diff options
Diffstat (limited to 'drivers/net/can/vcan.c')
| -rw-r--r-- | drivers/net/can/vcan.c | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/drivers/net/can/vcan.c b/drivers/net/can/vcan.c new file mode 100644 index 00000000000..103f0f1df28 --- /dev/null +++ b/drivers/net/can/vcan.c @@ -0,0 +1,169 @@ +/* + * 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 int 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 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->hard_start_xmit = vcan_tx; + 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); |