                /* unmap */
-               dma_unmap_single(fep->dev, CBDR_BUFADDR(bdp),
-                               skb->len, DMA_TO_DEVICE);
+               if (fep->mapped_as_page[dirtyidx])
+                       dma_unmap_page(fep->dev, CBDR_BUFADDR(bdp),
+                                      CBDR_DATLEN(bdp), DMA_TO_DEVICE);
+               else
+                       dma_unmap_single(fep->dev, CBDR_BUFADDR(bdp),
+                                        CBDR_DATLEN(bdp), DMA_TO_DEVICE);
 
                /*
                 * Free the sk buffer associated with this last transmit.
                 */
-               dev_kfree_skb(skb);
-               fep->tx_skbuff[dirtyidx] = NULL;
+               if (skb) {
+                       dev_kfree_skb(skb);
+                       fep->tx_skbuff[dirtyidx] = NULL;
+               }
 
                /*
                 * Update pointer to next buffer descriptor to be transmitted.
@@ -299,7 +305,7 @@ static int fs_enet_tx_napi(struct napi_struct *napi, int budget)
                 * Since we have freed up a buffer, the ring is no longer
                 * full.
                 */
-               if (!fep->tx_free++)
+               if (++fep->tx_free >= MAX_SKB_FRAGS)
                        do_wake = 1;
                has_tx_work = 1;
        }
@@ -509,6 +515,9 @@ static int fs_enet_start_xmit(struct sk_buff *skb, struct net_device *dev)
        cbd_t __iomem *bdp;
        int curidx;
        u16 sc;
+       int nr_frags = skb_shinfo(skb)->nr_frags;
+       skb_frag_t *frag;
+       int len;
 
 #ifdef CONFIG_FS_ENET_MPC5121_FEC
        if (((unsigned long)skb->data) & 0x3) {
@@ -530,7 +539,7 @@ static int fs_enet_start_xmit(struct sk_buff *skb, struct net_device *dev)
         */
        bdp = fep->cur_tx;
 
-       if (!fep->tx_free || (CBDR_SC(bdp) & BD_ENET_TX_READY)) {
+       if (fep->tx_free <= nr_frags || (CBDR_SC(bdp) & BD_ENET_TX_READY)) {
                netif_stop_queue(dev);
                spin_unlock(&fep->tx_lock);
 
@@ -543,35 +552,42 @@ static int fs_enet_start_xmit(struct sk_buff *skb, struct net_device *dev)
        }
 
        curidx = bdp - fep->tx_bd_base;
-       /*
-        * Clear all of the status flags.
-        */
-       CBDC_SC(bdp, BD_ENET_TX_STATS);
-
-       /*
-        * Save skb pointer.
-        */
-       fep->tx_skbuff[curidx] = skb;
-
-       fep->stats.tx_bytes += skb->len;
 
+       len = skb->len;
+       fep->stats.tx_bytes += len;
+       if (nr_frags)
+               len -= skb->data_len;
+       fep->tx_free -= nr_frags + 1;
        /*
         * Push the data cache so the CPM does not get stale memory data.
         */
        CBDW_BUFADDR(bdp, dma_map_single(fep->dev,
-                               skb->data, skb->len, DMA_TO_DEVICE));
-       CBDW_DATLEN(bdp, skb->len);
+                               skb->data, len, DMA_TO_DEVICE));
+       CBDW_DATLEN(bdp, len);
+
+       fep->mapped_as_page[curidx] = 0;
+       frag = skb_shinfo(skb)->frags;
+       while (nr_frags) {
+               CBDC_SC(bdp,
+                       BD_ENET_TX_STATS | BD_ENET_TX_LAST | BD_ENET_TX_TC);
+               CBDS_SC(bdp, BD_ENET_TX_READY);
+
+               if ((CBDR_SC(bdp) & BD_ENET_TX_WRAP) == 0)
+                       bdp++, curidx++;
+               else
+                       bdp = fep->tx_bd_base, curidx = 0;
 
-       /*
-        * If this was the last BD in the ring, start at the beginning again.
-        */
-       if ((CBDR_SC(bdp) & BD_ENET_TX_WRAP) == 0)
-               fep->cur_tx++;
-       else
-               fep->cur_tx = fep->tx_bd_base;
+               len = skb_frag_size(frag);
+               CBDW_BUFADDR(bdp, skb_frag_dma_map(fep->dev, frag, 0, len,
+                                                  DMA_TO_DEVICE));
+               CBDW_DATLEN(bdp, len);
 
-       if (!--fep->tx_free)
-               netif_stop_queue(dev);
+               fep->tx_skbuff[curidx] = NULL;
+               fep->mapped_as_page[curidx] = 1;
+
+               frag++;
+               nr_frags--;
+       }
 
        /* Trigger transmission start */
        sc = BD_ENET_TX_READY | BD_ENET_TX_INTR |
@@ -582,8 +598,22 @@ static int fs_enet_start_xmit(struct sk_buff *skb, struct net_device *dev)
         * yay for hw reuse :) */
        if (skb->len <= 60)
                sc |= BD_ENET_TX_PAD;
+       CBDC_SC(bdp, BD_ENET_TX_STATS);
        CBDS_SC(bdp, sc);
 
+       /* Save skb pointer. */
+       fep->tx_skbuff[curidx] = skb;
+
+       /* If this was the last BD in the ring, start at the beginning again. */
+       if ((CBDR_SC(bdp) & BD_ENET_TX_WRAP) == 0)
+               bdp++;
+       else
+               bdp = fep->tx_bd_base;
+       fep->cur_tx = bdp;
+
+       if (fep->tx_free < MAX_SKB_FRAGS)
+               netif_stop_queue(dev);
+
        skb_tx_timestamp(skb);
 
        (*fep->ops->tx_kickstart)(dev);
@@ -917,7 +947,7 @@ static int fs_enet_probe(struct platform_device *ofdev)
        }
 
        fpi->rx_ring = 32;
-       fpi->tx_ring = 32;
+       fpi->tx_ring = 64;
        fpi->rx_copybreak = 240;
        fpi->napi_weight = 17;
        fpi->phy_node = of_parse_phandle(ofdev->dev.of_node, "phy-handle", 0);
@@ -955,7 +985,8 @@ static int fs_enet_probe(struct platform_device *ofdev)
 
        privsize = sizeof(*fep) +
                   sizeof(struct sk_buff **) *
-                  (fpi->rx_ring + fpi->tx_ring);
+                    (fpi->rx_ring + fpi->tx_ring) +
+                  sizeof(char) * fpi->tx_ring;
 
        ndev = alloc_etherdev(privsize);
        if (!ndev) {
@@ -978,6 +1009,8 @@ static int fs_enet_probe(struct platform_device *ofdev)
 
        fep->rx_skbuff = (struct sk_buff **)&fep[1];
        fep->tx_skbuff = fep->rx_skbuff + fpi->rx_ring;
+       fep->mapped_as_page = (char *)(fep->rx_skbuff + fpi->rx_ring +
+                                      fpi->tx_ring);
 
        spin_lock_init(&fep->lock);
        spin_lock_init(&fep->tx_lock);
@@ -1007,6 +1040,8 @@ static int fs_enet_probe(struct platform_device *ofdev)
 
        netif_carrier_off(ndev);
 
+       ndev->features |= NETIF_F_SG;
+
        ret = register_netdev(ndev);
        if (ret)
                goto out_free_bd;

diff --git a/drivers/net/ethernet/freescale/fs_enet/fs_enet.h b/drivers/net/ethernet/freescale/fs_enet/fs_enet.h
index 3a4b49e..f184d8f 100644 (file)
--- a/drivers/net/ethernet/freescale/fs_enet/fs_enet.h
+++ b/drivers/net/ethernet/freescale/fs_enet/fs_enet.h
@@ -134,6 +134,7 @@ struct fs_enet_private {
        void __iomem *ring_base;
        struct sk_buff **rx_skbuff;
        struct sk_buff **tx_skbuff;
+       char *mapped_as_page;
        cbd_t __iomem *rx_bd_base;      /* Address of Rx and Tx buffers.    */
        cbd_t __iomem *tx_bd_base;
        cbd_t __iomem *dirty_tx;        /* ring entries to be free()ed.     */