net: dsa: add tag format for MxL862xx switches (85ee9874) · Commits · git / linux-net

MAINTAINERS

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		@@ -15631,6 +15631,7 @@ M: Daniel Golle <daniel@makrotopia.org>
		L: netdev@vger.kernel.org
		S: Maintained
		F: Documentation/devicetree/bindings/net/dsa/maxlinear,mxl862xx.yaml
		F: net/dsa/tag_mxl862xx.c

		MCAN DEVICE DRIVER
		M: Markus Schneider-Pargmann <msp@baylibre.com>

include/net/dsa.h

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		@@ -57,6 +57,7 @@ struct tc_action;
		#define DSA_TAG_PROTO_BRCM_LEGACY_FCS_VALUE 29
		#define DSA_TAG_PROTO_YT921X_VALUE 30
		#define DSA_TAG_PROTO_MXL_GSW1XX_VALUE 31
		#define DSA_TAG_PROTO_MXL862_VALUE 32

		enum dsa_tag_protocol {
		DSA_TAG_PROTO_NONE = DSA_TAG_PROTO_NONE_VALUE,
		@@ -91,6 +92,7 @@ enum dsa_tag_protocol {
		DSA_TAG_PROTO_VSC73XX_8021Q = DSA_TAG_PROTO_VSC73XX_8021Q_VALUE,
		DSA_TAG_PROTO_YT921X = DSA_TAG_PROTO_YT921X_VALUE,
		DSA_TAG_PROTO_MXL_GSW1XX = DSA_TAG_PROTO_MXL_GSW1XX_VALUE,
		DSA_TAG_PROTO_MXL862 = DSA_TAG_PROTO_MXL862_VALUE,
		};

		struct dsa_switch;

net/dsa/Kconfig

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		@@ -104,6 +104,13 @@ config NET_DSA_TAG_MTK
		Say Y or M if you want to enable support for tagging frames for
		Mediatek switches.

		config NET_DSA_TAG_MXL_862XX
		tristate "Tag driver for MaxLinear MxL862xx switches"
		help
		Say Y or M if you want to enable support for tagging frames for the
		MaxLinear MxL86252 and MxL86282 switches using their native 8-byte
		tagging protocol.

		config NET_DSA_TAG_MXL_GSW1XX
		tristate "Tag driver for MaxLinear GSW1xx switches"
		help

net/dsa/Makefile

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		@@ -28,6 +28,7 @@ obj-$(CONFIG_NET_DSA_TAG_HELLCREEK) += tag_hellcreek.o
		obj-$(CONFIG_NET_DSA_TAG_KSZ) += tag_ksz.o
		obj-$(CONFIG_NET_DSA_TAG_LAN9303) += tag_lan9303.o
		obj-$(CONFIG_NET_DSA_TAG_MTK) += tag_mtk.o
		obj-$(CONFIG_NET_DSA_TAG_MXL_862XX) += tag_mxl862xx.o
		obj-$(CONFIG_NET_DSA_TAG_MXL_GSW1XX) += tag_mxl-gsw1xx.o
		obj-$(CONFIG_NET_DSA_TAG_NONE) += tag_none.o
		obj-$(CONFIG_NET_DSA_TAG_OCELOT) += tag_ocelot.o

net/dsa/tag_mxl862xx.c

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		// SPDX-License-Identifier: GPL-2.0-or-later
		/*
		* DSA Special Tag for MaxLinear 862xx switch chips
		*
		* Copyright (C) 2025 Daniel Golle <daniel@makrotopia.org>
		* Copyright (C) 2024 MaxLinear Inc.
		*/

		#include <linux/bitops.h>
		#include <linux/etherdevice.h>
		#include <linux/skbuff.h>
		#include <net/dsa.h>
		#include "tag.h"

		#define MXL862_NAME "mxl862xx"

		#define MXL862_HEADER_LEN 8

		/* Word 0 -> EtherType */

		/* Word 2 */
		#define MXL862_SUBIF_ID GENMASK(4, 0)

		/* Word 3 */
		#define MXL862_IGP_EGP GENMASK(3, 0)

		static struct sk_buff mxl862_tag_xmit(struct sk_buff skb,
		struct net_device *dev)
		{
		struct dsa_port *dp = dsa_user_to_port(dev);
		struct dsa_port *cpu_dp = dp->cpu_dp;
		unsigned int cpu_port, sub_interface;
		__be16 *mxl862_tag;

		cpu_port = cpu_dp->index;

		/* target port sub-interface ID relative to the CPU port */
		sub_interface = dp->index + 16 - cpu_port;

		/* provide additional space 'MXL862_HEADER_LEN' bytes */
		skb_push(skb, MXL862_HEADER_LEN);

		/* shift MAC address to the beginning of the enlarged buffer,
		* releasing the space required for DSA tag (between MAC address and
		* Ethertype)
		*/
		dsa_alloc_etype_header(skb, MXL862_HEADER_LEN);

		/* special tag ingress (from the perspective of the switch) */
		mxl862_tag = dsa_etype_header_pos_tx(skb);
		mxl862_tag[0] = htons(ETH_P_MXLGSW);
		mxl862_tag[1] = 0;
		mxl862_tag[2] = htons(FIELD_PREP(MXL862_SUBIF_ID, sub_interface));
		mxl862_tag[3] = htons(FIELD_PREP(MXL862_IGP_EGP, cpu_port));

		return skb;
		}

		static struct sk_buff mxl862_tag_rcv(struct sk_buff skb,
		struct net_device *dev)
		{
		__be16 *mxl862_tag;
		int port;

		if (unlikely(!pskb_may_pull(skb, MXL862_HEADER_LEN))) {
		dev_warn_ratelimited(&dev->dev, "Cannot pull SKB, packet dropped\n");
		return NULL;
		}

		mxl862_tag = dsa_etype_header_pos_rx(skb);

		if (unlikely(mxl862_tag[0] != htons(ETH_P_MXLGSW))) {
		dev_warn_ratelimited(&dev->dev,
		"Invalid special tag marker, packet dropped, tag: %8ph\n",
		mxl862_tag);
		return NULL;
		}

		/* Get source port information */
		port = FIELD_GET(MXL862_IGP_EGP, ntohs(mxl862_tag[3]));
		skb->dev = dsa_conduit_find_user(dev, 0, port);
		if (unlikely(!skb->dev)) {
		dev_warn_ratelimited(&dev->dev,
		"Invalid source port, packet dropped, tag: %8ph\n",
		mxl862_tag);
		return NULL;
		}

		/* remove the MxL862xx special tag between the MAC addresses and the
		* current ethertype field.
		*/
		skb_pull_rcsum(skb, MXL862_HEADER_LEN);
		dsa_strip_etype_header(skb, MXL862_HEADER_LEN);

		return skb;
		}

		static const struct dsa_device_ops mxl862_netdev_ops = {
		.name = MXL862_NAME,
		.proto = DSA_TAG_PROTO_MXL862,
		.xmit = mxl862_tag_xmit,
		.rcv = mxl862_tag_rcv,
		.needed_headroom = MXL862_HEADER_LEN,
		};

		MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_MXL862, MXL862_NAME);
		MODULE_DESCRIPTION("DSA tag driver for MaxLinear MxL862xx switches");
		MODULE_LICENSE("GPL");

		module_dsa_tag_driver(mxl862_netdev_ops);