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 dsa_alloc_etype_header(skb, BRCM_TAG_LEN);
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,unsigned int offset)137 static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,
138 struct net_device *dev,
139 unsigned int offset)
140 {
141 int source_port;
142 u8 *brcm_tag;
143
144 if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN)))
145 return NULL;
146
147 brcm_tag = skb->data - offset;
148
149 /* The opcode should never be different than 0b000 */
150 if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK))
151 return NULL;
152
153 /* We should never see a reserved reason code without knowing how to
154 * handle it
155 */
156 if (unlikely(brcm_tag[2] & BRCM_EG_RC_RSVD))
157 return NULL;
158
159 /* Locate which port this is coming from */
160 source_port = brcm_tag[3] & BRCM_EG_PID_MASK;
161
162 skb->dev = dsa_master_find_slave(dev, 0, source_port);
163 if (!skb->dev)
164 return NULL;
165
166 /* Remove Broadcom tag and update checksum */
167 skb_pull_rcsum(skb, BRCM_TAG_LEN);
168
169 dsa_default_offload_fwd_mark(skb);
170
171 return skb;
172 }
173 #endif
174
175 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM)
brcm_tag_xmit(struct sk_buff * skb,struct net_device * dev)176 static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb,
177 struct net_device *dev)
178 {
179 /* Build the tag after the MAC Source Address */
180 return brcm_tag_xmit_ll(skb, dev, 2 * ETH_ALEN);
181 }
182
183
brcm_tag_rcv(struct sk_buff * skb,struct net_device * dev)184 static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev)
185 {
186 struct sk_buff *nskb;
187
188 /* skb->data points to the EtherType, the tag is right before it */
189 nskb = brcm_tag_rcv_ll(skb, dev, 2);
190 if (!nskb)
191 return nskb;
192
193 dsa_strip_etype_header(skb, BRCM_TAG_LEN);
194
195 return nskb;
196 }
197
198 static const struct dsa_device_ops brcm_netdev_ops = {
199 .name = "brcm",
200 .proto = DSA_TAG_PROTO_BRCM,
201 .xmit = brcm_tag_xmit,
202 .rcv = brcm_tag_rcv,
203 .needed_headroom = BRCM_TAG_LEN,
204 };
205
206 DSA_TAG_DRIVER(brcm_netdev_ops);
207 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM);
208 #endif
209
210 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_LEGACY)
brcm_leg_tag_xmit(struct sk_buff * skb,struct net_device * dev)211 static struct sk_buff *brcm_leg_tag_xmit(struct sk_buff *skb,
212 struct net_device *dev)
213 {
214 struct dsa_port *dp = dsa_slave_to_port(dev);
215 u8 *brcm_tag;
216
217 /* The Ethernet switch we are interfaced with needs packets to be at
218 * least 64 bytes (including FCS) otherwise they will be discarded when
219 * they enter the switch port logic. When Broadcom tags are enabled, we
220 * need to make sure that packets are at least 70 bytes
221 * (including FCS and tag) because the length verification is done after
222 * the Broadcom tag is stripped off the ingress packet.
223 *
224 * Let dsa_slave_xmit() free the SKB
225 */
226 if (__skb_put_padto(skb, ETH_ZLEN + BRCM_LEG_TAG_LEN, false))
227 return NULL;
228
229 skb_push(skb, BRCM_LEG_TAG_LEN);
230
231 dsa_alloc_etype_header(skb, BRCM_LEG_TAG_LEN);
232
233 brcm_tag = skb->data + 2 * ETH_ALEN;
234
235 /* Broadcom tag type */
236 brcm_tag[0] = BRCM_LEG_TYPE_HI;
237 brcm_tag[1] = BRCM_LEG_TYPE_LO;
238
239 /* Broadcom tag value */
240 brcm_tag[2] = BRCM_LEG_EGRESS;
241 brcm_tag[3] = 0;
242 brcm_tag[4] = 0;
243 brcm_tag[5] = dp->index & BRCM_LEG_PORT_ID;
244
245 return skb;
246 }
247
brcm_leg_tag_rcv(struct sk_buff * skb,struct net_device * dev)248 static struct sk_buff *brcm_leg_tag_rcv(struct sk_buff *skb,
249 struct net_device *dev)
250 {
251 int source_port;
252 u8 *brcm_tag;
253
254 if (unlikely(!pskb_may_pull(skb, BRCM_LEG_PORT_ID)))
255 return NULL;
256
257 brcm_tag = dsa_etype_header_pos_rx(skb);
258
259 source_port = brcm_tag[5] & BRCM_LEG_PORT_ID;
260
261 skb->dev = dsa_master_find_slave(dev, 0, source_port);
262 if (!skb->dev)
263 return NULL;
264
265 /* Remove Broadcom tag and update checksum */
266 skb_pull_rcsum(skb, BRCM_LEG_TAG_LEN);
267
268 dsa_default_offload_fwd_mark(skb);
269
270 dsa_strip_etype_header(skb, BRCM_LEG_TAG_LEN);
271
272 return skb;
273 }
274
275 static const struct dsa_device_ops brcm_legacy_netdev_ops = {
276 .name = "brcm-legacy",
277 .proto = DSA_TAG_PROTO_BRCM_LEGACY,
278 .xmit = brcm_leg_tag_xmit,
279 .rcv = brcm_leg_tag_rcv,
280 .needed_headroom = BRCM_LEG_TAG_LEN,
281 };
282
283 DSA_TAG_DRIVER(brcm_legacy_netdev_ops);
284 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM_LEGACY);
285 #endif /* CONFIG_NET_DSA_TAG_BRCM_LEGACY */
286
287 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
brcm_tag_xmit_prepend(struct sk_buff * skb,struct net_device * dev)288 static struct sk_buff *brcm_tag_xmit_prepend(struct sk_buff *skb,
289 struct net_device *dev)
290 {
291 /* tag is prepended to the packet */
292 return brcm_tag_xmit_ll(skb, dev, 0);
293 }
294
brcm_tag_rcv_prepend(struct sk_buff * skb,struct net_device * dev)295 static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb,
296 struct net_device *dev)
297 {
298 /* tag is prepended to the packet */
299 return brcm_tag_rcv_ll(skb, dev, ETH_HLEN);
300 }
301
302 static const struct dsa_device_ops brcm_prepend_netdev_ops = {
303 .name = "brcm-prepend",
304 .proto = DSA_TAG_PROTO_BRCM_PREPEND,
305 .xmit = brcm_tag_xmit_prepend,
306 .rcv = brcm_tag_rcv_prepend,
307 .needed_headroom = BRCM_TAG_LEN,
308 };
309
310 DSA_TAG_DRIVER(brcm_prepend_netdev_ops);
311 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM_PREPEND);
312 #endif
313
314 static struct dsa_tag_driver *dsa_tag_driver_array[] = {
315 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM)
316 &DSA_TAG_DRIVER_NAME(brcm_netdev_ops),
317 #endif
318 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_LEGACY)
319 &DSA_TAG_DRIVER_NAME(brcm_legacy_netdev_ops),
320 #endif
321 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
322 &DSA_TAG_DRIVER_NAME(brcm_prepend_netdev_ops),
323 #endif
324 };
325
326 module_dsa_tag_drivers(dsa_tag_driver_array);
327
328 MODULE_LICENSE("GPL");
329