1 /*
2 * net/dsa/tag_dsa.c - (Non-ethertype) DSA tagging
3 * Copyright (c) 2008 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/netdevice.h>
14 #include "dsa_priv.h"
15
16 #define DSA_HLEN 4
17
dsa_xmit(struct sk_buff * skb,struct net_device * dev)18 int 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;
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;
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->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 *ds = dev->dsa_ptr;
82 u8 *dsa_header;
83 int source_port;
84
85 if (unlikely(ds == NULL))
86 goto out_drop;
87
88 skb = skb_unshare(skb, GFP_ATOMIC);
89 if (skb == NULL)
90 goto out;
91
92 if (unlikely(!pskb_may_pull(skb, DSA_HLEN)))
93 goto out_drop;
94
95 /*
96 * The ethertype field is part of the DSA header.
97 */
98 dsa_header = skb->data - 2;
99
100 /*
101 * Check that frame type is either TO_CPU or FORWARD, and
102 * that the source device is zero.
103 */
104 if ((dsa_header[0] & 0xdf) != 0x00 && (dsa_header[0] & 0xdf) != 0xc0)
105 goto out_drop;
106
107 /*
108 * Check that the source port is a registered DSA port.
109 */
110 source_port = (dsa_header[1] >> 3) & 0x1f;
111 if (source_port >= DSA_MAX_PORTS || ds->ports[source_port] == NULL)
112 goto out_drop;
113
114 /*
115 * Convert the DSA header to an 802.1q header if the 'tagged'
116 * bit in the DSA header is set. If the 'tagged' bit is clear,
117 * delete the DSA header entirely.
118 */
119 if (dsa_header[0] & 0x20) {
120 u8 new_header[4];
121
122 /*
123 * Insert 802.1q ethertype and copy the VLAN-related
124 * fields, but clear the bit that will hold CFI (since
125 * DSA uses that bit location for another purpose).
126 */
127 new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
128 new_header[1] = ETH_P_8021Q & 0xff;
129 new_header[2] = dsa_header[2] & ~0x10;
130 new_header[3] = dsa_header[3];
131
132 /*
133 * Move CFI bit from its place in the DSA header to
134 * its 802.1q-designated place.
135 */
136 if (dsa_header[1] & 0x01)
137 new_header[2] |= 0x10;
138
139 /*
140 * Update packet checksum if skb is CHECKSUM_COMPLETE.
141 */
142 if (skb->ip_summed == CHECKSUM_COMPLETE) {
143 __wsum c = skb->csum;
144 c = csum_add(c, csum_partial(new_header + 2, 2, 0));
145 c = csum_sub(c, csum_partial(dsa_header + 2, 2, 0));
146 skb->csum = c;
147 }
148
149 memcpy(dsa_header, new_header, DSA_HLEN);
150 } else {
151 /*
152 * Remove DSA tag and update checksum.
153 */
154 skb_pull_rcsum(skb, DSA_HLEN);
155 memmove(skb->data - ETH_HLEN,
156 skb->data - ETH_HLEN - DSA_HLEN,
157 2 * ETH_ALEN);
158 }
159
160 skb->dev = ds->ports[source_port];
161 skb_push(skb, ETH_HLEN);
162 skb->pkt_type = PACKET_HOST;
163 skb->protocol = eth_type_trans(skb, skb->dev);
164
165 skb->dev->stats.rx_packets++;
166 skb->dev->stats.rx_bytes += skb->len;
167
168 netif_receive_skb(skb);
169
170 return 0;
171
172 out_drop:
173 kfree_skb(skb);
174 out:
175 return 0;
176 }
177
178 static struct packet_type dsa_packet_type = {
179 .type = __constant_htons(ETH_P_DSA),
180 .func = dsa_rcv,
181 };
182
dsa_init_module(void)183 static int __init dsa_init_module(void)
184 {
185 dev_add_pack(&dsa_packet_type);
186 return 0;
187 }
188 module_init(dsa_init_module);
189
dsa_cleanup_module(void)190 static void __exit dsa_cleanup_module(void)
191 {
192 dev_remove_pack(&dsa_packet_type);
193 }
194 module_exit(dsa_cleanup_module);
195