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1/*
2 * vcan.c - Virtual CAN interface
3 *
4 * Copyright (c) 2002-2017 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 */
41
42#include <linux/module.h>
43#include <linux/init.h>
44#include <linux/netdevice.h>
45#include <linux/if_arp.h>
46#include <linux/if_ether.h>
47#include <linux/can.h>
48#include <linux/can/dev.h>
49#include <linux/can/skb.h>
50#include <linux/slab.h>
51#include <net/rtnetlink.h>
52
53#define DRV_NAME "vcan"
54
55MODULE_DESCRIPTION("virtual CAN interface");
56MODULE_LICENSE("Dual BSD/GPL");
57MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>");
58MODULE_ALIAS_RTNL_LINK(DRV_NAME);
59
60
61/*
62 * CAN test feature:
63 * Enable the echo on driver level for testing the CAN core echo modes.
64 * See Documentation/networking/can.rst for details.
65 */
66
67static bool echo; /* echo testing. Default: 0 (Off) */
68module_param(echo, bool, 0444);
69MODULE_PARM_DESC(echo, "Echo sent frames (for testing). Default: 0 (Off)");
70
71
72static void vcan_rx(struct sk_buff *skb, struct net_device *dev)
73{
74 struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
75 struct net_device_stats *stats = &dev->stats;
76
77 stats->rx_packets++;
78 stats->rx_bytes += cfd->len;
79
80 skb->pkt_type = PACKET_BROADCAST;
81 skb->dev = dev;
82 skb->ip_summed = CHECKSUM_UNNECESSARY;
83
84 netif_rx_ni(skb);
85}
86
87static netdev_tx_t vcan_tx(struct sk_buff *skb, struct net_device *dev)
88{
89 struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
90 struct net_device_stats *stats = &dev->stats;
91 int loop;
92
93 if (can_dropped_invalid_skb(dev, skb))
94 return NETDEV_TX_OK;
95
96 stats->tx_packets++;
97 stats->tx_bytes += cfd->len;
98
99 /* set flag whether this packet has to be looped back */
100 loop = skb->pkt_type == PACKET_LOOPBACK;
101
102 if (!echo) {
103 /* no echo handling available inside this driver */
104
105 if (loop) {
106 /*
107 * only count the packets here, because the
108 * CAN core already did the echo for us
109 */
110 stats->rx_packets++;
111 stats->rx_bytes += cfd->len;
112 }
113 consume_skb(skb);
114 return NETDEV_TX_OK;
115 }
116
117 /* perform standard echo handling for CAN network interfaces */
118
119 if (loop) {
120
121 skb = can_create_echo_skb(skb);
122 if (!skb)
123 return NETDEV_TX_OK;
124
125 /* receive with packet counting */
126 vcan_rx(skb, dev);
127 } else {
128 /* no looped packets => no counting */
129 consume_skb(skb);
130 }
131 return NETDEV_TX_OK;
132}
133
134static int vcan_change_mtu(struct net_device *dev, int new_mtu)
135{
136 /* Do not allow changing the MTU while running */
137 if (dev->flags & IFF_UP)
138 return -EBUSY;
139
140 if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU)
141 return -EINVAL;
142
143 dev->mtu = new_mtu;
144 return 0;
145}
146
147static const struct net_device_ops vcan_netdev_ops = {
148 .ndo_start_xmit = vcan_tx,
149 .ndo_change_mtu = vcan_change_mtu,
150};
151
152static void vcan_setup(struct net_device *dev)
153{
154 dev->type = ARPHRD_CAN;
155 dev->mtu = CANFD_MTU;
156 dev->hard_header_len = 0;
157 dev->addr_len = 0;
158 dev->tx_queue_len = 0;
159 dev->flags = IFF_NOARP;
160
161 /* set flags according to driver capabilities */
162 if (echo)
163 dev->flags |= IFF_ECHO;
164
165 dev->netdev_ops = &vcan_netdev_ops;
166 dev->needs_free_netdev = true;
167}
168
169static struct rtnl_link_ops vcan_link_ops __read_mostly = {
170 .kind = DRV_NAME,
171 .setup = vcan_setup,
172};
173
174static __init int vcan_init_module(void)
175{
176 pr_info("vcan: Virtual CAN interface driver\n");
177
178 if (echo)
179 printk(KERN_INFO "vcan: enabled echo on driver level.\n");
180
181 return rtnl_link_register(&vcan_link_ops);
182}
183
184static __exit void vcan_cleanup_module(void)
185{
186 rtnl_link_unregister(&vcan_link_ops);
187}
188
189module_init(vcan_init_module);
190module_exit(vcan_cleanup_module);
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 */
41
42#include <linux/module.h>
43#include <linux/init.h>
44#include <linux/netdevice.h>
45#include <linux/if_arp.h>
46#include <linux/if_ether.h>
47#include <linux/can.h>
48#include <linux/can/dev.h>
49#include <linux/slab.h>
50#include <net/rtnetlink.h>
51
52static __initdata const char banner[] =
53 KERN_INFO "vcan: Virtual CAN interface driver\n";
54
55MODULE_DESCRIPTION("virtual CAN interface");
56MODULE_LICENSE("Dual BSD/GPL");
57MODULE_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
66static bool echo; /* echo testing. Default: 0 (Off) */
67module_param(echo, bool, S_IRUGO);
68MODULE_PARM_DESC(echo, "Echo sent frames (for testing). Default: 0 (Off)");
69
70
71static void vcan_rx(struct sk_buff *skb, struct net_device *dev)
72{
73 struct can_frame *cf = (struct can_frame *)skb->data;
74 struct net_device_stats *stats = &dev->stats;
75
76 stats->rx_packets++;
77 stats->rx_bytes += cf->can_dlc;
78
79 skb->protocol = htons(ETH_P_CAN);
80 skb->pkt_type = PACKET_BROADCAST;
81 skb->dev = dev;
82 skb->ip_summed = CHECKSUM_UNNECESSARY;
83
84 netif_rx_ni(skb);
85}
86
87static netdev_tx_t vcan_tx(struct sk_buff *skb, struct net_device *dev)
88{
89 struct can_frame *cf = (struct can_frame *)skb->data;
90 struct net_device_stats *stats = &dev->stats;
91 int loop;
92
93 if (can_dropped_invalid_skb(dev, skb))
94 return NETDEV_TX_OK;
95
96 stats->tx_packets++;
97 stats->tx_bytes += cf->can_dlc;
98
99 /* set flag whether this packet has to be looped back */
100 loop = skb->pkt_type == PACKET_LOOPBACK;
101
102 if (!echo) {
103 /* no echo handling available inside this driver */
104
105 if (loop) {
106 /*
107 * only count the packets here, because the
108 * CAN core already did the echo for us
109 */
110 stats->rx_packets++;
111 stats->rx_bytes += cf->can_dlc;
112 }
113 kfree_skb(skb);
114 return NETDEV_TX_OK;
115 }
116
117 /* perform standard echo handling for CAN network interfaces */
118
119 if (loop) {
120 struct sock *srcsk = skb->sk;
121
122 skb = skb_share_check(skb, GFP_ATOMIC);
123 if (!skb)
124 return NETDEV_TX_OK;
125
126 /* receive with packet counting */
127 skb->sk = srcsk;
128 vcan_rx(skb, dev);
129 } else {
130 /* no looped packets => no counting */
131 kfree_skb(skb);
132 }
133 return NETDEV_TX_OK;
134}
135
136static const struct net_device_ops vcan_netdev_ops = {
137 .ndo_start_xmit = vcan_tx,
138};
139
140static void vcan_setup(struct net_device *dev)
141{
142 dev->type = ARPHRD_CAN;
143 dev->mtu = sizeof(struct can_frame);
144 dev->hard_header_len = 0;
145 dev->addr_len = 0;
146 dev->tx_queue_len = 0;
147 dev->flags = IFF_NOARP;
148
149 /* set flags according to driver capabilities */
150 if (echo)
151 dev->flags |= IFF_ECHO;
152
153 dev->netdev_ops = &vcan_netdev_ops;
154 dev->destructor = free_netdev;
155}
156
157static struct rtnl_link_ops vcan_link_ops __read_mostly = {
158 .kind = "vcan",
159 .setup = vcan_setup,
160};
161
162static __init int vcan_init_module(void)
163{
164 printk(banner);
165
166 if (echo)
167 printk(KERN_INFO "vcan: enabled echo on driver level.\n");
168
169 return rtnl_link_register(&vcan_link_ops);
170}
171
172static __exit void vcan_cleanup_module(void)
173{
174 rtnl_link_unregister(&vcan_link_ops);
175}
176
177module_init(vcan_init_module);
178module_exit(vcan_cleanup_module);