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 = dev_to_hdlc(dev);
  53
  54         if (!net_eq(dev_net(dev), &init_net)) {
  55                 kfree_skb(skb);
  56                 return 0;
  57         }
  58
  59         BUG_ON(!hdlc->proto->netif_rx);
  60         return hdlc->proto->netif_rx(skb);
  61 }
  62
  63 netdev_tx_t hdlc_start_xmit(struct sk_buff *skb, struct net_device *dev)
  64 {
  65         hdlc_device *hdlc = dev_to_hdlc(dev);
  66
  67         if (hdlc->proto->xmit)
  68                 return hdlc->proto->xmit(skb, dev);
  69
  70         return hdlc->xmit(skb, dev); /* call hardware driver directly */
  71 }
  72
  73 static inline void hdlc_proto_start(struct net_device *dev)
  74 {
  75         hdlc_device *hdlc = dev_to_hdlc(dev);
  76         if (hdlc->proto->start)
  77                 hdlc->proto->start(dev);
  78 }
  79
  80
  81
  82 static inline void hdlc_proto_stop(struct net_device *dev)
  83 {
  84         hdlc_device *hdlc = dev_to_hdlc(dev);
  85         if (hdlc->proto->stop)
  86                 hdlc->proto->stop(dev);
  87 }
  88
  89
  90
  91 static int hdlc_device_event(struct notifier_block *this, unsigned long event,
  92                              void *ptr)
  93 {
  94         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
  95         hdlc_device *hdlc;
  96         unsigned long flags;
  97         int on;
  98
  99         if (!net_eq(dev_net(dev), &init_net))
 100                 return NOTIFY_DONE;
 101
 102         if (!(dev->priv_flags & IFF_WAN_HDLC))
 103                 return NOTIFY_DONE; /* not an HDLC device */
 104
 105         if (event != NETDEV_CHANGE)
 106                 return NOTIFY_DONE; /* Only interested in carrier changes */
 107
 108         on = netif_carrier_ok(dev);
 109
 110 #ifdef DEBUG_LINK
 111         printk(KERN_DEBUG "%s: hdlc_device_event NETDEV_CHANGE, carrier %i\n",
 112                dev->name, on);
 113 #endif
 114
 115         hdlc = dev_to_hdlc(dev);
 116         spin_lock_irqsave(&hdlc->state_lock, flags);
 117
 118         if (hdlc->carrier == on)
 119                 goto carrier_exit; /* no change in DCD line level */
 120
 121         hdlc->carrier = on;
 122
 123         if (!hdlc->open)
 124                 goto carrier_exit;
 125
 126         if (hdlc->carrier) {
 127                 netdev_info(dev, "Carrier detected\n");
 128                 hdlc_proto_start(dev);
 129         } else {
 130                 netdev_info(dev, "Carrier lost\n");
 131                 hdlc_proto_stop(dev);
 132         }
 133
 134 carrier_exit:
 135         spin_unlock_irqrestore(&hdlc->state_lock, flags);
 136         return NOTIFY_DONE;
 137 }
 138
 139
 140
 141 /* Must be called by hardware driver when HDLC device is being opened */
 142 int hdlc_open(struct net_device *dev)
 143 {
 144         hdlc_device *hdlc = dev_to_hdlc(dev);
 145 #ifdef DEBUG_LINK
 146         printk(KERN_DEBUG "%s: hdlc_open() carrier %i open %i\n", dev->name,
 147                hdlc->carrier, hdlc->open);
 148 #endif
 149
 150         if (hdlc->proto == NULL)
 151                 return -ENOSYS; /* no protocol attached */
 152
 153         if (hdlc->proto->open) {
 154                 int result = hdlc->proto->open(dev);
 155                 if (result)
 156                         return result;
 157         }
 158
 159         spin_lock_irq(&hdlc->state_lock);
 160
 161         if (hdlc->carrier) {
 162                 netdev_info(dev, "Carrier detected\n");
 163                 hdlc_proto_start(dev);
 164         } else
 165                 netdev_info(dev, "No carrier\n");
 166
 167         hdlc->open = 1;
 168
 169         spin_unlock_irq(&hdlc->state_lock);
 170         return 0;
 171 }
 172
 173
 174
 175 /* Must be called by hardware driver when HDLC device is being closed */
 176 void hdlc_close(struct net_device *dev)
 177 {
 178         hdlc_device *hdlc = dev_to_hdlc(dev);
 179 #ifdef DEBUG_LINK
 180         printk(KERN_DEBUG "%s: hdlc_close() carrier %i open %i\n", dev->name,
 181                hdlc->carrier, hdlc->open);
 182 #endif
 183
 184         spin_lock_irq(&hdlc->state_lock);
 185
 186         hdlc->open = 0;
 187         if (hdlc->carrier)
 188                 hdlc_proto_stop(dev);
 189
 190         spin_unlock_irq(&hdlc->state_lock);
 191
 192         if (hdlc->proto->close)
 193                 hdlc->proto->close(dev);
 194 }
 195
 196
 197
 198 int hdlc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 199 {
 200         struct hdlc_proto *proto = first_proto;
 201         int result;
 202
 203         if (cmd != SIOCWANDEV)
 204                 return -EINVAL;
 205
 206         if (dev_to_hdlc(dev)->proto) {
 207                 result = dev_to_hdlc(dev)->proto->ioctl(dev, ifr);
 208                 if (result != -EINVAL)
 209                         return result;
 210         }
 211
 212         /* Not handled by currently attached protocol (if any) */
 213
 214         while (proto) {
 215                 if ((result = proto->ioctl(dev, ifr)) != -EINVAL)
 216                         return result;
 217                 proto = proto->next;
 218         }
 219         return -EINVAL;
 220 }
 221
 222 static const struct header_ops hdlc_null_ops;
 223
 224 static void hdlc_setup_dev(struct net_device *dev)
 225 {
 226         /* Re-init all variables changed by HDLC protocol drivers,
 227          * including ether_setup() called from hdlc_raw_eth.c.
 228          */
 229         dev->flags               = IFF_POINTOPOINT | IFF_NOARP;
 230         dev->priv_flags          = IFF_WAN_HDLC;
 231         dev->mtu                 = HDLC_MAX_MTU;
 232         dev->min_mtu             = 68;
 233         dev->max_mtu             = HDLC_MAX_MTU;
 234         dev->type                = ARPHRD_RAWHDLC;
 235         dev->hard_header_len     = 16;
 236         dev->addr_len            = 0;
 237         dev->header_ops          = &hdlc_null_ops;
 238 }
 239
 240 static void hdlc_setup(struct net_device *dev)
 241 {
 242         hdlc_device *hdlc = dev_to_hdlc(dev);
 243
 244         hdlc_setup_dev(dev);
 245         hdlc->carrier = 1;
 246         hdlc->open = 0;
 247         spin_lock_init(&hdlc->state_lock);
 248 }
 249
 250 struct net_device *alloc_hdlcdev(void *priv)
 251 {
 252         struct net_device *dev;
 253         dev = alloc_netdev(sizeof(struct hdlc_device), "hdlc%d",
 254                            NET_NAME_UNKNOWN, hdlc_setup);
 255         if (dev)
 256                 dev_to_hdlc(dev)->priv = priv;
 257         return dev;
 258 }
 259
 260 void unregister_hdlc_device(struct net_device *dev)
 261 {
 262         rtnl_lock();
 263         detach_hdlc_protocol(dev);
 264         unregister_netdevice(dev);
 265         rtnl_unlock();
 266 }
 267
 268
 269
 270 int attach_hdlc_protocol(struct net_device *dev, struct hdlc_proto *proto,
 271                          size_t size)
 272 {
 273         int err;
 274
 275         err = detach_hdlc_protocol(dev);
 276         if (err)
 277                 return err;
 278
 279         if (!try_module_get(proto->module))
 280                 return -ENOSYS;
 281
 282         if (size) {
 283                 dev_to_hdlc(dev)->state = kmalloc(size, GFP_KERNEL);
 284                 if (dev_to_hdlc(dev)->state == NULL) {
 285                         module_put(proto->module);
 286                         return -ENOBUFS;
 287                 }
 288         }
 289         dev_to_hdlc(dev)->proto = proto;
 290
 291         return 0;
 292 }
 293
 294
 295 int detach_hdlc_protocol(struct net_device *dev)
 296 {
 297         hdlc_device *hdlc = dev_to_hdlc(dev);
 298         int err;
 299
 300         if (hdlc->proto) {
 301                 err = call_netdevice_notifiers(NETDEV_PRE_TYPE_CHANGE, dev);
 302                 err = notifier_to_errno(err);
 303                 if (err) {
 304                         netdev_err(dev, "Refused to change device type\n");
 305                         return err;
 306                 }
 307
 308                 if (hdlc->proto->detach)
 309                         hdlc->proto->detach(dev);
 310                 module_put(hdlc->proto->module);
 311                 hdlc->proto = NULL;
 312         }
 313         kfree(hdlc->state);
 314         hdlc->state = NULL;
 315         hdlc_setup_dev(dev);
 316
 317         return 0;
 318 }
 319
 320
 321 void register_hdlc_protocol(struct hdlc_proto *proto)
 322 {
 323         rtnl_lock();
 324         proto->next = first_proto;
 325         first_proto = proto;
 326         rtnl_unlock();
 327 }
 328
 329
 330 void unregister_hdlc_protocol(struct hdlc_proto *proto)
 331 {
 332         struct hdlc_proto **p;
 333
 334         rtnl_lock();
 335         p = &first_proto;
 336         while (*p != proto) {
 337                 BUG_ON(!*p);
 338                 p = &((*p)->next);
 339         }
 340         *p = proto->next;
 341         rtnl_unlock();
 342 }
 343
 344
 345
 346 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
 347 MODULE_DESCRIPTION("HDLC support module");
 348 MODULE_LICENSE("GPL v2");
 349
 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);