drivers/net/wan/hdlc.c

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