net: lan78xx: Add support for VLAN tag stripping.

The chip supports stripping the VLAN tag and reporting it
in metadata.
Complete the support for this.
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/usb/lan78xx.c

@@ -64,6 +64,7 @@
 #define DEFAULT_RX_CSUM_ENABLE		(true)
 #define DEFAULT_TSO_CSUM_ENABLE		(true)
 #define DEFAULT_VLAN_FILTER_ENABLE	(true)
+#define DEFAULT_VLAN_RX_OFFLOAD		(true)
 #define TX_OVERHEAD			(8)
 #define RXW_PADDING			2
 
@@ -2363,6 +2364,11 @@ static int lan78xx_set_features(struct net_device *netdev,
 		pdata->rfe_ctl &= ~(RFE_CTL_ICMP_COE_ | RFE_CTL_IGMP_COE_);
 	}
 
+	if (features & NETIF_F_HW_VLAN_CTAG_RX)
+		pdata->rfe_ctl |= RFE_CTL_VLAN_STRIP_;
+	else
+		pdata->rfe_ctl &= ~RFE_CTL_VLAN_STRIP_;
+
 	if (features & NETIF_F_HW_VLAN_CTAG_FILTER)
 		pdata->rfe_ctl |= RFE_CTL_VLAN_FILTER_;
 	else
@@ -2976,6 +2982,9 @@ static int lan78xx_bind(struct lan78xx_net *dev, struct usb_interface *intf)
 	if (DEFAULT_TSO_CSUM_ENABLE)
 		dev->net->features |= NETIF_F_TSO | NETIF_F_TSO6 | NETIF_F_SG;
 
+	if (DEFAULT_VLAN_RX_OFFLOAD)
+		dev->net->features |= NETIF_F_HW_VLAN_CTAG_RX;
+
 	if (DEFAULT_VLAN_FILTER_ENABLE)
 		dev->net->features |= NETIF_F_HW_VLAN_CTAG_FILTER;
 
@@ -3052,6 +3061,16 @@ static void lan78xx_rx_csum_offload(struct lan78xx_net *dev,
 	}
 }
 
+static void lan78xx_rx_vlan_offload(struct lan78xx_net *dev,
+				    struct sk_buff *skb,
+				    u32 rx_cmd_a, u32 rx_cmd_b)
+{
+	if ((dev->net->features & NETIF_F_HW_VLAN_CTAG_RX) &&
+	    (rx_cmd_a & RX_CMD_A_FVTG_))
+		__vlan_hwaccel_put_tag(skb, htons(ETH_P_8021Q),
+				       (rx_cmd_b & 0xffff));
+}
+
 static void lan78xx_skb_return(struct lan78xx_net *dev, struct sk_buff *skb)
 {
 	int		status;
@@ -3116,6 +3135,8 @@ static int lan78xx_rx(struct lan78xx_net *dev, struct sk_buff *skb)
 			if (skb->len == size) {
 				lan78xx_rx_csum_offload(dev, skb,
 							rx_cmd_a, rx_cmd_b);
+				lan78xx_rx_vlan_offload(dev, skb,
+							rx_cmd_a, rx_cmd_b);
 
 				skb_trim(skb, skb->len - 4); /* remove fcs */
 				skb->truesize = size + sizeof(struct sk_buff);
@@ -3134,6 +3155,7 @@ static int lan78xx_rx(struct lan78xx_net *dev, struct sk_buff *skb)
 			skb_set_tail_pointer(skb2, size);
 
 			lan78xx_rx_csum_offload(dev, skb2, rx_cmd_a, rx_cmd_b);
+			lan78xx_rx_vlan_offload(dev, skb2, rx_cmd_a, rx_cmd_b);
 
 			skb_trim(skb2, skb2->len - 4); /* remove fcs */
 			skb2->truesize = size + sizeof(struct sk_buff);