1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * net/dsa/tag_edsa.c - Ethertype DSA tagging
4 * Copyright (c) 2008-2009 Marvell Semiconductor
5 */
6
7 #include <linux/etherdevice.h>
8 #include <linux/list.h>
9 #include <linux/slab.h>
10
11 #include "dsa_priv.h"
12
13 #define DSA_HLEN 4
14 #define EDSA_HLEN 8
15
16 #define FRAME_TYPE_TO_CPU 0x00
17 #define FRAME_TYPE_FORWARD 0x03
18
19 #define TO_CPU_CODE_MGMT_TRAP 0x00
20 #define TO_CPU_CODE_FRAME2REG 0x01
21 #define TO_CPU_CODE_IGMP_MLD_TRAP 0x02
22 #define TO_CPU_CODE_POLICY_TRAP 0x03
23 #define TO_CPU_CODE_ARP_MIRROR 0x04
24 #define TO_CPU_CODE_POLICY_MIRROR 0x05
25
edsa_xmit(struct sk_buff * skb,struct net_device * dev)26 static struct sk_buff *edsa_xmit(struct sk_buff *skb, struct net_device *dev)
27 {
28 struct dsa_port *dp = dsa_slave_to_port(dev);
29 u8 *edsa_header;
30
31 /*
32 * Convert the outermost 802.1q tag to a DSA tag and prepend
33 * a DSA ethertype field is the packet is tagged, or insert
34 * a DSA ethertype plus DSA tag between the addresses and the
35 * current ethertype field if the packet is untagged.
36 */
37 if (skb->protocol == htons(ETH_P_8021Q)) {
38 if (skb_cow_head(skb, DSA_HLEN) < 0)
39 return NULL;
40 skb_push(skb, DSA_HLEN);
41
42 memmove(skb->data, skb->data + DSA_HLEN, 2 * ETH_ALEN);
43
44 /*
45 * Construct tagged FROM_CPU DSA tag from 802.1q tag.
46 */
47 edsa_header = skb->data + 2 * ETH_ALEN;
48 edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
49 edsa_header[1] = ETH_P_EDSA & 0xff;
50 edsa_header[2] = 0x00;
51 edsa_header[3] = 0x00;
52 edsa_header[4] = 0x60 | dp->ds->index;
53 edsa_header[5] = dp->index << 3;
54
55 /*
56 * Move CFI field from byte 6 to byte 5.
57 */
58 if (edsa_header[6] & 0x10) {
59 edsa_header[5] |= 0x01;
60 edsa_header[6] &= ~0x10;
61 }
62 } else {
63 if (skb_cow_head(skb, EDSA_HLEN) < 0)
64 return NULL;
65 skb_push(skb, EDSA_HLEN);
66
67 memmove(skb->data, skb->data + EDSA_HLEN, 2 * ETH_ALEN);
68
69 /*
70 * Construct untagged FROM_CPU DSA tag.
71 */
72 edsa_header = skb->data + 2 * ETH_ALEN;
73 edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
74 edsa_header[1] = ETH_P_EDSA & 0xff;
75 edsa_header[2] = 0x00;
76 edsa_header[3] = 0x00;
77 edsa_header[4] = 0x40 | dp->ds->index;
78 edsa_header[5] = dp->index << 3;
79 edsa_header[6] = 0x00;
80 edsa_header[7] = 0x00;
81 }
82
83 return skb;
84 }
85
edsa_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt)86 static struct sk_buff *edsa_rcv(struct sk_buff *skb, struct net_device *dev,
87 struct packet_type *pt)
88 {
89 u8 *edsa_header;
90 int frame_type;
91 int code;
92 int source_device;
93 int source_port;
94
95 if (unlikely(!pskb_may_pull(skb, EDSA_HLEN)))
96 return NULL;
97
98 /*
99 * Skip the two null bytes after the ethertype.
100 */
101 edsa_header = skb->data + 2;
102
103 /*
104 * Check that frame type is either TO_CPU or FORWARD.
105 */
106 frame_type = edsa_header[0] >> 6;
107
108 switch (frame_type) {
109 case FRAME_TYPE_TO_CPU:
110 code = (edsa_header[1] & 0x6) | ((edsa_header[2] >> 4) & 1);
111
112 /*
113 * Mark the frame to never egress on any port of the same switch
114 * unless it's a trapped IGMP/MLD packet, in which case the
115 * bridge might want to forward it.
116 */
117 if (code != TO_CPU_CODE_IGMP_MLD_TRAP)
118 skb->offload_fwd_mark = 1;
119
120 break;
121
122 case FRAME_TYPE_FORWARD:
123 skb->offload_fwd_mark = 1;
124 break;
125
126 default:
127 return NULL;
128 }
129
130 /*
131 * Determine source device and port.
132 */
133 source_device = edsa_header[0] & 0x1f;
134 source_port = (edsa_header[1] >> 3) & 0x1f;
135
136 skb->dev = dsa_master_find_slave(dev, source_device, source_port);
137 if (!skb->dev)
138 return NULL;
139
140 /*
141 * If the 'tagged' bit is set, convert the DSA tag to a 802.1q
142 * tag and delete the ethertype part. If the 'tagged' bit is
143 * clear, delete the ethertype and the DSA tag parts.
144 */
145 if (edsa_header[0] & 0x20) {
146 u8 new_header[4];
147
148 /*
149 * Insert 802.1q ethertype and copy the VLAN-related
150 * fields, but clear the bit that will hold CFI (since
151 * DSA uses that bit location for another purpose).
152 */
153 new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
154 new_header[1] = ETH_P_8021Q & 0xff;
155 new_header[2] = edsa_header[2] & ~0x10;
156 new_header[3] = edsa_header[3];
157
158 /*
159 * Move CFI bit from its place in the DSA header to
160 * its 802.1q-designated place.
161 */
162 if (edsa_header[1] & 0x01)
163 new_header[2] |= 0x10;
164
165 skb_pull_rcsum(skb, DSA_HLEN);
166
167 /*
168 * Update packet checksum if skb is CHECKSUM_COMPLETE.
169 */
170 if (skb->ip_summed == CHECKSUM_COMPLETE) {
171 __wsum c = skb->csum;
172 c = csum_add(c, csum_partial(new_header + 2, 2, 0));
173 c = csum_sub(c, csum_partial(edsa_header + 2, 2, 0));
174 skb->csum = c;
175 }
176
177 memcpy(edsa_header, new_header, DSA_HLEN);
178
179 memmove(skb->data - ETH_HLEN,
180 skb->data - ETH_HLEN - DSA_HLEN,
181 2 * ETH_ALEN);
182 } else {
183 /*
184 * Remove DSA tag and update checksum.
185 */
186 skb_pull_rcsum(skb, EDSA_HLEN);
187 memmove(skb->data - ETH_HLEN,
188 skb->data - ETH_HLEN - EDSA_HLEN,
189 2 * ETH_ALEN);
190 }
191
192 return skb;
193 }
194
195 static const struct dsa_device_ops edsa_netdev_ops = {
196 .name = "edsa",
197 .proto = DSA_TAG_PROTO_EDSA,
198 .xmit = edsa_xmit,
199 .rcv = edsa_rcv,
200 .overhead = EDSA_HLEN,
201 };
202
203 MODULE_LICENSE("GPL");
204 MODULE_ALIAS_DSA_TAG_DRIVER(DSA_TAG_PROTO_EDSA);
205
206 module_dsa_tag_driver(edsa_netdev_ops);
207
