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