text: // SPDX-License-Identifier: GPL-2.0+
  /*
   *  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.
   */
  #include <linux/module.h>
  #include <linux/tty.h>
  #include <linux/tty_flip.h>
  #include <linux/slab.h>
  #include <linux/sched/signal.h>
  #include <linux/init.h>
  #include <linux/console.h>
  #include <linux/of.h>
  #include <linux/proc_fs.h>
  #include <linux/seq_file.h>
  #include <linux/device.h>
  #include <linux/serial.h> /* for serial_state and serial_icounter_struct */
  #include <linux/serial_core.h>
  #include <linux/delay.h>
  #include <linux/mutex.h>
  
  #include <linux/irq.h>
  #include <linux/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)
  
  static void uart_change_speed(struct tty_struct *tty, 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,
  			   enum uart_pm_state pm_state);
  
  static void uart_port_shutdown(struct tty_port *port);
  
  static int uart_dcd_enabled(struct uart_port *uport)
  {
  	return !!(uport->status & UPSTAT_DCD_ENABLE);
  }
  
  static inline struct uart_port *uart_port_ref(struct uart_state *state)
  {
  	if (atomic_add_unless(&state->refcount, 1, 0))
  		return state->uart_port;
  	return NULL;
  }
  
  static inline void uart_port_deref(struct uart_port *uport)
  {
  	if (atomic_dec_and_test(&uport->state->refcount))
  		wake_up(&uport->state->remove_wait);
  }
  
  #define uart_port_lock(state, flags)					\
  	({								\
  		struct uart_port *__uport = uart_port_ref(state);	\
  		if (__uport)						\
  			spin_lock_irqsave(&__uport->lock, flags);	\
  		__uport;						\
  	})
  
  #define uart_port_unlock(uport, flags)					\
  	({								\
  		struct uart_port *__uport = uport;			\
  		if (__uport) {						\
  			spin_unlock_irqrestore(&__uport->lock, flags);	\
  			uart_port_deref(__uport);			\
  		}							\
  	})
  
  static inline struct uart_port *uart_port_check(struct uart_state *state)
  {
  	lockdep_assert_held(&state->port.mutex);
  	return state->uart_port;
  }
  
  /*
   * 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_state *state = port->state;
  	/*
  	 * This means you called this function _after_ the port was
  	 * closed.  No cookie for you.
  	 */
  	BUG_ON(!state);
  	tty_port_tty_wakeup(&state->port);
  }
  
  static void uart_stop(struct tty_struct *tty)
  {
  	struct uart_state *state = tty->driver_data;
  	struct uart_port *port;
  	unsigned long flags;
  
  	port = uart_port_lock(state, flags);
  	if (port)
  		port->ops->stop_tx(port);
  	uart_port_unlock(port, flags);
  }
  
  static void __uart_start(struct tty_struct *tty)
  {
  	struct uart_state *state = tty->driver_data;
  	struct uart_port *port = state->uart_port;
  
  	if (port && !uart_tx_stopped(port))
  		port->ops->start_tx(port);
  }
  
  static void uart_start(struct tty_struct *tty)
  {
  	struct uart_state *state = tty->driver_data;
  	struct uart_port *port;
  	unsigned long flags;
  
  	if (!state)
  		return;
  
  	port = uart_port_lock(state, flags);
  	__uart_start(tty);
  	uart_port_unlock(port, flags);
  }
  
  static 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)
  
  static void uart_port_dtr_rts(struct uart_port *uport, int raise)
  {
  	int rs485_on = uport->rs485_config &&
  		(uport->rs485.flags & SER_RS485_ENABLED);
  	int RTS_after_send = !!(uport->rs485.flags & SER_RS485_RTS_AFTER_SEND);
  
  	if (raise) {
  		if (rs485_on && !RTS_after_send) {
  			uart_set_mctrl(uport, TIOCM_DTR);
  			uart_clear_mctrl(uport, TIOCM_RTS);
  		} else {
  			uart_set_mctrl(uport, TIOCM_DTR | TIOCM_RTS);
  		}
  	} else {
  		unsigned int clear = TIOCM_DTR;
  
  		clear |= (!rs485_on || !RTS_after_send) ? TIOCM_RTS : 0;
  		uart_clear_mctrl(uport, clear);
  	}
  }
  
  /*
   * Startup the port.  This will be called once per open.  All calls
   * will be serialised by the per-port mutex.
   */
  static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
  		int init_hw)
  {
  	struct uart_port *uport = uart_port_check(state);
  	unsigned long page;
  	unsigned long flags = 0;
  	int retval = 0;
  
  	if (uport->type == PORT_UNKNOWN)
  		return 1;
  
  	/*
  	 * Make sure the device is in D0 state.
  	 */
  	uart_change_pm(state, UART_PM_STATE_ON);
  
  	/*
  	 * Initialise and allocate the transmit and temporary
  	 * buffer.
  	 */
  	page = get_zeroed_page(GFP_KERNEL);
  	if (!page)
  		return -ENOMEM;
  
  	uart_port_lock(state, flags);
  	if (!state->xmit.buf) {
  		state->xmit.buf = (unsigned char *) page;
  		uart_circ_clear(&state->xmit);
  		uart_port_unlock(uport, flags);
  	} else {
  		uart_port_unlock(uport, flags);
  		/*
  		 * Do not free() the page under the port lock, see
  		 * uart_shutdown().
  		 */
  		free_page(page);
  	}
  
  	retval = uport->ops->startup(uport);
  	if (retval == 0) {
  		if (uart_console(uport) && uport->cons->cflag) {
  			tty->termios.c_cflag = uport->cons->cflag;
  			uport->cons->cflag = 0;
  		}
  		/*
  		 * Initialise the hardware port settings.
  		 */
  		uart_change_speed(tty, state, NULL);
  
  		/*
  		 * Setup the RTS and DTR signals once the
  		 * port is open and ready to respond.
  		 */
  		if (init_hw && C_BAUD(tty))
  			uart_port_dtr_rts(uport, 1);
  	}
  
  	/*
  	 * This is to allow setserial on this port. People may want to set
  	 * port/irq/type and then reconfigure the port properly if it failed
  	 * now.
  	 */
  	if (retval && capable(CAP_SYS_ADMIN))
  		return 1;
  
  	return retval;
  }
  
  static int uart_startup(struct tty_struct *tty, struct uart_state *state,
  		int init_hw)
  {
  	struct tty_port *port = &state->port;
  	int retval;
  
  	if (tty_port_initialized(port))
  		return 0;
  
  	retval = uart_port_startup(tty, state, init_hw);
  	if (retval)
  		set_bit(TTY_IO_ERROR, &tty->flags);
  
  	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.
   *
   * uport == NULL if uart_port has already been removed
   */
  static void uart_shutdown(struct tty_struct *tty, struct uart_state *state)
  {
  	struct uart_port *uport = uart_port_check(state);
  	struct tty_port *port = &state->port;
  	unsigned long flags = 0;
  	char *xmit_buf = NULL;
  
  	/*
  	 * Set the TTY IO error marker
  	 */
  	if (tty)
  		set_bit(TTY_IO_ERROR, &tty->flags);
  
  	if (tty_port_initialized(port)) {
  		tty_port_set_initialized(port, 0);
  
  		/*
  		 * Turn off DTR and RTS early.
  		 */
  		if (uport && uart_console(uport) && tty)
  			uport->cons->cflag = tty->termios.c_cflag;
  
  		if (!tty || C_HUPCL(tty))
  			uart_port_dtr_rts(uport, 0);
  
  		uart_port_shutdown(port);
  	}
  
  	/*
  	 * It's possible for shutdown to be called after suspend if we get
  	 * a DCD drop (hangup) at just the right time.  Clear suspended bit so
  	 * we don't try to resume a port that has been shutdown.
  	 */
  	tty_port_set_suspended(port, 0);
  
  	/*
  	 * Do not free() the transmit buffer page under the port lock since
  	 * this can create various circular locking scenarios. For instance,
  	 * console driver may need to allocate/free a debug object, which
  	 * can endup in printk() recursion.
  	 */
  	uart_port_lock(state, flags);
  	xmit_buf = state->xmit.buf;
  	state->xmit.buf = NULL;
  	uart_port_unlock(uport, flags);
  
  	if (xmit_buf)
  		free_page((unsigned long)xmit_buf);
  }
  
  /**
   *	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;
  	unsigned int baud;
  	unsigned int altbaud;
  	int hung_up = 0;
  	upf_t flags = port->flags & UPF_SPD_MASK;
  
  	switch (flags) {
  	case UPF_SPD_HI:
  		altbaud = 57600;
  		break;
  	case UPF_SPD_VHI:
  		altbaud = 115200;
  		break;
  	case UPF_SPD_SHI:
  		altbaud = 230400;
  		break;
  	case UPF_SPD_WARP:
  		altbaud = 460800;
  		break;
  	default:
  		altbaud = 38400;
  		break;
  	}
  
  	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 (try == 0 && 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 range cannot be met then clip to
  		 * the nearest chip supported rate.
  		 */
  		if (!hung_up) {
  			if (baud <= min)
  				tty_termios_encode_baud_rate(termios,
  							min + 1, min + 1);
  			else
  				tty_termios_encode_baud_rate(termios,
  							max - 1, max - 1);
  		}
  	}
  	/* Should never happen */
  	WARN_ON(1);
  	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 = DIV_ROUND_CLOSEST(port->uartclk, 16 * baud);
  
  	return quot;
  }
  
  EXPORT_SYMBOL(uart_get_divisor);
  
  /* Caller holds port mutex */
  static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
  					struct ktermios *old_termios)
  {
  	struct uart_port *uport = uart_port_check(state);
  	struct ktermios *termios;
  	int hw_stopped;
  
  	/*
  	 * If we have no tty, termios, or the port does not exist,
  	 * then we can't set the parameters for this port.
  	 */
  	if (!tty || uport->type == PORT_UNKNOWN)
  		return;
  
  	termios = &tty->termios;
  	uport->ops->set_termios(uport, termios, old_termios);
  
  	/*
  	 * Set modem status enables based on termios cflag
  	 */
  	spin_lock_irq(&uport->lock);
  	if (termios->c_cflag & CRTSCTS)
  		uport->status |= UPSTAT_CTS_ENABLE;
  	else
  		uport->status &= ~UPSTAT_CTS_ENABLE;
  
  	if (termios->c_cflag & CLOCAL)
  		uport->status &= ~UPSTAT_DCD_ENABLE;
  	else
  		uport->status |= UPSTAT_DCD_ENABLE;
  
  	/* reset sw-assisted CTS flow control based on (possibly) new mode */
  	hw_stopped = uport->hw_stopped;
  	uport->hw_stopped = uart_softcts_mode(uport) &&
  				!(uport->ops->get_mctrl(uport) & TIOCM_CTS);
  	if (uport->hw_stopped) {
  		if (!hw_stopped)
  			uport->ops->stop_tx(uport);
  	} else {
  		if (hw_stopped)
  			__uart_start(tty);
  	}
  	spin_unlock_irq(&uport->lock);
  }
  
  static int uart_put_char(struct tty_struct *tty, unsigned char c)
  {
  	struct uart_state *state = tty->driver_data;
  	struct uart_port *port;
  	struct circ_buf *circ;
  	unsigned long flags;
  	int ret = 0;
  
  	circ = &state->xmit;
  	port = uart_port_lock(state, flags);
  	if (!circ->buf) {
  		uart_port_unlock(port, flags);
  		return 0;
  	}
  
  	if (port && uart_circ_chars_free(circ) != 0) {
  		circ->buf[circ->head] = c;
  		circ->head = (circ->head + 1) & (UART_XMIT_SIZE - 1);
  		ret = 1;
  	}
  	uart_port_unlock(port, flags);
  	return ret;
  }
  
  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) {
  		WARN_ON(1);
  		return -EL3HLT;
  	}
  
  	port = uart_port_lock(state, flags);
  	circ = &state->xmit;
  	if (!circ->buf) {
  		uart_port_unlock(port, flags);
  		return 0;
  	}
  
  	while (port) {
  		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;
  	}
  
  	__uart_start(tty);
  	uart_port_unlock(port, flags);
  	return ret;
  }
  
  static int uart_write_room(struct tty_struct *tty)
  {
  	struct uart_state *state = tty->driver_data;
  	struct uart_port *port;
  	unsigned long flags;
  	int ret;
  
  	port = uart_port_lock(state, flags);
  	ret = uart_circ_chars_free(&state->xmit);
  	uart_port_unlock(port, flags);
  	return ret;
  }
  
  static int uart_chars_in_buffer(struct tty_struct *tty)
  {
  	struct uart_state *state = tty->driver_data;
  	struct uart_port *port;
  	unsigned long flags;
  	int ret;
  
  	port = uart_port_lock(state, flags);
  	ret = uart_circ_chars_pending(&state->xmit);
  	uart_port_unlock(port, flags);
  	return ret;
  }
  
  static void uart_flush_buffer(struct tty_struct *tty)
  {
  	struct uart_state *state = tty->driver_data;
  	struct uart_port *port;
  	unsigned long flags;
  
  	/*
  	 * This means you called this function _after_ the port was
  	 * closed.  No cookie for you.
  	 */
  	if (!state) {
  		WARN_ON(1);
  		return;
  	}
  
  	pr_debug("uart_flush_buffer(%d) called\n", tty->index);
  
  	port = uart_port_lock(state, flags);
  	if (!port)
  		return;
  	uart_circ_clear(&state->xmit);
  	if (port->ops->flush_buffer)
  		port->ops->flush_buffer(port);
  	uart_port_unlock(port, flags);
  	tty_port_tty_wakeup(&state->port);
  }
  
  /*
   * 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;
  	unsigned long flags;
  
  	port = uart_port_ref(state);
  	if (!port)
  		return;
  
  	if (port->ops->send_xchar)
  		port->ops->send_xchar(port, ch);
  	else {
  		spin_lock_irqsave(&port->lock, flags);
  		port->x_char = ch;
  		if (ch)
  			port->ops->start_tx(port);
  		spin_unlock_irqrestore(&port->lock, flags);
  	}
  	uart_port_deref(port);
  }
  
  static void uart_throttle(struct tty_struct *tty)
  {
  	struct uart_state *state = tty->driver_data;
  	upstat_t mask = UPSTAT_SYNC_FIFO;
  	struct uart_port *port;
  
  	port = uart_port_ref(state);
  	if (!port)
  		return;
  
  	if (I_IXOFF(tty))
  		mask |= UPSTAT_AUTOXOFF;
  	if (C_CRTSCTS(tty))
  		mask |= UPSTAT_AUTORTS;
  
  	if (port->status & mask) {
  		port->ops->throttle(port);
  		mask &= ~port->status;
  	}
  
  	if (mask & UPSTAT_AUTORTS)
  		uart_clear_mctrl(port, TIOCM_RTS);
  
  	if (mask & UPSTAT_AUTOXOFF)
  		uart_send_xchar(tty, STOP_CHAR(tty));
  
  	uart_port_deref(port);
  }
  
  static void uart_unthrottle(struct tty_struct *tty)
  {
  	struct uart_state *state = tty->driver_data;
  	upstat_t mask = UPSTAT_SYNC_FIFO;
  	struct uart_port *port;
  
  	if (!state)
  		return;
  
  	port = uart_port_ref(state);
  	if (!port)
  		return;
  
  	if (I_IXOFF(tty))
  		mask |= UPSTAT_AUTOXOFF;
  	if (C_CRTSCTS(tty))
  		mask |= UPSTAT_AUTORTS;
  
  	if (port->status & mask) {
  		port->ops->unthrottle(port);
  		mask &= ~port->status;
  	}
  
  	if (mask & UPSTAT_AUTORTS)
  		uart_set_mctrl(port, TIOCM_RTS);
  
  	if (mask & UPSTAT_AUTOXOFF)
  		uart_send_xchar(tty, START_CHAR(tty));
  
  	uart_port_deref(port);
  }
  
  static int uart_get_info(struct tty_port *port, struct serial_struct *retinfo)
  {
  	struct uart_state *state = container_of(port, struct uart_state, port);
  	struct uart_port *uport;
  	int ret = -ENODEV;
  
  	memset(retinfo, 0, sizeof(*retinfo));
  
  	/*
  	 * Ensure the state we copy is consistent and no hardware changes
  	 * occur as we go
  	 */
  	mutex_lock(&port->mutex);
  	uport = uart_port_check(state);
  	if (!uport)
  		goto out;
  
  	retinfo->type	    = uport->type;
  	retinfo->line	    = uport->line;
  	retinfo->port	    = uport->iobase;
  	if (HIGH_BITS_OFFSET)
  		retinfo->port_high = (long) uport->iobase >> HIGH_BITS_OFFSET;
  	retinfo->irq		    = uport->irq;
  	retinfo->flags	    = (__force int)uport->flags;
  	retinfo->xmit_fifo_size  = uport->fifosize;
  	retinfo->baud_base	    = uport->uartclk / 16;
  	retinfo->close_delay	    = jiffies_to_msecs(port->close_delay) / 10;
  	retinfo->closing_wait    = port->closing_wait == ASYNC_CLOSING_WAIT_NONE ?
  				ASYNC_CLOSING_WAIT_NONE :
  				jiffies_to_msecs(port->closing_wait) / 10;
  	retinfo->custom_divisor  = uport->custom_divisor;
  	retinfo->hub6	    = uport->hub6;
  	retinfo->io_type         = uport->iotype;
  	retinfo->iomem_reg_shift = uport->regshift;
  	retinfo->iomem_base      = (void *)(unsigned long)uport->mapbase;
  
  	ret = 0;
  out:
  	mutex_unlock(&port->mutex);
  	return ret;
  }
  
  static int uart_get_info_user(struct tty_struct *tty,
  			 struct serial_struct *ss)
  {
  	struct uart_state *state = tty->driver_data;
  	struct tty_port *port = &state->port;
  
  	return uart_get_info(port, ss) < 0 ? -EIO : 0;
  }
  
  static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
  			 struct uart_state *state,
  			 struct serial_struct *new_info)
  {
  	struct uart_port *uport = uart_port_check(state);
  	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 (!uport)
  		return -EIO;
  
  	new_port = new_info->port;
  	if (HIGH_BITS_OFFSET)
  		new_port += (unsigned long) new_info->port_high << HIGH_BITS_OFFSET;
  
  	new_info->irq = irq_canonicalize(new_info->irq);
  	close_delay = msecs_to_jiffies(new_info->close_delay * 10);
  	closing_wait = new_info->closing_wait == ASYNC_CLOSING_WAIT_NONE ?
  			ASYNC_CLOSING_WAIT_NONE :
  			msecs_to_jiffies(new_info->closing_wait * 10);
  
  
  	change_irq  = !(uport->flags & UPF_FIXED_PORT)
  		&& new_info->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 = !(uport->flags & UPF_FIXED_PORT)
  		&& (new_port != uport->iobase ||
  		    (unsigned long)new_info->iomem_base != uport->mapbase ||
  		    new_info->hub6 != uport->hub6 ||
  		    new_info->io_type != uport->iotype ||
  		    new_info->iomem_reg_shift != uport->regshift ||
  		    new_info->type != uport->type);
  
  	old_flags = uport->flags;
  	new_flags = (__force upf_t)new_info->flags;
  	old_custom_divisor = uport->custom_divisor;
  
  	if (!capable(CAP_SYS_ADMIN)) {
  		retval = -EPERM;
  		if (change_irq || change_port ||
  		    (new_info->baud_base != uport->uartclk / 16) ||
  		    (close_delay != port->close_delay) ||
  		    (closing_wait != port->closing_wait) ||
  		    (new_info->xmit_fifo_size &&
  		     new_info->xmit_fifo_size != uport->fifosize) ||
  		    (((new_flags ^ old_flags) & ~UPF_USR_MASK) != 0))
  			goto exit;
  		uport->flags = ((uport->flags & ~UPF_USR_MASK) |
  			       (new_flags & UPF_USR_MASK));
  		uport->custom_divisor = new_info->custom_divisor;
  		goto check_and_exit;
  	}
  
  	/*
  	 * Ask the low level driver to verify the settings.
  	 */
  	if (uport->ops->verify_port)
  		retval = uport->ops->verify_port(uport, new_info);
  
  	if ((new_info->irq >= nr_irqs) || (new_info->irq < 0) ||
  	    (new_info->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 (tty_port_users(port) > 1)
  			goto exit;
  
  		/*
  		 * We need to shutdown the serial port at the old
  		 * port/type/irq combination.
  		 */
  		uart_shutdown(tty, state);
  	}
  
  	if (change_port) {
  		unsigned long old_iobase, old_mapbase;
  		unsigned int old_type, old_iotype, old_hub6, old_shift;
  
  		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 && uport->ops->release_port)
  			uport->ops->release_port(uport);
  
  		uport->iobase = new_port;
  		uport->type = new_info->type;
  		uport->hub6 = new_info->hub6;
  		uport->iotype = new_info->io_type;
  		uport->regshift = new_info->iomem_reg_shift;
  		uport->mapbase = (unsigned long)new_info->iomem_base;
  
  		/*
  		 * Claim and map the new regions
  		 */
  		if (uport->type != PORT_UNKNOWN && uport->ops->request_port) {
  			retval = uport->ops->request_port(uport);
  		} 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) {
  			uport->iobase = old_iobase;
  			uport->type = old_type;
  			uport->hub6 = old_hub6;
  			uport->iotype = old_iotype;
  			uport->regshift = old_shift;
  			uport->mapbase = old_mapbase;
  
  			if (old_type != PORT_UNKNOWN) {
  				retval = uport->ops->request_port(uport);
  				/*
  				 * If we failed to restore the old settings,
  				 * we fail like this.
  				 */
  				if (retval)
  					uport->type = PORT_UNKNOWN;
  
  				/*
  				 * We failed anyway.
  				 */
  				retval = -EBUSY;
  			}
  
  			/* Added to return the correct error -Ram Gupta */
  			goto exit;
  		}
  	}
  
  	if (change_irq)
  		uport->irq      = new_info->irq;
  	if (!(uport->flags & UPF_FIXED_PORT))
  		uport->uartclk  = new_info->baud_base * 16;
  	uport->flags            = (uport->flags & ~UPF_CHANGE_MASK) |
  				 (new_flags & UPF_CHANGE_MASK);
  	uport->custom_divisor   = new_info->custom_divisor;
  	port->close_delay     = close_delay;
  	port->closing_wait    = closing_wait;
  	if (new_info->xmit_fifo_size)
  		uport->fifosize = new_info->xmit_fifo_size;
  	port->low_latency = (uport->flags & UPF_LOW_LATENCY) ? 1 : 0;
  
   check_and_exit:
  	retval = 0;
  	if (uport->type == PORT_UNKNOWN)
  		goto exit;
  	if (tty_port_initialized(port)) {
  		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.
  			 */
  			if (uport->flags & UPF_SPD_MASK) {
  				dev_notice_ratelimited(uport->dev,
  				       "%s sets custom speed on %s. This is deprecated.\n",
  				      current->comm,
  				      tty_name(port->tty));
  			}
  			uart_change_speed(tty, state, NULL);
  		}
  	} else {
  		retval = uart_startup(tty, state, 1);
  		if (retval == 0)
  			tty_port_set_initialized(port, true);
  		if (retval > 0)
  			retval = 0;
  	}
   exit:
  	return retval;
  }
  
  static int uart_set_info_user(struct tty_struct *tty, struct serial_struct *ss)
  {
  	struct uart_state *state = tty->driver_data;
  	struct tty_port *port = &state->port;
  	int retval;
  
  	down_write(&tty->termios_rwsem);
  	/*
  	 * This semaphore protects port->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(&port->mutex);
  	retval = uart_set_info(tty, port, state, ss);
  	mutex_unlock(&port->mutex);
  	up_write(&tty->termios_rwsem);
  	return retval;
  }
  
  /**
   *	uart_get_lsr_info	-	get line status register info
   *	@tty: tty associated with the UART
   *	@state: UART being queried
   *	@value: returned modem value
   */
  static int uart_get_lsr_info(struct tty_struct *tty,
  			struct uart_state *state, unsigned int __user *value)
  {
  	struct uart_port *uport = uart_port_check(state);
  	unsigned int result;
  
  	result = uport->ops->tx_empty(uport);
  
  	/*
  	 * 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 (uport->x_char ||
  	    ((uart_circ_chars_pending(&state->xmit) > 0) &&
  	     !uart_tx_stopped(uport)))
  		result &= ~TIOCSER_TEMT;
  
  	return put_user(result, value);
  }
  
  static int uart_tiocmget(struct tty_struct *tty)
  {
  	struct uart_state *state = tty->driver_data;
  	struct tty_port *port = &state->port;
  	struct uart_port *uport;
  	int result = -EIO;
  
  	mutex_lock(&port->mutex);
  	uport = uart_port_check(state);
  	if (!uport)
  		goto out;
  
  	if (!tty_io_error(tty)) {
  		result = uport->mctrl;
  		spin_lock_irq(&uport->lock);
  		result |= uport->ops->get_mctrl(uport);
  		spin_unlock_irq(&uport->lock);
  	}
  out:
  	mutex_unlock(&port->mutex);
  	return result;
  }
  
  static int
  uart_tiocmset(struct tty_struct *tty, unsigned int set, unsigned int clear)
  {
  	struct uart_state *state = tty->driver_data;
  	struct tty_port *port = &state->port;
  	struct uart_port *uport;
  	int ret = -EIO;
  
  	mutex_lock(&port->mutex);
  	uport = uart_port_check(state);
  	if (!uport)
  		goto out;
  
  	if (!tty_io_error(tty)) {
  		uart_update_mctrl(uport, set, clear);
  		ret = 0;
  	}
  out:
  	mutex_unlock(&port->mutex);
  	return ret;
  }
  
  static int uart_break_ctl(struct tty_struct *tty, int break_state)
  {
  	struct uart_state *state = tty->driver_data;
  	struct tty_port *port = &state->port;
  	struct uart_port *uport;
  	int ret = -EIO;
  
  	mutex_lock(&port->mutex);
  	uport = uart_port_check(state);
  	if (!uport)
  		goto out;
  
  	if (uport->type != PORT_UNKNOWN)
  		uport->ops->break_ctl(uport, break_state);
  	ret = 0;
  out:
  	mutex_unlock(&port->mutex);
  	return ret;
  }
  
  static int uart_do_autoconfig(struct tty_struct *tty,struct uart_state *state)
  {
  	struct tty_port *port = &state->port;
  	struct uart_port *uport;
  	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(&port->mutex))
  		return -ERESTARTSYS;
  
  	uport = uart_port_check(state);
  	if (!uport) {
  		ret = -EIO;
  		goto out;
  	}
  
  	ret = -EBUSY;
  	if (tty_port_users(port) == 1) {
  		uart_shutdown(tty, state);
  
  		/*
  		 * If we already have a port type configured,
  		 * we must release its resources.
  		 */
  		if (uport->type != PORT_UNKNOWN && uport->ops->release_port)
  			uport->ops->release_port(uport);
  
  		flags = UART_CONFIG_TYPE;
  		if (uport->flags & UPF_AUTO_IRQ)
  			flags |= UART_CONFIG_IRQ;
  
  		/*
  		 * This will claim the ports resources if
  		 * a port is found.
  		 */
  		uport->ops->config_port(uport, flags);
  
  		ret = uart_startup(tty, state, 1);
  		if (ret == 0)
  			tty_port_set_initialized(port, true);
  		if (ret > 0)
  			ret = 0;
  	}
  out:
  	mutex_unlock(&port->mutex);
  	return ret;
  }
  
  static void uart_enable_ms(struct uart_port *uport)
  {
  	/*
  	 * Force modem status interrupts on
  	 */
  	if (uport->ops->enable_ms)
  		uport->ops->enable_ms(uport);
  }
  
  /*
   * 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
   *
   * FIXME: This wants extracting into a common all driver implementation
   * of TIOCMWAIT using tty_port.
   */
  static int uart_wait_modem_status(struct uart_state *state, unsigned long arg)
  {
  	struct uart_port *uport;
  	struct tty_port *port = &state->port;
  	DECLARE_WAITQUEUE(wait, current);
  	struct uart_icount cprev, cnow;
  	int ret;
  
  	/*
  	 * note the counters on entry
  	 */
  	uport = uart_port_ref(state);
  	if (!uport)
  		return -EIO;
  	spin_lock_irq(&uport->lock);
  	memcpy(&cprev, &uport->icount, sizeof(struct uart_icount));
  	uart_enable_ms(uport);
  	spin_unlock_irq(&uport->lock);
  
  	add_wait_queue(&port->delta_msr_wait, &wait);
  	for (;;) {
  		spin_lock_irq(&uport->lock);
  		memcpy(&cnow, &uport->icount, sizeof(struct uart_icount));
  		spin_unlock_irq(&uport->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;
  	}
  	__set_current_state(TASK_RUNNING);
  	remove_wait_queue(&port->delta_msr_wait, &wait);
  	uart_port_deref(uport);
  
  	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_icount(struct tty_struct *tty,
  			  struct serial_icounter_struct *icount)
  {
  	struct uart_state *state = tty->driver_data;
  	struct uart_icount cnow;
  	struct uart_port *uport;
  
  	uport = uart_port_ref(state);
  	if (!uport)
  		return -EIO;
  	spin_lock_irq(&uport->lock);
  	memcpy(&cnow, &uport->icount, sizeof(struct uart_icount));
  	spin_unlock_irq(&uport->lock);
  	uart_port_deref(uport);
  
  	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 0;
  }
  
  static int uart_get_rs485_config(struct uart_port *port,
  			 struct serial_rs485 __user *rs485)
  {
  	unsigned long flags;
  	struct serial_rs485 aux;
  
  	spin_lock_irqsave(&port->lock, flags);
  	aux = port->rs485;
  	spin_unlock_irqrestore(&port->lock, flags);
  
  	if (copy_to_user(rs485, &aux, sizeof(aux)))
  		return -EFAULT;
  
  	return 0;
  }
  
  static int uart_set_rs485_config(struct uart_port *port,
  			 struct serial_rs485 __user *rs485_user)
  {
  	struct serial_rs485 rs485;
  	int ret;
  	unsigned long flags;
  
  	if (!port->rs485_config)
  		return -ENOIOCTLCMD;
  
  	if (copy_from_user(&rs485, rs485_user, sizeof(*rs485_user)))
  		return -EFAULT;
  
  	spin_lock_irqsave(&port->lock, flags);
  	ret = port->rs485_config(port, &rs485);
  	spin_unlock_irqrestore(&port->lock, flags);
  	if (ret)
  		return ret;
  
  	if (copy_to_user(rs485_user, &port->rs485, sizeof(port->rs485)))
  		return -EFAULT;
  
  	return 0;
  }
  
  static int uart_get_iso7816_config(struct uart_port *port,
  				   struct serial_iso7816 __user *iso7816)
  {
  	unsigned long flags;
  	struct serial_iso7816 aux;
  
  	if (!port->iso7816_config)
  		return -ENOIOCTLCMD;
  
  	spin_lock_irqsave(&port->lock, flags);
  	aux = port->iso7816;
  	spin_unlock_irqrestore(&port->lock, flags);
  
  	if (copy_to_user(iso7816, &aux, sizeof(aux)))
  		return -EFAULT;
  
  	return 0;
  }
  
  static int uart_set_iso7816_config(struct uart_port *port,
  				   struct serial_iso7816 __user *iso7816_user)
  {
  	struct serial_iso7816 iso7816;
  	int i, ret;
  	unsigned long flags;
  
  	if (!port->iso7816_config)
  		return -ENOIOCTLCMD;
  
  	if (copy_from_user(&iso7816, iso7816_user, sizeof(*iso7816_user)))
  		return -EFAULT;
  
  	/*
  	 * There are 5 words reserved for future use. Check that userspace
  	 * doesn't put stuff in there to prevent breakages in the future.
  	 */
  	for (i = 0; i < 5; i++)
  		if (iso7816.reserved[i])
  			return -EINVAL;
  
  	spin_lock_irqsave(&port->lock, flags);
  	ret = port->iso7816_config(port, &iso7816);
  	spin_unlock_irqrestore(&port->lock, flags);
  	if (ret)
  		return ret;
  
  	if (copy_to_user(iso7816_user, &port->iso7816, sizeof(port->iso7816)))
  		return -EFAULT;
  
  	return 0;
  }
  
  /*
   * Called via sys_ioctl.  We can use spin_lock_irq() here.
   */
  static int
  uart_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
  {
  	struct uart_state *state = tty->driver_data;
  	struct tty_port *port = &state->port;
  	struct uart_port *uport;
  	void __user *uarg = (void __user *)arg;
  	int ret = -ENOIOCTLCMD;
  
  
  	/*
  	 * These ioctls don't rely on the hardware to be present.
  	 */
  	switch (cmd) {
  	case TIOCSERCONFIG:
  		down_write(&tty->termios_rwsem);
  		ret = uart_do_autoconfig(tty, state);
  		up_write(&tty->termios_rwsem);
  		break;
  	}
  
  	if (ret != -ENOIOCTLCMD)
  		goto out;
  
  	if (tty_io_error(tty)) {
  		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;
  	}
  
  	if (ret != -ENOIOCTLCMD)
  		goto out;
  
  	mutex_lock(&port->mutex);
  	uport = uart_port_check(state);
  
  	if (!uport || tty_io_error(tty)) {
  		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(tty, state, uarg);
  		break;
  
  	case TIOCGRS485:
  		ret = uart_get_rs485_config(uport, uarg);
  		break;
  
  	case TIOCSRS485:
  		ret = uart_set_rs485_config(uport, uarg);
  		break;
  
  	case TIOCSISO7816:
  		ret = uart_set_iso7816_config(state->uart_port, uarg);
  		break;
  
  	case TIOCGISO7816:
  		ret = uart_get_iso7816_config(state->uart_port, uarg);
  		break;
  	default:
  		if (uport->ops->ioctl)
  			ret = uport->ops->ioctl(uport, cmd, arg);
  		break;
  	}
  out_up:
  	mutex_unlock(&port->mutex);
  out:
  	return ret;
  }
  
  static void uart_set_ldisc(struct tty_struct *tty)
  {
  	struct uart_state *state = tty->driver_data;
  	struct uart_port *uport;
  
  	mutex_lock(&state->port.mutex);
  	uport = uart_port_check(state);
  	if (uport && uport->ops->set_ldisc)
  		uport->ops->set_ldisc(uport, &tty->termios);
  	mutex_unlock(&state->port.mutex);
  }
  
  static void uart_set_termios(struct tty_struct *tty,
  						struct ktermios *old_termios)
  {
  	struct uart_state *state = tty->driver_data;
  	struct uart_port *uport;
  	unsigned int cflag = tty->termios.c_cflag;
  	unsigned int iflag_mask = IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK;
  	bool sw_changed = false;
  
  	mutex_lock(&state->port.mutex);
  	uport = uart_port_check(state);
  	if (!uport)
  		goto out;
  
  	/*
  	 * Drivers doing software flow control also need to know
  	 * about changes to these input settings.
  	 */
  	if (uport->flags & UPF_SOFT_FLOW) {
  		iflag_mask |= IXANY|IXON|IXOFF;
  		sw_changed =
  		   tty->termios.c_cc[VSTART] != old_termios->c_cc[VSTART] ||
  		   tty->termios.c_cc[VSTOP] != old_termios->c_cc[VSTOP];
  	}
  
  	/*
  	 * 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
  	 */
  	if ((cflag ^ old_termios->c_cflag) == 0 &&
  	    tty->termios.c_ospeed == old_termios->c_ospeed &&
  	    tty->termios.c_ispeed == old_termios->c_ispeed &&
  	    ((tty->termios.c_iflag ^ old_termios->c_iflag) & iflag_mask) == 0 &&
  	    !sw_changed) {
  		goto out;
  	}
  
  	uart_change_speed(tty, state, old_termios);
  	/* reload cflag from termios; port driver may have overriden flags */
  	cflag = tty->termios.c_cflag;
  
  	/* Handle transition to B0 status */
  	if ((old_termios->c_cflag & CBAUD) && !(cflag & CBAUD))
  		uart_clear_mctrl(uport, TIOCM_RTS | TIOCM_DTR);
  	/* Handle transition away from B0 status */
  	else if (!(old_termios->c_cflag & CBAUD) && (cflag & CBAUD)) {
  		unsigned int mask = TIOCM_DTR;
  		if (!(cflag & CRTSCTS) || !tty_throttled(tty))
  			mask |= TIOCM_RTS;
  		uart_set_mctrl(uport, mask);
  	}
  out:
  	mutex_unlock(&state->port.mutex);
  }
  
  /*
   * Calls to uart_close() are serialised via the tty_lock in
   *   drivers/tty/tty_io.c:tty_release()
   *   drivers/tty/tty_io.c:do_tty_hangup()
   */
  static void uart_close(struct tty_struct *tty, struct file *filp)
  {
  	struct uart_state *state = tty->driver_data;
  
  	if (!state) {
  		struct uart_driver *drv = tty->driver->driver_state;
  		struct tty_port *port;
  
  		state = drv->state + tty->index;
  		port = &state->port;
  		spin_lock_irq(&port->lock);
  		--port->count;
  		spin_unlock_irq(&port->lock);
  		return;
  	}
  
  	pr_debug("uart_close(%d) called\n", tty->index);
  
  	tty_port_close(tty->port, tty, filp);
  }
  
  static void uart_tty_port_shutdown(struct tty_port *port)
  {
  	struct uart_state *state = container_of(port, struct uart_state, port);
  	struct uart_port *uport = uart_port_check(state);
  
  	/*
  	 * At this point, we stop accepting input.  To do this, we
  	 * disable the receive line status interrupts.
  	 */
  	if (WARN(!uport, "detached port still initialized!\n"))
  		return;
  
  	spin_lock_irq(&uport->lock);
  	uport->ops->stop_rx(uport);
  	spin_unlock_irq(&uport->lock);
  
  	uart_port_shutdown(port);
  
  	/*
  	 * It's possible for shutdown to be called after suspend if we get
  	 * a DCD drop (hangup) at just the right time.  Clear suspended bit so
  	 * we don't try to resume a port that has been shutdown.
  	 */
  	tty_port_set_suspended(port, 0);
  
  	uart_change_pm(state, UART_PM_STATE_OFF);
  
  }
  
  static void uart_wait_until_sent(struct tty_struct *tty, int timeout)
  {
  	struct uart_state *state = tty->driver_data;
  	struct uart_port *port;
  	unsigned long char_time, expire;
  
  	port = uart_port_ref(state);
  	if (!port)
  		return;
  
  	if (port->type == PORT_UNKNOWN || port->fifosize == 0) {
  		uart_port_deref(port);
  		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;
  	}
  	uart_port_deref(port);
  }
  
  /*
   * Calls to uart_hangup() are serialised by the tty_lock in
   *   drivers/tty/tty_io.c:do_tty_hangup()
   * This runs from a workqueue and can sleep for a _short_ time only.
   */
  static void uart_hangup(struct tty_struct *tty)
  {
  	struct uart_state *state = tty->driver_data;
  	struct tty_port *port = &state->port;
  	struct uart_port *uport;
  	unsigned long flags;
  
  	pr_debug("uart_hangup(%d)\n", tty->index);
  
  	mutex_lock(&port->mutex);
  	uport = uart_port_check(state);
  	WARN(!uport, "hangup of detached port!\n");
  
  	if (tty_port_active(port)) {
  		uart_flush_buffer(tty);
  		uart_shutdown(tty, state);
  		spin_lock_irqsave(&port->lock, flags);
  		port->count = 0;
  		spin_unlock_irqrestore(&port->lock, flags);
  		tty_port_set_active(port, 0);
  		tty_port_tty_set(port, NULL);
  		if (uport && !uart_console(uport))
  			uart_change_pm(state, UART_PM_STATE_OFF);
  		wake_up_interruptible(&port->open_wait);
  		wake_up_interruptible(&port->delta_msr_wait);
  	}
  	mutex_unlock(&port->mutex);
  }
  
  /* uport == NULL if uart_port has already been removed */
  static void uart_port_shutdown(struct tty_port *port)
  {
  	struct uart_state *state = container_of(port, struct uart_state, port);
  	struct uart_port *uport = uart_port_check(state);
  
  	/*
  	 * 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(&port->delta_msr_wait);
  
  	/*
  	 * Free the IRQ and disable the port.
  	 */
  	if (uport)
  		uport->ops->shutdown(uport);
  
  	/*
  	 * Ensure that the IRQ handler isn't running on another CPU.
  	 */
  	if (uport)
  		synchronize_irq(uport->irq);
  }
  
  static int uart_carrier_raised(struct tty_port *port)
  {
  	struct uart_state *state = container_of(port, struct uart_state, port);
  	struct uart_port *uport;
  	int mctrl;
  
  	uport = uart_port_ref(state);
  	/*
  	 * Should never observe uport == NULL since checks for hangup should
  	 * abort the tty_port_block_til_ready() loop before checking for carrier
  	 * raised -- but report carrier raised if it does anyway so open will
  	 * continue and not sleep
  	 */
  	if (WARN_ON(!uport))
  		return 1;
  	spin_lock_irq(&uport->lock);
  	uart_enable_ms(uport);
  	mctrl = uport->ops->get_mctrl(uport);
  	spin_unlock_irq(&uport->lock);
  	uart_port_deref(uport);
  	if (mctrl & TIOCM_CAR)
  		return 1;
  	return 0;
  }
  
  static void uart_dtr_rts(struct tty_port *port, int raise)
  {
  	struct uart_state *state = container_of(port, struct uart_state, port);
  	struct uart_port *uport;
  
  	uport = uart_port_ref(state);
  	if (!uport)
  		return;
  	uart_port_dtr_rts(uport, raise);
  	uart_port_deref(uport);
  }
  
  /*
   * Calls to uart_open are serialised by the tty_lock in
   *   drivers/tty/tty_io.c:tty_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 = tty->driver->driver_state;
  	int retval, line = tty->index;
  	struct uart_state *state = drv->state + line;
  
  	tty->driver_data = state;
  
  	retval = tty_port_open(&state->port, tty, filp);
  	if (retval > 0)
  		retval = 0;
  
  	return retval;
  }
  
  static int uart_port_activate(struct tty_port *port, struct tty_struct *tty)
  {
  	struct uart_state *state = container_of(port, struct uart_state, port);
  	struct uart_port *uport;
  
  	uport = uart_port_check(state);
  	if (!uport || uport->flags & UPF_DEAD)
  		return -ENXIO;
  
  	port->low_latency = (uport->flags & UPF_LOW_LATENCY) ? 1 : 0;
  
  	/*
  	 * Start up the serial port.
  	 */
  	return uart_startup(tty, state, 0);
  }
  
  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 void uart_line_info(struct seq_file *m, struct uart_driver *drv, int i)
  {
  	struct uart_state *state = drv->state + i;
  	struct tty_port *port = &state->port;
  	enum uart_pm_state pm_state;
  	struct uart_port *uport;
  	char stat_buf[32];
  	unsigned int status;
  	int mmio;
  
  	mutex_lock(&port->mutex);
  	uport = uart_port_check(state);
  	if (!uport)
  		goto out;
  
  	mmio = uport->iotype >= UPIO_MEM;
  	seq_printf(m, "%d: uart:%s %s%08llX irq:%d",
  			uport->line, uart_type(uport),
  			mmio ? "mmio:0x" : "port:",
  			mmio ? (unsigned long long)uport->mapbase
  			     : (unsigned long long)uport->iobase,
  			uport->irq);
  
  	if (uport->type == PORT_UNKNOWN) {
  		seq_putc(m, '\n');
  		goto out;
  	}
  
  	if (capable(CAP_SYS_ADMIN)) {
  		pm_state = state->pm_state;
  		if (pm_state != UART_PM_STATE_ON)
  			uart_change_pm(state, UART_PM_STATE_ON);
  		spin_lock_irq(&uport->lock);
  		status = uport->ops->get_mctrl(uport);
  		spin_unlock_irq(&uport->lock);
  		if (pm_state != UART_PM_STATE_ON)
  			uart_change_pm(state, pm_state);
  
  		seq_printf(m, " tx:%d rx:%d",
  				uport->icount.tx, uport->icount.rx);
  		if (uport->icount.frame)
  			seq_printf(m, " fe:%d",	uport->icount.frame);
  		if (uport->icount.parity)
  			seq_printf(m, " pe:%d",	uport->icount.parity);
  		if (uport->icount.brk)
  			seq_printf(m, " brk:%d", uport->icount.brk);
  		if (uport->icount.overrun)
  			seq_printf(m, " oe:%d", uport->icount.overrun);
  		if (uport->icount.buf_overrun)
  			seq_printf(m, " bo:%d", uport->icount.buf_overrun);
  
  #define INFOBIT(bit, str) \
  	if (uport->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] = ' ';
  
  		seq_puts(m, stat_buf);
  	}
  	seq_putc(m, '\n');
  #undef STATBIT
  #undef INFOBIT
  out:
  	mutex_unlock(&port->mutex);
  }
  
  static int uart_proc_show(struct seq_file *m, void *v)
  {
  	struct tty_driver *ttydrv = m->private;
  	struct uart_driver *drv = ttydrv->driver_state;
  	int i;
  
  	seq_printf(m, "serinfo:1.0 driver%s%s revision:%s\n", "", "", "");
  	for (i = 0; i < drv->nr; i++)
  		uart_line_info(m, drv, i);
  	return 0;
  }
  #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
   *	@putchar: 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_earlycon - Parse earlycon options
   *	@p:	  ptr to 2nd field (ie., just beyond '<name>,')
   *	@iotype:  ptr for decoded iotype (out)
   *	@addr:    ptr for decoded mapbase/iobase (out)
   *	@options: ptr for <options> field; NULL if not present (out)
   *
   *	Decodes earlycon kernel command line parameters of the form
   *	   earlycon=<name>,io|mmio|mmio16|mmio32|mmio32be|mmio32native,<addr>,<options>
   *	   console=<name>,io|mmio|mmio16|mmio32|mmio32be|mmio32native,<addr>,<options>
   *
   *	The optional form
   *	   earlycon=<name>,0x<addr>,<options>
   *	   console=<name>,0x<addr>,<options>
   *	is also accepted; the returned @iotype will be UPIO_MEM.
   *
   *	Returns 0 on success or -EINVAL on failure
   */
  int uart_parse_earlycon(char *p, unsigned char *iotype, resource_size_t *addr,
  			char **options)
  {
  	if (strncmp(p, "mmio,", 5) == 0) {
  		*iotype = UPIO_MEM;
  		p += 5;
  	} else if (strncmp(p, "mmio16,", 7) == 0) {
  		*iotype = UPIO_MEM16;
  		p += 7;
  	} else if (strncmp(p, "mmio32,", 7) == 0) {
  		*iotype = UPIO_MEM32;
  		p += 7;
  	} else if (strncmp(p, "mmio32be,", 9) == 0) {
  		*iotype = UPIO_MEM32BE;
  		p += 9;
  	} else if (strncmp(p, "mmio32native,", 13) == 0) {
  		*iotype = IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) ?
  			UPIO_MEM32BE : UPIO_MEM32;
  		p += 13;
  	} else if (strncmp(p, "io,", 3) == 0) {
  		*iotype = UPIO_PORT;
  		p += 3;
  	} else if (strncmp(p, "0x", 2) == 0) {
  		*iotype = UPIO_MEM;
  	} else {
  		return -EINVAL;
  	}
  
  	/*
  	 * Before you replace it with kstrtoull(), think about options separator
  	 * (',') it will not tolerate
  	 */
  	*addr = simple_strtoull(p, NULL, 0);
  	p = strchr(p, ',');
  	if (p)
  		p++;
  
  	*options = p;
  	return 0;
  }
  EXPORT_SYMBOL_GPL(uart_parse_earlycon);
  
  /**
   *	uart_parse_options - Parse serial port baud/parity/bits/flow control.
   *	@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(const char *options, int *baud, int *parity,
  		   int *bits, int *flow)
  {
  	const 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);
  
  /**
   *	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;
  
  	/*
  	 * Ensure that the serial console lock is initialised
  	 * early.
  	 * 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);
  	}
  
  	memset(&termios, 0, sizeof(struct ktermios));
  
  	termios.c_cflag |= CREAD | HUPCL | CLOCAL;
  	tty_termios_encode_baud_rate(&termios, baud, baud);
  
  	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 */
  
  /**
   * uart_change_pm - set power state of the port
   *
   * @state: port descriptor
   * @pm_state: new state
   *
   * Locking: port->mutex has to be held
   */
  static void uart_change_pm(struct uart_state *state,
  			   enum uart_pm_state pm_state)
  {
  	struct uart_port *port = uart_port_check(state);
  
  	if (state->pm_state != pm_state) {
  		if (port && 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;
  	struct tty_driver *tty_drv = match->driver->tty_driver;
  	dev_t devt = MKDEV(tty_drv->major, tty_drv->minor_start) +
  		match->port->line;
  
  	return dev->devt == devt; /* Actually, only one tty per port */
  }
  
  int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
  {
  	struct uart_state *state = drv->state + uport->line;
  	struct tty_port *port = &state->port;
  	struct device *tty_dev;
  	struct uart_match match = {uport, drv};
  
  	mutex_lock(&port->mutex);
  
  	tty_dev = device_find_child(uport->dev, &match, serial_match_port);
  	if (tty_dev && device_may_wakeup(tty_dev)) {
  		enable_irq_wake(uport->irq);
  		put_device(tty_dev);
  		mutex_unlock(&port->mutex);
  		return 0;
  	}
  	put_device(tty_dev);
  
  	/* Nothing to do if the console is not suspending */
  	if (!console_suspend_enabled && uart_console(uport))
  		goto unlock;
  
  	uport->suspended = 1;
  
  	if (tty_port_initialized(port)) {
  		const struct uart_ops *ops = uport->ops;
  		int tries;
  
  		tty_port_set_suspended(port, 1);
  		tty_port_set_initialized(port, 0);
  
  		spin_lock_irq(&uport->lock);
  		ops->stop_tx(uport);
  		ops->set_mctrl(uport, 0);
  		ops->stop_rx(uport);
  		spin_unlock_irq(&uport->lock);
  
  		/*
  		 * Wait for the transmitter to empty.
  		 */
  		for (tries = 3; !ops->tx_empty(uport) && tries; tries--)
  			msleep(10);
  		if (!tries)
  			dev_err(uport->dev, "%s: Unable to drain transmitter\n",
  				uport->name);
  
  		ops->shutdown(uport);
  	}
  
  	/*
  	 * Disable the console device before suspending.
  	 */
  	if (uart_console(uport))
  		console_stop(uport->cons);
  
  	uart_change_pm(state, UART_PM_STATE_OFF);
  unlock:
  	mutex_unlock(&port->mutex);
  
  	return 0;
  }
  
  int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
  {
  	struct uart_state *state = drv->state + uport->line;
  	struct tty_port *port = &state->port;
  	struct device *tty_dev;
  	struct uart_match match = {uport, drv};
  	struct ktermios termios;
  
  	mutex_lock(&port->mutex);
  
  	tty_dev = device_find_child(uport->dev, &match, serial_match_port);
  	if (!uport->suspended && device_may_wakeup(tty_dev)) {
  		if (irqd_is_wakeup_set(irq_get_irq_data((uport->irq))))
  			disable_irq_wake(uport->irq);
  		put_device(tty_dev);
  		mutex_unlock(&port->mutex);
  		return 0;
  	}
  	put_device(tty_dev);
  	uport->suspended = 0;
  
  	/*
  	 * Re-enable the console device after suspending.
  	 */
  	if (uart_console(uport)) {
  		/*
  		 * First try to use the console cflag setting.
  		 */
  		memset(&termios, 0, sizeof(struct ktermios));
  		termios.c_cflag = uport->cons->cflag;
  
  		/*
  		 * If that's unset, use the tty termios setting.
  		 */
  		if (port->tty && termios.c_cflag == 0)
  			termios = port->tty->termios;
  
  		if (console_suspend_enabled)
  			uart_change_pm(state, UART_PM_STATE_ON);
  		uport->ops->set_termios(uport, &termios, NULL);
  		if (console_suspend_enabled)
  			console_start(uport->cons);
  	}
  
  	if (tty_port_suspended(port)) {
  		const struct uart_ops *ops = uport->ops;
  		int ret;
  
  		uart_change_pm(state, UART_PM_STATE_ON);
  		spin_lock_irq(&uport->lock);
  		ops->set_mctrl(uport, 0);
  		spin_unlock_irq(&uport->lock);
  		if (console_suspend_enabled || !uart_console(uport)) {
  			/* Protected by port mutex for now */
  			struct tty_struct *tty = port->tty;
  			ret = ops->startup(uport);
  			if (ret == 0) {
  				if (tty)
  					uart_change_speed(tty, state, NULL);
  				spin_lock_irq(&uport->lock);
  				ops->set_mctrl(uport, uport->mctrl);
  				ops->start_tx(uport);
  				spin_unlock_irq(&uport->lock);
  				tty_port_set_initialized(port, 1);
  			} 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(tty, state);
  			}
  		}
  
  		tty_port_set_suspended(port, 0);
  	}
  
  	mutex_unlock(&port->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%lx", port->iobase);
  		break;
  	case UPIO_HUB6:
  		snprintf(address, sizeof(address),
  			 "I/O 0x%lx offset 0x%x", port->iobase, port->hub6);
  		break;
  	case UPIO_MEM:
  	case UPIO_MEM16:
  	case UPIO_MEM32:
  	case UPIO_MEM32BE:
  	case UPIO_AU:
  	case UPIO_TSI:
  		snprintf(address, sizeof(address),
  			 "MMIO 0x%llx", (unsigned long long)port->mapbase);
  		break;
  	default:
  		strlcpy(address, "*unknown*", sizeof(address));
  		break;
  	}
  
  	pr_info("%s%s%s at %s (irq = %d, base_baud = %d) is a %s\n",
  	       port->dev ? dev_name(port->dev) : "",
  	       port->dev ? ": " : "",
  	       port->name,
  	       address, port->irq, port->uartclk / 16, 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 = 0;
  	if (port->flags & UPF_AUTO_IRQ)
  		flags |= UART_CONFIG_IRQ;
  	if (port->flags & UPF_BOOT_AUTOCONF) {
  		if (!(port->flags & UPF_FIXED_TYPE)) {
  			port->type = PORT_UNKNOWN;
  			flags |= UART_CONFIG_TYPE;
  		}
  		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, UART_PM_STATE_ON);
  
  		/*
  		 * 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, UART_PM_STATE_OFF);
  	}
  }
  
  #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 tty_port *tport;
  	struct uart_port *port;
  	int baud = 9600;
  	int bits = 8;
  	int parity = 'n';
  	int flow = 'n';
  	int ret = 0;
  
  	tport = &state->port;
  	mutex_lock(&tport->mutex);
  
  	port = uart_port_check(state);
  	if (!port || !(port->ops->poll_get_char && port->ops->poll_put_char)) {
  		ret = -1;
  		goto out;
  	}
  
  	if (port->ops->poll_init) {
  		/*
  		 * We don't set initialized as we only initialized the hw,
  		 * e.g. state->xmit is still uninitialized.
  		 */
  		if (!tty_port_initialized(tport))
  			ret = port->ops->poll_init(port);
  	}
  
  	if (!ret && options) {
  		uart_parse_options(options, &baud, &parity, &bits, &flow);
  		ret = uart_set_options(port, NULL, baud, parity, bits, flow);
  	}
  out:
  	mutex_unlock(&tport->mutex);
  	return ret;
  }
  
  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;
  	int ret = -1;
  
  	port = uart_port_ref(state);
  	if (port) {
  		ret = port->ops->poll_get_char(port);
  		uart_port_deref(port);
  	}
  
  	return ret;
  }
  
  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;
  
  	port = uart_port_ref(state);
  	if (!port)
  		return;
  
  	if (ch == '\n')
  		port->ops->poll_put_char(port, '\r');
  	port->ops->poll_put_char(port, ch);
  	uart_port_deref(port);
  }
  #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,
  	.set_ldisc	= uart_set_ldisc,
  	.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
  	.proc_show	= uart_proc_show,
  #endif
  	.tiocmget	= uart_tiocmget,
  	.tiocmset	= uart_tiocmset,
  	.set_serial	= uart_set_info_user,
  	.get_serial	= uart_get_info_user,
  	.get_icount	= uart_get_icount,
  #ifdef CONFIG_CONSOLE_POLL
  	.poll_init	= uart_poll_init,
  	.poll_get_char	= uart_poll_get_char,
  	.poll_put_char	= uart_poll_put_char,
  #endif
  };
  
  static const struct tty_port_operations uart_port_ops = {
  	.carrier_raised = uart_carrier_raised,
  	.dtr_rts	= uart_dtr_rts,
  	.activate	= uart_port_activate,
  	.shutdown	= uart_tty_port_shutdown,
  };
  
  /**
   *	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;
  	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 = kcalloc(drv->nr, sizeof(struct uart_state), GFP_KERNEL);
  	if (!drv->state)
  		goto out;
  
  	normal = alloc_tty_driver(drv->nr);
  	if (!normal)
  		goto out_kfree;
  
  	drv->tty_driver = normal;
  
  	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;
  		struct tty_port *port = &state->port;
  
  		tty_port_init(port);
  		port->ops = &uart_port_ops;
  	}
  
  	retval = tty_register_driver(normal);
  	if (retval >= 0)
  		return retval;
  
  	for (i = 0; i < drv->nr; i++)
  		tty_port_destroy(&drv->state[i].port);
  	put_tty_driver(normal);
  out_kfree:
  	kfree(drv->state);
  out:
  	return -ENOMEM;
  }
  
  /**
   *	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;
  	unsigned int i;
  
  	tty_unregister_driver(p);
  	put_tty_driver(p);
  	for (i = 0; i < drv->nr; i++)
  		tty_port_destroy(&drv->state[i].port);
  	kfree(drv->state);
  	drv->state = NULL;
  	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;
  }
  
  static ssize_t uart_get_attr_uartclk(struct device *dev,
  	struct device_attribute *attr, char *buf)
  {
  	struct serial_struct tmp;
  	struct tty_port *port = dev_get_drvdata(dev);
  
  	uart_get_info(port, &tmp);
  	return snprintf(buf, PAGE_SIZE, "%d\n", tmp.baud_base * 16);
  }
  
  static ssize_t uart_get_attr_type(struct device *dev,
  	struct device_attribute *attr, char *buf)
  {
  	struct serial_struct tmp;
  	struct tty_port *port = dev_get_drvdata(dev);
  
  	uart_get_info(port, &tmp);
  	return snprintf(buf, PAGE_SIZE, "%d\n", tmp.type);
  }
  static ssize_t uart_get_attr_line(struct device *dev,
  	struct device_attribute *attr, char *buf)
  {
  	struct serial_struct tmp;
  	struct tty_port *port = dev_get_drvdata(dev);
  
  	uart_get_info(port, &tmp);
  	return snprintf(buf, PAGE_SIZE, "%d\n", tmp.line);
  }
  
  static ssize_t uart_get_attr_port(struct device *dev,
  	struct device_attribute *attr, char *buf)
  {
  	struct serial_struct tmp;
  	struct tty_port *port = dev_get_drvdata(dev);
  	unsigned long ioaddr;
  
  	uart_get_info(port, &tmp);
  	ioaddr = tmp.port;
  	if (HIGH_BITS_OFFSET)
  		ioaddr |= (unsigned long)tmp.port_high << HIGH_BITS_OFFSET;
  	return snprintf(buf, PAGE_SIZE, "0x%lX\n", ioaddr);
  }
  
  static ssize_t uart_get_attr_irq(struct device *dev,
  	struct device_attribute *attr, char *buf)
  {
  	struct serial_struct tmp;
  	struct tty_port *port = dev_get_drvdata(dev);
  
  	uart_get_info(port, &tmp);
  	return snprintf(buf, PAGE_SIZE, "%d\n", tmp.irq);
  }
  
  static ssize_t uart_get_attr_flags(struct device *dev,
  	struct device_attribute *attr, char *buf)
  {
  	struct serial_struct tmp;
  	struct tty_port *port = dev_get_drvdata(dev);
  
  	uart_get_info(port, &tmp);
  	return snprintf(buf, PAGE_SIZE, "0x%X\n", tmp.flags);
  }
  
  static ssize_t uart_get_attr_xmit_fifo_size(struct device *dev,
  	struct device_attribute *attr, char *buf)
  {
  	struct serial_struct tmp;
  	struct tty_port *port = dev_get_drvdata(dev);
  
  	uart_get_info(port, &tmp);
  	return snprintf(buf, PAGE_SIZE, "%d\n", tmp.xmit_fifo_size);
  }
  
  
  static ssize_t uart_get_attr_close_delay(struct device *dev,
  	struct device_attribute *attr, char *buf)
  {
  	struct serial_struct tmp;
  	struct tty_port *port = dev_get_drvdata(dev);
  
  	uart_get_info(port, &tmp);
  	return snprintf(buf, PAGE_SIZE, "%d\n", tmp.close_delay);
  }
  
  
  static ssize_t uart_get_attr_closing_wait(struct device *dev,
  	struct device_attribute *attr, char *buf)
  {
  	struct serial_struct tmp;
  	struct tty_port *port = dev_get_drvdata(dev);
  
  	uart_get_info(port, &tmp);
  	return snprintf(buf, PAGE_SIZE, "%d\n", tmp.closing_wait);
  }
  
  static ssize_t uart_get_attr_custom_divisor(struct device *dev,
  	struct device_attribute *attr, char *buf)
  {
  	struct serial_struct tmp;
  	struct tty_port *port = dev_get_drvdata(dev);
  
  	uart_get_info(port, &tmp);
  	return snprintf(buf, PAGE_SIZE, "%d\n", tmp.custom_divisor);
  }
  
  static ssize_t uart_get_attr_io_type(struct device *dev,
  	struct device_attribute *attr, char *buf)
  {
  	struct serial_struct tmp;
  	struct tty_port *port = dev_get_drvdata(dev);
  
  	uart_get_info(port, &tmp);
  	return snprintf(buf, PAGE_SIZE, "%d\n", tmp.io_type);
  }
  
  static ssize_t uart_get_attr_iomem_base(struct device *dev,
  	struct device_attribute *attr, char *buf)
  {
  	struct serial_struct tmp;
  	struct tty_port *port = dev_get_drvdata(dev);
  
  	uart_get_info(port, &tmp);
  	return snprintf(buf, PAGE_SIZE, "0x%lX\n", (unsigned long)tmp.iomem_base);
  }
  
  static ssize_t uart_get_attr_iomem_reg_shift(struct device *dev,
  	struct device_attribute *attr, char *buf)
  {
  	struct serial_struct tmp;
  	struct tty_port *port = dev_get_drvdata(dev);
  
  	uart_get_info(port, &tmp);
  	return snprintf(buf, PAGE_SIZE, "%d\n", tmp.iomem_reg_shift);
  }
  
  static DEVICE_ATTR(type, S_IRUSR | S_IRGRP, uart_get_attr_type, NULL);
  static DEVICE_ATTR(line, S_IRUSR | S_IRGRP, uart_get_attr_line, NULL);
  static DEVICE_ATTR(port, S_IRUSR | S_IRGRP, uart_get_attr_port, NULL);
  static DEVICE_ATTR(irq, S_IRUSR | S_IRGRP, uart_get_attr_irq, NULL);
  static DEVICE_ATTR(flags, S_IRUSR | S_IRGRP, uart_get_attr_flags, NULL);
  static DEVICE_ATTR(xmit_fifo_size, S_IRUSR | S_IRGRP, uart_get_attr_xmit_fifo_size, NULL);
  static DEVICE_ATTR(uartclk, S_IRUSR | S_IRGRP, uart_get_attr_uartclk, NULL);
  static DEVICE_ATTR(close_delay, S_IRUSR | S_IRGRP, uart_get_attr_close_delay, NULL);
  static DEVICE_ATTR(closing_wait, S_IRUSR | S_IRGRP, uart_get_attr_closing_wait, NULL);
  static DEVICE_ATTR(custom_divisor, S_IRUSR | S_IRGRP, uart_get_attr_custom_divisor, NULL);
  static DEVICE_ATTR(io_type, S_IRUSR | S_IRGRP, uart_get_attr_io_type, NULL);
  static DEVICE_ATTR(iomem_base, S_IRUSR | S_IRGRP, uart_get_attr_iomem_base, NULL);
  static DEVICE_ATTR(iomem_reg_shift, S_IRUSR | S_IRGRP, uart_get_attr_iomem_reg_shift, NULL);
  
  static struct attribute *tty_dev_attrs[] = {
  	&dev_attr_type.attr,
  	&dev_attr_line.attr,
  	&dev_attr_port.attr,
  	&dev_attr_irq.attr,
  	&dev_attr_flags.attr,
  	&dev_attr_xmit_fifo_size.attr,
  	&dev_attr_uartclk.attr,
  	&dev_attr_close_delay.attr,
  	&dev_attr_closing_wait.attr,
  	&dev_attr_custom_divisor.attr,
  	&dev_attr_io_type.attr,
  	&dev_attr_iomem_base.attr,
  	&dev_attr_iomem_reg_shift.attr,
  	NULL,
  	};
  
  static const struct attribute_group tty_dev_attr_group = {
  	.attrs = tty_dev_attrs,
  	};
  
  /**
   *	uart_add_one_port - attach a driver-defined port structure
   *	@drv: pointer to the uart low level driver structure for this port
   *	@uport: 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 *uport)
  {
  	struct uart_state *state;
  	struct tty_port *port;
  	int ret = 0;
  	struct device *tty_dev;
  	int num_groups;
  
  	BUG_ON(in_interrupt());
  
  	if (uport->line >= drv->nr)
  		return -EINVAL;
  
  	state = drv->state + uport->line;
  	port = &state->port;
  
  	mutex_lock(&port_mutex);
  	mutex_lock(&port->mutex);
  	if (state->uart_port) {
  		ret = -EINVAL;
  		goto out;
  	}
  
  	/* Link the port to the driver state table and vice versa */
  	atomic_set(&state->refcount, 1);
  	init_waitqueue_head(&state->remove_wait);
  	state->uart_port = uport;
  	uport->state = state;
  
  	state->pm_state = UART_PM_STATE_UNDEFINED;
  	uport->cons = drv->cons;
  	uport->minor = drv->tty_driver->minor_start + uport->line;
  	uport->name = kasprintf(GFP_KERNEL, "%s%d", drv->dev_name,
  				drv->tty_driver->name_base + uport->line);
  	if (!uport->name) {
  		ret = -ENOMEM;
  		goto out;
  	}
  
  	/*
  	 * If this port is a console, then the spinlock is already
  	 * initialised.
  	 */
  	if (!(uart_console(uport) && (uport->cons->flags & CON_ENABLED))) {
  		spin_lock_init(&uport->lock);
  		lockdep_set_class(&uport->lock, &port_lock_key);
  	}
  	if (uport->cons && uport->dev)
  		of_console_check(uport->dev->of_node, uport->cons->name, uport->line);
  
  	uart_configure_port(drv, state, uport);
  
  	port->console = uart_console(uport);
  
  	num_groups = 2;
  	if (uport->attr_group)
  		num_groups++;
  
  	uport->tty_groups = kcalloc(num_groups, sizeof(*uport->tty_groups),
  				    GFP_KERNEL);
  	if (!uport->tty_groups) {
  		ret = -ENOMEM;
  		goto out;
  	}
  	uport->tty_groups[0] = &tty_dev_attr_group;
  	if (uport->attr_group)
  		uport->tty_groups[1] = uport->attr_group;
  
  	/*
  	 * Register the port whether it's detected or not.  This allows
  	 * setserial to be used to alter this port's parameters.
  	 */
  	tty_dev = tty_port_register_device_attr_serdev(port, drv->tty_driver,
  			uport->line, uport->dev, port, uport->tty_groups);
  	if (!IS_ERR(tty_dev)) {
  		device_set_wakeup_capable(tty_dev, 1);
  	} else {
  		dev_err(uport->dev, "Cannot register tty device on line %d\n",
  		       uport->line);
  	}
  
  	/*
  	 * Ensure UPF_DEAD is not set.
  	 */
  	uport->flags &= ~UPF_DEAD;
  
   out:
  	mutex_unlock(&port->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
   *	@uport: 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 *uport)
  {
  	struct uart_state *state = drv->state + uport->line;
  	struct tty_port *port = &state->port;
  	struct uart_port *uart_port;
  	struct tty_struct *tty;
  	int ret = 0;
  
  	BUG_ON(in_interrupt());
  
  	mutex_lock(&port_mutex);
  
  	/*
  	 * Mark the port "dead" - this prevents any opens from
  	 * succeeding while we shut down the port.
  	 */
  	mutex_lock(&port->mutex);
  	uart_port = uart_port_check(state);
  	if (uart_port != uport)
  		dev_alert(uport->dev, "Removing wrong port: %p != %p\n",
  			  uart_port, uport);
  
  	if (!uart_port) {
  		mutex_unlock(&port->mutex);
  		ret = -EINVAL;
  		goto out;
  	}
  	uport->flags |= UPF_DEAD;
  	mutex_unlock(&port->mutex);
  
  	/*
  	 * Remove the devices from the tty layer
  	 */
  	tty_port_unregister_device(port, drv->tty_driver, uport->line);
  
  	tty = tty_port_tty_get(port);
  	if (tty) {
  		tty_vhangup(port->tty);
  		tty_kref_put(tty);
  	}
  
  	/*
  	 * If the port is used as a console, unregister it
  	 */
  	if (uart_console(uport))
  		unregister_console(uport->cons);
  
  	/*
  	 * Free the port IO and memory resources, if any.
  	 */
  	if (uport->type != PORT_UNKNOWN && uport->ops->release_port)
  		uport->ops->release_port(uport);
  	kfree(uport->tty_groups);
  	kfree(uport->name);
  
  	/*
  	 * Indicate that there isn't a port here anymore.
  	 */
  	uport->type = PORT_UNKNOWN;
  
  	mutex_lock(&port->mutex);
  	WARN_ON(atomic_dec_return(&state->refcount) < 0);
  	wait_event(state->remove_wait, !atomic_read(&state->refcount));
  	state->uart_port = NULL;
  	mutex_unlock(&port->mutex);
  out:
  	mutex_unlock(&port_mutex);
  
  	return ret;
  }
  
  /*
   *	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_MEM16:
  	case UPIO_MEM32:
  	case UPIO_MEM32BE:
  	case UPIO_AU:
  	case UPIO_TSI:
  		return (port1->mapbase == port2->mapbase);
  	}
  	return 0;
  }
  EXPORT_SYMBOL(uart_match_port);
  
  /**
   *	uart_handle_dcd_change - handle a change of carrier detect state
   *	@uport: uart_port structure for the open port
   *	@status: new carrier detect status, nonzero if active
   *
   *	Caller must hold uport->lock
   */
  void uart_handle_dcd_change(struct uart_port *uport, unsigned int status)
  {
  	struct tty_port *port = &uport->state->port;
  	struct tty_struct *tty = port->tty;
  	struct tty_ldisc *ld;
  
  	lockdep_assert_held_once(&uport->lock);
  
  	if (tty) {
  		ld = tty_ldisc_ref(tty);
  		if (ld) {
  			if (ld->ops->dcd_change)
  				ld->ops->dcd_change(tty, status);
  			tty_ldisc_deref(ld);
  		}
  	}
  
  	uport->icount.dcd++;
  
  	if (uart_dcd_enabled(uport)) {
  		if (status)
  			wake_up_interruptible(&port->open_wait);
  		else if (tty)
  			tty_hangup(tty);
  	}
  }
  EXPORT_SYMBOL_GPL(uart_handle_dcd_change);
  
  /**
   *	uart_handle_cts_change - handle a change of clear-to-send state
   *	@uport: uart_port structure for the open port
   *	@status: new clear to send status, nonzero if active
   *
   *	Caller must hold uport->lock
   */
  void uart_handle_cts_change(struct uart_port *uport, unsigned int status)
  {
  	lockdep_assert_held_once(&uport->lock);
  
  	uport->icount.cts++;
  
  	if (uart_softcts_mode(uport)) {
  		if (uport->hw_stopped) {
  			if (status) {
  				uport->hw_stopped = 0;
  				uport->ops->start_tx(uport);
  				uart_write_wakeup(uport);
  			}
  		} else {
  			if (!status) {
  				uport->hw_stopped = 1;
  				uport->ops->stop_tx(uport);
  			}
  		}
  
  	}
  }
  EXPORT_SYMBOL_GPL(uart_handle_cts_change);
  
  /**
   * uart_insert_char - push a char to the uart layer
   *
   * User is responsible to call tty_flip_buffer_push when they are done with
   * insertion.
   *
   * @port: corresponding port
   * @status: state of the serial port RX buffer (LSR for 8250)
   * @overrun: mask of overrun bits in @status
   * @ch: character to push
   * @flag: flag for the character (see TTY_NORMAL and friends)
   */
  void uart_insert_char(struct uart_port *port, unsigned int status,
  		 unsigned int overrun, unsigned int ch, unsigned int flag)
  {
  	struct tty_port *tport = &port->state->port;
  
  	if ((status & port->ignore_status_mask & ~overrun) == 0)
  		if (tty_insert_flip_char(tport, ch, flag) == 0)
  			++port->icount.buf_overrun;
  
  	/*
  	 * Overrun is special.  Since it's reported immediately,
  	 * it doesn't affect the current character.
  	 */
  	if (status & ~port->ignore_status_mask & overrun)
  		if (tty_insert_flip_char(tport, 0, TTY_OVERRUN) == 0)
  			++port->icount.buf_overrun;
  }
  EXPORT_SYMBOL_GPL(uart_insert_char);
  
  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);
  
  /**
   * uart_get_rs485_mode() - retrieve rs485 properties for given uart
   * @dev: uart device
   * @rs485conf: output parameter
   *
   * This function implements the device tree binding described in
   * Documentation/devicetree/bindings/serial/rs485.txt.
   */
  void uart_get_rs485_mode(struct device *dev, struct serial_rs485 *rs485conf)
  {
  	u32 rs485_delay[2];
  	int ret;
  
  	ret = device_property_read_u32_array(dev, "rs485-rts-delay",
  					     rs485_delay, 2);
  	if (!ret) {
  		rs485conf->delay_rts_before_send = rs485_delay[0];
  		rs485conf->delay_rts_after_send = rs485_delay[1];
  	} else {
  		rs485conf->delay_rts_before_send = 0;
  		rs485conf->delay_rts_after_send = 0;
  	}
  
  	/*
  	 * Clear full-duplex and enabled flags, set RTS polarity to active high
  	 * to get to a defined state with the following properties:
  	 */
  	rs485conf->flags &= ~(SER_RS485_RX_DURING_TX | SER_RS485_ENABLED |
  			      SER_RS485_RTS_AFTER_SEND);
  	rs485conf->flags |= SER_RS485_RTS_ON_SEND;
  
  	if (device_property_read_bool(dev, "rs485-rx-during-tx"))
  		rs485conf->flags |= SER_RS485_RX_DURING_TX;
  
  	if (device_property_read_bool(dev, "linux,rs485-enabled-at-boot-time"))
  		rs485conf->flags |= SER_RS485_ENABLED;
  
  	if (device_property_read_bool(dev, "rs485-rts-active-low")) {
  		rs485conf->flags &= ~SER_RS485_RTS_ON_SEND;
  		rs485conf->flags |= SER_RS485_RTS_AFTER_SEND;
  	}
  }
  EXPORT_SYMBOL_GPL(uart_get_rs485_mode);
  
  MODULE_DESCRIPTION("Serial driver core");
  MODULE_LICENSE("GPL");
  