tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 <net/dsa.h>
15#include "dsa_priv.h"
16
17#define DSA_HLEN 4
18
19static struct sk_buff *dsa_xmit(struct sk_buff *skb, struct net_device *dev)
20{
21 struct dsa_slave_priv *p = netdev_priv(dev);
22 u8 *dsa_header;
23
24 /*
25 * Convert the outermost 802.1q tag to a DSA tag for tagged
26 * packets, or insert a DSA tag between the addresses and
27 * the ethertype field for untagged packets.
28 */
29 if (skb->protocol == htons(ETH_P_8021Q)) {
30 if (skb_cow_head(skb, 0) < 0)
31 goto out_free;
32
33 /*
34 * Construct tagged FROM_CPU DSA tag from 802.1q tag.
35 */
36 dsa_header = skb->data + 2 * ETH_ALEN;
37 dsa_header[0] = 0x60 | p->dp->ds->index;
38 dsa_header[1] = p->dp->index << 3;
39
40 /*
41 * Move CFI field from byte 2 to byte 1.
42 */
43 if (dsa_header[2] & 0x10) {
44 dsa_header[1] |= 0x01;
45 dsa_header[2] &= ~0x10;
46 }
47 } else {
48 if (skb_cow_head(skb, DSA_HLEN) < 0)
49 goto out_free;
50 skb_push(skb, DSA_HLEN);
51
52 memmove(skb->data, skb->data + DSA_HLEN, 2 * ETH_ALEN);
53
54 /*
55 * Construct untagged FROM_CPU DSA tag.
56 */
57 dsa_header = skb->data + 2 * ETH_ALEN;
58 dsa_header[0] = 0x40 | p->dp->ds->index;
59 dsa_header[1] = p->dp->index << 3;
60 dsa_header[2] = 0x00;
61 dsa_header[3] = 0x00;
62 }
63
64 return skb;
65
66out_free:
67 kfree_skb(skb);
68 return NULL;
69}
70
71static struct sk_buff *dsa_rcv(struct sk_buff *skb, struct net_device *dev,
72 struct packet_type *pt,
73 struct net_device *orig_dev)
74{
75 struct dsa_switch_tree *dst = dev->dsa_ptr;
76 struct dsa_switch *ds;
77 u8 *dsa_header;
78 int source_device;
79 int source_port;
80
81 if (unlikely(!pskb_may_pull(skb, DSA_HLEN)))
82 goto out_drop;
83
84 /*
85 * The ethertype field is part of the DSA header.
86 */
87 dsa_header = skb->data - 2;
88
89 /*
90 * Check that frame type is either TO_CPU or FORWARD.
91 */
92 if ((dsa_header[0] & 0xc0) != 0x00 && (dsa_header[0] & 0xc0) != 0xc0)
93 goto out_drop;
94
95 /*
96 * Determine source device and port.
97 */
98 source_device = dsa_header[0] & 0x1f;
99 source_port = (dsa_header[1] >> 3) & 0x1f;
100
101 /*
102 * Check that the source device exists and that the source
103 * port is a registered DSA port.
104 */
105 if (source_device >= DSA_MAX_SWITCHES)
106 goto out_drop;
107
108 ds = dst->ds[source_device];
109 if (!ds)
110 goto out_drop;
111
112 if (source_port >= ds->num_ports || !ds->ports[source_port].netdev)
113 goto out_drop;
114
115 /*
116 * Convert the DSA header to an 802.1q header if the 'tagged'
117 * bit in the DSA header is set. If the 'tagged' bit is clear,
118 * delete the DSA header entirely.
119 */
120 if (dsa_header[0] & 0x20) {
121 u8 new_header[4];
122
123 /*
124 * Insert 802.1q ethertype and copy the VLAN-related
125 * fields, but clear the bit that will hold CFI (since
126 * DSA uses that bit location for another purpose).
127 */
128 new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
129 new_header[1] = ETH_P_8021Q & 0xff;
130 new_header[2] = dsa_header[2] & ~0x10;
131 new_header[3] = dsa_header[3];
132
133 /*
134 * Move CFI bit from its place in the DSA header to
135 * its 802.1q-designated place.
136 */
137 if (dsa_header[1] & 0x01)
138 new_header[2] |= 0x10;
139
140 /*
141 * Update packet checksum if skb is CHECKSUM_COMPLETE.
142 */
143 if (skb->ip_summed == CHECKSUM_COMPLETE) {
144 __wsum c = skb->csum;
145 c = csum_add(c, csum_partial(new_header + 2, 2, 0));
146 c = csum_sub(c, csum_partial(dsa_header + 2, 2, 0));
147 skb->csum = c;
148 }
149
150 memcpy(dsa_header, new_header, DSA_HLEN);
151 } else {
152 /*
153 * Remove DSA tag and update checksum.
154 */
155 skb_pull_rcsum(skb, DSA_HLEN);
156 memmove(skb->data - ETH_HLEN,
157 skb->data - ETH_HLEN - DSA_HLEN,
158 2 * ETH_ALEN);
159 }
160
161 skb->dev = ds->ports[source_port].netdev;
162
163 return skb;
164
165out_drop:
166 return NULL;
167}
168
169const struct dsa_device_ops dsa_netdev_ops = {
170 .xmit = dsa_xmit,
171 .rcv = dsa_rcv,
172};