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/ethtool.h> 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/can-ml.h> 51 #include <linux/can/dev.h> 52 #include <linux/can/skb.h> 53 #include <linux/slab.h> 54 #include <net/rtnetlink.h> 55 56 #define DRV_NAME "vcan" 57 58 MODULE_DESCRIPTION("virtual CAN interface"); 59 MODULE_LICENSE("Dual BSD/GPL"); 60 MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>"); 61 MODULE_ALIAS_RTNL_LINK(DRV_NAME); 62 63 /* CAN test feature: 64 * Enable the echo on driver level for testing the CAN core echo modes. 65 * See Documentation/networking/can.rst for details. 66 */ 67 68 static bool echo; /* echo testing. Default: 0 (Off) */ 69 module_param(echo, bool, 0444); 70 MODULE_PARM_DESC(echo, "Echo sent frames (for testing). Default: 0 (Off)"); 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(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, len; 92 93 if (can_dropped_invalid_skb(dev, skb)) 94 return NETDEV_TX_OK; 95 96 len = cfd->can_id & CAN_RTR_FLAG ? 0 : cfd->len; 97 stats->tx_packets++; 98 stats->tx_bytes += len; 99 100 /* set flag whether this packet has to be looped back */ 101 loop = skb->pkt_type == PACKET_LOOPBACK; 102 103 skb_tx_timestamp(skb); 104 105 if (!echo) { 106 /* no echo handling available inside this driver */ 107 if (loop) { 108 /* only count the packets here, because the 109 * CAN core already did the echo for us 110 */ 111 stats->rx_packets++; 112 stats->rx_bytes += len; 113 } 114 consume_skb(skb); 115 return NETDEV_TX_OK; 116 } 117 118 /* perform standard echo handling for CAN network interfaces */ 119 120 if (loop) { 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 const struct ethtool_ops vcan_ethtool_ops = { 153 .get_ts_info = ethtool_op_get_ts_info, 154 }; 155 156 static void vcan_setup(struct net_device *dev) 157 { 158 dev->type = ARPHRD_CAN; 159 dev->mtu = CANFD_MTU; 160 dev->hard_header_len = 0; 161 dev->addr_len = 0; 162 dev->tx_queue_len = 0; 163 dev->flags = IFF_NOARP; 164 can_set_ml_priv(dev, netdev_priv(dev)); 165 166 /* set flags according to driver capabilities */ 167 if (echo) 168 dev->flags |= IFF_ECHO; 169 170 dev->netdev_ops = &vcan_netdev_ops; 171 dev->ethtool_ops = &vcan_ethtool_ops; 172 dev->needs_free_netdev = true; 173 } 174 175 static struct rtnl_link_ops vcan_link_ops __read_mostly = { 176 .kind = DRV_NAME, 177 .priv_size = sizeof(struct can_ml_priv), 178 .setup = vcan_setup, 179 }; 180 181 static __init int vcan_init_module(void) 182 { 183 pr_info("Virtual CAN interface driver\n"); 184 185 if (echo) 186 pr_info("enabled echo on driver level.\n"); 187 188 return rtnl_link_register(&vcan_link_ops); 189 } 190 191 static __exit void vcan_cleanup_module(void) 192 { 193 rtnl_link_unregister(&vcan_link_ops); 194 } 195 196 module_init(vcan_init_module); 197 module_exit(vcan_cleanup_module); 198