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 55 MODULE_DESCRIPTION("virtual CAN interface"); 56 MODULE_LICENSE("Dual BSD/GPL"); 57 MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>"); 58 MODULE_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 67 static bool echo; /* echo testing. Default: 0 (Off) */ 68 module_param(echo, bool, 0444); 69 MODULE_PARM_DESC(echo, "Echo sent frames (for testing). Default: 0 (Off)"); 70 71 72 static 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 87 static 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 } 133 134 static 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 } 146 147 static const struct net_device_ops vcan_netdev_ops = { 148 .ndo_start_xmit = vcan_tx, 149 .ndo_change_mtu = vcan_change_mtu, 150 }; 151 152 static 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 } 168 169 static struct rtnl_link_ops vcan_link_ops __read_mostly = { 170 .kind = DRV_NAME, 171 .setup = vcan_setup, 172 }; 173 174 static __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 } 183 184 static __exit void vcan_cleanup_module(void) 185 { 186 rtnl_link_unregister(&vcan_link_ops); 187 } 188 189 module_init(vcan_init_module); 190 module_exit(vcan_cleanup_module); 191