net: dsa: tag_dsa: Unify regular and ethertype DSA taggers

Ethertype DSA encodes exactly the same information in the DSA tag as
the non-ethertype variety. So refactor out the common parts and reuse
them for both protocols.

This is ensures tag parsing and generation is always consistent across
all mv88e6xxx chips.

While we are at it, explicitly deal with all possible CPU codes on
receive, making sure to set offload_fwd_mark as appropriate.
Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/dsa/Kconfig

@@ -68,14 +68,19 @@ config NET_DSA_TAG_GSWIP
 	  Say Y or M if you want to enable support for tagging frames for the
 	  Lantiq / Intel GSWIP switches.
 
+config NET_DSA_TAG_DSA_COMMON
+	tristate
+
 config NET_DSA_TAG_DSA
 	tristate "Tag driver for Marvell switches using DSA headers"
+	select NET_DSA_TAG_DSA_COMMON
 	help
 	  Say Y or M if you want to enable support for tagging frames for the
 	  Marvell switches which use DSA headers.
 
 config NET_DSA_TAG_EDSA
 	tristate "Tag driver for Marvell switches using EtherType DSA headers"
+	select NET_DSA_TAG_DSA_COMMON
 	help
 	  Say Y or M if you want to enable support for tagging frames for the
 	  Marvell switches which use EtherType DSA headers.

net/dsa/Makefile

@@ -7,8 +7,7 @@ dsa_core-y += dsa.o dsa2.o master.o port.o slave.o switch.o
 obj-$(CONFIG_NET_DSA_TAG_8021Q) += tag_8021q.o
 obj-$(CONFIG_NET_DSA_TAG_AR9331) += tag_ar9331.o
 obj-$(CONFIG_NET_DSA_TAG_BRCM_COMMON) += tag_brcm.o
-obj-$(CONFIG_NET_DSA_TAG_DSA) += tag_dsa.o
-obj-$(CONFIG_NET_DSA_TAG_EDSA) += tag_edsa.o
+obj-$(CONFIG_NET_DSA_TAG_DSA_COMMON) += tag_dsa.o
 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

net/dsa/tag_edsa.c

-// SPDX-License-Identifier: GPL-2.0+
-/*
- * net/dsa/tag_edsa.c - Ethertype DSA tagging
- * Copyright (c) 2008-2009 Marvell Semiconductor
- */
-
-#include <linux/etherdevice.h>
-#include <linux/list.h>
-#include <linux/slab.h>
-
-#include "dsa_priv.h"
-
-#define DSA_HLEN	4
-#define EDSA_HLEN	8
-
-#define FRAME_TYPE_TO_CPU	0x00
-#define FRAME_TYPE_FORWARD	0x03
-
-#define TO_CPU_CODE_MGMT_TRAP		0x00
-#define TO_CPU_CODE_FRAME2REG		0x01
-#define TO_CPU_CODE_IGMP_MLD_TRAP	0x02
-#define TO_CPU_CODE_POLICY_TRAP		0x03
-#define TO_CPU_CODE_ARP_MIRROR		0x04
-#define TO_CPU_CODE_POLICY_MIRROR	0x05
-
-static struct sk_buff *edsa_xmit(struct sk_buff *skb, struct net_device *dev)
-{
-	struct dsa_port *dp = dsa_slave_to_port(dev);
-	u8 *edsa_header;
-
-	/*
-	 * Convert the outermost 802.1q tag to a DSA tag and prepend
-	 * a DSA ethertype field is the packet is tagged, or insert
-	 * a DSA ethertype plus DSA tag between the addresses and the
-	 * current ethertype field if the packet is untagged.
-	 */
-	if (skb->protocol == htons(ETH_P_8021Q)) {
-		skb_push(skb, DSA_HLEN);
-
-		memmove(skb->data, skb->data + DSA_HLEN, 2 * ETH_ALEN);
-
-		/*
-		 * Construct tagged FROM_CPU DSA tag from 802.1q tag.
-		 */
-		edsa_header = skb->data + 2 * ETH_ALEN;
-		edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
-		edsa_header[1] = ETH_P_EDSA & 0xff;
-		edsa_header[2] = 0x00;
-		edsa_header[3] = 0x00;
-		edsa_header[4] = 0x60 | dp->ds->index;
-		edsa_header[5] = dp->index << 3;
-
-		/*
-		 * Move CFI field from byte 6 to byte 5.
-		 */
-		if (edsa_header[6] & 0x10) {
-			edsa_header[5] |= 0x01;
-			edsa_header[6] &= ~0x10;
-		}
-	} else {
-		skb_push(skb, EDSA_HLEN);
-
-		memmove(skb->data, skb->data + EDSA_HLEN, 2 * ETH_ALEN);
-
-		/*
-		 * Construct untagged FROM_CPU DSA tag.
-		 */
-		edsa_header = skb->data + 2 * ETH_ALEN;
-		edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
-		edsa_header[1] = ETH_P_EDSA & 0xff;
-		edsa_header[2] = 0x00;
-		edsa_header[3] = 0x00;
-		edsa_header[4] = 0x40 | dp->ds->index;
-		edsa_header[5] = dp->index << 3;
-		edsa_header[6] = 0x00;
-		edsa_header[7] = 0x00;
-	}
-
-	return skb;
-}
-
-static struct sk_buff *edsa_rcv(struct sk_buff *skb, struct net_device *dev,
-				struct packet_type *pt)
-{
-	u8 *edsa_header;
-	int frame_type;
-	int code;
-	int source_device;
-	int source_port;
-
-	if (unlikely(!pskb_may_pull(skb, EDSA_HLEN)))
-		return NULL;
-
-	/*
-	 * Skip the two null bytes after the ethertype.
-	 */
-	edsa_header = skb->data + 2;
-
-	/*
-	 * Check that frame type is either TO_CPU or FORWARD.
-	 */
-	frame_type = edsa_header[0] >> 6;
-
-	switch (frame_type) {
-	case FRAME_TYPE_TO_CPU:
-		code = (edsa_header[1] & 0x6) | ((edsa_header[2] >> 4) & 1);
-
-		/*
-		 * Mark the frame to never egress on any port of the same switch
-		 * unless it's a trapped IGMP/MLD packet, in which case the
-		 * bridge might want to forward it.
-		 */
-		if (code != TO_CPU_CODE_IGMP_MLD_TRAP)
-			skb->offload_fwd_mark = 1;
-
-		break;
-
-	case FRAME_TYPE_FORWARD:
-		skb->offload_fwd_mark = 1;
-		break;
-
-	default:
-		return NULL;
-	}
-
-	/*
-	 * Determine source device and port.
-	 */
-	source_device = edsa_header[0] & 0x1f;
-	source_port = (edsa_header[1] >> 3) & 0x1f;
-
-	skb->dev = dsa_master_find_slave(dev, source_device, source_port);
-	if (!skb->dev)
-		return NULL;
-
-	/*
-	 * If the 'tagged' bit is set, convert the DSA tag to a 802.1q
-	 * tag and delete the ethertype part.  If the 'tagged' bit is
-	 * clear, delete the ethertype and the DSA tag parts.
-	 */
-	if (edsa_header[0] & 0x20) {
-		u8 new_header[4];
-
-		/*
-		 * Insert 802.1q ethertype and copy the VLAN-related
-		 * fields, but clear the bit that will hold CFI (since
-		 * DSA uses that bit location for another purpose).
-		 */
-		new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
-		new_header[1] = ETH_P_8021Q & 0xff;
-		new_header[2] = edsa_header[2] & ~0x10;
-		new_header[3] = edsa_header[3];
-
-		/*
-		 * Move CFI bit from its place in the DSA header to
-		 * its 802.1q-designated place.
-		 */
-		if (edsa_header[1] & 0x01)
-			new_header[2] |= 0x10;
-
-		skb_pull_rcsum(skb, DSA_HLEN);
-
-		/*
-		 * Update packet checksum if skb is CHECKSUM_COMPLETE.
-		 */
-		if (skb->ip_summed == CHECKSUM_COMPLETE) {
-			__wsum c = skb->csum;
-			c = csum_add(c, csum_partial(new_header + 2, 2, 0));
-			c = csum_sub(c, csum_partial(edsa_header + 2, 2, 0));
-			skb->csum = c;
-		}
-
-		memcpy(edsa_header, new_header, DSA_HLEN);
-
-		memmove(skb->data - ETH_HLEN,
-			skb->data - ETH_HLEN - DSA_HLEN,
-			2 * ETH_ALEN);
-	} else {
-		/*
-		 * Remove DSA tag and update checksum.
-		 */
-		skb_pull_rcsum(skb, EDSA_HLEN);
-		memmove(skb->data - ETH_HLEN,
-			skb->data - ETH_HLEN - EDSA_HLEN,
-			2 * ETH_ALEN);
-	}
-
-	return skb;
-}
-
-static const struct dsa_device_ops edsa_netdev_ops = {
-	.name	= "edsa",
-	.proto	= DSA_TAG_PROTO_EDSA,
-	.xmit	= edsa_xmit,
-	.rcv	= edsa_rcv,
-	.overhead = EDSA_HLEN,
-};
-
-MODULE_LICENSE("GPL");
-MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_EDSA);
-
-module_dsa_tag_driver(edsa_netdev_ops);