1 // SPDX-License-Identifier: GPL-2.0+
3 * Regular and Ethertype DSA tagging
4 * Copyright (c) 2008-2009 Marvell Semiconductor
9 * For untagged (in 802.1Q terms) packets, the switch will splice in
10 * the tag between the SA and the ethertype of the original
11 * packet. Tagged frames will instead have their outermost .1Q tag
12 * converted to a DSA tag. It expects the same layout when receiving
13 * packets from the CPU.
17 * .----.----.----.---------
18 * Pu: | DA | SA | ET | Payload ...
19 * '----'----'----'---------
21 * .----.----.--------.-----.----.---------
22 * Pt: | DA | SA | 0x8100 | TCI | ET | Payload ...
23 * '----'----'--------'-----'----'---------
25 * .----.----.-----.----.---------
26 * Pd: | DA | SA | DSA | ET | Payload ...
27 * '----'----'-----'----'---------
30 * No matter if a packet is received untagged (Pu) or tagged (Pt),
31 * they will both have the same layout (Pd) when they are sent to the
32 * CPU. This is done by ignoring 802.3, replacing the ethertype field
33 * with more metadata, among which is a bit to signal if the original
34 * packet was tagged or not.
38 * Uses the exact same tag format as regular DSA, but also includes a
39 * proper ethertype field (which the mv88e6xxx driver sets to
40 * ETH_P_EDSA/0xdada) followed by two zero bytes:
42 * .----.----.--------.--------.-----.----.---------
43 * | DA | SA | 0xdada | 0x0000 | DSA | ET | Payload ...
44 * '----'----'--------'--------'-----'----'---------
48 #include <linux/dsa/mv88e6xxx.h>
49 #include <linux/etherdevice.h>
50 #include <linux/list.h>
51 #include <linux/slab.h>
58 * enum dsa_cmd - DSA Command
59 * @DSA_CMD_TO_CPU: Set on packets that were trapped or mirrored to
60 * the CPU port. This is needed to implement control protocols,
61 * e.g. STP and LLDP, that must not allow those control packets to
62 * be switched according to the normal rules.
63 * @DSA_CMD_FROM_CPU: Used by the CPU to send a packet to a specific
64 * port, ignoring all the barriers that the switch normally
65 * enforces (VLANs, STP port states etc.). No source address
66 * learning takes place. "sudo send packet"
67 * @DSA_CMD_TO_SNIFFER: Set on the copies of packets that matched some
68 * user configured ingress or egress monitor criteria. These are
69 * forwarded by the switch tree to the user configured ingress or
70 * egress monitor port, which can be set to the CPU port or a
71 * regular port. If the destination is a regular port, the tag
72 * will be removed before egressing the port. If the destination
73 * is the CPU port, the tag will not be removed.
74 * @DSA_CMD_FORWARD: This tag is used on all bulk traffic passing
75 * through the switch tree, including the flows that are directed
76 * towards the CPU. Its device/port tuple encodes the original
77 * source port on which the packet ingressed. It can also be used
78 * on transmit by the CPU to defer the forwarding decision to the
79 * hardware, based on the current config of PVT/VTU/ATU
80 * etc. Source address learning takes places if enabled on the
81 * receiving DSA/CPU port.
86 DSA_CMD_TO_SNIFFER = 2,
91 * enum dsa_code - TO_CPU Code
93 * @DSA_CODE_MGMT_TRAP: DA was classified as a management
94 * address. Typical examples include STP BPDUs and LLDP.
95 * @DSA_CODE_FRAME2REG: Response to a "remote management" request.
96 * @DSA_CODE_IGMP_MLD_TRAP: IGMP/MLD signaling.
97 * @DSA_CODE_POLICY_TRAP: Frame matched some policy configuration on
98 * the device. Typical examples are matching on DA/SA/VID and DHCP
100 * @DSA_CODE_ARP_MIRROR: The name says it all really.
101 * @DSA_CODE_POLICY_MIRROR: Same as @DSA_CODE_POLICY_TRAP, but the
102 * particular policy was set to trigger a mirror instead of a
104 * @DSA_CODE_RESERVED_6: Unused on all devices up to at least 6393X.
105 * @DSA_CODE_RESERVED_7: Unused on all devices up to at least 6393X.
107 * A 3-bit code is used to relay why a particular frame was sent to
108 * the CPU. We only use this to determine if the packet was mirrored
109 * or trapped, i.e. whether the packet has been forwarded by hardware
112 * This is the superset of all possible codes. Any particular device
113 * may only implement a subset.
116 DSA_CODE_MGMT_TRAP = 0,
117 DSA_CODE_FRAME2REG = 1,
118 DSA_CODE_IGMP_MLD_TRAP = 2,
119 DSA_CODE_POLICY_TRAP = 3,
120 DSA_CODE_ARP_MIRROR = 4,
121 DSA_CODE_POLICY_MIRROR = 5,
122 DSA_CODE_RESERVED_6 = 6,
123 DSA_CODE_RESERVED_7 = 7
126 static struct sk_buff *dsa_xmit_ll(struct sk_buff *skb, struct net_device *dev,
129 struct dsa_port *dp = dsa_slave_to_port(dev);
130 u8 tag_dev, tag_port;
134 if (skb->offload_fwd_mark) {
135 unsigned int bridge_num = dsa_port_bridge_num_get(dp);
136 struct dsa_switch_tree *dst = dp->ds->dst;
138 cmd = DSA_CMD_FORWARD;
140 /* When offloading forwarding for a bridge, inject FORWARD
141 * packets on behalf of a virtual switch device with an index
142 * past the physical switches.
144 tag_dev = dst->last_switch + bridge_num;
147 cmd = DSA_CMD_FROM_CPU;
148 tag_dev = dp->ds->index;
149 tag_port = dp->index;
152 if (skb->protocol == htons(ETH_P_8021Q)) {
154 skb_push(skb, extra);
155 dsa_alloc_etype_header(skb, extra);
158 /* Construct tagged DSA tag from 802.1Q tag. */
159 dsa_header = dsa_etype_header_pos_tx(skb) + extra;
160 dsa_header[0] = (cmd << 6) | 0x20 | tag_dev;
161 dsa_header[1] = tag_port << 3;
163 /* Move CFI field from byte 2 to byte 1. */
164 if (dsa_header[2] & 0x10) {
165 dsa_header[1] |= 0x01;
166 dsa_header[2] &= ~0x10;
169 struct net_device *br = dsa_port_bridge_dev_get(dp);
172 vid = br ? MV88E6XXX_VID_BRIDGED : MV88E6XXX_VID_STANDALONE;
174 skb_push(skb, DSA_HLEN + extra);
175 dsa_alloc_etype_header(skb, DSA_HLEN + extra);
177 /* Construct DSA header from untagged frame. */
178 dsa_header = dsa_etype_header_pos_tx(skb) + extra;
180 dsa_header[0] = (cmd << 6) | tag_dev;
181 dsa_header[1] = tag_port << 3;
182 dsa_header[2] = vid >> 8;
183 dsa_header[3] = vid & 0xff;
189 static struct sk_buff *dsa_rcv_ll(struct sk_buff *skb, struct net_device *dev,
192 bool trap = false, trunk = false;
193 int source_device, source_port;
198 /* The ethertype field is part of the DSA header. */
199 dsa_header = dsa_etype_header_pos_rx(skb);
201 cmd = dsa_header[0] >> 6;
203 case DSA_CMD_FORWARD:
204 trunk = !!(dsa_header[1] & 4);
208 code = (dsa_header[1] & 0x6) | ((dsa_header[2] >> 4) & 1);
211 case DSA_CODE_FRAME2REG:
212 /* Remote management is not implemented yet,
216 case DSA_CODE_ARP_MIRROR:
217 case DSA_CODE_POLICY_MIRROR:
218 /* Mark mirrored packets to notify any upper
219 * device (like a bridge) that forwarding has
220 * already been done by hardware.
223 case DSA_CODE_MGMT_TRAP:
224 case DSA_CODE_IGMP_MLD_TRAP:
225 case DSA_CODE_POLICY_TRAP:
226 /* Traps have, by definition, not been
227 * forwarded by hardware, so don't mark them.
232 /* Reserved code, this could be anything. Drop
233 * seems like the safest option.
244 source_device = dsa_header[0] & 0x1f;
245 source_port = (dsa_header[1] >> 3) & 0x1f;
248 struct dsa_port *cpu_dp = dev->dsa_ptr;
250 /* The exact source port is not available in the tag,
251 * so we inject the frame directly on the upper
254 skb->dev = dsa_lag_dev(cpu_dp->dst, source_port);
256 skb->dev = dsa_master_find_slave(dev, source_device,
263 /* When using LAG offload, skb->dev is not a DSA slave interface,
264 * so we cannot call dsa_default_offload_fwd_mark and we need to
268 skb->offload_fwd_mark = true;
270 dsa_default_offload_fwd_mark(skb);
272 /* If the 'tagged' bit is set; convert the DSA tag to a 802.1Q
273 * tag, and delete the ethertype (extra) if applicable. If the
274 * 'tagged' bit is cleared; delete the DSA tag, and ethertype
277 if (dsa_header[0] & 0x20) {
280 /* Insert 802.1Q ethertype and copy the VLAN-related
281 * fields, but clear the bit that will hold CFI (since
282 * DSA uses that bit location for another purpose).
284 new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
285 new_header[1] = ETH_P_8021Q & 0xff;
286 new_header[2] = dsa_header[2] & ~0x10;
287 new_header[3] = dsa_header[3];
289 /* Move CFI bit from its place in the DSA header to
290 * its 802.1Q-designated place.
292 if (dsa_header[1] & 0x01)
293 new_header[2] |= 0x10;
295 /* Update packet checksum if skb is CHECKSUM_COMPLETE. */
296 if (skb->ip_summed == CHECKSUM_COMPLETE) {
297 __wsum c = skb->csum;
298 c = csum_add(c, csum_partial(new_header + 2, 2, 0));
299 c = csum_sub(c, csum_partial(dsa_header + 2, 2, 0));
303 memcpy(dsa_header, new_header, DSA_HLEN);
306 dsa_strip_etype_header(skb, extra);
308 skb_pull_rcsum(skb, DSA_HLEN);
309 dsa_strip_etype_header(skb, DSA_HLEN + extra);
315 #if IS_ENABLED(CONFIG_NET_DSA_TAG_DSA)
317 static struct sk_buff *dsa_xmit(struct sk_buff *skb, struct net_device *dev)
319 return dsa_xmit_ll(skb, dev, 0);
322 static struct sk_buff *dsa_rcv(struct sk_buff *skb, struct net_device *dev)
324 if (unlikely(!pskb_may_pull(skb, DSA_HLEN)))
327 return dsa_rcv_ll(skb, dev, 0);
330 static const struct dsa_device_ops dsa_netdev_ops = {
332 .proto = DSA_TAG_PROTO_DSA,
335 .needed_headroom = DSA_HLEN,
338 DSA_TAG_DRIVER(dsa_netdev_ops);
339 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_DSA);
340 #endif /* CONFIG_NET_DSA_TAG_DSA */
342 #if IS_ENABLED(CONFIG_NET_DSA_TAG_EDSA)
346 static struct sk_buff *edsa_xmit(struct sk_buff *skb, struct net_device *dev)
350 skb = dsa_xmit_ll(skb, dev, EDSA_HLEN - DSA_HLEN);
354 edsa_header = dsa_etype_header_pos_tx(skb);
355 edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
356 edsa_header[1] = ETH_P_EDSA & 0xff;
357 edsa_header[2] = 0x00;
358 edsa_header[3] = 0x00;
362 static struct sk_buff *edsa_rcv(struct sk_buff *skb, struct net_device *dev)
364 if (unlikely(!pskb_may_pull(skb, EDSA_HLEN)))
367 skb_pull_rcsum(skb, EDSA_HLEN - DSA_HLEN);
369 return dsa_rcv_ll(skb, dev, EDSA_HLEN - DSA_HLEN);
372 static const struct dsa_device_ops edsa_netdev_ops = {
374 .proto = DSA_TAG_PROTO_EDSA,
377 .needed_headroom = EDSA_HLEN,
380 DSA_TAG_DRIVER(edsa_netdev_ops);
381 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_EDSA);
382 #endif /* CONFIG_NET_DSA_TAG_EDSA */
384 static struct dsa_tag_driver *dsa_tag_drivers[] = {
385 #if IS_ENABLED(CONFIG_NET_DSA_TAG_DSA)
386 &DSA_TAG_DRIVER_NAME(dsa_netdev_ops),
388 #if IS_ENABLED(CONFIG_NET_DSA_TAG_EDSA)
389 &DSA_TAG_DRIVER_NAME(edsa_netdev_ops),
393 module_dsa_tag_drivers(dsa_tag_drivers);
395 MODULE_LICENSE("GPL");