1 /*
2 * Generic HDLC support routines for Linux
3 *
4 * Copyright (C) 1999 - 2008 Krzysztof Halasa <khc@pm.waw.pl>
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of version 2 of the GNU General Public License
8 * as published by the Free Software Foundation.
9 *
10 * Currently supported:
11 * * raw IP-in-HDLC
12 * * Cisco HDLC
13 * * Frame Relay with ANSI or CCITT LMI (both user and network side)
14 * * PPP
15 * * X.25
16 *
17 * Use sethdlc utility to set line parameters, protocol and PVCs
18 *
19 * How does it work:
20 * - proto->open(), close(), start(), stop() calls are serialized.
21 * The order is: open, [ start, stop ... ] close ...
22 * - proto->start() and stop() are called with spin_lock_irq held.
23 */
24
25 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
26
27 #include <linux/errno.h>
28 #include <linux/hdlc.h>
29 #include <linux/if_arp.h>
30 #include <linux/inetdevice.h>
31 #include <linux/init.h>
32 #include <linux/kernel.h>
33 #include <linux/module.h>
34 #include <linux/notifier.h>
35 #include <linux/pkt_sched.h>
36 #include <linux/poll.h>
37 #include <linux/rtnetlink.h>
38 #include <linux/skbuff.h>
39 #include <linux/slab.h>
40 #include <net/net_namespace.h>
41
42
43 static const char* version = "HDLC support module revision 1.22";
44
45 #undef DEBUG_LINK
46
47 static struct hdlc_proto *first_proto;
48
hdlc_change_mtu(struct net_device * dev,int new_mtu)49 int hdlc_change_mtu(struct net_device *dev, int new_mtu)
50 {
51 if ((new_mtu < 68) || (new_mtu > HDLC_MAX_MTU))
52 return -EINVAL;
53 dev->mtu = new_mtu;
54 return 0;
55 }
56
hdlc_rcv(struct sk_buff * skb,struct net_device * dev,struct packet_type * p,struct net_device * orig_dev)57 static int hdlc_rcv(struct sk_buff *skb, struct net_device *dev,
58 struct packet_type *p, struct net_device *orig_dev)
59 {
60 struct hdlc_device *hdlc = dev_to_hdlc(dev);
61
62 if (!net_eq(dev_net(dev), &init_net)) {
63 kfree_skb(skb);
64 return 0;
65 }
66
67 BUG_ON(!hdlc->proto->netif_rx);
68 return hdlc->proto->netif_rx(skb);
69 }
70
hdlc_start_xmit(struct sk_buff * skb,struct net_device * dev)71 netdev_tx_t hdlc_start_xmit(struct sk_buff *skb, struct net_device *dev)
72 {
73 hdlc_device *hdlc = dev_to_hdlc(dev);
74
75 if (hdlc->proto->xmit)
76 return hdlc->proto->xmit(skb, dev);
77
78 return hdlc->xmit(skb, dev); /* call hardware driver directly */
79 }
80
hdlc_proto_start(struct net_device * dev)81 static inline void hdlc_proto_start(struct net_device *dev)
82 {
83 hdlc_device *hdlc = dev_to_hdlc(dev);
84 if (hdlc->proto->start)
85 hdlc->proto->start(dev);
86 }
87
88
89
hdlc_proto_stop(struct net_device * dev)90 static inline void hdlc_proto_stop(struct net_device *dev)
91 {
92 hdlc_device *hdlc = dev_to_hdlc(dev);
93 if (hdlc->proto->stop)
94 hdlc->proto->stop(dev);
95 }
96
97
98
hdlc_device_event(struct notifier_block * this,unsigned long event,void * ptr)99 static int hdlc_device_event(struct notifier_block *this, unsigned long event,
100 void *ptr)
101 {
102 struct net_device *dev = ptr;
103 hdlc_device *hdlc;
104 unsigned long flags;
105 int on;
106
107 if (!net_eq(dev_net(dev), &init_net))
108 return NOTIFY_DONE;
109
110 if (!(dev->priv_flags & IFF_WAN_HDLC))
111 return NOTIFY_DONE; /* not an HDLC device */
112
113 if (event != NETDEV_CHANGE)
114 return NOTIFY_DONE; /* Only interested in carrier changes */
115
116 on = netif_carrier_ok(dev);
117
118 #ifdef DEBUG_LINK
119 printk(KERN_DEBUG "%s: hdlc_device_event NETDEV_CHANGE, carrier %i\n",
120 dev->name, on);
121 #endif
122
123 hdlc = dev_to_hdlc(dev);
124 spin_lock_irqsave(&hdlc->state_lock, flags);
125
126 if (hdlc->carrier == on)
127 goto carrier_exit; /* no change in DCD line level */
128
129 hdlc->carrier = on;
130
131 if (!hdlc->open)
132 goto carrier_exit;
133
134 if (hdlc->carrier) {
135 netdev_info(dev, "Carrier detected\n");
136 hdlc_proto_start(dev);
137 } else {
138 netdev_info(dev, "Carrier lost\n");
139 hdlc_proto_stop(dev);
140 }
141
142 carrier_exit:
143 spin_unlock_irqrestore(&hdlc->state_lock, flags);
144 return NOTIFY_DONE;
145 }
146
147
148
149 /* Must be called by hardware driver when HDLC device is being opened */
hdlc_open(struct net_device * dev)150 int hdlc_open(struct net_device *dev)
151 {
152 hdlc_device *hdlc = dev_to_hdlc(dev);
153 #ifdef DEBUG_LINK
154 printk(KERN_DEBUG "%s: hdlc_open() carrier %i open %i\n", dev->name,
155 hdlc->carrier, hdlc->open);
156 #endif
157
158 if (hdlc->proto == NULL)
159 return -ENOSYS; /* no protocol attached */
160
161 if (hdlc->proto->open) {
162 int result = hdlc->proto->open(dev);
163 if (result)
164 return result;
165 }
166
167 spin_lock_irq(&hdlc->state_lock);
168
169 if (hdlc->carrier) {
170 netdev_info(dev, "Carrier detected\n");
171 hdlc_proto_start(dev);
172 } else
173 netdev_info(dev, "No carrier\n");
174
175 hdlc->open = 1;
176
177 spin_unlock_irq(&hdlc->state_lock);
178 return 0;
179 }
180
181
182
183 /* Must be called by hardware driver when HDLC device is being closed */
hdlc_close(struct net_device * dev)184 void hdlc_close(struct net_device *dev)
185 {
186 hdlc_device *hdlc = dev_to_hdlc(dev);
187 #ifdef DEBUG_LINK
188 printk(KERN_DEBUG "%s: hdlc_close() carrier %i open %i\n", dev->name,
189 hdlc->carrier, hdlc->open);
190 #endif
191
192 spin_lock_irq(&hdlc->state_lock);
193
194 hdlc->open = 0;
195 if (hdlc->carrier)
196 hdlc_proto_stop(dev);
197
198 spin_unlock_irq(&hdlc->state_lock);
199
200 if (hdlc->proto->close)
201 hdlc->proto->close(dev);
202 }
203
204
205
hdlc_ioctl(struct net_device * dev,struct ifreq * ifr,int cmd)206 int hdlc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
207 {
208 struct hdlc_proto *proto = first_proto;
209 int result;
210
211 if (cmd != SIOCWANDEV)
212 return -EINVAL;
213
214 if (dev_to_hdlc(dev)->proto) {
215 result = dev_to_hdlc(dev)->proto->ioctl(dev, ifr);
216 if (result != -EINVAL)
217 return result;
218 }
219
220 /* Not handled by currently attached protocol (if any) */
221
222 while (proto) {
223 if ((result = proto->ioctl(dev, ifr)) != -EINVAL)
224 return result;
225 proto = proto->next;
226 }
227 return -EINVAL;
228 }
229
230 static const struct header_ops hdlc_null_ops;
231
hdlc_setup_dev(struct net_device * dev)232 static void hdlc_setup_dev(struct net_device *dev)
233 {
234 /* Re-init all variables changed by HDLC protocol drivers,
235 * including ether_setup() called from hdlc_raw_eth.c.
236 */
237 dev->flags = IFF_POINTOPOINT | IFF_NOARP;
238 dev->priv_flags = IFF_WAN_HDLC;
239 dev->mtu = HDLC_MAX_MTU;
240 dev->type = ARPHRD_RAWHDLC;
241 dev->hard_header_len = 16;
242 dev->addr_len = 0;
243 dev->header_ops = &hdlc_null_ops;
244 }
245
hdlc_setup(struct net_device * dev)246 static void hdlc_setup(struct net_device *dev)
247 {
248 hdlc_device *hdlc = dev_to_hdlc(dev);
249
250 hdlc_setup_dev(dev);
251 hdlc->carrier = 1;
252 hdlc->open = 0;
253 spin_lock_init(&hdlc->state_lock);
254 }
255
alloc_hdlcdev(void * priv)256 struct net_device *alloc_hdlcdev(void *priv)
257 {
258 struct net_device *dev;
259 dev = alloc_netdev(sizeof(struct hdlc_device), "hdlc%d", hdlc_setup);
260 if (dev)
261 dev_to_hdlc(dev)->priv = priv;
262 return dev;
263 }
264
unregister_hdlc_device(struct net_device * dev)265 void unregister_hdlc_device(struct net_device *dev)
266 {
267 rtnl_lock();
268 unregister_netdevice(dev);
269 detach_hdlc_protocol(dev);
270 rtnl_unlock();
271 }
272
273
274
attach_hdlc_protocol(struct net_device * dev,struct hdlc_proto * proto,size_t size)275 int attach_hdlc_protocol(struct net_device *dev, struct hdlc_proto *proto,
276 size_t size)
277 {
278 detach_hdlc_protocol(dev);
279
280 if (!try_module_get(proto->module))
281 return -ENOSYS;
282
283 if (size)
284 if ((dev_to_hdlc(dev)->state = kmalloc(size,
285 GFP_KERNEL)) == NULL) {
286 netdev_warn(dev,
287 "Memory squeeze on hdlc_proto_attach()\n");
288 module_put(proto->module);
289 return -ENOBUFS;
290 }
291 dev_to_hdlc(dev)->proto = proto;
292 return 0;
293 }
294
295
detach_hdlc_protocol(struct net_device * dev)296 void detach_hdlc_protocol(struct net_device *dev)
297 {
298 hdlc_device *hdlc = dev_to_hdlc(dev);
299
300 if (hdlc->proto) {
301 if (hdlc->proto->detach)
302 hdlc->proto->detach(dev);
303 module_put(hdlc->proto->module);
304 hdlc->proto = NULL;
305 }
306 kfree(hdlc->state);
307 hdlc->state = NULL;
308 hdlc_setup_dev(dev);
309 }
310
311
register_hdlc_protocol(struct hdlc_proto * proto)312 void register_hdlc_protocol(struct hdlc_proto *proto)
313 {
314 rtnl_lock();
315 proto->next = first_proto;
316 first_proto = proto;
317 rtnl_unlock();
318 }
319
320
unregister_hdlc_protocol(struct hdlc_proto * proto)321 void unregister_hdlc_protocol(struct hdlc_proto *proto)
322 {
323 struct hdlc_proto **p;
324
325 rtnl_lock();
326 p = &first_proto;
327 while (*p != proto) {
328 BUG_ON(!*p);
329 p = &((*p)->next);
330 }
331 *p = proto->next;
332 rtnl_unlock();
333 }
334
335
336
337 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
338 MODULE_DESCRIPTION("HDLC support module");
339 MODULE_LICENSE("GPL v2");
340
341 EXPORT_SYMBOL(hdlc_change_mtu);
342 EXPORT_SYMBOL(hdlc_start_xmit);
343 EXPORT_SYMBOL(hdlc_open);
344 EXPORT_SYMBOL(hdlc_close);
345 EXPORT_SYMBOL(hdlc_ioctl);
346 EXPORT_SYMBOL(alloc_hdlcdev);
347 EXPORT_SYMBOL(unregister_hdlc_device);
348 EXPORT_SYMBOL(register_hdlc_protocol);
349 EXPORT_SYMBOL(unregister_hdlc_protocol);
350 EXPORT_SYMBOL(attach_hdlc_protocol);
351 EXPORT_SYMBOL(detach_hdlc_protocol);
352
353 static struct packet_type hdlc_packet_type __read_mostly = {
354 .type = cpu_to_be16(ETH_P_HDLC),
355 .func = hdlc_rcv,
356 };
357
358
359 static struct notifier_block hdlc_notifier = {
360 .notifier_call = hdlc_device_event,
361 };
362
363
hdlc_module_init(void)364 static int __init hdlc_module_init(void)
365 {
366 int result;
367
368 pr_info("%s\n", version);
369 if ((result = register_netdevice_notifier(&hdlc_notifier)) != 0)
370 return result;
371 dev_add_pack(&hdlc_packet_type);
372 return 0;
373 }
374
375
376
hdlc_module_exit(void)377 static void __exit hdlc_module_exit(void)
378 {
379 dev_remove_pack(&hdlc_packet_type);
380 unregister_netdevice_notifier(&hdlc_notifier);
381 }
382
383
384 module_init(hdlc_module_init);
385 module_exit(hdlc_module_exit);
386