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