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 #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
  43 static const char* version = "HDLC support module revision 1.22";
  44
  45 #undef DEBUG_LINK
  46
  47 static struct hdlc_proto *first_proto;
  48
  49 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 static 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;
  61
  62         /* First make sure "dev" is an HDLC device */
  63         if (!(dev->priv_flags & IFF_WAN_HDLC)) {
  64                 kfree_skb(skb);
  65                 return NET_RX_SUCCESS;
  66         }
  67
  68         hdlc = dev_to_hdlc(dev);
  69
  70         if (!net_eq(dev_net(dev), &init_net)) {
  71                 kfree_skb(skb);
  72                 return 0;
  73         }
  74
  75         BUG_ON(!hdlc->proto->netif_rx);
  76         return hdlc->proto->netif_rx(skb);
  77 }
  78
  79 netdev_tx_t hdlc_start_xmit(struct sk_buff *skb, struct net_device *dev)
  80 {
  81         hdlc_device *hdlc = dev_to_hdlc(dev);
  82
  83         if (hdlc->proto->xmit)
  84                 return hdlc->proto->xmit(skb, dev);
  85
  86         return hdlc->xmit(skb, dev); /* call hardware driver directly */
  87 }
  88
  89 static inline void hdlc_proto_start(struct net_device *dev)
  90 {
  91         hdlc_device *hdlc = dev_to_hdlc(dev);
  92         if (hdlc->proto->start)
  93                 hdlc->proto->start(dev);
  94 }
  95
  96
  97
  98 static inline void hdlc_proto_stop(struct net_device *dev)
  99 {
 100         hdlc_device *hdlc = dev_to_hdlc(dev);
 101         if (hdlc->proto->stop)
 102                 hdlc->proto->stop(dev);
 103 }
 104
 105
 106
 107 static int hdlc_device_event(struct notifier_block *this, unsigned long event,
 108                              void *ptr)
 109 {
 110         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 111         hdlc_device *hdlc;
 112         unsigned long flags;
 113         int on;
 114
 115         if (!net_eq(dev_net(dev), &init_net))
 116                 return NOTIFY_DONE;
 117
 118         if (!(dev->priv_flags & IFF_WAN_HDLC))
 119                 return NOTIFY_DONE; /* not an HDLC device */
 120
 121         if (event != NETDEV_CHANGE)
 122                 return NOTIFY_DONE; /* Only interested in carrier changes */
 123
 124         on = netif_carrier_ok(dev);
 125
 126 #ifdef DEBUG_LINK
 127         printk(KERN_DEBUG "%s: hdlc_device_event NETDEV_CHANGE, carrier %i\n",
 128                dev->name, on);
 129 #endif
 130
 131         hdlc = dev_to_hdlc(dev);
 132         spin_lock_irqsave(&hdlc->state_lock, flags);
 133
 134         if (hdlc->carrier == on)
 135                 goto carrier_exit; /* no change in DCD line level */
 136
 137         hdlc->carrier = on;
 138
 139         if (!hdlc->open)
 140                 goto carrier_exit;
 141
 142         if (hdlc->carrier) {
 143                 netdev_info(dev, "Carrier detected\n");
 144                 hdlc_proto_start(dev);
 145         } else {
 146                 netdev_info(dev, "Carrier lost\n");
 147                 hdlc_proto_stop(dev);
 148         }
 149
 150 carrier_exit:
 151         spin_unlock_irqrestore(&hdlc->state_lock, flags);
 152         return NOTIFY_DONE;
 153 }
 154
 155
 156
 157 /* Must be called by hardware driver when HDLC device is being opened */
 158 int hdlc_open(struct net_device *dev)
 159 {
 160         hdlc_device *hdlc = dev_to_hdlc(dev);
 161 #ifdef DEBUG_LINK
 162         printk(KERN_DEBUG "%s: hdlc_open() carrier %i open %i\n", dev->name,
 163                hdlc->carrier, hdlc->open);
 164 #endif
 165
 166         if (hdlc->proto == NULL)
 167                 return -ENOSYS; /* no protocol attached */
 168
 169         if (hdlc->proto->open) {
 170                 int result = hdlc->proto->open(dev);
 171                 if (result)
 172                         return result;
 173         }
 174
 175         spin_lock_irq(&hdlc->state_lock);
 176
 177         if (hdlc->carrier) {
 178                 netdev_info(dev, "Carrier detected\n");
 179                 hdlc_proto_start(dev);
 180         } else
 181                 netdev_info(dev, "No carrier\n");
 182
 183         hdlc->open = 1;
 184
 185         spin_unlock_irq(&hdlc->state_lock);
 186         return 0;
 187 }
 188
 189
 190
 191 /* Must be called by hardware driver when HDLC device is being closed */
 192 void hdlc_close(struct net_device *dev)
 193 {
 194         hdlc_device *hdlc = dev_to_hdlc(dev);
 195 #ifdef DEBUG_LINK
 196         printk(KERN_DEBUG "%s: hdlc_close() carrier %i open %i\n", dev->name,
 197                hdlc->carrier, hdlc->open);
 198 #endif
 199
 200         spin_lock_irq(&hdlc->state_lock);
 201
 202         hdlc->open = 0;
 203         if (hdlc->carrier)
 204                 hdlc_proto_stop(dev);
 205
 206         spin_unlock_irq(&hdlc->state_lock);
 207
 208         if (hdlc->proto->close)
 209                 hdlc->proto->close(dev);
 210 }
 211
 212
 213
 214 int hdlc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 215 {
 216         struct hdlc_proto *proto = first_proto;
 217         int result;
 218
 219         if (cmd != SIOCWANDEV)
 220                 return -EINVAL;
 221
 222         if (dev_to_hdlc(dev)->proto) {
 223                 result = dev_to_hdlc(dev)->proto->ioctl(dev, ifr);
 224                 if (result != -EINVAL)
 225                         return result;
 226         }
 227
 228         /* Not handled by currently attached protocol (if any) */
 229
 230         while (proto) {
 231                 if ((result = proto->ioctl(dev, ifr)) != -EINVAL)
 232                         return result;
 233                 proto = proto->next;
 234         }
 235         return -EINVAL;
 236 }
 237
 238 static const struct header_ops hdlc_null_ops;
 239
 240 static void hdlc_setup_dev(struct net_device *dev)
 241 {
 242         /* Re-init all variables changed by HDLC protocol drivers,
 243          * including ether_setup() called from hdlc_raw_eth.c.
 244          */
 245         dev->flags               = IFF_POINTOPOINT | IFF_NOARP;
 246         dev->priv_flags          = IFF_WAN_HDLC;
 247         dev->mtu                 = HDLC_MAX_MTU;
 248         dev->type                = ARPHRD_RAWHDLC;
 249         dev->hard_header_len     = 16;
 250         dev->addr_len            = 0;
 251         dev->header_ops          = &hdlc_null_ops;
 252 }
 253
 254 static void hdlc_setup(struct net_device *dev)
 255 {
 256         hdlc_device *hdlc = dev_to_hdlc(dev);
 257
 258         hdlc_setup_dev(dev);
 259         hdlc->carrier = 1;
 260         hdlc->open = 0;
 261         spin_lock_init(&hdlc->state_lock);
 262 }
 263
 264 struct net_device *alloc_hdlcdev(void *priv)
 265 {
 266         struct net_device *dev;
 267         dev = alloc_netdev(sizeof(struct hdlc_device), "hdlc%d",
 268                            NET_NAME_UNKNOWN, hdlc_setup);
 269         if (dev)
 270                 dev_to_hdlc(dev)->priv = priv;
 271         return dev;
 272 }
 273
 274 void unregister_hdlc_device(struct net_device *dev)
 275 {
 276         rtnl_lock();
 277         unregister_netdevice(dev);
 278         detach_hdlc_protocol(dev);
 279         rtnl_unlock();
 280 }
 281
 282
 283
 284 int attach_hdlc_protocol(struct net_device *dev, struct hdlc_proto *proto,
 285                          size_t size)
 286 {
 287         detach_hdlc_protocol(dev);
 288
 289         if (!try_module_get(proto->module))
 290                 return -ENOSYS;
 291
 292         if (size) {
 293                 dev_to_hdlc(dev)->state = kmalloc(size, GFP_KERNEL);
 294                 if (dev_to_hdlc(dev)->state == NULL) {
 295                         module_put(proto->module);
 296                         return -ENOBUFS;
 297                 }
 298         }
 299         dev_to_hdlc(dev)->proto = proto;
 300         return 0;
 301 }
 302
 303
 304 void detach_hdlc_protocol(struct net_device *dev)
 305 {
 306         hdlc_device *hdlc = dev_to_hdlc(dev);
 307
 308         if (hdlc->proto) {
 309                 if (hdlc->proto->detach)
 310                         hdlc->proto->detach(dev);
 311                 module_put(hdlc->proto->module);
 312                 hdlc->proto = NULL;
 313         }
 314         kfree(hdlc->state);
 315         hdlc->state = NULL;
 316         hdlc_setup_dev(dev);
 317 }
 318
 319
 320 void register_hdlc_protocol(struct hdlc_proto *proto)
 321 {
 322         rtnl_lock();
 323         proto->next = first_proto;
 324         first_proto = proto;
 325         rtnl_unlock();
 326 }
 327
 328
 329 void unregister_hdlc_protocol(struct hdlc_proto *proto)
 330 {
 331         struct hdlc_proto **p;
 332
 333         rtnl_lock();
 334         p = &first_proto;
 335         while (*p != proto) {
 336                 BUG_ON(!*p);
 337                 p = &((*p)->next);
 338         }
 339         *p = proto->next;
 340         rtnl_unlock();
 341 }
 342
 343
 344
 345 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
 346 MODULE_DESCRIPTION("HDLC support module");
 347 MODULE_LICENSE("GPL v2");
 348
 349 EXPORT_SYMBOL(hdlc_change_mtu);
 350 EXPORT_SYMBOL(hdlc_start_xmit);
 351 EXPORT_SYMBOL(hdlc_open);
 352 EXPORT_SYMBOL(hdlc_close);
 353 EXPORT_SYMBOL(hdlc_ioctl);
 354 EXPORT_SYMBOL(alloc_hdlcdev);
 355 EXPORT_SYMBOL(unregister_hdlc_device);
 356 EXPORT_SYMBOL(register_hdlc_protocol);
 357 EXPORT_SYMBOL(unregister_hdlc_protocol);
 358 EXPORT_SYMBOL(attach_hdlc_protocol);
 359 EXPORT_SYMBOL(detach_hdlc_protocol);
 360
 361 static struct packet_type hdlc_packet_type __read_mostly = {
 362         .type = cpu_to_be16(ETH_P_HDLC),
 363         .func = hdlc_rcv,
 364 };
 365
 366
 367 static struct notifier_block hdlc_notifier = {
 368         .notifier_call = hdlc_device_event,
 369 };
 370
 371
 372 static int __init hdlc_module_init(void)
 373 {
 374         int result;
 375
 376         pr_info("%s\n", version);
 377         if ((result = register_netdevice_notifier(&hdlc_notifier)) != 0)
 378                 return result;
 379         dev_add_pack(&hdlc_packet_type);
 380         return 0;
 381 }
 382
 383
 384
 385 static void __exit hdlc_module_exit(void)
 386 {
 387         dev_remove_pack(&hdlc_packet_type);
 388         unregister_netdevice_notifier(&hdlc_notifier);
 389 }
 390
 391
 392 module_init(hdlc_module_init);
 393 module_exit(hdlc_module_exit);