drivers/net/wan/hdlc.c

   1 /*
   2  * Generic HDLC support routines for Linux
   3  *
   4  * Copyright (C) 1999 - 2006 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
  40
  41 static const char* version = "HDLC support module revision 1.20";
  42
  43 #undef DEBUG_LINK
  44
  45 static struct hdlc_proto *first_proto = NULL;
  46
  47
  48 static int hdlc_change_mtu(struct net_device *dev, int new_mtu)
  49 {
  50         if ((new_mtu < 68) || (new_mtu > HDLC_MAX_MTU))
  51                 return -EINVAL;
  52         dev->mtu = new_mtu;
  53         return 0;
  54 }
  55
  56
  57
  58 static struct net_device_stats *hdlc_get_stats(struct net_device *dev)
  59 {
  60         return hdlc_stats(dev);
  61 }
  62
  63
  64
  65 static int hdlc_rcv(struct sk_buff *skb, struct net_device *dev,
  66                     struct packet_type *p, struct net_device *orig_dev)
  67 {
  68         struct hdlc_device_desc *desc = dev_to_desc(dev);
  69         if (desc->netif_rx)
  70                 return desc->netif_rx(skb);
  71
  72         desc->stats.rx_dropped++; /* Shouldn't happen */
  73         dev_kfree_skb(skb);
  74         return NET_RX_DROP;
  75 }
  76
  77
  78
  79 static inline void hdlc_proto_start(struct net_device *dev)
  80 {
  81         hdlc_device *hdlc = dev_to_hdlc(dev);
  82         if (hdlc->proto->start)
  83                 return hdlc->proto->start(dev);
  84 }
  85
  86
  87
  88 static inline void hdlc_proto_stop(struct net_device *dev)
  89 {
  90         hdlc_device *hdlc = dev_to_hdlc(dev);
  91         if (hdlc->proto->stop)
  92                 return hdlc->proto->stop(dev);
  93 }
  94
  95
  96
  97 static int hdlc_device_event(struct notifier_block *this, unsigned long event,
  98                              void *ptr)
  99 {
 100         struct net_device *dev = ptr;
 101         hdlc_device *hdlc;
 102         unsigned long flags;
 103         int on;
 104
 105         if (dev->get_stats != hdlc_get_stats)
 106                 return NOTIFY_DONE; /* not an HDLC device */
 107
 108         if (event != NETDEV_CHANGE)
 109                 return NOTIFY_DONE; /* Only interrested in carrier changes */
 110
 111         on = netif_carrier_ok(dev);
 112
 113 #ifdef DEBUG_LINK
 114         printk(KERN_DEBUG "%s: hdlc_device_event NETDEV_CHANGE, carrier %i\n",
 115                dev->name, on);
 116 #endif
 117
 118         hdlc = dev_to_hdlc(dev);
 119         spin_lock_irqsave(&hdlc->state_lock, flags);
 120
 121         if (hdlc->carrier == on)
 122                 goto carrier_exit; /* no change in DCD line level */
 123
 124         hdlc->carrier = on;
 125
 126         if (!hdlc->open)
 127                 goto carrier_exit;
 128
 129         if (hdlc->carrier) {
 130                 printk(KERN_INFO "%s: Carrier detected\n", dev->name);
 131                 hdlc_proto_start(dev);
 132         } else {
 133                 printk(KERN_INFO "%s: Carrier lost\n", dev->name);
 134                 hdlc_proto_stop(dev);
 135         }
 136
 137 carrier_exit:
 138         spin_unlock_irqrestore(&hdlc->state_lock, flags);
 139         return NOTIFY_DONE;
 140 }
 141
 142
 143
 144 /* Must be called by hardware driver when HDLC device is being opened */
 145 int hdlc_open(struct net_device *dev)
 146 {
 147         hdlc_device *hdlc = dev_to_hdlc(dev);
 148 #ifdef DEBUG_LINK
 149         printk(KERN_DEBUG "%s: hdlc_open() carrier %i open %i\n", dev->name,
 150                hdlc->carrier, hdlc->open);
 151 #endif
 152
 153         if (hdlc->proto == NULL)
 154                 return -ENOSYS; /* no protocol attached */
 155
 156         if (hdlc->proto->open) {
 157                 int result = hdlc->proto->open(dev);
 158                 if (result)
 159                         return result;
 160         }
 161
 162         spin_lock_irq(&hdlc->state_lock);
 163
 164         if (hdlc->carrier) {
 165                 printk(KERN_INFO "%s: Carrier detected\n", dev->name);
 166                 hdlc_proto_start(dev);
 167         } else
 168                 printk(KERN_INFO "%s: No carrier\n", dev->name);
 169
 170         hdlc->open = 1;
 171
 172         spin_unlock_irq(&hdlc->state_lock);
 173         return 0;
 174 }
 175
 176
 177
 178 /* Must be called by hardware driver when HDLC device is being closed */
 179 void hdlc_close(struct net_device *dev)
 180 {
 181         hdlc_device *hdlc = dev_to_hdlc(dev);
 182 #ifdef DEBUG_LINK
 183         printk(KERN_DEBUG "%s: hdlc_close() carrier %i open %i\n", dev->name,
 184                hdlc->carrier, hdlc->open);
 185 #endif
 186
 187         spin_lock_irq(&hdlc->state_lock);
 188
 189         hdlc->open = 0;
 190         if (hdlc->carrier)
 191                 hdlc_proto_stop(dev);
 192
 193         spin_unlock_irq(&hdlc->state_lock);
 194
 195         if (hdlc->proto->close)
 196                 hdlc->proto->close(dev);
 197 }
 198
 199
 200
 201 int hdlc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 202 {
 203         struct hdlc_proto *proto = first_proto;
 204         int result;
 205
 206         if (cmd != SIOCWANDEV)
 207                 return -EINVAL;
 208
 209         if (dev_to_hdlc(dev)->proto) {
 210                 result = dev_to_hdlc(dev)->proto->ioctl(dev, ifr);
 211                 if (result != -EINVAL)
 212                         return result;
 213         }
 214
 215         /* Not handled by currently attached protocol (if any) */
 216
 217         while (proto) {
 218                 if ((result = proto->ioctl(dev, ifr)) != -EINVAL)
 219                         return result;
 220                 proto = proto->next;
 221         }
 222         return -EINVAL;
 223 }
 224
 225 void hdlc_setup(struct net_device *dev)
 226 {
 227         hdlc_device *hdlc = dev_to_hdlc(dev);
 228
 229         dev->get_stats = hdlc_get_stats;
 230         dev->change_mtu = hdlc_change_mtu;
 231         dev->mtu = HDLC_MAX_MTU;
 232
 233         dev->type = ARPHRD_RAWHDLC;
 234         dev->hard_header_len = 16;
 235
 236         dev->flags = IFF_POINTOPOINT | IFF_NOARP;
 237
 238         hdlc->carrier = 1;
 239         hdlc->open = 0;
 240         spin_lock_init(&hdlc->state_lock);
 241 }
 242
 243 struct net_device *alloc_hdlcdev(void *priv)
 244 {
 245         struct net_device *dev;
 246         dev = alloc_netdev(sizeof(struct hdlc_device_desc) +
 247                            sizeof(hdlc_device), "hdlc%d", hdlc_setup);
 248         if (dev)
 249                 dev_to_hdlc(dev)->priv = priv;
 250         return dev;
 251 }
 252
 253 void unregister_hdlc_device(struct net_device *dev)
 254 {
 255         rtnl_lock();
 256         unregister_netdevice(dev);
 257         detach_hdlc_protocol(dev);
 258         rtnl_unlock();
 259 }
 260
 261
 262
 263 int attach_hdlc_protocol(struct net_device *dev, struct hdlc_proto *proto,
 264                          int (*rx)(struct sk_buff *skb), size_t size)
 265 {
 266         detach_hdlc_protocol(dev);
 267
 268         if (!try_module_get(proto->module))
 269                 return -ENOSYS;
 270
 271         if (size)
 272                 if ((dev_to_hdlc(dev)->state = kmalloc(size,
 273                                                        GFP_KERNEL)) == NULL) {
 274                         printk(KERN_WARNING "Memory squeeze on"
 275                                " hdlc_proto_attach()\n");
 276                         module_put(proto->module);
 277                         return -ENOBUFS;
 278                 }
 279         dev_to_hdlc(dev)->proto = proto;
 280         dev_to_desc(dev)->netif_rx = rx;
 281         return 0;
 282 }
 283
 284
 285 void detach_hdlc_protocol(struct net_device *dev)
 286 {
 287         hdlc_device *hdlc = dev_to_hdlc(dev);
 288
 289         if (hdlc->proto) {
 290                 if (hdlc->proto->detach)
 291                         hdlc->proto->detach(dev);
 292                 module_put(hdlc->proto->module);
 293                 hdlc->proto = NULL;
 294         }
 295         kfree(hdlc->state);
 296         hdlc->state = NULL;
 297 }
 298
 299
 300 void register_hdlc_protocol(struct hdlc_proto *proto)
 301 {
 302         proto->next = first_proto;
 303         first_proto = proto;
 304 }
 305
 306
 307 void unregister_hdlc_protocol(struct hdlc_proto *proto)
 308 {
 309         struct hdlc_proto **p = &first_proto;
 310         while (*p) {
 311                 if (*p == proto) {
 312                         *p = proto->next;
 313                         return;
 314                 }
 315                 p = &((*p)->next);
 316         }
 317 }
 318
 319
 320
 321 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
 322 MODULE_DESCRIPTION("HDLC support module");
 323 MODULE_LICENSE("GPL v2");
 324
 325 EXPORT_SYMBOL(hdlc_open);
 326 EXPORT_SYMBOL(hdlc_close);
 327 EXPORT_SYMBOL(hdlc_ioctl);
 328 EXPORT_SYMBOL(hdlc_setup);
 329 EXPORT_SYMBOL(alloc_hdlcdev);
 330 EXPORT_SYMBOL(unregister_hdlc_device);
 331 EXPORT_SYMBOL(register_hdlc_protocol);
 332 EXPORT_SYMBOL(unregister_hdlc_protocol);
 333 EXPORT_SYMBOL(attach_hdlc_protocol);
 334 EXPORT_SYMBOL(detach_hdlc_protocol);
 335
 336 static struct packet_type hdlc_packet_type = {
 337         .type = __constant_htons(ETH_P_HDLC),
 338         .func = hdlc_rcv,
 339 };
 340
 341
 342 static struct notifier_block hdlc_notifier = {
 343         .notifier_call = hdlc_device_event,
 344 };
 345
 346
 347 static int __init hdlc_module_init(void)
 348 {
 349         int result;
 350
 351         printk(KERN_INFO "%s\n", version);
 352         if ((result = register_netdevice_notifier(&hdlc_notifier)) != 0)
 353                 return result;
 354         dev_add_pack(&hdlc_packet_type);
 355         return 0;
 356 }
 357
 358
 359
 360 static void __exit hdlc_module_exit(void)
 361 {
 362         dev_remove_pack(&hdlc_packet_type);
 363         unregister_netdevice_notifier(&hdlc_notifier);
 364 }
 365
 366
 367 module_init(hdlc_module_init);
 368 module_exit(hdlc_module_exit);