1 files changed, 100 insertions, 0 deletions
diff --git a/net/dsa/tag_mtk.c b/net/dsa/tag_mtk.c
new file mode 100644
index 000000000000..837cdddb53f0
--- /dev/null
+++ b/net/dsa/tag_mtk.c
@@ -0,0 +1,100 @@
+/*
+ * Mediatek DSA Tag support
+ * Copyright (C) 2017 Landen Chao <landen.chao@mediatek.com>
+ *		      Sean Wang <sean.wang@mediatek.com>
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/etherdevice.h>
+#include <net/dsa.h>
+#include "dsa_priv.h"
+
+#define MTK_HDR_LEN		4
+#define MTK_HDR_RECV_SOURCE_PORT_MASK	GENMASK(2, 0)
+#define MTK_HDR_XMIT_DP_BIT_MASK	GENMASK(5, 0)
+
+static struct sk_buff *mtk_tag_xmit(struct sk_buff *skb,
+				    struct net_device *dev)
+{
+	struct dsa_slave_priv *p = netdev_priv(dev);
+	u8 *mtk_tag;
+
+	if (skb_cow_head(skb, MTK_HDR_LEN) < 0)
+		goto out_free;
+
+	skb_push(skb, MTK_HDR_LEN);
+
+	memmove(skb->data, skb->data + MTK_HDR_LEN, 2 * ETH_ALEN);
+
+	/* Build the tag after the MAC Source Address */
+	mtk_tag = skb->data + 2 * ETH_ALEN;
+	mtk_tag[0] = 0;
+	mtk_tag[1] = (1 << p->dp->index) & MTK_HDR_XMIT_DP_BIT_MASK;
+	mtk_tag[2] = 0;
+	mtk_tag[3] = 0;
+
+	return skb;
+
+out_free:
+	kfree_skb(skb);
+	return NULL;
+}
+
+static struct sk_buff *mtk_tag_rcv(struct sk_buff *skb, struct net_device *dev,
+				   struct packet_type *pt,
+				   struct net_device *orig_dev)
+{
+	struct dsa_switch_tree *dst = dev->dsa_ptr;
+	struct dsa_switch *ds;
+	int port;
+	__be16 *phdr, hdr;
+
+	if (unlikely(!pskb_may_pull(skb, MTK_HDR_LEN)))
+		goto out_drop;
+
+	/* The MTK header is added by the switch between src addr
+	 * and ethertype at this point, skb->data points to 2 bytes
+	 * after src addr so header should be 2 bytes right before.
+	 */
+	phdr = (__be16 *)(skb->data - 2);
+	hdr = ntohs(*phdr);
+
+	/* Remove MTK tag and recalculate checksum. */
+	skb_pull_rcsum(skb, MTK_HDR_LEN);
+
+	memmove(skb->data - ETH_HLEN,
+		skb->data - ETH_HLEN - MTK_HDR_LEN,
+		2 * ETH_ALEN);
+
+	/* This protocol doesn't support cascading multiple
+	 * switches so it's safe to assume the switch is first
+	 * in the tree.
+	 */
+	ds = dst->ds[0];
+	if (!ds)
+		goto out_drop;
+
+	/* Get source port information */
+	port = (hdr & MTK_HDR_RECV_SOURCE_PORT_MASK);
+	if (!ds->ports[port].netdev)
+		goto out_drop;
+
+	skb->dev = ds->ports[port].netdev;
+
+	return skb;
+
+out_drop:
+	return NULL;
+}
+
+const struct dsa_device_ops mtk_netdev_ops = {
+	.xmit	= mtk_tag_xmit,
+	.rcv	= mtk_tag_rcv,
+};