net: dsa: tag_yt921x: add support for Motorcomm YT921x tags (ca470984) · Commits · git / linux-net

include/net/dsa.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -55,6 +55,7 @@ struct tc_action;
		#define DSA_TAG_PROTO_LAN937X_VALUE 27
		#define DSA_TAG_PROTO_VSC73XX_8021Q_VALUE 28
		#define DSA_TAG_PROTO_BRCM_LEGACY_FCS_VALUE 29
		#define DSA_TAG_PROTO_YT921X_VALUE 30

		enum dsa_tag_protocol {
		DSA_TAG_PROTO_NONE = DSA_TAG_PROTO_NONE_VALUE,
		@@ -87,6 +88,7 @@ enum dsa_tag_protocol {
		DSA_TAG_PROTO_RZN1_A5PSW = DSA_TAG_PROTO_RZN1_A5PSW_VALUE,
		DSA_TAG_PROTO_LAN937X = DSA_TAG_PROTO_LAN937X_VALUE,
		DSA_TAG_PROTO_VSC73XX_8021Q = DSA_TAG_PROTO_VSC73XX_8021Q_VALUE,
		DSA_TAG_PROTO_YT921X = DSA_TAG_PROTO_YT921X_VALUE,
		};

		struct dsa_switch;

include/uapi/linux/if_ether.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -114,6 +114,7 @@
		#define ETH_P_QINQ1 0x9100 /* deprecated QinQ VLAN [ NOT AN OFFICIALLY REGISTERED ID ] */
		#define ETH_P_QINQ2 0x9200 /* deprecated QinQ VLAN [ NOT AN OFFICIALLY REGISTERED ID ] */
		#define ETH_P_QINQ3 0x9300 /* deprecated QinQ VLAN [ NOT AN OFFICIALLY REGISTERED ID ] */
		#define ETH_P_YT921X 0x9988 /* Motorcomm YT921x DSA [ NOT AN OFFICIALLY REGISTERED ID ] */
		#define ETH_P_EDSA 0xDADA /* Ethertype DSA [ NOT AN OFFICIALLY REGISTERED ID ] */
		#define ETH_P_DSA_8021Q 0xDADB /* Fake VLAN Header for DSA [ NOT AN OFFICIALLY REGISTERED ID ] */
		#define ETH_P_DSA_A5PSW 0xE001 /* A5PSW Tag Value [ NOT AN OFFICIALLY REGISTERED ID ] */

net/dsa/Kconfig

+6 −0

Original line number	Diff line number	Diff line
		@@ -190,4 +190,10 @@ config NET_DSA_TAG_XRS700X
		Say Y or M if you want to enable support for tagging frames for
		Arrow SpeedChips XRS700x switches that use a single byte tag trailer.

		config NET_DSA_TAG_YT921X
		tristate "Tag driver for Motorcomm YT921x switches"
		help
		Say Y or M if you want to enable support for tagging frames for
		Motorcomm YT921x switches.

		endif

net/dsa/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -39,6 +39,7 @@ obj-$(CONFIG_NET_DSA_TAG_SJA1105) += tag_sja1105.o
		obj-$(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

		# for tracing framework to find trace.h
		CFLAGS_trace.o := -I$(src)

net/dsa/tag_yt921x.c

0 → 100644

+141 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: GPL-2.0-or-later
		/*
		* Motorcomm YT921x Switch Extended CPU Port Tagging
		*
		* Copyright (c) 2025 David Yang <mmyangfl@gmail.com>
		*
		* +----+----+-------+-----+----+---------
		* \| DA \| SA \| TagET \| Tag \| ET \| Payload ...
		* +----+----+-------+-----+----+---------
		* 6 6 2 6 2 N
		*
		* Tag Ethertype: CPU_TAG_TPID_TPID (default: ETH_P_YT921X = 0x9988)
		* * Hardcoded for the moment, but still configurable. Discuss it if there
		* are conflicts somewhere and/or you want to change it for some reason.
		* Tag:
		* 2: VLAN Tag
		* 2: Rx Port
		* 15b: Rx Port Valid
		* 14b-11b: Rx Port
		* 10b-0b: Cmd?
		* 2: Tx Port(s)
		* 15b: Tx Port(s) Valid
		* 10b-0b: Tx Port(s) Mask
		*/

		#include <linux/etherdevice.h>

		#include "tag.h"

		#define YT921X_TAG_NAME "yt921x"

		#define YT921X_TAG_LEN 8

		#define YT921X_TAG_PORT_EN BIT(15)
		#define YT921X_TAG_RX_PORT_M GENMASK(14, 11)
		#define YT921X_TAG_RX_CMD_M GENMASK(10, 0)
		#define YT921X_TAG_RX_CMD(x) FIELD_PREP(YT921X_TAG_RX_CMD_M, (x))
		#define YT921X_TAG_RX_CMD_FORWARDED 0x80
		#define YT921X_TAG_RX_CMD_UNK_UCAST 0xb2
		#define YT921X_TAG_RX_CMD_UNK_MCAST 0xb4
		#define YT921X_TAG_TX_PORTS_M GENMASK(10, 0)
		#define YT921X_TAG_TX_PORTn(port) BIT(port)

		static struct sk_buff *
		yt921x_tag_xmit(struct sk_buff skb, struct net_device netdev)
		{
		struct dsa_port *dp = dsa_user_to_port(netdev);
		unsigned int port = dp->index;
		__be16 *tag;
		u16 tx;

		skb_push(skb, YT921X_TAG_LEN);
		dsa_alloc_etype_header(skb, YT921X_TAG_LEN);

		tag = dsa_etype_header_pos_tx(skb);

		tag[0] = htons(ETH_P_YT921X);
		/* VLAN tag unrelated when TX */
		tag[1] = 0;
		tag[2] = 0;
		tx = YT921X_TAG_PORT_EN \| YT921X_TAG_TX_PORTn(port);
		tag[3] = htons(tx);

		return skb;
		}

		static struct sk_buff *
		yt921x_tag_rcv(struct sk_buff skb, struct net_device netdev)
		{
		unsigned int port;
		__be16 *tag;
		u16 cmd;
		u16 rx;

		if (unlikely(!pskb_may_pull(skb, YT921X_TAG_LEN)))
		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]));
		return NULL;
		}

		/* Locate which port this is coming from */
		rx = ntohs(tag[2]);
		if (unlikely((rx & YT921X_TAG_PORT_EN) == 0)) {
		dev_warn_ratelimited(&netdev->dev,
		"Unexpected rx tag 0x%04x\n", rx);
		return NULL;
		}

		port = FIELD_GET(YT921X_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);
		return NULL;
		}

		cmd = FIELD_GET(YT921X_TAG_RX_CMD_M, rx);
		switch (cmd) {
		case YT921X_TAG_RX_CMD_FORWARDED:
		/* Already forwarded by hardware */
		dsa_default_offload_fwd_mark(skb);
		break;
		case YT921X_TAG_RX_CMD_UNK_UCAST:
		case YT921X_TAG_RX_CMD_UNK_MCAST:
		/* NOTE: hardware doesn't distinguish between TRAP (copy to CPU
		* only) and COPY (forward and copy to CPU). In order to perform
		* a soft switch, NEVER use COPY action in the switch driver.
		*/
		break;
		default:
		dev_warn_ratelimited(&netdev->dev,
		"Unexpected rx cmd 0x%02x\n", cmd);
		break;
		}

		/* Remove YT921x tag and update checksum */
		skb_pull_rcsum(skb, YT921X_TAG_LEN);
		dsa_strip_etype_header(skb, YT921X_TAG_LEN);

		return skb;
		}

		static const struct dsa_device_ops yt921x_netdev_ops = {
		.name = YT921X_TAG_NAME,
		.proto = DSA_TAG_PROTO_YT921X,
		.xmit = yt921x_tag_xmit,
		.rcv = yt921x_tag_rcv,
		.needed_headroom = YT921X_TAG_LEN,
		};

		MODULE_DESCRIPTION("DSA tag driver for Motorcomm YT921x switches");
		MODULE_LICENSE("GPL");
		MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_YT921X, YT921X_TAG_NAME);

		module_dsa_tag_driver(yt921x_netdev_ops);