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 #include "dsa_priv.h"
15
16 #define DSA_HLEN 4
17 #define EDSA_HLEN 8
18
edsa_xmit(struct sk_buff * skb,struct net_device * dev)19 static netdev_tx_t edsa_xmit(struct sk_buff *skb, struct net_device *dev)
20 {
21 struct dsa_slave_priv *p = netdev_priv(dev);
22 u8 *edsa_header;
23
24 dev->stats.tx_packets++;
25 dev->stats.tx_bytes += skb->len;
26
27 /*
28 * Convert the outermost 802.1q tag to a DSA tag and prepend
29 * a DSA ethertype field is the packet is tagged, or insert
30 * a DSA ethertype plus DSA tag between the addresses and the
31 * current ethertype field if the packet is untagged.
32 */
33 if (skb->protocol == htons(ETH_P_8021Q)) {
34 if (skb_cow_head(skb, DSA_HLEN) < 0)
35 goto out_free;
36 skb_push(skb, DSA_HLEN);
37
38 memmove(skb->data, skb->data + DSA_HLEN, 2 * ETH_ALEN);
39
40 /*
41 * Construct tagged FROM_CPU DSA tag from 802.1q tag.
42 */
43 edsa_header = skb->data + 2 * ETH_ALEN;
44 edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
45 edsa_header[1] = ETH_P_EDSA & 0xff;
46 edsa_header[2] = 0x00;
47 edsa_header[3] = 0x00;
48 edsa_header[4] = 0x60 | p->parent->index;
49 edsa_header[5] = p->port << 3;
50
51 /*
52 * Move CFI field from byte 6 to byte 5.
53 */
54 if (edsa_header[6] & 0x10) {
55 edsa_header[5] |= 0x01;
56 edsa_header[6] &= ~0x10;
57 }
58 } else {
59 if (skb_cow_head(skb, EDSA_HLEN) < 0)
60 goto out_free;
61 skb_push(skb, EDSA_HLEN);
62
63 memmove(skb->data, skb->data + EDSA_HLEN, 2 * ETH_ALEN);
64
65 /*
66 * Construct untagged FROM_CPU DSA tag.
67 */
68 edsa_header = skb->data + 2 * ETH_ALEN;
69 edsa_header[0] = (ETH_P_EDSA >> 8) & 0xff;
70 edsa_header[1] = ETH_P_EDSA & 0xff;
71 edsa_header[2] = 0x00;
72 edsa_header[3] = 0x00;
73 edsa_header[4] = 0x40 | p->parent->index;
74 edsa_header[5] = p->port << 3;
75 edsa_header[6] = 0x00;
76 edsa_header[7] = 0x00;
77 }
78
79 skb->protocol = htons(ETH_P_EDSA);
80
81 skb->dev = p->parent->dst->master_netdev;
82 dev_queue_xmit(skb);
83
84 return NETDEV_TX_OK;
85
86 out_free:
87 kfree_skb(skb);
88 return NETDEV_TX_OK;
89 }
90
edsa_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * pt,struct net_device * orig_dev)91 static int edsa_rcv(struct sk_buff *skb, struct net_device *dev,
92 struct packet_type *pt, struct net_device *orig_dev)
93 {
94 struct dsa_switch_tree *dst = dev->dsa_ptr;
95 struct dsa_switch *ds;
96 u8 *edsa_header;
97 int source_device;
98 int source_port;
99
100 if (unlikely(dst == NULL))
101 goto out_drop;
102
103 skb = skb_unshare(skb, GFP_ATOMIC);
104 if (skb == NULL)
105 goto out;
106
107 if (unlikely(!pskb_may_pull(skb, EDSA_HLEN)))
108 goto out_drop;
109
110 /*
111 * Skip the two null bytes after the ethertype.
112 */
113 edsa_header = skb->data + 2;
114
115 /*
116 * Check that frame type is either TO_CPU or FORWARD.
117 */
118 if ((edsa_header[0] & 0xc0) != 0x00 && (edsa_header[0] & 0xc0) != 0xc0)
119 goto out_drop;
120
121 /*
122 * Determine source device and port.
123 */
124 source_device = edsa_header[0] & 0x1f;
125 source_port = (edsa_header[1] >> 3) & 0x1f;
126
127 /*
128 * Check that the source device exists and that the source
129 * port is a registered DSA port.
130 */
131 if (source_device >= dst->pd->nr_chips)
132 goto out_drop;
133 ds = dst->ds[source_device];
134 if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL)
135 goto out_drop;
136
137 /*
138 * If the 'tagged' bit is set, convert the DSA tag to a 802.1q
139 * tag and delete the ethertype part. If the 'tagged' bit is
140 * clear, delete the ethertype and the DSA tag parts.
141 */
142 if (edsa_header[0] & 0x20) {
143 u8 new_header[4];
144
145 /*
146 * Insert 802.1q ethertype and copy the VLAN-related
147 * fields, but clear the bit that will hold CFI (since
148 * DSA uses that bit location for another purpose).
149 */
150 new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
151 new_header[1] = ETH_P_8021Q & 0xff;
152 new_header[2] = edsa_header[2] & ~0x10;
153 new_header[3] = edsa_header[3];
154
155 /*
156 * Move CFI bit from its place in the DSA header to
157 * its 802.1q-designated place.
158 */
159 if (edsa_header[1] & 0x01)
160 new_header[2] |= 0x10;
161
162 skb_pull_rcsum(skb, DSA_HLEN);
163
164 /*
165 * Update packet checksum if skb is CHECKSUM_COMPLETE.
166 */
167 if (skb->ip_summed == CHECKSUM_COMPLETE) {
168 __wsum c = skb->csum;
169 c = csum_add(c, csum_partial(new_header + 2, 2, 0));
170 c = csum_sub(c, csum_partial(edsa_header + 2, 2, 0));
171 skb->csum = c;
172 }
173
174 memcpy(edsa_header, new_header, DSA_HLEN);
175
176 memmove(skb->data - ETH_HLEN,
177 skb->data - ETH_HLEN - DSA_HLEN,
178 2 * ETH_ALEN);
179 } else {
180 /*
181 * Remove DSA tag and update checksum.
182 */
183 skb_pull_rcsum(skb, EDSA_HLEN);
184 memmove(skb->data - ETH_HLEN,
185 skb->data - ETH_HLEN - EDSA_HLEN,
186 2 * ETH_ALEN);
187 }
188
189 skb->dev = ds->ports[source_port];
190 skb_push(skb, ETH_HLEN);
191 skb->pkt_type = PACKET_HOST;
192 skb->protocol = eth_type_trans(skb, skb->dev);
193
194 skb->dev->stats.rx_packets++;
195 skb->dev->stats.rx_bytes += skb->len;
196
197 netif_receive_skb(skb);
198
199 return 0;
200
201 out_drop:
202 kfree_skb(skb);
203 out:
204 return 0;
205 }
206
207 const struct dsa_device_ops edsa_netdev_ops = {
208 .xmit = edsa_xmit,
209 .rcv = edsa_rcv,
210 };
211