1 files changed, 73 insertions, 0 deletions
diff --git a/net/dsa/tag_hellcreek.c b/net/dsa/tag_hellcreek.c
new file mode 100644
index 000000000..03a1fb9c8
--- /dev/null
+++ b/net/dsa/tag_hellcreek.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: (GPL-2.0 OR MIT)
+/*
+ * net/dsa/tag_hellcreek.c - Hirschmann Hellcreek switch tag format handling
+ *
+ * Copyright (C) 2019,2020 Linutronix GmbH
+ * Author Kurt Kanzenbach <kurt@linutronix.de>
+ *
+ * Based on tag_ksz.c.
+ */
+
+#include <linux/skbuff.h>
+#include <net/dsa.h>
+
+#include "tag.h"
+
+#define HELLCREEK_NAME		"hellcreek"
+
+#define HELLCREEK_TAG_LEN	1
+
+static struct sk_buff *hellcreek_xmit(struct sk_buff *skb,
+				      struct net_device *dev)
+{
+	struct dsa_port *dp = dsa_slave_to_port(dev);
+	u8 *tag;
+
+	/* Calculate checksums (if required) before adding the trailer tag to
+	 * avoid including it in calculations. That would lead to wrong
+	 * checksums after the switch strips the tag.
+	 */
+	if (skb->ip_summed == CHECKSUM_PARTIAL &&
+	    skb_checksum_help(skb))
+		return NULL;
+
+	/* Tag encoding */
+	tag  = skb_put(skb, HELLCREEK_TAG_LEN);
+	*tag = BIT(dp->index);
+
+	return skb;
+}
+
+static struct sk_buff *hellcreek_rcv(struct sk_buff *skb,
+				     struct net_device *dev)
+{
+	/* Tag decoding */
+	u8 *tag = skb_tail_pointer(skb) - HELLCREEK_TAG_LEN;
+	unsigned int port = tag[0] & 0x03;
+
+	skb->dev = dsa_master_find_slave(dev, 0, port);
+	if (!skb->dev) {
+		netdev_warn_once(dev, "Failed to get source port: %d\n", port);
+		return NULL;
+	}
+
+	if (pskb_trim_rcsum(skb, skb->len - HELLCREEK_TAG_LEN))
+		return NULL;
+
+	dsa_default_offload_fwd_mark(skb);
+
+	return skb;
+}
+
+static const struct dsa_device_ops hellcreek_netdev_ops = {
+	.name	  = HELLCREEK_NAME,
+	.proto	  = DSA_TAG_PROTO_HELLCREEK,
+	.xmit	  = hellcreek_xmit,
+	.rcv	  = hellcreek_rcv,
+	.needed_tailroom = HELLCREEK_TAG_LEN,
+};
+
+MODULE_LICENSE("Dual MIT/GPL");
+MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_HELLCREEK, HELLCREEK_NAME);
+
+module_dsa_tag_driver(hellcreek_netdev_ops);