xref: /linux/net/dsa/tag_brcm.c (revision 06d07429858317ded2db7986113a9e0129cd599b)
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/if_vlan.h>
11 #include <linux/list.h>
12 #include <linux/slab.h>
13 
14 #include "tag.h"
15 
16 #define BRCM_NAME		"brcm"
17 #define BRCM_LEGACY_NAME	"brcm-legacy"
18 #define BRCM_PREPEND_NAME	"brcm-prepend"
19 
20 /* Legacy Broadcom tag (6 bytes) */
21 #define BRCM_LEG_TAG_LEN	6
22 
23 /* Type fields */
24 /* 1st byte in the tag */
25 #define BRCM_LEG_TYPE_HI	0x88
26 /* 2nd byte in the tag */
27 #define BRCM_LEG_TYPE_LO	0x74
28 
29 /* Tag fields */
30 /* 3rd byte in the tag */
31 #define BRCM_LEG_UNICAST	(0 << 5)
32 #define BRCM_LEG_MULTICAST	(1 << 5)
33 #define BRCM_LEG_EGRESS		(2 << 5)
34 #define BRCM_LEG_INGRESS	(3 << 5)
35 
36 /* 6th byte in the tag */
37 #define BRCM_LEG_PORT_ID	(0xf)
38 
39 /* Newer Broadcom tag (4 bytes) */
40 #define BRCM_TAG_LEN	4
41 
42 /* Tag is constructed and deconstructed using byte by byte access
43  * because the tag is placed after the MAC Source Address, which does
44  * not make it 4-bytes aligned, so this might cause unaligned accesses
45  * on most systems where this is used.
46  */
47 
48 /* Ingress and egress opcodes */
49 #define BRCM_OPCODE_SHIFT	5
50 #define BRCM_OPCODE_MASK	0x7
51 
52 /* Ingress fields */
53 /* 1st byte in the tag */
54 #define BRCM_IG_TC_SHIFT	2
55 #define BRCM_IG_TC_MASK		0x7
56 /* 2nd byte in the tag */
57 #define BRCM_IG_TE_MASK		0x3
58 #define BRCM_IG_TS_SHIFT	7
59 /* 3rd byte in the tag */
60 #define BRCM_IG_DSTMAP2_MASK	1
61 #define BRCM_IG_DSTMAP1_MASK	0xff
62 
63 /* Egress fields */
64 
65 /* 2nd byte in the tag */
66 #define BRCM_EG_CID_MASK	0xff
67 
68 /* 3rd byte in the tag */
69 #define BRCM_EG_RC_MASK		0xff
70 #define  BRCM_EG_RC_RSVD	(3 << 6)
71 #define  BRCM_EG_RC_EXCEPTION	(1 << 5)
72 #define  BRCM_EG_RC_PROT_SNOOP	(1 << 4)
73 #define  BRCM_EG_RC_PROT_TERM	(1 << 3)
74 #define  BRCM_EG_RC_SWITCH	(1 << 2)
75 #define  BRCM_EG_RC_MAC_LEARN	(1 << 1)
76 #define  BRCM_EG_RC_MIRROR	(1 << 0)
77 #define BRCM_EG_TC_SHIFT	5
78 #define BRCM_EG_TC_MASK		0x7
79 #define BRCM_EG_PID_MASK	0x1f
80 
81 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM) || \
82 	IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
83 
brcm_tag_xmit_ll(struct sk_buff * skb,struct net_device * dev,unsigned int offset)84 static struct sk_buff *brcm_tag_xmit_ll(struct sk_buff *skb,
85 					struct net_device *dev,
86 					unsigned int offset)
87 {
88 	struct dsa_port *dp = dsa_user_to_port(dev);
89 	u16 queue = skb_get_queue_mapping(skb);
90 	u8 *brcm_tag;
91 
92 	/* The Ethernet switch we are interfaced with needs packets to be at
93 	 * least 64 bytes (including FCS) otherwise they will be discarded when
94 	 * they enter the switch port logic. When Broadcom tags are enabled, we
95 	 * need to make sure that packets are at least 68 bytes
96 	 * (including FCS and tag) because the length verification is done after
97 	 * the Broadcom tag is stripped off the ingress packet.
98 	 *
99 	 * Let dsa_user_xmit() free the SKB
100 	 */
101 	if (__skb_put_padto(skb, ETH_ZLEN + BRCM_TAG_LEN, false))
102 		return NULL;
103 
104 	skb_push(skb, BRCM_TAG_LEN);
105 
106 	if (offset)
107 		dsa_alloc_etype_header(skb, BRCM_TAG_LEN);
108 
109 	brcm_tag = skb->data + offset;
110 
111 	/* Set the ingress opcode, traffic class, tag enforcement is
112 	 * deprecated
113 	 */
114 	brcm_tag[0] = (1 << BRCM_OPCODE_SHIFT) |
115 		       ((queue & BRCM_IG_TC_MASK) << BRCM_IG_TC_SHIFT);
116 	brcm_tag[1] = 0;
117 	brcm_tag[2] = 0;
118 	if (dp->index == 8)
119 		brcm_tag[2] = BRCM_IG_DSTMAP2_MASK;
120 	brcm_tag[3] = (1 << dp->index) & BRCM_IG_DSTMAP1_MASK;
121 
122 	/* Now tell the conduit network device about the desired output queue
123 	 * as well
124 	 */
125 	skb_set_queue_mapping(skb, BRCM_TAG_SET_PORT_QUEUE(dp->index, queue));
126 
127 	return skb;
128 }
129 
130 /* Frames with this tag have one of these two layouts:
131  * -----------------------------------
132  * | MAC DA | MAC SA | 4b tag | Type | DSA_TAG_PROTO_BRCM
133  * -----------------------------------
134  * -----------------------------------
135  * | 4b tag | MAC DA | MAC SA | Type | DSA_TAG_PROTO_BRCM_PREPEND
136  * -----------------------------------
137  * In both cases, at receive time, skb->data points 2 bytes before the actual
138  * Ethernet type field and we have an offset of 4bytes between where skb->data
139  * and where the payload starts. So the same low-level receive function can be
140  * used.
141  */
brcm_tag_rcv_ll(struct sk_buff * skb,struct net_device * dev,unsigned int offset)142 static struct sk_buff *brcm_tag_rcv_ll(struct sk_buff *skb,
143 				       struct net_device *dev,
144 				       unsigned int offset)
145 {
146 	int source_port;
147 	u8 *brcm_tag;
148 
149 	if (unlikely(!pskb_may_pull(skb, BRCM_TAG_LEN)))
150 		return NULL;
151 
152 	brcm_tag = skb->data - offset;
153 
154 	/* The opcode should never be different than 0b000 */
155 	if (unlikely((brcm_tag[0] >> BRCM_OPCODE_SHIFT) & BRCM_OPCODE_MASK))
156 		return NULL;
157 
158 	/* We should never see a reserved reason code without knowing how to
159 	 * handle it
160 	 */
161 	if (unlikely(brcm_tag[2] & BRCM_EG_RC_RSVD))
162 		return NULL;
163 
164 	/* Locate which port this is coming from */
165 	source_port = brcm_tag[3] & BRCM_EG_PID_MASK;
166 
167 	skb->dev = dsa_conduit_find_user(dev, 0, source_port);
168 	if (!skb->dev)
169 		return NULL;
170 
171 	/* Remove Broadcom tag and update checksum */
172 	skb_pull_rcsum(skb, BRCM_TAG_LEN);
173 
174 	dsa_default_offload_fwd_mark(skb);
175 
176 	return skb;
177 }
178 #endif
179 
180 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM)
brcm_tag_xmit(struct sk_buff * skb,struct net_device * dev)181 static struct sk_buff *brcm_tag_xmit(struct sk_buff *skb,
182 				     struct net_device *dev)
183 {
184 	/* Build the tag after the MAC Source Address */
185 	return brcm_tag_xmit_ll(skb, dev, 2 * ETH_ALEN);
186 }
187 
188 
brcm_tag_rcv(struct sk_buff * skb,struct net_device * dev)189 static struct sk_buff *brcm_tag_rcv(struct sk_buff *skb, struct net_device *dev)
190 {
191 	struct sk_buff *nskb;
192 
193 	/* skb->data points to the EtherType, the tag is right before it */
194 	nskb = brcm_tag_rcv_ll(skb, dev, 2);
195 	if (!nskb)
196 		return nskb;
197 
198 	dsa_strip_etype_header(skb, BRCM_TAG_LEN);
199 
200 	return nskb;
201 }
202 
203 static const struct dsa_device_ops brcm_netdev_ops = {
204 	.name	= BRCM_NAME,
205 	.proto	= DSA_TAG_PROTO_BRCM,
206 	.xmit	= brcm_tag_xmit,
207 	.rcv	= brcm_tag_rcv,
208 	.needed_headroom = BRCM_TAG_LEN,
209 };
210 
211 DSA_TAG_DRIVER(brcm_netdev_ops);
212 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM, BRCM_NAME);
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_user_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_user_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 	dsa_alloc_etype_header(skb, BRCM_LEG_TAG_LEN);
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)253 static struct sk_buff *brcm_leg_tag_rcv(struct sk_buff *skb,
254 					struct net_device *dev)
255 {
256 	int len = BRCM_LEG_TAG_LEN;
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 = dsa_etype_header_pos_rx(skb);
264 
265 	source_port = brcm_tag[5] & BRCM_LEG_PORT_ID;
266 
267 	skb->dev = dsa_conduit_find_user(dev, 0, source_port);
268 	if (!skb->dev)
269 		return NULL;
270 
271 	/* VLAN tag is added by BCM63xx internal switch */
272 	if (netdev_uses_dsa(skb->dev))
273 		len += VLAN_HLEN;
274 
275 	/* Remove Broadcom tag and update checksum */
276 	skb_pull_rcsum(skb, len);
277 
278 	dsa_default_offload_fwd_mark(skb);
279 
280 	dsa_strip_etype_header(skb, len);
281 
282 	return skb;
283 }
284 
285 static const struct dsa_device_ops brcm_legacy_netdev_ops = {
286 	.name = BRCM_LEGACY_NAME,
287 	.proto = DSA_TAG_PROTO_BRCM_LEGACY,
288 	.xmit = brcm_leg_tag_xmit,
289 	.rcv = brcm_leg_tag_rcv,
290 	.needed_headroom = BRCM_LEG_TAG_LEN,
291 };
292 
293 DSA_TAG_DRIVER(brcm_legacy_netdev_ops);
294 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM_LEGACY, BRCM_LEGACY_NAME);
295 #endif /* CONFIG_NET_DSA_TAG_BRCM_LEGACY */
296 
297 #if IS_ENABLED(CONFIG_NET_DSA_TAG_BRCM_PREPEND)
brcm_tag_xmit_prepend(struct sk_buff * skb,struct net_device * dev)298 static struct sk_buff *brcm_tag_xmit_prepend(struct sk_buff *skb,
299 					     struct net_device *dev)
300 {
301 	/* tag is prepended to the packet */
302 	return brcm_tag_xmit_ll(skb, dev, 0);
303 }
304 
brcm_tag_rcv_prepend(struct sk_buff * skb,struct net_device * dev)305 static struct sk_buff *brcm_tag_rcv_prepend(struct sk_buff *skb,
306 					    struct net_device *dev)
307 {
308 	/* tag is prepended to the packet */
309 	return brcm_tag_rcv_ll(skb, dev, ETH_HLEN);
310 }
311 
312 static const struct dsa_device_ops brcm_prepend_netdev_ops = {
313 	.name	= BRCM_PREPEND_NAME,
314 	.proto	= DSA_TAG_PROTO_BRCM_PREPEND,
315 	.xmit	= brcm_tag_xmit_prepend,
316 	.rcv	= brcm_tag_rcv_prepend,
317 	.needed_headroom = BRCM_TAG_LEN,
318 };
319 
320 DSA_TAG_DRIVER(brcm_prepend_netdev_ops);
321 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_BRCM_PREPEND, BRCM_PREPEND_NAME);
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_DESCRIPTION("DSA tag driver for Broadcom switches using in-frame headers");
339 MODULE_LICENSE("GPL");
340