drivers/net/wan/hdlc.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Generic HDLC support routines for Linux
   4  *
   5  * Copyright (C) 1999 - 2008 Krzysztof Halasa <khc@pm.waw.pl>
   6  *
   7  * Currently supported:
   8  *      * raw IP-in-HDLC
   9  *      * Cisco HDLC
  10  *      * Frame Relay with ANSI or CCITT LMI (both user and network side)
  11  *      * PPP
  12  *      * X.25
  13  *
  14  * Use sethdlc utility to set line parameters, protocol and PVCs
  15  *
  16  * How does it work:
  17  * - proto->open(), close(), start(), stop() calls are serialized.
  18  *   The order is: open, [ start, stop ... ] close ...
  19  * - proto->start() and stop() are called with spin_lock_irq held.
  20  */
  21
  22 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  23
  24 #include <linux/errno.h>
  25 #include <linux/hdlc.h>
  26 #include <linux/if_arp.h>
  27 #include <linux/inetdevice.h>
  28 #include <linux/init.h>
  29 #include <linux/kernel.h>
  30 #include <linux/module.h>
  31 #include <linux/notifier.h>
  32 #include <linux/pkt_sched.h>
  33 #include <linux/poll.h>
  34 #include <linux/rtnetlink.h>
  35 #include <linux/skbuff.h>
  36 #include <linux/slab.h>
  37 #include <net/net_namespace.h>
  38
  39
  40 static const char* version = "HDLC support module revision 1.22";
  41
  42 #undef DEBUG_LINK
  43
  44 static struct hdlc_proto *first_proto;
  45
  46 static int hdlc_rcv(struct sk_buff *skb, struct net_device *dev,
  47                     struct packet_type *p, struct net_device *orig_dev)
  48 {
  49         struct hdlc_device *hdlc = dev_to_hdlc(dev);
  50
  51         if (!net_eq(dev_net(dev), &init_net)) {
  52                 kfree_skb(skb);
  53                 return 0;
  54         }
  55
  56         BUG_ON(!hdlc->proto->netif_rx);
  57         return hdlc->proto->netif_rx(skb);
  58 }
  59
  60 netdev_tx_t hdlc_start_xmit(struct sk_buff *skb, struct net_device *dev)
  61 {
  62         hdlc_device *hdlc = dev_to_hdlc(dev);
  63
  64         if (hdlc->proto->xmit)
  65                 return hdlc->proto->xmit(skb, dev);
  66
  67         return hdlc->xmit(skb, dev); /* call hardware driver directly */
  68 }
  69
  70 static inline void hdlc_proto_start(struct net_device *dev)
  71 {
  72         hdlc_device *hdlc = dev_to_hdlc(dev);
  73         if (hdlc->proto->start)
  74                 hdlc->proto->start(dev);
  75 }
  76
  77
  78
  79 static inline void hdlc_proto_stop(struct net_device *dev)
  80 {
  81         hdlc_device *hdlc = dev_to_hdlc(dev);
  82         if (hdlc->proto->stop)
  83                 hdlc->proto->stop(dev);
  84 }
  85
  86
  87
  88 static int hdlc_device_event(struct notifier_block *this, unsigned long event,
  89                              void *ptr)
  90 {
  91         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
  92         hdlc_device *hdlc;
  93         unsigned long flags;
  94         int on;
  95
  96         if (!net_eq(dev_net(dev), &init_net))
  97                 return NOTIFY_DONE;
  98
  99         if (!(dev->priv_flags & IFF_WAN_HDLC))
 100                 return NOTIFY_DONE; /* not an HDLC device */
 101
 102         if (event != NETDEV_CHANGE)
 103                 return NOTIFY_DONE; /* Only interested in carrier changes */
 104
 105         on = netif_carrier_ok(dev);
 106
 107 #ifdef DEBUG_LINK
 108         printk(KERN_DEBUG "%s: hdlc_device_event NETDEV_CHANGE, carrier %i\n",
 109                dev->name, on);
 110 #endif
 111
 112         hdlc = dev_to_hdlc(dev);
 113         spin_lock_irqsave(&hdlc->state_lock, flags);
 114
 115         if (hdlc->carrier == on)
 116                 goto carrier_exit; /* no change in DCD line level */
 117
 118         hdlc->carrier = on;
 119
 120         if (!hdlc->open)
 121                 goto carrier_exit;
 122
 123         if (hdlc->carrier) {
 124                 netdev_info(dev, "Carrier detected\n");
 125                 hdlc_proto_start(dev);
 126         } else {
 127                 netdev_info(dev, "Carrier lost\n");
 128                 hdlc_proto_stop(dev);
 129         }
 130
 131 carrier_exit:
 132         spin_unlock_irqrestore(&hdlc->state_lock, flags);
 133         return NOTIFY_DONE;
 134 }
 135
 136
 137
 138 /* Must be called by hardware driver when HDLC device is being opened */
 139 int hdlc_open(struct net_device *dev)
 140 {
 141         hdlc_device *hdlc = dev_to_hdlc(dev);
 142 #ifdef DEBUG_LINK
 143         printk(KERN_DEBUG "%s: hdlc_open() carrier %i open %i\n", dev->name,
 144                hdlc->carrier, hdlc->open);
 145 #endif
 146
 147         if (hdlc->proto == NULL)
 148                 return -ENOSYS; /* no protocol attached */
 149
 150         if (hdlc->proto->open) {
 151                 int result = hdlc->proto->open(dev);
 152                 if (result)
 153                         return result;
 154         }
 155
 156         spin_lock_irq(&hdlc->state_lock);
 157
 158         if (hdlc->carrier) {
 159                 netdev_info(dev, "Carrier detected\n");
 160                 hdlc_proto_start(dev);
 161         } else
 162                 netdev_info(dev, "No carrier\n");
 163
 164         hdlc->open = 1;
 165
 166         spin_unlock_irq(&hdlc->state_lock);
 167         return 0;
 168 }
 169
 170
 171
 172 /* Must be called by hardware driver when HDLC device is being closed */
 173 void hdlc_close(struct net_device *dev)
 174 {
 175         hdlc_device *hdlc = dev_to_hdlc(dev);
 176 #ifdef DEBUG_LINK
 177         printk(KERN_DEBUG "%s: hdlc_close() carrier %i open %i\n", dev->name,
 178                hdlc->carrier, hdlc->open);
 179 #endif
 180
 181         spin_lock_irq(&hdlc->state_lock);
 182
 183         hdlc->open = 0;
 184         if (hdlc->carrier)
 185                 hdlc_proto_stop(dev);
 186
 187         spin_unlock_irq(&hdlc->state_lock);
 188
 189         if (hdlc->proto->close)
 190                 hdlc->proto->close(dev);
 191 }
 192
 193
 194
 195 int hdlc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 196 {
 197         struct hdlc_proto *proto = first_proto;
 198         int result;
 199
 200         if (cmd != SIOCWANDEV)
 201                 return -EINVAL;
 202
 203         if (dev_to_hdlc(dev)->proto) {
 204                 result = dev_to_hdlc(dev)->proto->ioctl(dev, ifr);
 205                 if (result != -EINVAL)
 206                         return result;
 207         }
 208
 209         /* Not handled by currently attached protocol (if any) */
 210
 211         while (proto) {
 212                 if ((result = proto->ioctl(dev, ifr)) != -EINVAL)
 213                         return result;
 214                 proto = proto->next;
 215         }
 216         return -EINVAL;
 217 }
 218
 219 static const struct header_ops hdlc_null_ops;
 220
 221 static void hdlc_setup_dev(struct net_device *dev)
 222 {
 223         /* Re-init all variables changed by HDLC protocol drivers,
 224          * including ether_setup() called from hdlc_raw_eth.c.
 225          */
 226         dev->flags               = IFF_POINTOPOINT | IFF_NOARP;
 227         dev->priv_flags          = IFF_WAN_HDLC;
 228         dev->mtu                 = HDLC_MAX_MTU;
 229         dev->min_mtu             = 68;
 230         dev->max_mtu             = HDLC_MAX_MTU;
 231         dev->type                = ARPHRD_RAWHDLC;
 232         dev->hard_header_len     = 16;
 233         dev->addr_len            = 0;
 234         dev->header_ops          = &hdlc_null_ops;
 235 }
 236
 237 static void hdlc_setup(struct net_device *dev)
 238 {
 239         hdlc_device *hdlc = dev_to_hdlc(dev);
 240
 241         hdlc_setup_dev(dev);
 242         hdlc->carrier = 1;
 243         hdlc->open = 0;
 244         spin_lock_init(&hdlc->state_lock);
 245 }
 246
 247 struct net_device *alloc_hdlcdev(void *priv)
 248 {
 249         struct net_device *dev;
 250         dev = alloc_netdev(sizeof(struct hdlc_device), "hdlc%d",
 251                            NET_NAME_UNKNOWN, hdlc_setup);
 252         if (dev)
 253                 dev_to_hdlc(dev)->priv = priv;
 254         return dev;
 255 }
 256
 257 void unregister_hdlc_device(struct net_device *dev)
 258 {
 259         rtnl_lock();
 260         detach_hdlc_protocol(dev);
 261         unregister_netdevice(dev);
 262         rtnl_unlock();
 263 }
 264
 265
 266
 267 int attach_hdlc_protocol(struct net_device *dev, struct hdlc_proto *proto,
 268                          size_t size)
 269 {
 270         int err;
 271
 272         err = detach_hdlc_protocol(dev);
 273         if (err)
 274                 return err;
 275
 276         if (!try_module_get(proto->module))
 277                 return -ENOSYS;
 278
 279         if (size) {
 280                 dev_to_hdlc(dev)->state = kmalloc(size, GFP_KERNEL);
 281                 if (dev_to_hdlc(dev)->state == NULL) {
 282                         module_put(proto->module);
 283                         return -ENOBUFS;
 284                 }
 285         }
 286         dev_to_hdlc(dev)->proto = proto;
 287
 288         return 0;
 289 }
 290
 291
 292 int detach_hdlc_protocol(struct net_device *dev)
 293 {
 294         hdlc_device *hdlc = dev_to_hdlc(dev);
 295         int err;
 296
 297         if (hdlc->proto) {
 298                 err = call_netdevice_notifiers(NETDEV_PRE_TYPE_CHANGE, dev);
 299                 err = notifier_to_errno(err);
 300                 if (err) {
 301                         netdev_err(dev, "Refused to change device type\n");
 302                         return err;
 303                 }
 304
 305                 if (hdlc->proto->detach)
 306                         hdlc->proto->detach(dev);
 307                 module_put(hdlc->proto->module);
 308                 hdlc->proto = NULL;
 309         }
 310         kfree(hdlc->state);
 311         hdlc->state = NULL;
 312         hdlc_setup_dev(dev);
 313
 314         return 0;
 315 }
 316
 317
 318 void register_hdlc_protocol(struct hdlc_proto *proto)
 319 {
 320         rtnl_lock();
 321         proto->next = first_proto;
 322         first_proto = proto;
 323         rtnl_unlock();
 324 }
 325
 326
 327 void unregister_hdlc_protocol(struct hdlc_proto *proto)
 328 {
 329         struct hdlc_proto **p;
 330
 331         rtnl_lock();
 332         p = &first_proto;
 333         while (*p != proto) {
 334                 BUG_ON(!*p);
 335                 p = &((*p)->next);
 336         }
 337         *p = proto->next;
 338         rtnl_unlock();
 339 }
 340
 341
 342
 343 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
 344 MODULE_DESCRIPTION("HDLC support module");
 345 MODULE_LICENSE("GPL v2");
 346
 347 EXPORT_SYMBOL(hdlc_start_xmit);
 348 EXPORT_SYMBOL(hdlc_open);
 349 EXPORT_SYMBOL(hdlc_close);
 350 EXPORT_SYMBOL(hdlc_ioctl);
 351 EXPORT_SYMBOL(alloc_hdlcdev);
 352 EXPORT_SYMBOL(unregister_hdlc_device);
 353 EXPORT_SYMBOL(register_hdlc_protocol);
 354 EXPORT_SYMBOL(unregister_hdlc_protocol);
 355 EXPORT_SYMBOL(attach_hdlc_protocol);
 356 EXPORT_SYMBOL(detach_hdlc_protocol);
 357
 358 static struct packet_type hdlc_packet_type __read_mostly = {
 359         .type = cpu_to_be16(ETH_P_HDLC),
 360         .func = hdlc_rcv,
 361 };
 362
 363
 364 static struct notifier_block hdlc_notifier = {
 365         .notifier_call = hdlc_device_event,
 366 };
 367
 368
 369 static int __init hdlc_module_init(void)
 370 {
 371         int result;
 372
 373         pr_info("%s\n", version);
 374         if ((result = register_netdevice_notifier(&hdlc_notifier)) != 0)
 375                 return result;
 376         dev_add_pack(&hdlc_packet_type);
 377         return 0;
 378 }
 379
 380
 381
 382 static void __exit hdlc_module_exit(void)
 383 {
 384         dev_remove_pack(&hdlc_packet_type);
 385         unregister_netdevice_notifier(&hdlc_notifier);
 386 }
 387
 388
 389 module_init(hdlc_module_init);
 390 module_exit(hdlc_module_exit);