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
43static const char* version = "HDLC support module revision 1.22";
44
45#undef DEBUG_LINK
46
47static struct hdlc_proto *first_proto;
48
49int 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
57static 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
71netdev_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
81static 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
90static 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
99static int hdlc_device_event(struct notifier_block *this, unsigned long event,
100			     void *ptr)
101{
102	struct net_device *dev = netdev_notifier_info_to_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
142carrier_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 */
150int 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 */
184void 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
206int 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
230static const struct header_ops hdlc_null_ops;
231
232static 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
246static 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
256struct net_device *alloc_hdlcdev(void *priv)
257{
258	struct net_device *dev;
259	dev = alloc_netdev(sizeof(struct hdlc_device), "hdlc%d",
260			   NET_NAME_UNKNOWN, hdlc_setup);
261	if (dev)
262		dev_to_hdlc(dev)->priv = priv;
263	return dev;
264}
265
266void unregister_hdlc_device(struct net_device *dev)
267{
268	rtnl_lock();
269	unregister_netdevice(dev);
270	detach_hdlc_protocol(dev);
271	rtnl_unlock();
272}
273
274
275
276int attach_hdlc_protocol(struct net_device *dev, struct hdlc_proto *proto,
277			 size_t size)
278{
279	detach_hdlc_protocol(dev);
280
281	if (!try_module_get(proto->module))
282		return -ENOSYS;
283
284	if (size) {
285		dev_to_hdlc(dev)->state = kmalloc(size, GFP_KERNEL);
286		if (dev_to_hdlc(dev)->state == NULL) {
287			module_put(proto->module);
288			return -ENOBUFS;
289		}
290	}
291	dev_to_hdlc(dev)->proto = proto;
292	return 0;
293}
294
295
296void 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
312void 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
321void 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
337MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
338MODULE_DESCRIPTION("HDLC support module");
339MODULE_LICENSE("GPL v2");
340
341EXPORT_SYMBOL(hdlc_change_mtu);
342EXPORT_SYMBOL(hdlc_start_xmit);
343EXPORT_SYMBOL(hdlc_open);
344EXPORT_SYMBOL(hdlc_close);
345EXPORT_SYMBOL(hdlc_ioctl);
346EXPORT_SYMBOL(alloc_hdlcdev);
347EXPORT_SYMBOL(unregister_hdlc_device);
348EXPORT_SYMBOL(register_hdlc_protocol);
349EXPORT_SYMBOL(unregister_hdlc_protocol);
350EXPORT_SYMBOL(attach_hdlc_protocol);
351EXPORT_SYMBOL(detach_hdlc_protocol);
352
353static struct packet_type hdlc_packet_type __read_mostly = {
354	.type = cpu_to_be16(ETH_P_HDLC),
355	.func = hdlc_rcv,
356};
357
358
359static struct notifier_block hdlc_notifier = {
360	.notifier_call = hdlc_device_event,
361};
362
363
364static 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
377static void __exit hdlc_module_exit(void)
378{
379	dev_remove_pack(&hdlc_packet_type);
380	unregister_netdevice_notifier(&hdlc_notifier);
381}
382
383
384module_init(hdlc_module_init);
385module_exit(hdlc_module_exit);
386