/*
 *  generic_serial.c
 *
 *  Copyright (C) 1998/1999 R.E.Wolff@BitWizard.nl
 *
 *  written for the SX serial driver.
 *     Contains the code that should be shared over all the serial drivers.
 *
 *  Credit for the idea to do it this way might go to Alan Cox. 
 *
 *
 *  Version 0.1 -- December, 1998. Initial version.
 *  Version 0.2 -- March, 1999.    Some more routines. Bugfixes. Etc.
 *  Version 0.5 -- August, 1999.   Some more fixes. Reformat for Linus.
 */

#include <linux/tty.h>
#include <linux/serial.h>
#include <linux/mm.h>
#include <asm/semaphore.h>
#include <linux/version.h>


#if LINUX_VERSION_CODE < 0x020100    /* Less than 2.1.0 */
#define TWO_ZERO
#else
#if LINUX_VERSION_CODE < 0x020200   /* less than 2.2.x */
#warning "Please use a 2.2.x kernel. "
#else
#if LINUX_VERSION_CODE < 0x020300   /* less than 2.2.x */
#define TWO_TWO
#else
#define TWO_THREE
#endif
#endif
#endif

#ifdef TWO_ZERO

/* Here is the section that makes the 2.2 compatible driver source 
   work for 2.0 too! We mostly try to adopt the "new thingies" from 2.2, 
   and provide for compatibility stuff here if possible. */

/* Some 200 days (on intel) */
#define MAX_SCHEDULE_TIMEOUT     ((long)(~0UL>>1))


#ifndef MODULE

#define copy_to_user(a,b,c)          memcpy_tofs(a,b,c)

static inline int copy_from_user(void *to,const void *from, int c) 
{
	memcpy_fromfs(to, from, c);
	return 0;
}


#define capable(x)                   suser()

#define queue_task                   queue_task_irq_off
#define tty_flip_buffer_push(tty)    queue_task(&tty->flip.tqueue, &tq_timer)
#define signal_pending(current)      (current->signal & ~current->blocked)
#define schedule_timeout(to)         do {current->timeout = jiffies + (to);schedule ();} while (0)
#define time_after(t1,t2)            (((long)t1-t2) > 0)

#define test_and_set_bit(nr, addr)   set_bit(nr, addr)
#define test_and_clear_bit(nr, addr) clear_bit(nr, addr)

/* Not yet implemented on 2.0 */
#define ASYNC_SPD_SHI  -1
#define ASYNC_SPD_WARP -1



/* Ugly hack: the driver_name doesn't exist in 2.0.x . So we define it
   to the "name" field that does exist. As long as the assignments are
   done in the right order, there is nothing to worry about. */
#define driver_name           name 


/* Should be in a header somewhere. */
#define TTY_HW_COOK_OUT       14 /* Flag to tell ntty what we can handle */
#define TTY_HW_COOK_IN        15 /* in hardware - output and input       */
#endif

#endif

#ifndef TWO_ZERO
/* This include is new with 2.2  (and required!) */
#include <asm/uaccess.h>
#endif

#ifndef TWO_THREE
/* These are new in 2.3. The source now uses 2.3 syntax, and here is 
   the compatibility define... */
#define wait_queue_head_t struct wait_queue *
#define DECLARE_MUTEX(name) struct semaphore name = MUTEX
#define DECLARE_WAITQUEUE(wait, current) struct wait_queue wait = { current, NULL }

#endif

#include "generic_serial.h"


static char *                  tmp_buf; 
static DECLARE_MUTEX(tmp_buf_sem);

int gs_debug = 0;


#ifdef DEBUG
#define gs_dprintk(f, str...) if (gs_debug & f) printk (str)
#else
#define gs_dprintk(f, str...) /* nothing */
#endif

#define func_enter() gs_dprintk (GS_DEBUG_FLOW, "gs: enter " __FUNCTION__ "\n")
#define func_exit()  gs_dprintk (GS_DEBUG_FLOW, "gs: exit  " __FUNCTION__ "\n")



#if NEW_WRITE_LOCKING
#define DECL      /* Nothing */
#define LOCKIT    down (& port->port_write_sem);
#define RELEASEIT up (&port->port_write_sem);
#else
#define DECL      unsigned long flags;
#define LOCKIT    save_flags (flags);cli ()
#define RELEASEIT restore_flags (flags)
#endif



void gs_put_char(struct tty_struct * tty, unsigned char ch)
{
	struct gs_port *port = tty->driver_data;
	DECL

	/*  func_enter (); */

	/* Take a lock on the serial tranmit buffer! */
	LOCKIT;

	if (port->xmit_cnt >= SERIAL_XMIT_SIZE - 1) {
		/* Sorry, buffer is full, drop character. Update statistics???? -- REW */
		RELEASEIT;
		return;
	}

	port->xmit_buf[port->xmit_head++] = ch;
	port->xmit_head &= SERIAL_XMIT_SIZE - 1;
	port->xmit_cnt++;  /* Characters in buffer */

	RELEASEIT;
	/* func_exit ();*/
}


#ifdef NEW_WRITE_LOCKING

/*
> Problems to take into account are:
>       -1- Interrupts that empty part of the buffer.
>       -2- page faults on the access to userspace. 
>       -3- Other processes that are also trying to do a "write". 
*/

int gs_write(struct tty_struct * tty, int from_user, 
                    const unsigned char *buf, int count)
{
	struct gs_port *port = tty->driver_data;
	int c, total = 0;
	int t;

	/* func_enter (); */

	if (! (port->flags & ASYNC_INITIALIZED))
		return 0;

	/* get exclusive "write" access to this port (problem 3) */
	/* This is not a spinlock because we can have a disk access (page 
		 fault) in copy_from_user */
	down (& port->port_write_sem);

	while (1) {

		c = count;
 
		/* This is safe because we "OWN" the "head". Noone else can 
		   change the "head": we own the port_write_sem. */
		/* Don't overrun the end of the buffer */
		t = SERIAL_XMIT_SIZE - port->xmit_head;
		if (t < c) c = t;
 
		/* This is safe because the xmit_cnt can only decrease. This 
		   would increase "t", so we might copy too little chars. */
		/* Don't copy past the "head" of the buffer */
		t = SERIAL_XMIT_SIZE - 1 - port->xmit_cnt;
		if (t < c) c = t;
 
		/* Can't copy more? break out! */
		if (c <= 0) break;
		if (from_user)
			copy_from_user (port->xmit_buf + port->xmit_head, buf, c);
		else
			memcpy         (port->xmit_buf + port->xmit_head, buf, c);

		port -> xmit_cnt += c;
		port -> xmit_head = (port->xmit_head + c) & (SERIAL_XMIT_SIZE -1);
		buf += c;
		count -= c;
		total += c;
	}
	up (& port->port_write_sem);

	gs_dprintk (GS_DEBUG_WRITE, "write: interrupts are %s\n", 
	            (port->flags & GS_TX_INTEN)?"enabled": "disabled"); 

	if (port->xmit_cnt && 
	    !tty->stopped && 
	    !tty->hw_stopped &&
	    !(port->flags & GS_TX_INTEN)) {
		port->flags |= GS_TX_INTEN;
		port->rd->enable_tx_interrupts (port);
	}
	/* func_exit (); */
	return total;
}
#else
/*
> Problems to take into account are:
>       -1- Interrupts that empty part of the buffer.
>       -2- page faults on the access to userspace. 
>       -3- Other processes that are also trying to do a "write". 
*/

int gs_write(struct tty_struct * tty, int from_user, 
                    const unsigned char *buf, int count)
{
	struct gs_port *port;
	int c, total = 0;
	int t;
	unsigned long flags;

	func_enter ();

	/* The standard serial driver returns 0 in this case. 
	   That sounds to me as "No error, I just didn't get to writing any
	   bytes. Feel free to try again." 
	   The "official" way to write n bytes from buf is:

		 for (nwritten = 0;nwritten < n;nwritten += rv) {
			 rv = write (fd, buf+nwritten, n-nwritten);
			 if (rv < 0) break; // Error: bail out. //
		 } 

	   which will loop endlessly in this case. The manual page for write
	   agrees with me. In practise almost everybody writes 
	   "write (fd, buf,n);" but some people might have had to deal with 
	   incomplete writes in the past and correctly implemented it by now... 
	 */

	if (!tty) return -EIO;

	port = tty->driver_data;
	if (!port || !port->xmit_buf || !tmp_buf)
		return -EIO;

	/* printk ("from_user = %d.\n", from_user); */
	save_flags(flags);
	if (from_user) {
		/* printk ("Going into the semaphore\n"); */
		down(&tmp_buf_sem);
		/* printk ("got out of the semaphore\n"); */
		while (1) {
			c = count;

			/* This is safe because we "OWN" the "head". Noone else can 
			   change the "head": we own the port_write_sem. */
			/* Don't overrun the end of the buffer */
			t = SERIAL_XMIT_SIZE - port->xmit_head;
			if (t < c) c = t;
 
			/* This is safe because the xmit_cnt can only decrease. This 
			   would increase "t", so we might copy too little chars. */
			/* Don't copy past the "head" of the buffer */
			t = SERIAL_XMIT_SIZE - 1 - port->xmit_cnt;
			if (t < c) c = t;	 

			/* Can't copy more? break out! */
			if (c <= 0) break;

			c -= copy_from_user(tmp_buf, buf, c);
			if (!c) {
				if (!total)
					total = -EFAULT;
				break;
			}
			cli();
			t = SERIAL_XMIT_SIZE - port->xmit_head;
			if (t < c) c = t;
			t = SERIAL_XMIT_SIZE - 1 - port->xmit_cnt;
			if (t < c) c = t;

			memcpy(port->xmit_buf + port->xmit_head, tmp_buf, c);
			port->xmit_head = ((port->xmit_head + c) &
			                   (SERIAL_XMIT_SIZE-1));
			port->xmit_cnt += c;
			restore_flags(flags);
			buf += c;
			count -= c;
			total += c;
		}
		up(&tmp_buf_sem);
	} else {
		while (1) {
			cli();
			c = count;

			/* This is safe because we "OWN" the "head". Noone else can 
			   change the "head": we own the port_write_sem. */
			/* Don't overrun the end of the buffer */
			t = SERIAL_XMIT_SIZE - port->xmit_head;
			if (t < c) c = t;
 
			/* This is safe because the xmit_cnt can only decrease. This 
			   would increase "t", so we might copy too little chars. */
			/* Don't copy past the "head" of the buffer */
			t = SERIAL_XMIT_SIZE - 1 - port->xmit_cnt;
			if (t < c) c = t;
 
			/* Can't copy more? break out! */
			if (c <= 0) {
				restore_flags(flags);
				break;
			}
			memcpy(port->xmit_buf + port->xmit_head, buf, c);
			port->xmit_head = ((port->xmit_head + c) &
			                   (SERIAL_XMIT_SIZE-1));
			port->xmit_cnt += c;
			restore_flags(flags);
			buf += c;
			count -= c;
			total += c;
		}
	}

	if (port->xmit_cnt && 
	    !tty->stopped && 
	    !tty->hw_stopped &&
	    !(port->flags & GS_TX_INTEN)) {
		port->flags |= GS_TX_INTEN;
		port->rd->enable_tx_interrupts (port);
	}
	func_exit ();
	return total;
}

#endif



int gs_write_room(struct tty_struct * tty)
{
	struct gs_port *port = tty->driver_data;
	int ret;

	/* func_enter (); */
	ret = SERIAL_XMIT_SIZE - port->xmit_cnt - 1;
	if (ret < 0)
		ret = 0;
	/* func_exit (); */
	return ret;
}


int gs_chars_in_buffer(struct tty_struct *tty)
{
	struct gs_port *port = tty->driver_data;
	func_enter ();

	func_exit ();
	return port->xmit_cnt;
}


int gs_real_chars_in_buffer(struct tty_struct *tty)
{
	struct gs_port *port = tty->driver_data;
	func_enter ();

	if (!tty) return 0;
	port = tty->driver_data;

	func_exit ();
	return port->xmit_cnt + port->rd->chars_in_buffer (port);
}


static void gs_wait_tx_flushed (void * ptr, int timeout) 
{
	struct gs_port *port = ptr;
	long end_jiffies;
	int jiffies_to_transmit, charsleft;
	int to, rcib;

	func_enter();

	gs_dprintk (GS_DEBUG_FLUSH, "port=%p.\n", port);
	if (port) {
		gs_dprintk (GS_DEBUG_FLUSH, "xmit_cnt=%x, xmit_buf=%p, tty=%p.\n", 
		port->xmit_cnt, port->xmit_buf, port->tty);
	}

	if (!port || port->xmit_cnt < 0 || !port->xmit_buf) {
		gs_dprintk (GS_DEBUG_FLUSH, "ERROR: !port, !port->xmit_buf or prot->xmit_cnt < 0.\n");
	func_exit();
		return;  /* This is an error which we don't know how to handle. */
	}
	gs_dprintk (GS_DEBUG_FLUSH, "checkpoint 1\n");

	rcib = gs_real_chars_in_buffer(port->tty);

	gs_dprintk (GS_DEBUG_FLUSH, "checkpoint 2\n");

	if(rcib <= 0) {
		gs_dprintk (GS_DEBUG_FLUSH, "nothing to wait for.\n");
	func_exit();
	return;
	}
	gs_dprintk (GS_DEBUG_FLUSH, "checkpoint 3\n");

	/* stop trying: now + twice the time it would normally take +  seconds */
	end_jiffies  = jiffies; 
	if (timeout !=  MAX_SCHEDULE_TIMEOUT)
		end_jiffies += port->baud?(2 * rcib * 10 * HZ / port->baud):0;
	end_jiffies += timeout;

	gs_dprintk (GS_DEBUG_FLUSH, "now=%lx, end=%lx (%ld).\n", 
		    jiffies, end_jiffies, end_jiffies-jiffies); 

	to = 100;
	/* the expression is actually jiffies < end_jiffies, but that won't
	   work around the wraparound. Tricky eh? */
	while (to-- &&
	       (charsleft = gs_real_chars_in_buffer (port->tty)) &&
	        time_after (end_jiffies, jiffies)) {
		/* Units check: 
		   chars * (bits/char) * (jiffies /sec) / (bits/sec) = jiffies!
		   check! */

		charsleft += 16; /* Allow 16 chars more to be transmitted ... */
		jiffies_to_transmit = port->baud?(1 + charsleft * 10 * HZ / port->baud):0;
		/*                                ^^^ Round up.... */
		if (jiffies_to_transmit <= 0) jiffies_to_transmit = 1;

		gs_dprintk (GS_DEBUG_FLUSH, "Expect to finish in %d jiffies "
			    "(%d chars).\n", jiffies_to_transmit, charsleft); 

		current->state = TASK_INTERRUPTIBLE;
		schedule_timeout(jiffies_to_transmit);
		if (signal_pending (current))
			break;
	}

	gs_dprintk (GS_DEBUG_FLUSH, "charsleft = %d.\n", charsleft); 
	current->state = TASK_RUNNING;

	func_exit();
}



void gs_flush_buffer(struct tty_struct *tty)
{
	struct gs_port *port = tty->driver_data;
	unsigned long flags;

	func_enter ();
	/* XXX Would the write semaphore do? */
	save_flags(flags); cli();
	port->xmit_cnt = port->xmit_head = port->xmit_tail = 0;
	restore_flags(flags);

	wake_up_interruptible(&tty->write_wait);
	if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
	    tty->ldisc.write_wakeup)
		(tty->ldisc.write_wakeup)(tty);
	func_exit ();
}


void gs_flush_chars(struct tty_struct * tty)
{
	struct gs_port *port = tty->driver_data;

	func_enter ();
	if (port->xmit_cnt <= 0 || tty->stopped || tty->hw_stopped ||
	    !port->xmit_buf) {
		func_exit ();
		return;
	}

	/* Beats me -- REW */
	port->flags |= GS_TX_INTEN;
	port->rd->enable_tx_interrupts (port);
	func_exit ();
}


void gs_stop(struct tty_struct * tty)
{
	struct gs_port *port = tty->driver_data;

	func_enter ();
	if (port->xmit_cnt && 
	    port->xmit_buf && 
	    (port->flags & GS_TX_INTEN) ) {
		port->flags &= ~GS_TX_INTEN;
		port->rd->disable_tx_interrupts (port);
	}
	func_exit ();
}


void gs_start(struct tty_struct * tty)
{
	struct gs_port *port = tty->driver_data;

	if (port->xmit_cnt && 
	    port->xmit_buf && 
	    !(port->flags & GS_TX_INTEN) ) {
		port->flags |= GS_TX_INTEN;
		port->rd->enable_tx_interrupts (port);
	}
	func_exit ();
}


void gs_shutdown_port (struct gs_port *port)
{
	long flags;

	if (!(port->flags & ASYNC_INITIALIZED))
		return;

	save_flags (flags);
	cli ();

	if (port->xmit_buf) {
		free_page((unsigned long) port->xmit_buf);
		port->xmit_buf = 0;
	}

	if (port->tty)
		set_bit(TTY_IO_ERROR, &port->tty->flags);

	port->rd->shutdown_port (port);

	port->flags &= ~ASYNC_INITIALIZED;
	restore_flags (flags);
}


void gs_hangup(struct tty_struct *tty)
{
	struct gs_port   *port = tty->driver_data;

	func_enter ();

	tty = port->tty;
	if (!tty) return;

	gs_shutdown_port (port);

	/* gs_flush_buffer (tty); */
	port->flags &= ~(ASYNC_NORMAL_ACTIVE|ASYNC_CALLOUT_ACTIVE |GS_ACTIVE);
	port->tty = NULL;
	port->count = 0;

	wake_up_interruptible(&port->open_wait);
	func_exit ();
}


void gs_do_softint(void *private_)
{
	struct gs_port *port = private_;
	struct tty_struct *tty;

	tty = port->tty;
	if(!tty) return;

	if (test_and_clear_bit(RS_EVENT_WRITE_WAKEUP, &port->event)) {
		if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
		    tty->ldisc.write_wakeup)
			(tty->ldisc.write_wakeup)(tty);
		wake_up_interruptible(&tty->write_wait);
	}
	func_exit ();
}


int block_til_ready(void *port_, struct file * filp)
{
	struct gs_port *port = port_;
	DECLARE_WAITQUEUE(wait, current);
	int    retval;
	int    do_clocal = 0;
	int    CD;
	struct tty_struct *tty;

	func_enter ();
	tty = port->tty;

	gs_dprintk (GS_DEBUG_BTR, "Entering block_till_ready.\n"); 
	/*
	 * If the device is in the middle of being closed, then block
	 * until it's done, and then try again.
	 */
	if (tty_hung_up_p(filp) || port->flags & ASYNC_CLOSING) {
	  interruptible_sleep_on(&port->close_wait);
		if (port->flags & ASYNC_HUP_NOTIFY)
			return -EAGAIN;
		else
			return -ERESTARTSYS;
	}

	gs_dprintk (GS_DEBUG_BTR, "after hung up\n"); 

	/*
	 * If this is a callout device, then just make sure the normal
	 * device isn't being used.
	 */
	if (tty->driver.subtype == GS_TYPE_CALLOUT) {
		if (port->flags & ASYNC_NORMAL_ACTIVE)
			return -EBUSY;
		if ((port->flags & ASYNC_CALLOUT_ACTIVE) &&
		    (port->flags & ASYNC_SESSION_LOCKOUT) &&
		    (port->session != current->session))
			return -EBUSY;
		if ((port->flags & ASYNC_CALLOUT_ACTIVE) &&
		    (port->flags & ASYNC_PGRP_LOCKOUT) &&
		    (port->pgrp != current->pgrp))
			return -EBUSY;
		port->flags |= ASYNC_CALLOUT_ACTIVE;
		return 0;
	}

	gs_dprintk (GS_DEBUG_BTR, "after subtype\n");

	/*
	 * If non-blocking mode is set, or the port is not enabled,
	 * then make the check up front and then exit.
	 */
	if ((filp->f_flags & O_NONBLOCK) ||
	    (tty->flags & (1 << TTY_IO_ERROR))) {
		if (port->flags & ASYNC_CALLOUT_ACTIVE)
			return -EBUSY;
		port->flags |= ASYNC_NORMAL_ACTIVE;
		return 0;
	}

	gs_dprintk (GS_DEBUG_BTR, "after nonblock\n"); 
 
	if (port->flags & ASYNC_CALLOUT_ACTIVE) {
		if (port->normal_termios.c_cflag & CLOCAL) 
			do_clocal = 1;
	} else {
		if (C_CLOCAL(tty))
			do_clocal = 1;
	}

	gs_dprintk (GS_DEBUG_BTR, "after clocal check.\n"); 

	/*
	 * Block waiting for the carrier detect and the line to become
	 * free (i.e., not in use by the callout).  While we are in
	 * this loop, port->count is dropped by one, so that
	 * rs_close() knows when to free things.  We restore it upon
	 * exit, either normal or abnormal.
	 */
	retval = 0;
	add_wait_queue(&port->open_wait, &wait);

	gs_dprintk (GS_DEBUG_BTR, "after add waitq.\n"); 

	cli();
	if (!tty_hung_up_p(filp))
		port->count--;
	sti();
	port->blocked_open++;
	while (1) {
		CD = port->rd->get_CD (port);
		gs_dprintk (GS_DEBUG_BTR, "CD is now %d.\n", CD);
		set_current_state(TASK_INTERRUPTIBLE);
		if (tty_hung_up_p(filp) ||
		    !(port->flags & ASYNC_INITIALIZED)) {
			if (port->flags & ASYNC_HUP_NOTIFY)
				retval = -EAGAIN;
			else
				retval = -ERESTARTSYS;
			break;
		}
		if (!(port->flags & ASYNC_CALLOUT_ACTIVE) &&
		    !(port->flags & ASYNC_CLOSING) &&
		    (do_clocal || CD))
			break;
		gs_dprintk (GS_DEBUG_BTR, "signal_pending is now: %d (%lx)\n", 
		(int)signal_pending (current), *(long*)(&current->blocked)); 
		if (signal_pending(current)) {
			retval = -ERESTARTSYS;
			break;
		}
		schedule();
	}
	gs_dprintk (GS_DEBUG_BTR, "Got out of the loop. (%d)\n",
		    port->blocked_open);
	current->state = TASK_RUNNING;
	remove_wait_queue(&port->open_wait, &wait);
	if (!tty_hung_up_p(filp))
		port->count++;
	port->blocked_open--;
	if (retval)
		return retval;

	port->flags |= ASYNC_NORMAL_ACTIVE;
	func_exit ();
	return 0;
}			 


void gs_close(struct tty_struct * tty, struct file * filp)
{
	unsigned long flags;
	struct gs_port *port;

	func_enter ();
	port = (struct gs_port *) tty->driver_data;

	gs_dprintk (GS_DEBUG_CLOSE, "tty=%p, port=%p port->tty=%p\n",
	            tty, port, port->tty);

	if(! port) {
		func_exit();
		return;
	}
	if (!port->tty) {
		printk (KERN_WARNING "gs: Odd: port->tty is NULL\n");
		port->tty = tty;
	}


	save_flags(flags); cli();

	if (tty_hung_up_p(filp)) {
		restore_flags(flags);
		port->rd->hungup (port);
		func_exit ();
		return;
	}

	if ((tty->count == 1) && (port->count != 1)) {
		printk(KERN_ERR "gs: gs_close: bad port count;"
		       " tty->count is 1, port count is %d\n", port->count);
		port->count = 1;
	}
	if (--port->count < 0) {
		printk(KERN_ERR "gs: gs_close: bad port count: %d\n", port->count);
		port->count = 0;
	}
	if (port->count) {
		restore_flags(flags);
		func_exit ();
		return;
	}
	port->flags |= ASYNC_CLOSING;

	/*
	 * Save the termios structure, since this port may have
	 * separate termios for callout and dialin.
	 */
	if (port->flags & ASYNC_NORMAL_ACTIVE)
		port->normal_termios = *tty->termios;
	if (port->flags & ASYNC_CALLOUT_ACTIVE)
		port->callout_termios = *tty->termios;
	/*
	 * Now we wait for the transmit buffer to clear; and we notify 
	 * the line discipline to only process XON/XOFF characters.
	 */
	tty->closing = 1;
	/* if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
	   tty_wait_until_sent(tty, port->closing_wait); */

	/*
	 * At this point we stop accepting input.  To do this, we
	 * disable the receive line status interrupts, and tell the
	 * interrupt driver to stop checking the data ready bit in the
	 * line status register.
	 */

	port->rd->disable_rx_interrupts (port);

	if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
		gs_wait_tx_flushed (port, port->closing_wait); 

	port->flags &= ~GS_ACTIVE;

	if (tty->driver.flush_buffer)
		tty->driver.flush_buffer(tty);
	if (tty->ldisc.flush_buffer)
		tty->ldisc.flush_buffer(tty);
	tty->closing = 0;
	port->event = 0;
	port->tty = 0;
	if (port->blocked_open) {
		if (port->close_delay) {
			current->state = TASK_INTERRUPTIBLE;
			schedule_timeout(port->close_delay);
		}
		wake_up_interruptible(&port->open_wait);
	}
	port->flags &= ~(ASYNC_NORMAL_ACTIVE|ASYNC_CALLOUT_ACTIVE|
	                 ASYNC_CLOSING | ASYNC_INITIALIZED);
	wake_up_interruptible(&port->close_wait);

	port->rd->close (port);
	port->rd->shutdown_port (port);
	restore_flags(flags);
	func_exit ();
}


static unsigned int     gs_baudrates[] = {
  0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800,
  9600, 19200, 38400, 57600, 115200, 230400, 460800, 921600
};


void gs_set_termios (struct tty_struct * tty, 
                     struct termios * old_termios)
{
	struct gs_port *port = tty->driver_data;
	int baudrate, tmp;
	struct termios *tiosp;

	func_enter();

	tiosp = tty->termios;


	if (gs_debug & GS_DEBUG_TERMIOS) {
		gs_dprintk (GS_DEBUG_TERMIOS, "termios structure (%p):\n", tiosp);
	}

#if 0
	/* This is an optimization that is only allowed for dumb cards */
	/* Smart cards require knowledge of iflags and oflags too: that 
	   might change hardware cooking mode.... */
#endif
	if (old_termios) {
		if(   (tiosp->c_iflag == old_termios->c_iflag)
		   && (tiosp->c_oflag == old_termios->c_oflag)
		   && (tiosp->c_cflag == old_termios->c_cflag)
		   && (tiosp->c_lflag == old_termios->c_lflag)
		   && (tiosp->c_line  == old_termios->c_line)
		   && (memcmp(tiosp->c_cc, old_termios->c_cc, NCC) == 0)) {
			gs_dprintk(GS_DEBUG_TERMIOS, "gs_set_termios: optimized away\n");
			return;
		}
	} else 
		gs_dprintk(GS_DEBUG_TERMIOS, "gs_set_termios: no old_termios: "
		           "no optimization\n");

	if(old_termios && (gs_debug & GS_DEBUG_TERMIOS)) {
		if(tiosp->c_iflag != old_termios->c_iflag)  printk("c_iflag changed\n");
		if(tiosp->c_oflag != old_termios->c_oflag)  printk("c_oflag changed\n");
		if(tiosp->c_cflag != old_termios->c_cflag)  printk("c_cflag changed\n");
		if(tiosp->c_lflag != old_termios->c_lflag)  printk("c_lflag changed\n");
		if(tiosp->c_line  != old_termios->c_line)   printk("c_line changed\n");
		if(!memcmp(tiosp->c_cc, old_termios->c_cc, NCC)) printk("c_cc changed\n");
	}

	baudrate = tiosp->c_cflag & CBAUD;
	if (baudrate & CBAUDEX) {
		baudrate &= ~CBAUDEX;
		if ((baudrate < 1) || (baudrate > 4))
			tiosp->c_cflag &= ~CBAUDEX;
		else
			baudrate += 15;
	}

	baudrate = gs_baudrates[baudrate];
	if ((tiosp->c_cflag & CBAUD) == B38400) {
		if (     (port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI)
			baudrate = 57600;
		else if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_VHI)
			baudrate = 115200;
		else if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_SHI)
			baudrate = 230400;
		else if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_WARP)
			baudrate = 460800;
		else if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_CUST)
			baudrate = (port->baud_base / port->custom_divisor);
	}

	/* I recommend using THIS instead of the mess in termios (and
	   duplicating the above code). Next we should create a clean
	   interface towards this variable. If your card supports arbitrary
	   baud rates, (e.g. CD1400 or 16550 based cards) then everything
	   will be very easy..... */
	port->baud = baudrate;

	/* Two timer ticks seems enough to wakeup something like SLIP driver */
	/* Baudrate/10 is cps. Divide by HZ to get chars per tick. */
	tmp = (baudrate / 10 / HZ) * 2;			 

	if (tmp <                 0) tmp = 0;
	if (tmp >= SERIAL_XMIT_SIZE) tmp = SERIAL_XMIT_SIZE-1;

	port->wakeup_chars = tmp;

	/* We should really wait for the characters to be all sent before
	   changing the settings. -- CAL */
	gs_wait_tx_flushed (port, MAX_SCHEDULE_TIMEOUT);

	port->rd->set_real_termios(port);

	if ((!old_termios || 
	     (old_termios->c_cflag & CRTSCTS)) &&
	    !(      tiosp->c_cflag & CRTSCTS)) {
		tty->stopped = 0;
		gs_start(tty);
	}

#ifdef tytso_patch_94Nov25_1726
	/* This "makes sense", Why is it commented out? */

	if (!(old_termios->c_cflag & CLOCAL) &&
	    (tty->termios->c_cflag & CLOCAL))
		wake_up_interruptible(&info->open_wait);
#endif

	func_exit();
	return;
}



/* Must be called with interrupts enabled */
int gs_init_port(struct gs_port *port)
{
	unsigned long flags;
	unsigned long page;

	save_flags (flags);
	if (!tmp_buf) {
		page = get_free_page(GFP_KERNEL);

		cli (); /* Don't expect this to make a difference. */ 
		if (tmp_buf)
			free_page(page);
		else
			tmp_buf = (unsigned char *) page;
		restore_flags (flags);

		if (!tmp_buf) {
			return -ENOMEM;
		}
	}

	if (port->flags & ASYNC_INITIALIZED)
		return 0;

	if (!port->xmit_buf) {
		/* We may sleep in get_free_page() */
		unsigned long tmp;

		tmp = get_free_page(GFP_KERNEL);

		/* Spinlock? */
		cli ();
		if (port->xmit_buf) 
			free_page (tmp);
		else
			port->xmit_buf = (unsigned char *) tmp;
		restore_flags (flags);

		if (!port->xmit_buf)
			return -ENOMEM;
	}

	cli();

	if (port->tty) 
		clear_bit(TTY_IO_ERROR, &port->tty->flags);

	port->xmit_cnt = port->xmit_head = port->xmit_tail = 0;

	gs_set_termios(port->tty, NULL);

	port->flags |= ASYNC_INITIALIZED;
	port->flags &= ~GS_TX_INTEN;

	restore_flags(flags);
	return 0;
}


int gs_setserial(struct gs_port *port, struct serial_struct *sp)
{
	struct serial_struct sio;

	copy_from_user(&sio, sp, sizeof(struct serial_struct));

	if (!capable(CAP_SYS_ADMIN)) {
		if ((sio.baud_base != port->baud_base) ||
		    (sio.close_delay != port->close_delay) ||
		    ((sio.flags & ~ASYNC_USR_MASK) !=
		     (port->flags & ~ASYNC_USR_MASK)))
			return(-EPERM);
	} 

	port->flags = (port->flags & ~ASYNC_USR_MASK) |
		(sio.flags & ASYNC_USR_MASK);
  
	port->baud_base = sio.baud_base;
	port->close_delay = sio.close_delay;
	port->closing_wait = sio.closing_wait;
	port->custom_divisor = sio.custom_divisor;

	gs_set_termios (port->tty, NULL);

	return 0;
}


/*****************************************************************************/

/*
 *      Generate the serial struct info.
 */

void gs_getserial(struct gs_port *port, struct serial_struct *sp)
{
	struct serial_struct    sio;

	memset(&sio, 0, sizeof(struct serial_struct));
	sio.flags = port->flags;
	sio.baud_base = port->baud_base;
	sio.close_delay = port->close_delay;
	sio.closing_wait = port->closing_wait;
	sio.custom_divisor = port->custom_divisor;
	sio.hub6 = 0;

	/* If you want you can override these. */
	sio.type = PORT_UNKNOWN;
	sio.xmit_fifo_size = -1;
	sio.line = -1;
	sio.port = -1;
	sio.irq = -1;

	if (port->rd->getserial)
		port->rd->getserial (port, &sio);

	copy_to_user(sp, &sio, sizeof(struct serial_struct));
}