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 52 static __initconst 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 bool 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 canfd_frame *cfd = (struct canfd_frame *)skb->data; 74 struct net_device_stats *stats = &dev->stats; 75 76 stats->rx_packets++; 77 stats->rx_bytes += cfd->len; 78 79 skb->pkt_type = PACKET_BROADCAST; 80 skb->dev = dev; 81 skb->ip_summed = CHECKSUM_UNNECESSARY; 82 83 netif_rx_ni(skb); 84 } 85 86 static netdev_tx_t vcan_tx(struct sk_buff *skb, struct net_device *dev) 87 { 88 struct canfd_frame *cfd = (struct canfd_frame *)skb->data; 89 struct net_device_stats *stats = &dev->stats; 90 int loop; 91 92 if (can_dropped_invalid_skb(dev, skb)) 93 return NETDEV_TX_OK; 94 95 stats->tx_packets++; 96 stats->tx_bytes += cfd->len; 97 98 /* set flag whether this packet has to be looped back */ 99 loop = skb->pkt_type == PACKET_LOOPBACK; 100 101 if (!echo) { 102 /* no echo handling available inside this driver */ 103 104 if (loop) { 105 /* 106 * only count the packets here, because the 107 * CAN core already did the echo for us 108 */ 109 stats->rx_packets++; 110 stats->rx_bytes += cfd->len; 111 } 112 kfree_skb(skb); 113 return NETDEV_TX_OK; 114 } 115 116 /* perform standard echo handling for CAN network interfaces */ 117 118 if (loop) { 119 struct sock *srcsk = skb->sk; 120 121 skb = skb_share_check(skb, GFP_ATOMIC); 122 if (!skb) 123 return NETDEV_TX_OK; 124 125 /* receive with packet counting */ 126 skb->sk = srcsk; 127 vcan_rx(skb, dev); 128 } else { 129 /* no looped packets => no counting */ 130 kfree_skb(skb); 131 } 132 return NETDEV_TX_OK; 133 } 134 135 static int vcan_change_mtu(struct net_device *dev, int new_mtu) 136 { 137 /* Do not allow changing the MTU while running */ 138 if (dev->flags & IFF_UP) 139 return -EBUSY; 140 141 if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU) 142 return -EINVAL; 143 144 dev->mtu = new_mtu; 145 return 0; 146 } 147 148 static const struct net_device_ops vcan_netdev_ops = { 149 .ndo_start_xmit = vcan_tx, 150 .ndo_change_mtu = vcan_change_mtu, 151 }; 152 153 static void vcan_setup(struct net_device *dev) 154 { 155 dev->type = ARPHRD_CAN; 156 dev->mtu = CAN_MTU; 157 dev->hard_header_len = 0; 158 dev->addr_len = 0; 159 dev->tx_queue_len = 0; 160 dev->flags = IFF_NOARP; 161 162 /* set flags according to driver capabilities */ 163 if (echo) 164 dev->flags |= IFF_ECHO; 165 166 dev->netdev_ops = &vcan_netdev_ops; 167 dev->destructor = free_netdev; 168 } 169 170 static struct rtnl_link_ops vcan_link_ops __read_mostly = { 171 .kind = "vcan", 172 .setup = vcan_setup, 173 }; 174 175 static __init int vcan_init_module(void) 176 { 177 printk(banner); 178 179 if (echo) 180 printk(KERN_INFO "vcan: enabled echo on driver level.\n"); 181 182 return rtnl_link_register(&vcan_link_ops); 183 } 184 185 static __exit void vcan_cleanup_module(void) 186 { 187 rtnl_link_unregister(&vcan_link_ops); 188 } 189 190 module_init(vcan_init_module); 191 module_exit(vcan_cleanup_module); 192