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;
  50
  51         /* First make sure "dev" is an HDLC device */
  52         if (!(dev->priv_flags & IFF_WAN_HDLC)) {
  53                 kfree_skb(skb);
  54                 return NET_RX_SUCCESS;
  55         }
  56
  57         hdlc = dev_to_hdlc(dev);
  58
  59         if (!net_eq(dev_net(dev), &init_net)) {
  60                 kfree_skb(skb);
  61                 return 0;
  62         }
  63
  64         BUG_ON(!hdlc->proto->netif_rx);
  65         return hdlc->proto->netif_rx(skb);
  66 }
  67
  68 netdev_tx_t hdlc_start_xmit(struct sk_buff *skb, struct net_device *dev)
  69 {
  70         hdlc_device *hdlc = dev_to_hdlc(dev);
  71
  72         if (hdlc->proto->xmit)
  73                 return hdlc->proto->xmit(skb, dev);
  74
  75         return hdlc->xmit(skb, dev); /* call hardware driver directly */
  76 }
  77
  78 static inline void hdlc_proto_start(struct net_device *dev)
  79 {
  80         hdlc_device *hdlc = dev_to_hdlc(dev);
  81         if (hdlc->proto->start)
  82                 hdlc->proto->start(dev);
  83 }
  84
  85
  86
  87 static inline void hdlc_proto_stop(struct net_device *dev)
  88 {
  89         hdlc_device *hdlc = dev_to_hdlc(dev);
  90         if (hdlc->proto->stop)
  91                 hdlc->proto->stop(dev);
  92 }
  93
  94
  95
  96 static int hdlc_device_event(struct notifier_block *this, unsigned long event,
  97                              void *ptr)
  98 {
  99         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
 100         hdlc_device *hdlc;
 101         unsigned long flags;
 102         int on;
 103
 104         if (!net_eq(dev_net(dev), &init_net))
 105                 return NOTIFY_DONE;
 106
 107         if (!(dev->priv_flags & IFF_WAN_HDLC))
 108                 return NOTIFY_DONE; /* not an HDLC device */
 109
 110         if (event != NETDEV_CHANGE)
 111                 return NOTIFY_DONE; /* Only interested in carrier changes */
 112
 113         on = netif_carrier_ok(dev);
 114
 115 #ifdef DEBUG_LINK
 116         printk(KERN_DEBUG "%s: hdlc_device_event NETDEV_CHANGE, carrier %i\n",
 117                dev->name, on);
 118 #endif
 119
 120         hdlc = dev_to_hdlc(dev);
 121         spin_lock_irqsave(&hdlc->state_lock, flags);
 122
 123         if (hdlc->carrier == on)
 124                 goto carrier_exit; /* no change in DCD line level */
 125
 126         hdlc->carrier = on;
 127
 128         if (!hdlc->open)
 129                 goto carrier_exit;
 130
 131         if (hdlc->carrier) {
 132                 netdev_info(dev, "Carrier detected\n");
 133                 hdlc_proto_start(dev);
 134         } else {
 135                 netdev_info(dev, "Carrier lost\n");
 136                 hdlc_proto_stop(dev);
 137         }
 138
 139 carrier_exit:
 140         spin_unlock_irqrestore(&hdlc->state_lock, flags);
 141         return NOTIFY_DONE;
 142 }
 143
 144
 145
 146 /* Must be called by hardware driver when HDLC device is being opened */
 147 int hdlc_open(struct net_device *dev)
 148 {
 149         hdlc_device *hdlc = dev_to_hdlc(dev);
 150 #ifdef DEBUG_LINK
 151         printk(KERN_DEBUG "%s: hdlc_open() carrier %i open %i\n", dev->name,
 152                hdlc->carrier, hdlc->open);
 153 #endif
 154
 155         if (hdlc->proto == NULL)
 156                 return -ENOSYS; /* no protocol attached */
 157
 158         if (hdlc->proto->open) {
 159                 int result = hdlc->proto->open(dev);
 160                 if (result)
 161                         return result;
 162         }
 163
 164         spin_lock_irq(&hdlc->state_lock);
 165
 166         if (hdlc->carrier) {
 167                 netdev_info(dev, "Carrier detected\n");
 168                 hdlc_proto_start(dev);
 169         } else
 170                 netdev_info(dev, "No carrier\n");
 171
 172         hdlc->open = 1;
 173
 174         spin_unlock_irq(&hdlc->state_lock);
 175         return 0;
 176 }
 177
 178
 179
 180 /* Must be called by hardware driver when HDLC device is being closed */
 181 void hdlc_close(struct net_device *dev)
 182 {
 183         hdlc_device *hdlc = dev_to_hdlc(dev);
 184 #ifdef DEBUG_LINK
 185         printk(KERN_DEBUG "%s: hdlc_close() carrier %i open %i\n", dev->name,
 186                hdlc->carrier, hdlc->open);
 187 #endif
 188
 189         spin_lock_irq(&hdlc->state_lock);
 190
 191         hdlc->open = 0;
 192         if (hdlc->carrier)
 193                 hdlc_proto_stop(dev);
 194
 195         spin_unlock_irq(&hdlc->state_lock);
 196
 197         if (hdlc->proto->close)
 198                 hdlc->proto->close(dev);
 199 }
 200
 201
 202
 203 int hdlc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 204 {
 205         struct hdlc_proto *proto = first_proto;
 206         int result;
 207
 208         if (cmd != SIOCWANDEV)
 209                 return -EINVAL;
 210
 211         if (dev_to_hdlc(dev)->proto) {
 212                 result = dev_to_hdlc(dev)->proto->ioctl(dev, ifr);
 213                 if (result != -EINVAL)
 214                         return result;
 215         }
 216
 217         /* Not handled by currently attached protocol (if any) */
 218
 219         while (proto) {
 220                 if ((result = proto->ioctl(dev, ifr)) != -EINVAL)
 221                         return result;
 222                 proto = proto->next;
 223         }
 224         return -EINVAL;
 225 }
 226
 227 static const struct header_ops hdlc_null_ops;
 228
 229 static void hdlc_setup_dev(struct net_device *dev)
 230 {
 231         /* Re-init all variables changed by HDLC protocol drivers,
 232          * including ether_setup() called from hdlc_raw_eth.c.
 233          */
 234         dev->flags               = IFF_POINTOPOINT | IFF_NOARP;
 235         dev->priv_flags          = IFF_WAN_HDLC;
 236         dev->mtu                 = HDLC_MAX_MTU;
 237         dev->min_mtu             = 68;
 238         dev->max_mtu             = HDLC_MAX_MTU;
 239         dev->type                = ARPHRD_RAWHDLC;
 240         dev->hard_header_len     = 0;
 241         dev->needed_headroom     = 0;
 242         dev->addr_len            = 0;
 243         dev->header_ops          = &hdlc_null_ops;
 244 }
 245
 246 static void hdlc_setup(struct net_device *dev)
 247 {
 248         hdlc_device *hdlc = dev_to_hdlc(dev);
 249
 250         hdlc_setup_dev(dev);
 251         hdlc->carrier = 1;
 252         hdlc->open = 0;
 253         spin_lock_init(&hdlc->state_lock);
 254 }
 255
 256 struct net_device *alloc_hdlcdev(void *priv)
 257 {
 258         struct net_device *dev;
 259         dev = alloc_netdev(sizeof(struct hdlc_device), "hdlc%d",
 260                            NET_NAME_UNKNOWN, hdlc_setup);
 261         if (dev)
 262                 dev_to_hdlc(dev)->priv = priv;
 263         return dev;
 264 }
 265
 266 void unregister_hdlc_device(struct net_device *dev)
 267 {
 268         rtnl_lock();
 269         detach_hdlc_protocol(dev);
 270         unregister_netdevice(dev);
 271         rtnl_unlock();
 272 }
 273
 274
 275
 276 int attach_hdlc_protocol(struct net_device *dev, struct hdlc_proto *proto,
 277                          size_t size)
 278 {
 279         int err;
 280
 281         err = detach_hdlc_protocol(dev);
 282         if (err)
 283                 return err;
 284
 285         if (!try_module_get(proto->module))
 286                 return -ENOSYS;
 287
 288         if (size) {
 289                 dev_to_hdlc(dev)->state = kmalloc(size, GFP_KERNEL);
 290                 if (dev_to_hdlc(dev)->state == NULL) {
 291                         module_put(proto->module);
 292                         return -ENOBUFS;
 293                 }
 294         }
 295         dev_to_hdlc(dev)->proto = proto;
 296
 297         return 0;
 298 }
 299
 300
 301 int detach_hdlc_protocol(struct net_device *dev)
 302 {
 303         hdlc_device *hdlc = dev_to_hdlc(dev);
 304         int err;
 305
 306         if (hdlc->proto) {
 307                 err = call_netdevice_notifiers(NETDEV_PRE_TYPE_CHANGE, dev);
 308                 err = notifier_to_errno(err);
 309                 if (err) {
 310                         netdev_err(dev, "Refused to change device type\n");
 311                         return err;
 312                 }
 313
 314                 if (hdlc->proto->detach)
 315                         hdlc->proto->detach(dev);
 316                 module_put(hdlc->proto->module);
 317                 hdlc->proto = NULL;
 318         }
 319         kfree(hdlc->state);
 320         hdlc->state = NULL;
 321         hdlc_setup_dev(dev);
 322
 323         return 0;
 324 }
 325
 326
 327 void register_hdlc_protocol(struct hdlc_proto *proto)
 328 {
 329         rtnl_lock();
 330         proto->next = first_proto;
 331         first_proto = proto;
 332         rtnl_unlock();
 333 }
 334
 335
 336 void unregister_hdlc_protocol(struct hdlc_proto *proto)
 337 {
 338         struct hdlc_proto **p;
 339
 340         rtnl_lock();
 341         p = &first_proto;
 342         while (*p != proto) {
 343                 BUG_ON(!*p);
 344                 p = &((*p)->next);
 345         }
 346         *p = proto->next;
 347         rtnl_unlock();
 348 }
 349
 350
 351
 352 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
 353 MODULE_DESCRIPTION("HDLC support module");
 354 MODULE_LICENSE("GPL v2");
 355
 356 EXPORT_SYMBOL(hdlc_start_xmit);
 357 EXPORT_SYMBOL(hdlc_open);
 358 EXPORT_SYMBOL(hdlc_close);
 359 EXPORT_SYMBOL(hdlc_ioctl);
 360 EXPORT_SYMBOL(alloc_hdlcdev);
 361 EXPORT_SYMBOL(unregister_hdlc_device);
 362 EXPORT_SYMBOL(register_hdlc_protocol);
 363 EXPORT_SYMBOL(unregister_hdlc_protocol);
 364 EXPORT_SYMBOL(attach_hdlc_protocol);
 365 EXPORT_SYMBOL(detach_hdlc_protocol);
 366
 367 static struct packet_type hdlc_packet_type __read_mostly = {
 368         .type = cpu_to_be16(ETH_P_HDLC),
 369         .func = hdlc_rcv,
 370 };
 371
 372
 373 static struct notifier_block hdlc_notifier = {
 374         .notifier_call = hdlc_device_event,
 375 };
 376
 377
 378 static int __init hdlc_module_init(void)
 379 {
 380         int result;
 381
 382         pr_info("%s\n", version);
 383         if ((result = register_netdevice_notifier(&hdlc_notifier)) != 0)
 384                 return result;
 385         dev_add_pack(&hdlc_packet_type);
 386         return 0;
 387 }
 388
 389
 390
 391 static void __exit hdlc_module_exit(void)
 392 {
 393         dev_remove_pack(&hdlc_packet_type);
 394         unregister_netdevice_notifier(&hdlc_notifier);
 395 }
 396
 397
 398 module_init(hdlc_module_init);
 399 module_exit(hdlc_module_exit);