1 files changed, 951 insertions, 0 deletions

diff --git a/drivers/net/hamradio/mkiss.c b/drivers/net/hamradio/mkiss.c
new file mode 100644
index 000000000000..d9ea080aea0f
--- /dev/null
+++ b/drivers/net/hamradio/mkiss.c
@@ -0,0 +1,951 @@
+/*
+ *      MKISS Driver
+ *
+ *      This module:
+ *              This module is free software; you can redistribute it and/or
+ *              modify it under the terms of the GNU General Public License
+ *              as published by the Free Software Foundation; either version
+ *              2 of the License, or (at your option) any later version.
+ *
+ *              This module implements the AX.25 protocol for kernel-based
+ *              devices like TTYs. It interfaces between a raw TTY, and the
+ *              kernel's AX.25 protocol layers, just like slip.c.
+ *              AX.25 needs to be separated from slip.c while slip.c is no
+ *              longer a static kernel device since it is a module.
+ *              This method clears the way to implement other kiss protocols
+ *              like mkiss smack g8bpq ..... so far only mkiss is implemented.
+ *
+ * Hans Alblas <hans@esrac.ele.tue.nl>
+ *
+ *      History
+ *      Jonathan (G4KLX)        Fixed to match Linux networking changes - 2.1.15.
+ *      Matthias (DG2FEF)       Added support for FlexNet CRC (on special request)
+ *                              Fixed bug in ax25_close(): dev_lock_wait() was
+ *                              called twice, causing a deadlock.
+ *      Jeroen (PE1RXQ)         Removed old MKISS_MAGIC stuff and calls to
+ *                              MOD_*_USE_COUNT
+ *                              Remove cli() and fix rtnl lock usage.
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <asm/system.h>
+#include <linux/bitops.h>
+#include <asm/uaccess.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/in.h>
+#include <linux/inet.h>
+#include <linux/tty.h>
+#include <linux/errno.h>
+#include <linux/netdevice.h>
+#include <linux/major.h>
+#include <linux/init.h>
+#include <linux/rtnetlink.h>
+#include <linux/etherdevice.h>
+#include <linux/skbuff.h>
+#include <linux/if_arp.h>
+
+#include <net/ax25.h>
+
+#include "mkiss.h"
+
+#ifdef CONFIG_INET
+#include <linux/ip.h>
+#include <linux/tcp.h>
+#endif
+
+static char banner[] __initdata = KERN_INFO "mkiss: AX.25 Multikiss, Hans Albas PE1AYX\n";
+
+typedef struct ax25_ctrl {
+        struct ax_disp ctrl;    /*                              */
+        struct net_device  dev; /* the device                   */
+} ax25_ctrl_t;
+
+static ax25_ctrl_t **ax25_ctrls;
+
+int ax25_maxdev = AX25_MAXDEV;          /* Can be overridden with insmod! */
+
+static struct tty_ldisc ax_ldisc;
+
+static int ax25_init(struct net_device *);
+static int kiss_esc(unsigned char *, unsigned char *, int);
+static int kiss_esc_crc(unsigned char *, unsigned char *, unsigned short, int);
+static void kiss_unesc(struct ax_disp *, unsigned char);
+
+/*---------------------------------------------------------------------------*/
+
+static const unsigned short Crc_flex_table[] = {
+  0x0f87, 0x1e0e, 0x2c95, 0x3d1c, 0x49a3, 0x582a, 0x6ab1, 0x7b38,
+  0x83cf, 0x9246, 0xa0dd, 0xb154, 0xc5eb, 0xd462, 0xe6f9, 0xf770,
+  0x1f06, 0x0e8f, 0x3c14, 0x2d9d, 0x5922, 0x48ab, 0x7a30, 0x6bb9,
+  0x934e, 0x82c7, 0xb05c, 0xa1d5, 0xd56a, 0xc4e3, 0xf678, 0xe7f1,
+  0x2e85, 0x3f0c, 0x0d97, 0x1c1e, 0x68a1, 0x7928, 0x4bb3, 0x5a3a,
+  0xa2cd, 0xb344, 0x81df, 0x9056, 0xe4e9, 0xf560, 0xc7fb, 0xd672,
+  0x3e04, 0x2f8d, 0x1d16, 0x0c9f, 0x7820, 0x69a9, 0x5b32, 0x4abb,
+  0xb24c, 0xa3c5, 0x915e, 0x80d7, 0xf468, 0xe5e1, 0xd77a, 0xc6f3,
+  0x4d83, 0x5c0a, 0x6e91, 0x7f18, 0x0ba7, 0x1a2e, 0x28b5, 0x393c,
+  0xc1cb, 0xd042, 0xe2d9, 0xf350, 0x87ef, 0x9666, 0xa4fd, 0xb574,
+  0x5d02, 0x4c8b, 0x7e10, 0x6f99, 0x1b26, 0x0aaf, 0x3834, 0x29bd,
+  0xd14a, 0xc0c3, 0xf258, 0xe3d1, 0x976e, 0x86e7, 0xb47c, 0xa5f5,
+  0x6c81, 0x7d08, 0x4f93, 0x5e1a, 0x2aa5, 0x3b2c, 0x09b7, 0x183e,
+  0xe0c9, 0xf140, 0xc3db, 0xd252, 0xa6ed, 0xb764, 0x85ff, 0x9476,
+  0x7c00, 0x6d89, 0x5f12, 0x4e9b, 0x3a24, 0x2bad, 0x1936, 0x08bf,
+  0xf048, 0xe1c1, 0xd35a, 0xc2d3, 0xb66c, 0xa7e5, 0x957e, 0x84f7,
+  0x8b8f, 0x9a06, 0xa89d, 0xb914, 0xcdab, 0xdc22, 0xeeb9, 0xff30,
+  0x07c7, 0x164e, 0x24d5, 0x355c, 0x41e3, 0x506a, 0x62f1, 0x7378,
+  0x9b0e, 0x8a87, 0xb81c, 0xa995, 0xdd2a, 0xcca3, 0xfe38, 0xefb1,
+  0x1746, 0x06cf, 0x3454, 0x25dd, 0x5162, 0x40eb, 0x7270, 0x63f9,
+  0xaa8d, 0xbb04, 0x899f, 0x9816, 0xeca9, 0xfd20, 0xcfbb, 0xde32,
+  0x26c5, 0x374c, 0x05d7, 0x145e, 0x60e1, 0x7168, 0x43f3, 0x527a,
+  0xba0c, 0xab85, 0x991e, 0x8897, 0xfc28, 0xeda1, 0xdf3a, 0xceb3,
+  0x3644, 0x27cd, 0x1556, 0x04df, 0x7060, 0x61e9, 0x5372, 0x42fb,
+  0xc98b, 0xd802, 0xea99, 0xfb10, 0x8faf, 0x9e26, 0xacbd, 0xbd34,
+  0x45c3, 0x544a, 0x66d1, 0x7758, 0x03e7, 0x126e, 0x20f5, 0x317c,
+  0xd90a, 0xc883, 0xfa18, 0xeb91, 0x9f2e, 0x8ea7, 0xbc3c, 0xadb5,
+  0x5542, 0x44cb, 0x7650, 0x67d9, 0x1366, 0x02ef, 0x3074, 0x21fd,
+  0xe889, 0xf900, 0xcb9b, 0xda12, 0xaead, 0xbf24, 0x8dbf, 0x9c36,
+  0x64c1, 0x7548, 0x47d3, 0x565a, 0x22e5, 0x336c, 0x01f7, 0x107e,
+  0xf808, 0xe981, 0xdb1a, 0xca93, 0xbe2c, 0xafa5, 0x9d3e, 0x8cb7,
+  0x7440, 0x65c9, 0x5752, 0x46db, 0x3264, 0x23ed, 0x1176, 0x00ff
+};
+
+/*---------------------------------------------------------------------------*/
+
+static unsigned short calc_crc_flex(unsigned char *cp, int size)
+{
+    unsigned short crc = 0xffff;
+    
+    while (size--)
+        crc = (crc << 8) ^ Crc_flex_table[((crc >> 8) ^ *cp++) & 0xff];
+
+    return crc;
+}
+
+/*---------------------------------------------------------------------------*/
+
+static int check_crc_flex(unsigned char *cp, int size)
+{
+  unsigned short crc = 0xffff;
+
+  if (size < 3)
+      return -1;
+
+  while (size--)
+      crc = (crc << 8) ^ Crc_flex_table[((crc >> 8) ^ *cp++) & 0xff];
+
+  if ((crc & 0xffff) != 0x7070) 
+      return -1;
+
+  return 0;
+}
+
+/*---------------------------------------------------------------------------*/
+
+/* Find a free channel, and link in this `tty' line. */
+static inline struct ax_disp *ax_alloc(void)
+{
+        ax25_ctrl_t *axp=NULL;
+        int i;
+
+        for (i = 0; i < ax25_maxdev; i++) {
+                axp = ax25_ctrls[i];
+
+                /* Not allocated ? */
+                if (axp == NULL)
+                        break;
+
+                /* Not in use ? */
+                if (!test_and_set_bit(AXF_INUSE, &axp->ctrl.flags))
+                        break;
+        }
+
+        /* Sorry, too many, all slots in use */
+        if (i >= ax25_maxdev)
+                return NULL;
+
+        /* If no channels are available, allocate one */
+        if (axp == NULL && (ax25_ctrls[i] = kmalloc(sizeof(ax25_ctrl_t), GFP_KERNEL)) != NULL) {
+                axp = ax25_ctrls[i];
+        }
+        memset(axp, 0, sizeof(ax25_ctrl_t));
+
+        /* Initialize channel control data */
+        set_bit(AXF_INUSE, &axp->ctrl.flags);
+        sprintf(axp->dev.name, "ax%d", i++);
+        axp->ctrl.tty      = NULL;
+        axp->dev.base_addr = i;
+        axp->dev.priv      = (void *)&axp->ctrl;
+        axp->dev.next      = NULL;
+        axp->dev.init      = ax25_init;
+
+        if (axp != NULL) {
+                /*
+                 * register device so that it can be ifconfig'ed
+                 * ax25_init() will be called as a side-effect
+                 * SIDE-EFFECT WARNING: ax25_init() CLEARS axp->ctrl !
+                 */
+                if (register_netdev(&axp->dev) == 0) {
+                        /* (Re-)Set the INUSE bit.   Very Important! */
+                        set_bit(AXF_INUSE, &axp->ctrl.flags);
+                        axp->ctrl.dev = &axp->dev;
+                        axp->dev.priv = (void *) &axp->ctrl;
+
+                        return &axp->ctrl;
+                } else {
+                        clear_bit(AXF_INUSE,&axp->ctrl.flags);
+                        printk(KERN_ERR "mkiss: ax_alloc() - register_netdev() failure.\n");
+                }
+        }
+
+        return NULL;
+}
+
+/* Free an AX25 channel. */
+static inline void ax_free(struct ax_disp *ax)
+{
+        /* Free all AX25 frame buffers. */
+        if (ax->rbuff)
+                kfree(ax->rbuff);
+        ax->rbuff = NULL;
+        if (ax->xbuff)
+                kfree(ax->xbuff);
+        ax->xbuff = NULL;
+        if (!test_and_clear_bit(AXF_INUSE, &ax->flags))
+                printk(KERN_ERR "mkiss: %s: ax_free for already free unit.\n", ax->dev->name);
+}
+
+static void ax_changedmtu(struct ax_disp *ax)
+{
+        struct net_device *dev = ax->dev;
+        unsigned char *xbuff, *rbuff, *oxbuff, *orbuff;
+        int len;
+
+        len = dev->mtu * 2;
+
+        /*
+         * allow for arrival of larger UDP packets, even if we say not to
+         * also fixes a bug in which SunOS sends 512-byte packets even with
+         * an MSS of 128
+         */
+        if (len < 576 * 2)
+                len = 576 * 2;
+
+        xbuff = kmalloc(len + 4, GFP_ATOMIC);
+        rbuff = kmalloc(len + 4, GFP_ATOMIC);
+
+        if (xbuff == NULL || rbuff == NULL)  {
+                printk(KERN_ERR "mkiss: %s: unable to grow ax25 buffers, MTU change cancelled.\n",
+                       ax->dev->name);
+                dev->mtu = ax->mtu;
+                if (xbuff != NULL)
+                        kfree(xbuff);
+                if (rbuff != NULL)
+                        kfree(rbuff);
+                return;
+        }
+
+        spin_lock_bh(&ax->buflock);
+
+        oxbuff    = ax->xbuff;
+        ax->xbuff = xbuff;
+        orbuff    = ax->rbuff;
+        ax->rbuff = rbuff;
+
+        if (ax->xleft) {
+                if (ax->xleft <= len) {
+                        memcpy(ax->xbuff, ax->xhead, ax->xleft);
+                } else  {
+                        ax->xleft = 0;
+                        ax->tx_dropped++;
+                }
+        }
+
+        ax->xhead = ax->xbuff;
+
+        if (ax->rcount) {
+                if (ax->rcount <= len) {
+                        memcpy(ax->rbuff, orbuff, ax->rcount);
+                } else  {
+                        ax->rcount = 0;
+                        ax->rx_over_errors++;
+                        set_bit(AXF_ERROR, &ax->flags);
+                }
+        }
+
+        ax->mtu      = dev->mtu + 73;
+        ax->buffsize = len;
+
+        spin_unlock_bh(&ax->buflock);
+
+        if (oxbuff != NULL)
+                kfree(oxbuff);
+        if (orbuff != NULL)
+                kfree(orbuff);
+}
+
+
+/* Set the "sending" flag.  This must be atomic. */
+static inline void ax_lock(struct ax_disp *ax)
+{
+        netif_stop_queue(ax->dev);
+}
+
+
+/* Clear the "sending" flag.  This must be atomic. */
+static inline void ax_unlock(struct ax_disp *ax)
+{
+        netif_start_queue(ax->dev);
+}
+
+/* Send one completely decapsulated AX.25 packet to the AX.25 layer. */
+static void ax_bump(struct ax_disp *ax)
+{
+        struct sk_buff *skb;
+        int count;
+
+        spin_lock_bh(&ax->buflock);
+        if (ax->rbuff[0] > 0x0f) {
+                if (ax->rbuff[0] & 0x20) {
+                        ax->crcmode = CRC_MODE_FLEX;
+                        if (check_crc_flex(ax->rbuff, ax->rcount) < 0) {
+                                ax->rx_errors++;
+                                return;
+                        }
+                        ax->rcount -= 2;
+                        /* dl9sau bugfix: the trailling two bytes flexnet crc
+                         * will not be passed to the kernel. thus we have
+                         * to correct the kissparm signature, because it
+                         * indicates a crc but there's none
+                         */
+                        *ax->rbuff &= ~0x20;
+                }
+        }
+        spin_unlock_bh(&ax->buflock);
+
+        count = ax->rcount;
+
+        if ((skb = dev_alloc_skb(count)) == NULL) {
+                printk(KERN_ERR "mkiss: %s: memory squeeze, dropping packet.\n", ax->dev->name);
+                ax->rx_dropped++;
+                return;
+        }
+
+        skb->dev      = ax->dev;
+        spin_lock_bh(&ax->buflock);
+        memcpy(skb_put(skb,count), ax->rbuff, count);
+        spin_unlock_bh(&ax->buflock);
+        skb->mac.raw  = skb->data;
+        skb->protocol = htons(ETH_P_AX25);
+        netif_rx(skb);
+        ax->dev->last_rx = jiffies;
+        ax->rx_packets++;
+        ax->rx_bytes+=count;
+}
+
+/* Encapsulate one AX.25 packet and stuff into a TTY queue. */
+static void ax_encaps(struct ax_disp *ax, unsigned char *icp, int len)
+{
+        unsigned char *p;
+        int actual, count;
+
+        if (ax->mtu != ax->dev->mtu + 73)       /* Someone has been ifconfigging */
+                ax_changedmtu(ax);
+
+        if (len > ax->mtu) {            /* Sigh, shouldn't occur BUT ... */
+                len = ax->mtu;
+                printk(KERN_ERR "mkiss: %s: truncating oversized transmit packet!\n", ax->dev->name);
+                ax->tx_dropped++;
+                ax_unlock(ax);
+                return;
+        }
+
+        p = icp;
+
+        spin_lock_bh(&ax->buflock);
+        switch (ax->crcmode) {
+                 unsigned short crc;
+
+        case CRC_MODE_FLEX:
+                 *p |= 0x20;
+                 crc = calc_crc_flex(p, len);
+                 count = kiss_esc_crc(p, (unsigned char *)ax->xbuff, crc, len+2);
+                 break;
+
+        default:
+                 count = kiss_esc(p, (unsigned char *)ax->xbuff, len);
+                 break;
+        }
+        
+        ax->tty->flags |= (1 << TTY_DO_WRITE_WAKEUP);
+        actual = ax->tty->driver->write(ax->tty, ax->xbuff, count);
+        ax->tx_packets++;
+        ax->tx_bytes+=actual;
+        ax->dev->trans_start = jiffies;
+        ax->xleft = count - actual;
+        ax->xhead = ax->xbuff + actual;
+
+        spin_unlock_bh(&ax->buflock);
+}
+
+/*
+ * Called by the driver when there's room for more data.  If we have
+ * more packets to send, we send them here.
+ */
+static void ax25_write_wakeup(struct tty_struct *tty)
+{
+        int actual;
+        struct ax_disp *ax = (struct ax_disp *) tty->disc_data;
+
+        /* First make sure we're connected. */
+        if (ax == NULL || ax->magic != AX25_MAGIC || !netif_running(ax->dev))
+                return;
+        if (ax->xleft <= 0)  {
+                /* Now serial buffer is almost free & we can start
+                 * transmission of another packet
+                 */
+                tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
+
+                netif_wake_queue(ax->dev);
+                return;
+        }
+
+        actual = tty->driver->write(tty, ax->xhead, ax->xleft);
+        ax->xleft -= actual;
+        ax->xhead += actual;
+}
+
+/* Encapsulate an AX.25 packet and kick it into a TTY queue. */
+static int ax_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+        struct ax_disp *ax = netdev_priv(dev);
+
+        if (!netif_running(dev))  {
+                printk(KERN_ERR "mkiss: %s: xmit call when iface is down\n", dev->name);
+                return 1;
+        }
+
+        if (netif_queue_stopped(dev)) {
+                /*
+                 * May be we must check transmitter timeout here ?
+                 *      14 Oct 1994 Dmitry Gorodchanin.
+                 */
+                if (jiffies - dev->trans_start  < 20 * HZ) {
+                        /* 20 sec timeout not reached */
+                        return 1;
+                }
+
+                printk(KERN_ERR "mkiss: %s: transmit timed out, %s?\n", dev->name,
+                       (ax->tty->driver->chars_in_buffer(ax->tty) || ax->xleft) ?
+                       "bad line quality" : "driver error");
+
+                ax->xleft = 0;
+                ax->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
+                ax_unlock(ax);
+        }
+
+        /* We were not busy, so we are now... :-) */
+        if (skb != NULL) {
+                ax_lock(ax);
+                ax_encaps(ax, skb->data, skb->len);
+                kfree_skb(skb);
+        }
+
+        return 0;
+}
+
+#if defined(CONFIG_AX25) || defined(CONFIG_AX25_MODULE)
+
+/* Return the frame type ID */
+static int ax_header(struct sk_buff *skb, struct net_device *dev, unsigned short type,
+          void *daddr, void *saddr, unsigned len)
+{
+#ifdef CONFIG_INET
+        if (type != htons(ETH_P_AX25))
+                return ax25_encapsulate(skb, dev, type, daddr, saddr, len);
+#endif
+        return 0;
+}
+
+
+static int ax_rebuild_header(struct sk_buff *skb)
+{
+#ifdef CONFIG_INET
+        return ax25_rebuild_header(skb);
+#else
+        return 0;
+#endif
+}
+
+#endif  /* CONFIG_{AX25,AX25_MODULE} */
+
+/* Open the low-level part of the AX25 channel. Easy! */
+static int ax_open(struct net_device *dev)
+{
+        struct ax_disp *ax = netdev_priv(dev);
+        unsigned long len;
+
+        if (ax->tty == NULL)
+                return -ENODEV;
+
+        /*
+         * Allocate the frame buffers:
+         *
+         * rbuff        Receive buffer.
+         * xbuff        Transmit buffer.
+         */
+        len = dev->mtu * 2;
+
+        /*
+         * allow for arrival of larger UDP packets, even if we say not to
+         * also fixes a bug in which SunOS sends 512-byte packets even with
+         * an MSS of 128
+         */
+        if (len < 576 * 2)
+                len = 576 * 2;
+
+        if ((ax->rbuff = kmalloc(len + 4, GFP_KERNEL)) == NULL)
+                goto norbuff;
+
+        if ((ax->xbuff = kmalloc(len + 4, GFP_KERNEL)) == NULL)
+                goto noxbuff;
+
+        ax->mtu      = dev->mtu + 73;
+        ax->buffsize = len;
+        ax->rcount   = 0;
+        ax->xleft    = 0;
+
+        ax->flags   &= (1 << AXF_INUSE);      /* Clear ESCAPE & ERROR flags */
+
+        spin_lock_init(&ax->buflock);
+
+        netif_start_queue(dev);
+        return 0;
+
+noxbuff:
+        kfree(ax->rbuff);
+
+norbuff:
+        return -ENOMEM;
+}
+
+
+/* Close the low-level part of the AX25 channel. Easy! */
+static int ax_close(struct net_device *dev)
+{
+        struct ax_disp *ax = netdev_priv(dev);
+
+        if (ax->tty == NULL)
+                return -EBUSY;
+
+        ax->tty->flags &= ~(1 << TTY_DO_WRITE_WAKEUP);
+
+        netif_stop_queue(dev);
+
+        return 0;
+}
+
+static int ax25_receive_room(struct tty_struct *tty)
+{
+        return 65536;  /* We can handle an infinite amount of data. :-) */
+}
+
+/*
+ * Handle the 'receiver data ready' interrupt.
+ * This function is called by the 'tty_io' module in the kernel when
+ * a block of data has been received, which can now be decapsulated
+ * and sent on to the AX.25 layer for further processing.
+ */
+static void ax25_receive_buf(struct tty_struct *tty, const unsigned char *cp, char *fp, int count)
+{
+        struct ax_disp *ax = (struct ax_disp *) tty->disc_data;
+
+        if (ax == NULL || ax->magic != AX25_MAGIC || !netif_running(ax->dev))
+                return;
+
+        /*
+         * Argh! mtu change time! - costs us the packet part received
+         * at the change
+         */
+        if (ax->mtu != ax->dev->mtu + 73)
+                ax_changedmtu(ax);
+
+        /* Read the characters out of the buffer */
+        while (count--) {
+                if (fp != NULL && *fp++) {
+                        if (!test_and_set_bit(AXF_ERROR, &ax->flags))
+                                ax->rx_errors++;
+                        cp++;
+                        continue;
+                }
+
+                kiss_unesc(ax, *cp++);
+        }
+}
+
+static int ax25_open(struct tty_struct *tty)
+{
+        struct ax_disp *ax = (struct ax_disp *) tty->disc_data;
+        int err;
+
+        /* First make sure we're not already connected. */
+        if (ax && ax->magic == AX25_MAGIC)
+                return -EEXIST;
+
+        /* OK.  Find a free AX25 channel to use. */
+        if ((ax = ax_alloc()) == NULL)
+                return -ENFILE;
+
+        ax->tty = tty;
+        tty->disc_data = ax;
+
+        if (tty->driver->flush_buffer)
+                tty->driver->flush_buffer(tty);
+
+        /* Restore default settings */
+        ax->dev->type = ARPHRD_AX25;
+
+        /* Perform the low-level AX25 initialization. */
+        if ((err = ax_open(ax->dev)))
+                return err;
+
+        /* Done.  We have linked the TTY line to a channel. */
+        return ax->dev->base_addr;
+}
+
+static void ax25_close(struct tty_struct *tty)
+{
+        struct ax_disp *ax = (struct ax_disp *) tty->disc_data;
+
+        /* First make sure we're connected. */
+        if (ax == NULL || ax->magic != AX25_MAGIC)
+                return;
+
+        unregister_netdev(ax->dev);
+
+        tty->disc_data = NULL;
+        ax->tty        = NULL;
+
+        ax_free(ax);
+}
+
+
+static struct net_device_stats *ax_get_stats(struct net_device *dev)
+{
+        static struct net_device_stats stats;
+        struct ax_disp *ax = netdev_priv(dev);
+
+        memset(&stats, 0, sizeof(struct net_device_stats));
+
+        stats.rx_packets     = ax->rx_packets;
+        stats.tx_packets     = ax->tx_packets;
+        stats.rx_bytes       = ax->rx_bytes;
+        stats.tx_bytes       = ax->tx_bytes;
+        stats.rx_dropped     = ax->rx_dropped;
+        stats.tx_dropped     = ax->tx_dropped;
+        stats.tx_errors      = ax->tx_errors;
+        stats.rx_errors      = ax->rx_errors;
+        stats.rx_over_errors = ax->rx_over_errors;
+
+        return &stats;
+}
+
+
+/************************************************************************
+ *                         STANDARD ENCAPSULATION                        *
+ ************************************************************************/
+
+static int kiss_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++ = END;
+
+        while (len-- > 0) {
+                switch (c = *s++) {
+                        case END:
+                                *ptr++ = ESC;
+                                *ptr++ = ESC_END;
+                                break;
+                        case ESC:
+                                *ptr++ = ESC;
+                                *ptr++ = ESC_ESC;
+                                break;
+                        default:
+                                *ptr++ = c;
+                                break;
+                }
+        }
+
+        *ptr++ = END;
+
+        return ptr - d;
+}
+
+/*
+ * MW:
+ * OK its ugly, but tell me a better solution without copying the
+ * packet to a temporary buffer :-)
+ */
+static int kiss_esc_crc(unsigned char *s, unsigned char *d, unsigned short crc, int len)
+{
+        unsigned char *ptr = d;
+        unsigned char c=0;
+
+        *ptr++ = END;
+        while (len > 0) {
+                if (len > 2) 
+                        c = *s++;
+                else if (len > 1)
+                        c = crc >> 8;
+                else if (len > 0)
+                        c = crc & 0xff;
+
+                len--;
+
+                switch (c) {
+                        case END:
+                                *ptr++ = ESC;
+                                *ptr++ = ESC_END;
+                                break;
+                        case ESC:
+                                *ptr++ = ESC;
+                                *ptr++ = ESC_ESC;
+                                break;
+                        default:
+                                *ptr++ = c;
+                                break;
+                }
+        }
+        *ptr++ = END;
+        return ptr - d;         
+}
+
+static void kiss_unesc(struct ax_disp *ax, unsigned char s)
+{
+        switch (s) {
+                case END:
+                        /* drop keeptest bit = VSV */
+                        if (test_bit(AXF_KEEPTEST, &ax->flags))
+                                clear_bit(AXF_KEEPTEST, &ax->flags);
+
+                        if (!test_and_clear_bit(AXF_ERROR, &ax->flags) && (ax->rcount > 2))
+                                ax_bump(ax);
+
+                        clear_bit(AXF_ESCAPE, &ax->flags);
+                        ax->rcount = 0;
+                        return;
+
+                case ESC:
+                        set_bit(AXF_ESCAPE, &ax->flags);
+                        return;
+                case ESC_ESC:
+                        if (test_and_clear_bit(AXF_ESCAPE, &ax->flags))
+                                s = ESC;
+                        break;
+                case ESC_END:
+                        if (test_and_clear_bit(AXF_ESCAPE, &ax->flags))
+                                s = END;
+                        break;
+        }
+
+        spin_lock_bh(&ax->buflock);
+        if (!test_bit(AXF_ERROR, &ax->flags)) {
+                if (ax->rcount < ax->buffsize) {
+                        ax->rbuff[ax->rcount++] = s;
+                        spin_unlock_bh(&ax->buflock);
+                        return;
+                }
+
+                ax->rx_over_errors++;
+                set_bit(AXF_ERROR, &ax->flags);
+        }
+        spin_unlock_bh(&ax->buflock);
+}
+
+
+static int ax_set_mac_address(struct net_device *dev, void __user *addr)
+{
+        if (copy_from_user(dev->dev_addr, addr, AX25_ADDR_LEN))
+                return -EFAULT;
+        return 0;
+}
+
+static int ax_set_dev_mac_address(struct net_device *dev, void *addr)
+{
+        struct sockaddr *sa = addr;
+
+        memcpy(dev->dev_addr, sa->sa_data, AX25_ADDR_LEN);
+
+        return 0;
+}
+
+
+/* Perform I/O control on an active ax25 channel. */
+static int ax25_disp_ioctl(struct tty_struct *tty, void *file, int cmd, void __user *arg)
+{
+        struct ax_disp *ax = (struct ax_disp *) tty->disc_data;
+        unsigned int tmp;
+
+        /* First make sure we're connected. */
+        if (ax == NULL || ax->magic != AX25_MAGIC)
+                return -EINVAL;
+
+        switch (cmd) {
+                case SIOCGIFNAME:
+                        if (copy_to_user(arg, ax->dev->name, strlen(ax->dev->name) + 1))
+                                return -EFAULT;
+                        return 0;
+
+                case SIOCGIFENCAP:
+                        return put_user(4, (int __user *)arg);
+
+                case SIOCSIFENCAP:
+                        if (get_user(tmp, (int __user *)arg))
+                                return -EFAULT;
+                        ax->mode = tmp;
+                        ax->dev->addr_len        = AX25_ADDR_LEN;         /* sizeof an AX.25 addr */
+                        ax->dev->hard_header_len = AX25_KISS_HEADER_LEN + AX25_MAX_HEADER_LEN + 3;
+                        ax->dev->type            = ARPHRD_AX25;
+                        return 0;
+
+                 case SIOCSIFHWADDR:
+                        return ax_set_mac_address(ax->dev, arg);
+
+                default:
+                        return -ENOIOCTLCMD;
+        }
+}
+
+static int ax_open_dev(struct net_device *dev)
+{
+        struct ax_disp *ax = netdev_priv(dev);
+
+        if (ax->tty == NULL)
+                return -ENODEV;
+
+        return 0;
+}
+
+
+/* Initialize the driver.  Called by network startup. */
+static int ax25_init(struct net_device *dev)
+{
+        struct ax_disp *ax = netdev_priv(dev);
+
+        static char ax25_bcast[AX25_ADDR_LEN] =
+                {'Q'<<1,'S'<<1,'T'<<1,' '<<1,' '<<1,' '<<1,'0'<<1};
+        static char ax25_test[AX25_ADDR_LEN] =
+                {'L'<<1,'I'<<1,'N'<<1,'U'<<1,'X'<<1,' '<<1,'1'<<1};
+
+        if (ax == NULL)         /* Allocation failed ?? */
+                return -ENODEV;
+
+        /* Set up the "AX25 Control Block". (And clear statistics) */
+        memset(ax, 0, sizeof (struct ax_disp));
+        ax->magic  = AX25_MAGIC;
+        ax->dev    = dev;
+
+        /* Finish setting up the DEVICE info. */
+        dev->mtu             = AX_MTU;
+        dev->hard_start_xmit = ax_xmit;
+        dev->open            = ax_open_dev;
+        dev->stop            = ax_close;
+        dev->get_stats       = ax_get_stats;
+        dev->set_mac_address = ax_set_dev_mac_address;
+        dev->hard_header_len = 0;
+        dev->addr_len        = 0;
+        dev->type            = ARPHRD_AX25;
+        dev->tx_queue_len    = 10;
+        dev->hard_header     = ax_header;
+        dev->rebuild_header  = ax_rebuild_header;
+
+        memcpy(dev->broadcast, ax25_bcast, AX25_ADDR_LEN);
+        memcpy(dev->dev_addr,  ax25_test,  AX25_ADDR_LEN);
+
+        /* New-style flags. */
+        dev->flags      = IFF_BROADCAST | IFF_MULTICAST;
+
+        return 0;
+}
+
+
+/* ******************************************************************** */
+/* *                    Init MKISS driver                             * */
+/* ******************************************************************** */
+
+static int __init mkiss_init_driver(void)
+{
+        int status;
+
+        printk(banner);
+
+        if (ax25_maxdev < 4)
+          ax25_maxdev = 4; /* Sanity */
+
+        if ((ax25_ctrls = kmalloc(sizeof(void *) * ax25_maxdev, GFP_KERNEL)) == NULL) {
+                printk(KERN_ERR "mkiss: Can't allocate ax25_ctrls[] array!\n");
+                return -ENOMEM;
+        }
+
+        /* Clear the pointer array, we allocate devices when we need them */
+        memset(ax25_ctrls, 0, sizeof(void*) * ax25_maxdev); /* Pointers */
+
+        /* Fill in our line protocol discipline, and register it */
+        ax_ldisc.magic          = TTY_LDISC_MAGIC;
+        ax_ldisc.name           = "mkiss";
+        ax_ldisc.open           = ax25_open;
+        ax_ldisc.close          = ax25_close;
+        ax_ldisc.ioctl          = (int (*)(struct tty_struct *, struct file *,
+                                        unsigned int, unsigned long))ax25_disp_ioctl;
+        ax_ldisc.receive_buf    = ax25_receive_buf;
+        ax_ldisc.receive_room   = ax25_receive_room;
+        ax_ldisc.write_wakeup   = ax25_write_wakeup;
+
+        if ((status = tty_register_ldisc(N_AX25, &ax_ldisc)) != 0) {
+                printk(KERN_ERR "mkiss: can't register line discipline (err = %d)\n", status);
+                kfree(ax25_ctrls);
+        }
+        return status;
+}
+
+static void __exit mkiss_exit_driver(void)
+{
+        int i;
+
+        for (i = 0; i < ax25_maxdev; i++) {
+                if (ax25_ctrls[i]) {
+                        /*
+                        * VSV = if dev->start==0, then device
+                        * unregistered while close proc.
+                        */
+                        if (netif_running(&ax25_ctrls[i]->dev))
+                                unregister_netdev(&ax25_ctrls[i]->dev);
+                        kfree(ax25_ctrls[i]);
+                }
+        }
+
+        kfree(ax25_ctrls);
+        ax25_ctrls = NULL;
+
+        if ((i = tty_register_ldisc(N_AX25, NULL)))
+                printk(KERN_ERR "mkiss: can't unregister line discipline (err = %d)\n", i);
+}
+
+MODULE_AUTHOR("Hans Albas PE1AYX <hans@esrac.ele.tue.nl>");
+MODULE_DESCRIPTION("KISS driver for AX.25 over TTYs");
+MODULE_PARM(ax25_maxdev, "i");
+MODULE_PARM_DESC(ax25_maxdev, "number of MKISS devices");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_LDISC(N_AX25);
+module_init(mkiss_init_driver);
+module_exit(mkiss_exit_driver);
+