mv643xx_eth: enable hardware TX checksumming with vlan tags

Although mv643xx_eth has no hardware support for inserting a vlan
tag by twiddling some bits in the TX descriptor, it does support
hardware TX checksumming on packets where the IP header starts {a
limited set of values other than 14} bytes into the packet.

This patch sets mv643xx_eth's ->vlan_features to NETIF_F_SG |
NETIF_F_IP_CSUM, which prevents the stack from checksumming vlan'ed
packets in software, and if vlan tags are present on a transmitted
packet, notifies the hardware of this fact by toggling the right
bits in the TX descriptor.

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>

1 files changed, 28 insertions, 1 deletions

diff --git a/drivers/net/mv643xx_eth.c b/drivers/net/mv643xx_eth.c
index 01dd3c505d25..88bb1f1e8065 100644
--- a/drivers/net/mv643xx_eth.c
+++ b/drivers/net/mv643xx_eth.c
@@ -235,6 +235,8 @@ struct tx_desc {
 #define GEN_IP_V4_CHECKSUM              0x00040000
 #define GEN_TCP_UDP_CHECKSUM            0x00020000
 #define UDP_FRAME                       0x00010000
+#define MAC_HDR_EXTRA_4_BYTES           0x00008000
+#define MAC_HDR_EXTRA_8_BYTES           0x00000200
 
 #define TX_IHL_SHIFT                    11
 
@@ -757,12 +759,36 @@ static void txq_submit_skb(struct tx_queue *txq, struct sk_buff *skb)
         desc->buf_ptr = dma_map_single(NULL, skb->data, length, DMA_TO_DEVICE);
 
         if (skb->ip_summed == CHECKSUM_PARTIAL) {
-                BUG_ON(skb->protocol != htons(ETH_P_IP));
+                int mac_hdr_len;
+
+                BUG_ON(skb->protocol != htons(ETH_P_IP) &&
+                       skb->protocol != htons(ETH_P_8021Q));
 
                 cmd_sts |= GEN_TCP_UDP_CHECKSUM |
                            GEN_IP_V4_CHECKSUM   |
                            ip_hdr(skb)->ihl << TX_IHL_SHIFT;
 
+                mac_hdr_len = (void *)ip_hdr(skb) - (void *)skb->data;
+                switch (mac_hdr_len - ETH_HLEN) {
+                case 0:
+                        break;
+                case 4:
+                        cmd_sts |= MAC_HDR_EXTRA_4_BYTES;
+                        break;
+                case 8:
+                        cmd_sts |= MAC_HDR_EXTRA_8_BYTES;
+                        break;
+                case 12:
+                        cmd_sts |= MAC_HDR_EXTRA_4_BYTES;
+                        cmd_sts |= MAC_HDR_EXTRA_8_BYTES;
+                        break;
+                default:
+                        if (net_ratelimit())
+                                dev_printk(KERN_ERR, &txq_to_mp(txq)->dev->dev,
+                                   "mac header length is %d?!\n", mac_hdr_len);
+                        break;
+                }
+
                 switch (ip_hdr(skb)->protocol) {
                 case IPPROTO_UDP:
                         cmd_sts |= UDP_FRAME;
@@ -2565,6 +2591,7 @@ static int mv643xx_eth_probe(struct platform_device *pdev)
          * have to map the buffers to ISA memory which is only 16 MB
          */
         dev->features = NETIF_F_SG | NETIF_F_IP_CSUM;
+        dev->vlan_features = NETIF_F_SG | NETIF_F_IP_CSUM;
 #endif
 
         SET_NETDEV_DEV(dev, &pdev->dev);