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Linux/drivers/net/can/vcan.c

  1 /*
  2  * vcan.c - Virtual CAN interface
  3  *
  4  * Copyright (c) 2002-2007 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 MODULE_DESCRIPTION("virtual CAN interface");
 54 MODULE_LICENSE("Dual BSD/GPL");
 55 MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>");
 56 
 57 
 58 /*
 59  * CAN test feature:
 60  * Enable the echo on driver level for testing the CAN core echo modes.
 61  * See Documentation/networking/can.txt for details.
 62  */
 63 
 64 static bool echo; /* echo testing. Default: 0 (Off) */
 65 module_param(echo, bool, S_IRUGO);
 66 MODULE_PARM_DESC(echo, "Echo sent frames (for testing). Default: 0 (Off)");
 67 
 68 
 69 static void vcan_rx(struct sk_buff *skb, struct net_device *dev)
 70 {
 71         struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
 72         struct net_device_stats *stats = &dev->stats;
 73 
 74         stats->rx_packets++;
 75         stats->rx_bytes += cfd->len;
 76 
 77         skb->pkt_type  = PACKET_BROADCAST;
 78         skb->dev       = dev;
 79         skb->ip_summed = CHECKSUM_UNNECESSARY;
 80 
 81         netif_rx_ni(skb);
 82 }
 83 
 84 static netdev_tx_t vcan_tx(struct sk_buff *skb, struct net_device *dev)
 85 {
 86         struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
 87         struct net_device_stats *stats = &dev->stats;
 88         int loop;
 89 
 90         if (can_dropped_invalid_skb(dev, skb))
 91                 return NETDEV_TX_OK;
 92 
 93         stats->tx_packets++;
 94         stats->tx_bytes += cfd->len;
 95 
 96         /* set flag whether this packet has to be looped back */
 97         loop = skb->pkt_type == PACKET_LOOPBACK;
 98 
 99         if (!echo) {
100                 /* no echo handling available inside this driver */
101 
102                 if (loop) {
103                         /*
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 
118                 skb = can_create_echo_skb(skb);
119                 if (!skb)
120                         return NETDEV_TX_OK;
121 
122                 /* receive with packet counting */
123                 vcan_rx(skb, dev);
124         } else {
125                 /* no looped packets => no counting */
126                 consume_skb(skb);
127         }
128         return NETDEV_TX_OK;
129 }
130 
131 static int vcan_change_mtu(struct net_device *dev, int new_mtu)
132 {
133         /* Do not allow changing the MTU while running */
134         if (dev->flags & IFF_UP)
135                 return -EBUSY;
136 
137         if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU)
138                 return -EINVAL;
139 
140         dev->mtu = new_mtu;
141         return 0;
142 }
143 
144 static const struct net_device_ops vcan_netdev_ops = {
145         .ndo_start_xmit = vcan_tx,
146         .ndo_change_mtu = vcan_change_mtu,
147 };
148 
149 static void vcan_setup(struct net_device *dev)
150 {
151         dev->type               = ARPHRD_CAN;
152         dev->mtu                = CAN_MTU;
153         dev->hard_header_len    = 0;
154         dev->addr_len           = 0;
155         dev->tx_queue_len       = 0;
156         dev->flags              = IFF_NOARP;
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->destructor         = free_netdev;
164 }
165 
166 static struct rtnl_link_ops vcan_link_ops __read_mostly = {
167         .kind   = "vcan",
168         .setup  = vcan_setup,
169 };
170 
171 static __init int vcan_init_module(void)
172 {
173         pr_info("vcan: Virtual CAN interface driver\n");
174 
175         if (echo)
176                 printk(KERN_INFO "vcan: enabled echo on driver level.\n");
177 
178         return rtnl_link_register(&vcan_link_ops);
179 }
180 
181 static __exit void vcan_cleanup_module(void)
182 {
183         rtnl_link_unregister(&vcan_link_ops);
184 }
185 
186 module_init(vcan_init_module);
187 module_exit(vcan_cleanup_module);
188 

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