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ccb29637 OH |
1 | /* |
2 | * vcan.c - Virtual CAN interface | |
3 | * | |
4 | * Copyright (c) 2002-2007 Volkswagen Group Electronic Research | |
5 | * All rights reserved. | |
6 | * | |
7 | * Redistribution and use in source and binary forms, with or without | |
8 | * modification, are permitted provided that the following conditions | |
9 | * are met: | |
10 | * 1. Redistributions of source code must retain the above copyright | |
11 | * notice, this list of conditions and the following disclaimer. | |
12 | * 2. Redistributions in binary form must reproduce the above copyright | |
13 | * notice, this list of conditions and the following disclaimer in the | |
14 | * documentation and/or other materials provided with the distribution. | |
15 | * 3. Neither the name of Volkswagen nor the names of its contributors | |
16 | * may be used to endorse or promote products derived from this software | |
17 | * without specific prior written permission. | |
18 | * | |
19 | * Alternatively, provided that this notice is retained in full, this | |
20 | * software may be distributed under the terms of the GNU General | |
21 | * Public License ("GPL") version 2, in which case the provisions of the | |
22 | * GPL apply INSTEAD OF those given above. | |
23 | * | |
24 | * The provided data structures and external interfaces from this code | |
25 | * are not restricted to be used by modules with a GPL compatible license. | |
26 | * | |
27 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
28 | * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
29 | * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | |
30 | * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT | |
31 | * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
32 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | |
33 | * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
34 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
35 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
36 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | |
37 | * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH | |
38 | * DAMAGE. | |
39 | * | |
40 | * Send feedback to <socketcan-users@lists.berlios.de> | |
41 | * | |
42 | */ | |
43 | ||
44 | #include <linux/module.h> | |
45 | #include <linux/init.h> | |
46 | #include <linux/netdevice.h> | |
47 | #include <linux/if_arp.h> | |
48 | #include <linux/if_ether.h> | |
49 | #include <linux/can.h> | |
50 | #include <net/rtnetlink.h> | |
51 | ||
52 | static __initdata const char banner[] = | |
53 | KERN_INFO "vcan: Virtual CAN interface driver\n"; | |
54 | ||
55 | MODULE_DESCRIPTION("virtual CAN interface"); | |
56 | MODULE_LICENSE("Dual BSD/GPL"); | |
57 | MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>"); | |
58 | ||
59 | ||
60 | /* | |
61 | * CAN test feature: | |
62 | * Enable the echo on driver level for testing the CAN core echo modes. | |
63 | * See Documentation/networking/can.txt for details. | |
64 | */ | |
65 | ||
66 | static int echo; /* echo testing. Default: 0 (Off) */ | |
67 | module_param(echo, bool, S_IRUGO); | |
68 | MODULE_PARM_DESC(echo, "Echo sent frames (for testing). Default: 0 (Off)"); | |
69 | ||
70 | ||
71 | static void vcan_rx(struct sk_buff *skb, struct net_device *dev) | |
72 | { | |
73 | struct net_device_stats *stats = &dev->stats; | |
74 | ||
75 | stats->rx_packets++; | |
76 | stats->rx_bytes += skb->len; | |
77 | ||
78 | skb->protocol = htons(ETH_P_CAN); | |
79 | skb->pkt_type = PACKET_BROADCAST; | |
80 | skb->dev = dev; | |
81 | skb->ip_summed = CHECKSUM_UNNECESSARY; | |
82 | ||
83 | netif_rx(skb); | |
84 | } | |
85 | ||
424efe9c | 86 | static netdev_tx_t vcan_tx(struct sk_buff *skb, struct net_device *dev) |
ccb29637 OH |
87 | { |
88 | struct net_device_stats *stats = &dev->stats; | |
89 | int loop; | |
90 | ||
91 | stats->tx_packets++; | |
92 | stats->tx_bytes += skb->len; | |
93 | ||
94 | /* set flag whether this packet has to be looped back */ | |
95 | loop = skb->pkt_type == PACKET_LOOPBACK; | |
96 | ||
97 | if (!echo) { | |
98 | /* no echo handling available inside this driver */ | |
99 | ||
100 | if (loop) { | |
101 | /* | |
102 | * only count the packets here, because the | |
103 | * CAN core already did the echo for us | |
104 | */ | |
105 | stats->rx_packets++; | |
106 | stats->rx_bytes += skb->len; | |
107 | } | |
108 | kfree_skb(skb); | |
109 | return NETDEV_TX_OK; | |
110 | } | |
111 | ||
112 | /* perform standard echo handling for CAN network interfaces */ | |
113 | ||
114 | if (loop) { | |
115 | struct sock *srcsk = skb->sk; | |
116 | ||
117 | skb = skb_share_check(skb, GFP_ATOMIC); | |
118 | if (!skb) | |
119 | return NETDEV_TX_OK; | |
120 | ||
121 | /* receive with packet counting */ | |
122 | skb->sk = srcsk; | |
123 | vcan_rx(skb, dev); | |
124 | } else { | |
125 | /* no looped packets => no counting */ | |
126 | kfree_skb(skb); | |
127 | } | |
128 | return NETDEV_TX_OK; | |
129 | } | |
130 | ||
5ad258c0 OH |
131 | static const struct net_device_ops vcan_netdev_ops = { |
132 | .ndo_start_xmit = vcan_tx, | |
133 | }; | |
134 | ||
ccb29637 OH |
135 | static void vcan_setup(struct net_device *dev) |
136 | { | |
fc10af8e OH |
137 | dev->type = ARPHRD_CAN; |
138 | dev->mtu = sizeof(struct can_frame); | |
139 | dev->hard_header_len = 0; | |
140 | dev->addr_len = 0; | |
141 | dev->tx_queue_len = 0; | |
142 | dev->flags = IFF_NOARP; | |
ccb29637 OH |
143 | |
144 | /* set flags according to driver capabilities */ | |
145 | if (echo) | |
146 | dev->flags |= IFF_ECHO; | |
147 | ||
fc10af8e OH |
148 | dev->netdev_ops = &vcan_netdev_ops; |
149 | dev->destructor = free_netdev; | |
ccb29637 OH |
150 | } |
151 | ||
152 | static struct rtnl_link_ops vcan_link_ops __read_mostly = { | |
fc10af8e OH |
153 | .kind = "vcan", |
154 | .setup = vcan_setup, | |
ccb29637 OH |
155 | }; |
156 | ||
157 | static __init int vcan_init_module(void) | |
158 | { | |
159 | printk(banner); | |
160 | ||
161 | if (echo) | |
162 | printk(KERN_INFO "vcan: enabled echo on driver level.\n"); | |
163 | ||
164 | return rtnl_link_register(&vcan_link_ops); | |
165 | } | |
166 | ||
167 | static __exit void vcan_cleanup_module(void) | |
168 | { | |
169 | rtnl_link_unregister(&vcan_link_ops); | |
170 | } | |
171 | ||
172 | module_init(vcan_init_module); | |
173 | module_exit(vcan_cleanup_module); |