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 static int hdlc_rcv(struct sk_buff *skb, struct net_device *dev,
  50                     struct packet_type *p, struct net_device *orig_dev)
  51 {
  52         struct hdlc_device *hdlc;
  53
  54         /* First make sure "dev" is an HDLC device */
  55         if (!(dev->priv_flags & IFF_WAN_HDLC)) {
  56                 kfree_skb(skb);
  57                 return NET_RX_SUCCESS;
  58         }
  59
  60         hdlc = dev_to_hdlc(dev);
  61
  62         if (!net_eq(dev_net(dev), &init_net)) {
  63                 kfree_skb(skb);
  64                 return 0;
  65         }
  66
  67         BUG_ON(!hdlc->proto->netif_rx);
  68         return hdlc->proto->netif_rx(skb);
  69 }
  70
  71 netdev_tx_t hdlc_start_xmit(struct sk_buff *skb, struct net_device *dev)
  72 {
  73         hdlc_device *hdlc = dev_to_hdlc(dev);
  74
  75         if (hdlc->proto->xmit)
  76                 return hdlc->proto->xmit(skb, dev);
  77
  78         return hdlc->xmit(skb, dev); /* call hardware driver directly */
  79 }
  80
  81 static inline void hdlc_proto_start(struct net_device *dev)
  82 {
  83         hdlc_device *hdlc = dev_to_hdlc(dev);
  84         if (hdlc->proto->start)
  85                 hdlc->proto->start(dev);
  86 }
  87
  88
  89
  90 static inline void hdlc_proto_stop(struct net_device *dev)
  91 {
  92         hdlc_device *hdlc = dev_to_hdlc(dev);
  93         if (hdlc->proto->stop)
  94                 hdlc->proto->stop(dev);
  95 }
  96
  97
  98
  99 static int hdlc_device_event(struct notifier_block *this, unsigned long event,
 100                              void *ptr)
 101 {
 102         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 103         hdlc_device *hdlc;
 104         unsigned long flags;
 105         int on;
 106
 107         if (!net_eq(dev_net(dev), &init_net))
 108                 return NOTIFY_DONE;
 109
 110         if (!(dev->priv_flags & IFF_WAN_HDLC))
 111                 return NOTIFY_DONE; /* not an HDLC device */
 112
 113         if (event != NETDEV_CHANGE)
 114                 return NOTIFY_DONE; /* Only interested in carrier changes */
 115
 116         on = netif_carrier_ok(dev);
 117
 118 #ifdef DEBUG_LINK
 119         printk(KERN_DEBUG "%s: hdlc_device_event NETDEV_CHANGE, carrier %i\n",
 120                dev->name, on);
 121 #endif
 122
 123         hdlc = dev_to_hdlc(dev);
 124         spin_lock_irqsave(&hdlc->state_lock, flags);
 125
 126         if (hdlc->carrier == on)
 127                 goto carrier_exit; /* no change in DCD line level */
 128
 129         hdlc->carrier = on;
 130
 131         if (!hdlc->open)
 132                 goto carrier_exit;
 133
 134         if (hdlc->carrier) {
 135                 netdev_info(dev, "Carrier detected\n");
 136                 hdlc_proto_start(dev);
 137         } else {
 138                 netdev_info(dev, "Carrier lost\n");
 139                 hdlc_proto_stop(dev);
 140         }
 141
 142 carrier_exit:
 143         spin_unlock_irqrestore(&hdlc->state_lock, flags);
 144         return NOTIFY_DONE;
 145 }
 146
 147
 148
 149 /* Must be called by hardware driver when HDLC device is being opened */
 150 int hdlc_open(struct net_device *dev)
 151 {
 152         hdlc_device *hdlc = dev_to_hdlc(dev);
 153 #ifdef DEBUG_LINK
 154         printk(KERN_DEBUG "%s: hdlc_open() carrier %i open %i\n", dev->name,
 155                hdlc->carrier, hdlc->open);
 156 #endif
 157
 158         if (hdlc->proto == NULL)
 159                 return -ENOSYS; /* no protocol attached */
 160
 161         if (hdlc->proto->open) {
 162                 int result = hdlc->proto->open(dev);
 163                 if (result)
 164                         return result;
 165         }
 166
 167         spin_lock_irq(&hdlc->state_lock);
 168
 169         if (hdlc->carrier) {
 170                 netdev_info(dev, "Carrier detected\n");
 171                 hdlc_proto_start(dev);
 172         } else
 173                 netdev_info(dev, "No carrier\n");
 174
 175         hdlc->open = 1;
 176
 177         spin_unlock_irq(&hdlc->state_lock);
 178         return 0;
 179 }
 180
 181
 182
 183 /* Must be called by hardware driver when HDLC device is being closed */
 184 void hdlc_close(struct net_device *dev)
 185 {
 186         hdlc_device *hdlc = dev_to_hdlc(dev);
 187 #ifdef DEBUG_LINK
 188         printk(KERN_DEBUG "%s: hdlc_close() carrier %i open %i\n", dev->name,
 189                hdlc->carrier, hdlc->open);
 190 #endif
 191
 192         spin_lock_irq(&hdlc->state_lock);
 193
 194         hdlc->open = 0;
 195         if (hdlc->carrier)
 196                 hdlc_proto_stop(dev);
 197
 198         spin_unlock_irq(&hdlc->state_lock);
 199
 200         if (hdlc->proto->close)
 201                 hdlc->proto->close(dev);
 202 }
 203
 204
 205
 206 int hdlc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 207 {
 208         struct hdlc_proto *proto = first_proto;
 209         int result;
 210
 211         if (cmd != SIOCWANDEV)
 212                 return -EINVAL;
 213
 214         if (dev_to_hdlc(dev)->proto) {
 215                 result = dev_to_hdlc(dev)->proto->ioctl(dev, ifr);
 216                 if (result != -EINVAL)
 217                         return result;
 218         }
 219
 220         /* Not handled by currently attached protocol (if any) */
 221
 222         while (proto) {
 223                 if ((result = proto->ioctl(dev, ifr)) != -EINVAL)
 224                         return result;
 225                 proto = proto->next;
 226         }
 227         return -EINVAL;
 228 }
 229
 230 static const struct header_ops hdlc_null_ops;
 231
 232 static void hdlc_setup_dev(struct net_device *dev)
 233 {
 234         /* Re-init all variables changed by HDLC protocol drivers,
 235          * including ether_setup() called from hdlc_raw_eth.c.
 236          */
 237         dev->flags               = IFF_POINTOPOINT | IFF_NOARP;
 238         dev->priv_flags          = IFF_WAN_HDLC;
 239         dev->mtu                 = HDLC_MAX_MTU;
 240         dev->min_mtu             = 68;
 241         dev->max_mtu             = HDLC_MAX_MTU;
 242         dev->type                = ARPHRD_RAWHDLC;
 243         dev->hard_header_len     = 16;
 244         dev->addr_len            = 0;
 245         dev->header_ops          = &hdlc_null_ops;
 246 }
 247
 248 static void hdlc_setup(struct net_device *dev)
 249 {
 250         hdlc_device *hdlc = dev_to_hdlc(dev);
 251
 252         hdlc_setup_dev(dev);
 253         hdlc->carrier = 1;
 254         hdlc->open = 0;
 255         spin_lock_init(&hdlc->state_lock);
 256 }
 257
 258 struct net_device *alloc_hdlcdev(void *priv)
 259 {
 260         struct net_device *dev;
 261         dev = alloc_netdev(sizeof(struct hdlc_device), "hdlc%d",
 262                            NET_NAME_UNKNOWN, 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         detach_hdlc_protocol(dev);
 272         unregister_netdevice(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         int err;
 282
 283         err = detach_hdlc_protocol(dev);
 284         if (err)
 285                 return err;
 286
 287         if (!try_module_get(proto->module))
 288                 return -ENOSYS;
 289
 290         if (size) {
 291                 dev_to_hdlc(dev)->state = kmalloc(size, GFP_KERNEL);
 292                 if (dev_to_hdlc(dev)->state == NULL) {
 293                         module_put(proto->module);
 294                         return -ENOBUFS;
 295                 }
 296         }
 297         dev_to_hdlc(dev)->proto = proto;
 298
 299         return 0;
 300 }
 301
 302
 303 int detach_hdlc_protocol(struct net_device *dev)
 304 {
 305         hdlc_device *hdlc = dev_to_hdlc(dev);
 306         int err;
 307
 308         if (hdlc->proto) {
 309                 err = call_netdevice_notifiers(NETDEV_PRE_TYPE_CHANGE, dev);
 310                 err = notifier_to_errno(err);
 311                 if (err) {
 312                         netdev_err(dev, "Refused to change device type\n");
 313                         return err;
 314                 }
 315
 316                 if (hdlc->proto->detach)
 317                         hdlc->proto->detach(dev);
 318                 module_put(hdlc->proto->module);
 319                 hdlc->proto = NULL;
 320         }
 321         kfree(hdlc->state);
 322         hdlc->state = NULL;
 323         hdlc_setup_dev(dev);
 324
 325         return 0;
 326 }
 327
 328
 329 void register_hdlc_protocol(struct hdlc_proto *proto)
 330 {
 331         rtnl_lock();
 332         proto->next = first_proto;
 333         first_proto = proto;
 334         rtnl_unlock();
 335 }
 336
 337
 338 void unregister_hdlc_protocol(struct hdlc_proto *proto)
 339 {
 340         struct hdlc_proto **p;
 341
 342         rtnl_lock();
 343         p = &first_proto;
 344         while (*p != proto) {
 345                 BUG_ON(!*p);
 346                 p = &((*p)->next);
 347         }
 348         *p = proto->next;
 349         rtnl_unlock();
 350 }
 351
 352
 353
 354 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
 355 MODULE_DESCRIPTION("HDLC support module");
 356 MODULE_LICENSE("GPL v2");
 357
 358 EXPORT_SYMBOL(hdlc_start_xmit);
 359 EXPORT_SYMBOL(hdlc_open);
 360 EXPORT_SYMBOL(hdlc_close);
 361 EXPORT_SYMBOL(hdlc_ioctl);
 362 EXPORT_SYMBOL(alloc_hdlcdev);
 363 EXPORT_SYMBOL(unregister_hdlc_device);
 364 EXPORT_SYMBOL(register_hdlc_protocol);
 365 EXPORT_SYMBOL(unregister_hdlc_protocol);
 366 EXPORT_SYMBOL(attach_hdlc_protocol);
 367 EXPORT_SYMBOL(detach_hdlc_protocol);
 368
 369 static struct packet_type hdlc_packet_type __read_mostly = {
 370         .type = cpu_to_be16(ETH_P_HDLC),
 371         .func = hdlc_rcv,
 372 };
 373
 374
 375 static struct notifier_block hdlc_notifier = {
 376         .notifier_call = hdlc_device_event,
 377 };
 378
 379
 380 static int __init hdlc_module_init(void)
 381 {
 382         int result;
 383
 384         pr_info("%s\n", version);
 385         if ((result = register_netdevice_notifier(&hdlc_notifier)) != 0)
 386                 return result;
 387         dev_add_pack(&hdlc_packet_type);
 388         return 0;
 389 }
 390
 391
 392
 393 static void __exit hdlc_module_exit(void)
 394 {
 395         dev_remove_pack(&hdlc_packet_type);
 396         unregister_netdevice_notifier(&hdlc_notifier);
 397 }
 398
 399
 400 module_init(hdlc_module_init);
 401 module_exit(hdlc_module_exit);