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