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/ethtool.h>
44#include <linux/module.h>
45#include <linux/init.h>
46#include <linux/netdevice.h>
47#include <linux/if_arp.h>
48#include <linux/if_ether.h>
49#include <linux/can.h>
50#include <linux/can/can-ml.h>
51#include <linux/can/dev.h>
52#include <linux/can/skb.h>
53#include <linux/slab.h>
54#include <net/rtnetlink.h>
55
56#define DRV_NAME "vcan"
57
58MODULE_DESCRIPTION("virtual CAN interface");
59MODULE_LICENSE("Dual BSD/GPL");
60MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>");
61MODULE_ALIAS_RTNL_LINK(DRV_NAME);
62
63/* CAN test feature:
64 * Enable the echo on driver level for testing the CAN core echo modes.
65 * See Documentation/networking/can.rst for details.
66 */
67
68static bool echo; /* echo testing. Default: 0 (Off) */
69module_param(echo, bool, 0444);
70MODULE_PARM_DESC(echo, "Echo sent frames (for testing). Default: 0 (Off)");
71
72static void vcan_rx(struct sk_buff *skb, struct net_device *dev)
73{
74	struct net_device_stats *stats = &dev->stats;
75
76	stats->rx_packets++;
77	stats->rx_bytes += can_skb_get_data_len(skb);
78
79	skb->pkt_type  = PACKET_BROADCAST;
80	skb->dev       = dev;
81	skb->ip_summed = CHECKSUM_UNNECESSARY;
82
83	netif_rx(skb);
84}
85
86static netdev_tx_t vcan_tx(struct sk_buff *skb, struct net_device *dev)
87{
88	struct net_device_stats *stats = &dev->stats;
89	unsigned int len;
90	int loop;
91
92	if (can_dropped_invalid_skb(dev, skb))
93		return NETDEV_TX_OK;
94
95	len = can_skb_get_data_len(skb);
96	stats->tx_packets++;
97	stats->tx_bytes += len;
98
99	/* set flag whether this packet has to be looped back */
100	loop = skb->pkt_type == PACKET_LOOPBACK;
101
102	skb_tx_timestamp(skb);
103
104	if (!echo) {
105		/* no echo handling available inside this driver */
106		if (loop) {
107			/* only count the packets here, because the
108			 * CAN core already did the echo for us
109			 */
110			stats->rx_packets++;
111			stats->rx_bytes += len;
112		}
113		consume_skb(skb);
114		return NETDEV_TX_OK;
115	}
116
117	/* perform standard echo handling for CAN network interfaces */
118
119	if (loop) {
120		skb = can_create_echo_skb(skb);
121		if (!skb)
122			return NETDEV_TX_OK;
123
124		/* receive with packet counting */
125		vcan_rx(skb, dev);
126	} else {
127		/* no looped packets => no counting */
128		consume_skb(skb);
129	}
130	return NETDEV_TX_OK;
131}
132
133static int vcan_change_mtu(struct net_device *dev, int new_mtu)
134{
135	/* Do not allow changing the MTU while running */
136	if (dev->flags & IFF_UP)
137		return -EBUSY;
138
139	if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU &&
140	    !can_is_canxl_dev_mtu(new_mtu))
141		return -EINVAL;
142
143	dev->mtu = new_mtu;
144	return 0;
145}
146
147static const struct net_device_ops vcan_netdev_ops = {
148	.ndo_start_xmit = vcan_tx,
149	.ndo_change_mtu = vcan_change_mtu,
150};
151
152static const struct ethtool_ops vcan_ethtool_ops = {
153	.get_ts_info = ethtool_op_get_ts_info,
154};
155
156static void vcan_setup(struct net_device *dev)
157{
158	dev->type		= ARPHRD_CAN;
159	dev->mtu		= CANFD_MTU;
160	dev->hard_header_len	= 0;
161	dev->addr_len		= 0;
162	dev->tx_queue_len	= 0;
163	dev->flags		= IFF_NOARP;
164	can_set_ml_priv(dev, netdev_priv(dev));
165
166	/* set flags according to driver capabilities */
167	if (echo)
168		dev->flags |= IFF_ECHO;
169
170	dev->netdev_ops		= &vcan_netdev_ops;
171	dev->ethtool_ops	= &vcan_ethtool_ops;
172	dev->needs_free_netdev	= true;
173}
174
175static struct rtnl_link_ops vcan_link_ops __read_mostly = {
176	.kind = DRV_NAME,
177	.priv_size = sizeof(struct can_ml_priv),
178	.setup = vcan_setup,
179};
180
181static __init int vcan_init_module(void)
182{
183	pr_info("Virtual CAN interface driver\n");
184
185	if (echo)
186		pr_info("enabled echo on driver level.\n");
187
188	return rtnl_link_register(&vcan_link_ops);
189}
190
191static __exit void vcan_cleanup_module(void)
192{
193	rtnl_link_unregister(&vcan_link_ops);
194}
195
196module_init(vcan_init_module);
197module_exit(vcan_cleanup_module);
198