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