LXR linux/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
  57MODULE_DESCRIPTION("virtual CAN interface");
  58MODULE_LICENSE("Dual BSD/GPL");
  59MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>");
  60MODULE_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
  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
  71static 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
  86static 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
 130static 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
 143static const struct net_device_ops vcan_netdev_ops = {
 144        .ndo_start_xmit = vcan_tx,
 145        .ndo_change_mtu = vcan_change_mtu,
 146};
 147
 148static 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
 166static 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
 172static __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
 182static __exit void vcan_cleanup_module(void)
 183{
 184        rtnl_link_unregister(&vcan_link_ops);
 185}
 186
 187module_init(vcan_init_module);
 188module_exit(vcan_cleanup_module);
 189