1 /*
2 * net/dsa/tag_edsa.c - Ethertype DSA tagging
3 * Copyright (c) 2008-2009 Marvell Semiconductor
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 */
10
11 #include <linux/etherdevice.h>
12 #include <linux/list.h>
13 #include <linux/slab.h>
14
15 #include "dsa_priv.h"
16
17 #define DSA_HLEN 4
18 #define EDSA_HLEN 8
19
edsa_xmit(struct sk_buff * skb,struct net_device * dev)20 static struct sk_buff *edsa_xmit(struct sk_buff *skb, struct net_device *dev)
21 {
22 struct dsa_slave_priv *p = netdev_priv(dev);
23 u8 *edsa_header;
24
25 /*
26 * Convert the outermost 802.1q tag to a DSA tag and prepend
27 * a DSA ethertype field is the packet is tagged, or insert
28 * a DSA ethertype plus DSA tag between the addresses and the
29 * current ethertype field if the packet is untagged.
30 */
31 if (skb->protocol == htons(ETH_P_8021Q)) {
32 if (skb_cow_head(skb, DSA_HLEN) < 0)
33 return NULL;
34 skb_push(skb, DSA_HLEN);
35
36 memmove(skb->data, skb->data + DSA_HLEN, 2 * ETH_ALEN);
37
38 /*
39 * Construct tagged FROM_CPU DSA tag from 802.1q tag.
40 */
41 edsa_header = skb->data + 2 * ETH_ALEN;
42 edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
43 edsa_header[1] = ETH_P_EDSA & 0xff;
44 edsa_header[2] = 0x00;
45 edsa_header[3] = 0x00;
46 edsa_header[4] = 0x60 | p->dp->ds->index;
47 edsa_header[5] = p->dp->index << 3;
48
49 /*
50 * Move CFI field from byte 6 to byte 5.
51 */
52 if (edsa_header[6] & 0x10) {
53 edsa_header[5] |= 0x01;
54 edsa_header[6] &= ~0x10;
55 }
56 } else {
57 if (skb_cow_head(skb, EDSA_HLEN) < 0)
58 return NULL;
59 skb_push(skb, EDSA_HLEN);
60
61 memmove(skb->data, skb->data + EDSA_HLEN, 2 * ETH_ALEN);
62
63 /*
64 * Construct untagged FROM_CPU DSA tag.
65 */
66 edsa_header = skb->data + 2 * ETH_ALEN;
67 edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
68 edsa_header[1] = ETH_P_EDSA & 0xff;
69 edsa_header[2] = 0x00;
70 edsa_header[3] = 0x00;
71 edsa_header[4] = 0x40 | p->dp->ds->index;
72 edsa_header[5] = p->dp->index << 3;
73 edsa_header[6] = 0x00;
74 edsa_header[7] = 0x00;
75 }
76
77 return skb;
78 }
79
edsa_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt)80 static struct sk_buff *edsa_rcv(struct sk_buff *skb, struct net_device *dev,
81 struct packet_type *pt)
82 {
83 struct dsa_switch_tree *dst = dev->dsa_ptr;
84 struct dsa_switch *ds;
85 u8 *edsa_header;
86 int source_device;
87 int source_port;
88
89 if (unlikely(!pskb_may_pull(skb, EDSA_HLEN)))
90 return NULL;
91
92 /*
93 * Skip the two null bytes after the ethertype.
94 */
95 edsa_header = skb->data + 2;
96
97 /*
98 * Check that frame type is either TO_CPU or FORWARD.
99 */
100 if ((edsa_header[0] & 0xc0) != 0x00 && (edsa_header[0] & 0xc0) != 0xc0)
101 return NULL;
102
103 /*
104 * Determine source device and port.
105 */
106 source_device = edsa_header[0] & 0x1f;
107 source_port = (edsa_header[1] >> 3) & 0x1f;
108
109 /*
110 * Check that the source device exists and that the source
111 * port is a registered DSA port.
112 */
113 if (source_device >= DSA_MAX_SWITCHES)
114 return NULL;
115
116 ds = dst->ds[source_device];
117 if (!ds)
118 return NULL;
119
120 if (source_port >= ds->num_ports || !ds->ports[source_port].netdev)
121 return NULL;
122
123 if (unlikely(ds->cpu_port_mask & BIT(source_port)))
124 return NULL;
125
126 /*
127 * If the 'tagged' bit is set, convert the DSA tag to a 802.1q
128 * tag and delete the ethertype part. If the 'tagged' bit is
129 * clear, delete the ethertype and the DSA tag parts.
130 */
131 if (edsa_header[0] & 0x20) {
132 u8 new_header[4];
133
134 /*
135 * Insert 802.1q ethertype and copy the VLAN-related
136 * fields, but clear the bit that will hold CFI (since
137 * DSA uses that bit location for another purpose).
138 */
139 new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
140 new_header[1] = ETH_P_8021Q & 0xff;
141 new_header[2] = edsa_header[2] & ~0x10;
142 new_header[3] = edsa_header[3];
143
144 /*
145 * Move CFI bit from its place in the DSA header to
146 * its 802.1q-designated place.
147 */
148 if (edsa_header[1] & 0x01)
149 new_header[2] |= 0x10;
150
151 skb_pull_rcsum(skb, DSA_HLEN);
152
153 /*
154 * Update packet checksum if skb is CHECKSUM_COMPLETE.
155 */
156 if (skb->ip_summed == CHECKSUM_COMPLETE) {
157 __wsum c = skb->csum;
158 c = csum_add(c, csum_partial(new_header + 2, 2, 0));
159 c = csum_sub(c, csum_partial(edsa_header + 2, 2, 0));
160 skb->csum = c;
161 }
162
163 memcpy(edsa_header, new_header, DSA_HLEN);
164
165 memmove(skb->data - ETH_HLEN,
166 skb->data - ETH_HLEN - DSA_HLEN,
167 2 * ETH_ALEN);
168 } else {
169 /*
170 * Remove DSA tag and update checksum.
171 */
172 skb_pull_rcsum(skb, EDSA_HLEN);
173 memmove(skb->data - ETH_HLEN,
174 skb->data - ETH_HLEN - EDSA_HLEN,
175 2 * ETH_ALEN);
176 }
177
178 skb->dev = ds->ports[source_port].netdev;
179
180 return skb;
181 }
182
183 const struct dsa_device_ops edsa_netdev_ops = {
184 .xmit = edsa_xmit,
185 .rcv = edsa_rcv,
186 };
187