LXR linux/drivers/net/can/vcan.c

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