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 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 static int hdlc_rcv(struct sk_buff *skb, struct net_device *dev,
  56                     struct packet_type *p, struct net_device *orig_dev)
  57 {
  58         struct hdlc_device *hdlc = dev_to_hdlc(dev);
  59
  60         if (!net_eq(dev_net(dev), &init_net)) {
  61                 kfree_skb(skb);
  62                 return 0;
  63         }
  64
  65         BUG_ON(!hdlc->proto->netif_rx);
  66         return hdlc->proto->netif_rx(skb);
  67 }
  68
  69 netdev_tx_t hdlc_start_xmit(struct sk_buff *skb, struct net_device *dev)
  70 {
  71         hdlc_device *hdlc = dev_to_hdlc(dev);
  72
  73         if (hdlc->proto->xmit)
  74                 return hdlc->proto->xmit(skb, dev);
  75
  76         return hdlc->xmit(skb, dev); /* call hardware driver directly */
  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                 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                 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 (!net_eq(dev_net(dev), &init_net))
 106                 return NOTIFY_DONE;
 107
 108         if (!(dev->priv_flags & IFF_WAN_HDLC))
 109                 return NOTIFY_DONE; /* not an HDLC device */
 110
 111         if (event != NETDEV_CHANGE)
 112                 return NOTIFY_DONE; /* Only interested in carrier changes */
 113
 114         on = netif_carrier_ok(dev);
 115
 116 #ifdef DEBUG_LINK
 117         printk(KERN_DEBUG "%s: hdlc_device_event NETDEV_CHANGE, carrier %i\n",
 118                dev->name, on);
 119 #endif
 120
 121         hdlc = dev_to_hdlc(dev);
 122         spin_lock_irqsave(&hdlc->state_lock, flags);
 123
 124         if (hdlc->carrier == on)
 125                 goto carrier_exit; /* no change in DCD line level */
 126
 127         hdlc->carrier = on;
 128
 129         if (!hdlc->open)
 130                 goto carrier_exit;
 131
 132         if (hdlc->carrier) {
 133                 printk(KERN_INFO "%s: Carrier detected\n", dev->name);
 134                 hdlc_proto_start(dev);
 135         } else {
 136                 printk(KERN_INFO "%s: Carrier lost\n", dev->name);
 137                 hdlc_proto_stop(dev);
 138         }
 139
 140 carrier_exit:
 141         spin_unlock_irqrestore(&hdlc->state_lock, flags);
 142         return NOTIFY_DONE;
 143 }
 144
 145
 146
 147 /* Must be called by hardware driver when HDLC device is being opened */
 148 int hdlc_open(struct net_device *dev)
 149 {
 150         hdlc_device *hdlc = dev_to_hdlc(dev);
 151 #ifdef DEBUG_LINK
 152         printk(KERN_DEBUG "%s: hdlc_open() carrier %i open %i\n", dev->name,
 153                hdlc->carrier, hdlc->open);
 154 #endif
 155
 156         if (hdlc->proto == NULL)
 157                 return -ENOSYS; /* no protocol attached */
 158
 159         if (hdlc->proto->open) {
 160                 int result = hdlc->proto->open(dev);
 161                 if (result)
 162                         return result;
 163         }
 164
 165         spin_lock_irq(&hdlc->state_lock);
 166
 167         if (hdlc->carrier) {
 168                 printk(KERN_INFO "%s: Carrier detected\n", dev->name);
 169                 hdlc_proto_start(dev);
 170         } else
 171                 printk(KERN_INFO "%s: No carrier\n", dev->name);
 172
 173         hdlc->open = 1;
 174
 175         spin_unlock_irq(&hdlc->state_lock);
 176         return 0;
 177 }
 178
 179
 180
 181 /* Must be called by hardware driver when HDLC device is being closed */
 182 void hdlc_close(struct net_device *dev)
 183 {
 184         hdlc_device *hdlc = dev_to_hdlc(dev);
 185 #ifdef DEBUG_LINK
 186         printk(KERN_DEBUG "%s: hdlc_close() carrier %i open %i\n", dev->name,
 187                hdlc->carrier, hdlc->open);
 188 #endif
 189
 190         spin_lock_irq(&hdlc->state_lock);
 191
 192         hdlc->open = 0;
 193         if (hdlc->carrier)
 194                 hdlc_proto_stop(dev);
 195
 196         spin_unlock_irq(&hdlc->state_lock);
 197
 198         if (hdlc->proto->close)
 199                 hdlc->proto->close(dev);
 200 }
 201
 202
 203
 204 int hdlc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 205 {
 206         struct hdlc_proto *proto = first_proto;
 207         int result;
 208
 209         if (cmd != SIOCWANDEV)
 210                 return -EINVAL;
 211
 212         if (dev_to_hdlc(dev)->proto) {
 213                 result = dev_to_hdlc(dev)->proto->ioctl(dev, ifr);
 214                 if (result != -EINVAL)
 215                         return result;
 216         }
 217
 218         /* Not handled by currently attached protocol (if any) */
 219
 220         while (proto) {
 221                 if ((result = proto->ioctl(dev, ifr)) != -EINVAL)
 222                         return result;
 223                 proto = proto->next;
 224         }
 225         return -EINVAL;
 226 }
 227
 228 static const struct header_ops hdlc_null_ops;
 229
 230 static void hdlc_setup_dev(struct net_device *dev)
 231 {
 232         /* Re-init all variables changed by HDLC protocol drivers,
 233          * including ether_setup() called from hdlc_raw_eth.c.
 234          */
 235         dev->flags               = IFF_POINTOPOINT | IFF_NOARP;
 236         dev->priv_flags          = IFF_WAN_HDLC;
 237         dev->mtu                 = HDLC_MAX_MTU;
 238         dev->type                = ARPHRD_RAWHDLC;
 239         dev->hard_header_len     = 16;
 240         dev->addr_len            = 0;
 241         dev->header_ops          = &hdlc_null_ops;
 242 }
 243
 244 static void hdlc_setup(struct net_device *dev)
 245 {
 246         hdlc_device *hdlc = dev_to_hdlc(dev);
 247
 248         hdlc_setup_dev(dev);
 249         hdlc->carrier = 1;
 250         hdlc->open = 0;
 251         spin_lock_init(&hdlc->state_lock);
 252 }
 253
 254 struct net_device *alloc_hdlcdev(void *priv)
 255 {
 256         struct net_device *dev;
 257         dev = alloc_netdev(sizeof(struct hdlc_device), "hdlc%d", hdlc_setup);
 258         if (dev)
 259                 dev_to_hdlc(dev)->priv = priv;
 260         return dev;
 261 }
 262
 263 void unregister_hdlc_device(struct net_device *dev)
 264 {
 265         rtnl_lock();
 266         unregister_netdevice(dev);
 267         detach_hdlc_protocol(dev);
 268         rtnl_unlock();
 269 }
 270
 271
 272
 273 int attach_hdlc_protocol(struct net_device *dev, struct hdlc_proto *proto,
 274                          size_t size)
 275 {
 276         detach_hdlc_protocol(dev);
 277
 278         if (!try_module_get(proto->module))
 279                 return -ENOSYS;
 280
 281         if (size)
 282                 if ((dev_to_hdlc(dev)->state = kmalloc(size,
 283                                                        GFP_KERNEL)) == NULL) {
 284                         printk(KERN_WARNING "Memory squeeze on"
 285                                " hdlc_proto_attach()\n");
 286                         module_put(proto->module);
 287                         return -ENOBUFS;
 288                 }
 289         dev_to_hdlc(dev)->proto = proto;
 290         return 0;
 291 }
 292
 293
 294 void detach_hdlc_protocol(struct net_device *dev)
 295 {
 296         hdlc_device *hdlc = dev_to_hdlc(dev);
 297
 298         if (hdlc->proto) {
 299                 if (hdlc->proto->detach)
 300                         hdlc->proto->detach(dev);
 301                 module_put(hdlc->proto->module);
 302                 hdlc->proto = NULL;
 303         }
 304         kfree(hdlc->state);
 305         hdlc->state = NULL;
 306         hdlc_setup_dev(dev);
 307 }
 308
 309
 310 void register_hdlc_protocol(struct hdlc_proto *proto)
 311 {
 312         rtnl_lock();
 313         proto->next = first_proto;
 314         first_proto = proto;
 315         rtnl_unlock();
 316 }
 317
 318
 319 void unregister_hdlc_protocol(struct hdlc_proto *proto)
 320 {
 321         struct hdlc_proto **p;
 322
 323         rtnl_lock();
 324         p = &first_proto;
 325         while (*p != proto) {
 326                 BUG_ON(!*p);
 327                 p = &((*p)->next);
 328         }
 329         *p = proto->next;
 330         rtnl_unlock();
 331 }
 332
 333
 334
 335 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
 336 MODULE_DESCRIPTION("HDLC support module");
 337 MODULE_LICENSE("GPL v2");
 338
 339 EXPORT_SYMBOL(hdlc_change_mtu);
 340 EXPORT_SYMBOL(hdlc_start_xmit);
 341 EXPORT_SYMBOL(hdlc_open);
 342 EXPORT_SYMBOL(hdlc_close);
 343 EXPORT_SYMBOL(hdlc_ioctl);
 344 EXPORT_SYMBOL(alloc_hdlcdev);
 345 EXPORT_SYMBOL(unregister_hdlc_device);
 346 EXPORT_SYMBOL(register_hdlc_protocol);
 347 EXPORT_SYMBOL(unregister_hdlc_protocol);
 348 EXPORT_SYMBOL(attach_hdlc_protocol);
 349 EXPORT_SYMBOL(detach_hdlc_protocol);
 350
 351 static struct packet_type hdlc_packet_type __read_mostly = {
 352         .type = cpu_to_be16(ETH_P_HDLC),
 353         .func = hdlc_rcv,
 354 };
 355
 356
 357 static struct notifier_block hdlc_notifier = {
 358         .notifier_call = hdlc_device_event,
 359 };
 360
 361
 362 static int __init hdlc_module_init(void)
 363 {
 364         int result;
 365
 366         printk(KERN_INFO "%s\n", version);
 367         if ((result = register_netdevice_notifier(&hdlc_notifier)) != 0)
 368                 return result;
 369         dev_add_pack(&hdlc_packet_type);
 370         return 0;
 371 }
 372
 373
 374
 375 static void __exit hdlc_module_exit(void)
 376 {
 377         dev_remove_pack(&hdlc_packet_type);
 378         unregister_netdevice_notifier(&hdlc_notifier);
 379 }
 380
 381
 382 module_init(hdlc_module_init);
 383 module_exit(hdlc_module_exit);