tg3: Simplify tx bd assignments

In the following patches, the process the driver will use to assign skb
fragments to transmit BDs will get more complicated.  To prepare for
that new code, this patch seeks to simplify how transmit BDs are
populated.  It does this by separating the code that assigns the BD
members from the logic that controls how the fields are set.
Signed-off-by: NMatt Carlson <mcarlson@broadcom.com>
Reviewed-by: NMichael Chan <mchan@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/tg3.c

@@ -5901,27 +5901,16 @@ static inline int tg3_40bit_overflow_test(struct tg3 *tp, dma_addr_t mapping,
 #endif
 }
 
-static void tg3_set_txd(struct tg3_napi *tnapi, int entry,
-			dma_addr_t mapping, int len, u32 flags,
-			u32 mss_and_is_end)
+static inline void tg3_tx_set_bd(struct tg3_napi *tnapi, u32 entry,
+				 dma_addr_t mapping, u32 len, u32 flags,
+				 u32 mss, u32 vlan)
 {
-	struct tg3_tx_buffer_desc *txd = &tnapi->tx_ring[entry];
-	int is_end = (mss_and_is_end & 0x1);
-	u32 mss = (mss_and_is_end >> 1);
-	u32 vlan_tag = 0;
+	struct tg3_tx_buffer_desc *txbd = &tnapi->tx_ring[entry];
 
-	if (is_end)
-		flags |= TXD_FLAG_END;
-	if (flags & TXD_FLAG_VLAN) {
-		vlan_tag = flags >> 16;
-		flags &= 0xffff;
-	}
-	vlan_tag |= (mss << TXD_MSS_SHIFT);
-
-	txd->addr_hi = ((u64) mapping >> 32);
-	txd->addr_lo = ((u64) mapping & 0xffffffff);
-	txd->len_flags = (len << TXD_LEN_SHIFT) | flags;
-	txd->vlan_tag = vlan_tag << TXD_VLAN_TAG_SHIFT;
+	txbd->addr_hi = ((u64) mapping >> 32);
+	txbd->addr_lo = ((u64) mapping & 0xffffffff);
+	txbd->len_flags = (len << TXD_LEN_SHIFT) | (flags & 0x0000ffff);
+	txbd->vlan_tag = (mss << TXD_MSS_SHIFT) | (vlan << TXD_VLAN_TAG_SHIFT);
 }
 
 static void tg3_skb_error_unmap(struct tg3_napi *tnapi,
@@ -5950,7 +5939,7 @@ static void tg3_skb_error_unmap(struct tg3_napi *tnapi,
 /* Workaround 4GB and 40-bit hardware DMA bugs. */
 static int tigon3_dma_hwbug_workaround(struct tg3_napi *tnapi,
 				       struct sk_buff *skb,
-				       u32 base_flags, u32 mss)
+				       u32 base_flags, u32 mss, u32 vlan)
 {
 	struct tg3 *tp = tnapi->tp;
 	struct sk_buff *new_skb;
@@ -5988,12 +5977,14 @@ static int tigon3_dma_hwbug_workaround(struct tg3_napi *tnapi,
 			ret = -1;
 			dev_kfree_skb(new_skb);
 		} else {
+			base_flags |= TXD_FLAG_END;
+
 			tnapi->tx_buffers[entry].skb = new_skb;
 			dma_unmap_addr_set(&tnapi->tx_buffers[entry],
 					   mapping, new_addr);
 
-			tg3_set_txd(tnapi, entry, new_addr, new_skb->len,
-				    base_flags, 1 | (mss << 1));
+			tg3_tx_set_bd(tnapi, entry, new_addr, new_skb->len,
+				      base_flags, mss, vlan);
 		}
 	}
 
@@ -6051,7 +6042,7 @@ static int tg3_tso_bug(struct tg3 *tp, struct sk_buff *skb)
 static netdev_tx_t tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	struct tg3 *tp = netdev_priv(dev);
-	u32 len, entry, base_flags, mss;
+	u32 len, entry, base_flags, mss, vlan = 0;
 	int i = -1, would_hit_hwbug;
 	dma_addr_t mapping;
 	struct tg3_napi *tnapi;
@@ -6153,9 +6144,12 @@ static netdev_tx_t tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
 		}
 	}
 
-	if (vlan_tx_tag_present(skb))
-		base_flags |= (TXD_FLAG_VLAN |
-			       (vlan_tx_tag_get(skb) << 16));
+#ifdef BCM_KERNEL_SUPPORTS_8021Q
+	if (vlan_tx_tag_present(skb)) {
+		base_flags |= TXD_FLAG_VLAN;
+		vlan = vlan_tx_tag_get(skb);
+	}
+#endif
 
 	if (tg3_flag(tp, USE_JUMBO_BDFLAG) &&
 	    !mss && skb->len > VLAN_ETH_FRAME_LEN)
@@ -6186,13 +6180,21 @@ static netdev_tx_t tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
 	if (tg3_flag(tp, 5701_DMA_BUG))
 		would_hit_hwbug = 1;
 
-	tg3_set_txd(tnapi, entry, mapping, len, base_flags,
-		    (skb_shinfo(skb)->nr_frags == 0) | (mss << 1));
+	tg3_tx_set_bd(tnapi, entry, mapping, len, base_flags |
+		      ((skb_shinfo(skb)->nr_frags == 0) ? TXD_FLAG_END : 0),
+		      mss, vlan);
 
 	entry = NEXT_TX(entry);
 
 	/* Now loop through additional data fragments, and queue them. */
 	if (skb_shinfo(skb)->nr_frags > 0) {
+		u32 tmp_mss = mss;
+
+		if (!tg3_flag(tp, HW_TSO_1) &&
+		    !tg3_flag(tp, HW_TSO_2) &&
+		    !tg3_flag(tp, HW_TSO_3))
+			tmp_mss = 0;
+
 		last = skb_shinfo(skb)->nr_frags - 1;
 		for (i = 0; i <= last; i++) {
 			skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
@@ -6219,14 +6221,9 @@ static netdev_tx_t tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
 			if (tg3_40bit_overflow_test(tp, mapping, len))
 				would_hit_hwbug = 1;
 
-			if (tg3_flag(tp, HW_TSO_1) ||
-			    tg3_flag(tp, HW_TSO_2) ||
-			    tg3_flag(tp, HW_TSO_3))
-				tg3_set_txd(tnapi, entry, mapping, len,
-					    base_flags, (i == last)|(mss << 1));
-			else
-				tg3_set_txd(tnapi, entry, mapping, len,
-					    base_flags, (i == last));
+			tg3_tx_set_bd(tnapi, entry, mapping, len, base_flags |
+				      ((i == last) ? TXD_FLAG_END : 0),
+				      tmp_mss, vlan);
 
 			entry = NEXT_TX(entry);
 		}
@@ -6238,7 +6235,8 @@ static netdev_tx_t tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
 		/* If the workaround fails due to memory/mapping
 		 * failure, silently drop this packet.
 		 */
-		if (tigon3_dma_hwbug_workaround(tnapi, skb, base_flags, mss))
+		if (tigon3_dma_hwbug_workaround(tnapi, skb, base_flags,
+						mss, vlan))
 			goto out_unlock;
 
 		entry = NEXT_TX(tnapi->tx_prod);
@@ -11370,8 +11368,8 @@ static int tg3_run_loopback(struct tg3 *tp, u32 pktsz, int loopback_mode)
 
 	rx_start_idx = rnapi->hw_status->idx[0].rx_producer;
 
-	tg3_set_txd(tnapi, tnapi->tx_prod, map, tx_len,
-		    base_flags, (mss << 1) | 1);
+	tg3_tx_set_bd(tnapi, tnapi->tx_prod, map, tx_len,
+		      base_flags | TXD_FLAG_END, mss, 0);
 
 	tnapi->tx_prod++;