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
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 return NULL;
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 return NULL;
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}
66
67static struct sk_buff *dsa_rcv(struct sk_buff *skb, struct net_device *dev,
68 struct packet_type *pt)
69{
70 struct dsa_switch_tree *dst = dev->dsa_ptr;
71 struct dsa_switch *ds;
72 u8 *dsa_header;
73 int source_device;
74 int source_port;
75
76 if (unlikely(!pskb_may_pull(skb, DSA_HLEN)))
77 return NULL;
78
79 /*
80 * The ethertype field is part of the DSA header.
81 */
82 dsa_header = skb->data - 2;
83
84 /*
85 * Check that frame type is either TO_CPU or FORWARD.
86 */
87 if ((dsa_header[0] & 0xc0) != 0x00 && (dsa_header[0] & 0xc0) != 0xc0)
88 return NULL;
89
90 /*
91 * Determine source device and port.
92 */
93 source_device = dsa_header[0] & 0x1f;
94 source_port = (dsa_header[1] >> 3) & 0x1f;
95
96 /*
97 * Check that the source device exists and that the source
98 * port is a registered DSA port.
99 */
100 if (source_device >= DSA_MAX_SWITCHES)
101 return NULL;
102
103 ds = dst->ds[source_device];
104 if (!ds)
105 return NULL;
106
107 if (source_port >= ds->num_ports || !ds->ports[source_port].netdev)
108 return NULL;
109
110 /*
111 * Convert the DSA header to an 802.1q header if the 'tagged'
112 * bit in the DSA header is set. If the 'tagged' bit is clear,
113 * delete the DSA header entirely.
114 */
115 if (dsa_header[0] & 0x20) {
116 u8 new_header[4];
117
118 /*
119 * Insert 802.1q ethertype and copy the VLAN-related
120 * fields, but clear the bit that will hold CFI (since
121 * DSA uses that bit location for another purpose).
122 */
123 new_header[0] = (ETH_P_8021Q >> 8) & 0xff;
124 new_header[1] = ETH_P_8021Q & 0xff;
125 new_header[2] = dsa_header[2] & ~0x10;
126 new_header[3] = dsa_header[3];
127
128 /*
129 * Move CFI bit from its place in the DSA header to
130 * its 802.1q-designated place.
131 */
132 if (dsa_header[1] & 0x01)
133 new_header[2] |= 0x10;
134
135 /*
136 * Update packet checksum if skb is CHECKSUM_COMPLETE.
137 */
138 if (skb->ip_summed == CHECKSUM_COMPLETE) {
139 __wsum c = skb->csum;
140 c = csum_add(c, csum_partial(new_header + 2, 2, 0));
141 c = csum_sub(c, csum_partial(dsa_header + 2, 2, 0));
142 skb->csum = c;
143 }
144
145 memcpy(dsa_header, new_header, DSA_HLEN);
146 } else {
147 /*
148 * Remove DSA tag and update checksum.
149 */
150 skb_pull_rcsum(skb, DSA_HLEN);
151 memmove(skb->data - ETH_HLEN,
152 skb->data - ETH_HLEN - DSA_HLEN,
153 2 * ETH_ALEN);
154 }
155
156 skb->dev = ds->ports[source_port].netdev;
157
158 return skb;
159}
160
161const struct dsa_device_ops dsa_netdev_ops = {
162 .xmit = dsa_xmit,
163 .rcv = dsa_rcv,
164};