Commit 46d57a44 authored by Alan Cox's avatar Alan Cox Committed by Live-CD User
Browse files

serial: use tty_port pointers in the core code 



Extract out a lot of the x.port. uses and also show up where there are
things left to be isolated that prevent use using the port helpers in the
serial layer at this point

Signed-off-by: default avatarAlan Cox <alan@linux.intel.com>
parent 5e99df56

drivers/serial/serial_core.c

+146 −142
Original line number Diff line number Diff line
@@ -141,7 +141,8 @@ uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear) 
 */

static int uart_startup(struct uart_state *state, int init_hw)

{

	struct uart_port *port = state->uart_port;

	struct uart_port *uport = state->uart_port;

	struct tty_port *port = &state->port;

	unsigned long page;

	int retval = 0;
@@ -153,9 +154,9 @@ static int uart_startup(struct uart_state *state, int init_hw) 
	 * once we have successfully opened the port.  Also set

	 * up the tty->alt_speed kludge

	 */

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

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



	if (port->type == PORT_UNKNOWN)

	if (uport->type == PORT_UNKNOWN)

		return 0;



	/*
@@ -172,7 +173,7 @@ static int uart_startup(struct uart_state *state, int init_hw) 
		uart_circ_clear(&state->xmit);

	}



	retval = port->ops->startup(port);

	retval = uport->ops->startup(uport);

	if (retval == 0) {

		if (init_hw) {

			/*
@@ -184,20 +185,20 @@ static int uart_startup(struct uart_state *state, int init_hw) 
			 * Setup the RTS and DTR signals once the

			 * port is open and ready to respond.

			 */

			if (state->port.tty->termios->c_cflag & CBAUD)

				uart_set_mctrl(port, TIOCM_RTS | TIOCM_DTR);

			if (port->tty->termios->c_cflag & CBAUD)

				uart_set_mctrl(uport, TIOCM_RTS | TIOCM_DTR);

		}



		if (state->flags & UIF_CTS_FLOW) {

			spin_lock_irq(&port->lock);

			if (!(port->ops->get_mctrl(port) & TIOCM_CTS))

				state->port.tty->hw_stopped = 1;

			spin_unlock_irq(&port->lock);

			spin_lock_irq(&uport->lock);

			if (!(uport->ops->get_mctrl(uport) & TIOCM_CTS))

				port->tty->hw_stopped = 1;

			spin_unlock_irq(&uport->lock);

		}



		state->flags |= UIF_INITIALIZED;



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

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

	}



	if (retval && capable(CAP_SYS_ADMIN))
@@ -672,7 +673,8 @@ static int uart_set_info(struct uart_state *state, 
			 struct serial_struct __user *newinfo)

{

	struct serial_struct new_serial;

	struct uart_port *port = state->uart_port;

	struct uart_port *uport = state->uart_port;

	struct tty_port *port = &state->port;

	unsigned long new_port;

	unsigned int change_irq, change_port, closing_wait;

	unsigned int old_custom_divisor, close_delay;
@@ -700,47 +702,47 @@ static int uart_set_info(struct uart_state *state, 
	 */

	mutex_lock(&state->mutex);



	change_irq  = !(port->flags & UPF_FIXED_PORT)

		&& new_serial.irq != port->irq;

	change_irq  = !(uport->flags & UPF_FIXED_PORT)

		&& new_serial.irq != uport->irq;



	/*

	 * Since changing the 'type' of the port changes its resource

	 * allocations, we should treat type changes the same as

	 * IO port changes.

	 */

	change_port = !(port->flags & UPF_FIXED_PORT)

		&& (new_port != port->iobase ||

		    (unsigned long)new_serial.iomem_base != port->mapbase ||

		    new_serial.hub6 != port->hub6 ||

		    new_serial.io_type != port->iotype ||

		    new_serial.iomem_reg_shift != port->regshift ||

		    new_serial.type != port->type);

	change_port = !(uport->flags & UPF_FIXED_PORT)

		&& (new_port != uport->iobase ||

		    (unsigned long)new_serial.iomem_base != uport->mapbase ||

		    new_serial.hub6 != uport->hub6 ||

		    new_serial.io_type != uport->iotype ||

		    new_serial.iomem_reg_shift != uport->regshift ||

		    new_serial.type != uport->type);



	old_flags = port->flags;

	old_flags = uport->flags;

	new_flags = new_serial.flags;

	old_custom_divisor = port->custom_divisor;

	old_custom_divisor = uport->custom_divisor;



	if (!capable(CAP_SYS_ADMIN)) {

		retval = -EPERM;

		if (change_irq || change_port ||

		    (new_serial.baud_base != port->uartclk / 16) ||

		    (close_delay != state->port.close_delay) ||

		    (closing_wait != state->port.closing_wait) ||

		    (new_serial.baud_base != uport->uartclk / 16) ||

		    (close_delay != port->close_delay) ||

		    (closing_wait != port->closing_wait) ||

		    (new_serial.xmit_fifo_size &&

		     new_serial.xmit_fifo_size != port->fifosize) ||

		     new_serial.xmit_fifo_size != uport->fifosize) ||

		    (((new_flags ^ old_flags) & ~UPF_USR_MASK) != 0))

			goto exit;

		port->flags = ((port->flags & ~UPF_USR_MASK) |

		uport->flags = ((uport->flags & ~UPF_USR_MASK) |

			       (new_flags & UPF_USR_MASK));

		port->custom_divisor = new_serial.custom_divisor;

		uport->custom_divisor = new_serial.custom_divisor;

		goto check_and_exit;

	}



	/*

	 * Ask the low level driver to verify the settings.

	 */

	if (port->ops->verify_port)

		retval = port->ops->verify_port(port, &new_serial);

	if (uport->ops->verify_port)

		retval = uport->ops->verify_port(uport, &new_serial);



	if ((new_serial.irq >= nr_irqs) || (new_serial.irq < 0) ||

	    (new_serial.baud_base < 9600))
@@ -769,31 +771,31 @@ static int uart_set_info(struct uart_state *state, 
		unsigned long old_iobase, old_mapbase;

		unsigned int old_type, old_iotype, old_hub6, old_shift;



		old_iobase = port->iobase;

		old_mapbase = port->mapbase;

		old_type = port->type;

		old_hub6 = port->hub6;

		old_iotype = port->iotype;

		old_shift = port->regshift;

		old_iobase = uport->iobase;

		old_mapbase = uport->mapbase;

		old_type = uport->type;

		old_hub6 = uport->hub6;

		old_iotype = uport->iotype;

		old_shift = uport->regshift;



		/*

		 * Free and release old regions

		 */

		if (old_type != PORT_UNKNOWN)

			port->ops->release_port(port);

			uport->ops->release_port(uport);



		port->iobase = new_port;

		port->type = new_serial.type;

		port->hub6 = new_serial.hub6;

		port->iotype = new_serial.io_type;

		port->regshift = new_serial.iomem_reg_shift;

		port->mapbase = (unsigned long)new_serial.iomem_base;

		uport->iobase = new_port;

		uport->type = new_serial.type;

		uport->hub6 = new_serial.hub6;

		uport->iotype = new_serial.io_type;

		uport->regshift = new_serial.iomem_reg_shift;

		uport->mapbase = (unsigned long)new_serial.iomem_base;



		/*

		 * Claim and map the new regions

		 */

		if (port->type != PORT_UNKNOWN) {

			retval = port->ops->request_port(port);

		if (uport->type != PORT_UNKNOWN) {

			retval = uport->ops->request_port(uport);

		} else {

			/* Always success - Jean II */

			retval = 0;
@@ -804,19 +806,19 @@ static int uart_set_info(struct uart_state *state, 
		 * new port, try to restore the old settings.

		 */

		if (retval && old_type != PORT_UNKNOWN) {

			port->iobase = old_iobase;

			port->type = old_type;

			port->hub6 = old_hub6;

			port->iotype = old_iotype;

			port->regshift = old_shift;

			port->mapbase = old_mapbase;

			retval = port->ops->request_port(port);

			uport->iobase = old_iobase;

			uport->type = old_type;

			uport->hub6 = old_hub6;

			uport->iotype = old_iotype;

			uport->regshift = old_shift;

			uport->mapbase = old_mapbase;

			retval = uport->ops->request_port(uport);

			/*

			 * If we failed to restore the old settings,

			 * we fail like this.

			 */

			if (retval)

				port->type = PORT_UNKNOWN;

				uport->type = PORT_UNKNOWN;



			/*

			 * We failed anyway.
@@ -828,38 +830,38 @@ static int uart_set_info(struct uart_state *state, 
	}



	if (change_irq)

		port->irq      = new_serial.irq;

	if (!(port->flags & UPF_FIXED_PORT))

		port->uartclk  = new_serial.baud_base * 16;

	port->flags            = (port->flags & ~UPF_CHANGE_MASK) |

		uport->irq      = new_serial.irq;

	if (!(uport->flags & UPF_FIXED_PORT))

		uport->uartclk  = new_serial.baud_base * 16;

	uport->flags            = (uport->flags & ~UPF_CHANGE_MASK) |

				 (new_flags & UPF_CHANGE_MASK);

	port->custom_divisor   = new_serial.custom_divisor;

	state->port.close_delay     = close_delay;

	state->port.closing_wait    = closing_wait;

	uport->custom_divisor   = new_serial.custom_divisor;

	port->close_delay     = close_delay;

	port->closing_wait    = closing_wait;

	if (new_serial.xmit_fifo_size)

		port->fifosize = new_serial.xmit_fifo_size;

	if (state->port.tty)

		state->port.tty->low_latency =

			(port->flags & UPF_LOW_LATENCY) ? 1 : 0;

		uport->fifosize = new_serial.xmit_fifo_size;

	if (port->tty)

		port->tty->low_latency =

			(uport->flags & UPF_LOW_LATENCY) ? 1 : 0;



 check_and_exit:

	retval = 0;

	if (port->type == PORT_UNKNOWN)

	if (uport->type == PORT_UNKNOWN)

		goto exit;

	if (state->flags & UIF_INITIALIZED) {

		if (((old_flags ^ port->flags) & UPF_SPD_MASK) ||

		    old_custom_divisor != port->custom_divisor) {

		if (((old_flags ^ uport->flags) & UPF_SPD_MASK) ||

		    old_custom_divisor != uport->custom_divisor) {

			/*

			 * If they're setting up a custom divisor or speed,

			 * instead of clearing it, then bitch about it. No

			 * need to rate-limit; it's CAP_SYS_ADMIN only.

			 */

			if (port->flags & UPF_SPD_MASK) {

			if (uport->flags & UPF_SPD_MASK) {

				char buf[64];

				printk(KERN_NOTICE

				       "%s sets custom speed on %s. This "

				       "is deprecated.\n", current->comm,

				       tty_name(state->port.tty, buf));

				       tty_name(port->tty, buf));

			}

			uart_change_speed(state, NULL);

		}
@@ -878,10 +880,11 @@ static int uart_set_info(struct uart_state *state, 
static int uart_get_lsr_info(struct uart_state *state,

			     unsigned int __user *value)

{

	struct uart_port *port = state->uart_port;

	struct uart_port *uport = state->uart_port;

	struct tty_port *port = &state->port;

	unsigned int result;



	result = port->ops->tx_empty(port);

	result = uport->ops->tx_empty(uport);



	/*

	 * If we're about to load something into the transmit
@@ -889,9 +892,9 @@ static int uart_get_lsr_info(struct uart_state *state, 
	 * avoid a race condition (depending on when the transmit

	 * interrupt happens).

	 */

	if (port->x_char ||

	if (uport->x_char ||

	    ((uart_circ_chars_pending(&state->xmit) > 0) &&

	     !state->port.tty->stopped && !state->port.tty->hw_stopped))

	     !port->tty->stopped && !port->tty->hw_stopped))

		result &= ~TIOCSER_TEMT;



	return put_user(result, value);
@@ -900,17 +903,17 @@ static int uart_get_lsr_info(struct uart_state *state, 
static int uart_tiocmget(struct tty_struct *tty, struct file *file)

{

	struct uart_state *state = tty->driver_data;

	struct uart_port *port = state->uart_port;

	struct uart_port *uport = state->uart_port;

	int result = -EIO;



	mutex_lock(&state->mutex);

	if ((!file || !tty_hung_up_p(file)) &&

	    !(tty->flags & (1 << TTY_IO_ERROR))) {

		result = port->mctrl;

		result = uport->mctrl;



		spin_lock_irq(&port->lock);

		result |= port->ops->get_mctrl(port);

		spin_unlock_irq(&port->lock);

		spin_lock_irq(&uport->lock);

		result |= uport->ops->get_mctrl(uport);

		spin_unlock_irq(&uport->lock);

	}

	mutex_unlock(&state->mutex);
@@ -922,13 +925,13 @@ uart_tiocmset(struct tty_struct *tty, struct file *file, 
	      unsigned int set, unsigned int clear)

{

	struct uart_state *state = tty->driver_data;

	struct uart_port *port = state->uart_port;

	struct uart_port *uport = state->uart_port;

	int ret = -EIO;



	mutex_lock(&state->mutex);

	if ((!file || !tty_hung_up_p(file)) &&

	    !(tty->flags & (1 << TTY_IO_ERROR))) {

		uart_update_mctrl(port, set, clear);

		uart_update_mctrl(uport, set, clear);

		ret = 0;

	}

	mutex_unlock(&state->mutex);
@@ -938,12 +941,12 @@ uart_tiocmset(struct tty_struct *tty, struct file *file, 
static int uart_break_ctl(struct tty_struct *tty, int break_state)

{

	struct uart_state *state = tty->driver_data;

	struct uart_port *port = state->uart_port;

	struct uart_port *uport = state->uart_port;



	mutex_lock(&state->mutex);



	if (port->type != PORT_UNKNOWN)

		port->ops->break_ctl(port, break_state);

	if (uport->type != PORT_UNKNOWN)

		uport->ops->break_ctl(uport, break_state);



	mutex_unlock(&state->mutex);

	return 0;
@@ -951,7 +954,7 @@ static int uart_break_ctl(struct tty_struct *tty, int break_state) 


static int uart_do_autoconfig(struct uart_state *state)

{

	struct uart_port *port = state->uart_port;

	struct uart_port *uport = state->uart_port;

	int flags, ret;



	if (!capable(CAP_SYS_ADMIN))
@@ -973,18 +976,18 @@ static int uart_do_autoconfig(struct uart_state *state) 
		 * If we already have a port type configured,

		 * we must release its resources.

		 */

		if (port->type != PORT_UNKNOWN)

			port->ops->release_port(port);

		if (uport->type != PORT_UNKNOWN)

			uport->ops->release_port(uport);



		flags = UART_CONFIG_TYPE;

		if (port->flags & UPF_AUTO_IRQ)

		if (uport->flags & UPF_AUTO_IRQ)

			flags |= UART_CONFIG_IRQ;



		/*

		 * This will claim the ports resources if

		 * a port is found.

		 */

		port->ops->config_port(port, flags);

		uport->ops->config_port(uport, flags);



		ret = uart_startup(state, 1);

	}
@@ -1001,7 +1004,7 @@ static int uart_do_autoconfig(struct uart_state *state) 
static int

uart_wait_modem_status(struct uart_state *state, unsigned long arg)

{

	struct uart_port *port = state->uart_port;

	struct uart_port *uport = state->uart_port;

	DECLARE_WAITQUEUE(wait, current);

	struct uart_icount cprev, cnow;

	int ret;
@@ -1009,20 +1012,20 @@ uart_wait_modem_status(struct uart_state *state, unsigned long arg) 
	/*

	 * note the counters on entry

	 */

	spin_lock_irq(&port->lock);

	memcpy(&cprev, &port->icount, sizeof(struct uart_icount));

	spin_lock_irq(&uport->lock);

	memcpy(&cprev, &uport->icount, sizeof(struct uart_icount));



	/*

	 * Force modem status interrupts on

	 */

	port->ops->enable_ms(port);

	spin_unlock_irq(&port->lock);

	uport->ops->enable_ms(uport);

	spin_unlock_irq(&uport->lock);



	add_wait_queue(&state->delta_msr_wait, &wait);

	for (;;) {

		spin_lock_irq(&port->lock);

		memcpy(&cnow, &port->icount, sizeof(struct uart_icount));

		spin_unlock_irq(&port->lock);

		spin_lock_irq(&uport->lock);

		memcpy(&cnow, &uport->icount, sizeof(struct uart_icount));

		spin_unlock_irq(&uport->lock);



		set_current_state(TASK_INTERRUPTIBLE);
@@ -1062,11 +1065,11 @@ static int uart_get_count(struct uart_state *state, 
{

	struct serial_icounter_struct icount;

	struct uart_icount cnow;

	struct uart_port *port = state->uart_port;

	struct uart_port *uport = state->uart_port;



	spin_lock_irq(&port->lock);

	memcpy(&cnow, &port->icount, sizeof(struct uart_icount));

	spin_unlock_irq(&port->lock);

	spin_lock_irq(&uport->lock);

	memcpy(&cnow, &uport->icount, sizeof(struct uart_icount));

	spin_unlock_irq(&uport->lock);



	icount.cts         = cnow.cts;

	icount.dsr         = cnow.dsr;
@@ -1158,9 +1161,9 @@ uart_ioctl(struct tty_struct *tty, struct file *filp, unsigned int cmd, 
		break;



	default: {

		struct uart_port *port = state->uart_port;

		if (port->ops->ioctl)

			ret = port->ops->ioctl(port, cmd, arg);

		struct uart_port *uport = state->uart_port;

		if (uport->ops->ioctl)

			ret = uport->ops->ioctl(uport, cmd, arg);

		break;

	}

	}
@@ -1173,10 +1176,10 @@ uart_ioctl(struct tty_struct *tty, struct file *filp, unsigned int cmd, 
static void uart_set_ldisc(struct tty_struct *tty)

{

	struct uart_state *state = tty->driver_data;

	struct uart_port *port = state->uart_port;

	struct uart_port *uport = state->uart_port;



	if (port->ops->set_ldisc)

		port->ops->set_ldisc(port);

	if (uport->ops->set_ldisc)

		uport->ops->set_ldisc(uport);

}



static void uart_set_termios(struct tty_struct *tty,
@@ -1254,16 +1257,15 @@ static void uart_set_termios(struct tty_struct *tty, 
static void uart_close(struct tty_struct *tty, struct file *filp)

{

	struct uart_state *state = tty->driver_data;

	struct uart_port *port;

	struct tty_port *port;

	struct uart_port *uport;



	BUG_ON(!kernel_locked());



	if (!state || !state->uart_port)

		return;

	uport = state->uart_port;

	port = &state->port;



	port = state->uart_port;



	pr_debug("uart_close(%d) called\n", port->line);

	pr_debug("uart_close(%d) called\n", uport->line);



	mutex_lock(&state->mutex);
@@ -1297,8 +1299,8 @@ static void uart_close(struct tty_struct *tty, struct file *filp) 
	 */

	tty->closing = 1;



	if (state->port.closing_wait != USF_CLOSING_WAIT_NONE)

		tty_wait_until_sent(tty, msecs_to_jiffies(state->port.closing_wait));

	if (port->closing_wait != USF_CLOSING_WAIT_NONE)

		tty_wait_until_sent(tty, msecs_to_jiffies(port->closing_wait));



	/*

	 * At this point, we stop accepting input.  To do this, we
@@ -1307,14 +1309,14 @@ static void uart_close(struct tty_struct *tty, struct file *filp) 
	if (state->flags & UIF_INITIALIZED) {

		unsigned long flags;

		spin_lock_irqsave(&port->lock, flags);

		port->ops->stop_rx(port);

		uport->ops->stop_rx(uport);

		spin_unlock_irqrestore(&port->lock, flags);

		/*

		 * Before we drop DTR, make sure the UART transmitter

		 * has completely drained; this is especially

		 * important if there is a transmit FIFO!

		 */

		uart_wait_until_sent(tty, port->timeout);

		uart_wait_until_sent(tty, uport->timeout);

	}



	uart_shutdown(state);
@@ -1323,12 +1325,12 @@ static void uart_close(struct tty_struct *tty, struct file *filp) 
	tty_ldisc_flush(tty);



	tty->closing = 0;

	state->port.tty = NULL;

	port->tty = NULL;



	if (state->port.blocked_open) {

		if (state->port.close_delay)

			msleep_interruptible(state->port.close_delay);

	} else if (!uart_console(port)) {

	if (port->blocked_open) {

		if (port->close_delay)

			msleep_interruptible(port->close_delay);

	} else if (!uart_console(uport)) {

		uart_change_pm(state, 3);

	}
@@ -1336,7 +1338,7 @@ static void uart_close(struct tty_struct *tty, struct file *filp) 
	 * Wake up anyone trying to open this port.

	 */

	state->flags &= ~UIF_NORMAL_ACTIVE;

	wake_up_interruptible(&state->port.open_wait);

	wake_up_interruptible(&port->open_wait);



done:

	mutex_unlock(&state->mutex);
@@ -1410,6 +1412,7 @@ static void uart_wait_until_sent(struct tty_struct *tty, int timeout) 
static void uart_hangup(struct tty_struct *tty)

{

	struct uart_state *state = tty->driver_data;

	struct tty_port *port = &state->port;



	BUG_ON(!kernel_locked());

	pr_debug("uart_hangup(%d)\n", state->uart_port->line);
@@ -1420,8 +1423,8 @@ static void uart_hangup(struct tty_struct *tty) 
		uart_shutdown(state);

		state->count = 0;

		state->flags &= ~UIF_NORMAL_ACTIVE;

		state->port.tty = NULL;

		wake_up_interruptible(&state->port.open_wait);

		port->tty = NULL;

		wake_up_interruptible(&port->open_wait);

		wake_up_interruptible(&state->delta_msr_wait);

	}

	mutex_unlock(&state->mutex);
@@ -1470,20 +1473,21 @@ static int 
uart_block_til_ready(struct file *filp, struct uart_state *state)

{

	DECLARE_WAITQUEUE(wait, current);

	struct uart_port *port = state->uart_port;

	struct uart_port *uport = state->uart_port;

	struct tty_port *port = &state->port;

	unsigned int mctrl;



	state->port.blocked_open++;

	port->blocked_open++;

	state->count--;



	add_wait_queue(&state->port.open_wait, &wait);

	add_wait_queue(&port->open_wait, &wait);

	while (1) {

		set_current_state(TASK_INTERRUPTIBLE);



		/*

		 * If we have been hung up, tell userspace/restart open.

		 */

		if (tty_hung_up_p(filp) || state->port.tty == NULL)

		if (tty_hung_up_p(filp) || port->tty == NULL)

			break;



		/*
@@ -1502,8 +1506,8 @@ uart_block_til_ready(struct file *filp, struct uart_state *state) 
		 * have set TTY_IO_ERROR for a non-existant port.

		 */

		if ((filp->f_flags & O_NONBLOCK) ||

		    (state->port.tty->termios->c_cflag & CLOCAL) ||

		    (state->port.tty->flags & (1 << TTY_IO_ERROR)))

		    (port->tty->termios->c_cflag & CLOCAL) ||

		    (port->tty->flags & (1 << TTY_IO_ERROR)))

			break;



		/*
@@ -1511,17 +1515,17 @@ uart_block_til_ready(struct file *filp, struct uart_state *state) 
		 * not set RTS here - we want to make sure we catch

		 * the data from the modem.

		 */

		if (state->port.tty->termios->c_cflag & CBAUD)

			uart_set_mctrl(port, TIOCM_DTR);

		if (port->tty->termios->c_cflag & CBAUD)

			uart_set_mctrl(uport, TIOCM_DTR);



		/*

		 * and wait for the carrier to indicate that the

		 * modem is ready for us.

		 */

		spin_lock_irq(&port->lock);

		port->ops->enable_ms(port);

		mctrl = port->ops->get_mctrl(port);

		spin_unlock_irq(&port->lock);

		spin_lock_irq(&uport->lock);

		uport->ops->enable_ms(uport);

		mctrl = uport->ops->get_mctrl(uport);

		spin_unlock_irq(&uport->lock);

		if (mctrl & TIOCM_CAR)

			break;
@@ -1533,15 +1537,15 @@ uart_block_til_ready(struct file *filp, struct uart_state *state) 
			break;

	}

	set_current_state(TASK_RUNNING);

	remove_wait_queue(&state->port.open_wait, &wait);

	remove_wait_queue(&port->open_wait, &wait);



	state->count++;

	state->port.blocked_open--;

	port->blocked_open--;



	if (signal_pending(current))

		return -ERESTARTSYS;



	if (!state->port.tty || tty_hung_up_p(filp))

	if (!port->tty || tty_hung_up_p(filp))

		return -EAGAIN;



	return 0;