1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Broadcom tag support
4 *
5 * Copyright (C) 2014 Broadcom Corporation
6 */
7
8 #include <linux/dsa/brcm.h>
9 #include <linux/etherdevice.h>
10 #include <linux/list.h>
11 #include <linux/slab.h>
12
13 #include "dsa_priv.h"
14
15 /* Legacy Broadcom tag (6 bytes) */
16 #define BRCM_LEG_TAG_LEN 6
17
18 /* Type fields */
19 /* 1st byte in the tag */
20 #define BRCM_LEG_TYPE_HI 0x88
21 /* 2nd byte in the tag */
22 #define BRCM_LEG_TYPE_LO 0x74
23
24 /* Tag fields */
25 /* 3rd byte in the tag */
26 #define BRCM_LEG_UNICAST (0 << 5)
27 #define BRCM_LEG_MULTICAST (1 << 5)
28 #define BRCM_LEG_EGRESS (2 << 5)
29 #define BRCM_LEG_INGRESS (3 << 5)
30
31 /* 6th byte in the tag */
32 #define BRCM_LEG_PORT_ID (0xf)
33
34 /* Newer Broadcom tag (4 bytes) */
35 #define BRCM_TAG_LEN 4
36
37 /* Tag is constructed and desconstructed using byte by byte access
38 * because the tag is placed after the MAC Source Address, which does
39 * not make it 4-bytes aligned, so this might cause unaligned accesses
40 * on most systems where this is used.
41 */
42
43 /* Ingress and egress opcodes */
44 #define BRCM_OPCODE_SHIFT 5
45 #define BRCM_OPCODE_MASK 0x7
46
47 /* Ingress fields */
48 /* 1st byte in the tag */
49 #define BRCM_IG_TC_SHIFT 2
50 #define BRCM_IG_TC_MASK 0x7
51 /* 2nd byte in the tag */
52 #define BRCM_IG_TE_MASK 0x3
53 #define BRCM_IG_TS_SHIFT 7
54 /* 3rd byte in the tag */
55 #define BRCM_IG_DSTMAP2_MASK 1
56 #define BRCM_IG_DSTMAP1_MASK 0xff
57
58 /* Egress fields */
59
60 /* 2nd byte in the tag */
61 #define BRCM_EG_CID_MASK 0xff
62
63 /* 3rd byte in the tag */
64 #define BRCM_EG_RC_MASK 0xff
65 #define BRCM_EG_RC_RSVD (3 << 6)
66 #define BRCM_EG_RC_EXCEPTION (1 << 5)
67 #define BRCM_EG_RC_PROT_SNOOP (1 << 4)
68 #define BRCM_EG_RC_PROT_TERM (1 << 3)
69 #define BRCM_EG_RC_SWITCH (1 << 2)
70 #define BRCM_EG_RC_MAC_LEARN (1 << 1)
71 #define BRCM_EG_RC_MIRROR (1 << 0)
72 #define BRCM_EG_TC_SHIFT 5
73 #define BRCM_EG_TC_MASK 0x7
74 #define BRCM_EG_PID_MASK 0x1f
75
76 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM) || \
77 IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
78
brcm_tag_xmit_ll(struct sk_buff * skb,struct net_device * dev,unsigned int offset)79 static struct sk_buff *brcm_tag_xmit_ll(struct sk_buff *skb,
80 struct net_device *dev,
81 unsigned int offset)
82 {
83 struct dsa_port *dp = dsa_slave_to_port(dev);
84 u16 queue = skb_get_queue_mapping(skb);
85 u8 *brcm_tag;
86
87 /* The Ethernet switch we are interfaced with needs packets to be at
88 * least 64 bytes (including FCS) otherwise they will be discarded when
89 * they enter the switch port logic. When Broadcom tags are enabled, we
90 * need to make sure that packets are at least 68 bytes
91 * (including FCS and tag) because the length verification is done after
92 * the Broadcom tag is stripped off the ingress packet.
93 *
94 * Let dsa_slave_xmit() free the SKB
95 */
96 if (__skb_put_padto(skb, ETH_ZLEN + BRCM_TAG_LEN, false))
97 return NULL;
98
99 skb_push(skb, BRCM_TAG_LEN);
100
101 if (offset)
102 memmove(skb->data, skb->data + BRCM_TAG_LEN, offset);
103
104 brcm_tag = skb->data + offset;
105
106 /* Set the ingress opcode, traffic class, tag enforcment is
107 * deprecated
108 */
109 brcm_tag[0] = (1 << BRCM_OPCODE_SHIFT) |
110 ((queue & BRCM_IG_TC_MASK) << BRCM_IG_TC_SHIFT);
111 brcm_tag[1] = 0;
112 brcm_tag[2] = 0;
113 if (dp->index == 8)
114 brcm_tag[2] = BRCM_IG_DSTMAP2_MASK;
115 brcm_tag[3] = (1 << dp->index) & BRCM_IG_DSTMAP1_MASK;
116
117 /* Now tell the master network device about the desired output queue
118 * as well
119 */
120 skb_set_queue_mapping(skb, BRCM_TAG_SET_PORT_QUEUE(dp->index, queue));
121
122 return skb;
123 }
124
125 /* Frames with this tag have one of these two layouts:
126 * -----------------------------------
127 * | MAC DA | MAC SA | 4b tag | Type | DSA_TAG_PROTO_BRCM
128 * -----------------------------------
129 * -----------------------------------
130 * | 4b tag | MAC DA | MAC SA | Type | DSA_TAG_PROTO_BRCM_PREPEND
131 * -----------------------------------
132 * In both cases, at receive time, skb->data points 2 bytes before the actual
133 * Ethernet type field and we have an offset of 4bytes between where skb->data
134 * and where the payload starts. So the same low-level receive function can be
135 * used.
136 */
brcm_tag_rcv_ll(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt,unsigned int offset)137 static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,
138 struct net_device *dev,
139 struct packet_type *pt,
140 unsigned int offset)
141 {
142 int source_port;
143 u8 *brcm_tag;
144
145 if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN)))
146 return NULL;
147
148 brcm_tag = skb->data - offset;
149
150 /* The opcode should never be different than 0b000 */
151 if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK))
152 return NULL;
153
154 /* We should never see a reserved reason code without knowing how to
155 * handle it
156 */
157 if (unlikely(brcm_tag[2] & BRCM_EG_RC_RSVD))
158 return NULL;
159
160 /* Locate which port this is coming from */
161 source_port = brcm_tag[3] & BRCM_EG_PID_MASK;
162
163 skb->dev = dsa_master_find_slave(dev, 0, source_port);
164 if (!skb->dev)
165 return NULL;
166
167 /* Remove Broadcom tag and update checksum */
168 skb_pull_rcsum(skb, BRCM_TAG_LEN);
169
170 skb->offload_fwd_mark = 1;
171
172 return skb;
173 }
174 #endif
175
176 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM)
brcm_tag_xmit(struct sk_buff * skb,struct net_device * dev)177 static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb,
178 struct net_device *dev)
179 {
180 /* Build the tag after the MAC Source Address */
181 return brcm_tag_xmit_ll(skb, dev, 2 * ETH_ALEN);
182 }
183
184
brcm_tag_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt)185 static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev,
186 struct packet_type *pt)
187 {
188 struct sk_buff *nskb;
189
190 /* skb->data points to the EtherType, the tag is right before it */
191 nskb = brcm_tag_rcv_ll(skb, dev, pt, 2);
192 if (!nskb)
193 return nskb;
194
195 /* Move the Ethernet DA and SA */
196 memmove(nskb->data - ETH_HLEN,
197 nskb->data - ETH_HLEN - BRCM_TAG_LEN,
198 2 * ETH_ALEN);
199
200 return nskb;
201 }
202
203 static const struct dsa_device_ops brcm_netdev_ops = {
204 .name = "brcm",
205 .proto = DSA_TAG_PROTO_BRCM,
206 .xmit = brcm_tag_xmit,
207 .rcv = brcm_tag_rcv,
208 .overhead = BRCM_TAG_LEN,
209 };
210
211 DSA_TAG_DRIVER(brcm_netdev_ops);
212 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM);
213 #endif
214
215 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_LEGACY)
brcm_leg_tag_xmit(struct sk_buff * skb,struct net_device * dev)216 static struct sk_buff *brcm_leg_tag_xmit(struct sk_buff *skb,
217 struct net_device *dev)
218 {
219 struct dsa_port *dp = dsa_slave_to_port(dev);
220 u8 *brcm_tag;
221
222 /* The Ethernet switch we are interfaced with needs packets to be at
223 * least 64 bytes (including FCS) otherwise they will be discarded when
224 * they enter the switch port logic. When Broadcom tags are enabled, we
225 * need to make sure that packets are at least 70 bytes
226 * (including FCS and tag) because the length verification is done after
227 * the Broadcom tag is stripped off the ingress packet.
228 *
229 * Let dsa_slave_xmit() free the SKB
230 */
231 if (__skb_put_padto(skb, ETH_ZLEN + BRCM_LEG_TAG_LEN, false))
232 return NULL;
233
234 skb_push(skb, BRCM_LEG_TAG_LEN);
235
236 memmove(skb->data, skb->data + BRCM_LEG_TAG_LEN, 2 * ETH_ALEN);
237
238 brcm_tag = skb->data + 2 * ETH_ALEN;
239
240 /* Broadcom tag type */
241 brcm_tag[0] = BRCM_LEG_TYPE_HI;
242 brcm_tag[1] = BRCM_LEG_TYPE_LO;
243
244 /* Broadcom tag value */
245 brcm_tag[2] = BRCM_LEG_EGRESS;
246 brcm_tag[3] = 0;
247 brcm_tag[4] = 0;
248 brcm_tag[5] = dp->index & BRCM_LEG_PORT_ID;
249
250 return skb;
251 }
252
brcm_leg_tag_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt)253 static struct sk_buff *brcm_leg_tag_rcv(struct sk_buff *skb,
254 struct net_device *dev,
255 struct packet_type *pt)
256 {
257 int source_port;
258 u8 *brcm_tag;
259
260 if (unlikely(!pskb_may_pull(skb, BRCM_LEG_PORT_ID)))
261 return NULL;
262
263 brcm_tag = skb->data - 2;
264
265 source_port = brcm_tag[5] & BRCM_LEG_PORT_ID;
266
267 skb->dev = dsa_master_find_slave(dev, 0, source_port);
268 if (!skb->dev)
269 return NULL;
270
271 /* Remove Broadcom tag and update checksum */
272 skb_pull_rcsum(skb, BRCM_LEG_TAG_LEN);
273
274 skb->offload_fwd_mark = 1;
275
276 /* Move the Ethernet DA and SA */
277 memmove(skb->data - ETH_HLEN,
278 skb->data - ETH_HLEN - BRCM_LEG_TAG_LEN,
279 2 * ETH_ALEN);
280
281 return skb;
282 }
283
284 static const struct dsa_device_ops brcm_legacy_netdev_ops = {
285 .name = "brcm-legacy",
286 .proto = DSA_TAG_PROTO_BRCM_LEGACY,
287 .xmit = brcm_leg_tag_xmit,
288 .rcv = brcm_leg_tag_rcv,
289 .overhead = BRCM_LEG_TAG_LEN,
290 };
291
292 DSA_TAG_DRIVER(brcm_legacy_netdev_ops);
293 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM_LEGACY);
294 #endif /* CONFIG_NET_DSA_TAG_BRCM_LEGACY */
295
296 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
brcm_tag_xmit_prepend(struct sk_buff * skb,struct net_device * dev)297 static struct sk_buff *brcm_tag_xmit_prepend(struct sk_buff *skb,
298 struct net_device *dev)
299 {
300 /* tag is prepended to the packet */
301 return brcm_tag_xmit_ll(skb, dev, 0);
302 }
303
brcm_tag_rcv_prepend(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt)304 static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb,
305 struct net_device *dev,
306 struct packet_type *pt)
307 {
308 /* tag is prepended to the packet */
309 return brcm_tag_rcv_ll(skb, dev, pt, ETH_HLEN);
310 }
311
312 static const struct dsa_device_ops brcm_prepend_netdev_ops = {
313 .name = "brcm-prepend",
314 .proto = DSA_TAG_PROTO_BRCM_PREPEND,
315 .xmit = brcm_tag_xmit_prepend,
316 .rcv = brcm_tag_rcv_prepend,
317 .overhead = BRCM_TAG_LEN,
318 };
319
320 DSA_TAG_DRIVER(brcm_prepend_netdev_ops);
321 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM_PREPEND);
322 #endif
323
324 static struct dsa_tag_driver *dsa_tag_driver_array[] = {
325 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM)
326 &DSA_TAG_DRIVER_NAME(brcm_netdev_ops),
327 #endif
328 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_LEGACY)
329 &DSA_TAG_DRIVER_NAME(brcm_legacy_netdev_ops),
330 #endif
331 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
332 &DSA_TAG_DRIVER_NAME(brcm_prepend_netdev_ops),
333 #endif
334 };
335
336 module_dsa_tag_drivers(dsa_tag_driver_array);
337
338 MODULE_LICENSE("GPL");
339