/*
   *  linux/drivers/char/tty_ioctl.c
   *
   *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
   *
   * Modified by Fred N. van Kempen, 01/29/93, to add line disciplines
   * which can be dynamically activated and de-activated by the line
   * discipline handling modules (like SLIP).
   */
  
  #include <linux/types.h>
  #include <linux/termios.h>
  #include <linux/errno.h>
  #include <linux/sched.h>
  #include <linux/kernel.h>
  #include <linux/major.h>
  #include <linux/tty.h>
  #include <linux/fcntl.h>
  #include <linux/string.h>
  #include <linux/mm.h>
  #include <linux/module.h>
  #include <linux/bitops.h>

  #include <linux/mutex.h>

  
  #include <asm/io.h>
  #include <asm/uaccess.h>
  #include <asm/system.h>
  
  #undef TTY_DEBUG_WAIT_UNTIL_SENT
  
  #undef	DEBUG
  
  /*
   * Internal flag options for termios setting behavior
   */
  #define TERMIOS_FLUSH	1
  #define TERMIOS_WAIT	2
  #define TERMIOS_TERMIO	4

  #define TERMIOS_OLD	8

  /**
   *	tty_chars_in_buffer	-	characters pending
   *	@tty: terminal
   *
   *	Return the number of bytes of data in the device private
   *	output queue. If no private method is supplied there is assumed
   *	to be no queue on the device.
   */

  int tty_chars_in_buffer(struct tty_struct *tty)
  {
  	if (tty->ops->chars_in_buffer)
  		return tty->ops->chars_in_buffer(tty);
  	else
  		return 0;
  }

  EXPORT_SYMBOL(tty_chars_in_buffer);

  /**
   *	tty_write_room		-	write queue space
   *	@tty: terminal
   *
   *	Return the number of bytes that can be queued to this device
   *	at the present time. The result should be treated as a guarantee
   *	and the driver cannot offer a value it later shrinks by more than
   *	the number of bytes written. If no method is provided 2K is always
   *	returned and data may be lost as there will be no flow control.
   */
   

  int tty_write_room(struct tty_struct *tty)
  {
  	if (tty->ops->write_room)
  		return tty->ops->write_room(tty);
  	return 2048;
  }

  EXPORT_SYMBOL(tty_write_room);

  /**
   *	tty_driver_flush_buffer	-	discard internal buffer
   *	@tty: terminal
   *
   *	Discard the internal output buffer for this device. If no method
   *	is provided then either the buffer cannot be hardware flushed or
   *	there is no buffer driver side.
   */

  void tty_driver_flush_buffer(struct tty_struct *tty)
  {
  	if (tty->ops->flush_buffer)
  		tty->ops->flush_buffer(tty);
  }

  EXPORT_SYMBOL(tty_driver_flush_buffer);

  /**
   *	tty_throttle		-	flow control
   *	@tty: terminal
   *
   *	Indicate that a tty should stop transmitting data down the stack.

   *	Takes the termios mutex to protect against parallel throttle/unthrottle
   *	and also to ensure the driver can consistently reference its own
   *	termios data at this point when implementing software flow control.

   */

  void tty_throttle(struct tty_struct *tty)
  {

  	mutex_lock(&tty->termios_mutex);

  	/* check TTY_THROTTLED first so it indicates our state */
  	if (!test_and_set_bit(TTY_THROTTLED, &tty->flags) &&
  	    tty->ops->throttle)
  		tty->ops->throttle(tty);

  	mutex_unlock(&tty->termios_mutex);

  }
  EXPORT_SYMBOL(tty_throttle);

  /**
   *	tty_unthrottle		-	flow control
   *	@tty: terminal
   *
   *	Indicate that a tty may continue transmitting data down the stack.

   *	Takes the termios mutex to protect against parallel throttle/unthrottle
   *	and also to ensure the driver can consistently reference its own
   *	termios data at this point when implementing software flow control.
   *
   *	Drivers should however remember that the stack can issue a throttle,
   *	then change flow control method, then unthrottle.

   */

  void tty_unthrottle(struct tty_struct *tty)
  {

  	mutex_lock(&tty->termios_mutex);

  	if (test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
  	    tty->ops->unthrottle)
  		tty->ops->unthrottle(tty);

  	mutex_unlock(&tty->termios_mutex);

  }
  EXPORT_SYMBOL(tty_unthrottle);

  /**
   *	tty_wait_until_sent	-	wait for I/O to finish
   *	@tty: tty we are waiting for
   *	@timeout: how long we will wait
   *
   *	Wait for characters pending in a tty driver to hit the wire, or
   *	for a timeout to occur (eg due to flow control)
   *
   *	Locking: none
   */

  void tty_wait_until_sent(struct tty_struct *tty, long timeout)

  {

  #ifdef TTY_DEBUG_WAIT_UNTIL_SENT
  	char buf[64];

  	printk(KERN_DEBUG "%s wait until sent...
  ", tty_name(tty, buf));
  #endif

  	if (!timeout)
  		timeout = MAX_SCHEDULE_TIMEOUT;

  	if (wait_event_interruptible_timeout(tty->write_wait,

  			!tty_chars_in_buffer(tty), timeout) >= 0) {
  		if (tty->ops->wait_until_sent)
  			tty->ops->wait_until_sent(tty, timeout);

  	}

  }

  EXPORT_SYMBOL(tty_wait_until_sent);

  
  /*
   *		Termios Helper Methods
   */

  static void unset_locked_termios(struct ktermios *termios,
  				 struct ktermios *old,
  				 struct ktermios *locked)

  {
  	int	i;

  
  #define NOSET_MASK(x, y, z) (x = ((x) & ~(z)) | ((y) & (z)))

  
  	if (!locked) {
  		printk(KERN_WARNING "Warning?!? termios_locked is NULL.
  ");
  		return;
  	}
  
  	NOSET_MASK(termios->c_iflag, old->c_iflag, locked->c_iflag);
  	NOSET_MASK(termios->c_oflag, old->c_oflag, locked->c_oflag);
  	NOSET_MASK(termios->c_cflag, old->c_cflag, locked->c_cflag);
  	NOSET_MASK(termios->c_lflag, old->c_lflag, locked->c_lflag);
  	termios->c_line = locked->c_line ? old->c_line : termios->c_line;

  	for (i = 0; i < NCCS; i++)

  		termios->c_cc[i] = locked->c_cc[i] ?
  			old->c_cc[i] : termios->c_cc[i];

  	/* FIXME: What should we do for i/ospeed */

  }

  /*
   * Routine which returns the baud rate of the tty
   *
   * Note that the baud_table needs to be kept in sync with the
   * include/asm/termbits.h file.
   */
  static const speed_t baud_table[] = {
  	0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800,
  	9600, 19200, 38400, 57600, 115200, 230400, 460800,
  #ifdef __sparc__
  	76800, 153600, 307200, 614400, 921600
  #else
  	500000, 576000, 921600, 1000000, 1152000, 1500000, 2000000,
  	2500000, 3000000, 3500000, 4000000
  #endif
  };
  
  #ifndef __sparc__
  static const tcflag_t baud_bits[] = {
  	B0, B50, B75, B110, B134, B150, B200, B300, B600,
  	B1200, B1800, B2400, B4800, B9600, B19200, B38400,
  	B57600, B115200, B230400, B460800, B500000, B576000,
  	B921600, B1000000, B1152000, B1500000, B2000000, B2500000,
  	B3000000, B3500000, B4000000
  };
  #else
  static const tcflag_t baud_bits[] = {
  	B0, B50, B75, B110, B134, B150, B200, B300, B600,
  	B1200, B1800, B2400, B4800, B9600, B19200, B38400,
  	B57600, B115200, B230400, B460800, B76800, B153600,
  	B307200, B614400, B921600
  };
  #endif
  
  static int n_baud_table = ARRAY_SIZE(baud_table);
  
  /**
   *	tty_termios_baud_rate
   *	@termios: termios structure
   *
   *	Convert termios baud rate data into a speed. This should be called
   *	with the termios lock held if this termios is a terminal termios
   *	structure. May change the termios data. Device drivers can call this
   *	function but should use ->c_[io]speed directly as they are updated.
   *
   *	Locking: none
   */
  
  speed_t tty_termios_baud_rate(struct ktermios *termios)
  {
  	unsigned int cbaud;
  
  	cbaud = termios->c_cflag & CBAUD;
  
  #ifdef BOTHER
  	/* Magic token for arbitary speed via c_ispeed/c_ospeed */
  	if (cbaud == BOTHER)
  		return termios->c_ospeed;
  #endif
  	if (cbaud & CBAUDEX) {
  		cbaud &= ~CBAUDEX;
  
  		if (cbaud < 1 || cbaud + 15 > n_baud_table)
  			termios->c_cflag &= ~CBAUDEX;
  		else
  			cbaud += 15;
  	}
  	return baud_table[cbaud];
  }

  EXPORT_SYMBOL(tty_termios_baud_rate);
  
  /**
   *	tty_termios_input_baud_rate
   *	@termios: termios structure
   *
   *	Convert termios baud rate data into a speed. This should be called
   *	with the termios lock held if this termios is a terminal termios
   *	structure. May change the termios data. Device drivers can call this
   *	function but should use ->c_[io]speed directly as they are updated.
   *
   *	Locking: none
   */
  
  speed_t tty_termios_input_baud_rate(struct ktermios *termios)
  {
  #ifdef IBSHIFT
  	unsigned int cbaud = (termios->c_cflag >> IBSHIFT) & CBAUD;
  
  	if (cbaud == B0)
  		return tty_termios_baud_rate(termios);
  
  	/* Magic token for arbitary speed via c_ispeed*/
  	if (cbaud == BOTHER)
  		return termios->c_ispeed;
  
  	if (cbaud & CBAUDEX) {
  		cbaud &= ~CBAUDEX;
  
  		if (cbaud < 1 || cbaud + 15 > n_baud_table)
  			termios->c_cflag &= ~(CBAUDEX << IBSHIFT);
  		else
  			cbaud += 15;
  	}
  	return baud_table[cbaud];
  #else
  	return tty_termios_baud_rate(termios);
  #endif
  }

  EXPORT_SYMBOL(tty_termios_input_baud_rate);

  /**
   *	tty_termios_encode_baud_rate

   *	@termios: ktermios structure holding user requested state

   *	@ispeed: input speed
   *	@ospeed: output speed
   *
   *	Encode the speeds set into the passed termios structure. This is
   *	used as a library helper for drivers os that they can report back
   *	the actual speed selected when it differs from the speed requested
   *

   *	For maximal back compatibility with legacy SYS5/POSIX *nix behaviour
   *	we need to carefully set the bits when the user does not get the
   *	desired speed. We allow small margins and preserve as much of possible
   *	of the input intent to keep compatiblity.

   *
   *	Locking: Caller should hold termios lock. This is already held
   *	when calling this function from the driver termios handler.

   *
   *	The ifdefs deal with platforms whose owners have yet to update them
   *	and will all go away once this is done.

   */

  void tty_termios_encode_baud_rate(struct ktermios *termios,
  				  speed_t ibaud, speed_t obaud)

  {
  	int i = 0;

  	int ifound = -1, ofound = -1;
  	int iclose = ibaud/50, oclose = obaud/50;
  	int ibinput = 0;

  	if (obaud == 0)			/* CD dropped 		  */
  		ibaud = 0;		/* Clear ibaud to be sure */

  	termios->c_ispeed = ibaud;
  	termios->c_ospeed = obaud;

  #ifdef BOTHER

  	/* If the user asked for a precise weird speed give a precise weird
  	   answer. If they asked for a Bfoo speed they many have problems
  	   digesting non-exact replies so fuzz a bit */
  
  	if ((termios->c_cflag & CBAUD) == BOTHER)
  		oclose = 0;
  	if (((termios->c_cflag >> IBSHIFT) & CBAUD) == BOTHER)
  		iclose = 0;
  	if ((termios->c_cflag >> IBSHIFT) & CBAUD)
  		ibinput = 1;	/* An input speed was specified */

  #endif

  	termios->c_cflag &= ~CBAUD;

  	/*
  	 *	Our goal is to find a close match to the standard baud rate
  	 *	returned. Walk the baud rate table and if we get a very close
  	 *	match then report back the speed as a POSIX Bxxxx value by
  	 *	preference
  	 */

  	do {

  		if (obaud - oclose <= baud_table[i] &&
  		    obaud + oclose >= baud_table[i]) {

  			termios->c_cflag |= baud_bits[i];

  			ofound = i;

  		}

  		if (ibaud - iclose <= baud_table[i] &&
  		    ibaud + iclose >= baud_table[i]) {
  			/* For the case input == output don't set IBAUD bits
  			   if the user didn't do so */

  			if (ofound == i && !ibinput)
  				ifound  = i;
  #ifdef IBSHIFT
  			else {
  				ifound = i;

  				termios->c_cflag |= (baud_bits[i] << IBSHIFT);

  			}
  #endif

  		}

  	} while (++i < n_baud_table);

  
  	/*
  	 *	If we found no match then use BOTHER if provided or warn
  	 *	the user their platform maintainer needs to wake up if not.
  	 */
  #ifdef BOTHER

  	if (ofound == -1)

  		termios->c_cflag |= BOTHER;

  	/* Set exact input bits only if the input and output differ or the
  	   user already did */

  	if (ifound == -1 && (ibaud != obaud || ibinput))

  		termios->c_cflag |= (BOTHER << IBSHIFT);

  #else
  	if (ifound == -1 || ofound == -1) {
  		static int warned;
  		if (!warned++)
  			printk(KERN_WARNING "tty: Unable to return correct "
  			  "speed data as your architecture needs updating.
  ");
  	}
  #endif

  }

  EXPORT_SYMBOL_GPL(tty_termios_encode_baud_rate);

  /**
   *	tty_encode_baud_rate		-	set baud rate of the tty
   *	@ibaud: input baud rate
   *	@obad: output baud rate
   *
   *	Update the current termios data for the tty with the new speed
   *	settings. The caller must hold the termios_mutex for the tty in
   *	question.
   */

  void tty_encode_baud_rate(struct tty_struct *tty, speed_t ibaud, speed_t obaud)
  {
  	tty_termios_encode_baud_rate(tty->termios, ibaud, obaud);
  }
  EXPORT_SYMBOL_GPL(tty_encode_baud_rate);

  
  /**
   *	tty_get_baud_rate	-	get tty bit rates
   *	@tty: tty to query
   *
   *	Returns the baud rate as an integer for this terminal. The
   *	termios lock must be held by the caller and the terminal bit
   *	flags may be updated.
   *
   *	Locking: none
   */
  
  speed_t tty_get_baud_rate(struct tty_struct *tty)
  {
  	speed_t baud = tty_termios_baud_rate(tty->termios);
  
  	if (baud == 38400 && tty->alt_speed) {
  		if (!tty->warned) {
  			printk(KERN_WARNING "Use of setserial/setrocket to "
  					    "set SPD_* flags is deprecated
  ");
  			tty->warned = 1;
  		}
  		baud = tty->alt_speed;
  	}
  
  	return baud;
  }

  EXPORT_SYMBOL(tty_get_baud_rate);

  /**

   *	tty_termios_copy_hw	-	copy hardware settings
   *	@new: New termios
   *	@old: Old termios
   *
   *	Propogate the hardware specific terminal setting bits from
   *	the old termios structure to the new one. This is used in cases
   *	where the hardware does not support reconfiguration or as a helper
   *	in some cases where only minimal reconfiguration is supported
   */
  
  void tty_termios_copy_hw(struct ktermios *new, struct ktermios *old)
  {
  	/* The bits a dumb device handles in software. Smart devices need
  	   to always provide a set_termios method */
  	new->c_cflag &= HUPCL | CREAD | CLOCAL;
  	new->c_cflag |= old->c_cflag & ~(HUPCL | CREAD | CLOCAL);
  	new->c_ispeed = old->c_ispeed;
  	new->c_ospeed = old->c_ospeed;
  }

  EXPORT_SYMBOL(tty_termios_copy_hw);
  
  /**

   *	tty_termios_hw_change	-	check for setting change
   *	@a: termios
   *	@b: termios to compare
   *
   *	Check if any of the bits that affect a dumb device have changed
   *	between the two termios structures, or a speed change is needed.
   */
  
  int tty_termios_hw_change(struct ktermios *a, struct ktermios *b)
  {
  	if (a->c_ispeed != b->c_ispeed || a->c_ospeed != b->c_ospeed)
  		return 1;
  	if ((a->c_cflag ^ b->c_cflag) & ~(HUPCL | CREAD | CLOCAL))
  		return 1;
  	return 0;
  }
  EXPORT_SYMBOL(tty_termios_hw_change);
  
  /**

   *	change_termios		-	update termios values
   *	@tty: tty to update
   *	@new_termios: desired new value
   *
   *	Perform updates to the termios values set on this terminal. There
   *	is a bit of layering violation here with n_tty in terms of the
   *	internal knowledge of this function.
   *

   *	Locking: termios_mutex

   */

  static void change_termios(struct tty_struct *tty, struct ktermios *new_termios)

  {

  	struct ktermios old_termios;

  	struct tty_ldisc *ld;

  	unsigned long flags;

  	/*
  	 *	Perform the actual termios internal changes under lock.
  	 */

  
  	/* FIXME: we need to decide on some locking/ordering semantics
  	   for the set_termios notification eventually */

  	mutex_lock(&tty->termios_mutex);

  	old_termios = *tty->termios;

  	*tty->termios = *new_termios;
  	unset_locked_termios(tty->termios, &old_termios, tty->termios_locked);

  
  	/* See if packet mode change of state. */

  	if (tty->link && tty->link->packet) {
  		int old_flow = ((old_termios.c_iflag & IXON) &&
  				(old_termios.c_cc[VSTOP] == '\023') &&
  				(old_termios.c_cc[VSTART] == '\021'));
  		int new_flow = (I_IXON(tty) &&
  				STOP_CHAR(tty) == '\023' &&
  				START_CHAR(tty) == '\021');
  		if (old_flow != new_flow) {

  			spin_lock_irqsave(&tty->ctrl_lock, flags);

  			tty->ctrl_status &= ~(TIOCPKT_DOSTOP | TIOCPKT_NOSTOP);
  			if (new_flow)
  				tty->ctrl_status |= TIOCPKT_DOSTOP;
  			else
  				tty->ctrl_status |= TIOCPKT_NOSTOP;

  			spin_unlock_irqrestore(&tty->ctrl_lock, flags);

  			wake_up_interruptible(&tty->link->read_wait);
  		}
  	}

  	if (tty->ops->set_termios)
  		(*tty->ops->set_termios)(tty, &old_termios);

  	else
  		tty_termios_copy_hw(tty->termios, &old_termios);

  
  	ld = tty_ldisc_ref(tty);
  	if (ld != NULL) {

  		if (ld->ops->set_termios)
  			(ld->ops->set_termios)(tty, &old_termios);

  		tty_ldisc_deref(ld);
  	}

  	mutex_unlock(&tty->termios_mutex);

  }

  /**
   *	set_termios		-	set termios values for a tty
   *	@tty: terminal device
   *	@arg: user data
   *	@opt: option information
   *

   *	Helper function to prepare termios data and run necessary other

   *	functions before using change_termios to do the actual changes.
   *
   *	Locking:

   *		Called functions take ldisc and termios_mutex locks

   */

  static int set_termios(struct tty_struct *tty, void __user *arg, int opt)

  {

  	struct ktermios tmp_termios;

  	struct tty_ldisc *ld;
  	int retval = tty_check_change(tty);
  
  	if (retval)
  		return retval;

  	mutex_lock(&tty->termios_mutex);

  	memcpy(&tmp_termios, tty->termios, sizeof(struct ktermios));

  	mutex_unlock(&tty->termios_mutex);

  	if (opt & TERMIOS_TERMIO) {

  		if (user_termio_to_kernel_termios(&tmp_termios,
  						(struct termio __user *)arg))
  			return -EFAULT;

  #ifdef TCGETS2
  	} else if (opt & TERMIOS_OLD) {

  		if (user_termios_to_kernel_termios_1(&tmp_termios,

  						(struct termios __user *)arg))

  			return -EFAULT;

  	} else {
  		if (user_termios_to_kernel_termios(&tmp_termios,

  						(struct termios2 __user *)arg))

  			return -EFAULT;
  	}

  #else
  	} else if (user_termios_to_kernel_termios(&tmp_termios,
  					(struct termios __user *)arg))
  		return -EFAULT;
  #endif

  	/* If old style Bfoo values are used then load c_ispeed/c_ospeed
  	 * with the real speed so its unconditionally usable */

  	tmp_termios.c_ispeed = tty_termios_input_baud_rate(&tmp_termios);
  	tmp_termios.c_ospeed = tty_termios_baud_rate(&tmp_termios);

  	ld = tty_ldisc_ref(tty);

  	if (ld != NULL) {

  		if ((opt & TERMIOS_FLUSH) && ld->ops->flush_buffer)
  			ld->ops->flush_buffer(tty);

  		tty_ldisc_deref(ld);
  	}

  	if (opt & TERMIOS_WAIT) {
  		tty_wait_until_sent(tty, 0);
  		if (signal_pending(current))
  			return -EINTR;
  	}
  
  	change_termios(tty, &tmp_termios);

  
  	/* FIXME: Arguably if tmp_termios == tty->termios AND the
  	   actual requested termios was not tmp_termios then we may
  	   want to return an error as no user requested change has
  	   succeeded */

  	return 0;
  }

  static void copy_termios(struct tty_struct *tty, struct ktermios *kterm)
  {
  	mutex_lock(&tty->termios_mutex);
  	memcpy(kterm, tty->termios, sizeof(struct ktermios));
  	mutex_unlock(&tty->termios_mutex);
  }
  
  static void copy_termios_locked(struct tty_struct *tty, struct ktermios *kterm)
  {
  	mutex_lock(&tty->termios_mutex);
  	memcpy(kterm, tty->termios_locked, sizeof(struct ktermios));
  	mutex_unlock(&tty->termios_mutex);
  }

  static int get_termio(struct tty_struct *tty, struct termio __user *termio)

  {

  	struct ktermios kterm;
  	copy_termios(tty, &kterm);
  	if (kernel_termios_to_user_termio(termio, &kterm))

  		return -EFAULT;
  	return 0;
  }

  
  #ifdef TCGETX
  
  /**
   *	set_termiox	-	set termiox fields if possible
   *	@tty: terminal
   *	@arg: termiox structure from user
   *	@opt: option flags for ioctl type
   *
   *	Implement the device calling points for the SYS5 termiox ioctl
   *	interface in Linux
   */
  
  static int set_termiox(struct tty_struct *tty, void __user *arg, int opt)
  {
  	struct termiox tnew;
  	struct tty_ldisc *ld;
  
  	if (tty->termiox == NULL)
  		return -EINVAL;
  	if (copy_from_user(&tnew, arg, sizeof(struct termiox)))
  		return -EFAULT;
  
  	ld = tty_ldisc_ref(tty);
  	if (ld != NULL) {
  		if ((opt & TERMIOS_FLUSH) && ld->ops->flush_buffer)
  			ld->ops->flush_buffer(tty);
  		tty_ldisc_deref(ld);
  	}
  	if (opt & TERMIOS_WAIT) {
  		tty_wait_until_sent(tty, 0);
  		if (signal_pending(current))
  			return -EINTR;
  	}
  
  	mutex_lock(&tty->termios_mutex);
  	if (tty->ops->set_termiox)
  		tty->ops->set_termiox(tty, &tnew);
  	mutex_unlock(&tty->termios_mutex);
  	return 0;
  }
  
  #endif

  
  #ifdef TIOCGETP
  /*
   * These are deprecated, but there is limited support..
   *
   * The "sg_flags" translation is a joke..
   */

  static int get_sgflags(struct tty_struct *tty)

  {
  	int flags = 0;
  
  	if (!(tty->termios->c_lflag & ICANON)) {
  		if (tty->termios->c_lflag & ISIG)
  			flags |= 0x02;		/* cbreak */
  		else
  			flags |= 0x20;		/* raw */
  	}
  	if (tty->termios->c_lflag & ECHO)
  		flags |= 0x08;			/* echo */
  	if (tty->termios->c_oflag & OPOST)
  		if (tty->termios->c_oflag & ONLCR)
  			flags |= 0x10;		/* crmod */
  	return flags;
  }

  static int get_sgttyb(struct tty_struct *tty, struct sgttyb __user *sgttyb)

  {
  	struct sgttyb tmp;

  	mutex_lock(&tty->termios_mutex);

  	tmp.sg_ispeed = tty->termios->c_ispeed;
  	tmp.sg_ospeed = tty->termios->c_ospeed;

  	tmp.sg_erase = tty->termios->c_cc[VERASE];
  	tmp.sg_kill = tty->termios->c_cc[VKILL];
  	tmp.sg_flags = get_sgflags(tty);

  	mutex_unlock(&tty->termios_mutex);

  	return copy_to_user(sgttyb, &tmp, sizeof(tmp)) ? -EFAULT : 0;
  }

  static void set_sgflags(struct ktermios *termios, int flags)

  {
  	termios->c_iflag = ICRNL | IXON;
  	termios->c_oflag = 0;
  	termios->c_lflag = ISIG | ICANON;
  	if (flags & 0x02) {	/* cbreak */
  		termios->c_iflag = 0;
  		termios->c_lflag &= ~ICANON;
  	}
  	if (flags & 0x08) {		/* echo */
  		termios->c_lflag |= ECHO | ECHOE | ECHOK |
  				    ECHOCTL | ECHOKE | IEXTEN;
  	}
  	if (flags & 0x10) {		/* crmod */
  		termios->c_oflag |= OPOST | ONLCR;
  	}
  	if (flags & 0x20) {	/* raw */
  		termios->c_iflag = 0;
  		termios->c_lflag &= ~(ISIG | ICANON);
  	}
  	if (!(termios->c_lflag & ICANON)) {
  		termios->c_cc[VMIN] = 1;
  		termios->c_cc[VTIME] = 0;
  	}
  }

  /**
   *	set_sgttyb		-	set legacy terminal values
   *	@tty: tty structure
   *	@sgttyb: pointer to old style terminal structure
   *
   *	Updates a terminal from the legacy BSD style terminal information
   *	structure.
   *

   *	Locking: termios_mutex

   */

  static int set_sgttyb(struct tty_struct *tty, struct sgttyb __user *sgttyb)

  {
  	int retval;
  	struct sgttyb tmp;

  	struct ktermios termios;

  
  	retval = tty_check_change(tty);
  	if (retval)
  		return retval;

  	if (copy_from_user(&tmp, sgttyb, sizeof(tmp)))
  		return -EFAULT;

  	mutex_lock(&tty->termios_mutex);

  	termios = *tty->termios;

  	termios.c_cc[VERASE] = tmp.sg_erase;
  	termios.c_cc[VKILL] = tmp.sg_kill;
  	set_sgflags(&termios, tmp.sg_flags);

  	/* Try and encode into Bfoo format */
  #ifdef BOTHER

  	tty_termios_encode_baud_rate(&termios, termios.c_ispeed,
  						termios.c_ospeed);

  #endif

  	mutex_unlock(&tty->termios_mutex);

  	change_termios(tty, &termios);
  	return 0;
  }
  #endif
  
  #ifdef TIOCGETC

  static int get_tchars(struct tty_struct *tty, struct tchars __user *tchars)

  {
  	struct tchars tmp;

  	mutex_lock(&tty->termios_mutex);

  	tmp.t_intrc = tty->termios->c_cc[VINTR];
  	tmp.t_quitc = tty->termios->c_cc[VQUIT];
  	tmp.t_startc = tty->termios->c_cc[VSTART];
  	tmp.t_stopc = tty->termios->c_cc[VSTOP];
  	tmp.t_eofc = tty->termios->c_cc[VEOF];
  	tmp.t_brkc = tty->termios->c_cc[VEOL2];	/* what is brkc anyway? */

  	mutex_unlock(&tty->termios_mutex);

  	return copy_to_user(tchars, &tmp, sizeof(tmp)) ? -EFAULT : 0;
  }

  static int set_tchars(struct tty_struct *tty, struct tchars __user *tchars)

  {
  	struct tchars tmp;
  
  	if (copy_from_user(&tmp, tchars, sizeof(tmp)))
  		return -EFAULT;

  	mutex_lock(&tty->termios_mutex);

  	tty->termios->c_cc[VINTR] = tmp.t_intrc;
  	tty->termios->c_cc[VQUIT] = tmp.t_quitc;
  	tty->termios->c_cc[VSTART] = tmp.t_startc;
  	tty->termios->c_cc[VSTOP] = tmp.t_stopc;
  	tty->termios->c_cc[VEOF] = tmp.t_eofc;
  	tty->termios->c_cc[VEOL2] = tmp.t_brkc;	/* what is brkc anyway? */

  	mutex_unlock(&tty->termios_mutex);

  	return 0;
  }
  #endif
  
  #ifdef TIOCGLTC

  static int get_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)

  {
  	struct ltchars tmp;

  	mutex_lock(&tty->termios_mutex);

  	tmp.t_suspc = tty->termios->c_cc[VSUSP];

  	/* what is dsuspc anyway? */
  	tmp.t_dsuspc = tty->termios->c_cc[VSUSP];

  	tmp.t_rprntc = tty->termios->c_cc[VREPRINT];

  	/* what is flushc anyway? */
  	tmp.t_flushc = tty->termios->c_cc[VEOL2];

  	tmp.t_werasc = tty->termios->c_cc[VWERASE];
  	tmp.t_lnextc = tty->termios->c_cc[VLNEXT];

  	mutex_unlock(&tty->termios_mutex);

  	return copy_to_user(ltchars, &tmp, sizeof(tmp)) ? -EFAULT : 0;
  }

  static int set_ltchars(struct tty_struct *tty, struct ltchars __user *ltchars)

  {
  	struct ltchars tmp;
  
  	if (copy_from_user(&tmp, ltchars, sizeof(tmp)))
  		return -EFAULT;

  	mutex_lock(&tty->termios_mutex);

  	tty->termios->c_cc[VSUSP] = tmp.t_suspc;

  	/* what is dsuspc anyway? */
  	tty->termios->c_cc[VEOL2] = tmp.t_dsuspc;

  	tty->termios->c_cc[VREPRINT] = tmp.t_rprntc;

  	/* what is flushc anyway? */
  	tty->termios->c_cc[VEOL2] = tmp.t_flushc;

  	tty->termios->c_cc[VWERASE] = tmp.t_werasc;
  	tty->termios->c_cc[VLNEXT] = tmp.t_lnextc;

  	mutex_unlock(&tty->termios_mutex);

  	return 0;
  }
  #endif

  /**
   *	send_prio_char		-	send priority character
   *
   *	Send a high priority character to the tty even if stopped
   *

   *	Locking: none for xchar method, write ordering for write method.

   */

  static int send_prio_char(struct tty_struct *tty, char ch)

  {
  	int	was_stopped = tty->stopped;

  	if (tty->ops->send_xchar) {
  		tty->ops->send_xchar(tty, ch);

  		return 0;

  	}

  	if (tty_write_lock(tty, 0) < 0)

  		return -ERESTARTSYS;

  	if (was_stopped)
  		start_tty(tty);

  	tty->ops->write(tty, &ch, 1);

  	if (was_stopped)
  		stop_tty(tty);

  	tty_write_unlock(tty);

  	return 0;

  }

  /**

   *	tty_change_softcar	-	carrier change ioctl helper
   *	@tty: tty to update
   *	@arg: enable/disable CLOCAL
   *
   *	Perform a change to the CLOCAL state and call into the driver
   *	layer to make it visible. All done with the termios mutex
   */
  
  static int tty_change_softcar(struct tty_struct *tty, int arg)
  {
  	int ret = 0;
  	int bit = arg ? CLOCAL : 0;

  	struct ktermios old;

  
  	mutex_lock(&tty->termios_mutex);

  	old = *tty->termios;

  	tty->termios->c_cflag &= ~CLOCAL;
  	tty->termios->c_cflag |= bit;

  	if (tty->ops->set_termios)
  		tty->ops->set_termios(tty, &old);

  	if ((tty->termios->c_cflag & CLOCAL) != bit)
  		ret = -EINVAL;
  	mutex_unlock(&tty->termios_mutex);
  	return ret;
  }
  
  /**

   *	tty_mode_ioctl		-	mode related ioctls
   *	@tty: tty for the ioctl
   *	@file: file pointer for the tty
   *	@cmd: command
   *	@arg: ioctl argument
   *
   *	Perform non line discipline specific mode control ioctls. This
   *	is designed to be called by line disciplines to ensure they provide
   *	consistent mode setting.
   */

  int tty_mode_ioctl(struct tty_struct *tty, struct file *file,

  			unsigned int cmd, unsigned long arg)

  {

  	struct tty_struct *real_tty;

  	void __user *p = (void __user *)arg;

  	int ret = 0;

  	struct ktermios kterm;

  
  	if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
  	    tty->driver->subtype == PTY_TYPE_MASTER)
  		real_tty = tty->link;
  	else
  		real_tty = tty;
  
  	switch (cmd) {
  #ifdef TIOCGETP

  	case TIOCGETP:
  		return get_sgttyb(real_tty, (struct sgttyb __user *) arg);
  	case TIOCSETP:
  	case TIOCSETN:
  		return set_sgttyb(real_tty, (struct sgttyb __user *) arg);

  #endif
  #ifdef TIOCGETC

  	case TIOCGETC:
  		return get_tchars(real_tty, p);
  	case TIOCSETC:
  		return set_tchars(real_tty, p);

  #endif
  #ifdef TIOCGLTC

  	case TIOCGLTC:
  		return get_ltchars(real_tty, p);
  	case TIOCSLTC:
  		return set_ltchars(real_tty, p);

  #endif

  	case TCSETSF:
  		return set_termios(real_tty, p,  TERMIOS_FLUSH | TERMIOS_WAIT | TERMIOS_OLD);
  	case TCSETSW:
  		return set_termios(real_tty, p, TERMIOS_WAIT | TERMIOS_OLD);
  	case TCSETS:
  		return set_termios(real_tty, p, TERMIOS_OLD);

  #ifndef TCGETS2

  	case TCGETS:

  		copy_termios(real_tty, &kterm);
  		if (kernel_termios_to_user_termios((struct termios __user *)arg, &kterm))

  			ret = -EFAULT;

  		return ret;

  #else

  	case TCGETS:

  		copy_termios(real_tty, &kterm);
  		if (kernel_termios_to_user_termios_1((struct termios __user *)arg, &kterm))

  			ret = -EFAULT;

  		return ret;

  	case TCGETS2:

  		copy_termios(real_tty, &kterm);
  		if (kernel_termios_to_user_termios((struct termios2 __user *)arg, &kterm))

  			ret = -EFAULT;

  		return ret;

  	case TCSETSF2:
  		return set_termios(real_tty, p,  TERMIOS_FLUSH | TERMIOS_WAIT);
  	case TCSETSW2:
  		return set_termios(real_tty, p, TERMIOS_WAIT);
  	case TCSETS2:
  		return set_termios(real_tty, p, 0);

  #endif

  	case TCGETA:
  		return get_termio(real_tty, p);
  	case TCSETAF:
  		return set_termios(real_tty, p, TERMIOS_FLUSH | TERMIOS_WAIT | TERMIOS_TERMIO);
  	case TCSETAW:
  		return set_termios(real_tty, p, TERMIOS_WAIT | TERMIOS_TERMIO);
  	case TCSETA:
  		return set_termios(real_tty, p, TERMIOS_TERMIO);

  #ifndef TCGETS2

  	case TIOCGLCKTRMIOS:

  		copy_termios_locked(real_tty, &kterm);
  		if (kernel_termios_to_user_termios((struct termios __user *)arg, &kterm))

  			ret = -EFAULT;

  		return ret;

  	case TIOCSLCKTRMIOS:
  		if (!capable(CAP_SYS_ADMIN))
  			return -EPERM;

  		copy_termios_locked(real_tty, &kterm);
  		if (user_termios_to_kernel_termios(&kterm,

  					       (struct termios __user *) arg))

  			return -EFAULT;
  		mutex_lock(&real_tty->termios_mutex);
  		memcpy(real_tty->termios_locked, &kterm, sizeof(struct ktermios));

  		mutex_unlock(&real_tty->termios_mutex);

  		return 0;

  #else

  	case TIOCGLCKTRMIOS:

  		copy_termios_locked(real_tty, &kterm);
  		if (kernel_termios_to_user_termios_1((struct termios __user *)arg, &kterm))

  			ret = -EFAULT;

  		return ret;

  	case TIOCSLCKTRMIOS:
  		if (!capable(CAP_SYS_ADMIN))

  			return -EPERM;
  		copy_termios_locked(real_tty, &kterm);
  		if (user_termios_to_kernel_termios_1(&kterm,

  					       (struct termios __user *) arg))

  			return -EFAULT;
  		mutex_lock(&real_tty->termios_mutex);
  		memcpy(real_tty->termios_locked, &kterm, sizeof(struct ktermios));

  		mutex_unlock(&real_tty->termios_mutex);
  		return ret;

  #endif

  #ifdef TCGETX

  	case TCGETX: {
  		struct termiox ktermx;

  		if (real_tty->termiox == NULL)
  			return -EINVAL;

  		mutex_lock(&real_tty->termios_mutex);

  		memcpy(&ktermx, real_tty->termiox, sizeof(struct termiox));

  		mutex_unlock(&real_tty->termios_mutex);

  		if (copy_to_user(p, &ktermx, sizeof(struct termiox)))
  			ret = -EFAULT;

  		return ret;

  	}

  	case TCSETX:
  		return set_termiox(real_tty, p, 0);
  	case TCSETXW:
  		return set_termiox(real_tty, p, TERMIOS_WAIT);
  	case TCSETXF:
  		return set_termiox(real_tty, p, TERMIOS_FLUSH);
  #endif		

  	case TIOCGSOFTCAR:

  		copy_termios(real_tty, &kterm);
  		ret = put_user((kterm.c_cflag & CLOCAL) ? 1 : 0,

  						(int __user *)arg);

  		return ret;

  	case TIOCSSOFTCAR:
  		if (get_user(arg, (unsigned int __user *) arg))
  			return -EFAULT;

  		return tty_change_softcar(real_tty, arg);

  	default:
  		return -ENOIOCTLCMD;

  	}
  }

  EXPORT_SYMBOL_GPL(tty_mode_ioctl);
  
  int tty_perform_flush(struct tty_struct *tty, unsigned long arg)
  {
  	struct tty_ldisc *ld;
  	int retval = tty_check_change(tty);
  	if (retval)
  		return retval;

  	ld = tty_ldisc_ref_wait(tty);

  	switch (arg) {
  	case TCIFLUSH:

  		if (ld && ld->ops->flush_buffer)
  			ld->ops->flush_buffer(tty);

  		break;
  	case TCIOFLUSH:

  		if (ld && ld->ops->flush_buffer)
  			ld->ops->flush_buffer(tty);

  		/* fall through */
  	case TCOFLUSH:

  		tty_driver_flush_buffer(tty);

  		break;
  	default:
  		tty_ldisc_deref(ld);
  		return -EINVAL;
  	}
  	tty_ldisc_deref(ld);
  	return 0;
  }

  EXPORT_SYMBOL_GPL(tty_perform_flush);

  int n_tty_ioctl_helper(struct tty_struct *tty, struct file *file,

  		       unsigned int cmd, unsigned long arg)
  {

  	unsigned long flags;

  	int retval;

  	switch (cmd) {

  	case TCXONC:
  		retval = tty_check_change(tty);
  		if (retval)
  			return retval;
  		switch (arg) {
  		case TCOOFF:
  			if (!tty->flow_stopped) {
  				tty->flow_stopped = 1;
  				stop_tty(tty);

  			}

  			break;
  		case TCOON:
  			if (tty->flow_stopped) {
  				tty->flow_stopped = 0;
  				start_tty(tty);
  			}
  			break;
  		case TCIOFF:
  			if (STOP_CHAR(tty) != __DISABLED_CHAR)
  				return send_prio_char(tty, STOP_CHAR(tty));
  			break;
  		case TCION:
  			if (START_CHAR(tty) != __DISABLED_CHAR)
  				return send_prio_char(tty, START_CHAR(tty));
  			break;

  		default:

  			return -EINVAL;

  		}

  		return 0;
  	case TCFLSH:
  		return tty_perform_flush(tty, arg);

  	case TIOCPKT:
  	{
  		int pktmode;
  
  		if (tty->driver->type != TTY_DRIVER_TYPE_PTY ||
  		    tty->driver->subtype != PTY_TYPE_MASTER)
  			return -ENOTTY;
  		if (get_user(pktmode, (int __user *) arg))
  			return -EFAULT;

  		spin_lock_irqsave(&tty->ctrl_lock, flags);

  		if (pktmode) {
  			if (!tty->packet) {
  				tty->packet = 1;
  				tty->link->ctrl_status = 0;
  			}
  		} else
  			tty->packet = 0;

  		spin_unlock_irqrestore(&tty->ctrl_lock, flags);

  		return 0;
  	}
  	default:
  		/* Try the mode commands */
  		return tty_mode_ioctl(tty, file, cmd, arg);
  	}

  }

  EXPORT_SYMBOL(n_tty_ioctl_helper);