1 /* vcan.c - Virtual CAN interface 2 * 3 * Copyright (c) 2002-2017 Volkswagen Group Electronic Research 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Neither the name of Volkswagen nor the names of its contributors 15 * may be used to endorse or promote products derived from this software 16 * without specific prior written permission. 17 * 18 * Alternatively, provided that this notice is retained in full, this 19 * software may be distributed under the terms of the GNU General 20 * Public License ("GPL") version 2, in which case the provisions of the 21 * GPL apply INSTEAD OF those given above. 22 * 23 * The provided data structures and external interfaces from this code 24 * are not restricted to be used by modules with a GPL compatible license. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 27 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 28 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 29 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 30 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 31 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 32 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 36 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 37 * DAMAGE. 38 * 39 */ 40 41 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 42 43 #include <linux/module.h> 44 #include <linux/init.h> 45 #include <linux/netdevice.h> 46 #include <linux/if_arp.h> 47 #include <linux/if_ether.h> 48 #include <linux/can.h> 49 #include <linux/can/dev.h> 50 #include <linux/can/skb.h> 51 #include <linux/slab.h> 52 #include <net/rtnetlink.h> 53 54 #define DRV_NAME "vcan" 55 56 MODULE_DESCRIPTION("virtual CAN interface"); 57 MODULE_LICENSE("Dual BSD/GPL"); 58 MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>"); 59 MODULE_ALIAS_RTNL_LINK(DRV_NAME); 60 61 /* CAN test feature: 62 * Enable the echo on driver level for testing the CAN core echo modes. 63 * See Documentation/networking/can.rst for details. 64 */ 65 66 static bool echo; /* echo testing. Default: 0 (Off) */ 67 module_param(echo, bool, 0444); 68 MODULE_PARM_DESC(echo, "Echo sent frames (for testing). Default: 0 (Off)"); 69 70 static void vcan_rx(struct sk_buff *skb, struct net_device *dev) 71 { 72 struct canfd_frame *cfd = (struct canfd_frame *)skb->data; 73 struct net_device_stats *stats = &dev->stats; 74 75 stats->rx_packets++; 76 stats->rx_bytes += cfd->len; 77 78 skb->pkt_type = PACKET_BROADCAST; 79 skb->dev = dev; 80 skb->ip_summed = CHECKSUM_UNNECESSARY; 81 82 netif_rx_ni(skb); 83 } 84 85 static netdev_tx_t vcan_tx(struct sk_buff *skb, struct net_device *dev) 86 { 87 struct canfd_frame *cfd = (struct canfd_frame *)skb->data; 88 struct net_device_stats *stats = &dev->stats; 89 int loop; 90 91 if (can_dropped_invalid_skb(dev, skb)) 92 return NETDEV_TX_OK; 93 94 stats->tx_packets++; 95 stats->tx_bytes += cfd->len; 96 97 /* set flag whether this packet has to be looped back */ 98 loop = skb->pkt_type == PACKET_LOOPBACK; 99 100 if (!echo) { 101 /* no echo handling available inside this driver */ 102 if (loop) { 103 /* only count the packets here, because the 104 * CAN core already did the echo for us 105 */ 106 stats->rx_packets++; 107 stats->rx_bytes += cfd->len; 108 } 109 consume_skb(skb); 110 return NETDEV_TX_OK; 111 } 112 113 /* perform standard echo handling for CAN network interfaces */ 114 115 if (loop) { 116 skb = can_create_echo_skb(skb); 117 if (!skb) 118 return NETDEV_TX_OK; 119 120 /* receive with packet counting */ 121 vcan_rx(skb, dev); 122 } else { 123 /* no looped packets => no counting */ 124 consume_skb(skb); 125 } 126 return NETDEV_TX_OK; 127 } 128 129 static int vcan_change_mtu(struct net_device *dev, int new_mtu) 130 { 131 /* Do not allow changing the MTU while running */ 132 if (dev->flags & IFF_UP) 133 return -EBUSY; 134 135 if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU) 136 return -EINVAL; 137 138 dev->mtu = new_mtu; 139 return 0; 140 } 141 142 static const struct net_device_ops vcan_netdev_ops = { 143 .ndo_start_xmit = vcan_tx, 144 .ndo_change_mtu = vcan_change_mtu, 145 }; 146 147 static void vcan_setup(struct net_device *dev) 148 { 149 dev->type = ARPHRD_CAN; 150 dev->mtu = CANFD_MTU; 151 dev->hard_header_len = 0; 152 dev->addr_len = 0; 153 dev->tx_queue_len = 0; 154 dev->flags = IFF_NOARP; 155 156 /* set flags according to driver capabilities */ 157 if (echo) 158 dev->flags |= IFF_ECHO; 159 160 dev->netdev_ops = &vcan_netdev_ops; 161 dev->needs_free_netdev = true; 162 } 163 164 static struct rtnl_link_ops vcan_link_ops __read_mostly = { 165 .kind = DRV_NAME, 166 .setup = vcan_setup, 167 }; 168 169 static __init int vcan_init_module(void) 170 { 171 pr_info("Virtual CAN interface driver\n"); 172 173 if (echo) 174 pr_info("enabled echo on driver level.\n"); 175 176 return rtnl_link_register(&vcan_link_ops); 177 } 178 179 static __exit void vcan_cleanup_module(void) 180 { 181 rtnl_link_unregister(&vcan_link_ops); 182 } 183 184 module_init(vcan_init_module); 185 module_exit(vcan_cleanup_module); 186