Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next

Pull networking updates from David Miller:

 1) Support 6Ghz band in ath11k driver, from Rajkumar Manoharan.

 2) Support UDP segmentation in code TSO code, from Eric Dumazet.

 3) Allow flashing different flash images in cxgb4 driver, from Vishal
    Kulkarni.

 4) Add drop frames counter and flow status to tc flower offloading,
    from Po Liu.

 5) Support n-tuple filters in cxgb4, from Vishal Kulkarni.

 6) Various new indirect call avoidance, from Eric Dumazet and Brian
    Vazquez.

 7) Fix BPF verifier failures on 32-bit pointer arithmetic, from
    Yonghong Song.

 8) Support querying and setting hardware address of a port function via
    devlink, use this in mlx5, from Parav Pandit.

 9) Support hw ipsec offload on bonding slaves, from Jarod Wilson.

10) Switch qca8k driver over to phylink, from Jonathan McDowell.

11) In bpftool, show list of processes holding BPF FD references to
    maps, programs, links, and btf objects. From Andrii Nakryiko.

12) Several conversions over to generic power management, from Vaibhav
    Gupta.

13) Add support for SO_KEEPALIVE et al. to bpf_setsockopt(), from Dmitry
    Yakunin.

14) Various https url conversions, from Alexander A. Klimov.

15) Timestamping and PHC support for mscc PHY driver, from Antoine
    Tenart.

16) Support bpf iterating over tcp and udp sockets, from Yonghong Song.

17) Support 5GBASE-T i40e NICs, from Aleksandr Loktionov.

18) Add kTLS RX HW offload support to mlx5e, from Tariq Toukan.

19) Fix the ->ndo_start_xmit() return type to be netdev_tx_t in several
    drivers. From Luc Van Oostenryck.

20) XDP support for xen-netfront, from Denis Kirjanov.

21) Support receive buffer autotuning in MPTCP, from Florian Westphal.

22) Support EF100 chip in sfc driver, from Edward Cree.

23) Add XDP support to mvpp2 driver, from Matteo Croce.

24) Support MPTCP in sock_diag, from Paolo Abeni.

25) Commonize UDP tunnel offloading code by creating udp_tunnel_nic
    infrastructure, from Jakub Kicinski.

26) Several pci_ --> dma_ API conversions, from Christophe JAILLET.

27) Add FLOW_ACTION_POLICE support to mlxsw, from Ido Schimmel.

28) Add SK_LOOKUP bpf program type, from Jakub Sitnicki.

29) Refactor a lot of networking socket option handling code in order to
    avoid set_fs() calls, from Christoph Hellwig.

30) Add rfc4884 support to icmp code, from Willem de Bruijn.

31) Support TBF offload in dpaa2-eth driver, from Ioana Ciornei.

32) Support XDP_REDIRECT in qede driver, from Alexander Lobakin.

33) Support PCI relaxed ordering in mlx5 driver, from Aya Levin.

34) Support TCP syncookies in MPTCP, from Flowian Westphal.

35) Fix several tricky cases of PMTU handling wrt. briding, from Stefano
    Brivio.

* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2056 commits)
  net: thunderx: initialize VF's mailbox mutex before first usage
  usb: hso: remove bogus check for EINPROGRESS
  usb: hso: no complaint about kmalloc failure
  hso: fix bailout in error case of probe
  ip_tunnel_core: Fix build for archs without _HAVE_ARCH_IPV6_CSUM
  selftests/net: relax cpu affinity requirement in msg_zerocopy test
  mptcp: be careful on subflow creation
  selftests: rtnetlink: make kci_test_encap() return sub-test result
  selftests: rtnetlink: correct the final return value for the test
  net: dsa: sja1105: use detected device id instead of DT one on mismatch
  tipc: set ub->ifindex for local ipv6 address
  ipv6: add ipv6_dev_find()
  net: openvswitch: silence suspicious RCU usage warning
  Revert "vxlan: fix tos value before xmit"
  ptp: only allow phase values lower than 1 period
  farsync: switch from 'pci_' to 'dma_' API
  wan: wanxl: switch from 'pci_' to 'dma_' API
  hv_netvsc: do not use VF device if link is down
  dpaa2-eth: Fix passing zero to 'PTR_ERR' warning
  net: macb: Properly handle phylink on at91sam9x
  ...

12 files changed, 199 insertions, 92 deletions

diff --git a/net/dsa/Kconfig b/net/dsa/Kconfig
index d5bc6ac599ef..1f9b9b11008c 100644
--- a/net/dsa/Kconfig
+++ b/net/dsa/Kconfig
@@ -86,6 +86,13 @@ config NET_DSA_TAG_KSZ
 	  Say Y if you want to enable support for tagging frames for the
 	  Microchip 8795/9477/9893 families of switches.
 
+config NET_DSA_TAG_RTL4_A
+	tristate "Tag driver for Realtek 4 byte protocol A tags"
+	help
+	  Say Y or M if you want to enable support for tagging frames for the
+	  Realtek switches with 4 byte protocol A tags, sich as found in
+	  the Realtek RTL8366RB.
+
 config NET_DSA_TAG_OCELOT
 	tristate "Tag driver for Ocelot family of switches"
 	select PACKING
diff --git a/net/dsa/Makefile b/net/dsa/Makefile
index 108486cfdeef..4f47b2025ff5 100644
--- a/net/dsa/Makefile
+++ b/net/dsa/Makefile
@@ -11,6 +11,7 @@ obj-$(CONFIG_NET_DSA_TAG_DSA) += tag_dsa.o
 obj-$(CONFIG_NET_DSA_TAG_EDSA) += tag_edsa.o
 obj-$(CONFIG_NET_DSA_TAG_GSWIP) += tag_gswip.o
 obj-$(CONFIG_NET_DSA_TAG_KSZ) += tag_ksz.o
+obj-$(CONFIG_NET_DSA_TAG_RTL4_A) += tag_rtl4_a.o
 obj-$(CONFIG_NET_DSA_TAG_LAN9303) += tag_lan9303.o
 obj-$(CONFIG_NET_DSA_TAG_MTK) += tag_mtk.o
 obj-$(CONFIG_NET_DSA_TAG_OCELOT) += tag_ocelot.o
diff --git a/net/dsa/dsa2.c b/net/dsa/dsa2.c
index 076908fdd29b..c0ffc7a2b65f 100644
--- a/net/dsa/dsa2.c
+++ b/net/dsa/dsa2.c
@@ -261,10 +261,15 @@ static int dsa_port_setup(struct dsa_port *dp)
 	struct devlink_port *dlp = &dp->devlink_port;
 	bool dsa_port_link_registered = false;
 	bool devlink_port_registered = false;
+	struct devlink_port_attrs attrs = {};
 	struct devlink *dl = ds->devlink;
 	bool dsa_port_enabled = false;
 	int err = 0;
 
+	attrs.phys.port_number = dp->index;
+	memcpy(attrs.switch_id.id, id, len);
+	attrs.switch_id.id_len = len;
+
 	if (dp->setup)
 		return 0;
 
@@ -274,8 +279,8 @@ static int dsa_port_setup(struct dsa_port *dp)
 		break;
 	case DSA_PORT_TYPE_CPU:
 		memset(dlp, 0, sizeof(*dlp));
-		devlink_port_attrs_set(dlp, DEVLINK_PORT_FLAVOUR_CPU,
-				       dp->index, false, 0, id, len);
+		attrs.flavour = DEVLINK_PORT_FLAVOUR_CPU;
+		devlink_port_attrs_set(dlp, &attrs);
 		err = devlink_port_register(dl, dlp, dp->index);
 		if (err)
 			break;
@@ -294,8 +299,8 @@ static int dsa_port_setup(struct dsa_port *dp)
 		break;
 	case DSA_PORT_TYPE_DSA:
 		memset(dlp, 0, sizeof(*dlp));
-		devlink_port_attrs_set(dlp, DEVLINK_PORT_FLAVOUR_DSA,
-				       dp->index, false, 0, id, len);
+		attrs.flavour = DEVLINK_PORT_FLAVOUR_DSA;
+		devlink_port_attrs_set(dlp, &attrs);
 		err = devlink_port_register(dl, dlp, dp->index);
 		if (err)
 			break;
@@ -314,8 +319,8 @@ static int dsa_port_setup(struct dsa_port *dp)
 		break;
 	case DSA_PORT_TYPE_USER:
 		memset(dlp, 0, sizeof(*dlp));
-		devlink_port_attrs_set(dlp, DEVLINK_PORT_FLAVOUR_PHYSICAL,
-				       dp->index, false, 0, id, len);
+		attrs.flavour = DEVLINK_PORT_FLAVOUR_PHYSICAL;
+		devlink_port_attrs_set(dlp, &attrs);
 		err = devlink_port_register(dl, dlp, dp->index);
 		if (err)
 			break;
@@ -722,8 +727,12 @@ static int dsa_switch_parse_ports_of(struct dsa_switch *ds,
 
 	ports = of_get_child_by_name(dn, "ports");
 	if (!ports) {
-		dev_err(ds->dev, "no ports child node found\n");
-		return -EINVAL;
+		/* The second possibility is "ethernet-ports" */
+		ports = of_get_child_by_name(dn, "ethernet-ports");
+		if (!ports) {
+			dev_err(ds->dev, "no ports child node found\n");
+			return -EINVAL;
+		}
 	}
 
 	for_each_available_child_of_node(ports, port) {
diff --git a/net/dsa/dsa_priv.h b/net/dsa/dsa_priv.h
index adecf73bd608..1653e3377cb3 100644
--- a/net/dsa/dsa_priv.h
+++ b/net/dsa/dsa_priv.h
@@ -77,7 +77,7 @@ struct dsa_slave_priv {
 	struct sk_buff *	(*xmit)(struct sk_buff *skb,
 					struct net_device *dev);
 
-	struct pcpu_sw_netstats	*stats64;
+	struct pcpu_sw_netstats	__percpu *stats64;
 
 	struct gro_cells	gcells;
 
diff --git a/net/dsa/master.c b/net/dsa/master.c
index 480a61460c23..61615ebc70e9 100644
--- a/net/dsa/master.c
+++ b/net/dsa/master.c
@@ -186,17 +186,6 @@ static void dsa_master_get_strings(struct net_device *dev, uint32_t stringset,
 	}
 }
 
-static int dsa_master_get_phys_port_name(struct net_device *dev,
-					 char *name, size_t len)
-{
-	struct dsa_port *cpu_dp = dev->dsa_ptr;
-
-	if (snprintf(name, len, "p%d", cpu_dp->index) >= len)
-		return -EINVAL;
-
-	return 0;
-}
-
 static int dsa_master_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 {
 	struct dsa_port *cpu_dp = dev->dsa_ptr;
@@ -220,12 +209,16 @@ static int dsa_master_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 		break;
 	}
 
-	if (cpu_dp->orig_ndo_ops && cpu_dp->orig_ndo_ops->ndo_do_ioctl)
-		err = cpu_dp->orig_ndo_ops->ndo_do_ioctl(dev, ifr, cmd);
+	if (dev->netdev_ops->ndo_do_ioctl)
+		err = dev->netdev_ops->ndo_do_ioctl(dev, ifr, cmd);
 
 	return err;
 }
 
+static const struct dsa_netdevice_ops dsa_netdev_ops = {
+	.ndo_do_ioctl = dsa_master_ioctl,
+};
+
 static int dsa_master_ethtool_setup(struct net_device *dev)
 {
 	struct dsa_port *cpu_dp = dev->dsa_ptr;
@@ -260,38 +253,10 @@ static void dsa_master_ethtool_teardown(struct net_device *dev)
 	cpu_dp->orig_ethtool_ops = NULL;
 }
 
-static int dsa_master_ndo_setup(struct net_device *dev)
+static void dsa_netdev_ops_set(struct net_device *dev,
+			       const struct dsa_netdevice_ops *ops)
 {
-	struct dsa_port *cpu_dp = dev->dsa_ptr;
-	struct dsa_switch *ds = cpu_dp->ds;
-	struct net_device_ops *ops;
-
-	if (dev->netdev_ops->ndo_get_phys_port_name)
-		return 0;
-
-	ops = devm_kzalloc(ds->dev, sizeof(*ops), GFP_KERNEL);
-	if (!ops)
-		return -ENOMEM;
-
-	cpu_dp->orig_ndo_ops = dev->netdev_ops;
-	if (cpu_dp->orig_ndo_ops)
-		memcpy(ops, cpu_dp->orig_ndo_ops, sizeof(*ops));
-
-	ops->ndo_get_phys_port_name = dsa_master_get_phys_port_name;
-	ops->ndo_do_ioctl = dsa_master_ioctl;
-
-	dev->netdev_ops  = ops;
-
-	return 0;
-}
-
-static void dsa_master_ndo_teardown(struct net_device *dev)
-{
-	struct dsa_port *cpu_dp = dev->dsa_ptr;
-
-	if (cpu_dp->orig_ndo_ops)
-		dev->netdev_ops = cpu_dp->orig_ndo_ops;
-	cpu_dp->orig_ndo_ops = NULL;
+	dev->dsa_ptr->netdev_ops = ops;
 }
 
 static ssize_t tagging_show(struct device *d, struct device_attribute *attr,
@@ -353,9 +318,7 @@ int dsa_master_setup(struct net_device *dev, struct dsa_port *cpu_dp)
 	if (ret)
 		return ret;
 
-	ret = dsa_master_ndo_setup(dev);
-	if (ret)
-		goto out_err_ethtool_teardown;
+	dsa_netdev_ops_set(dev, &dsa_netdev_ops);
 
 	ret = sysfs_create_group(&dev->dev.kobj, &dsa_group);
 	if (ret)
@@ -364,8 +327,7 @@ int dsa_master_setup(struct net_device *dev, struct dsa_port *cpu_dp)
 	return ret;
 
 out_err_ndo_teardown:
-	dsa_master_ndo_teardown(dev);
-out_err_ethtool_teardown:
+	dsa_netdev_ops_set(dev, NULL);
 	dsa_master_ethtool_teardown(dev);
 	return ret;
 }
@@ -373,7 +335,7 @@ out_err_ethtool_teardown:
 void dsa_master_teardown(struct net_device *dev)
 {
 	sysfs_remove_group(&dev->dev.kobj, &dsa_group);
-	dsa_master_ndo_teardown(dev);
+	dsa_netdev_ops_set(dev, NULL);
 	dsa_master_ethtool_teardown(dev);
 	dsa_master_reset_mtu(dev);
 
diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index 4c7f086a047b..41d60eeefdbd 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -1754,11 +1754,8 @@ int dsa_slave_create(struct dsa_port *port)
 		eth_hw_addr_inherit(slave_dev, master);
 	slave_dev->priv_flags |= IFF_NO_QUEUE;
 	slave_dev->netdev_ops = &dsa_slave_netdev_ops;
-	slave_dev->min_mtu = 0;
 	if (ds->ops->port_max_mtu)
 		slave_dev->max_mtu = ds->ops->port_max_mtu(ds, port->index);
-	else
-		slave_dev->max_mtu = ETH_MAX_MTU;
 	SET_NETDEV_DEVTYPE(slave_dev, &dsa_type);
 
 	netdev_for_each_tx_queue(slave_dev, dsa_slave_set_lockdep_class_one,
@@ -1795,7 +1792,8 @@ int dsa_slave_create(struct dsa_port *port)
 
 	ret = dsa_slave_phy_setup(slave_dev);
 	if (ret) {
-		netdev_err(master, "error %d setting up slave phy\n", ret);
+		netdev_err(master, "error %d setting up slave PHY for %s\n",
+			   ret, slave_dev->name);
 		goto out_gcells;
 	}
 
diff --git a/net/dsa/tag_ksz.c b/net/dsa/tag_ksz.c
index 90d055c4df9e..bd1a3158d79a 100644
--- a/net/dsa/tag_ksz.c
+++ b/net/dsa/tag_ksz.c
@@ -156,8 +156,9 @@ static struct sk_buff *ksz9477_xmit(struct sk_buff *skb,
 {
 	struct dsa_port *dp = dsa_slave_to_port(dev);
 	struct sk_buff *nskb;
-	u16 *tag;
+	__be16 *tag;
 	u8 *addr;
+	u16 val;
 
 	nskb = ksz_common_xmit(skb, dev, KSZ9477_INGRESS_TAG_LEN);
 	if (!nskb)
@@ -167,12 +168,12 @@ static struct sk_buff *ksz9477_xmit(struct sk_buff *skb,
 	tag = skb_put(nskb, KSZ9477_INGRESS_TAG_LEN);
 	addr = skb_mac_header(nskb);
 
-	*tag = BIT(dp->index);
+	val = BIT(dp->index);
 
 	if (is_link_local_ether_addr(addr))
-		*tag |= KSZ9477_TAIL_TAG_OVERRIDE;
+		val |= KSZ9477_TAIL_TAG_OVERRIDE;
 
-	*tag = cpu_to_be16(*tag);
+	*tag = cpu_to_be16(val);
 
 	return nskb;
 }
diff --git a/net/dsa/tag_lan9303.c b/net/dsa/tag_lan9303.c
index eb0e7a32e53d..ccfb6f641bbf 100644
--- a/net/dsa/tag_lan9303.c
+++ b/net/dsa/tag_lan9303.c
@@ -55,7 +55,8 @@ static int lan9303_xmit_use_arl(struct dsa_port *dp, u8 *dest_addr)
 static struct sk_buff *lan9303_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	struct dsa_port *dp = dsa_slave_to_port(dev);
-	u16 *lan9303_tag;
+	__be16 *lan9303_tag;
+	u16 tag;
 
 	/* insert a special VLAN tag between the MAC addresses
 	 * and the current ethertype field.
@@ -72,12 +73,12 @@ static struct sk_buff *lan9303_xmit(struct sk_buff *skb, struct net_device *dev)
 	/* make room between MACs and Ether-Type */
 	memmove(skb->data, skb->data + LAN9303_TAG_LEN, 2 * ETH_ALEN);
 
-	lan9303_tag = (u16 *)(skb->data + 2 * ETH_ALEN);
+	lan9303_tag = (__be16 *)(skb->data + 2 * ETH_ALEN);
+	tag = lan9303_xmit_use_arl(dp, skb->data) ?
+		LAN9303_TAG_TX_USE_ALR :
+		dp->index | LAN9303_TAG_TX_STP_OVERRIDE;
 	lan9303_tag[0] = htons(ETH_P_8021Q);
-	lan9303_tag[1] = lan9303_xmit_use_arl(dp, skb->data) ?
-				LAN9303_TAG_TX_USE_ALR :
-				dp->index | LAN9303_TAG_TX_STP_OVERRIDE;
-	lan9303_tag[1] = htons(lan9303_tag[1]);
+	lan9303_tag[1] = htons(tag);
 
 	return skb;
 }
@@ -85,7 +86,7 @@ static struct sk_buff *lan9303_xmit(struct sk_buff *skb, struct net_device *dev)
 static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev,
 				   struct packet_type *pt)
 {
-	u16 *lan9303_tag;
+	__be16 *lan9303_tag;
 	u16 lan9303_tag1;
 	unsigned int source_port;
 
@@ -101,7 +102,7 @@ static struct sk_buff *lan9303_rcv(struct sk_buff *skb, struct net_device *dev,
 	 *                           ^
 	 *                        ->data
 	 */
-	lan9303_tag = (u16 *)(skb->data - 2);
+	lan9303_tag = (__be16 *)(skb->data - 2);
 
 	if (lan9303_tag[0] != htons(ETH_P_8021Q)) {
 		dev_warn_ratelimited(&dev->dev, "Dropping packet due to invalid VLAN marker\n");
diff --git a/net/dsa/tag_mtk.c b/net/dsa/tag_mtk.c
index d6619edd53e5..f602fc758d68 100644
--- a/net/dsa/tag_mtk.c
+++ b/net/dsa/tag_mtk.c
@@ -67,8 +67,9 @@ static struct sk_buff *mtk_tag_xmit(struct sk_buff *skb,
 static struct sk_buff *mtk_tag_rcv(struct sk_buff *skb, struct net_device *dev,
 				   struct packet_type *pt)
 {
+	u16 hdr;
 	int port;
-	__be16 *phdr, hdr;
+	__be16 *phdr;
 	unsigned char *dest = eth_hdr(skb)->h_dest;
 	bool is_multicast_skb = is_multicast_ether_addr(dest) &&
 				!is_broadcast_ether_addr(dest);
diff --git a/net/dsa/tag_ocelot.c b/net/dsa/tag_ocelot.c
index b0c98ee4e13b..42f327c06dca 100644
--- a/net/dsa/tag_ocelot.c
+++ b/net/dsa/tag_ocelot.c
@@ -137,11 +137,10 @@ static struct sk_buff *ocelot_xmit(struct sk_buff *skb,
 				   struct net_device *netdev)
 {
 	struct dsa_port *dp = dsa_slave_to_port(netdev);
-	u64 bypass, dest, src, qos_class, rew_op;
 	struct dsa_switch *ds = dp->ds;
-	int port = dp->index;
 	struct ocelot *ocelot = ds->priv;
-	struct ocelot_port *ocelot_port = ocelot->ports[port];
+	struct ocelot_port *ocelot_port;
+	u64 qos_class, rew_op;
 	u8 *injection;
 
 	if (unlikely(skb_cow_head(skb, OCELOT_TAG_LEN) < 0)) {
@@ -149,19 +148,15 @@ static struct sk_buff *ocelot_xmit(struct sk_buff *skb,
 		return NULL;
 	}
 
-	injection = skb_push(skb, OCELOT_TAG_LEN);
+	ocelot_port = ocelot->ports[dp->index];
 
-	memset(injection, 0, OCELOT_TAG_LEN);
+	injection = skb_push(skb, OCELOT_TAG_LEN);
 
-	/* Set the source port as the CPU port module and not the NPI port */
-	src = ocelot->num_phys_ports;
-	dest = BIT(port);
-	bypass = true;
+	memcpy(injection, ocelot_port->xmit_template, OCELOT_TAG_LEN);
+	/* Fix up the fields which are not statically determined
+	 * in the template
+	 */
 	qos_class = skb->priority;
-
-	packing(injection, &bypass,   127, 127, OCELOT_TAG_LEN, PACK, 0);
-	packing(injection, &dest,      68,  56, OCELOT_TAG_LEN, PACK, 0);
-	packing(injection, &src,       46,  43, OCELOT_TAG_LEN, PACK, 0);
 	packing(injection, &qos_class, 19,  17, OCELOT_TAG_LEN, PACK, 0);
 
 	if (ocelot->ptp && (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)) {
diff --git a/net/dsa/tag_qca.c b/net/dsa/tag_qca.c
index 70db7c909f74..7066f5e697d7 100644
--- a/net/dsa/tag_qca.c
+++ b/net/dsa/tag_qca.c
@@ -31,7 +31,8 @@
 static struct sk_buff *qca_tag_xmit(struct sk_buff *skb, struct net_device *dev)
 {
 	struct dsa_port *dp = dsa_slave_to_port(dev);
-	u16 *phdr, hdr;
+	__be16 *phdr;
+	u16 hdr;
 
 	if (skb_cow_head(skb, QCA_HDR_LEN) < 0)
 		return NULL;
@@ -39,7 +40,7 @@ static struct sk_buff *qca_tag_xmit(struct sk_buff *skb, struct net_device *dev)
 	skb_push(skb, QCA_HDR_LEN);
 
 	memmove(skb->data, skb->data + QCA_HDR_LEN, 2 * ETH_ALEN);
-	phdr = (u16 *)(skb->data + 2 * ETH_ALEN);
+	phdr = (__be16 *)(skb->data + 2 * ETH_ALEN);
 
 	/* Set the version field, and set destination port information */
 	hdr = QCA_HDR_VERSION << QCA_HDR_XMIT_VERSION_S |
@@ -54,8 +55,9 @@ static struct sk_buff *qca_tag_rcv(struct sk_buff *skb, struct net_device *dev,
 				   struct packet_type *pt)
 {
 	u8 ver;
+	u16  hdr;
 	int port;
-	__be16 *phdr, hdr;
+	__be16 *phdr;
 
 	if (unlikely(!pskb_may_pull(skb, QCA_HDR_LEN)))
 		return NULL;
diff --git a/net/dsa/tag_rtl4_a.c b/net/dsa/tag_rtl4_a.c
new file mode 100644
index 000000000000..7b63010fa87b
--- /dev/null
+++ b/net/dsa/tag_rtl4_a.c
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Handler for Realtek 4 byte DSA switch tags
+ * Currently only supports protocol "A" found in RTL8366RB
+ * Copyright (c) 2020 Linus Walleij <linus.walleij@linaro.org>
+ *
+ * This "proprietary tag" header looks like so:
+ *
+ * -------------------------------------------------
+ * | MAC DA | MAC SA | 0x8899 | 2 bytes tag | Type |
+ * -------------------------------------------------
+ *
+ * The 2 bytes tag form a 16 bit big endian word. The exact
+ * meaning has been guessed from packet dumps from ingress
+ * frames, as no working egress traffic has been available
+ * we do not know the format of the egress tags or if they
+ * are even supported.
+ */
+
+#include <linux/etherdevice.h>
+#include <linux/bits.h>
+
+#include "dsa_priv.h"
+
+#define RTL4_A_HDR_LEN		4
+#define RTL4_A_ETHERTYPE	0x8899
+#define RTL4_A_PROTOCOL_SHIFT	12
+/*
+ * 0x1 = Realtek Remote Control protocol (RRCP)
+ * 0x2/0x3 seems to be used for loopback testing
+ * 0x9 = RTL8306 DSA protocol
+ * 0xa = RTL8366RB DSA protocol
+ */
+#define RTL4_A_PROTOCOL_RTL8366RB	0xa
+
+static struct sk_buff *rtl4a_tag_xmit(struct sk_buff *skb,
+				      struct net_device *dev)
+{
+	/*
+	 * Just let it pass thru, we don't know if it is possible
+	 * to tag a frame with the 0x8899 ethertype and direct it
+	 * to a specific port, all attempts at reverse-engineering have
+	 * ended up with the frames getting dropped.
+	 *
+	 * The VLAN set-up needs to restrict the frames to the right port.
+	 *
+	 * If you have documentation on the tagging format for RTL8366RB
+	 * (tag type A) then please contribute.
+	 */
+	return skb;
+}
+
+static struct sk_buff *rtl4a_tag_rcv(struct sk_buff *skb,
+				     struct net_device *dev,
+				     struct packet_type *pt)
+{
+	u16 protport;
+	__be16 *p;
+	u16 etype;
+	u8 *tag;
+	u8 prot;
+	u8 port;
+
+	if (unlikely(!pskb_may_pull(skb, RTL4_A_HDR_LEN)))
+		return NULL;
+
+	/* The RTL4 header has its own custom Ethertype 0x8899 and that
+	 * starts right at the beginning of the packet, after the src
+	 * ethernet addr. Apparantly skb->data always points 2 bytes in,
+	 * behind the Ethertype.
+	 */
+	tag = skb->data - 2;
+	p = (__be16 *)tag;
+	etype = ntohs(*p);
+	if (etype != RTL4_A_ETHERTYPE) {
+		/* Not custom, just pass through */
+		netdev_dbg(dev, "non-realtek ethertype 0x%04x\n", etype);
+		return skb;
+	}
+	p = (__be16 *)(tag + 2);
+	protport = ntohs(*p);
+	/* The 4 upper bits are the protocol */
+	prot = (protport >> RTL4_A_PROTOCOL_SHIFT) & 0x0f;
+	if (prot != RTL4_A_PROTOCOL_RTL8366RB) {
+		netdev_err(dev, "unknown realtek protocol 0x%01x\n", prot);
+		return NULL;
+	}
+	port = protport & 0xff;
+
+	skb->dev = dsa_master_find_slave(dev, 0, port);
+	if (!skb->dev) {
+		netdev_dbg(dev, "could not find slave for port %d\n", port);
+		return NULL;
+	}
+
+	/* Remove RTL4 tag and recalculate checksum */
+	skb_pull_rcsum(skb, RTL4_A_HDR_LEN);
+
+	/* Move ethernet DA and SA in front of the data */
+	memmove(skb->data - ETH_HLEN,
+		skb->data - ETH_HLEN - RTL4_A_HDR_LEN,
+		2 * ETH_ALEN);
+
+	skb->offload_fwd_mark = 1;
+
+	return skb;
+}
+
+static int rtl4a_tag_flow_dissect(const struct sk_buff *skb, __be16 *proto,
+				  int *offset)
+{
+	*offset = RTL4_A_HDR_LEN;
+	/* Skip past the tag and fetch the encapsulated Ethertype */
+	*proto = ((__be16 *)skb->data)[1];
+
+	return 0;
+}
+
+static const struct dsa_device_ops rtl4a_netdev_ops = {
+	.name	= "rtl4a",
+	.proto	= DSA_TAG_PROTO_RTL4_A,
+	.xmit	= rtl4a_tag_xmit,
+	.rcv	= rtl4a_tag_rcv,
+	.flow_dissect = rtl4a_tag_flow_dissect,
+	.overhead = RTL4_A_HDR_LEN,
+};
+module_dsa_tag_driver(rtl4a_netdev_ops);
+
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_RTL4_A);