1 files changed, 63 insertions, 0 deletions
diff --git a/net/dsa/tag_trailer.c b/net/dsa/tag_trailer.c
new file mode 100644
index 000000000..5749ba85c
--- /dev/null
+++ b/net/dsa/tag_trailer.c
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * net/dsa/tag_trailer.c - Trailer tag format handling
+ * Copyright (c) 2008-2009 Marvell Semiconductor
+ */
+
+#include <linux/etherdevice.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+
+#include "dsa_priv.h"
+
+static struct sk_buff *trailer_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct dsa_port *dp = dsa_slave_to_port(dev);
+	u8 *trailer;
+
+	trailer = skb_put(skb, 4);
+	trailer[0] = 0x80;
+	trailer[1] = 1 << dp->index;
+	trailer[2] = 0x10;
+	trailer[3] = 0x00;
+
+	return skb;
+}
+
+static struct sk_buff *trailer_rcv(struct sk_buff *skb, struct net_device *dev)
+{
+	u8 *trailer;
+	int source_port;
+
+	if (skb_linearize(skb))
+		return NULL;
+
+	trailer = skb_tail_pointer(skb) - 4;
+	if (trailer[0] != 0x80 || (trailer[1] & 0xf8) != 0x00 ||
+	    (trailer[2] & 0xef) != 0x00 || trailer[3] != 0x00)
+		return NULL;
+
+	source_port = trailer[1] & 7;
+
+	skb->dev = dsa_master_find_slave(dev, 0, source_port);
+	if (!skb->dev)
+		return NULL;
+
+	if (pskb_trim_rcsum(skb, skb->len - 4))
+		return NULL;
+
+	return skb;
+}
+
+static const struct dsa_device_ops trailer_netdev_ops = {
+	.name	= "trailer",
+	.proto	= DSA_TAG_PROTO_TRAILER,
+	.xmit	= trailer_xmit,
+	.rcv	= trailer_rcv,
+	.needed_tailroom = 4,
+};
+
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_TRAILER);
+
+module_dsa_tag_driver(trailer_netdev_ops);