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32 results

serial_core.c

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  • serial_core.c 61.61 KiB
    /*
     *  linux/drivers/char/core.c
     *
     *  Driver core for serial ports
     *
     *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
     *
     *  Copyright 1999 ARM Limited
     *  Copyright (C) 2000-2001 Deep Blue Solutions Ltd.
     *
     * This program is free software; you can redistribute it and/or modify
     * it under the terms of the GNU General Public License as published by
     * the Free Software Foundation; either version 2 of the License, or
     * (at your option) any later version.
     *
     * This program is distributed in the hope that it will be useful,
     * but WITHOUT ANY WARRANTY; without even the implied warranty of
     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     * GNU General Public License for more details.
     *
     * You should have received a copy of the GNU General Public License
     * along with this program; if not, write to the Free Software
     * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
     */
    #include <linux/module.h>
    #include <linux/tty.h>
    #include <linux/slab.h>
    #include <linux/init.h>
    #include <linux/console.h>
    #include <linux/serial_core.h>
    #include <linux/smp_lock.h>
    #include <linux/device.h>
    #include <linux/serial.h> /* for serial_state and serial_icounter_struct */
    #include <linux/delay.h>
    #include <linux/mutex.h>
    
    #include <asm/irq.h>
    #include <asm/uaccess.h>
    
    /*
     * This is used to lock changes in serial line configuration.
     */
    static DEFINE_MUTEX(port_mutex);
    
    /*
     * lockdep: port->lock is initialized in two places, but we
     *          want only one lock-class:
     */
    static struct lock_class_key port_lock_key;
    
    #define HIGH_BITS_OFFSET	((sizeof(long)-sizeof(int))*8)
    
    #define uart_users(state)	((state)->count + ((state)->info ? (state)->info->blocked_open : 0))
    
    #ifdef CONFIG_SERIAL_CORE_CONSOLE
    #define uart_console(port)	((port)->cons && (port)->cons->index == (port)->line)
    #else
    #define uart_console(port)	(0)
    #endif
    
    static void uart_change_speed(struct uart_state *state,
    					struct ktermios *old_termios);
    static void uart_wait_until_sent(struct tty_struct *tty, int timeout);
    static void uart_change_pm(struct uart_state *state, int pm_state);
    
    /*
     * This routine is used by the interrupt handler to schedule processing in
     * the software interrupt portion of the driver.
     */
    void uart_write_wakeup(struct uart_port *port)
    {
    	struct uart_info *info = port->info;
    	/*
    	 * This means you called this function _after_ the port was
    	 * closed.  No cookie for you.
    	 */
    	BUG_ON(!info);
    	tasklet_schedule(&info->tlet);
    }
    
    static void uart_stop(struct tty_struct *tty)
    {
    	struct uart_state *state = tty->driver_data;
    	struct uart_port *port = state->port;
    	unsigned long flags;
    
    	spin_lock_irqsave(&port->lock, flags);
    	port->ops->stop_tx(port);
    	spin_unlock_irqrestore(&port->lock, flags);
    }
    
    static void __uart_start(struct tty_struct *tty)
    {
    	struct uart_state *state = tty->driver_data;
    	struct uart_port *port = state->port;
    
    	if (!uart_circ_empty(&state->info->xmit) && state->info->xmit.buf &&
    	    !tty->stopped && !tty->hw_stopped)
    		port->ops->start_tx(port);
    }
    
    static void uart_start(struct tty_struct *tty)
    {
    	struct uart_state *state = tty->driver_data;
    	struct uart_port *port = state->port;
    	unsigned long flags;
    
    	spin_lock_irqsave(&port->lock, flags);
    	__uart_start(tty);
    	spin_unlock_irqrestore(&port->lock, flags);
    }
    
    static void uart_tasklet_action(unsigned long data)
    {
    	struct uart_state *state = (struct uart_state *)data;
    	tty_wakeup(state->info->tty);
    }
    
    static inline void
    uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear)
    {
    	unsigned long flags;
    	unsigned int old;
    
    	spin_lock_irqsave(&port->lock, flags);
    	old = port->mctrl;
    	port->mctrl = (old & ~clear) | set;
    	if (old != port->mctrl)
    		port->ops->set_mctrl(port, port->mctrl);
    	spin_unlock_irqrestore(&port->lock, flags);
    }
    
    #define uart_set_mctrl(port, set)	uart_update_mctrl(port, set, 0)
    #define uart_clear_mctrl(port, clear)	uart_update_mctrl(port, 0, clear)
    
    /*
     * Startup the port.  This will be called once per open.  All calls
     * will be serialised by the per-port semaphore.
     */
    static int uart_startup(struct uart_state *state, int init_hw)
    {
    	struct uart_info *info = state->info;
    	struct uart_port *port = state->port;
    	unsigned long page;
    	int retval = 0;
    
    	if (info->flags & UIF_INITIALIZED)
    		return 0;
    
    	/*
    	 * Set the TTY IO error marker - we will only clear this
    	 * once we have successfully opened the port.  Also set
    	 * up the tty->alt_speed kludge
    	 */
    	set_bit(TTY_IO_ERROR, &info->tty->flags);
    
    	if (port->type == PORT_UNKNOWN)
    		return 0;
    
    	/*
    	 * Initialise and allocate the transmit and temporary
    	 * buffer.
    	 */
    	if (!info->xmit.buf) {
    		page = get_zeroed_page(GFP_KERNEL);
    		if (!page)
    			return -ENOMEM;
    
    		info->xmit.buf = (unsigned char *) page;
    		uart_circ_clear(&info->xmit);
    	}
    
    	retval = port->ops->startup(port);
    	if (retval == 0) {
    		if (init_hw) {
    			/*
    			 * Initialise the hardware port settings.
    			 */
    			uart_change_speed(state, NULL);
    
    			/*
    			 * Setup the RTS and DTR signals once the
    			 * port is open and ready to respond.
    			 */
    			if (info->tty->termios->c_cflag & CBAUD)
    				uart_set_mctrl(port, TIOCM_RTS | TIOCM_DTR);
    		}
    
    		if (info->flags & UIF_CTS_FLOW) {
    			spin_lock_irq(&port->lock);
    			if (!(port->ops->get_mctrl(port) & TIOCM_CTS))
    				info->tty->hw_stopped = 1;
    			spin_unlock_irq(&port->lock);
    		}
    
    		info->flags |= UIF_INITIALIZED;
    
    		clear_bit(TTY_IO_ERROR, &info->tty->flags);
    	}
    
    	if (retval && capable(CAP_SYS_ADMIN))
    		retval = 0;
    
    	return retval;
    }
    
    /*
     * This routine will shutdown a serial port; interrupts are disabled, and
     * DTR is dropped if the hangup on close termio flag is on.  Calls to
     * uart_shutdown are serialised by the per-port semaphore.
     */
    static void uart_shutdown(struct uart_state *state)
    {
    	struct uart_info *info = state->info;
    	struct uart_port *port = state->port;
    
    	/*
    	 * Set the TTY IO error marker
    	 */
    	if (info->tty)
    		set_bit(TTY_IO_ERROR, &info->tty->flags);
    
    	if (info->flags & UIF_INITIALIZED) {
    		info->flags &= ~UIF_INITIALIZED;
    
    		/*
    		 * Turn off DTR and RTS early.
    		 */
    		if (!info->tty || (info->tty->termios->c_cflag & HUPCL))
    			uart_clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);
    
    		/*
    		 * clear delta_msr_wait queue to avoid mem leaks: we may free
    		 * the irq here so the queue might never be woken up.  Note
    		 * that we won't end up waiting on delta_msr_wait again since
    		 * any outstanding file descriptors should be pointing at
    		 * hung_up_tty_fops now.
    		 */
    		wake_up_interruptible(&info->delta_msr_wait);
    
    		/*
    		 * Free the IRQ and disable the port.
    		 */
    		port->ops->shutdown(port);
    
    		/*
    		 * Ensure that the IRQ handler isn't running on another CPU.
    		 */
    		synchronize_irq(port->irq);
    	}
    
    	/*
    	 * kill off our tasklet
    	 */
    	tasklet_kill(&info->tlet);
    
    	/*
    	 * Free the transmit buffer page.
    	 */
    	if (info->xmit.buf) {
    		free_page((unsigned long)info->xmit.buf);
    		info->xmit.buf = NULL;
    	}
    }
    
    /**
     *	uart_update_timeout - update per-port FIFO timeout.
     *	@port:  uart_port structure describing the port
     *	@cflag: termios cflag value
     *	@baud:  speed of the port
     *
     *	Set the port FIFO timeout value.  The @cflag value should
     *	reflect the actual hardware settings.
     */
    void
    uart_update_timeout(struct uart_port *port, unsigned int cflag,
    		    unsigned int baud)
    {
    	unsigned int bits;
    
    	/* byte size and parity */
    	switch (cflag & CSIZE) {
    	case CS5:
    		bits = 7;
    		break;
    	case CS6:
    		bits = 8;
    		break;
    	case CS7:
    		bits = 9;
    		break;
    	default:
    		bits = 10;
    		break; /* CS8 */
    	}
    
    	if (cflag & CSTOPB)
    		bits++;
    	if (cflag & PARENB)
    		bits++;
    
    	/*
    	 * The total number of bits to be transmitted in the fifo.
    	 */
    	bits = bits * port->fifosize;
    
    	/*
    	 * Figure the timeout to send the above number of bits.
    	 * Add .02 seconds of slop
    	 */
    	port->timeout = (HZ * bits) / baud + HZ/50;
    }
    
    EXPORT_SYMBOL(uart_update_timeout);
    
    /**
     *	uart_get_baud_rate - return baud rate for a particular port
     *	@port: uart_port structure describing the port in question.
     *	@termios: desired termios settings.
     *	@old: old termios (or NULL)
     *	@min: minimum acceptable baud rate
     *	@max: maximum acceptable baud rate
     *
     *	Decode the termios structure into a numeric baud rate,
     *	taking account of the magic 38400 baud rate (with spd_*
     *	flags), and mapping the %B0 rate to 9600 baud.
     *
     *	If the new baud rate is invalid, try the old termios setting.
     *	If it's still invalid, we try 9600 baud.
     *
     *	Update the @termios structure to reflect the baud rate
     *	we're actually going to be using. Don't do this for the case
     *	where B0 is requested ("hang up").
     */
    unsigned int
    uart_get_baud_rate(struct uart_port *port, struct ktermios *termios,
    		   struct ktermios *old, unsigned int min, unsigned int max)
    {
    	unsigned int try, baud, altbaud = 38400;
    	int hung_up = 0;
    	upf_t flags = port->flags & UPF_SPD_MASK;
    
    	if (flags == UPF_SPD_HI)
    		altbaud = 57600;
    	if (flags == UPF_SPD_VHI)
    		altbaud = 115200;
    	if (flags == UPF_SPD_SHI)
    		altbaud = 230400;
    	if (flags == UPF_SPD_WARP)
    		altbaud = 460800;
    
    	for (try = 0; try < 2; try++) {
    		baud = tty_termios_baud_rate(termios);
    
    		/*
    		 * The spd_hi, spd_vhi, spd_shi, spd_warp kludge...
    		 * Die! Die! Die!
    		 */
    		if (baud == 38400)
    			baud = altbaud;
    
    		/*
    		 * Special case: B0 rate.
    		 */
    		if (baud == 0) {
    			hung_up = 1;
    			baud = 9600;
    		}
    
    		if (baud >= min && baud <= max)
    			return baud;
    
    		/*
    		 * Oops, the quotient was zero.  Try again with
    		 * the old baud rate if possible.
    		 */
    		termios->c_cflag &= ~CBAUD;
    		if (old) {
    			baud = tty_termios_baud_rate(old);
    			if (!hung_up)
    				tty_termios_encode_baud_rate(termios,
    								baud, baud);
    			old = NULL;
    			continue;
    		}
    
    		/*
    		 * As a last resort, if the quotient is zero,
    		 * default to 9600 bps
    		 */
    		if (!hung_up)
    			tty_termios_encode_baud_rate(termios, 9600, 9600);
    	}
    
    	return 0;
    }
    
    EXPORT_SYMBOL(uart_get_baud_rate);
    
    /**
     *	uart_get_divisor - return uart clock divisor
     *	@port: uart_port structure describing the port.
     *	@baud: desired baud rate
     *
     *	Calculate the uart clock divisor for the port.
     */
    unsigned int
    uart_get_divisor(struct uart_port *port, unsigned int baud)
    {
    	unsigned int quot;
    
    	/*
    	 * Old custom speed handling.
    	 */
    	if (baud == 38400 && (port->flags & UPF_SPD_MASK) == UPF_SPD_CUST)
    		quot = port->custom_divisor;
    	else
    		quot = (port->uartclk + (8 * baud)) / (16 * baud);
    
    	return quot;
    }
    
    EXPORT_SYMBOL(uart_get_divisor);
    
    static void
    uart_change_speed(struct uart_state *state, struct ktermios *old_termios)
    {
    	struct tty_struct *tty = state->info->tty;
    	struct uart_port *port = state->port;
    	struct ktermios *termios;
    
    	/*
    	 * If we have no tty, termios, or the port does not exist,
    	 * then we can't set the parameters for this port.
    	 */
    	if (!tty || !tty->termios || port->type == PORT_UNKNOWN)
    		return;
    
    	termios = tty->termios;
    
    	/*
    	 * Set flags based on termios cflag
    	 */
    	if (termios->c_cflag & CRTSCTS)
    		state->info->flags |= UIF_CTS_FLOW;
    	else
    		state->info->flags &= ~UIF_CTS_FLOW;
    
    	if (termios->c_cflag & CLOCAL)
    		state->info->flags &= ~UIF_CHECK_CD;
    	else
    		state->info->flags |= UIF_CHECK_CD;
    
    	port->ops->set_termios(port, termios, old_termios);
    }
    
    static inline void
    __uart_put_char(struct uart_port *port, struct circ_buf *circ, unsigned char c)
    {
    	unsigned long flags;
    
    	if (!circ->buf)
    		return;
    
    	spin_lock_irqsave(&port->lock, flags);
    	if (uart_circ_chars_free(circ) != 0) {
    		circ->buf[circ->head] = c;
    		circ->head = (circ->head + 1) & (UART_XMIT_SIZE - 1);
    	}
    	spin_unlock_irqrestore(&port->lock, flags);
    }
    
    static void uart_put_char(struct tty_struct *tty, unsigned char ch)
    {
    	struct uart_state *state = tty->driver_data;
    
    	__uart_put_char(state->port, &state->info->xmit, ch);
    }
    
    static void uart_flush_chars(struct tty_struct *tty)
    {
    	uart_start(tty);
    }
    
    static int
    uart_write(struct tty_struct *tty, const unsigned char *buf, int count)
    {
    	struct uart_state *state = tty->driver_data;
    	struct uart_port *port;
    	struct circ_buf *circ;
    	unsigned long flags;
    	int c, ret = 0;
    
    	/*
    	 * This means you called this function _after_ the port was
    	 * closed.  No cookie for you.
    	 */
    	if (!state || !state->info) {
    		WARN_ON(1);
    		return -EL3HLT;
    	}
    
    	port = state->port;
    	circ = &state->info->xmit;
    
    	if (!circ->buf)
    		return 0;
    
    	spin_lock_irqsave(&port->lock, flags);
    	while (1) {
    		c = CIRC_SPACE_TO_END(circ->head, circ->tail, UART_XMIT_SIZE);
    		if (count < c)
    			c = count;
    		if (c <= 0)
    			break;
    		memcpy(circ->buf + circ->head, buf, c);
    		circ->head = (circ->head + c) & (UART_XMIT_SIZE - 1);
    		buf += c;
    		count -= c;
    		ret += c;
    	}
    	spin_unlock_irqrestore(&port->lock, flags);
    
    	uart_start(tty);
    	return ret;
    }
    
    static int uart_write_room(struct tty_struct *tty)
    {
    	struct uart_state *state = tty->driver_data;
    
    	return uart_circ_chars_free(&state->info->xmit);
    }
    
    static int uart_chars_in_buffer(struct tty_struct *tty)
    {
    	struct uart_state *state = tty->driver_data;
    
    	return uart_circ_chars_pending(&state->info->xmit);
    }
    
    static void uart_flush_buffer(struct tty_struct *tty)
    {
    	struct uart_state *state = tty->driver_data;
    	struct uart_port *port = state->port;
    	unsigned long flags;
    
    	/*
    	 * This means you called this function _after_ the port was
    	 * closed.  No cookie for you.
    	 */
    	if (!state || !state->info) {
    		WARN_ON(1);
    		return;
    	}
    
    	pr_debug("uart_flush_buffer(%d) called\n", tty->index);
    
    	spin_lock_irqsave(&port->lock, flags);
    	uart_circ_clear(&state->info->xmit);
    	spin_unlock_irqrestore(&port->lock, flags);
    	tty_wakeup(tty);
    }
    
    /*
     * This function is used to send a high-priority XON/XOFF character to
     * the device
     */
    static void uart_send_xchar(struct tty_struct *tty, char ch)
    {
    	struct uart_state *state = tty->driver_data;
    	struct uart_port *port = state->port;
    	unsigned long flags;
    
    	if (port->ops->send_xchar)
    		port->ops->send_xchar(port, ch);
    	else {
    		port->x_char = ch;
    		if (ch) {
    			spin_lock_irqsave(&port->lock, flags);
    			port->ops->start_tx(port);
    			spin_unlock_irqrestore(&port->lock, flags);
    		}
    	}
    }
    
    static void uart_throttle(struct tty_struct *tty)
    {
    	struct uart_state *state = tty->driver_data;
    
    	if (I_IXOFF(tty))
    		uart_send_xchar(tty, STOP_CHAR(tty));
    
    	if (tty->termios->c_cflag & CRTSCTS)
    		uart_clear_mctrl(state->port, TIOCM_RTS);
    }
    
    static void uart_unthrottle(struct tty_struct *tty)
    {
    	struct uart_state *state = tty->driver_data;
    	struct uart_port *port = state->port;
    
    	if (I_IXOFF(tty)) {
    		if (port->x_char)
    			port->x_char = 0;
    		else
    			uart_send_xchar(tty, START_CHAR(tty));
    	}
    
    	if (tty->termios->c_cflag & CRTSCTS)
    		uart_set_mctrl(port, TIOCM_RTS);
    }
    
    static int uart_get_info(struct uart_state *state,
    			 struct serial_struct __user *retinfo)
    {
    	struct uart_port *port = state->port;
    	struct serial_struct tmp;
    
    	memset(&tmp, 0, sizeof(tmp));
    	tmp.type	    = port->type;
    	tmp.line	    = port->line;
    	tmp.port	    = port->iobase;
    	if (HIGH_BITS_OFFSET)
    		tmp.port_high = (long) port->iobase >> HIGH_BITS_OFFSET;
    	tmp.irq		    = port->irq;
    	tmp.flags	    = port->flags;
    	tmp.xmit_fifo_size  = port->fifosize;
    	tmp.baud_base	    = port->uartclk / 16;
    	tmp.close_delay	    = state->close_delay / 10;
    	tmp.closing_wait    = state->closing_wait == USF_CLOSING_WAIT_NONE ?
    				ASYNC_CLOSING_WAIT_NONE :
    				state->closing_wait / 10;
    	tmp.custom_divisor  = port->custom_divisor;
    	tmp.hub6	    = port->hub6;
    	tmp.io_type         = port->iotype;
    	tmp.iomem_reg_shift = port->regshift;
    	tmp.iomem_base      = (void *)(unsigned long)port->mapbase;
    
    	if (copy_to_user(retinfo, &tmp, sizeof(*retinfo)))
    		return -EFAULT;
    	return 0;
    }
    
    static int uart_set_info(struct uart_state *state,
    			 struct serial_struct __user *newinfo)
    {
    	struct serial_struct new_serial;
    	struct uart_port *port = state->port;
    	unsigned long new_port;
    	unsigned int change_irq, change_port, closing_wait;
    	unsigned int old_custom_divisor, close_delay;
    	upf_t old_flags, new_flags;
    	int retval = 0;
    
    	if (copy_from_user(&new_serial, newinfo, sizeof(new_serial)))
    		return -EFAULT;
    
    	new_port = new_serial.port;
    	if (HIGH_BITS_OFFSET)
    		new_port += (unsigned long) new_serial.port_high << HIGH_BITS_OFFSET;
    
    	new_serial.irq = irq_canonicalize(new_serial.irq);
    	close_delay = new_serial.close_delay * 10;
    	closing_wait = new_serial.closing_wait == ASYNC_CLOSING_WAIT_NONE ?
    			USF_CLOSING_WAIT_NONE : new_serial.closing_wait * 10;
    
    	/*
    	 * This semaphore protects state->count.  It is also
    	 * very useful to prevent opens.  Also, take the
    	 * port configuration semaphore to make sure that a
    	 * module insertion/removal doesn't change anything
    	 * under us.
    	 */
    	mutex_lock(&state->mutex);
    
    	change_irq  = !(port->flags & UPF_FIXED_PORT)
    		&& new_serial.irq != port->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);
    
    	old_flags = port->flags;
    	new_flags = new_serial.flags;
    	old_custom_divisor = port->custom_divisor;
    
    	if (!capable(CAP_SYS_ADMIN)) {
    		retval = -EPERM;
    		if (change_irq || change_port ||
    		    (new_serial.baud_base != port->uartclk / 16) ||
    		    (close_delay != state->close_delay) ||
    		    (closing_wait != state->closing_wait) ||
    		    (new_serial.xmit_fifo_size &&
    		     new_serial.xmit_fifo_size != port->fifosize) ||
    		    (((new_flags ^ old_flags) & ~UPF_USR_MASK) != 0))
    			goto exit;
    		port->flags = ((port->flags & ~UPF_USR_MASK) |
    			       (new_flags & UPF_USR_MASK));
    		port->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 ((new_serial.irq >= NR_IRQS) || (new_serial.irq < 0) ||
    	    (new_serial.baud_base < 9600))
    		retval = -EINVAL;
    
    	if (retval)
    		goto exit;
    
    	if (change_port || change_irq) {
    		retval = -EBUSY;
    
    		/*
    		 * Make sure that we are the sole user of this port.
    		 */
    		if (uart_users(state) > 1)
    			goto exit;
    
    		/*
    		 * We need to shutdown the serial port at the old
    		 * port/type/irq combination.
    		 */
    		uart_shutdown(state);
    	}
    
    	if (change_port) {
    		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;
    
    		/*
    		 * Free and release old regions
    		 */
    		if (old_type != PORT_UNKNOWN)
    			port->ops->release_port(port);
    
    		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;
    
    		/*
    		 * Claim and map the new regions
    		 */
    		if (port->type != PORT_UNKNOWN) {
    			retval = port->ops->request_port(port);
    		} else {
    			/* Always success - Jean II */
    			retval = 0;
    		}
    
    		/*
    		 * If we fail to request resources for the
    		 * 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);
    			/*
    			 * If we failed to restore the old settings,
    			 * we fail like this.
    			 */
    			if (retval)
    				port->type = PORT_UNKNOWN;
    
    			/*
    			 * We failed anyway.
    			 */
    			retval = -EBUSY;
    			/* Added to return the correct error -Ram Gupta */
    			goto exit;
    		}
    	}
    
    	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) |
    				 (new_flags & UPF_CHANGE_MASK);
    	port->custom_divisor   = new_serial.custom_divisor;
    	state->close_delay     = close_delay;
    	state->closing_wait    = closing_wait;
    	if (new_serial.xmit_fifo_size)
    		port->fifosize = new_serial.xmit_fifo_size;
    	if (state->info->tty)
    		state->info->tty->low_latency =
    			(port->flags & UPF_LOW_LATENCY) ? 1 : 0;
    
     check_and_exit:
    	retval = 0;
    	if (port->type == PORT_UNKNOWN)
    		goto exit;
    	if (state->info->flags & UIF_INITIALIZED) {
    		if (((old_flags ^ port->flags) & UPF_SPD_MASK) ||
    		    old_custom_divisor != port->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) {
    				char buf[64];
    				printk(KERN_NOTICE
    				       "%s sets custom speed on %s. This "
    				       "is deprecated.\n", current->comm,
    				       tty_name(state->info->tty, buf));
    			}
    			uart_change_speed(state, NULL);
    		}
    	} else
    		retval = uart_startup(state, 1);
     exit:
    	mutex_unlock(&state->mutex);
    	return retval;
    }
    
    
    /*
     * uart_get_lsr_info - get line status register info.
     * Note: uart_ioctl protects us against hangups.
     */
    static int uart_get_lsr_info(struct uart_state *state,
    			     unsigned int __user *value)
    {
    	struct uart_port *port = state->port;
    	unsigned int result;
    
    	result = port->ops->tx_empty(port);
    
    	/*
    	 * If we're about to load something into the transmit
    	 * register, we'll pretend the transmitter isn't empty to
    	 * avoid a race condition (depending on when the transmit
    	 * interrupt happens).
    	 */
    	if (port->x_char ||
    	    ((uart_circ_chars_pending(&state->info->xmit) > 0) &&
    	     !state->info->tty->stopped && !state->info->tty->hw_stopped))
    		result &= ~TIOCSER_TEMT;
    
    	return put_user(result, value);
    }
    
    static int uart_tiocmget(struct tty_struct *tty, struct file *file)
    {
    	struct uart_state *state = tty->driver_data;
    	struct uart_port *port = state->port;
    	int result = -EIO;
    
    	mutex_lock(&state->mutex);
    	if ((!file || !tty_hung_up_p(file)) &&
    	    !(tty->flags & (1 << TTY_IO_ERROR))) {
    		result = port->mctrl;
    
    		spin_lock_irq(&port->lock);
    		result |= port->ops->get_mctrl(port);
    		spin_unlock_irq(&port->lock);
    	}
    	mutex_unlock(&state->mutex);
    
    	return result;
    }
    
    static int
    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->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);
    		ret = 0;
    	}
    	mutex_unlock(&state->mutex);
    	return ret;
    }
    
    static void uart_break_ctl(struct tty_struct *tty, int break_state)
    {
    	struct uart_state *state = tty->driver_data;
    	struct uart_port *port = state->port;
    
    	BUG_ON(!kernel_locked());
    
    	mutex_lock(&state->mutex);
    
    	if (port->type != PORT_UNKNOWN)
    		port->ops->break_ctl(port, break_state);
    
    	mutex_unlock(&state->mutex);
    }
    
    static int uart_do_autoconfig(struct uart_state *state)
    {
    	struct uart_port *port = state->port;
    	int flags, ret;
    
    	if (!capable(CAP_SYS_ADMIN))
    		return -EPERM;
    
    	/*
    	 * Take the per-port semaphore.  This prevents count from
    	 * changing, and hence any extra opens of the port while
    	 * we're auto-configuring.
    	 */
    	if (mutex_lock_interruptible(&state->mutex))
    		return -ERESTARTSYS;
    
    	ret = -EBUSY;
    	if (uart_users(state) == 1) {
    		uart_shutdown(state);
    
    		/*
    		 * If we already have a port type configured,
    		 * we must release its resources.
    		 */
    		if (port->type != PORT_UNKNOWN)
    			port->ops->release_port(port);
    
    		flags = UART_CONFIG_TYPE;
    		if (port->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);
    
    		ret = uart_startup(state, 1);
    	}
    	mutex_unlock(&state->mutex);
    	return ret;
    }
    
    /*
     * Wait for any of the 4 modem inputs (DCD,RI,DSR,CTS) to change
     * - mask passed in arg for lines of interest
     *   (use |'ed TIOCM_RNG/DSR/CD/CTS for masking)
     * Caller should use TIOCGICOUNT to see which one it was
     */
    static int
    uart_wait_modem_status(struct uart_state *state, unsigned long arg)
    {
    	struct uart_port *port = state->port;
    	DECLARE_WAITQUEUE(wait, current);
    	struct uart_icount cprev, cnow;
    	int ret;
    
    	/*
    	 * note the counters on entry
    	 */
    	spin_lock_irq(&port->lock);
    	memcpy(&cprev, &port->icount, sizeof(struct uart_icount));
    
    	/*
    	 * Force modem status interrupts on
    	 */
    	port->ops->enable_ms(port);
    	spin_unlock_irq(&port->lock);
    
    	add_wait_queue(&state->info->delta_msr_wait, &wait);
    	for (;;) {
    		spin_lock_irq(&port->lock);
    		memcpy(&cnow, &port->icount, sizeof(struct uart_icount));
    		spin_unlock_irq(&port->lock);
    
    		set_current_state(TASK_INTERRUPTIBLE);
    
    		if (((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
    		    ((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
    		    ((arg & TIOCM_CD)  && (cnow.dcd != cprev.dcd)) ||
    		    ((arg & TIOCM_CTS) && (cnow.cts != cprev.cts))) {
    			ret = 0;
    			break;
    		}
    
    		schedule();
    
    		/* see if a signal did it */
    		if (signal_pending(current)) {
    			ret = -ERESTARTSYS;
    			break;
    		}
    
    		cprev = cnow;
    	}
    
    	current->state = TASK_RUNNING;
    	remove_wait_queue(&state->info->delta_msr_wait, &wait);
    
    	return ret;
    }
    
    /*
     * Get counter of input serial line interrupts (DCD,RI,DSR,CTS)
     * Return: write counters to the user passed counter struct
     * NB: both 1->0 and 0->1 transitions are counted except for
     *     RI where only 0->1 is counted.
     */
    static int uart_get_count(struct uart_state *state,
    			  struct serial_icounter_struct __user *icnt)
    {
    	struct serial_icounter_struct icount;
    	struct uart_icount cnow;
    	struct uart_port *port = state->port;
    
    	spin_lock_irq(&port->lock);
    	memcpy(&cnow, &port->icount, sizeof(struct uart_icount));
    	spin_unlock_irq(&port->lock);
    
    	icount.cts         = cnow.cts;
    	icount.dsr         = cnow.dsr;
    	icount.rng         = cnow.rng;
    	icount.dcd         = cnow.dcd;
    	icount.rx          = cnow.rx;
    	icount.tx          = cnow.tx;
    	icount.frame       = cnow.frame;
    	icount.overrun     = cnow.overrun;
    	icount.parity      = cnow.parity;
    	icount.brk         = cnow.brk;
    	icount.buf_overrun = cnow.buf_overrun;
    
    	return copy_to_user(icnt, &icount, sizeof(icount)) ? -EFAULT : 0;
    }
    
    /*
     * Called via sys_ioctl under the BKL.  We can use spin_lock_irq() here.
     */
    static int
    uart_ioctl(struct tty_struct *tty, struct file *filp, unsigned int cmd,
    	   unsigned long arg)
    {
    	struct uart_state *state = tty->driver_data;
    	void __user *uarg = (void __user *)arg;
    	int ret = -ENOIOCTLCMD;
    
    	BUG_ON(!kernel_locked());
    
    	/*
    	 * These ioctls don't rely on the hardware to be present.
    	 */
    	switch (cmd) {
    	case TIOCGSERIAL:
    		ret = uart_get_info(state, uarg);
    		break;
    
    	case TIOCSSERIAL:
    		ret = uart_set_info(state, uarg);
    		break;
    
    	case TIOCSERCONFIG:
    		ret = uart_do_autoconfig(state);
    		break;
    
    	case TIOCSERGWILD: /* obsolete */
    	case TIOCSERSWILD: /* obsolete */
    		ret = 0;
    		break;
    	}
    
    	if (ret != -ENOIOCTLCMD)
    		goto out;
    
    	if (tty->flags & (1 << TTY_IO_ERROR)) {
    		ret = -EIO;
    		goto out;
    	}
    
    	/*
    	 * The following should only be used when hardware is present.
    	 */
    	switch (cmd) {
    	case TIOCMIWAIT:
    		ret = uart_wait_modem_status(state, arg);
    		break;
    
    	case TIOCGICOUNT:
    		ret = uart_get_count(state, uarg);
    		break;
    	}
    
    	if (ret != -ENOIOCTLCMD)
    		goto out;
    
    	mutex_lock(&state->mutex);
    
    	if (tty_hung_up_p(filp)) {
    		ret = -EIO;
    		goto out_up;
    	}
    
    	/*
    	 * All these rely on hardware being present and need to be
    	 * protected against the tty being hung up.
    	 */
    	switch (cmd) {
    	case TIOCSERGETLSR: /* Get line status register */
    		ret = uart_get_lsr_info(state, uarg);
    		break;
    
    	default: {
    		struct uart_port *port = state->port;
    		if (port->ops->ioctl)
    			ret = port->ops->ioctl(port, cmd, arg);
    		break;
    	}
    	}
     out_up:
    	mutex_unlock(&state->mutex);
     out:
    	return ret;
    }
    
    static void uart_set_termios(struct tty_struct *tty,
    						struct ktermios *old_termios)
    {
    	struct uart_state *state = tty->driver_data;
    	unsigned long flags;
    	unsigned int cflag = tty->termios->c_cflag;
    
    	BUG_ON(!kernel_locked());
    
    	/*
    	 * These are the bits that are used to setup various
    	 * flags in the low level driver. We can ignore the Bfoo
    	 * bits in c_cflag; c_[io]speed will always be set
    	 * appropriately by set_termios() in tty_ioctl.c
    	 */
    #define RELEVANT_IFLAG(iflag)	((iflag) & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))
    	if ((cflag ^ old_termios->c_cflag) == 0 &&
    	    tty->termios->c_ospeed == old_termios->c_ospeed &&
    	    tty->termios->c_ispeed == old_termios->c_ispeed &&
    	    RELEVANT_IFLAG(tty->termios->c_iflag ^ old_termios->c_iflag) == 0)
    		return;
    
    	uart_change_speed(state, old_termios);
    
    	/* Handle transition to B0 status */
    	if ((old_termios->c_cflag & CBAUD) && !(cflag & CBAUD))
    		uart_clear_mctrl(state->port, TIOCM_RTS | TIOCM_DTR);
    
    	/* Handle transition away from B0 status */
    	if (!(old_termios->c_cflag & CBAUD) && (cflag & CBAUD)) {
    		unsigned int mask = TIOCM_DTR;
    		if (!(cflag & CRTSCTS) ||
    		    !test_bit(TTY_THROTTLED, &tty->flags))
    			mask |= TIOCM_RTS;
    		uart_set_mctrl(state->port, mask);
    	}
    
    	/* Handle turning off CRTSCTS */
    	if ((old_termios->c_cflag & CRTSCTS) && !(cflag & CRTSCTS)) {
    		spin_lock_irqsave(&state->port->lock, flags);
    		tty->hw_stopped = 0;
    		__uart_start(tty);
    		spin_unlock_irqrestore(&state->port->lock, flags);
    	}
    
    	/* Handle turning on CRTSCTS */
    	if (!(old_termios->c_cflag & CRTSCTS) && (cflag & CRTSCTS)) {
    		spin_lock_irqsave(&state->port->lock, flags);
    		if (!(state->port->ops->get_mctrl(state->port) & TIOCM_CTS)) {
    			tty->hw_stopped = 1;
    			state->port->ops->stop_tx(state->port);
    		}
    		spin_unlock_irqrestore(&state->port->lock, flags);
    	}
    
    #if 0
    	/*
    	 * No need to wake up processes in open wait, since they
    	 * sample the CLOCAL flag once, and don't recheck it.
    	 * XXX  It's not clear whether the current behavior is correct
    	 * or not.  Hence, this may change.....
    	 */
    	if (!(old_termios->c_cflag & CLOCAL) &&
    	    (tty->termios->c_cflag & CLOCAL))
    		wake_up_interruptible(&state->info->open_wait);
    #endif
    }
    
    /*
     * In 2.4.5, calls to this will be serialized via the BKL in
     *  linux/drivers/char/tty_io.c:tty_release()
     *  linux/drivers/char/tty_io.c:do_tty_handup()
     */
    static void uart_close(struct tty_struct *tty, struct file *filp)
    {
    	struct uart_state *state = tty->driver_data;
    	struct uart_port *port;
    
    	BUG_ON(!kernel_locked());
    
    	if (!state || !state->port)
    		return;
    
    	port = state->port;
    
    	pr_debug("uart_close(%d) called\n", port->line);
    
    	mutex_lock(&state->mutex);
    
    	if (tty_hung_up_p(filp))
    		goto done;
    
    	if ((tty->count == 1) && (state->count != 1)) {
    		/*
    		 * Uh, oh.  tty->count is 1, which means that the tty
    		 * structure will be freed.  state->count should always
    		 * be one in these conditions.  If it's greater than
    		 * one, we've got real problems, since it means the
    		 * serial port won't be shutdown.
    		 */
    		printk(KERN_ERR "uart_close: bad serial port count; tty->count is 1, "
    		       "state->count is %d\n", state->count);
    		state->count = 1;
    	}
    	if (--state->count < 0) {
    		printk(KERN_ERR "uart_close: bad serial port count for %s: %d\n",
    		       tty->name, state->count);
    		state->count = 0;
    	}
    	if (state->count)
    		goto done;
    
    	/*
    	 * Now we wait for the transmit buffer to clear; and we notify
    	 * the line discipline to only process XON/XOFF characters by
    	 * setting tty->closing.
    	 */
    	tty->closing = 1;
    
    	if (state->closing_wait != USF_CLOSING_WAIT_NONE)
    		tty_wait_until_sent(tty, msecs_to_jiffies(state->closing_wait));
    
    	/*
    	 * At this point, we stop accepting input.  To do this, we
    	 * disable the receive line status interrupts.
    	 */
    	if (state->info->flags & UIF_INITIALIZED) {
    		unsigned long flags;
    		spin_lock_irqsave(&port->lock, flags);
    		port->ops->stop_rx(port);
    		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_shutdown(state);
    	uart_flush_buffer(tty);
    
    	tty_ldisc_flush(tty);
    
    	tty->closing = 0;
    	state->info->tty = NULL;
    
    	if (state->info->blocked_open) {
    		if (state->close_delay)
    			msleep_interruptible(state->close_delay);
    	} else if (!uart_console(port)) {
    		uart_change_pm(state, 3);
    	}
    
    	/*
    	 * Wake up anyone trying to open this port.
    	 */
    	state->info->flags &= ~UIF_NORMAL_ACTIVE;
    	wake_up_interruptible(&state->info->open_wait);
    
     done:
    	mutex_unlock(&state->mutex);
    }
    
    static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
    {
    	struct uart_state *state = tty->driver_data;
    	struct uart_port *port = state->port;
    	unsigned long char_time, expire;
    
    	BUG_ON(!kernel_locked());
    
    	if (port->type == PORT_UNKNOWN || port->fifosize == 0)
    		return;
    
    	/*
    	 * Set the check interval to be 1/5 of the estimated time to
    	 * send a single character, and make it at least 1.  The check
    	 * interval should also be less than the timeout.
    	 *
    	 * Note: we have to use pretty tight timings here to satisfy
    	 * the NIST-PCTS.
    	 */
    	char_time = (port->timeout - HZ/50) / port->fifosize;
    	char_time = char_time / 5;
    	if (char_time == 0)
    		char_time = 1;
    	if (timeout && timeout < char_time)
    		char_time = timeout;
    
    	/*
    	 * If the transmitter hasn't cleared in twice the approximate
    	 * amount of time to send the entire FIFO, it probably won't
    	 * ever clear.  This assumes the UART isn't doing flow
    	 * control, which is currently the case.  Hence, if it ever
    	 * takes longer than port->timeout, this is probably due to a
    	 * UART bug of some kind.  So, we clamp the timeout parameter at
    	 * 2*port->timeout.
    	 */
    	if (timeout == 0 || timeout > 2 * port->timeout)
    		timeout = 2 * port->timeout;
    
    	expire = jiffies + timeout;
    
    	pr_debug("uart_wait_until_sent(%d), jiffies=%lu, expire=%lu...\n",
    		port->line, jiffies, expire);
    
    	/*
    	 * Check whether the transmitter is empty every 'char_time'.
    	 * 'timeout' / 'expire' give us the maximum amount of time
    	 * we wait.
    	 */
    	while (!port->ops->tx_empty(port)) {
    		msleep_interruptible(jiffies_to_msecs(char_time));
    		if (signal_pending(current))
    			break;
    		if (time_after(jiffies, expire))
    			break;
    	}
    	set_current_state(TASK_RUNNING); /* might not be needed */
    }
    
    /*
     * This is called with the BKL held in
     *  linux/drivers/char/tty_io.c:do_tty_hangup()
     * We're called from the eventd thread, so we can sleep for
     * a _short_ time only.
     */
    static void uart_hangup(struct tty_struct *tty)
    {
    	struct uart_state *state = tty->driver_data;
    
    	BUG_ON(!kernel_locked());
    	pr_debug("uart_hangup(%d)\n", state->port->line);
    
    	mutex_lock(&state->mutex);
    	if (state->info && state->info->flags & UIF_NORMAL_ACTIVE) {
    		uart_flush_buffer(tty);
    		uart_shutdown(state);
    		state->count = 0;
    		state->info->flags &= ~UIF_NORMAL_ACTIVE;
    		state->info->tty = NULL;
    		wake_up_interruptible(&state->info->open_wait);
    		wake_up_interruptible(&state->info->delta_msr_wait);
    	}
    	mutex_unlock(&state->mutex);
    }
    
    /*
     * Copy across the serial console cflag setting into the termios settings
     * for the initial open of the port.  This allows continuity between the
     * kernel settings, and the settings init adopts when it opens the port
     * for the first time.
     */
    static void uart_update_termios(struct uart_state *state)
    {
    	struct tty_struct *tty = state->info->tty;
    	struct uart_port *port = state->port;
    
    	if (uart_console(port) && port->cons->cflag) {
    		tty->termios->c_cflag = port->cons->cflag;
    		port->cons->cflag = 0;
    	}
    
    	/*
    	 * If the device failed to grab its irq resources,
    	 * or some other error occurred, don't try to talk
    	 * to the port hardware.
    	 */
    	if (!(tty->flags & (1 << TTY_IO_ERROR))) {
    		/*
    		 * Make termios settings take effect.
    		 */
    		uart_change_speed(state, NULL);
    
    		/*
    		 * And finally enable the RTS and DTR signals.
    		 */
    		if (tty->termios->c_cflag & CBAUD)
    			uart_set_mctrl(port, TIOCM_DTR | TIOCM_RTS);
    	}
    }
    
    /*
     * Block the open until the port is ready.  We must be called with
     * the per-port semaphore held.
     */
    static int
    uart_block_til_ready(struct file *filp, struct uart_state *state)
    {
    	DECLARE_WAITQUEUE(wait, current);
    	struct uart_info *info = state->info;
    	struct uart_port *port = state->port;
    	unsigned int mctrl;
    
    	info->blocked_open++;
    	state->count--;
    
    	add_wait_queue(&info->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) || info->tty == NULL)
    			break;
    
    		/*
    		 * If the port has been closed, tell userspace/restart open.
    		 */
    		if (!(info->flags & UIF_INITIALIZED))
    			break;
    
    		/*
    		 * If non-blocking mode is set, or CLOCAL mode is set,
    		 * we don't want to wait for the modem status lines to
    		 * indicate that the port is ready.
    		 *
    		 * Also, if the port is not enabled/configured, we want
    		 * to allow the open to succeed here.  Note that we will
    		 * have set TTY_IO_ERROR for a non-existant port.
    		 */
    		if ((filp->f_flags & O_NONBLOCK) ||
    		    (info->tty->termios->c_cflag & CLOCAL) ||
    		    (info->tty->flags & (1 << TTY_IO_ERROR)))
    			break;
    
    		/*
    		 * Set DTR to allow modem to know we're waiting.  Do
    		 * not set RTS here - we want to make sure we catch
    		 * the data from the modem.
    		 */
    		if (info->tty->termios->c_cflag & CBAUD)
    			uart_set_mctrl(port, 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);
    		if (mctrl & TIOCM_CAR)
    			break;
    
    		mutex_unlock(&state->mutex);
    		schedule();
    		mutex_lock(&state->mutex);
    
    		if (signal_pending(current))
    			break;
    	}
    	set_current_state(TASK_RUNNING);
    	remove_wait_queue(&info->open_wait, &wait);
    
    	state->count++;
    	info->blocked_open--;
    
    	if (signal_pending(current))
    		return -ERESTARTSYS;
    
    	if (!info->tty || tty_hung_up_p(filp))
    		return -EAGAIN;
    
    	return 0;
    }
    
    static struct uart_state *uart_get(struct uart_driver *drv, int line)
    {
    	struct uart_state *state;
    	int ret = 0;
    
    	state = drv->state + line;
    	if (mutex_lock_interruptible(&state->mutex)) {
    		ret = -ERESTARTSYS;
    		goto err;
    	}
    
    	state->count++;
    	if (!state->port || state->port->flags & UPF_DEAD) {
    		ret = -ENXIO;
    		goto err_unlock;
    	}
    
    	if (!state->info) {
    		state->info = kzalloc(sizeof(struct uart_info), GFP_KERNEL);
    		if (state->info) {
    			init_waitqueue_head(&state->info->open_wait);
    			init_waitqueue_head(&state->info->delta_msr_wait);
    
    			/*
    			 * Link the info into the other structures.
    			 */
    			state->port->info = state->info;
    
    			tasklet_init(&state->info->tlet, uart_tasklet_action,
    				     (unsigned long)state);
    		} else {
    			ret = -ENOMEM;
    			goto err_unlock;
    		}
    	}
    	return state;
    
     err_unlock:
    	state->count--;
    	mutex_unlock(&state->mutex);
     err:
    	return ERR_PTR(ret);
    }
    
    /*
     * calls to uart_open are serialised by the BKL in
     *   fs/char_dev.c:chrdev_open()
     * Note that if this fails, then uart_close() _will_ be called.
     *
     * In time, we want to scrap the "opening nonpresent ports"
     * behaviour and implement an alternative way for setserial
     * to set base addresses/ports/types.  This will allow us to
     * get rid of a certain amount of extra tests.
     */
    static int uart_open(struct tty_struct *tty, struct file *filp)
    {
    	struct uart_driver *drv = (struct uart_driver *)tty->driver->driver_state;
    	struct uart_state *state;
    	int retval, line = tty->index;
    
    	BUG_ON(!kernel_locked());
    	pr_debug("uart_open(%d) called\n", line);
    
    	/*
    	 * tty->driver->num won't change, so we won't fail here with
    	 * tty->driver_data set to something non-NULL (and therefore
    	 * we won't get caught by uart_close()).
    	 */
    	retval = -ENODEV;
    	if (line >= tty->driver->num)
    		goto fail;
    
    	/*
    	 * We take the semaphore inside uart_get to guarantee that we won't
    	 * be re-entered while allocating the info structure, or while we
    	 * request any IRQs that the driver may need.  This also has the nice
    	 * side-effect that it delays the action of uart_hangup, so we can
    	 * guarantee that info->tty will always contain something reasonable.
    	 */
    	state = uart_get(drv, line);
    	if (IS_ERR(state)) {
    		retval = PTR_ERR(state);
    		goto fail;
    	}
    
    	/*
    	 * Once we set tty->driver_data here, we are guaranteed that
    	 * uart_close() will decrement the driver module use count.
    	 * Any failures from here onwards should not touch the count.
    	 */
    	tty->driver_data = state;
    	tty->low_latency = (state->port->flags & UPF_LOW_LATENCY) ? 1 : 0;
    	tty->alt_speed = 0;
    	state->info->tty = tty;
    
    	/*
    	 * If the port is in the middle of closing, bail out now.
    	 */
    	if (tty_hung_up_p(filp)) {
    		retval = -EAGAIN;
    		state->count--;
    		mutex_unlock(&state->mutex);
    		goto fail;
    	}
    
    	/*
    	 * Make sure the device is in D0 state.
    	 */
    	if (state->count == 1)
    		uart_change_pm(state, 0);
    
    	/*
    	 * Start up the serial port.
    	 */
    	retval = uart_startup(state, 0);
    
    	/*
    	 * If we succeeded, wait until the port is ready.
    	 */
    	if (retval == 0)
    		retval = uart_block_til_ready(filp, state);
    	mutex_unlock(&state->mutex);
    
    	/*
    	 * If this is the first open to succeed, adjust things to suit.
    	 */
    	if (retval == 0 && !(state->info->flags & UIF_NORMAL_ACTIVE)) {
    		state->info->flags |= UIF_NORMAL_ACTIVE;
    
    		uart_update_termios(state);
    	}
    
     fail:
    	return retval;
    }
    
    static const char *uart_type(struct uart_port *port)
    {
    	const char *str = NULL;
    
    	if (port->ops->type)
    		str = port->ops->type(port);
    
    	if (!str)
    		str = "unknown";
    
    	return str;
    }
    
    #ifdef CONFIG_PROC_FS
    
    static int uart_line_info(char *buf, struct uart_driver *drv, int i)
    {
    	struct uart_state *state = drv->state + i;
    	int pm_state;
    	struct uart_port *port = state->port;
    	char stat_buf[32];
    	unsigned int status;
    	int mmio, ret;
    
    	if (!port)
    		return 0;
    
    	mmio = port->iotype >= UPIO_MEM;
    	ret = sprintf(buf, "%d: uart:%s %s%08llX irq:%d",
    			port->line, uart_type(port),
    			mmio ? "mmio:0x" : "port:",
    			mmio ? (unsigned long long)port->mapbase
    			     : (unsigned long long) port->iobase,
    			port->irq);
    
    	if (port->type == PORT_UNKNOWN) {
    		strcat(buf, "\n");
    		return ret + 1;
    	}
    
    	if (capable(CAP_SYS_ADMIN)) {
    		mutex_lock(&state->mutex);
    		pm_state = state->pm_state;
    		if (pm_state)
    			uart_change_pm(state, 0);
    		spin_lock_irq(&port->lock);
    		status = port->ops->get_mctrl(port);
    		spin_unlock_irq(&port->lock);
    		if (pm_state)
    			uart_change_pm(state, pm_state);
    		mutex_unlock(&state->mutex);
    
    		ret += sprintf(buf + ret, " tx:%d rx:%d",
    				port->icount.tx, port->icount.rx);
    		if (port->icount.frame)
    			ret += sprintf(buf + ret, " fe:%d",
    				port->icount.frame);
    		if (port->icount.parity)
    			ret += sprintf(buf + ret, " pe:%d",
    				port->icount.parity);
    		if (port->icount.brk)
    			ret += sprintf(buf + ret, " brk:%d",
    				port->icount.brk);
    		if (port->icount.overrun)
    			ret += sprintf(buf + ret, " oe:%d",
    				port->icount.overrun);
    
    #define INFOBIT(bit, str) \
    	if (port->mctrl & (bit)) \
    		strncat(stat_buf, (str), sizeof(stat_buf) - \
    			strlen(stat_buf) - 2)
    #define STATBIT(bit, str) \
    	if (status & (bit)) \
    		strncat(stat_buf, (str), sizeof(stat_buf) - \
    		       strlen(stat_buf) - 2)
    
    		stat_buf[0] = '\0';
    		stat_buf[1] = '\0';
    		INFOBIT(TIOCM_RTS, "|RTS");
    		STATBIT(TIOCM_CTS, "|CTS");
    		INFOBIT(TIOCM_DTR, "|DTR");
    		STATBIT(TIOCM_DSR, "|DSR");
    		STATBIT(TIOCM_CAR, "|CD");
    		STATBIT(TIOCM_RNG, "|RI");
    		if (stat_buf[0])
    			stat_buf[0] = ' ';
    		strcat(stat_buf, "\n");
    
    		ret += sprintf(buf + ret, stat_buf);
    	} else {
    		strcat(buf, "\n");
    		ret++;
    	}
    #undef STATBIT
    #undef INFOBIT
    	return ret;
    }
    
    static int uart_read_proc(char *page, char **start, off_t off,
    			  int count, int *eof, void *data)
    {
    	struct tty_driver *ttydrv = data;
    	struct uart_driver *drv = ttydrv->driver_state;
    	int i, len = 0, l;
    	off_t begin = 0;
    
    	len += sprintf(page, "serinfo:1.0 driver%s%s revision:%s\n",
    			"", "", "");
    	for (i = 0; i < drv->nr && len < PAGE_SIZE - 96; i++) {
    		l = uart_line_info(page + len, drv, i);
    		len += l;
    		if (len + begin > off + count)
    			goto done;
    		if (len + begin < off) {
    			begin += len;
    			len = 0;
    		}
    	}
    	*eof = 1;
     done:
    	if (off >= len + begin)
    		return 0;
    	*start = page + (off - begin);
    	return (count < begin + len - off) ? count : (begin + len - off);
    }
    #endif
    
    #if defined(CONFIG_SERIAL_CORE_CONSOLE) || defined(CONFIG_CONSOLE_POLL)
    /*
     *	uart_console_write - write a console message to a serial port
     *	@port: the port to write the message
     *	@s: array of characters
     *	@count: number of characters in string to write
     *	@write: function to write character to port
     */
    void uart_console_write(struct uart_port *port, const char *s,
    			unsigned int count,
    			void (*putchar)(struct uart_port *, int))
    {
    	unsigned int i;
    
    	for (i = 0; i < count; i++, s++) {
    		if (*s == '\n')
    			putchar(port, '\r');
    		putchar(port, *s);
    	}
    }
    EXPORT_SYMBOL_GPL(uart_console_write);
    
    /*
     *	Check whether an invalid uart number has been specified, and
     *	if so, search for the first available port that does have
     *	console support.
     */
    struct uart_port * __init
    uart_get_console(struct uart_port *ports, int nr, struct console *co)
    {
    	int idx = co->index;
    
    	if (idx < 0 || idx >= nr || (ports[idx].iobase == 0 &&
    				     ports[idx].membase == NULL))
    		for (idx = 0; idx < nr; idx++)
    			if (ports[idx].iobase != 0 ||
    			    ports[idx].membase != NULL)
    				break;
    
    	co->index = idx;
    
    	return ports + idx;
    }
    
    /**
     *	uart_parse_options - Parse serial port baud/parity/bits/flow contro.
     *	@options: pointer to option string
     *	@baud: pointer to an 'int' variable for the baud rate.
     *	@parity: pointer to an 'int' variable for the parity.
     *	@bits: pointer to an 'int' variable for the number of data bits.
     *	@flow: pointer to an 'int' variable for the flow control character.
     *
     *	uart_parse_options decodes a string containing the serial console
     *	options.  The format of the string is <baud><parity><bits><flow>,
     *	eg: 115200n8r
     */
    void
    uart_parse_options(char *options, int *baud, int *parity, int *bits, int *flow)
    {
    	char *s = options;
    
    	*baud = simple_strtoul(s, NULL, 10);
    	while (*s >= '0' && *s <= '9')
    		s++;
    	if (*s)
    		*parity = *s++;
    	if (*s)
    		*bits = *s++ - '0';
    	if (*s)
    		*flow = *s;
    }
    EXPORT_SYMBOL_GPL(uart_parse_options);
    
    struct baud_rates {
    	unsigned int rate;
    	unsigned int cflag;
    };
    
    static const struct baud_rates baud_rates[] = {
    	{ 921600, B921600 },
    	{ 460800, B460800 },
    	{ 230400, B230400 },
    	{ 115200, B115200 },
    	{  57600, B57600  },
    	{  38400, B38400  },
    	{  19200, B19200  },
    	{   9600, B9600   },
    	{   4800, B4800   },
    	{   2400, B2400   },
    	{   1200, B1200   },
    	{      0, B38400  }
    };
    
    /**
     *	uart_set_options - setup the serial console parameters
     *	@port: pointer to the serial ports uart_port structure
     *	@co: console pointer
     *	@baud: baud rate
     *	@parity: parity character - 'n' (none), 'o' (odd), 'e' (even)
     *	@bits: number of data bits
     *	@flow: flow control character - 'r' (rts)
     */
    int
    uart_set_options(struct uart_port *port, struct console *co,
    		 int baud, int parity, int bits, int flow)
    {
    	struct ktermios termios;
    	static struct ktermios dummy;
    	int i;
    
    	/*
    	 * Ensure that the serial console lock is initialised
    	 * early.
    	 */
    	spin_lock_init(&port->lock);
    	lockdep_set_class(&port->lock, &port_lock_key);
    
    	memset(&termios, 0, sizeof(struct ktermios));
    
    	termios.c_cflag = CREAD | HUPCL | CLOCAL;
    
    	/*
    	 * Construct a cflag setting.
    	 */
    	for (i = 0; baud_rates[i].rate; i++)
    		if (baud_rates[i].rate <= baud)
    			break;
    
    	termios.c_cflag |= baud_rates[i].cflag;
    
    	if (bits == 7)
    		termios.c_cflag |= CS7;
    	else
    		termios.c_cflag |= CS8;
    
    	switch (parity) {
    	case 'o': case 'O':
    		termios.c_cflag |= PARODD;
    		/*fall through*/
    	case 'e': case 'E':
    		termios.c_cflag |= PARENB;
    		break;
    	}
    
    	if (flow == 'r')
    		termios.c_cflag |= CRTSCTS;
    
    	/*
    	 * some uarts on other side don't support no flow control.
    	 * So we set * DTR in host uart to make them happy
    	 */
    	port->mctrl |= TIOCM_DTR;
    
    	port->ops->set_termios(port, &termios, &dummy);
    	/*
    	 * Allow the setting of the UART parameters with a NULL console
    	 * too:
    	 */
    	if (co)
    		co->cflag = termios.c_cflag;
    
    	return 0;
    }
    EXPORT_SYMBOL_GPL(uart_set_options);
    #endif /* CONFIG_SERIAL_CORE_CONSOLE */
    
    static void uart_change_pm(struct uart_state *state, int pm_state)
    {
    	struct uart_port *port = state->port;
    
    	if (state->pm_state != pm_state) {
    		if (port->ops->pm)
    			port->ops->pm(port, pm_state, state->pm_state);
    		state->pm_state = pm_state;
    	}
    }
    
    struct uart_match {
    	struct uart_port *port;
    	struct uart_driver *driver;
    };
    
    static int serial_match_port(struct device *dev, void *data)
    {
    	struct uart_match *match = data;
    	dev_t devt = MKDEV(match->driver->major, match->driver->minor) + match->port->line;
    
    	return dev->devt == devt; /* Actually, only one tty per port */
    }
    
    int uart_suspend_port(struct uart_driver *drv, struct uart_port *port)
    {
    	struct uart_state *state = drv->state + port->line;
    	struct device *tty_dev;
    	struct uart_match match = {port, drv};
    
    	mutex_lock(&state->mutex);
    
    	if (!console_suspend_enabled && uart_console(port)) {
    		/* we're going to avoid suspending serial console */
    		mutex_unlock(&state->mutex);
    		return 0;
    	}
    
    	tty_dev = device_find_child(port->dev, &match, serial_match_port);
    	if (device_may_wakeup(tty_dev)) {
    		enable_irq_wake(port->irq);
    		put_device(tty_dev);
    		mutex_unlock(&state->mutex);
    		return 0;
    	}
    	port->suspended = 1;
    
    	if (state->info && state->info->flags & UIF_INITIALIZED) {
    		const struct uart_ops *ops = port->ops;
    		int tries;
    
    		state->info->flags = (state->info->flags & ~UIF_INITIALIZED)
    				     | UIF_SUSPENDED;
    
    		spin_lock_irq(&port->lock);
    		ops->stop_tx(port);
    		ops->set_mctrl(port, 0);
    		ops->stop_rx(port);
    		spin_unlock_irq(&port->lock);
    
    		/*
    		 * Wait for the transmitter to empty.
    		 */
    		for (tries = 3; !ops->tx_empty(port) && tries; tries--)
    			msleep(10);
    		if (!tries)
    			printk(KERN_ERR "%s%s%s%d: Unable to drain "
    					"transmitter\n",
    			       port->dev ? port->dev->bus_id : "",
    			       port->dev ? ": " : "",
    			       drv->dev_name, port->line);
    
    		ops->shutdown(port);
    	}
    
    	/*
    	 * Disable the console device before suspending.
    	 */
    	if (uart_console(port))
    		console_stop(port->cons);
    
    	uart_change_pm(state, 3);
    
    	mutex_unlock(&state->mutex);
    
    	return 0;
    }
    
    int uart_resume_port(struct uart_driver *drv, struct uart_port *port)
    {
    	struct uart_state *state = drv->state + port->line;
    
    	mutex_lock(&state->mutex);
    
    	if (!console_suspend_enabled && uart_console(port)) {
    		/* no need to resume serial console, it wasn't suspended */
    		mutex_unlock(&state->mutex);
    		return 0;
    	}
    
    	if (!port->suspended) {
    		disable_irq_wake(port->irq);
    		mutex_unlock(&state->mutex);
    		return 0;
    	}
    	port->suspended = 0;
    
    	/*
    	 * Re-enable the console device after suspending.
    	 */
    	if (uart_console(port)) {
    		struct ktermios termios;
    
    		/*
    		 * First try to use the console cflag setting.
    		 */
    		memset(&termios, 0, sizeof(struct ktermios));
    		termios.c_cflag = port->cons->cflag;
    
    		/*
    		 * If that's unset, use the tty termios setting.
    		 */
    		if (state->info && state->info->tty && termios.c_cflag == 0)
    			termios = *state->info->tty->termios;
    
    		uart_change_pm(state, 0);
    		port->ops->set_termios(port, &termios, NULL);
    		console_start(port->cons);
    	}
    
    	if (state->info && state->info->flags & UIF_SUSPENDED) {
    		const struct uart_ops *ops = port->ops;
    		int ret;
    
    		uart_change_pm(state, 0);
    		ops->set_mctrl(port, 0);
    		ret = ops->startup(port);
    		if (ret == 0) {
    			uart_change_speed(state, NULL);
    			spin_lock_irq(&port->lock);
    			ops->set_mctrl(port, port->mctrl);
    			ops->start_tx(port);
    			spin_unlock_irq(&port->lock);
    			state->info->flags |= UIF_INITIALIZED;
    		} else {
    			/*
    			 * Failed to resume - maybe hardware went away?
    			 * Clear the "initialized" flag so we won't try
    			 * to call the low level drivers shutdown method.
    			 */
    			uart_shutdown(state);
    		}
    
    		state->info->flags &= ~UIF_SUSPENDED;
    	}
    
    	mutex_unlock(&state->mutex);
    
    	return 0;
    }
    
    static inline void
    uart_report_port(struct uart_driver *drv, struct uart_port *port)
    {
    	char address[64];
    
    	switch (port->iotype) {
    	case UPIO_PORT:
    		snprintf(address, sizeof(address),
    			 "I/O 0x%x", port->iobase);
    		break;
    	case UPIO_HUB6:
    		snprintf(address, sizeof(address),
    			 "I/O 0x%x offset 0x%x", port->iobase, port->hub6);
    		break;
    	case UPIO_MEM:
    	case UPIO_MEM32:
    	case UPIO_AU:
    	case UPIO_TSI:
    	case UPIO_DWAPB:
    		snprintf(address, sizeof(address),
    			 "MMIO 0x%llx", (unsigned long long)port->mapbase);
    		break;
    	default:
    		strlcpy(address, "*unknown*", sizeof(address));
    		break;
    	}
    
    	printk(KERN_INFO "%s%s%s%d at %s (irq = %d) is a %s\n",
    	       port->dev ? port->dev->bus_id : "",
    	       port->dev ? ": " : "",
    	       drv->dev_name, port->line, address, port->irq, uart_type(port));
    }
    
    static void
    uart_configure_port(struct uart_driver *drv, struct uart_state *state,
    		    struct uart_port *port)
    {
    	unsigned int flags;
    
    	/*
    	 * If there isn't a port here, don't do anything further.
    	 */
    	if (!port->iobase && !port->mapbase && !port->membase)
    		return;
    
    	/*
    	 * Now do the auto configuration stuff.  Note that config_port
    	 * is expected to claim the resources and map the port for us.
    	 */
    	flags = UART_CONFIG_TYPE;
    	if (port->flags & UPF_AUTO_IRQ)
    		flags |= UART_CONFIG_IRQ;
    	if (port->flags & UPF_BOOT_AUTOCONF) {
    		port->type = PORT_UNKNOWN;
    		port->ops->config_port(port, flags);
    	}
    
    	if (port->type != PORT_UNKNOWN) {
    		unsigned long flags;
    
    		uart_report_port(drv, port);
    
    		/* Power up port for set_mctrl() */
    		uart_change_pm(state, 0);
    
    		/*
    		 * Ensure that the modem control lines are de-activated.
    		 * keep the DTR setting that is set in uart_set_options()
    		 * We probably don't need a spinlock around this, but
    		 */
    		spin_lock_irqsave(&port->lock, flags);
    		port->ops->set_mctrl(port, port->mctrl & TIOCM_DTR);
    		spin_unlock_irqrestore(&port->lock, flags);
    
    		/*
    		 * If this driver supports console, and it hasn't been
    		 * successfully registered yet, try to re-register it.
    		 * It may be that the port was not available.
    		 */
    		if (port->cons && !(port->cons->flags & CON_ENABLED))
    			register_console(port->cons);
    
    		/*
    		 * Power down all ports by default, except the
    		 * console if we have one.
    		 */
    		if (!uart_console(port))
    			uart_change_pm(state, 3);
    	}
    }
    
    #ifdef CONFIG_CONSOLE_POLL
    
    static int uart_poll_init(struct tty_driver *driver, int line, char *options)
    {
    	struct uart_driver *drv = driver->driver_state;
    	struct uart_state *state = drv->state + line;
    	struct uart_port *port;
    	int baud = 9600;
    	int bits = 8;
    	int parity = 'n';
    	int flow = 'n';
    
    	if (!state || !state->port)
    		return -1;
    
    	port = state->port;
    	if (!(port->ops->poll_get_char && port->ops->poll_put_char))
    		return -1;
    
    	if (options) {
    		uart_parse_options(options, &baud, &parity, &bits, &flow);
    		return uart_set_options(port, NULL, baud, parity, bits, flow);
    	}
    
    	return 0;
    }
    
    static int uart_poll_get_char(struct tty_driver *driver, int line)
    {
    	struct uart_driver *drv = driver->driver_state;
    	struct uart_state *state = drv->state + line;
    	struct uart_port *port;
    
    	if (!state || !state->port)
    		return -1;
    
    	port = state->port;
    	return port->ops->poll_get_char(port);
    }
    
    static void uart_poll_put_char(struct tty_driver *driver, int line, char ch)
    {
    	struct uart_driver *drv = driver->driver_state;
    	struct uart_state *state = drv->state + line;
    	struct uart_port *port;
    
    	if (!state || !state->port)
    		return;
    
    	port = state->port;
    	port->ops->poll_put_char(port, ch);
    }
    #endif
    
    static const struct tty_operations uart_ops = {
    	.open		= uart_open,
    	.close		= uart_close,
    	.write		= uart_write,
    	.put_char	= uart_put_char,
    	.flush_chars	= uart_flush_chars,
    	.write_room	= uart_write_room,
    	.chars_in_buffer= uart_chars_in_buffer,
    	.flush_buffer	= uart_flush_buffer,
    	.ioctl		= uart_ioctl,
    	.throttle	= uart_throttle,
    	.unthrottle	= uart_unthrottle,
    	.send_xchar	= uart_send_xchar,
    	.set_termios	= uart_set_termios,
    	.stop		= uart_stop,
    	.start		= uart_start,
    	.hangup		= uart_hangup,
    	.break_ctl	= uart_break_ctl,
    	.wait_until_sent= uart_wait_until_sent,
    #ifdef CONFIG_PROC_FS
    	.read_proc	= uart_read_proc,
    #endif
    	.tiocmget	= uart_tiocmget,
    	.tiocmset	= uart_tiocmset,
    #ifdef CONFIG_CONSOLE_POLL
    	.poll_init	= uart_poll_init,
    	.poll_get_char	= uart_poll_get_char,
    	.poll_put_char	= uart_poll_put_char,
    #endif
    };
    
    /**
     *	uart_register_driver - register a driver with the uart core layer
     *	@drv: low level driver structure
     *
     *	Register a uart driver with the core driver.  We in turn register
     *	with the tty layer, and initialise the core driver per-port state.
     *
     *	We have a proc file in /proc/tty/driver which is named after the
     *	normal driver.
     *
     *	drv->port should be NULL, and the per-port structures should be
     *	registered using uart_add_one_port after this call has succeeded.
     */
    int uart_register_driver(struct uart_driver *drv)
    {
    	struct tty_driver *normal = NULL;
    	int i, retval;
    
    	BUG_ON(drv->state);
    
    	/*
    	 * Maybe we should be using a slab cache for this, especially if
    	 * we have a large number of ports to handle.
    	 */
    	drv->state = kzalloc(sizeof(struct uart_state) * drv->nr, GFP_KERNEL);
    	retval = -ENOMEM;
    	if (!drv->state)
    		goto out;
    
    	normal  = alloc_tty_driver(drv->nr);
    	if (!normal)
    		goto out;
    
    	drv->tty_driver = normal;
    
    	normal->owner		= drv->owner;
    	normal->driver_name	= drv->driver_name;
    	normal->name		= drv->dev_name;
    	normal->major		= drv->major;
    	normal->minor_start	= drv->minor;
    	normal->type		= TTY_DRIVER_TYPE_SERIAL;
    	normal->subtype		= SERIAL_TYPE_NORMAL;
    	normal->init_termios	= tty_std_termios;
    	normal->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
    	normal->init_termios.c_ispeed = normal->init_termios.c_ospeed = 9600;
    	normal->flags		= TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
    	normal->driver_state    = drv;
    	tty_set_operations(normal, &uart_ops);
    
    	/*
    	 * Initialise the UART state(s).
    	 */
    	for (i = 0; i < drv->nr; i++) {
    		struct uart_state *state = drv->state + i;
    
    		state->close_delay     = 500;	/* .5 seconds */
    		state->closing_wait    = 30000;	/* 30 seconds */
    
    		mutex_init(&state->mutex);
    	}
    
    	retval = tty_register_driver(normal);
     out:
    	if (retval < 0) {
    		put_tty_driver(normal);
    		kfree(drv->state);
    	}
    	return retval;
    }
    
    /**
     *	uart_unregister_driver - remove a driver from the uart core layer
     *	@drv: low level driver structure
     *
     *	Remove all references to a driver from the core driver.  The low
     *	level driver must have removed all its ports via the
     *	uart_remove_one_port() if it registered them with uart_add_one_port().
     *	(ie, drv->port == NULL)
     */
    void uart_unregister_driver(struct uart_driver *drv)
    {
    	struct tty_driver *p = drv->tty_driver;
    	tty_unregister_driver(p);
    	put_tty_driver(p);
    	kfree(drv->state);
    	drv->tty_driver = NULL;
    }
    
    struct tty_driver *uart_console_device(struct console *co, int *index)
    {
    	struct uart_driver *p = co->data;
    	*index = co->index;
    	return p->tty_driver;
    }
    
    /**
     *	uart_add_one_port - attach a driver-defined port structure
     *	@drv: pointer to the uart low level driver structure for this port
     *	@port: uart port structure to use for this port.
     *
     *	This allows the driver to register its own uart_port structure
     *	with the core driver.  The main purpose is to allow the low
     *	level uart drivers to expand uart_port, rather than having yet
     *	more levels of structures.
     */
    int uart_add_one_port(struct uart_driver *drv, struct uart_port *port)
    {
    	struct uart_state *state;
    	int ret = 0;
    	struct device *tty_dev;
    
    	BUG_ON(in_interrupt());
    
    	if (port->line >= drv->nr)
    		return -EINVAL;
    
    	state = drv->state + port->line;
    
    	mutex_lock(&port_mutex);
    	mutex_lock(&state->mutex);
    	if (state->port) {
    		ret = -EINVAL;
    		goto out;
    	}
    
    	state->port = port;
    	state->pm_state = -1;
    
    	port->cons = drv->cons;
    	port->info = state->info;
    
    	/*
    	 * If this port is a console, then the spinlock is already
    	 * initialised.
    	 */
    	if (!(uart_console(port) && (port->cons->flags & CON_ENABLED))) {
    		spin_lock_init(&port->lock);
    		lockdep_set_class(&port->lock, &port_lock_key);
    	}
    
    	uart_configure_port(drv, state, port);
    
    	/*
    	 * Register the port whether it's detected or not.  This allows
    	 * setserial to be used to alter this ports parameters.
    	 */
    	tty_dev = tty_register_device(drv->tty_driver, port->line, port->dev);
    	if (likely(!IS_ERR(tty_dev))) {
    		device_init_wakeup(tty_dev, 1);
    		device_set_wakeup_enable(tty_dev, 0);
    	} else
    		printk(KERN_ERR "Cannot register tty device on line %d\n",
    		       port->line);
    
    	/*
    	 * Ensure UPF_DEAD is not set.
    	 */
    	port->flags &= ~UPF_DEAD;
    
     out:
    	mutex_unlock(&state->mutex);
    	mutex_unlock(&port_mutex);
    
    	return ret;
    }
    
    /**
     *	uart_remove_one_port - detach a driver defined port structure
     *	@drv: pointer to the uart low level driver structure for this port
     *	@port: uart port structure for this port
     *
     *	This unhooks (and hangs up) the specified port structure from the
     *	core driver.  No further calls will be made to the low-level code
     *	for this port.
     */
    int uart_remove_one_port(struct uart_driver *drv, struct uart_port *port)
    {
    	struct uart_state *state = drv->state + port->line;
    	struct uart_info *info;
    
    	BUG_ON(in_interrupt());
    
    	if (state->port != port)
    		printk(KERN_ALERT "Removing wrong port: %p != %p\n",
    			state->port, port);
    
    	mutex_lock(&port_mutex);
    
    	/*
    	 * Mark the port "dead" - this prevents any opens from
    	 * succeeding while we shut down the port.
    	 */
    	mutex_lock(&state->mutex);
    	port->flags |= UPF_DEAD;
    	mutex_unlock(&state->mutex);
    
    	/*
    	 * Remove the devices from the tty layer
    	 */
    	tty_unregister_device(drv->tty_driver, port->line);
    
    	info = state->info;
    	if (info && info->tty)
    		tty_vhangup(info->tty);
    
    	/*
    	 * All users of this port should now be disconnected from
    	 * this driver, and the port shut down.  We should be the
    	 * only thread fiddling with this port from now on.
    	 */
    	state->info = NULL;
    
    	/*
    	 * Free the port IO and memory resources, if any.
    	 */
    	if (port->type != PORT_UNKNOWN)
    		port->ops->release_port(port);
    
    	/*
    	 * Indicate that there isn't a port here anymore.
    	 */
    	port->type = PORT_UNKNOWN;
    
    	/*
    	 * Kill the tasklet, and free resources.
    	 */
    	if (info) {
    		tasklet_kill(&info->tlet);
    		kfree(info);
    	}
    
    	state->port = NULL;
    	mutex_unlock(&port_mutex);
    
    	return 0;
    }
    
    /*
     *	Are the two ports equivalent?
     */
    int uart_match_port(struct uart_port *port1, struct uart_port *port2)
    {
    	if (port1->iotype != port2->iotype)
    		return 0;
    
    	switch (port1->iotype) {
    	case UPIO_PORT:
    		return (port1->iobase == port2->iobase);
    	case UPIO_HUB6:
    		return (port1->iobase == port2->iobase) &&
    		       (port1->hub6   == port2->hub6);
    	case UPIO_MEM:
    	case UPIO_MEM32:
    	case UPIO_AU:
    	case UPIO_TSI:
    	case UPIO_DWAPB:
    		return (port1->mapbase == port2->mapbase);
    	}
    	return 0;
    }
    EXPORT_SYMBOL(uart_match_port);
    
    EXPORT_SYMBOL(uart_write_wakeup);
    EXPORT_SYMBOL(uart_register_driver);
    EXPORT_SYMBOL(uart_unregister_driver);
    EXPORT_SYMBOL(uart_suspend_port);
    EXPORT_SYMBOL(uart_resume_port);
    EXPORT_SYMBOL(uart_add_one_port);
    EXPORT_SYMBOL(uart_remove_one_port);
    
    MODULE_DESCRIPTION("Serial driver core");
    MODULE_LICENSE("GPL");