diff --git a/include/net/dsa.h b/include/net/dsa.h
index 0c2cba45fa79..6d8b5a11d99a 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -51,6 +51,7 @@ struct phylink_link_state;
 #define DSA_TAG_PROTO_SEVILLE_VALUE		21
 #define DSA_TAG_PROTO_BRCM_LEGACY_VALUE		22
 #define DSA_TAG_PROTO_SJA1110_VALUE		23
+#define DSA_TAG_PROTO_RTL8_4_VALUE		24
 
 enum dsa_tag_protocol {
 	DSA_TAG_PROTO_NONE		= DSA_TAG_PROTO_NONE_VALUE,
@@ -77,6 +78,7 @@ enum dsa_tag_protocol {
 	DSA_TAG_PROTO_OCELOT_8021Q	= DSA_TAG_PROTO_OCELOT_8021Q_VALUE,
 	DSA_TAG_PROTO_SEVILLE		= DSA_TAG_PROTO_SEVILLE_VALUE,
 	DSA_TAG_PROTO_SJA1110		= DSA_TAG_PROTO_SJA1110_VALUE,
+	DSA_TAG_PROTO_RTL8_4		= DSA_TAG_PROTO_RTL8_4_VALUE,
 };
 
 struct dsa_switch;
diff --git a/net/dsa/Kconfig b/net/dsa/Kconfig
index 548285539752..470a2f3e8f75 100644
--- a/net/dsa/Kconfig
+++ b/net/dsa/Kconfig
@@ -99,6 +99,12 @@ config NET_DSA_TAG_RTL4_A
 	  Realtek switches with 4 byte protocol A tags, sich as found in
 	  the Realtek RTL8366RB.
 
+config NET_DSA_TAG_RTL8_4
+	tristate "Tag driver for Realtek 8 byte protocol 4 tags"
+	help
+	  Say Y or M if you want to enable support for tagging frames for Realtek
+	  switches with 8 byte protocol 4 tags, such as the Realtek RTL8365MB-VC.
+
 config NET_DSA_TAG_OCELOT
 	tristate "Tag driver for Ocelot family of switches, using NPI port"
 	depends on MSCC_OCELOT_SWITCH_LIB || \
diff --git a/net/dsa/Makefile b/net/dsa/Makefile
index 67ea009f242c..01282817e80e 100644
--- a/net/dsa/Makefile
+++ b/net/dsa/Makefile
@@ -11,6 +11,7 @@ obj-$(CONFIG_NET_DSA_TAG_GSWIP) += tag_gswip.o
 obj-$(CONFIG_NET_DSA_TAG_HELLCREEK) += tag_hellcreek.o
 obj-$(CONFIG_NET_DSA_TAG_KSZ) += tag_ksz.o
 obj-$(CONFIG_NET_DSA_TAG_RTL4_A) += tag_rtl4_a.o
+obj-$(CONFIG_NET_DSA_TAG_RTL8_4) += tag_rtl8_4.o
 obj-$(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/tag_rtl8_4.c b/net/dsa/tag_rtl8_4.c
new file mode 100644
index 000000000000..1082bafb6a2e
--- /dev/null
+++ b/net/dsa/tag_rtl8_4.c
@@ -0,0 +1,178 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Handler for Realtek 8 byte switch tags
+ *
+ * Copyright (C) 2021 Alvin Šipraga <alsi@bang-olufsen.dk>
+ *
+ * NOTE: Currently only supports protocol "4" found in the RTL8365MB, hence
+ * named tag_rtl8_4.
+ *
+ * This "proprietary tag" header has the following format:
+ *
+ *  -------------------------------------------
+ *  | MAC DA | MAC SA | 8 byte tag | Type | ...
+ *  -------------------------------------------
+ *     _______________/            \______________________________________
+ *    /                                                                   \
+ *  0                                  7|8                                 15
+ *  |-----------------------------------+-----------------------------------|---
+ *  |                               (16-bit)                                | ^
+ *  |                       Realtek EtherType [0x8899]                      | |
+ *  |-----------------------------------+-----------------------------------| 8
+ *  |              (8-bit)              |              (8-bit)              |
+ *  |          Protocol [0x04]          |              REASON               | b
+ *  |-----------------------------------+-----------------------------------| y
+ *  |   (1)  | (1) | (2) |   (1)  | (3) | (1)  | (1) |    (1)    |   (5)    | t
+ *  | FID_EN |  X  | FID | PRI_EN | PRI | KEEP |  X  | LEARN_DIS |    X     | e
+ *  |-----------------------------------+-----------------------------------| s
+ *  |   (1)  |                       (15-bit)                               | |
+ *  |  ALLOW |                        TX/RX                                 | v
+ *  |-----------------------------------+-----------------------------------|---
+ *
+ * With the following field descriptions:
+ *
+ *    field      | description
+ *   ------------+-------------
+ *    Realtek    | 0x8899: indicates that this is a proprietary Realtek tag;
+ *     EtherType |         note that Realtek uses the same EtherType for
+ *               |         other incompatible tag formats (e.g. tag_rtl4_a.c)
+ *    Protocol   | 0x04: indicates that this tag conforms to this format
+ *    X          | reserved
+ *   ------------+-------------
+ *    REASON     | reason for forwarding packet to CPU
+ *    FID_EN     | 1: packet has an FID
+ *               | 0: no FID
+ *    FID        | FID of packet (if FID_EN=1)
+ *    PRI_EN     | 1: force priority of packet
+ *               | 0: don't force priority
+ *    PRI        | priority of packet (if PRI_EN=1)
+ *    KEEP       | preserve packet VLAN tag format
+ *    LEARN_DIS  | don't learn the source MAC address of the packet
+ *    ALLOW      | 1: treat TX/RX field as an allowance port mask, meaning the
+ *               |    packet may only be forwarded to ports specified in the
+ *               |    mask
+ *               | 0: no allowance port mask, TX/RX field is the forwarding
+ *               |    port mask
+ *    TX/RX      | TX (switch->CPU): port number the packet was received on
+ *               | RX (CPU->switch): forwarding port mask (if ALLOW=0)
+ *               |                   allowance port mask (if ALLOW=1)
+ */
+
+#include <linux/etherdevice.h>
+#include <linux/bits.h>
+
+#include "dsa_priv.h"
+
+#define RTL8_4_TAG_LEN			8
+#define RTL8_4_ETHERTYPE		0x8899
+/* 0x04 = RTL8365MB DSA protocol
+ */
+#define RTL8_4_PROTOCOL_RTL8365MB	0x04
+
+static struct sk_buff *rtl8_4_tag_xmit(struct sk_buff *skb,
+				       struct net_device *dev)
+{
+	struct dsa_port *dp = dsa_slave_to_port(dev);
+	__be16 *p;
+	u8 *tag;
+	u16 out;
+
+	/* Pad out so that the (stripped) packet is at least 64 bytes long
+	 * (including FCS), otherwise the switch will drop the packet.
+	 * Then we need an additional 8 bytes for the Realtek tag.
+	 */
+	if (__skb_put_padto(skb, ETH_ZLEN + RTL8_4_TAG_LEN, false))
+		return NULL;
+
+	skb_push(skb, RTL8_4_TAG_LEN);
+
+	dsa_alloc_etype_header(skb, RTL8_4_TAG_LEN);
+	tag = dsa_etype_header_pos_tx(skb);
+
+	/* Set Realtek EtherType */
+	p = (__be16 *)tag;
+	*p = htons(RTL8_4_ETHERTYPE);
+
+	/* Set Protocol; zero REASON */
+	p = (__be16 *)(tag + 2);
+	*p = htons(RTL8_4_PROTOCOL_RTL8365MB << 8);
+
+	/* Zero FID_EN, FID, PRI_EN, PRI, KEEP, LEARN_DIS */
+	p = (__be16 *)(tag + 4);
+	*p = 0;
+
+	/* Zero ALLOW; set RX (CPU->switch) forwarding port mask */
+	p = (__be16 *)(tag + 6);
+	out = BIT(dp->index);
+	*p = htons(~(1 << 15) & BIT(dp->index));
+
+	return skb;
+}
+
+static struct sk_buff *rtl8_4_tag_rcv(struct sk_buff *skb,
+				      struct net_device *dev)
+{
+	__be16 *p;
+	u16 etype;
+	u8 proto;
+	u8 *tag;
+	u8 port;
+	u16 tmp;
+
+	if (unlikely(!pskb_may_pull(skb, RTL8_4_TAG_LEN)))
+		return NULL;
+
+	tag = dsa_etype_header_pos_rx(skb);
+
+	/* Parse Realtek EtherType */
+	p = (__be16 *)tag;
+	etype = ntohs(*p);
+	if (unlikely(etype != RTL8_4_ETHERTYPE)) {
+		netdev_dbg(dev, "non-realtek ethertype 0x%04x\n", etype);
+		return NULL;
+	}
+
+	/* Parse Protocol; ignore REASON */
+	p = (__be16 *)(tag + 2);
+	tmp = ntohs(*p);
+	proto = tmp >> 8;
+	if (unlikely(proto != RTL8_4_PROTOCOL_RTL8365MB)) {
+		netdev_dbg(dev, "unknown realtek protocol 0x%02x\n", proto);
+		return NULL;
+	}
+
+	/* Ignore FID_EN, FID, PRI_EN, PRI, KEEP, LEARN_DIS */
+	p = (__be16 *)(tag + 4);
+
+	/* Ignore ALLOW; parse TX (switch->CPU) */
+	p = (__be16 *)(tag + 6);
+	tmp = ntohs(*p);
+	port = tmp & 0xf; /* Port number is the LSB 4 bits */
+
+	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 tag and recalculate checksum */
+	skb_pull_rcsum(skb, RTL8_4_TAG_LEN);
+
+	dsa_strip_etype_header(skb, RTL8_4_TAG_LEN);
+
+	skb->offload_fwd_mark = 1;
+
+	return skb;
+}
+
+static const struct dsa_device_ops rtl8_4_netdev_ops = {
+	.name = "rtl8_4",
+	.proto = DSA_TAG_PROTO_RTL8_4,
+	.xmit = rtl8_4_tag_xmit,
+	.rcv = rtl8_4_tag_rcv,
+	.needed_headroom = RTL8_4_TAG_LEN,
+};
+module_dsa_tag_driver(rtl8_4_netdev_ops);
+
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_RTL8_4);
