drivers/net/can/vcan.c

   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_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                 if (loop) {
 104                         /* only count the packets here, because the
 105                          * CAN core already did the echo for us
 106                          */
 107                         stats->rx_packets++;
 108                         stats->rx_bytes += cfd->len;
 109                 }
 110                 consume_skb(skb);
 111                 return NETDEV_TX_OK;
 112         }
 113
 114         /* perform standard echo handling for CAN network interfaces */
 115
 116         if (loop) {
 117                 skb = can_create_echo_skb(skb);
 118                 if (!skb)
 119                         return NETDEV_TX_OK;
 120
 121                 /* receive with packet counting */
 122                 vcan_rx(skb, dev);
 123         } else {
 124                 /* no looped packets => no counting */
 125                 consume_skb(skb);
 126         }
 127         return NETDEV_TX_OK;
 128 }
 129
 130 static int vcan_change_mtu(struct net_device *dev, int new_mtu)
 131 {
 132         /* Do not allow changing the MTU while running */
 133         if (dev->flags & IFF_UP)
 134                 return -EBUSY;
 135
 136         if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU)
 137                 return -EINVAL;
 138
 139         dev->mtu = new_mtu;
 140         return 0;
 141 }
 142
 143 static const struct net_device_ops vcan_netdev_ops = {
 144         .ndo_start_xmit = vcan_tx,
 145         .ndo_change_mtu = vcan_change_mtu,
 146 };
 147
 148 static void vcan_setup(struct net_device *dev)
 149 {
 150         dev->type               = ARPHRD_CAN;
 151         dev->mtu                = CANFD_MTU;
 152         dev->hard_header_len    = 0;
 153         dev->addr_len           = 0;
 154         dev->tx_queue_len       = 0;
 155         dev->flags              = IFF_NOARP;
 156         dev->ml_priv            = netdev_priv(dev);
 157
 158         /* set flags according to driver capabilities */
 159         if (echo)
 160                 dev->flags |= IFF_ECHO;
 161
 162         dev->netdev_ops         = &vcan_netdev_ops;
 163         dev->needs_free_netdev  = true;
 164 }
 165
 166 static struct rtnl_link_ops vcan_link_ops __read_mostly = {
 167         .kind = DRV_NAME,
 168         .priv_size = sizeof(struct can_ml_priv),
 169         .setup = vcan_setup,
 170 };
 171
 172 static __init int vcan_init_module(void)
 173 {
 174         pr_info("Virtual CAN interface driver\n");
 175
 176         if (echo)
 177                 pr_info("enabled echo on driver level.\n");
 178
 179         return rtnl_link_register(&vcan_link_ops);
 180 }
 181
 182 static __exit void vcan_cleanup_module(void)
 183 {
 184         rtnl_link_unregister(&vcan_link_ops);
 185 }
 186
 187 module_init(vcan_init_module);
 188 module_exit(vcan_cleanup_module);