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 <linux/can/dev.h> 51 #include <linux/slab.h> 52 #include <net/rtnetlink.h> 53 54 static __initdata const char banner[] = 55 KERN_INFO "vcan: Virtual CAN interface driver\n"; 56 57 MODULE_DESCRIPTION("virtual CAN interface"); 58 MODULE_LICENSE("Dual BSD/GPL"); 59 MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>"); 60 61 62 /* 63 * CAN test feature: 64 * Enable the echo on driver level for testing the CAN core echo modes. 65 * See Documentation/networking/can.txt for details. 66 */ 67 68 static int echo; /* echo testing. Default: 0 (Off) */ 69 module_param(echo, bool, S_IRUGO); 70 MODULE_PARM_DESC(echo, "Echo sent frames (for testing). Default: 0 (Off)"); 71 72 73 static void vcan_rx(struct sk_buff *skb, struct net_device *dev) 74 { 75 struct can_frame *cf = (struct can_frame *)skb->data; 76 struct net_device_stats *stats = &dev->stats; 77 78 stats->rx_packets++; 79 stats->rx_bytes += cf->can_dlc; 80 81 skb->protocol = htons(ETH_P_CAN); 82 skb->pkt_type = PACKET_BROADCAST; 83 skb->dev = dev; 84 skb->ip_summed = CHECKSUM_UNNECESSARY; 85 86 netif_rx_ni(skb); 87 } 88 89 static netdev_tx_t vcan_tx(struct sk_buff *skb, struct net_device *dev) 90 { 91 struct can_frame *cf = (struct can_frame *)skb->data; 92 struct net_device_stats *stats = &dev->stats; 93 int loop; 94 95 if (can_dropped_invalid_skb(dev, skb)) 96 return NETDEV_TX_OK; 97 98 stats->tx_packets++; 99 stats->tx_bytes += cf->can_dlc; 100 101 /* set flag whether this packet has to be looped back */ 102 loop = skb->pkt_type == PACKET_LOOPBACK; 103 104 if (!echo) { 105 /* no echo handling available inside this driver */ 106 107 if (loop) { 108 /* 109 * only count the packets here, because the 110 * CAN core already did the echo for us 111 */ 112 stats->rx_packets++; 113 stats->rx_bytes += cf->can_dlc; 114 } 115 kfree_skb(skb); 116 return NETDEV_TX_OK; 117 } 118 119 /* perform standard echo handling for CAN network interfaces */ 120 121 if (loop) { 122 struct sock *srcsk = skb->sk; 123 124 skb = skb_share_check(skb, GFP_ATOMIC); 125 if (!skb) 126 return NETDEV_TX_OK; 127 128 /* receive with packet counting */ 129 skb->sk = srcsk; 130 vcan_rx(skb, dev); 131 } else { 132 /* no looped packets => no counting */ 133 kfree_skb(skb); 134 } 135 return NETDEV_TX_OK; 136 } 137 138 static const struct net_device_ops vcan_netdev_ops = { 139 .ndo_start_xmit = vcan_tx, 140 }; 141 142 static void vcan_setup(struct net_device *dev) 143 { 144 dev->type = ARPHRD_CAN; 145 dev->mtu = sizeof(struct can_frame); 146 dev->hard_header_len = 0; 147 dev->addr_len = 0; 148 dev->tx_queue_len = 0; 149 dev->flags = IFF_NOARP; 150 151 /* set flags according to driver capabilities */ 152 if (echo) 153 dev->flags |= IFF_ECHO; 154 155 dev->netdev_ops = &vcan_netdev_ops; 156 dev->destructor = free_netdev; 157 } 158 159 static struct rtnl_link_ops vcan_link_ops __read_mostly = { 160 .kind = "vcan", 161 .setup = vcan_setup, 162 }; 163 164 static __init int vcan_init_module(void) 165 { 166 printk(banner); 167 168 if (echo) 169 printk(KERN_INFO "vcan: enabled echo on driver level.\n"); 170 171 return rtnl_link_register(&vcan_link_ops); 172 } 173 174 static __exit void vcan_cleanup_module(void) 175 { 176 rtnl_link_unregister(&vcan_link_ops); 177 } 178 179 module_init(vcan_init_module); 180 module_exit(vcan_cleanup_module); 181