Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 836 insertions, 0 deletions

diff --git a/drivers/net/wan/x25_asy.c b/drivers/net/wan/x25_asy.c
new file mode 100644
index 000000000..54b1a5aee
--- /dev/null
+++ b/drivers/net/wan/x25_asy.c
@@ -0,0 +1,836 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *	Things to sort out:
+ *
+ *	o	tbusy handling
+ *	o	allow users to set the parameters
+ *	o	sync/async switching ?
+ *
+ *	Note: This does _not_ implement CCITT X.25 asynchronous framing
+ *	recommendations. Its primarily for testing purposes. If you wanted
+ *	to do CCITT then in theory all you need is to nick the HDLC async
+ *	checksum routines from ppp.c
+ *      Changes:
+ *
+ *	2000-10-29	Henner Eisen	lapb_data_indication() return status.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+
+#include <linux/uaccess.h>
+#include <linux/bitops.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/in.h>
+#include <linux/tty.h>
+#include <linux/errno.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/skbuff.h>
+#include <linux/if_arp.h>
+#include <linux/lapb.h>
+#include <linux/init.h>
+#include <linux/rtnetlink.h>
+#include <linux/slab.h>
+#include <net/x25device.h>
+#include "x25_asy.h"
+
+static struct net_device **x25_asy_devs;
+static int x25_asy_maxdev = SL_NRUNIT;
+
+module_param(x25_asy_maxdev, int, 0);
+MODULE_LICENSE("GPL");
+
+static int x25_asy_esc(unsigned char *p, unsigned char *d, int len);
+static void x25_asy_unesc(struct x25_asy *sl, unsigned char c);
+static void x25_asy_setup(struct net_device *dev);
+
+/* Find a free X.25 channel, and link in this `tty' line. */
+static struct x25_asy *x25_asy_alloc(void)
+{
+	struct net_device *dev = NULL;
+	struct x25_asy *sl;
+	int i;
+
+	if (x25_asy_devs == NULL)
+		return NULL;	/* Master array missing ! */
+
+	for (i = 0; i < x25_asy_maxdev; i++) {
+		dev = x25_asy_devs[i];
+
+		/* Not allocated ? */
+		if (dev == NULL)
+			break;
+
+		sl = netdev_priv(dev);
+		/* Not in use ? */
+		if (!test_and_set_bit(SLF_INUSE, &sl->flags))
+			return sl;
+	}
+
+
+	/* Sorry, too many, all slots in use */
+	if (i >= x25_asy_maxdev)
+		return NULL;
+
+	/* If no channels are available, allocate one */
+	if (!dev) {
+		char name[IFNAMSIZ];
+		sprintf(name, "x25asy%d", i);
+
+		dev = alloc_netdev(sizeof(struct x25_asy), name,
+				   NET_NAME_UNKNOWN, x25_asy_setup);
+		if (!dev)
+			return NULL;
+
+		/* Initialize channel control data */
+		sl = netdev_priv(dev);
+		dev->base_addr    = i;
+
+		/* register device so that it can be ifconfig'ed       */
+		if (register_netdev(dev) == 0) {
+			/* (Re-)Set the INUSE bit.   Very Important! */
+			set_bit(SLF_INUSE, &sl->flags);
+			x25_asy_devs[i] = dev;
+			return sl;
+		} else {
+			pr_warn("%s(): register_netdev() failure\n", __func__);
+			free_netdev(dev);
+		}
+	}
+	return NULL;
+}
+
+
+/* Free an X.25 channel. */
+static void x25_asy_free(struct x25_asy *sl)
+{
+	/* Free all X.25 frame buffers. */
+	kfree(sl->rbuff);
+	sl->rbuff = NULL;
+	kfree(sl->xbuff);
+	sl->xbuff = NULL;
+
+	if (!test_and_clear_bit(SLF_INUSE, &sl->flags))
+		netdev_err(sl->dev, "x25_asy_free for already free unit\n");
+}
+
+static int x25_asy_change_mtu(struct net_device *dev, int newmtu)
+{
+	struct x25_asy *sl = netdev_priv(dev);
+	unsigned char *xbuff, *rbuff;
+	int len;
+
+	len = 2 * newmtu;
+	xbuff = kmalloc(len + 4, GFP_ATOMIC);
+	rbuff = kmalloc(len + 4, GFP_ATOMIC);
+
+	if (xbuff == NULL || rbuff == NULL) {
+		kfree(xbuff);
+		kfree(rbuff);
+		return -ENOMEM;
+	}
+
+	spin_lock_bh(&sl->lock);
+	xbuff    = xchg(&sl->xbuff, xbuff);
+	if (sl->xleft)  {
+		if (sl->xleft <= len)  {
+			memcpy(sl->xbuff, sl->xhead, sl->xleft);
+		} else  {
+			sl->xleft = 0;
+			dev->stats.tx_dropped++;
+		}
+	}
+	sl->xhead = sl->xbuff;
+
+	rbuff	 = xchg(&sl->rbuff, rbuff);
+	if (sl->rcount)  {
+		if (sl->rcount <= len) {
+			memcpy(sl->rbuff, rbuff, sl->rcount);
+		} else  {
+			sl->rcount = 0;
+			dev->stats.rx_over_errors++;
+			set_bit(SLF_ERROR, &sl->flags);
+		}
+	}
+
+	dev->mtu    = newmtu;
+	sl->buffsize = len;
+
+	spin_unlock_bh(&sl->lock);
+
+	kfree(xbuff);
+	kfree(rbuff);
+	return 0;
+}
+
+
+/* Set the "sending" flag.  This must be atomic, hence the ASM. */
+
+static inline void x25_asy_lock(struct x25_asy *sl)
+{
+	netif_stop_queue(sl->dev);
+}
+
+
+/* Clear the "sending" flag.  This must be atomic, hence the ASM. */
+
+static inline void x25_asy_unlock(struct x25_asy *sl)
+{
+	netif_wake_queue(sl->dev);
+}
+
+/* Send an LAPB frame to the LAPB module to process. */
+
+static void x25_asy_bump(struct x25_asy *sl)
+{
+	struct net_device *dev = sl->dev;
+	struct sk_buff *skb;
+	int count;
+	int err;
+
+	count = sl->rcount;
+	dev->stats.rx_bytes += count;
+
+	skb = dev_alloc_skb(count);
+	if (skb == NULL) {
+		netdev_warn(sl->dev, "memory squeeze, dropping packet\n");
+		dev->stats.rx_dropped++;
+		return;
+	}
+	skb_put_data(skb, sl->rbuff, count);
+	err = lapb_data_received(sl->dev, skb);
+	if (err != LAPB_OK) {
+		kfree_skb(skb);
+		printk(KERN_DEBUG "x25_asy: data received err - %d\n", err);
+	} else {
+		dev->stats.rx_packets++;
+	}
+}
+
+/* Encapsulate one IP datagram and stuff into a TTY queue. */
+static void x25_asy_encaps(struct x25_asy *sl, unsigned char *icp, int len)
+{
+	unsigned char *p;
+	int actual, count, mtu = sl->dev->mtu;
+
+	if (len > mtu) {
+		/* Sigh, shouldn't occur BUT ... */
+		len = mtu;
+		printk(KERN_DEBUG "%s: truncating oversized transmit packet!\n",
+					sl->dev->name);
+		sl->dev->stats.tx_dropped++;
+		x25_asy_unlock(sl);
+		return;
+	}
+
+	p = icp;
+	count = x25_asy_esc(p, sl->xbuff, len);
+
+	/* Order of next two lines is *very* important.
+	 * When we are sending a little amount of data,
+	 * the transfer may be completed inside driver.write()
+	 * routine, because it's running with interrupts enabled.
+	 * In this case we *never* got WRITE_WAKEUP event,
+	 * if we did not request it before write operation.
+	 *       14 Oct 1994  Dmitry Gorodchanin.
+	 */
+	set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
+	actual = sl->tty->ops->write(sl->tty, sl->xbuff, count);
+	sl->xleft = count - actual;
+	sl->xhead = sl->xbuff + actual;
+}
+
+/*
+ * Called by the driver when there's room for more data.  If we have
+ * more packets to send, we send them here.
+ */
+static void x25_asy_write_wakeup(struct tty_struct *tty)
+{
+	int actual;
+	struct x25_asy *sl = tty->disc_data;
+
+	/* First make sure we're connected. */
+	if (!sl || sl->magic != X25_ASY_MAGIC || !netif_running(sl->dev))
+		return;
+
+	if (sl->xleft <= 0) {
+		/* Now serial buffer is almost free & we can start
+		 * transmission of another packet */
+		sl->dev->stats.tx_packets++;
+		clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+		x25_asy_unlock(sl);
+		return;
+	}
+
+	actual = tty->ops->write(tty, sl->xhead, sl->xleft);
+	sl->xleft -= actual;
+	sl->xhead += actual;
+}
+
+static void x25_asy_timeout(struct net_device *dev, unsigned int txqueue)
+{
+	struct x25_asy *sl = netdev_priv(dev);
+
+	spin_lock(&sl->lock);
+	if (netif_queue_stopped(dev)) {
+		/* May be we must check transmitter timeout here ?
+		 *      14 Oct 1994 Dmitry Gorodchanin.
+		 */
+		netdev_warn(dev, "transmit timed out, %s?\n",
+			    (tty_chars_in_buffer(sl->tty) || sl->xleft) ?
+			    "bad line quality" : "driver error");
+		sl->xleft = 0;
+		clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
+		x25_asy_unlock(sl);
+	}
+	spin_unlock(&sl->lock);
+}
+
+/* Encapsulate an IP datagram and kick it into a TTY queue. */
+
+static netdev_tx_t x25_asy_xmit(struct sk_buff *skb,
+				      struct net_device *dev)
+{
+	struct x25_asy *sl = netdev_priv(dev);
+	int err;
+
+	if (!netif_running(sl->dev)) {
+		netdev_err(dev, "xmit call when iface is down\n");
+		kfree_skb(skb);
+		return NETDEV_TX_OK;
+	}
+
+	/* There should be a pseudo header of 1 byte added by upper layers.
+	 * Check to make sure it is there before reading it.
+	 */
+	if (skb->len < 1) {
+		kfree_skb(skb);
+		return NETDEV_TX_OK;
+	}
+
+	switch (skb->data[0]) {
+	case X25_IFACE_DATA:
+		break;
+	case X25_IFACE_CONNECT: /* Connection request .. do nothing */
+		err = lapb_connect_request(dev);
+		if (err != LAPB_OK)
+			netdev_err(dev, "lapb_connect_request error: %d\n",
+				   err);
+		kfree_skb(skb);
+		return NETDEV_TX_OK;
+	case X25_IFACE_DISCONNECT: /* do nothing - hang up ?? */
+		err = lapb_disconnect_request(dev);
+		if (err != LAPB_OK)
+			netdev_err(dev, "lapb_disconnect_request error: %d\n",
+				   err);
+		fallthrough;
+	default:
+		kfree_skb(skb);
+		return NETDEV_TX_OK;
+	}
+	skb_pull(skb, 1);	/* Remove control byte */
+	/*
+	 * If we are busy already- too bad.  We ought to be able
+	 * to queue things at this point, to allow for a little
+	 * frame buffer.  Oh well...
+	 * -----------------------------------------------------
+	 * I hate queues in X.25 driver. May be it's efficient,
+	 * but for me latency is more important. ;)
+	 * So, no queues !
+	 *        14 Oct 1994  Dmitry Gorodchanin.
+	 */
+
+	err = lapb_data_request(dev, skb);
+	if (err != LAPB_OK) {
+		netdev_err(dev, "lapb_data_request error: %d\n", err);
+		kfree_skb(skb);
+		return NETDEV_TX_OK;
+	}
+	return NETDEV_TX_OK;
+}
+
+
+/*
+ *	LAPB interface boilerplate
+ */
+
+/*
+ *	Called when I frame data arrive. We add a pseudo header for upper
+ *	layers and pass it to upper layers.
+ */
+
+static int x25_asy_data_indication(struct net_device *dev, struct sk_buff *skb)
+{
+	if (skb_cow(skb, 1)) {
+		kfree_skb(skb);
+		return NET_RX_DROP;
+	}
+	skb_push(skb, 1);
+	skb->data[0] = X25_IFACE_DATA;
+
+	skb->protocol = x25_type_trans(skb, dev);
+
+	return netif_rx(skb);
+}
+
+/*
+ *	Data has emerged from the LAPB protocol machine. We don't handle
+ *	busy cases too well. Its tricky to see how to do this nicely -
+ *	perhaps lapb should allow us to bounce this ?
+ */
+
+static void x25_asy_data_transmit(struct net_device *dev, struct sk_buff *skb)
+{
+	struct x25_asy *sl = netdev_priv(dev);
+
+	spin_lock(&sl->lock);
+	if (netif_queue_stopped(sl->dev) || sl->tty == NULL) {
+		spin_unlock(&sl->lock);
+		netdev_err(dev, "tbusy drop\n");
+		kfree_skb(skb);
+		return;
+	}
+	/* We were not busy, so we are now... :-) */
+	if (skb != NULL) {
+		x25_asy_lock(sl);
+		dev->stats.tx_bytes += skb->len;
+		x25_asy_encaps(sl, skb->data, skb->len);
+		dev_kfree_skb(skb);
+	}
+	spin_unlock(&sl->lock);
+}
+
+/*
+ *	LAPB connection establish/down information.
+ */
+
+static void x25_asy_connected(struct net_device *dev, int reason)
+{
+	struct x25_asy *sl = netdev_priv(dev);
+	struct sk_buff *skb;
+	unsigned char *ptr;
+
+	skb = dev_alloc_skb(1);
+	if (skb == NULL) {
+		netdev_err(dev, "out of memory\n");
+		return;
+	}
+
+	ptr  = skb_put(skb, 1);
+	*ptr = X25_IFACE_CONNECT;
+
+	skb->protocol = x25_type_trans(skb, sl->dev);
+	netif_rx(skb);
+}
+
+static void x25_asy_disconnected(struct net_device *dev, int reason)
+{
+	struct x25_asy *sl = netdev_priv(dev);
+	struct sk_buff *skb;
+	unsigned char *ptr;
+
+	skb = dev_alloc_skb(1);
+	if (skb == NULL) {
+		netdev_err(dev, "out of memory\n");
+		return;
+	}
+
+	ptr  = skb_put(skb, 1);
+	*ptr = X25_IFACE_DISCONNECT;
+
+	skb->protocol = x25_type_trans(skb, sl->dev);
+	netif_rx(skb);
+}
+
+static const struct lapb_register_struct x25_asy_callbacks = {
+	.connect_confirmation = x25_asy_connected,
+	.connect_indication = x25_asy_connected,
+	.disconnect_confirmation = x25_asy_disconnected,
+	.disconnect_indication = x25_asy_disconnected,
+	.data_indication = x25_asy_data_indication,
+	.data_transmit = x25_asy_data_transmit,
+};
+
+
+/* Open the low-level part of the X.25 channel. Easy! */
+static int x25_asy_open(struct net_device *dev)
+{
+	struct x25_asy *sl = netdev_priv(dev);
+	unsigned long len;
+
+	if (sl->tty == NULL)
+		return -ENODEV;
+
+	/*
+	 * Allocate the X.25 frame buffers:
+	 *
+	 * rbuff	Receive buffer.
+	 * xbuff	Transmit buffer.
+	 */
+
+	len = dev->mtu * 2;
+
+	sl->rbuff = kmalloc(len + 4, GFP_KERNEL);
+	if (sl->rbuff == NULL)
+		goto norbuff;
+	sl->xbuff = kmalloc(len + 4, GFP_KERNEL);
+	if (sl->xbuff == NULL)
+		goto noxbuff;
+
+	sl->buffsize = len;
+	sl->rcount   = 0;
+	sl->xleft    = 0;
+	sl->flags   &= (1 << SLF_INUSE);      /* Clear ESCAPE & ERROR flags */
+
+	return 0;
+
+	/* Cleanup */
+	kfree(sl->xbuff);
+	sl->xbuff = NULL;
+noxbuff:
+	kfree(sl->rbuff);
+	sl->rbuff = NULL;
+norbuff:
+	return -ENOMEM;
+}
+
+
+/* Close the low-level part of the X.25 channel. Easy! */
+static int x25_asy_close(struct net_device *dev)
+{
+	struct x25_asy *sl = netdev_priv(dev);
+
+	spin_lock(&sl->lock);
+	if (sl->tty)
+		clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
+
+	sl->rcount = 0;
+	sl->xleft  = 0;
+	spin_unlock(&sl->lock);
+	return 0;
+}
+
+/*
+ * Handle the 'receiver data ready' interrupt.
+ * This function is called by the 'tty_io' module in the kernel when
+ * a block of X.25 data has been received, which can now be decapsulated
+ * and sent on to some IP layer for further processing.
+ */
+
+static void x25_asy_receive_buf(struct tty_struct *tty,
+				const unsigned char *cp, char *fp, int count)
+{
+	struct x25_asy *sl = tty->disc_data;
+
+	if (!sl || sl->magic != X25_ASY_MAGIC || !netif_running(sl->dev))
+		return;
+
+
+	/* Read the characters out of the buffer */
+	while (count--) {
+		if (fp && *fp++) {
+			if (!test_and_set_bit(SLF_ERROR, &sl->flags))
+				sl->dev->stats.rx_errors++;
+			cp++;
+			continue;
+		}
+		x25_asy_unesc(sl, *cp++);
+	}
+}
+
+/*
+ * Open the high-level part of the X.25 channel.
+ * This function is called by the TTY module when the
+ * X.25 line discipline is called for.  Because we are
+ * sure the tty line exists, we only have to link it to
+ * a free X.25 channel...
+ */
+
+static int x25_asy_open_tty(struct tty_struct *tty)
+{
+	struct x25_asy *sl;
+	int err;
+
+	if (tty->ops->write == NULL)
+		return -EOPNOTSUPP;
+
+	/* OK.  Find a free X.25 channel to use. */
+	sl = x25_asy_alloc();
+	if (sl == NULL)
+		return -ENFILE;
+
+	sl->tty = tty;
+	tty->disc_data = sl;
+	tty->receive_room = 65536;
+	tty_driver_flush_buffer(tty);
+	tty_ldisc_flush(tty);
+
+	/* Restore default settings */
+	sl->dev->type = ARPHRD_X25;
+
+	/* Perform the low-level X.25 async init */
+	err = x25_asy_open(sl->dev);
+	if (err) {
+		x25_asy_free(sl);
+		return err;
+	}
+	/* Done.  We have linked the TTY line to a channel. */
+	return 0;
+}
+
+
+/*
+ * Close down an X.25 channel.
+ * This means flushing out any pending queues, and then restoring the
+ * TTY line discipline to what it was before it got hooked to X.25
+ * (which usually is TTY again).
+ */
+static void x25_asy_close_tty(struct tty_struct *tty)
+{
+	struct x25_asy *sl = tty->disc_data;
+
+	/* First make sure we're connected. */
+	if (!sl || sl->magic != X25_ASY_MAGIC)
+		return;
+
+	rtnl_lock();
+	if (sl->dev->flags & IFF_UP)
+		dev_close(sl->dev);
+	rtnl_unlock();
+
+	tty->disc_data = NULL;
+	sl->tty = NULL;
+	x25_asy_free(sl);
+}
+
+ /************************************************************************
+  *			STANDARD X.25 ENCAPSULATION		  	 *
+  ************************************************************************/
+
+static int x25_asy_esc(unsigned char *s, unsigned char *d, int len)
+{
+	unsigned char *ptr = d;
+	unsigned char c;
+
+	/*
+	 * Send an initial END character to flush out any
+	 * data that may have accumulated in the receiver
+	 * due to line noise.
+	 */
+
+	*ptr++ = X25_END;	/* Send 10111110 bit seq */
+
+	/*
+	 * For each byte in the packet, send the appropriate
+	 * character sequence, according to the X.25 protocol.
+	 */
+
+	while (len-- > 0) {
+		switch (c = *s++) {
+		case X25_END:
+			*ptr++ = X25_ESC;
+			*ptr++ = X25_ESCAPE(X25_END);
+			break;
+		case X25_ESC:
+			*ptr++ = X25_ESC;
+			*ptr++ = X25_ESCAPE(X25_ESC);
+			break;
+		default:
+			*ptr++ = c;
+			break;
+		}
+	}
+	*ptr++ = X25_END;
+	return ptr - d;
+}
+
+static void x25_asy_unesc(struct x25_asy *sl, unsigned char s)
+{
+
+	switch (s) {
+	case X25_END:
+		if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
+		    sl->rcount >= 2)
+			x25_asy_bump(sl);
+		clear_bit(SLF_ESCAPE, &sl->flags);
+		sl->rcount = 0;
+		return;
+	case X25_ESC:
+		set_bit(SLF_ESCAPE, &sl->flags);
+		return;
+	case X25_ESCAPE(X25_ESC):
+	case X25_ESCAPE(X25_END):
+		if (test_and_clear_bit(SLF_ESCAPE, &sl->flags))
+			s = X25_UNESCAPE(s);
+		break;
+	}
+	if (!test_bit(SLF_ERROR, &sl->flags)) {
+		if (sl->rcount < sl->buffsize) {
+			sl->rbuff[sl->rcount++] = s;
+			return;
+		}
+		sl->dev->stats.rx_over_errors++;
+		set_bit(SLF_ERROR, &sl->flags);
+	}
+}
+
+
+/* Perform I/O control on an active X.25 channel. */
+static int x25_asy_ioctl(struct tty_struct *tty, struct file *file,
+			 unsigned int cmd,  unsigned long arg)
+{
+	struct x25_asy *sl = tty->disc_data;
+
+	/* First make sure we're connected. */
+	if (!sl || sl->magic != X25_ASY_MAGIC)
+		return -EINVAL;
+
+	switch (cmd) {
+	case SIOCGIFNAME:
+		if (copy_to_user((void __user *)arg, sl->dev->name,
+					strlen(sl->dev->name) + 1))
+			return -EFAULT;
+		return 0;
+	case SIOCSIFHWADDR:
+		return -EINVAL;
+	default:
+		return tty_mode_ioctl(tty, file, cmd, arg);
+	}
+}
+
+static int x25_asy_open_dev(struct net_device *dev)
+{
+	int err;
+	struct x25_asy *sl = netdev_priv(dev);
+	if (sl->tty == NULL)
+		return -ENODEV;
+
+	err = lapb_register(dev, &x25_asy_callbacks);
+	if (err != LAPB_OK)
+		return -ENOMEM;
+
+	netif_start_queue(dev);
+
+	return 0;
+}
+
+static int x25_asy_close_dev(struct net_device *dev)
+{
+	int err;
+
+	netif_stop_queue(dev);
+
+	err = lapb_unregister(dev);
+	if (err != LAPB_OK)
+		pr_err("%s: lapb_unregister error: %d\n",
+		       __func__, err);
+
+	x25_asy_close(dev);
+
+	return 0;
+}
+
+static const struct net_device_ops x25_asy_netdev_ops = {
+	.ndo_open	= x25_asy_open_dev,
+	.ndo_stop	= x25_asy_close_dev,
+	.ndo_start_xmit	= x25_asy_xmit,
+	.ndo_tx_timeout	= x25_asy_timeout,
+	.ndo_change_mtu	= x25_asy_change_mtu,
+};
+
+/* Initialise the X.25 driver.  Called by the device init code */
+static void x25_asy_setup(struct net_device *dev)
+{
+	struct x25_asy *sl = netdev_priv(dev);
+
+	sl->magic  = X25_ASY_MAGIC;
+	sl->dev	   = dev;
+	spin_lock_init(&sl->lock);
+	set_bit(SLF_INUSE, &sl->flags);
+
+	/*
+	 *	Finish setting up the DEVICE info.
+	 */
+
+	dev->mtu		= SL_MTU;
+	dev->min_mtu		= 0;
+	dev->max_mtu		= 65534;
+	dev->netdev_ops		= &x25_asy_netdev_ops;
+	dev->watchdog_timeo	= HZ*20;
+	dev->hard_header_len	= 0;
+	dev->addr_len		= 0;
+	dev->type		= ARPHRD_X25;
+	dev->tx_queue_len	= 10;
+
+	/* When transmitting data:
+	 * first this driver removes a pseudo header of 1 byte,
+	 * then the lapb module prepends an LAPB header of at most 3 bytes.
+	 */
+	dev->needed_headroom	= 3 - 1;
+
+	/* New-style flags. */
+	dev->flags		= IFF_NOARP;
+}
+
+static struct tty_ldisc_ops x25_ldisc = {
+	.owner		= THIS_MODULE,
+	.magic		= TTY_LDISC_MAGIC,
+	.name		= "X.25",
+	.open		= x25_asy_open_tty,
+	.close		= x25_asy_close_tty,
+	.ioctl		= x25_asy_ioctl,
+	.receive_buf	= x25_asy_receive_buf,
+	.write_wakeup	= x25_asy_write_wakeup,
+};
+
+static int __init init_x25_asy(void)
+{
+	if (x25_asy_maxdev < 4)
+		x25_asy_maxdev = 4; /* Sanity */
+
+	pr_info("X.25 async: version 0.00 ALPHA (dynamic channels, max=%d)\n",
+		x25_asy_maxdev);
+
+	x25_asy_devs = kcalloc(x25_asy_maxdev, sizeof(struct net_device *),
+				GFP_KERNEL);
+	if (!x25_asy_devs)
+		return -ENOMEM;
+
+	return tty_register_ldisc(N_X25, &x25_ldisc);
+}
+
+
+static void __exit exit_x25_asy(void)
+{
+	struct net_device *dev;
+	int i;
+
+	for (i = 0; i < x25_asy_maxdev; i++) {
+		dev = x25_asy_devs[i];
+		if (dev) {
+			struct x25_asy *sl = netdev_priv(dev);
+
+			spin_lock_bh(&sl->lock);
+			if (sl->tty)
+				tty_hangup(sl->tty);
+
+			spin_unlock_bh(&sl->lock);
+			/*
+			 * VSV = if dev->start==0, then device
+			 * unregistered while close proc.
+			 */
+			unregister_netdev(dev);
+			free_netdev(dev);
+		}
+	}
+
+	kfree(x25_asy_devs);
+	tty_unregister_ldisc(N_X25);
+}
+
+module_init(init_x25_asy);
+module_exit(exit_x25_asy);