net: dsa: add KSZ9893 switch tagging support

KSZ9893 switch is similar to KSZ9477 switch except the ingress tail tag
has 1 byte instead of 2 bytes.  The size of the portmap is smaller and
so the override and lookup bits are also moved.
Signed-off-by: Tristram Ha <Tristram.Ha@microchip.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/dsa.h

@@ -38,6 +38,7 @@ enum dsa_tag_protocol {
 	DSA_TAG_PROTO_EDSA,
 	DSA_TAG_PROTO_GSWIP,
 	DSA_TAG_PROTO_KSZ9477,
+	DSA_TAG_PROTO_KSZ9893,
 	DSA_TAG_PROTO_LAN9303,
 	DSA_TAG_PROTO_MTK,
 	DSA_TAG_PROTO_QCA,

net/dsa/dsa.c

@@ -57,6 +57,7 @@ const struct dsa_device_ops *dsa_device_ops[DSA_TAG_LAST] = {
 #endif
 #ifdef CONFIG_NET_DSA_TAG_KSZ9477
 	[DSA_TAG_PROTO_KSZ9477] = &ksz9477_netdev_ops,
+	[DSA_TAG_PROTO_KSZ9893] = &ksz9893_netdev_ops,
 #endif
 #ifdef CONFIG_NET_DSA_TAG_LAN9303
 	[DSA_TAG_PROTO_LAN9303] = &lan9303_netdev_ops,
@@ -93,6 +94,7 @@ const char *dsa_tag_protocol_to_str(const struct dsa_device_ops *ops)
 #endif
 #ifdef CONFIG_NET_DSA_TAG_KSZ9477
 		[DSA_TAG_PROTO_KSZ9477] = "ksz9477",
+		[DSA_TAG_PROTO_KSZ9893] = "ksz9893",
 #endif
 #ifdef CONFIG_NET_DSA_TAG_LAN9303
 		[DSA_TAG_PROTO_LAN9303] = "lan9303",

net/dsa/dsa_priv.h

@@ -216,6 +216,7 @@ extern const struct dsa_device_ops gswip_netdev_ops;
 
 /* tag_ksz.c */
 extern const struct dsa_device_ops ksz9477_netdev_ops;
+extern const struct dsa_device_ops ksz9893_netdev_ops;
 
 /* tag_lan9303.c */
 extern const struct dsa_device_ops lan9303_netdev_ops;

net/dsa/tag_ksz.c

@@ -16,6 +16,7 @@
 
 /* Typically only one byte is used for tail tag. */
 #define KSZ_EGRESS_TAG_LEN		1
+#define KSZ_INGRESS_TAG_LEN		1
 
 static struct sk_buff *ksz_common_xmit(struct sk_buff *skb,
 				       struct net_device *dev, int len)
@@ -141,3 +142,36 @@ const struct dsa_device_ops ksz9477_netdev_ops = {
 	.rcv	= ksz9477_rcv,
 	.overhead = KSZ9477_INGRESS_TAG_LEN,
 };
+
+#define KSZ9893_TAIL_TAG_OVERRIDE	BIT(5)
+#define KSZ9893_TAIL_TAG_LOOKUP		BIT(6)
+
+static struct sk_buff *ksz9893_xmit(struct sk_buff *skb,
+				    struct net_device *dev)
+{
+	struct dsa_port *dp = dsa_slave_to_port(dev);
+	struct sk_buff *nskb;
+	u8 *addr;
+	u8 *tag;
+
+	nskb = ksz_common_xmit(skb, dev, KSZ_INGRESS_TAG_LEN);
+	if (!nskb)
+		return NULL;
+
+	/* Tag encoding */
+	tag = skb_put(nskb, KSZ_INGRESS_TAG_LEN);
+	addr = skb_mac_header(nskb);
+
+	*tag = BIT(dp->index);
+
+	if (is_link_local_ether_addr(addr))
+		*tag |= KSZ9893_TAIL_TAG_OVERRIDE;
+
+	return nskb;
+}
+
+const struct dsa_device_ops ksz9893_netdev_ops = {
+	.xmit	= ksz9893_xmit,
+	.rcv	= ksz9477_rcv,
+	.overhead = KSZ_INGRESS_TAG_LEN,
+};