[PATCH net-next 3/4] net: dsa: Support prepended Broadcom tag

[Florian Fainelli <f.fainelli@gmail.com>]

Add a new type: DSA_TAG_PROTO_PREPEND which allows us to support for the
4-bytes Broadcom tag that we already support, but in a format where it
is pre-pended to the packet instead of located between the MAC SA and
the Ethertyper (DSA_TAG_PROTO_BRCM).

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 include/net/dsa.h  |  1 +
 net/dsa/Kconfig    |  3 +++
 net/dsa/Makefile   |  1 +
 net/dsa/dsa.c      |  3 +++
 net/dsa/dsa_priv.h |  1 +
 net/dsa/tag_brcm.c | 39 ++++++++++++++++++++++++++++++++-------
 6 files changed, 41 insertions(+), 7 deletions(-)

diff --git a/include/net/dsa.h b/include/net/dsa.h
index 68e232fd4b0f..2a05738570d8 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -29,6 +29,7 @@ struct fixed_phy_status;
 enum dsa_tag_protocol {
 	DSA_TAG_PROTO_NONE = 0,
 	DSA_TAG_PROTO_BRCM,
+	DSA_TAG_PROTO_BRCM_PREPEND,
 	DSA_TAG_PROTO_DSA,
 	DSA_TAG_PROTO_EDSA,
 	DSA_TAG_PROTO_KSZ,
diff --git a/net/dsa/Kconfig b/net/dsa/Kconfig
index cc5f8f971689..2fed892094bc 100644
--- a/net/dsa/Kconfig
+++ b/net/dsa/Kconfig
@@ -19,6 +19,9 @@ if NET_DSA
 config NET_DSA_TAG_BRCM
 	bool
 
+config NET_DSA_TAG_BRCM_PREPEND
+	bool
+
 config NET_DSA_TAG_DSA
 	bool
 
diff --git a/net/dsa/Makefile b/net/dsa/Makefile
index e9a4a0f33e86..0e13c1f95d13 100644
--- a/net/dsa/Makefile
+++ b/net/dsa/Makefile
@@ -5,6 +5,7 @@ dsa_core-y += dsa.o dsa2.o legacy.o master.o port.o slave.o switch.o
 
 # tagging formats
 dsa_core-$(CONFIG_NET_DSA_TAG_BRCM) += tag_brcm.o
+dsa_core-$(CONFIG_NET_DSA_TAG_BRCM_PREPEND) += tag_brcm.o
 dsa_core-$(CONFIG_NET_DSA_TAG_DSA) += tag_dsa.o
 dsa_core-$(CONFIG_NET_DSA_TAG_EDSA) += tag_edsa.o
 dsa_core-$(CONFIG_NET_DSA_TAG_KSZ) += tag_ksz.o
diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index b8f2d9f7c3ed..6a9d0f50fbee 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -44,6 +44,9 @@ const struct dsa_device_ops *dsa_device_ops[DSA_TAG_LAST] = {
 #ifdef CONFIG_NET_DSA_TAG_BRCM
 	[DSA_TAG_PROTO_BRCM] = &brcm_netdev_ops,
 #endif
+#ifdef CONFIG_NET_DSA_TAG_BRCM_PREPEND
+	[DSA_TAG_PROTO_BRCM_PREPEND] = &brcm_prepend_netdev_ops,
+#endif
 #ifdef CONFIG_NET_DSA_TAG_DSA
 	[DSA_TAG_PROTO_DSA] = &dsa_netdev_ops,
 #endif
diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index bb0218c1b570..a0be6b811fc3 100644
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -191,6 +191,7 @@ void dsa_switch_unregister_notifier(struct dsa_switch *ds);
 
 /* tag_brcm.c */
 extern const struct dsa_device_ops brcm_netdev_ops;
+extern const struct dsa_device_ops brcm_prepend_netdev_ops;
 
 /* tag_dsa.c */
 extern const struct dsa_device_ops dsa_netdev_ops;
diff --git a/net/dsa/tag_brcm.c b/net/dsa/tag_brcm.c
index 771409a1e65c..e6e0b7b6025c 100644
--- a/net/dsa/tag_brcm.c
+++ b/net/dsa/tag_brcm.c
@@ -96,13 +96,6 @@ static struct sk_buff *brcm_tag_xmit_ll(struct sk_buff *skb,
 	return skb;
 }
 
-static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb,
-				     struct net_device *dev)
-{
-	/* Build the tag after the MAC Source Address */
-	return brcm_tag_xmit_ll(skb, dev, 2 * ETH_ALEN);
-}
-
 static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,
 				       struct net_device *dev,
 				       struct packet_type *pt,
@@ -139,6 +132,15 @@ static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,
 	return skb;
 }
 
+#ifdef CONFIG_NET_DSA_TAG_BRCM
+static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb,
+				     struct net_device *dev)
+{
+	/* Build the tag after the MAC Source Address */
+	return brcm_tag_xmit_ll(skb, dev, 2 * ETH_ALEN);
+}
+
+
 static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
 				    struct packet_type *pt)
 {
@@ -161,3 +163,26 @@ const struct dsa_device_ops brcm_netdev_ops = {
 	.xmit	= brcm_tag_xmit,
 	.rcv	= brcm_tag_rcv,
 };
+#endif
+
+#ifdef CONFIG_NET_DSA_TAG_BRCM_PREPEND
+static struct sk_buff *brcm_tag_xmit_prepend(struct sk_buff *skb,
+					     struct net_device *dev)
+{
+	/* tag is prepended to the packet */
+	return brcm_tag_xmit_ll(skb, dev, 0);
+}
+
+static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb,
+					    struct net_device *dev,
+					    struct packet_type *pt)
+{
+	/* tag is prepended to the packet */
+	return brcm_tag_rcv_ll(skb, dev, pt, ETH_HLEN);
+}
+
+const struct dsa_device_ops brcm_prepend_netdev_ops = {
+	.xmit	= brcm_tag_xmit_prepend,
+	.rcv	= brcm_tag_rcv_prepend,
+};
+#endif
-- 
2.9.3