1 // SPDX-License-Identifier: GPL-2.0-only
6 * o allow users to set the parameters
7 * o sync/async switching ?
9 * Note: This does _not_ implement CCITT X.25 asynchronous framing
10 * recommendations. Its primarily for testing purposes. If you wanted
11 * to do CCITT then in theory all you need is to nick the HDLC async
12 * checksum routines from ppp.c
15 * 2000-10-29 Henner Eisen lapb_data_indication() return status.
18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20 #include <linux/module.h>
22 #include <linux/uaccess.h>
23 #include <linux/bitops.h>
24 #include <linux/string.h>
26 #include <linux/interrupt.h>
28 #include <linux/tty.h>
29 #include <linux/errno.h>
30 #include <linux/netdevice.h>
31 #include <linux/etherdevice.h>
32 #include <linux/skbuff.h>
33 #include <linux/if_arp.h>
34 #include <linux/lapb.h>
35 #include <linux/init.h>
36 #include <linux/rtnetlink.h>
37 #include <linux/slab.h>
38 #include <net/x25device.h>
41 static struct net_device **x25_asy_devs;
42 static int x25_asy_maxdev = SL_NRUNIT;
44 module_param(x25_asy_maxdev, int, 0);
45 MODULE_LICENSE("GPL");
47 static int x25_asy_esc(unsigned char *p, unsigned char *d, int len);
48 static void x25_asy_unesc(struct x25_asy *sl, unsigned char c);
49 static void x25_asy_setup(struct net_device *dev);
51 /* Find a free X.25 channel, and link in this `tty' line. */
52 static struct x25_asy *x25_asy_alloc(void)
54 struct net_device *dev = NULL;
58 if (x25_asy_devs == NULL)
59 return NULL; /* Master array missing ! */
61 for (i = 0; i < x25_asy_maxdev; i++) {
62 dev = x25_asy_devs[i];
68 sl = netdev_priv(dev);
70 if (!test_and_set_bit(SLF_INUSE, &sl->flags))
75 /* Sorry, too many, all slots in use */
76 if (i >= x25_asy_maxdev)
79 /* If no channels are available, allocate one */
82 sprintf(name, "x25asy%d", i);
84 dev = alloc_netdev(sizeof(struct x25_asy), name,
85 NET_NAME_UNKNOWN, x25_asy_setup);
89 /* Initialize channel control data */
90 sl = netdev_priv(dev);
93 /* register device so that it can be ifconfig'ed */
94 if (register_netdev(dev) == 0) {
95 /* (Re-)Set the INUSE bit. Very Important! */
96 set_bit(SLF_INUSE, &sl->flags);
97 x25_asy_devs[i] = dev;
100 pr_warn("%s(): register_netdev() failure\n", __func__);
108 /* Free an X.25 channel. */
109 static void x25_asy_free(struct x25_asy *sl)
111 /* Free all X.25 frame buffers. */
117 if (!test_and_clear_bit(SLF_INUSE, &sl->flags))
118 netdev_err(sl->dev, "x25_asy_free for already free unit\n");
121 static int x25_asy_change_mtu(struct net_device *dev, int newmtu)
123 struct x25_asy *sl = netdev_priv(dev);
124 unsigned char *xbuff, *rbuff;
128 xbuff = kmalloc(len + 4, GFP_ATOMIC);
129 rbuff = kmalloc(len + 4, GFP_ATOMIC);
131 if (xbuff == NULL || rbuff == NULL) {
137 spin_lock_bh(&sl->lock);
138 xbuff = xchg(&sl->xbuff, xbuff);
140 if (sl->xleft <= len) {
141 memcpy(sl->xbuff, sl->xhead, sl->xleft);
144 dev->stats.tx_dropped++;
147 sl->xhead = sl->xbuff;
149 rbuff = xchg(&sl->rbuff, rbuff);
151 if (sl->rcount <= len) {
152 memcpy(sl->rbuff, rbuff, sl->rcount);
155 dev->stats.rx_over_errors++;
156 set_bit(SLF_ERROR, &sl->flags);
163 spin_unlock_bh(&sl->lock);
171 /* Set the "sending" flag. This must be atomic, hence the ASM. */
173 static inline void x25_asy_lock(struct x25_asy *sl)
175 netif_stop_queue(sl->dev);
179 /* Clear the "sending" flag. This must be atomic, hence the ASM. */
181 static inline void x25_asy_unlock(struct x25_asy *sl)
183 netif_wake_queue(sl->dev);
186 /* Send an LAPB frame to the LAPB module to process. */
188 static void x25_asy_bump(struct x25_asy *sl)
190 struct net_device *dev = sl->dev;
196 dev->stats.rx_bytes += count;
198 skb = dev_alloc_skb(count);
200 netdev_warn(sl->dev, "memory squeeze, dropping packet\n");
201 dev->stats.rx_dropped++;
204 skb_put_data(skb, sl->rbuff, count);
205 err = lapb_data_received(sl->dev, skb);
206 if (err != LAPB_OK) {
208 printk(KERN_DEBUG "x25_asy: data received err - %d\n", err);
210 dev->stats.rx_packets++;
214 /* Encapsulate one IP datagram and stuff into a TTY queue. */
215 static void x25_asy_encaps(struct x25_asy *sl, unsigned char *icp, int len)
218 int actual, count, mtu = sl->dev->mtu;
221 /* Sigh, shouldn't occur BUT ... */
223 printk(KERN_DEBUG "%s: truncating oversized transmit packet!\n",
225 sl->dev->stats.tx_dropped++;
231 count = x25_asy_esc(p, sl->xbuff, len);
233 /* Order of next two lines is *very* important.
234 * When we are sending a little amount of data,
235 * the transfer may be completed inside driver.write()
236 * routine, because it's running with interrupts enabled.
237 * In this case we *never* got WRITE_WAKEUP event,
238 * if we did not request it before write operation.
239 * 14 Oct 1994 Dmitry Gorodchanin.
241 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
242 actual = sl->tty->ops->write(sl->tty, sl->xbuff, count);
243 sl->xleft = count - actual;
244 sl->xhead = sl->xbuff + actual;
248 * Called by the driver when there's room for more data. If we have
249 * more packets to send, we send them here.
251 static void x25_asy_write_wakeup(struct tty_struct *tty)
254 struct x25_asy *sl = tty->disc_data;
256 /* First make sure we're connected. */
257 if (!sl || sl->magic != X25_ASY_MAGIC || !netif_running(sl->dev))
260 if (sl->xleft <= 0) {
261 /* Now serial buffer is almost free & we can start
262 * transmission of another packet */
263 sl->dev->stats.tx_packets++;
264 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
269 actual = tty->ops->write(tty, sl->xhead, sl->xleft);
274 static void x25_asy_timeout(struct net_device *dev, unsigned int txqueue)
276 struct x25_asy *sl = netdev_priv(dev);
278 spin_lock(&sl->lock);
279 if (netif_queue_stopped(dev)) {
280 /* May be we must check transmitter timeout here ?
281 * 14 Oct 1994 Dmitry Gorodchanin.
283 netdev_warn(dev, "transmit timed out, %s?\n",
284 (tty_chars_in_buffer(sl->tty) || sl->xleft) ?
285 "bad line quality" : "driver error");
287 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
290 spin_unlock(&sl->lock);
293 /* Encapsulate an IP datagram and kick it into a TTY queue. */
295 static netdev_tx_t x25_asy_xmit(struct sk_buff *skb,
296 struct net_device *dev)
298 struct x25_asy *sl = netdev_priv(dev);
301 if (!netif_running(sl->dev)) {
302 netdev_err(dev, "xmit call when iface is down\n");
307 /* There should be a pseudo header of 1 byte added by upper layers.
308 * Check to make sure it is there before reading it.
315 switch (skb->data[0]) {
318 case X25_IFACE_CONNECT: /* Connection request .. do nothing */
319 err = lapb_connect_request(dev);
321 netdev_err(dev, "lapb_connect_request error: %d\n",
325 case X25_IFACE_DISCONNECT: /* do nothing - hang up ?? */
326 err = lapb_disconnect_request(dev);
328 netdev_err(dev, "lapb_disconnect_request error: %d\n",
335 skb_pull(skb, 1); /* Remove control byte */
337 * If we are busy already- too bad. We ought to be able
338 * to queue things at this point, to allow for a little
339 * frame buffer. Oh well...
340 * -----------------------------------------------------
341 * I hate queues in X.25 driver. May be it's efficient,
342 * but for me latency is more important. ;)
344 * 14 Oct 1994 Dmitry Gorodchanin.
347 err = lapb_data_request(dev, skb);
348 if (err != LAPB_OK) {
349 netdev_err(dev, "lapb_data_request error: %d\n", err);
358 * LAPB interface boilerplate
362 * Called when I frame data arrive. We add a pseudo header for upper
363 * layers and pass it to upper layers.
366 static int x25_asy_data_indication(struct net_device *dev, struct sk_buff *skb)
368 if (skb_cow(skb, 1)) {
373 skb->data[0] = X25_IFACE_DATA;
375 skb->protocol = x25_type_trans(skb, dev);
377 return netif_rx(skb);
381 * Data has emerged from the LAPB protocol machine. We don't handle
382 * busy cases too well. Its tricky to see how to do this nicely -
383 * perhaps lapb should allow us to bounce this ?
386 static void x25_asy_data_transmit(struct net_device *dev, struct sk_buff *skb)
388 struct x25_asy *sl = netdev_priv(dev);
390 spin_lock(&sl->lock);
391 if (netif_queue_stopped(sl->dev) || sl->tty == NULL) {
392 spin_unlock(&sl->lock);
393 netdev_err(dev, "tbusy drop\n");
397 /* We were not busy, so we are now... :-) */
400 dev->stats.tx_bytes += skb->len;
401 x25_asy_encaps(sl, skb->data, skb->len);
404 spin_unlock(&sl->lock);
408 * LAPB connection establish/down information.
411 static void x25_asy_connected(struct net_device *dev, int reason)
413 struct x25_asy *sl = netdev_priv(dev);
417 skb = dev_alloc_skb(1);
419 netdev_err(dev, "out of memory\n");
423 ptr = skb_put(skb, 1);
424 *ptr = X25_IFACE_CONNECT;
426 skb->protocol = x25_type_trans(skb, sl->dev);
430 static void x25_asy_disconnected(struct net_device *dev, int reason)
432 struct x25_asy *sl = netdev_priv(dev);
436 skb = dev_alloc_skb(1);
438 netdev_err(dev, "out of memory\n");
442 ptr = skb_put(skb, 1);
443 *ptr = X25_IFACE_DISCONNECT;
445 skb->protocol = x25_type_trans(skb, sl->dev);
449 static const struct lapb_register_struct x25_asy_callbacks = {
450 .connect_confirmation = x25_asy_connected,
451 .connect_indication = x25_asy_connected,
452 .disconnect_confirmation = x25_asy_disconnected,
453 .disconnect_indication = x25_asy_disconnected,
454 .data_indication = x25_asy_data_indication,
455 .data_transmit = x25_asy_data_transmit,
459 /* Open the low-level part of the X.25 channel. Easy! */
460 static int x25_asy_open(struct net_device *dev)
462 struct x25_asy *sl = netdev_priv(dev);
469 * Allocate the X.25 frame buffers:
471 * rbuff Receive buffer.
472 * xbuff Transmit buffer.
477 sl->rbuff = kmalloc(len + 4, GFP_KERNEL);
478 if (sl->rbuff == NULL)
480 sl->xbuff = kmalloc(len + 4, GFP_KERNEL);
481 if (sl->xbuff == NULL)
487 sl->flags &= (1 << SLF_INUSE); /* Clear ESCAPE & ERROR flags */
502 /* Close the low-level part of the X.25 channel. Easy! */
503 static int x25_asy_close(struct net_device *dev)
505 struct x25_asy *sl = netdev_priv(dev);
507 spin_lock(&sl->lock);
509 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
513 spin_unlock(&sl->lock);
518 * Handle the 'receiver data ready' interrupt.
519 * This function is called by the 'tty_io' module in the kernel when
520 * a block of X.25 data has been received, which can now be decapsulated
521 * and sent on to some IP layer for further processing.
524 static void x25_asy_receive_buf(struct tty_struct *tty,
525 const unsigned char *cp, char *fp, int count)
527 struct x25_asy *sl = tty->disc_data;
529 if (!sl || sl->magic != X25_ASY_MAGIC || !netif_running(sl->dev))
533 /* Read the characters out of the buffer */
536 if (!test_and_set_bit(SLF_ERROR, &sl->flags))
537 sl->dev->stats.rx_errors++;
541 x25_asy_unesc(sl, *cp++);
546 * Open the high-level part of the X.25 channel.
547 * This function is called by the TTY module when the
548 * X.25 line discipline is called for. Because we are
549 * sure the tty line exists, we only have to link it to
550 * a free X.25 channel...
553 static int x25_asy_open_tty(struct tty_struct *tty)
558 if (tty->ops->write == NULL)
561 /* OK. Find a free X.25 channel to use. */
562 sl = x25_asy_alloc();
568 tty->receive_room = 65536;
569 tty_driver_flush_buffer(tty);
570 tty_ldisc_flush(tty);
572 /* Restore default settings */
573 sl->dev->type = ARPHRD_X25;
575 /* Perform the low-level X.25 async init */
576 err = x25_asy_open(sl->dev);
581 /* Done. We have linked the TTY line to a channel. */
587 * Close down an X.25 channel.
588 * This means flushing out any pending queues, and then restoring the
589 * TTY line discipline to what it was before it got hooked to X.25
590 * (which usually is TTY again).
592 static void x25_asy_close_tty(struct tty_struct *tty)
594 struct x25_asy *sl = tty->disc_data;
596 /* First make sure we're connected. */
597 if (!sl || sl->magic != X25_ASY_MAGIC)
601 if (sl->dev->flags & IFF_UP)
605 tty->disc_data = NULL;
610 /************************************************************************
611 * STANDARD X.25 ENCAPSULATION *
612 ************************************************************************/
614 static int x25_asy_esc(unsigned char *s, unsigned char *d, int len)
616 unsigned char *ptr = d;
620 * Send an initial END character to flush out any
621 * data that may have accumulated in the receiver
625 *ptr++ = X25_END; /* Send 10111110 bit seq */
628 * For each byte in the packet, send the appropriate
629 * character sequence, according to the X.25 protocol.
636 *ptr++ = X25_ESCAPE(X25_END);
640 *ptr++ = X25_ESCAPE(X25_ESC);
651 static void x25_asy_unesc(struct x25_asy *sl, unsigned char s)
656 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
659 clear_bit(SLF_ESCAPE, &sl->flags);
663 set_bit(SLF_ESCAPE, &sl->flags);
665 case X25_ESCAPE(X25_ESC):
666 case X25_ESCAPE(X25_END):
667 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
671 if (!test_bit(SLF_ERROR, &sl->flags)) {
672 if (sl->rcount < sl->buffsize) {
673 sl->rbuff[sl->rcount++] = s;
676 sl->dev->stats.rx_over_errors++;
677 set_bit(SLF_ERROR, &sl->flags);
682 /* Perform I/O control on an active X.25 channel. */
683 static int x25_asy_ioctl(struct tty_struct *tty, struct file *file,
684 unsigned int cmd, unsigned long arg)
686 struct x25_asy *sl = tty->disc_data;
688 /* First make sure we're connected. */
689 if (!sl || sl->magic != X25_ASY_MAGIC)
694 if (copy_to_user((void __user *)arg, sl->dev->name,
695 strlen(sl->dev->name) + 1))
701 return tty_mode_ioctl(tty, file, cmd, arg);
705 static int x25_asy_open_dev(struct net_device *dev)
708 struct x25_asy *sl = netdev_priv(dev);
712 err = lapb_register(dev, &x25_asy_callbacks);
716 netif_start_queue(dev);
721 static int x25_asy_close_dev(struct net_device *dev)
725 netif_stop_queue(dev);
727 err = lapb_unregister(dev);
729 pr_err("%s: lapb_unregister error: %d\n",
737 static const struct net_device_ops x25_asy_netdev_ops = {
738 .ndo_open = x25_asy_open_dev,
739 .ndo_stop = x25_asy_close_dev,
740 .ndo_start_xmit = x25_asy_xmit,
741 .ndo_tx_timeout = x25_asy_timeout,
742 .ndo_change_mtu = x25_asy_change_mtu,
745 /* Initialise the X.25 driver. Called by the device init code */
746 static void x25_asy_setup(struct net_device *dev)
748 struct x25_asy *sl = netdev_priv(dev);
750 sl->magic = X25_ASY_MAGIC;
752 spin_lock_init(&sl->lock);
753 set_bit(SLF_INUSE, &sl->flags);
756 * Finish setting up the DEVICE info.
761 dev->max_mtu = 65534;
762 dev->netdev_ops = &x25_asy_netdev_ops;
763 dev->watchdog_timeo = HZ*20;
764 dev->hard_header_len = 0;
766 dev->type = ARPHRD_X25;
767 dev->tx_queue_len = 10;
769 /* When transmitting data:
770 * first this driver removes a pseudo header of 1 byte,
771 * then the lapb module prepends an LAPB header of at most 3 bytes.
773 dev->needed_headroom = 3 - 1;
775 /* New-style flags. */
776 dev->flags = IFF_NOARP;
779 static struct tty_ldisc_ops x25_ldisc = {
780 .owner = THIS_MODULE,
781 .magic = TTY_LDISC_MAGIC,
783 .open = x25_asy_open_tty,
784 .close = x25_asy_close_tty,
785 .ioctl = x25_asy_ioctl,
786 .receive_buf = x25_asy_receive_buf,
787 .write_wakeup = x25_asy_write_wakeup,
790 static int __init init_x25_asy(void)
792 if (x25_asy_maxdev < 4)
793 x25_asy_maxdev = 4; /* Sanity */
795 pr_info("X.25 async: version 0.00 ALPHA (dynamic channels, max=%d)\n",
798 x25_asy_devs = kcalloc(x25_asy_maxdev, sizeof(struct net_device *),
803 return tty_register_ldisc(N_X25, &x25_ldisc);
807 static void __exit exit_x25_asy(void)
809 struct net_device *dev;
812 for (i = 0; i < x25_asy_maxdev; i++) {
813 dev = x25_asy_devs[i];
815 struct x25_asy *sl = netdev_priv(dev);
817 spin_lock_bh(&sl->lock);
821 spin_unlock_bh(&sl->lock);
823 * VSV = if dev->start==0, then device
824 * unregistered while close proc.
826 unregister_netdev(dev);
832 tty_unregister_ldisc(N_X25);
835 module_init(init_x25_asy);
836 module_exit(exit_x25_asy);