3 files changed, 777 insertions, 0 deletions

diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig
index 080574b0fff0..d5a9db60ade9 100644
--- a/drivers/net/can/Kconfig
+++ b/drivers/net/can/Kconfig
@@ -12,6 +12,27 @@ config CAN_VCAN
           This driver can also be built as a module.  If so, the module
           will be called vcan.
 
+config CAN_SLCAN
+        tristate "Serial / USB serial CAN Adaptors (slcan)"
+        depends on CAN
+        default N
+        ---help---
+          CAN driver for several 'low cost' CAN interfaces that are attached
+          via serial lines or via USB-to-serial adapters using the LAWICEL
+          ASCII protocol. The driver implements the tty linediscipline N_SLCAN.
+
+          As only the sending and receiving of CAN frames is implemented, this
+          driver should work with the (serial/USB) CAN hardware from:
+          www.canusb.com / www.can232.com / www.mictronic.com / www.canhack.de
+
+          Userspace tools to attach the SLCAN line discipline (slcan_attach,
+          slcand) can be found in the can-utils at the SocketCAN SVN, see
+          http://developer.berlios.de/projects/socketcan for details.
+
+          The slcan driver supports up to 10 CAN netdevices by default which
+          can be changed by the 'maxdev=xx' module option. This driver can
+          also be built as a module. If so, the module will be called slcan.
+
 config CAN_DEV
         tristate "Platform CAN drivers with Netlink support"
         depends on CAN
diff --git a/drivers/net/can/Makefile b/drivers/net/can/Makefile
index 90af15a4f106..07ca159ba3f9 100644
--- a/drivers/net/can/Makefile
+++ b/drivers/net/can/Makefile
@@ -3,6 +3,7 @@
 #
 
 obj-$(CONFIG_CAN_VCAN)          += vcan.o
+obj-$(CONFIG_CAN_SLCAN)         += slcan.o
 
 obj-$(CONFIG_CAN_DEV)           += can-dev.o
 can-dev-y                       := dev.o
diff --git a/drivers/net/can/slcan.c b/drivers/net/can/slcan.c
new file mode 100644
index 000000000000..420e95ecc193
--- /dev/null
+++ b/drivers/net/can/slcan.c
@@ -0,0 +1,755 @@
+/*
+ * slcan.c - serial line CAN interface driver (using tty line discipline)
+ *
+ * This file is derived from linux/drivers/net/slip.c
+ *
+ * slip.c Authors  : Laurence Culhane <loz@holmes.demon.co.uk>
+ *                   Fred N. van Kempen <waltje@uwalt.nl.mugnet.org>
+ * slcan.c Author  : Oliver Hartkopp <socketcan@hartkopp.net>
+ *
+ * This program 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 program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307. You can also get it
+ * at http://www.gnu.org/licenses/gpl.html
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ * Send feedback to <socketcan-users@lists.berlios.de>
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+
+#include <asm/system.h>
+#include <linux/uaccess.h>
+#include <linux/bitops.h>
+#include <linux/string.h>
+#include <linux/tty.h>
+#include <linux/errno.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/rtnetlink.h>
+#include <linux/if_arp.h>
+#include <linux/if_ether.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/can.h>
+
+static __initdata const char banner[] =
+        KERN_INFO "slcan: serial line CAN interface driver\n";
+
+MODULE_ALIAS_LDISC(N_SLCAN);
+MODULE_DESCRIPTION("serial line CAN interface");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
+
+#define SLCAN_MAGIC 0x53CA
+
+static int maxdev = 10;         /* MAX number of SLCAN channels;
+                                   This can be overridden with
+                                   insmod slcan.ko maxdev=nnn   */
+module_param(maxdev, int, 0);
+MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
+
+/* maximum rx buffer len: extended CAN frame with timestamp */
+#define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1)
+
+struct slcan {
+        int                     magic;
+
+        /* Various fields. */
+        struct tty_struct       *tty;           /* ptr to TTY structure      */
+        struct net_device       *dev;           /* easy for intr handling    */
+        spinlock_t              lock;
+
+        /* These are pointers to the malloc()ed frame buffers. */
+        unsigned char           rbuff[SLC_MTU]; /* receiver buffer           */
+        int                     rcount;         /* received chars counter    */
+        unsigned char           xbuff[SLC_MTU]; /* transmitter buffer        */
+        unsigned char           *xhead;         /* pointer to next XMIT byte */
+        int                     xleft;          /* bytes left in XMIT queue  */
+
+        unsigned long           flags;          /* Flag values/ mode etc     */
+#define SLF_INUSE               0               /* Channel in use            */
+#define SLF_ERROR               1               /* Parity, etc. error        */
+
+        unsigned char           leased;
+        dev_t                   line;
+        pid_t                   pid;
+};
+
+static struct net_device **slcan_devs;
+
+ /************************************************************************
+  *                     SLCAN ENCAPSULATION FORMAT                       *
+  ************************************************************************/
+
+/*
+ * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended
+ * frame format) a data length code (can_dlc) which can be from 0 to 8
+ * and up to <can_dlc> data bytes as payload.
+ * Additionally a CAN frame may become a remote transmission frame if the
+ * RTR-bit is set. This causes another ECU to send a CAN frame with the
+ * given can_id.
+ *
+ * The SLCAN ASCII representation of these different frame types is:
+ * <type> <id> <dlc> <data>*
+ *
+ * Extended frames (29 bit) are defined by capital characters in the type.
+ * RTR frames are defined as 'r' types - normal frames have 't' type:
+ * t => 11 bit data frame
+ * r => 11 bit RTR frame
+ * T => 29 bit data frame
+ * R => 29 bit RTR frame
+ *
+ * The <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64).
+ * The <dlc> is a one byte ASCII number ('0' - '8')
+ * The <data> section has at much ASCII Hex bytes as defined by the <dlc>
+ *
+ * Examples:
+ *
+ * t1230 : can_id 0x123, can_dlc 0, no data
+ * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33
+ * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55
+ * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request
+ *
+ */
+
+ /************************************************************************
+  *                     STANDARD SLCAN DECAPSULATION                     *
+  ************************************************************************/
+
+static int asc2nibble(char c)
+{
+
+        if ((c >= '0') && (c <= '9'))
+                return c - '0';
+
+        if ((c >= 'A') && (c <= 'F'))
+                return c - 'A' + 10;
+
+        if ((c >= 'a') && (c <= 'f'))
+                return c - 'a' + 10;
+
+        return 16; /* error */
+}
+
+/* Send one completely decapsulated can_frame to the network layer */
+static void slc_bump(struct slcan *sl)
+{
+        struct sk_buff *skb;
+        struct can_frame cf;
+        int i, dlc_pos, tmp;
+        unsigned long ultmp;
+        char cmd = sl->rbuff[0];
+
+        if ((cmd != 't') && (cmd != 'T') && (cmd != 'r') && (cmd != 'R'))
+                return;
+
+        if (cmd & 0x20) /* tiny chars 'r' 't' => standard frame format */
+                dlc_pos = 4; /* dlc position tiiid */
+        else
+                dlc_pos = 9; /* dlc position Tiiiiiiiid */
+
+        if (!((sl->rbuff[dlc_pos] >= '0') && (sl->rbuff[dlc_pos] < '9')))
+                return;
+
+        cf.can_dlc = sl->rbuff[dlc_pos] - '0'; /* get can_dlc from ASCII val */
+
+        sl->rbuff[dlc_pos] = 0; /* terminate can_id string */
+
+        if (strict_strtoul(sl->rbuff+1, 16, &ultmp))
+                return;
+
+        cf.can_id = ultmp;
+
+        if (!(cmd & 0x20)) /* NO tiny chars => extended frame format */
+                cf.can_id |= CAN_EFF_FLAG;
+
+        if ((cmd | 0x20) == 'r') /* RTR frame */
+                cf.can_id |= CAN_RTR_FLAG;
+
+        *(u64 *) (&cf.data) = 0; /* clear payload */
+
+        for (i = 0, dlc_pos++; i < cf.can_dlc; i++) {
+
+                tmp = asc2nibble(sl->rbuff[dlc_pos++]);
+                if (tmp > 0x0F)
+                        return;
+                cf.data[i] = (tmp << 4);
+                tmp = asc2nibble(sl->rbuff[dlc_pos++]);
+                if (tmp > 0x0F)
+                        return;
+                cf.data[i] |= tmp;
+        }
+
+
+        skb = dev_alloc_skb(sizeof(struct can_frame));
+        if (!skb)
+                return;
+
+        skb->dev = sl->dev;
+        skb->protocol = htons(ETH_P_CAN);
+        skb->pkt_type = PACKET_BROADCAST;
+        skb->ip_summed = CHECKSUM_UNNECESSARY;
+        memcpy(skb_put(skb, sizeof(struct can_frame)),
+               &cf, sizeof(struct can_frame));
+        netif_rx(skb);
+
+        sl->dev->stats.rx_packets++;
+        sl->dev->stats.rx_bytes += cf.can_dlc;
+}
+
+/* parse tty input stream */
+static void slcan_unesc(struct slcan *sl, unsigned char s)
+{
+
+        if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */
+                if (!test_and_clear_bit(SLF_ERROR, &sl->flags) &&
+                    (sl->rcount > 4))  {
+                        slc_bump(sl);
+                }
+                sl->rcount = 0;
+        } else {
+                if (!test_bit(SLF_ERROR, &sl->flags))  {
+                        if (sl->rcount < SLC_MTU)  {
+                                sl->rbuff[sl->rcount++] = s;
+                                return;
+                        } else {
+                                sl->dev->stats.rx_over_errors++;
+                                set_bit(SLF_ERROR, &sl->flags);
+                        }
+                }
+        }
+}
+
+ /************************************************************************
+  *                     STANDARD SLCAN ENCAPSULATION                     *
+  ************************************************************************/
+
+/* Encapsulate one can_frame and stuff into a TTY queue. */
+static void slc_encaps(struct slcan *sl, struct can_frame *cf)
+{
+        int actual, idx, i;
+        char cmd;
+
+        if (cf->can_id & CAN_RTR_FLAG)
+                cmd = 'R'; /* becomes 'r' in standard frame format */
+        else
+                cmd = 'T'; /* becomes 't' in standard frame format */
+
+        if (cf->can_id & CAN_EFF_FLAG)
+                sprintf(sl->xbuff, "%c%08X%d", cmd,
+                        cf->can_id & CAN_EFF_MASK, cf->can_dlc);
+        else
+                sprintf(sl->xbuff, "%c%03X%d", cmd | 0x20,
+                        cf->can_id & CAN_SFF_MASK, cf->can_dlc);
+
+        idx = strlen(sl->xbuff);
+
+        for (i = 0; i < cf->can_dlc; i++)
+                sprintf(&sl->xbuff[idx + 2*i], "%02X", cf->data[i]);
+
+        strcat(sl->xbuff, "\r"); /* add terminating character */
+
+        /* Order of next two lines is *very* important.
+         * When we are sending a little amount of data,
+         * the transfer may be completed inside the ops->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, strlen(sl->xbuff));
+        sl->xleft = strlen(sl->xbuff) - actual;
+        sl->xhead = sl->xbuff + actual;
+        sl->dev->stats.tx_bytes += cf->can_dlc;
+}
+
+/*
+ * Called by the driver when there's room for more data.  If we have
+ * more packets to send, we send them here.
+ */
+static void slcan_write_wakeup(struct tty_struct *tty)
+{
+        int actual;
+        struct slcan *sl = (struct slcan *) tty->disc_data;
+
+        /* First make sure we're connected. */
+        if (!sl || sl->magic != SLCAN_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);
+                netif_wake_queue(sl->dev);
+                return;
+        }
+
+        actual = tty->ops->write(tty, sl->xhead, sl->xleft);
+        sl->xleft -= actual;
+        sl->xhead += actual;
+}
+
+/* Send a can_frame to a TTY queue. */
+static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+        struct slcan *sl = netdev_priv(dev);
+
+        if (skb->len != sizeof(struct can_frame))
+                goto out;
+
+        spin_lock(&sl->lock);
+        if (!netif_running(dev))  {
+                spin_unlock(&sl->lock);
+                printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
+                goto out;
+        }
+        if (sl->tty == NULL) {
+                spin_unlock(&sl->lock);
+                goto out;
+        }
+
+        netif_stop_queue(sl->dev);
+        slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */
+        spin_unlock(&sl->lock);
+
+out:
+        kfree_skb(skb);
+        return NETDEV_TX_OK;
+}
+
+
+/******************************************
+ *   Routines looking at netdevice side.
+ ******************************************/
+
+/* Netdevice UP -> DOWN routine */
+static int slc_close(struct net_device *dev)
+{
+        struct slcan *sl = netdev_priv(dev);
+
+        spin_lock_bh(&sl->lock);
+        if (sl->tty) {
+                /* TTY discipline is running. */
+                clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
+        }
+        netif_stop_queue(dev);
+        sl->rcount   = 0;
+        sl->xleft    = 0;
+        spin_unlock_bh(&sl->lock);
+
+        return 0;
+}
+
+/* Netdevice DOWN -> UP routine */
+static int slc_open(struct net_device *dev)
+{
+        struct slcan *sl = netdev_priv(dev);
+
+        if (sl->tty == NULL)
+                return -ENODEV;
+
+        sl->flags &= (1 << SLF_INUSE);
+        netif_start_queue(dev);
+        return 0;
+}
+
+/* Hook the destructor so we can free slcan devs at the right point in time */
+static void slc_free_netdev(struct net_device *dev)
+{
+        int i = dev->base_addr;
+        free_netdev(dev);
+        slcan_devs[i] = NULL;
+}
+
+static const struct net_device_ops slc_netdev_ops = {
+        .ndo_open               = slc_open,
+        .ndo_stop               = slc_close,
+        .ndo_start_xmit         = slc_xmit,
+};
+
+static void slc_setup(struct net_device *dev)
+{
+        dev->netdev_ops         = &slc_netdev_ops;
+        dev->destructor         = slc_free_netdev;
+
+        dev->hard_header_len    = 0;
+        dev->addr_len           = 0;
+        dev->tx_queue_len       = 10;
+
+        dev->mtu                = sizeof(struct can_frame);
+        dev->type               = ARPHRD_CAN;
+
+        /* New-style flags. */
+        dev->flags              = IFF_NOARP;
+        dev->features           = NETIF_F_NO_CSUM;
+}
+
+/******************************************
+  Routines looking at TTY side.
+ ******************************************/
+
+/*
+ * Handle the 'receiver data ready' interrupt.
+ * This function is called by the 'tty_io' module in the kernel when
+ * a block of SLCAN data has been received, which can now be decapsulated
+ * and sent on to some IP layer for further processing. This will not
+ * be re-entered while running but other ldisc functions may be called
+ * in parallel
+ */
+
+static void slcan_receive_buf(struct tty_struct *tty,
+                              const unsigned char *cp, char *fp, int count)
+{
+        struct slcan *sl = (struct slcan *) tty->disc_data;
+
+        if (!sl || sl->magic != SLCAN_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;
+                }
+                slcan_unesc(sl, *cp++);
+        }
+}
+
+/************************************
+ *  slcan_open helper routines.
+ ************************************/
+
+/* Collect hanged up channels */
+static void slc_sync(void)
+{
+        int i;
+        struct net_device *dev;
+        struct slcan      *sl;
+
+        for (i = 0; i < maxdev; i++) {
+                dev = slcan_devs[i];
+                if (dev == NULL)
+                        break;
+
+                sl = netdev_priv(dev);
+                if (sl->tty || sl->leased)
+                        continue;
+                if (dev->flags & IFF_UP)
+                        dev_close(dev);
+        }
+}
+
+/* Find a free SLCAN channel, and link in this `tty' line. */
+static struct slcan *slc_alloc(dev_t line)
+{
+        int i;
+        struct net_device *dev = NULL;
+        struct slcan       *sl;
+
+        if (slcan_devs == NULL)
+                return NULL;    /* Master array missing ! */
+
+        for (i = 0; i < maxdev; i++) {
+                dev = slcan_devs[i];
+                if (dev == NULL)
+                        break;
+
+        }
+
+        /* Sorry, too many, all slots in use */
+        if (i >= maxdev)
+                return NULL;
+
+        if (dev) {
+                sl = netdev_priv(dev);
+                if (test_bit(SLF_INUSE, &sl->flags)) {
+                        unregister_netdevice(dev);
+                        dev = NULL;
+                        slcan_devs[i] = NULL;
+                }
+        }
+
+        if (!dev) {
+                char name[IFNAMSIZ];
+                sprintf(name, "slcan%d", i);
+
+                dev = alloc_netdev(sizeof(*sl), name, slc_setup);
+                if (!dev)
+                        return NULL;
+                dev->base_addr  = i;
+        }
+
+        sl = netdev_priv(dev);
+
+        /* Initialize channel control data */
+        sl->magic = SLCAN_MAGIC;
+        sl->dev = dev;
+        spin_lock_init(&sl->lock);
+        slcan_devs[i] = dev;
+
+        return sl;
+}
+
+/*
+ * Open the high-level part of the SLCAN channel.
+ * This function is called by the TTY module when the
+ * SLCAN line discipline is called for.  Because we are
+ * sure the tty line exists, we only have to link it to
+ * a free SLCAN channel...
+ *
+ * Called in process context serialized from other ldisc calls.
+ */
+
+static int slcan_open(struct tty_struct *tty)
+{
+        struct slcan *sl;
+        int err;
+
+        if (!capable(CAP_NET_ADMIN))
+                return -EPERM;
+
+        if (tty->ops->write == NULL)
+                return -EOPNOTSUPP;
+
+        /* RTnetlink lock is misused here to serialize concurrent
+           opens of slcan channels. There are better ways, but it is
+           the simplest one.
+         */
+        rtnl_lock();
+
+        /* Collect hanged up channels. */
+        slc_sync();
+
+        sl = tty->disc_data;
+
+        err = -EEXIST;
+        /* First make sure we're not already connected. */
+        if (sl && sl->magic == SLCAN_MAGIC)
+                goto err_exit;
+
+        /* OK.  Find a free SLCAN channel to use. */
+        err = -ENFILE;
+        sl = slc_alloc(tty_devnum(tty));
+        if (sl == NULL)
+                goto err_exit;
+
+        sl->tty = tty;
+        tty->disc_data = sl;
+        sl->line = tty_devnum(tty);
+        sl->pid = current->pid;
+
+        if (!test_bit(SLF_INUSE, &sl->flags)) {
+                /* Perform the low-level SLCAN initialization. */
+                sl->rcount   = 0;
+                sl->xleft    = 0;
+
+                set_bit(SLF_INUSE, &sl->flags);
+
+                err = register_netdevice(sl->dev);
+                if (err)
+                        goto err_free_chan;
+        }
+
+        /* Done.  We have linked the TTY line to a channel. */
+        rtnl_unlock();
+        tty->receive_room = 65536;      /* We don't flow control */
+        return sl->dev->base_addr;
+
+err_free_chan:
+        sl->tty = NULL;
+        tty->disc_data = NULL;
+        clear_bit(SLF_INUSE, &sl->flags);
+
+err_exit:
+        rtnl_unlock();
+
+        /* Count references from TTY module */
+        return err;
+}
+
+/*
+ * Close down a SLCAN channel.
+ * This means flushing out any pending queues, and then returning. This
+ * call is serialized against other ldisc functions.
+ *
+ * We also use this method for a hangup event.
+ */
+
+static void slcan_close(struct tty_struct *tty)
+{
+        struct slcan *sl = (struct slcan *) tty->disc_data;
+
+        /* First make sure we're connected. */
+        if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty)
+                return;
+
+        tty->disc_data = NULL;
+        sl->tty = NULL;
+        if (!sl->leased)
+                sl->line = 0;
+
+        /* Flush network side */
+        unregister_netdev(sl->dev);
+        /* This will complete via sl_free_netdev */
+}
+
+static int slcan_hangup(struct tty_struct *tty)
+{
+        slcan_close(tty);
+        return 0;
+}
+
+/* Perform I/O control on an active SLCAN channel. */
+static int slcan_ioctl(struct tty_struct *tty, struct file *file,
+                       unsigned int cmd, unsigned long arg)
+{
+        struct slcan *sl = (struct slcan *) tty->disc_data;
+        unsigned int tmp;
+
+        /* First make sure we're connected. */
+        if (!sl || sl->magic != SLCAN_MAGIC)
+                return -EINVAL;
+
+        switch (cmd) {
+        case SIOCGIFNAME:
+                tmp = strlen(sl->dev->name) + 1;
+                if (copy_to_user((void __user *)arg, sl->dev->name, tmp))
+                        return -EFAULT;
+                return 0;
+
+        case SIOCSIFHWADDR:
+                return -EINVAL;
+
+        default:
+                return tty_mode_ioctl(tty, file, cmd, arg);
+        }
+}
+
+static struct tty_ldisc_ops slc_ldisc = {
+        .owner          = THIS_MODULE,
+        .magic          = TTY_LDISC_MAGIC,
+        .name           = "slcan",
+        .open           = slcan_open,
+        .close          = slcan_close,
+        .hangup         = slcan_hangup,
+        .ioctl          = slcan_ioctl,
+        .receive_buf    = slcan_receive_buf,
+        .write_wakeup   = slcan_write_wakeup,
+};
+
+static int __init slcan_init(void)
+{
+        int status;
+
+        if (maxdev < 4)
+                maxdev = 4; /* Sanity */
+
+        printk(banner);
+        printk(KERN_INFO "slcan: %d dynamic interface channels.\n", maxdev);
+
+        slcan_devs = kzalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL);
+        if (!slcan_devs) {
+                printk(KERN_ERR "slcan: can't allocate slcan device array!\n");
+                return -ENOMEM;
+        }
+
+        /* Fill in our line protocol discipline, and register it */
+        status = tty_register_ldisc(N_SLCAN, &slc_ldisc);
+        if (status)  {
+                printk(KERN_ERR "slcan: can't register line discipline\n");
+                kfree(slcan_devs);
+        }
+        return status;
+}
+
+static void __exit slcan_exit(void)
+{
+        int i;
+        struct net_device *dev;
+        struct slcan *sl;
+        unsigned long timeout = jiffies + HZ;
+        int busy = 0;
+
+        if (slcan_devs == NULL)
+                return;
+
+        /* First of all: check for active disciplines and hangup them.
+         */
+        do {
+                if (busy)
+                        msleep_interruptible(100);
+
+                busy = 0;
+                for (i = 0; i < maxdev; i++) {
+                        dev = slcan_devs[i];
+                        if (!dev)
+                                continue;
+                        sl = netdev_priv(dev);
+                        spin_lock_bh(&sl->lock);
+                        if (sl->tty) {
+                                busy++;
+                                tty_hangup(sl->tty);
+                        }
+                        spin_unlock_bh(&sl->lock);
+                }
+        } while (busy && time_before(jiffies, timeout));
+
+        /* FIXME: hangup is async so we should wait when doing this second
+           phase */
+
+        for (i = 0; i < maxdev; i++) {
+                dev = slcan_devs[i];
+                if (!dev)
+                        continue;
+                slcan_devs[i] = NULL;
+
+                sl = netdev_priv(dev);
+                if (sl->tty) {
+                        printk(KERN_ERR "%s: tty discipline still running\n",
+                               dev->name);
+                        /* Intentionally leak the control block. */
+                        dev->destructor = NULL;
+                }
+
+                unregister_netdev(dev);
+        }
+
+        kfree(slcan_devs);
+        slcan_devs = NULL;
+
+        i = tty_unregister_ldisc(N_SLCAN);
+        if (i)
+                printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i);
+}
+
+module_init(slcan_init);
+module_exit(slcan_exit);