/*
* vcan.c - Virtual CAN interface
*
* Copyright (c) 2002-2007 Volkswagen Group Electronic Research
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of Volkswagen nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* Alternatively, provided that this notice is retained in full, this
* software may be distributed under the terms of the GNU General
* Public License ("GPL") version 2, in which case the provisions of the
* GPL apply INSTEAD OF those given above.
*
* The provided data structures and external interfaces from this code
* are not restricted to be used by modules with a GPL compatible license.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
* DAMAGE.
*
* Send feedback to <socketcan-users@lists.berlios.de>
*
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/if_arp.h>
#include <linux/if_ether.h>
#include <linux/can.h>
#include <net/rtnetlink.h>
static __initdata const char banner[] =
KERN_INFO "vcan: Virtual CAN interface driver\n";
MODULE_DESCRIPTION("virtual CAN interface");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>");
/*
* CAN test feature:
* Enable the echo on driver level for testing the CAN core echo modes.
* See Documentation/networking/can.txt for details.
*/
static int echo; /* echo testing. Default: 0 (Off) */
module_param(echo, bool, S_IRUGO);
MODULE_PARM_DESC(echo, "Echo sent frames (for testing). Default: 0 (Off)");
static void vcan_rx(struct sk_buff *skb, struct net_device *dev)
{
struct net_device_stats *stats = &dev->stats;
stats->rx_packets++;
stats->rx_bytes += skb->len;
skb->protocol = htons(ETH_P_CAN);
skb->pkt_type = PACKET_BROADCAST;
skb->dev = dev;
skb->ip_summed = CHECKSUM_UNNECESSARY;
netif_rx(skb);
}
static netdev_tx_t vcan_tx(struct sk_buff *skb, struct net_device *dev)
{
struct net_device_stats *stats = &dev->stats;
int loop;
stats->tx_packets++;
stats->tx_bytes += skb->len;
/* set flag whether this packet has to be looped back */
loop = skb->pkt_type == PACKET_LOOPBACK;
if (!echo) {
/* no echo handling available inside this driver */
if (loop) {
/*
* only count the packets here, because the
* CAN core already did the echo for us
*/
stats->rx_packets++;
stats->rx_bytes += skb->len;
}
kfree_skb(skb);
return NETDEV_TX_OK;
}
/* perform standard echo handling for CAN network interfaces */
if (loop) {
struct sock *srcsk = skb->sk;
skb = skb_share_check(skb, GFP_ATOMIC);
if (!skb)
return NETDEV_TX_OK;
/* receive with packet counting */
skb->sk = srcsk;
vcan_rx(skb, dev);
} else {
/* no looped packets => no counting */
kfree_skb(skb);
}
return NETDEV_TX_OK;
}
static const struct net_device_ops vcan_netdev_ops = {
.ndo_start_xmit = vcan_tx,
};
static void vcan_setup(struct net_device *dev)
{
dev->type = ARPHRD_CAN;
dev->mtu = sizeof(struct can_frame);
dev->hard_header_len = 0;
dev->addr_len = 0;
dev->tx_queue_len = 0;
dev->flags = IFF_NOARP;
/* set flags according to driver capabilities */
if (echo)
dev->flags |= IFF_ECHO;
dev->netdev_ops = &vcan_netdev_ops;
dev->destructor = free_netdev;
}
static struct rtnl_link_ops vcan_link_ops __read_mostly = {
.kind = "vcan",
.setup = vcan_setup,
};
static __init int vcan_init_module(void)
{
printk(banner);
if (echo)
printk(KERN_INFO "vcan: enabled echo on driver level.\n");
return rtnl_link_register(&vcan_link_ops);
}
static __exit void vcan_cleanup_module(void)
{
rtnl_link_unregister(&vcan_link_ops);
}
module_init(vcan_init_module);
module_exit(vcan_cleanup_module);
