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