--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Intel / Lantiq GSWIP V2.0 PMAC tag support
+ *
+ * Copyright (C) 2017 - 2018 Hauke Mehrtens <hauke@hauke-m.de>
+ */
+
+#include <linux/bitops.h>
+#include <linux/etherdevice.h>
+#include <linux/skbuff.h>
+#include <net/dsa.h>
+
+#include "dsa_priv.h"
+
+#define GSWIP_TX_HEADER_LEN 4
+
+/* special tag in TX path header */
+/* Byte 0 */
+#define GSWIP_TX_SLPID_SHIFT 0 /* source port ID */
+#define GSWIP_TX_SLPID_CPU 2
+#define GSWIP_TX_SLPID_APP1 3
+#define GSWIP_TX_SLPID_APP2 4
+#define GSWIP_TX_SLPID_APP3 5
+#define GSWIP_TX_SLPID_APP4 6
+#define GSWIP_TX_SLPID_APP5 7
+
+/* Byte 1 */
+#define GSWIP_TX_CRCGEN_DIS BIT(7)
+#define GSWIP_TX_DPID_SHIFT 0 /* destination group ID */
+#define GSWIP_TX_DPID_ELAN 0
+#define GSWIP_TX_DPID_EWAN 1
+#define GSWIP_TX_DPID_CPU 2
+#define GSWIP_TX_DPID_APP1 3
+#define GSWIP_TX_DPID_APP2 4
+#define GSWIP_TX_DPID_APP3 5
+#define GSWIP_TX_DPID_APP4 6
+#define GSWIP_TX_DPID_APP5 7
+
+/* Byte 2 */
+#define GSWIP_TX_PORT_MAP_EN BIT(7)
+#define GSWIP_TX_PORT_MAP_SEL BIT(6)
+#define GSWIP_TX_LRN_DIS BIT(5)
+#define GSWIP_TX_CLASS_EN BIT(4)
+#define GSWIP_TX_CLASS_SHIFT 0
+#define GSWIP_TX_CLASS_MASK GENMASK(3, 0)
+
+/* Byte 3 */
+#define GSWIP_TX_DPID_EN BIT(0)
+#define GSWIP_TX_PORT_MAP_SHIFT 1
+#define GSWIP_TX_PORT_MAP_MASK GENMASK(6, 1)
+
+#define GSWIP_RX_HEADER_LEN 8
+
+/* special tag in RX path header */
+/* Byte 7 */
+#define GSWIP_RX_SPPID_SHIFT 4
+#define GSWIP_RX_SPPID_MASK GENMASK(6, 4)
+
+static struct sk_buff *gswip_tag_xmit(struct sk_buff *skb,
+ struct net_device *dev)
+{
+ struct dsa_port *dp = dsa_slave_to_port(dev);
+ int err;
+ u8 *gswip_tag;
+
+ err = skb_cow_head(skb, GSWIP_TX_HEADER_LEN);
+ if (err)
+ return NULL;
+
+ skb_push(skb, GSWIP_TX_HEADER_LEN);
+
+ gswip_tag = skb->data;
+ gswip_tag[0] = GSWIP_TX_SLPID_CPU;
+ gswip_tag[1] = GSWIP_TX_DPID_ELAN;
+ gswip_tag[2] = GSWIP_TX_PORT_MAP_EN | GSWIP_TX_PORT_MAP_SEL;
+ gswip_tag[3] = BIT(dp->index + GSWIP_TX_PORT_MAP_SHIFT) & GSWIP_TX_PORT_MAP_MASK;
+ gswip_tag[3] |= GSWIP_TX_DPID_EN;
+
+ return skb;
+}
+
+static struct sk_buff *gswip_tag_rcv(struct sk_buff *skb,
+ struct net_device *dev,
+ struct packet_type *pt)
+{
+ int port;
+ u8 *gswip_tag;
+
+ if (unlikely(!pskb_may_pull(skb, GSWIP_RX_HEADER_LEN)))
+ return NULL;
+
+ gswip_tag = skb->data - ETH_HLEN;
+
+ /* Get source port information */
+ port = (gswip_tag[7] & GSWIP_RX_SPPID_MASK) >> GSWIP_RX_SPPID_SHIFT;
+ skb->dev = dsa_master_find_slave(dev, 0, port);
+ if (!skb->dev)
+ return NULL;
+
+ /* remove GSWIP tag */
+ skb_pull_rcsum(skb, GSWIP_RX_HEADER_LEN);
+
+ return skb;
+}
+
+const struct dsa_device_ops gswip_netdev_ops = {
+ .xmit = gswip_tag_xmit,
+ .rcv = gswip_tag_rcv,
+};