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 static const char *version = "HDLC support module revision 1.22";
  40
  41 #undef DEBUG_LINK
  42
  43 static struct hdlc_proto *first_proto;
  44
  45 static int hdlc_rcv(struct sk_buff *skb, struct net_device *dev,
  46                     struct packet_type *p, struct net_device *orig_dev)
  47 {
  48         struct hdlc_device *hdlc;
  49
  50         /* First make sure "dev" is an HDLC device */
  51         if (!(dev->priv_flags & IFF_WAN_HDLC)) {
  52                 kfree_skb(skb);
  53                 return NET_RX_SUCCESS;
  54         }
  55
  56         hdlc = dev_to_hdlc(dev);
  57
  58         if (!net_eq(dev_net(dev), &init_net)) {
  59                 kfree_skb(skb);
  60                 return 0;
  61         }
  62
  63         BUG_ON(!hdlc->proto->netif_rx);
  64         return hdlc->proto->netif_rx(skb);
  65 }
  66
  67 netdev_tx_t hdlc_start_xmit(struct sk_buff *skb, struct net_device *dev)
  68 {
  69         hdlc_device *hdlc = dev_to_hdlc(dev);
  70
  71         if (hdlc->proto->xmit)
  72                 return hdlc->proto->xmit(skb, dev);
  73
  74         return hdlc->xmit(skb, dev); /* call hardware driver directly */
  75 }
  76 EXPORT_SYMBOL(hdlc_start_xmit);
  77
  78 static inline void hdlc_proto_start(struct net_device *dev)
  79 {
  80         hdlc_device *hdlc = dev_to_hdlc(dev);
  81
  82         if (hdlc->proto->start)
  83                 hdlc->proto->start(dev);
  84 }
  85
  86 static inline void hdlc_proto_stop(struct net_device *dev)
  87 {
  88         hdlc_device *hdlc = dev_to_hdlc(dev);
  89
  90         if (hdlc->proto->stop)
  91                 hdlc->proto->stop(dev);
  92 }
  93
  94 static int hdlc_device_event(struct notifier_block *this, unsigned long event,
  95                              void *ptr)
  96 {
  97         struct net_device *dev = netdev_notifier_info_to_dev(ptr);
  98         hdlc_device *hdlc;
  99         unsigned long flags;
 100         int on;
 101
 102         if (!net_eq(dev_net(dev), &init_net))
 103                 return NOTIFY_DONE;
 104
 105         if (!(dev->priv_flags & IFF_WAN_HDLC))
 106                 return NOTIFY_DONE; /* not an HDLC device */
 107
 108         if (event != NETDEV_CHANGE)
 109                 return NOTIFY_DONE; /* Only interested in carrier changes */
 110
 111         on = netif_carrier_ok(dev);
 112
 113 #ifdef DEBUG_LINK
 114         printk(KERN_DEBUG "%s: hdlc_device_event NETDEV_CHANGE, carrier %i\n",
 115                dev->name, on);
 116 #endif
 117
 118         hdlc = dev_to_hdlc(dev);
 119         spin_lock_irqsave(&hdlc->state_lock, flags);
 120
 121         if (hdlc->carrier == on)
 122                 goto carrier_exit; /* no change in DCD line level */
 123
 124         hdlc->carrier = on;
 125
 126         if (!hdlc->open)
 127                 goto carrier_exit;
 128
 129         if (hdlc->carrier) {
 130                 netdev_info(dev, "Carrier detected\n");
 131                 hdlc_proto_start(dev);
 132         } else {
 133                 netdev_info(dev, "Carrier lost\n");
 134                 hdlc_proto_stop(dev);
 135         }
 136
 137 carrier_exit:
 138         spin_unlock_irqrestore(&hdlc->state_lock, flags);
 139         return NOTIFY_DONE;
 140 }
 141
 142 /* Must be called by hardware driver when HDLC device is being opened */
 143 int hdlc_open(struct net_device *dev)
 144 {
 145         hdlc_device *hdlc = dev_to_hdlc(dev);
 146 #ifdef DEBUG_LINK
 147         printk(KERN_DEBUG "%s: hdlc_open() carrier %i open %i\n", dev->name,
 148                hdlc->carrier, hdlc->open);
 149 #endif
 150
 151         if (!hdlc->proto)
 152                 return -ENOSYS; /* no protocol attached */
 153
 154         if (hdlc->proto->open) {
 155                 int result = hdlc->proto->open(dev);
 156
 157                 if (result)
 158                         return result;
 159         }
 160
 161         spin_lock_irq(&hdlc->state_lock);
 162
 163         if (hdlc->carrier) {
 164                 netdev_info(dev, "Carrier detected\n");
 165                 hdlc_proto_start(dev);
 166         } else {
 167                 netdev_info(dev, "No carrier\n");
 168         }
 169
 170         hdlc->open = 1;
 171
 172         spin_unlock_irq(&hdlc->state_lock);
 173         return 0;
 174 }
 175 EXPORT_SYMBOL(hdlc_open);
 176
 177 /* Must be called by hardware driver when HDLC device is being closed */
 178 void hdlc_close(struct net_device *dev)
 179 {
 180         hdlc_device *hdlc = dev_to_hdlc(dev);
 181 #ifdef DEBUG_LINK
 182         printk(KERN_DEBUG "%s: hdlc_close() carrier %i open %i\n", dev->name,
 183                hdlc->carrier, hdlc->open);
 184 #endif
 185
 186         spin_lock_irq(&hdlc->state_lock);
 187
 188         hdlc->open = 0;
 189         if (hdlc->carrier)
 190                 hdlc_proto_stop(dev);
 191
 192         spin_unlock_irq(&hdlc->state_lock);
 193
 194         if (hdlc->proto->close)
 195                 hdlc->proto->close(dev);
 196 }
 197 EXPORT_SYMBOL(hdlc_close);
 198
 199 int hdlc_ioctl(struct net_device *dev, struct if_settings *ifs)
 200 {
 201         struct hdlc_proto *proto = first_proto;
 202         int result;
 203
 204         if (dev_to_hdlc(dev)->proto) {
 205                 result = dev_to_hdlc(dev)->proto->ioctl(dev, ifs);
 206                 if (result != -EINVAL)
 207                         return result;
 208         }
 209
 210         /* Not handled by currently attached protocol (if any) */
 211
 212         while (proto) {
 213                 result = proto->ioctl(dev, ifs);
 214                 if (result != -EINVAL)
 215                         return result;
 216                 proto = proto->next;
 217         }
 218         return -EINVAL;
 219 }
 220 EXPORT_SYMBOL(hdlc_ioctl);
 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     = 0;
 236         dev->needed_headroom     = 0;
 237         dev->addr_len            = 0;
 238         dev->header_ops          = &hdlc_null_ops;
 239 }
 240
 241 static void hdlc_setup(struct net_device *dev)
 242 {
 243         hdlc_device *hdlc = dev_to_hdlc(dev);
 244
 245         hdlc_setup_dev(dev);
 246         hdlc->carrier = 1;
 247         hdlc->open = 0;
 248         spin_lock_init(&hdlc->state_lock);
 249 }
 250
 251 struct net_device *alloc_hdlcdev(void *priv)
 252 {
 253         struct net_device *dev;
 254
 255         dev = alloc_netdev(sizeof(struct hdlc_device), "hdlc%d",
 256                            NET_NAME_UNKNOWN, hdlc_setup);
 257         if (dev)
 258                 dev_to_hdlc(dev)->priv = priv;
 259         return dev;
 260 }
 261 EXPORT_SYMBOL(alloc_hdlcdev);
 262
 263 void unregister_hdlc_device(struct net_device *dev)
 264 {
 265         rtnl_lock();
 266         detach_hdlc_protocol(dev);
 267         unregister_netdevice(dev);
 268         rtnl_unlock();
 269 }
 270 EXPORT_SYMBOL(unregister_hdlc_device);
 271
 272 int attach_hdlc_protocol(struct net_device *dev, struct hdlc_proto *proto,
 273                          size_t size)
 274 {
 275         int err;
 276
 277         err = detach_hdlc_protocol(dev);
 278         if (err)
 279                 return err;
 280
 281         if (!try_module_get(proto->module))
 282                 return -ENOSYS;
 283
 284         if (size) {
 285                 dev_to_hdlc(dev)->state = kmalloc(size, GFP_KERNEL);
 286                 if (!dev_to_hdlc(dev)->state) {
 287                         module_put(proto->module);
 288                         return -ENOBUFS;
 289                 }
 290         }
 291         dev_to_hdlc(dev)->proto = proto;
 292
 293         return 0;
 294 }
 295 EXPORT_SYMBOL(attach_hdlc_protocol);
 296
 297 int detach_hdlc_protocol(struct net_device *dev)
 298 {
 299         hdlc_device *hdlc = dev_to_hdlc(dev);
 300         int err;
 301
 302         if (hdlc->proto) {
 303                 err = call_netdevice_notifiers(NETDEV_PRE_TYPE_CHANGE, dev);
 304                 err = notifier_to_errno(err);
 305                 if (err) {
 306                         netdev_err(dev, "Refused to change device type\n");
 307                         return err;
 308                 }
 309
 310                 if (hdlc->proto->detach)
 311                         hdlc->proto->detach(dev);
 312                 module_put(hdlc->proto->module);
 313                 hdlc->proto = NULL;
 314         }
 315         kfree(hdlc->state);
 316         hdlc->state = NULL;
 317         hdlc_setup_dev(dev);
 318
 319         return 0;
 320 }
 321 EXPORT_SYMBOL(detach_hdlc_protocol);
 322
 323 void register_hdlc_protocol(struct hdlc_proto *proto)
 324 {
 325         rtnl_lock();
 326         proto->next = first_proto;
 327         first_proto = proto;
 328         rtnl_unlock();
 329 }
 330 EXPORT_SYMBOL(register_hdlc_protocol);
 331
 332 void unregister_hdlc_protocol(struct hdlc_proto *proto)
 333 {
 334         struct hdlc_proto **p;
 335
 336         rtnl_lock();
 337         p = &first_proto;
 338         while (*p != proto) {
 339                 BUG_ON(!*p);
 340                 p = &((*p)->next);
 341         }
 342         *p = proto->next;
 343         rtnl_unlock();
 344 }
 345 EXPORT_SYMBOL(unregister_hdlc_protocol);
 346
 347 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
 348 MODULE_DESCRIPTION("HDLC support module");
 349 MODULE_LICENSE("GPL v2");
 350
 351 static struct packet_type hdlc_packet_type __read_mostly = {
 352         .type = cpu_to_be16(ETH_P_HDLC),
 353         .func = hdlc_rcv,
 354 };
 355
 356 static struct notifier_block hdlc_notifier = {
 357         .notifier_call = hdlc_device_event,
 358 };
 359
 360 static int __init hdlc_module_init(void)
 361 {
 362         int result;
 363
 364         pr_info("%s\n", version);
 365         result = register_netdevice_notifier(&hdlc_notifier);
 366         if (result)
 367                 return result;
 368         dev_add_pack(&hdlc_packet_type);
 369         return 0;
 370 }
 371
 372 static void __exit hdlc_module_exit(void)
 373 {
 374         dev_remove_pack(&hdlc_packet_type);
 375         unregister_netdevice_notifier(&hdlc_notifier);
 376 }
 377
 378 module_init(hdlc_module_init);
 379 module_exit(hdlc_module_exit);