Staging: Octeon Ethernet: Enable scatter-gather.

Octeon ethernet hardware can handle NETIF_F_SG, so we enable it.

A gather list of up to six fragments will fit in the SKB's CB
structure, so no extra memory is required.  If a SKB has more than six
fragments, we must linearize it.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
To: gregkh@suse.de
Patchwork: http://patchwork.linux-mips.org/patch/838/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

2 files changed, 55 insertions, 9 deletions

diff --git a/drivers/staging/octeon/ethernet-tx.c b/drivers/staging/octeon/ethernet-tx.c
index 05b58f8b58fd..bc67e416e421 100644
--- a/drivers/staging/octeon/ethernet-tx.c
+++ b/drivers/staging/octeon/ethernet-tx.c
@@ -53,6 +53,8 @@
 
 #include "cvmx-gmxx-defs.h"
 
+#define CVM_OCT_SKB_CB(skb)     ((u64 *)((skb)->cb))
+
 /*
  * You can define GET_SKBUFF_QOS() to override how the skbuff output
  * function determines which output queue is used. The default
@@ -121,6 +123,7 @@ int cvm_oct_xmit(struct sk_buff *skb, struct net_device *dev)
         uint64_t old_scratch;
         uint64_t old_scratch2;
         int qos;
+        int i;
         enum {QUEUE_CORE, QUEUE_HW, QUEUE_DROP} queue_type;
         struct octeon_ethernet *priv = netdev_priv(dev);
         struct sk_buff *to_free_list;
@@ -171,6 +174,28 @@ int cvm_oct_xmit(struct sk_buff *skb, struct net_device *dev)
         }
 
         /*
+         * We have space for 6 segment pointers, If there will be more
+         * than that, we must linearize.
+         */
+        if (unlikely(skb_shinfo(skb)->nr_frags > 5)) {
+                if (unlikely(__skb_linearize(skb))) {
+                        queue_type = QUEUE_DROP;
+                        if (USE_ASYNC_IOBDMA) {
+                                /* Get the number of skbuffs in use by the hardware */
+                                CVMX_SYNCIOBDMA;
+                                skb_to_free = cvmx_scratch_read64(CVMX_SCR_SCRATCH);
+                        } else {
+                                /* Get the number of skbuffs in use by the hardware */
+                                skb_to_free = cvmx_fau_fetch_and_add32(priv->fau + qos * 4,
+                                                                       MAX_SKB_TO_FREE);
+                        }
+                        skb_to_free = cvm_oct_adjust_skb_to_free(skb_to_free, priv->fau + qos * 4);
+                        spin_lock_irqsave(&priv->tx_free_list[qos].lock, flags);
+                        goto skip_xmit;
+                }
+        }
+
+        /*
          * The CN3XXX series of parts has an errata (GMX-401) which
          * causes the GMX block to hang if a collision occurs towards
          * the end of a <68 byte packet. As a workaround for this, we
@@ -198,13 +223,6 @@ int cvm_oct_xmit(struct sk_buff *skb, struct net_device *dev)
                 }
         }
 
-        /* Build the PKO buffer pointer */
-        hw_buffer.u64 = 0;
-        hw_buffer.s.addr = cvmx_ptr_to_phys(skb->data);
-        hw_buffer.s.pool = 0;
-        hw_buffer.s.size =
-            (unsigned long)skb_end_pointer(skb) - (unsigned long)skb->head;
-
         /* Build the PKO command */
         pko_command.u64 = 0;
         pko_command.s.n2 = 1;   /* Don't pollute L2 with the outgoing packet */
@@ -215,6 +233,31 @@ int cvm_oct_xmit(struct sk_buff *skb, struct net_device *dev)
 
         pko_command.s.dontfree = 1;
         pko_command.s.reg0 = priv->fau + qos * 4;
+
+        /* Build the PKO buffer pointer */
+        hw_buffer.u64 = 0;
+        if (skb_shinfo(skb)->nr_frags == 0) {
+                hw_buffer.s.addr = XKPHYS_TO_PHYS((u64)skb->data);
+                hw_buffer.s.pool = 0;
+                hw_buffer.s.size = skb->len;
+        } else {
+                hw_buffer.s.addr = XKPHYS_TO_PHYS((u64)skb->data);
+                hw_buffer.s.pool = 0;
+                hw_buffer.s.size = skb_headlen(skb);
+                CVM_OCT_SKB_CB(skb)[0] = hw_buffer.u64;
+                for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+                        struct skb_frag_struct *fs = skb_shinfo(skb)->frags + i;
+                        hw_buffer.s.addr = XKPHYS_TO_PHYS((u64)(page_address(fs->page) + fs->page_offset));
+                        hw_buffer.s.size = fs->size;
+                        CVM_OCT_SKB_CB(skb)[i + 1] = hw_buffer.u64;
+                }
+                hw_buffer.s.addr = XKPHYS_TO_PHYS((u64)CVM_OCT_SKB_CB(skb));
+                hw_buffer.s.size = skb_shinfo(skb)->nr_frags + 1;
+                pko_command.s.segs = skb_shinfo(skb)->nr_frags + 1;
+                pko_command.s.gather = 1;
+                goto dont_put_skbuff_in_hw;
+        }
+
         /*
          * See if we can put this skb in the FPA pool. Any strange
          * behavior from the Linux networking stack will most likely
diff --git a/drivers/staging/octeon/ethernet.c b/drivers/staging/octeon/ethernet.c
index 9f5b7419e777..9d632020b9ee 100644
--- a/drivers/staging/octeon/ethernet.c
+++ b/drivers/staging/octeon/ethernet.c
@@ -484,8 +484,11 @@ int cvm_oct_common_init(struct net_device *dev)
             && (always_use_pow || strstr(pow_send_list, dev->name)))
                 priv->queue = -1;
 
-        if (priv->queue != -1 && USE_HW_TCPUDP_CHECKSUM)
-                dev->features |= NETIF_F_IP_CSUM;
+        if (priv->queue != -1) {
+                dev->features |= NETIF_F_SG;
+                if (USE_HW_TCPUDP_CHECKSUM)
+                        dev->features |= NETIF_F_IP_CSUM;
+        }
 
         /* We do our own locking, Linux doesn't need to */
         dev->features |= NETIF_F_LLTX;