[PATCH] isdn4linux: Siemens Gigaset drivers - tty interface

And: Tilman Schmidt <tilman@imap.cc>

This patch adds the tty interface to the gigaset module.  The tty interface
provides direct access to the AT command set of the Gigaset devices.

Signed-off-by: Hansjoerg Lipp <hjlipp@web.de>
Signed-off-by: Tilman Schmidt <tilman@imap.cc>
Cc: Karsten Keil <kkeil@suse.de>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 718 insertions, 0 deletions

diff --git a/drivers/isdn/gigaset/interface.c b/drivers/isdn/gigaset/interface.c
new file mode 100644
index 0000000..3a81d9c
--- /dev/null
+++ b/drivers/isdn/gigaset/interface.c
@@ -0,0 +1,718 @@
+/*
+ * interface to user space for the gigaset driver
+ *
+ * Copyright (c) 2004 by Hansjoerg Lipp <hjlipp@web.de>
+ *
+ * =====================================================================
+ *    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.
+ * =====================================================================
+ * Version: $Id: interface.c,v 1.14.4.15 2006/02/04 18:28:16 hjlipp Exp $
+ * =====================================================================
+ */
+
+#include "gigaset.h"
+#include <linux/gigaset_dev.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+
+/*** our ioctls ***/
+
+static int if_lock(struct cardstate *cs, int *arg)
+{
+	int cmd = *arg;
+
+	dbg(DEBUG_IF, "%u: if_lock (%d)", cs->minor_index, cmd);
+
+	if (cmd > 1)
+		return -EINVAL;
+
+	if (cmd < 0) {
+		*arg = atomic_read(&cs->mstate) == MS_LOCKED; //FIXME remove?
+		return 0;
+	}
+
+	if (!cmd && atomic_read(&cs->mstate) == MS_LOCKED
+	    && atomic_read(&cs->connected)) {
+		cs->ops->set_modem_ctrl(cs, 0, TIOCM_DTR|TIOCM_RTS);
+		cs->ops->baud_rate(cs, B115200);
+		cs->ops->set_line_ctrl(cs, CS8);
+		cs->control_state = TIOCM_DTR|TIOCM_RTS;
+	}
+
+	cs->waiting = 1;
+	if (!gigaset_add_event(cs, &cs->at_state, EV_IF_LOCK,
+		               NULL, cmd, NULL)) {
+		cs->waiting = 0;
+		return -ENOMEM;
+	}
+
+	dbg(DEBUG_CMD, "scheduling IF_LOCK");
+	gigaset_schedule_event(cs);
+
+	wait_event(cs->waitqueue, !cs->waiting);
+
+	if (cs->cmd_result >= 0) {
+		*arg = cs->cmd_result;
+		return 0;
+	}
+
+	return cs->cmd_result;
+}
+
+static int if_version(struct cardstate *cs, unsigned arg[4])
+{
+	static const unsigned version[4] = GIG_VERSION;
+	static const unsigned compat[4] = GIG_COMPAT;
+	unsigned cmd = arg[0];
+
+	dbg(DEBUG_IF, "%u: if_version (%d)", cs->minor_index, cmd);
+
+	switch (cmd) {
+	case GIGVER_DRIVER:
+		memcpy(arg, version, sizeof version);
+		return 0;
+	case GIGVER_COMPAT:
+		memcpy(arg, compat, sizeof compat);
+		return 0;
+	case GIGVER_FWBASE:
+		cs->waiting = 1;
+		if (!gigaset_add_event(cs, &cs->at_state, EV_IF_VER,
+			               NULL, 0, arg)) {
+			cs->waiting = 0;
+			return -ENOMEM;
+		}
+
+		dbg(DEBUG_CMD, "scheduling IF_VER");
+		gigaset_schedule_event(cs);
+
+		wait_event(cs->waitqueue, !cs->waiting);
+
+		if (cs->cmd_result >= 0)
+			return 0;
+
+		return cs->cmd_result;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int if_config(struct cardstate *cs, int *arg)
+{
+	dbg(DEBUG_IF, "%u: if_config (%d)", cs->minor_index, *arg);
+
+	if (*arg != 1)
+		return -EINVAL;
+
+	if (atomic_read(&cs->mstate) != MS_LOCKED)
+		return -EBUSY;
+
+	*arg = 0;
+	return gigaset_enterconfigmode(cs);
+}
+
+/*** the terminal driver ***/
+/* stolen from usbserial and some other tty drivers */
+
+static int  if_open(struct tty_struct *tty, struct file *filp);
+static void if_close(struct tty_struct *tty, struct file *filp);
+static int  if_ioctl(struct tty_struct *tty, struct file *file,
+                     unsigned int cmd, unsigned long arg);
+static int  if_write_room(struct tty_struct *tty);
+static int  if_chars_in_buffer(struct tty_struct *tty);
+static void if_throttle(struct tty_struct *tty);
+static void if_unthrottle(struct tty_struct *tty);
+static void if_set_termios(struct tty_struct *tty, struct termios *old);
+static int  if_tiocmget(struct tty_struct *tty, struct file *file);
+static int  if_tiocmset(struct tty_struct *tty, struct file *file,
+                        unsigned int set, unsigned int clear);
+static int  if_write(struct tty_struct *tty,
+                     const unsigned char *buf, int count);
+
+static struct tty_operations if_ops = {
+	.open =			if_open,
+	.close =		if_close,
+	.ioctl =		if_ioctl,
+	.write =		if_write,
+	.write_room =		if_write_room,
+	.chars_in_buffer =	if_chars_in_buffer,
+	.set_termios =		if_set_termios,
+	.throttle =		if_throttle,
+	.unthrottle =		if_unthrottle,
+#if 0
+	.break_ctl =		serial_break,
+#endif
+	.tiocmget =		if_tiocmget,
+	.tiocmset =		if_tiocmset,
+};
+
+static int if_open(struct tty_struct *tty, struct file *filp)
+{
+	struct cardstate *cs;
+	unsigned long flags;
+
+	dbg(DEBUG_IF, "%d+%d: %s()", tty->driver->minor_start, tty->index,
+	    __FUNCTION__);
+
+	tty->driver_data = NULL;
+
+	cs = gigaset_get_cs_by_tty(tty);
+	if (!cs)
+		return -ENODEV;
+
+	if (down_interruptible(&cs->sem))
+		return -ERESTARTSYS; // FIXME -EINTR?
+	tty->driver_data = cs;
+
+	++cs->open_count;
+
+	if (cs->open_count == 1) {
+		spin_lock_irqsave(&cs->lock, flags);
+		cs->tty = tty;
+		spin_unlock_irqrestore(&cs->lock, flags);
+		tty->low_latency = 1; //FIXME test
+		//FIXME
+	}
+
+	up(&cs->sem);
+	return 0;
+}
+
+static void if_close(struct tty_struct *tty, struct file *filp)
+{
+	struct cardstate *cs;
+	unsigned long flags;
+
+	cs = (struct cardstate *) tty->driver_data;
+	if (!cs) {
+		err("cs==NULL in %s", __FUNCTION__);
+		return;
+	}
+
+	dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __FUNCTION__);
+
+	down(&cs->sem);
+
+	if (!cs->open_count)
+		warn("%s: device not opened", __FUNCTION__);
+	else {
+		if (!--cs->open_count) {
+			spin_lock_irqsave(&cs->lock, flags);
+			cs->tty = NULL;
+			spin_unlock_irqrestore(&cs->lock, flags);
+			//FIXME
+		}
+	}
+
+	up(&cs->sem);
+}
+
+static int if_ioctl(struct tty_struct *tty, struct file *file,
+                    unsigned int cmd, unsigned long arg)
+{
+	struct cardstate *cs;
+	int retval = -ENODEV;
+	int int_arg;
+	unsigned char buf[6];
+	unsigned version[4];
+
+	cs = (struct cardstate *) tty->driver_data;
+	if (!cs) {
+		err("cs==NULL in %s", __FUNCTION__);
+		return -ENODEV;
+	}
+
+	dbg(DEBUG_IF, "%u: %s(0x%x)", cs->minor_index, __FUNCTION__, cmd);
+
+	if (down_interruptible(&cs->sem))
+		return -ERESTARTSYS; // FIXME -EINTR?
+
+	if (!cs->open_count)
+		warn("%s: device not opened", __FUNCTION__);
+	else {
+		retval = 0;
+		switch (cmd) {
+		case GIGASET_REDIR:
+			retval = get_user(int_arg, (int __user *) arg);
+			if (retval >= 0)
+				retval = if_lock(cs, &int_arg);
+			if (retval >= 0)
+				retval = put_user(int_arg, (int __user *) arg);
+			break;
+		case GIGASET_CONFIG:
+			retval = get_user(int_arg, (int __user *) arg);
+			if (retval >= 0)
+				retval = if_config(cs, &int_arg);
+			if (retval >= 0)
+				retval = put_user(int_arg, (int __user *) arg);
+			break;
+		case GIGASET_BRKCHARS:
+			//FIXME test if MS_LOCKED
+			gigaset_dbg_buffer(DEBUG_IF, "GIGASET_BRKCHARS",
+			                   6, (const unsigned char *) arg, 1);
+			if (!atomic_read(&cs->connected)) {
+				dbg(DEBUG_ANY, "can't communicate with unplugged device");
+				retval = -ENODEV;
+				break;
+			}
+			retval = copy_from_user(&buf,
+			                        (const unsigned char __user *) arg, 6)
+			         ? -EFAULT : 0;
+			if (retval >= 0)
+				retval = cs->ops->brkchars(cs, buf);
+			break;
+		case GIGASET_VERSION:
+			retval = copy_from_user(version, (unsigned __user *) arg,
+			                        sizeof version) ? -EFAULT : 0;
+			if (retval >= 0)
+				retval = if_version(cs, version);
+			if (retval >= 0)
+				retval = copy_to_user((unsigned __user *) arg, version,
+				                      sizeof version)
+				         ? -EFAULT : 0;
+			break;
+	        default:
+			dbg(DEBUG_ANY, "%s: arg not supported - 0x%04x",
+			    __FUNCTION__, cmd);
+			retval = -ENOIOCTLCMD;
+		}
+	}
+
+	up(&cs->sem);
+
+	return retval;
+}
+
+static int if_tiocmget(struct tty_struct *tty, struct file *file)
+{
+	struct cardstate *cs;
+	int retval;
+
+	cs = (struct cardstate *) tty->driver_data;
+	if (!cs) {
+		err("cs==NULL in %s", __FUNCTION__);
+		return -ENODEV;
+	}
+
+	dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __FUNCTION__);
+
+	if (down_interruptible(&cs->sem))
+		return -ERESTARTSYS; // FIXME -EINTR?
+
+	// FIXME read from device?
+	retval = cs->control_state & (TIOCM_RTS|TIOCM_DTR);
+
+	up(&cs->sem);
+
+	return retval;
+}
+
+static int if_tiocmset(struct tty_struct *tty, struct file *file,
+                       unsigned int set, unsigned int clear)
+{
+	struct cardstate *cs;
+	int retval;
+	unsigned mc;
+
+	cs = (struct cardstate *) tty->driver_data;
+	if (!cs) {
+		err("cs==NULL in %s", __FUNCTION__);
+		return -ENODEV;
+	}
+
+	dbg(DEBUG_IF,
+	    "%u: %s(0x%x, 0x%x)", cs->minor_index, __FUNCTION__, set, clear);
+
+	if (down_interruptible(&cs->sem))
+		return -ERESTARTSYS; // FIXME -EINTR?
+
+	if (!atomic_read(&cs->connected)) {
+		dbg(DEBUG_ANY, "can't communicate with unplugged device");
+		retval = -ENODEV;
+	} else {
+		mc = (cs->control_state | set) & ~clear & (TIOCM_RTS|TIOCM_DTR);
+		retval = cs->ops->set_modem_ctrl(cs, cs->control_state, mc);
+		cs->control_state = mc;
+	}
+
+	up(&cs->sem);
+
+	return retval;
+}
+
+static int if_write(struct tty_struct *tty, const unsigned char *buf, int count)
+{
+	struct cardstate *cs;
+	int retval = -ENODEV;
+
+	cs = (struct cardstate *) tty->driver_data;
+	if (!cs) {
+		err("cs==NULL in %s", __FUNCTION__);
+		return -ENODEV;
+	}
+
+	dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __FUNCTION__);
+
+	if (down_interruptible(&cs->sem))
+		return -ERESTARTSYS; // FIXME -EINTR?
+
+	if (!cs->open_count)
+		warn("%s: device not opened", __FUNCTION__);
+	else if (atomic_read(&cs->mstate) != MS_LOCKED) {
+		warn("can't write to unlocked device");
+		retval = -EBUSY;
+	} else if (!atomic_read(&cs->connected)) {
+		dbg(DEBUG_ANY, "can't write to unplugged device");
+		retval = -EBUSY; //FIXME
+	} else {
+		retval = cs->ops->write_cmd(cs, buf, count,
+		                            &cs->if_wake_tasklet);
+	}
+
+	up(&cs->sem);
+
+	return retval;
+}
+
+static int if_write_room(struct tty_struct *tty)
+{
+	struct cardstate *cs;
+	int retval = -ENODEV;
+
+	cs = (struct cardstate *) tty->driver_data;
+	if (!cs) {
+		err("cs==NULL in %s", __FUNCTION__);
+		return -ENODEV;
+	}
+
+	dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __FUNCTION__);
+
+	if (down_interruptible(&cs->sem))
+		return -ERESTARTSYS; // FIXME -EINTR?
+
+	if (!cs->open_count)
+		warn("%s: device not opened", __FUNCTION__);
+	else if (atomic_read(&cs->mstate) != MS_LOCKED) {
+		warn("can't write to unlocked device");
+		retval = -EBUSY; //FIXME
+	} else if (!atomic_read(&cs->connected)) {
+		dbg(DEBUG_ANY, "can't write to unplugged device");
+		retval = -EBUSY; //FIXME
+	} else
+		retval = cs->ops->write_room(cs);
+
+	up(&cs->sem);
+
+	return retval;
+}
+
+static int if_chars_in_buffer(struct tty_struct *tty)
+{
+	struct cardstate *cs;
+	int retval = -ENODEV;
+
+	cs = (struct cardstate *) tty->driver_data;
+	if (!cs) {
+		err("cs==NULL in %s", __FUNCTION__);
+		return -ENODEV;
+	}
+
+	dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __FUNCTION__);
+
+	if (down_interruptible(&cs->sem))
+		return -ERESTARTSYS; // FIXME -EINTR?
+
+	if (!cs->open_count)
+		warn("%s: device not opened", __FUNCTION__);
+	else if (atomic_read(&cs->mstate) != MS_LOCKED) {
+		warn("can't write to unlocked device");
+		retval = -EBUSY;
+	} else if (!atomic_read(&cs->connected)) {
+		dbg(DEBUG_ANY, "can't write to unplugged device");
+		retval = -EBUSY; //FIXME
+	} else
+		retval = cs->ops->chars_in_buffer(cs);
+
+	up(&cs->sem);
+
+	return retval;
+}
+
+static void if_throttle(struct tty_struct *tty)
+{
+	struct cardstate *cs;
+
+	cs = (struct cardstate *) tty->driver_data;
+	if (!cs) {
+		err("cs==NULL in %s", __FUNCTION__);
+		return;
+	}
+
+	dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __FUNCTION__);
+
+	down(&cs->sem);
+
+	if (!cs->open_count)
+		warn("%s: device not opened", __FUNCTION__);
+	else {
+		//FIXME
+	}
+
+	up(&cs->sem);
+}
+
+static void if_unthrottle(struct tty_struct *tty)
+{
+	struct cardstate *cs;
+
+	cs = (struct cardstate *) tty->driver_data;
+	if (!cs) {
+		err("cs==NULL in %s", __FUNCTION__);
+		return;
+	}
+
+	dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __FUNCTION__);
+
+	down(&cs->sem);
+
+	if (!cs->open_count)
+		warn("%s: device not opened", __FUNCTION__);
+	else {
+		//FIXME
+	}
+
+	up(&cs->sem);
+}
+
+static void if_set_termios(struct tty_struct *tty, struct termios *old)
+{
+	struct cardstate *cs;
+	unsigned int iflag;
+	unsigned int cflag;
+	unsigned int old_cflag;
+	unsigned int control_state, new_state;
+
+	cs = (struct cardstate *) tty->driver_data;
+	if (!cs) {
+		err("cs==NULL in %s", __FUNCTION__);
+		return;
+	}
+
+	dbg(DEBUG_IF, "%u: %s()", cs->minor_index, __FUNCTION__);
+
+	down(&cs->sem);
+
+	if (!cs->open_count) {
+		warn("%s: device not opened", __FUNCTION__);
+		goto out;
+	}
+
+	if (!atomic_read(&cs->connected)) {
+		dbg(DEBUG_ANY, "can't communicate with unplugged device");
+		goto out;
+	}
+
+	// stolen from mct_u232.c
+	iflag = tty->termios->c_iflag;
+	cflag = tty->termios->c_cflag;
+	old_cflag = old ? old->c_cflag : cflag; //FIXME?
+	dbg(DEBUG_IF, "%u: iflag %x cflag %x old %x", cs->minor_index,
+	    iflag, cflag, old_cflag);
+
+	/* get a local copy of the current port settings */
+	control_state = cs->control_state;
+
+	/*
+	 * Update baud rate.
+	 * Do not attempt to cache old rates and skip settings,
+	 * disconnects screw such tricks up completely.
+	 * Premature optimization is the root of all evil.
+	 */
+
+        /* reassert DTR and (maybe) RTS on transition from B0 */
+	if ((old_cflag & CBAUD) == B0) {
+		new_state = control_state | TIOCM_DTR;
+		/* don't set RTS if using hardware flow control */
+		if (!(old_cflag & CRTSCTS))
+			new_state |= TIOCM_RTS;
+		dbg(DEBUG_IF, "%u: from B0 - set DTR%s", cs->minor_index,
+		    (new_state & TIOCM_RTS) ? " only" : "/RTS");
+		cs->ops->set_modem_ctrl(cs, control_state, new_state);
+		control_state = new_state;
+	}
+
+	cs->ops->baud_rate(cs, cflag & CBAUD);
+
+	if ((cflag & CBAUD) == B0) {
+		/* Drop RTS and DTR */
+		dbg(DEBUG_IF, "%u: to B0 - drop DTR/RTS", cs->minor_index);
+		new_state = control_state & ~(TIOCM_DTR | TIOCM_RTS);
+		cs->ops->set_modem_ctrl(cs, control_state, new_state);
+		control_state = new_state;
+	}
+
+	/*
+	 * Update line control register (LCR)
+	 */
+
+	cs->ops->set_line_ctrl(cs, cflag);
+
+#if 0
+	//FIXME this hangs M101 [ts 2005-03-09]
+	//FIXME do we need this?
+	/*
+	 * Set flow control: well, I do not really now how to handle DTR/RTS.
+	 * Just do what we have seen with SniffUSB on Win98.
+	 */
+	/* Drop DTR/RTS if no flow control otherwise assert */
+	dbg(DEBUG_IF, "%u: control_state %x", cs->minor_index, control_state);
+	new_state = control_state;
+	if ((iflag & IXOFF) || (iflag & IXON) || (cflag & CRTSCTS))
+		new_state |= TIOCM_DTR | TIOCM_RTS;
+	else
+		new_state &= ~(TIOCM_DTR | TIOCM_RTS);
+	if (new_state != control_state) {
+		dbg(DEBUG_IF, "%u: new_state %x", cs->minor_index, new_state);
+		gigaset_set_modem_ctrl(cs, control_state, new_state); // FIXME: mct_u232.c sets the old state here. is this a bug?
+		control_state = new_state;
+	}
+#endif
+
+	/* save off the modified port settings */
+	cs->control_state = control_state;
+
+out:
+	up(&cs->sem);
+}
+
+
+/* wakeup tasklet for the write operation */
+static void if_wake(unsigned long data)
+{
+	struct cardstate *cs = (struct cardstate *) data;
+	struct tty_struct *tty;
+
+	tty = cs->tty;
+	if (!tty)
+		return;
+
+	if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
+	    tty->ldisc.write_wakeup) {
+		dbg(DEBUG_IF, "write wakeup call");
+		tty->ldisc.write_wakeup(tty);
+	}
+
+	wake_up_interruptible(&tty->write_wait);
+}
+
+/*** interface to common ***/
+
+void gigaset_if_init(struct cardstate *cs)
+{
+	struct gigaset_driver *drv;
+
+	drv = cs->driver;
+	if (!drv->have_tty)
+		return;
+
+	tasklet_init(&cs->if_wake_tasklet, &if_wake, (unsigned long) cs);
+	tty_register_device(drv->tty, cs->minor_index, NULL);
+}
+
+void gigaset_if_free(struct cardstate *cs)
+{
+	struct gigaset_driver *drv;
+
+	drv = cs->driver;
+	if (!drv->have_tty)
+		return;
+
+	tasklet_disable(&cs->if_wake_tasklet);
+	tasklet_kill(&cs->if_wake_tasklet);
+	tty_unregister_device(drv->tty, cs->minor_index);
+}
+
+void gigaset_if_receive(struct cardstate *cs,
+                        unsigned char *buffer, size_t len)
+{
+	unsigned long flags;
+	struct tty_struct *tty;
+
+	spin_lock_irqsave(&cs->lock, flags);
+	if ((tty = cs->tty) == NULL)
+		dbg(DEBUG_ANY, "receive on closed device");
+	else {
+		tty_buffer_request_room(tty, len);
+		tty_insert_flip_string(tty, buffer, len);
+		tty_flip_buffer_push(tty);
+	}
+	spin_unlock_irqrestore(&cs->lock, flags);
+}
+EXPORT_SYMBOL_GPL(gigaset_if_receive);
+
+/* gigaset_if_initdriver
+ * Initialize tty interface.
+ * parameters:
+ *      drv             Driver
+ *      procname        Name of the driver (e.g. for /proc/tty/drivers)
+ *      devname         Name of the device files (prefix without minor number)
+ *      devfsname       Devfs name of the device files without %d
+ */
+void gigaset_if_initdriver(struct gigaset_driver *drv, const char *procname,
+                           const char *devname, const char *devfsname)
+{
+	unsigned minors = drv->minors;
+	int ret;
+	struct tty_driver *tty;
+
+	drv->have_tty = 0;
+
+	if ((drv->tty = alloc_tty_driver(minors)) == NULL)
+		goto enomem;
+	tty = drv->tty;
+
+	tty->magic =		TTY_DRIVER_MAGIC,
+	tty->major =		GIG_MAJOR,
+	tty->type =		TTY_DRIVER_TYPE_SERIAL,
+	tty->subtype =		SERIAL_TYPE_NORMAL,
+	tty->flags =		TTY_DRIVER_REAL_RAW | TTY_DRIVER_NO_DEVFS,
+
+	tty->driver_name =	procname;
+	tty->name =		devname;
+	tty->minor_start =	drv->minor;
+	tty->num =		drv->minors;
+
+	tty->owner =		THIS_MODULE;
+	tty->devfs_name =	devfsname;
+
+	tty->init_termios          = tty_std_termios; //FIXME
+	tty->init_termios.c_cflag  = B9600 | CS8 | CREAD | HUPCL | CLOCAL; //FIXME
+	tty_set_operations(tty, &if_ops);
+
+	ret = tty_register_driver(tty);
+	if (ret < 0) {
+		warn("failed to register tty driver (error %d)", ret);
+		goto error;
+	}
+	dbg(DEBUG_IF, "tty driver initialized");
+	drv->have_tty = 1;
+	return;
+
+enomem:
+	warn("could not allocate tty structures");
+error:
+	if (drv->tty)
+		put_tty_driver(drv->tty);
+}
+
+void gigaset_if_freedriver(struct gigaset_driver *drv)
+{
+	if (!drv->have_tty)
+		return;
+
+	drv->have_tty = 0;
+	tty_unregister_driver(drv->tty);
+	put_tty_driver(drv->tty);
+}