[PATCH net-next v12 4/5] net: dsa: tag_yt922x: add support for Motorcomm YT922x tags

@@ -18434,11 +18434,13 @@ F:	drivers/net/phy/motorcomm.c
 
 MOTORCOMM YT921X ETHERNET SWITCH DRIVER
 M:	David Yang <mmyangfl@gmail.com>
+M:	Kyle Switch <kyle.switch@motor-comm.com>
 L:	netdev@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/net/dsa/motorcomm,yt921x.yaml
 F:	drivers/net/dsa/motorcomm/
 F:	net/dsa/tag_yt921x.c
+F:	net/dsa/tag_yt922x.c
 
 MOXA SMARTIO/INDUSTIO/INTELLIO SERIAL CARD
 M:	Jiri Slaby <jirislaby@kernel.org>

@@ -62,6 +62,7 @@ struct tc_action;
 #define DSA_TAG_PROTO_KSZ8463_VALUE		34
 #define DSA_TAG_PROTO_MT7628_VALUE		35
 #define DSA_TAG_PROTO_KS8995_VALUE		36
+#define DSA_TAG_PROTO_YT922X_VALUE		37
 
 enum dsa_tag_protocol {
 	DSA_TAG_PROTO_NONE		= DSA_TAG_PROTO_NONE_VALUE,

@@ -101,6 +102,7 @@ enum dsa_tag_protocol {
 	DSA_TAG_PROTO_KSZ8463		= DSA_TAG_PROTO_KSZ8463_VALUE,
 	DSA_TAG_PROTO_MT7628		= DSA_TAG_PROTO_MT7628_VALUE,
 	DSA_TAG_PROTO_KS8995		= DSA_TAG_PROTO_KS8995_VALUE,
+	DSA_TAG_PROTO_YT922X		= DSA_TAG_PROTO_YT922X_VALUE,
 };
 
 struct dsa_switch;

@@ -233,4 +233,10 @@ config NET_DSA_TAG_YT921X
 	  Say Y or M if you want to enable support for tagging frames for
 	  Motorcomm YT921x switches.
 
+config NET_DSA_TAG_YT922X
+	tristate "Tag driver for Motorcomm YT922x switches"
+	help
+	  Say Y or M if you want to enable support for tagging frames for
+	  Motorcomm YT922x switches.
+
 endif

@@ -45,6 +45,7 @@ obj-$(CONFIG_NET_DSA_TAG_TRAILER) += tag_trailer.o
 obj-$(CONFIG_NET_DSA_TAG_VSC73XX_8021Q) += tag_vsc73xx_8021q.o
 obj-$(CONFIG_NET_DSA_TAG_XRS700X) += tag_xrs700x.o
 obj-$(CONFIG_NET_DSA_TAG_YT921X) += tag_yt921x.o
+obj-$(CONFIG_NET_DSA_TAG_YT922X) += tag_yt922x.o
 
 # for tracing framework to find trace.h
 CFLAGS_trace.o := -I$(src)

@@ -0,0 +1,122 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Motorcomm YT922x Switch Extended CPU Port Tagging
+ *
+ * Copyright (c) 2026 Kyle switch <kyle.switch@motor-comm.com>
+ *
+ */
+
+#include <linux/etherdevice.h>
+
+#include "tag.h"
+
+#define YT922X_TAG_LEN 8
+
+/*
+ * To define the from cpu tag format 8 bytes.
+ *
+ * To-CPU (RX) tag format, 8 bytes:
+ *
+ *   tag[0]: TPID (default: 0x9988)
+ *   tag[1]: VID lookup
+ *   tag[2]: bit 5:2  - RX source port
+ *
+ * From-CPU (TX) tag format, 8 bytes:
+ *
+ *   tag[0]: TPID (default: 0x9988)
+ *   tag[1]: bit 8:0 - Dst port mask
+ *   tag[2]: bit 15  - Dst port 0
+ *
+ */
+#define YT922X_TAG_NAME		"yt922x"
+#define YT922X_TAG_PORTMASK_0	BIT(15)
+#define YT922X_TAG_PORTMASK_M	GENMASK(8, 0)
+#define  YT922X_TAG_PORTS(x)		FIELD_PREP(YT922X_TAG_PORTMASK_M, (x))
+#define YT922X_TAG_FORCE_DST	BIT(9)
+#define YT922X_TAG_PRIO_M	GENMASK(12, 10)
+#define YT922X_TAG_PRIO_EN	BIT(13)
+#define  YT922X_TAG_PRIO(x)	(FIELD_PREP(YT922X_TAG_PRIO_M, (x)) | YT922X_TAG_PRIO_EN)
+#define YT922X_TAG_RX_PORT_M	GENMASK(5, 2)
+
+static struct sk_buff *
+yt922x_tag_xmit(struct sk_buff *skb, struct net_device *netdev)
+{
+	unsigned long ports;
+	__be16 *tag;
+	u16 ctrl;
+
+	skb_push(skb, YT922X_TAG_LEN);
+	dsa_alloc_etype_header(skb, YT922X_TAG_LEN);
+	tag = dsa_etype_header_pos_tx(skb);
+
+	tag[0] = htons(ETH_P_YT921X);
+	ports = dsa_xmit_port_mask(skb, netdev);
+	/*To fill in the case where the port index is not 0 */
+	ctrl = YT922X_TAG_PRIO(skb->priority) | YT922X_TAG_FORCE_DST |
+	       YT922X_TAG_PORTS(ports >> 1);
+	tag[1] = htons(ctrl);
+	if (ports & BIT(0)) {
+		/* To fill in the case where the port index is 0 */
+		ctrl = YT922X_TAG_PORTMASK_0;
+		tag[2] = htons(ctrl);
+	} else {
+		tag[2] = 0;
+	}
+	tag[3] = 0;
+
+	return skb;
+}
+
+static struct sk_buff *
+yt922x_tag_rcv(struct sk_buff *skb, struct net_device *netdev)
+{
+	unsigned int port;
+	__be16 *tag;
+	u16 rx;
+
+	if (unlikely(!pskb_may_pull(skb, YT922X_TAG_LEN))) {
+		kfree_skb(skb);
+		return NULL;
+	}
+
+	tag = dsa_etype_header_pos_rx(skb);
+
+	if (unlikely(tag[0] != htons(ETH_P_YT921X))) {
+		dev_warn_ratelimited(&netdev->dev,
+				     "Unexpected EtherType 0x%04x\n",
+				     ntohs(tag[0]));
+		kfree_skb(skb);
+		return NULL;
+	}
+
+	/* Locate which port this is coming from */
+	rx = ntohs(tag[2]);
+	port = FIELD_GET(YT922X_TAG_RX_PORT_M, rx);
+	skb->dev = dsa_conduit_find_user(netdev, 0, port);
+	if (unlikely(!skb->dev)) {
+		dev_warn_ratelimited(&netdev->dev,
+				     "Couldn't decode source port %u\n", port);
+		kfree_skb(skb);
+		return NULL;
+	}
+
+	/* Remove tag and update checksum */
+	skb_pull_rcsum(skb, YT922X_TAG_LEN);
+	dsa_strip_etype_header(skb, YT922X_TAG_LEN);
+
+	return skb;
+}
+
+static const struct dsa_device_ops yt922x_netdev_ops = {
+	.name = YT922X_TAG_NAME,
+	.proto = DSA_TAG_PROTO_YT922X,
+	.xmit = yt922x_tag_xmit,
+	.rcv = yt922x_tag_rcv,
+	.needed_headroom = YT922X_TAG_LEN,
+};
+
+MODULE_DESCRIPTION("DSA tag driver for Motorcomm YT922x switches");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_YT922X, YT922X_TAG_NAME);
+
+module_dsa_tag_driver(yt922x_netdev_ops);