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/can-ml.h> 50 #include <linux/can/dev.h> 51 #include <linux/can/skb.h> 52 #include <linux/slab.h> 53 #include <net/rtnetlink.h> 54 55 #define DRV_NAME "vcan" 56 57 MODULE_DESCRIPTION("virtual CAN interface"); 58 MODULE_LICENSE("Dual BSD/GPL"); 59 MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>"); 60 MODULE_ALIAS_RTNL_LINK(DRV_NAME); 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 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(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, len; 91 92 if (can_dropped_invalid_skb(dev, skb)) 93 return NETDEV_TX_OK; 94 95 len = cfd->can_id & CAN_RTR_FLAG ? 0 : cfd->len; 96 stats->tx_packets++; 97 stats->tx_bytes += 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 if (loop) { 105 /* only count the packets here, because the 106 * CAN core already did the echo for us 107 */ 108 stats->rx_packets++; 109 stats->rx_bytes += len; 110 } 111 consume_skb(skb); 112 return NETDEV_TX_OK; 113 } 114 115 /* perform standard echo handling for CAN network interfaces */ 116 117 if (loop) { 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 = CANFD_MTU; 153 dev->hard_header_len = 0; 154 dev->addr_len = 0; 155 dev->tx_queue_len = 0; 156 dev->flags = IFF_NOARP; 157 can_set_ml_priv(dev, netdev_priv(dev)); 158 159 /* set flags according to driver capabilities */ 160 if (echo) 161 dev->flags |= IFF_ECHO; 162 163 dev->netdev_ops = &vcan_netdev_ops; 164 dev->needs_free_netdev = true; 165 } 166 167 static struct rtnl_link_ops vcan_link_ops __read_mostly = { 168 .kind = DRV_NAME, 169 .priv_size = sizeof(struct can_ml_priv), 170 .setup = vcan_setup, 171 }; 172 173 static __init int vcan_init_module(void) 174 { 175 pr_info("Virtual CAN interface driver\n"); 176 177 if (echo) 178 pr_info("enabled echo on driver level.\n"); 179 180 return rtnl_link_register(&vcan_link_ops); 181 } 182 183 static __exit void vcan_cleanup_module(void) 184 { 185 rtnl_link_unregister(&vcan_link_ops); 186 } 187 188 module_init(vcan_init_module); 189 module_exit(vcan_cleanup_module); 190