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