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