/*
  *  Digi AccelePort USB-4 and USB-2 Serial Converters
  *
  *  Copyright 2000 by Digi International
  *
  *  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.
  *
  *  Shamelessly based on Brian Warner's keyspan_pda.c and Greg Kroah-Hartman's
  *  usb-serial driver.
  *
  *  Peter Berger (pberger@brimson.com)
  *  Al Borchers (borchers@steinerpoint.com)

  */

  #include <linux/kernel.h>
  #include <linux/errno.h>

  #include <linux/slab.h>
  #include <linux/tty.h>
  #include <linux/tty_driver.h>
  #include <linux/tty_flip.h>
  #include <linux/module.h>
  #include <linux/spinlock.h>
  #include <linux/workqueue.h>

  #include <linux/uaccess.h>

  #include <linux/usb.h>
  #include <linux/wait.h>

  #include <linux/sched/signal.h>

  #include <linux/usb/serial.h>

  
  /* Defines */

  #define DRIVER_AUTHOR "Peter Berger <pberger@brimson.com>, Al Borchers <borchers@steinerpoint.com>"
  #define DRIVER_DESC "Digi AccelePort USB-2/USB-4 Serial Converter driver"
  
  /* port output buffer length -- must be <= transfer buffer length - 2 */
  /* so we can be sure to send the full buffer in one urb */
  #define DIGI_OUT_BUF_SIZE		8
  
  /* port input buffer length -- must be >= transfer buffer length - 3 */
  /* so we can be sure to hold at least one full buffer from one urb */
  #define DIGI_IN_BUF_SIZE		64
  
  /* retry timeout while sleeping */
  #define DIGI_RETRY_TIMEOUT		(HZ/10)
  
  /* timeout while waiting for tty output to drain in close */
  /* this delay is used twice in close, so the total delay could */
  /* be twice this value */
  #define DIGI_CLOSE_TIMEOUT		(5*HZ)
  
  
  /* AccelePort USB Defines */
  
  /* ids */
  #define DIGI_VENDOR_ID			0x05c5
  #define DIGI_2_ID			0x0002	/* USB-2 */
  #define DIGI_4_ID			0x0004	/* USB-4 */
  
  /* commands
   * "INB": can be used on the in-band endpoint
   * "OOB": can be used on the out-of-band endpoint
   */
  #define DIGI_CMD_SET_BAUD_RATE			0	/* INB, OOB */
  #define DIGI_CMD_SET_WORD_SIZE			1	/* INB, OOB */
  #define DIGI_CMD_SET_PARITY			2	/* INB, OOB */
  #define DIGI_CMD_SET_STOP_BITS			3	/* INB, OOB */
  #define DIGI_CMD_SET_INPUT_FLOW_CONTROL		4	/* INB, OOB */
  #define DIGI_CMD_SET_OUTPUT_FLOW_CONTROL	5	/* INB, OOB */
  #define DIGI_CMD_SET_DTR_SIGNAL			6	/* INB, OOB */
  #define DIGI_CMD_SET_RTS_SIGNAL			7	/* INB, OOB */
  #define DIGI_CMD_READ_INPUT_SIGNALS		8	/*      OOB */
  #define DIGI_CMD_IFLUSH_FIFO			9	/*      OOB */
  #define DIGI_CMD_RECEIVE_ENABLE			10	/* INB, OOB */
  #define DIGI_CMD_BREAK_CONTROL			11	/* INB, OOB */
  #define DIGI_CMD_LOCAL_LOOPBACK			12	/* INB, OOB */
  #define DIGI_CMD_TRANSMIT_IDLE			13	/* INB, OOB */
  #define DIGI_CMD_READ_UART_REGISTER		14	/*      OOB */
  #define DIGI_CMD_WRITE_UART_REGISTER		15	/* INB, OOB */
  #define DIGI_CMD_AND_UART_REGISTER		16	/* INB, OOB */
  #define DIGI_CMD_OR_UART_REGISTER		17	/* INB, OOB */
  #define DIGI_CMD_SEND_DATA			18	/* INB      */
  #define DIGI_CMD_RECEIVE_DATA			19	/* INB      */
  #define DIGI_CMD_RECEIVE_DISABLE		20	/* INB      */
  #define DIGI_CMD_GET_PORT_TYPE			21	/*      OOB */
  
  /* baud rates */
  #define DIGI_BAUD_50				0
  #define DIGI_BAUD_75				1
  #define DIGI_BAUD_110				2
  #define DIGI_BAUD_150				3
  #define DIGI_BAUD_200				4
  #define DIGI_BAUD_300				5
  #define DIGI_BAUD_600				6
  #define DIGI_BAUD_1200				7
  #define DIGI_BAUD_1800				8
  #define DIGI_BAUD_2400				9
  #define DIGI_BAUD_4800				10
  #define DIGI_BAUD_7200				11
  #define DIGI_BAUD_9600				12
  #define DIGI_BAUD_14400				13
  #define DIGI_BAUD_19200				14
  #define DIGI_BAUD_28800				15
  #define DIGI_BAUD_38400				16
  #define DIGI_BAUD_57600				17
  #define DIGI_BAUD_76800				18
  #define DIGI_BAUD_115200			19
  #define DIGI_BAUD_153600			20
  #define DIGI_BAUD_230400			21
  #define DIGI_BAUD_460800			22
  
  /* arguments */
  #define DIGI_WORD_SIZE_5			0
  #define DIGI_WORD_SIZE_6			1
  #define DIGI_WORD_SIZE_7			2
  #define DIGI_WORD_SIZE_8			3
  
  #define DIGI_PARITY_NONE			0
  #define DIGI_PARITY_ODD				1
  #define DIGI_PARITY_EVEN			2
  #define DIGI_PARITY_MARK			3
  #define DIGI_PARITY_SPACE			4
  
  #define DIGI_STOP_BITS_1			0
  #define DIGI_STOP_BITS_2			1
  
  #define DIGI_INPUT_FLOW_CONTROL_XON_XOFF	1
  #define DIGI_INPUT_FLOW_CONTROL_RTS		2
  #define DIGI_INPUT_FLOW_CONTROL_DTR		4
  
  #define DIGI_OUTPUT_FLOW_CONTROL_XON_XOFF	1
  #define DIGI_OUTPUT_FLOW_CONTROL_CTS		2
  #define DIGI_OUTPUT_FLOW_CONTROL_DSR		4
  
  #define DIGI_DTR_INACTIVE			0
  #define DIGI_DTR_ACTIVE				1
  #define DIGI_DTR_INPUT_FLOW_CONTROL		2
  
  #define DIGI_RTS_INACTIVE			0
  #define DIGI_RTS_ACTIVE				1
  #define DIGI_RTS_INPUT_FLOW_CONTROL		2
  #define DIGI_RTS_TOGGLE				3
  
  #define DIGI_FLUSH_TX				1
  #define DIGI_FLUSH_RX				2
  #define DIGI_RESUME_TX				4 /* clears xoff condition */
  
  #define DIGI_TRANSMIT_NOT_IDLE			0
  #define DIGI_TRANSMIT_IDLE			1
  
  #define DIGI_DISABLE				0
  #define DIGI_ENABLE				1
  
  #define DIGI_DEASSERT				0
  #define DIGI_ASSERT				1
  
  /* in band status codes */
  #define DIGI_OVERRUN_ERROR			4
  #define DIGI_PARITY_ERROR			8
  #define DIGI_FRAMING_ERROR			16
  #define DIGI_BREAK_ERROR			32
  
  /* out of band status */
  #define DIGI_NO_ERROR				0
  #define DIGI_BAD_FIRST_PARAMETER		1
  #define DIGI_BAD_SECOND_PARAMETER		2
  #define DIGI_INVALID_LINE			3
  #define DIGI_INVALID_OPCODE			4
  
  /* input signals */
  #define DIGI_READ_INPUT_SIGNALS_SLOT		1
  #define DIGI_READ_INPUT_SIGNALS_ERR		2
  #define DIGI_READ_INPUT_SIGNALS_BUSY		4
  #define DIGI_READ_INPUT_SIGNALS_PE		8
  #define DIGI_READ_INPUT_SIGNALS_CTS		16
  #define DIGI_READ_INPUT_SIGNALS_DSR		32
  #define DIGI_READ_INPUT_SIGNALS_RI		64
  #define DIGI_READ_INPUT_SIGNALS_DCD		128
  
  
  /* Structures */
  
  struct digi_serial {
  	spinlock_t ds_serial_lock;
  	struct usb_serial_port *ds_oob_port;	/* out-of-band port */
  	int ds_oob_port_num;			/* index of out-of-band port */
  	int ds_device_started;
  };
  
  struct digi_port {
  	spinlock_t dp_port_lock;
  	int dp_port_num;
  	int dp_out_buf_len;
  	unsigned char dp_out_buf[DIGI_OUT_BUF_SIZE];

  	int dp_write_urb_in_use;
  	unsigned int dp_modem_signals;

  	int dp_transmit_idle;
  	wait_queue_head_t dp_transmit_idle_wait;
  	int dp_throttled;
  	int dp_throttle_restart;
  	wait_queue_head_t dp_flush_wait;

  	wait_queue_head_t dp_close_wait;	/* wait queue for close */
  	struct work_struct dp_wakeup_work;

  	struct usb_serial_port *dp_port;

  };
  
  
  /* Local Function Declarations */

  static void digi_wakeup_write_lock(struct work_struct *work);

  static int digi_write_oob_command(struct usb_serial_port *port,
  	unsigned char *buf, int count, int interruptible);
  static int digi_write_inb_command(struct usb_serial_port *port,
  	unsigned char *buf, int count, unsigned long timeout);
  static int digi_set_modem_signals(struct usb_serial_port *port,
  	unsigned int modem_signals, int interruptible);
  static int digi_transmit_idle(struct usb_serial_port *port,
  	unsigned long timeout);

  static void digi_rx_throttle(struct tty_struct *tty);
  static void digi_rx_unthrottle(struct tty_struct *tty);

  static void digi_set_termios(struct tty_struct *tty,
  		struct usb_serial_port *port, struct ktermios *old_termios);
  static void digi_break_ctl(struct tty_struct *tty, int break_state);

  static int digi_tiocmget(struct tty_struct *tty);

  static int digi_tiocmset(struct tty_struct *tty, unsigned int set,
  		unsigned int clear);

  static int digi_write(struct tty_struct *tty, struct usb_serial_port *port,

  		const unsigned char *buf, int count);

  static void digi_write_bulk_callback(struct urb *urb);

  static int digi_write_room(struct tty_struct *tty);
  static int digi_chars_in_buffer(struct tty_struct *tty);

  static int digi_open(struct tty_struct *tty, struct usb_serial_port *port);

  static void digi_close(struct usb_serial_port *port);

  static void digi_dtr_rts(struct usb_serial_port *port, int on);

  static int digi_startup_device(struct usb_serial *serial);
  static int digi_startup(struct usb_serial *serial);

  static void digi_disconnect(struct usb_serial *serial);
  static void digi_release(struct usb_serial *serial);

  static int digi_port_probe(struct usb_serial_port *port);
  static int digi_port_remove(struct usb_serial_port *port);

  static void digi_read_bulk_callback(struct urb *urb);
  static int digi_read_inb_callback(struct urb *urb);
  static int digi_read_oob_callback(struct urb *urb);

  static const struct usb_device_id id_table_combined[] = {

  	{ USB_DEVICE(DIGI_VENDOR_ID, DIGI_2_ID) },
  	{ USB_DEVICE(DIGI_VENDOR_ID, DIGI_4_ID) },
  	{ }						/* Terminating entry */
  };

  static const struct usb_device_id id_table_2[] = {

  	{ USB_DEVICE(DIGI_VENDOR_ID, DIGI_2_ID) },
  	{ }						/* Terminating entry */
  };

  static const struct usb_device_id id_table_4[] = {

  	{ USB_DEVICE(DIGI_VENDOR_ID, DIGI_4_ID) },
  	{ }						/* Terminating entry */
  };

  MODULE_DEVICE_TABLE(usb, id_table_combined);

  /* device info needed for the Digi serial converter */

  static struct usb_serial_driver digi_acceleport_2_device = {

  	.driver = {

  		.owner =		THIS_MODULE,
  		.name =			"digi_2",

  	},

  	.description =			"Digi 2 port USB adapter",

  	.id_table =			id_table_2,

  	.num_ports =			3,

  	.num_bulk_in =			4,
  	.num_bulk_out =			4,

  	.open =				digi_open,
  	.close =			digi_close,

  	.dtr_rts =			digi_dtr_rts,

  	.write =			digi_write,
  	.write_room =			digi_write_room,
  	.write_bulk_callback = 		digi_write_bulk_callback,
  	.read_bulk_callback =		digi_read_bulk_callback,
  	.chars_in_buffer =		digi_chars_in_buffer,
  	.throttle =			digi_rx_throttle,
  	.unthrottle =			digi_rx_unthrottle,

  	.set_termios =			digi_set_termios,
  	.break_ctl =			digi_break_ctl,
  	.tiocmget =			digi_tiocmget,
  	.tiocmset =			digi_tiocmset,
  	.attach =			digi_startup,

  	.disconnect =			digi_disconnect,
  	.release =			digi_release,

  	.port_probe =			digi_port_probe,
  	.port_remove =			digi_port_remove,

  };

  static struct usb_serial_driver digi_acceleport_4_device = {

  	.driver = {

  		.owner =		THIS_MODULE,
  		.name =			"digi_4",

  	},

  	.description =			"Digi 4 port USB adapter",

  	.id_table =			id_table_4,

  	.num_ports =			4,

  	.num_bulk_in =			5,
  	.num_bulk_out =			5,

  	.open =				digi_open,
  	.close =			digi_close,
  	.write =			digi_write,
  	.write_room =			digi_write_room,
  	.write_bulk_callback = 		digi_write_bulk_callback,
  	.read_bulk_callback =		digi_read_bulk_callback,
  	.chars_in_buffer =		digi_chars_in_buffer,
  	.throttle =			digi_rx_throttle,
  	.unthrottle =			digi_rx_unthrottle,

  	.set_termios =			digi_set_termios,
  	.break_ctl =			digi_break_ctl,
  	.tiocmget =			digi_tiocmget,
  	.tiocmset =			digi_tiocmset,
  	.attach =			digi_startup,

  	.disconnect =			digi_disconnect,
  	.release =			digi_release,

  	.port_probe =			digi_port_probe,
  	.port_remove =			digi_port_remove,

  };

  static struct usb_serial_driver * const serial_drivers[] = {
  	&digi_acceleport_2_device, &digi_acceleport_4_device, NULL
  };

  
  /* Functions */
  
  /*

   *  Cond Wait Interruptible Timeout Irqrestore
   *
   *  Do spin_unlock_irqrestore and interruptible_sleep_on_timeout
   *  so that wake ups are not lost if they occur between the unlock
   *  and the sleep.  In other words, spin_unlock_irqrestore and
   *  interruptible_sleep_on_timeout are "atomic" with respect to
   *  wake ups.  This is used to implement condition variables.
   *
   *  interruptible_sleep_on_timeout is deprecated and has been replaced
   *  with the equivalent code.
   */

  static long cond_wait_interruptible_timeout_irqrestore(

  	wait_queue_head_t *q, long timeout,

  	spinlock_t *lock, unsigned long flags)

  __releases(lock)

  {
  	DEFINE_WAIT(wait);

  	prepare_to_wait(q, &wait, TASK_INTERRUPTIBLE);

  	spin_unlock_irqrestore(lock, flags);
  	timeout = schedule_timeout(timeout);
  	finish_wait(q, &wait);
  
  	return timeout;

  }
  
  
  /*

   *  Digi Wakeup Write
   *
   *  Wake up port, line discipline, and tty processes sleeping
   *  on writes.
   */

  static void digi_wakeup_write_lock(struct work_struct *work)

  {

  	struct digi_port *priv =
  			container_of(work, struct digi_port, dp_wakeup_work);

  	struct usb_serial_port *port = priv->dp_port;

  	unsigned long flags;

  	spin_lock_irqsave(&priv->dp_port_lock, flags);

  	tty_port_tty_wakeup(&port->port);

  	spin_unlock_irqrestore(&priv->dp_port_lock, flags);

  }

  /*

   *  Digi Write OOB Command
   *
   *  Write commands on the out of band port.  Commands are 4
   *  bytes each, multiple commands can be sent at once, and
   *  no command will be split across USB packets.  Returns 0
   *  if successful, -EINTR if interrupted while sleeping and
   *  the interruptible flag is true, or a negative error
   *  returned by usb_submit_urb.
   */

  static int digi_write_oob_command(struct usb_serial_port *port,
  	unsigned char *buf, int count, int interruptible)

  {

  	int ret = 0;
  	int len;
  	struct usb_serial_port *oob_port = (struct usb_serial_port *)((struct digi_serial *)(usb_get_serial_data(port->serial)))->ds_oob_port;
  	struct digi_port *oob_priv = usb_get_serial_port_data(oob_port);
  	unsigned long flags = 0;

  	dev_dbg(&port->dev,
  		"digi_write_oob_command: TOP: port=%d, count=%d
  ",
  		oob_priv->dp_port_num, count);

  	spin_lock_irqsave(&oob_priv->dp_port_lock, flags);

  	while (count > 0) {

  		while (oob_priv->dp_write_urb_in_use) {

  			cond_wait_interruptible_timeout_irqrestore(
  				&oob_port->write_wait, DIGI_RETRY_TIMEOUT,

  				&oob_priv->dp_port_lock, flags);
  			if (interruptible && signal_pending(current))
  				return -EINTR;
  			spin_lock_irqsave(&oob_priv->dp_port_lock, flags);

  		}
  
  		/* len must be a multiple of 4, so commands are not split */

  		len = min(count, oob_port->bulk_out_size);
  		if (len > 4)

  			len &= ~3;

  		memcpy(oob_port->write_urb->transfer_buffer, buf, len);

  		oob_port->write_urb->transfer_buffer_length = len;

  		ret = usb_submit_urb(oob_port->write_urb, GFP_ATOMIC);
  		if (ret == 0) {

  			oob_priv->dp_write_urb_in_use = 1;
  			count -= len;
  			buf += len;
  		}

  	}

  	spin_unlock_irqrestore(&oob_priv->dp_port_lock, flags);
  	if (ret)

  		dev_err(&port->dev, "%s: usb_submit_urb failed, ret=%d
  ",
  			__func__, ret);

  	return ret;

  
  }
  
  
  /*

   *  Digi Write In Band Command
   *
   *  Write commands on the given port.  Commands are 4
   *  bytes each, multiple commands can be sent at once, and
   *  no command will be split across USB packets.  If timeout
   *  is non-zero, write in band command will return after
   *  waiting unsuccessfully for the URB status to clear for
   *  timeout ticks.  Returns 0 if successful, or a negative
   *  error returned by digi_write.
   */

  static int digi_write_inb_command(struct usb_serial_port *port,
  	unsigned char *buf, int count, unsigned long timeout)

  {

  	int ret = 0;
  	int len;
  	struct digi_port *priv = usb_get_serial_port_data(port);
  	unsigned char *data = port->write_urb->transfer_buffer;
  	unsigned long flags = 0;

  	dev_dbg(&port->dev, "digi_write_inb_command: TOP: port=%d, count=%d
  ",

  		priv->dp_port_num, count);

  	if (timeout)

  		timeout += jiffies;
  	else
  		timeout = ULONG_MAX;

  	spin_lock_irqsave(&priv->dp_port_lock, flags);

  	while (count > 0 && ret == 0) {

  		while (priv->dp_write_urb_in_use &&
  		       time_before(jiffies, timeout)) {

  			cond_wait_interruptible_timeout_irqrestore(
  				&port->write_wait, DIGI_RETRY_TIMEOUT,

  				&priv->dp_port_lock, flags);
  			if (signal_pending(current))
  				return -EINTR;
  			spin_lock_irqsave(&priv->dp_port_lock, flags);

  		}
  
  		/* len must be a multiple of 4 and small enough to */
  		/* guarantee the write will send buffered data first, */
  		/* so commands are in order with data and not split */

  		len = min(count, port->bulk_out_size-2-priv->dp_out_buf_len);
  		if (len > 4)

  			len &= ~3;
  
  		/* write any buffered data first */

  		if (priv->dp_out_buf_len > 0) {

  			data[0] = DIGI_CMD_SEND_DATA;
  			data[1] = priv->dp_out_buf_len;

  			memcpy(data + 2, priv->dp_out_buf,
  				priv->dp_out_buf_len);
  			memcpy(data + 2 + priv->dp_out_buf_len, buf, len);

  			port->write_urb->transfer_buffer_length

  				= priv->dp_out_buf_len + 2 + len;

  		} else {

  			memcpy(data, buf, len);

  			port->write_urb->transfer_buffer_length = len;
  		}

  		ret = usb_submit_urb(port->write_urb, GFP_ATOMIC);
  		if (ret == 0) {

  			priv->dp_write_urb_in_use = 1;
  			priv->dp_out_buf_len = 0;
  			count -= len;
  			buf += len;
  		}
  
  	}

  	spin_unlock_irqrestore(&priv->dp_port_lock, flags);

  	if (ret)

  		dev_err(&port->dev,
  			"%s: usb_submit_urb failed, ret=%d, port=%d
  ",

  			__func__, ret, priv->dp_port_num);

  	return ret;

  }
  
  
  /*

   *  Digi Set Modem Signals
   *
   *  Sets or clears DTR and RTS on the port, according to the
   *  modem_signals argument.  Use TIOCM_DTR and TIOCM_RTS flags
   *  for the modem_signals argument.  Returns 0 if successful,
   *  -EINTR if interrupted while sleeping, or a non-zero error
   *  returned by usb_submit_urb.
   */

  static int digi_set_modem_signals(struct usb_serial_port *port,
  	unsigned int modem_signals, int interruptible)

  {
  
  	int ret;
  	struct digi_port *port_priv = usb_get_serial_port_data(port);

  	struct usb_serial_port *oob_port = (struct usb_serial_port *) ((struct digi_serial *)(usb_get_serial_data(port->serial)))->ds_oob_port;

  	struct digi_port *oob_priv = usb_get_serial_port_data(oob_port);
  	unsigned char *data = oob_port->write_urb->transfer_buffer;
  	unsigned long flags = 0;

  	dev_dbg(&port->dev,
  		"digi_set_modem_signals: TOP: port=%d, modem_signals=0x%x
  ",

  		port_priv->dp_port_num, modem_signals);

  	spin_lock_irqsave(&oob_priv->dp_port_lock, flags);
  	spin_lock(&port_priv->dp_port_lock);

  	while (oob_priv->dp_write_urb_in_use) {

  		spin_unlock(&port_priv->dp_port_lock);

  		cond_wait_interruptible_timeout_irqrestore(
  			&oob_port->write_wait, DIGI_RETRY_TIMEOUT,

  			&oob_priv->dp_port_lock, flags);
  		if (interruptible && signal_pending(current))
  			return -EINTR;
  		spin_lock_irqsave(&oob_priv->dp_port_lock, flags);
  		spin_lock(&port_priv->dp_port_lock);

  	}

  	data[0] = DIGI_CMD_SET_DTR_SIGNAL;
  	data[1] = port_priv->dp_port_num;

  	data[2] = (modem_signals & TIOCM_DTR) ?
  					DIGI_DTR_ACTIVE : DIGI_DTR_INACTIVE;

  	data[3] = 0;

  	data[4] = DIGI_CMD_SET_RTS_SIGNAL;
  	data[5] = port_priv->dp_port_num;

  	data[6] = (modem_signals & TIOCM_RTS) ?
  					DIGI_RTS_ACTIVE : DIGI_RTS_INACTIVE;

  	data[7] = 0;
  
  	oob_port->write_urb->transfer_buffer_length = 8;

  	ret = usb_submit_urb(oob_port->write_urb, GFP_ATOMIC);
  	if (ret == 0) {

  		oob_priv->dp_write_urb_in_use = 1;
  		port_priv->dp_modem_signals =
  			(port_priv->dp_modem_signals&~(TIOCM_DTR|TIOCM_RTS))
  			| (modem_signals&(TIOCM_DTR|TIOCM_RTS));
  	}

  	spin_unlock(&port_priv->dp_port_lock);
  	spin_unlock_irqrestore(&oob_priv->dp_port_lock, flags);
  	if (ret)

  		dev_err(&port->dev, "%s: usb_submit_urb failed, ret=%d
  ",
  			__func__, ret);

  	return ret;

  }

  /*

   *  Digi Transmit Idle
   *
   *  Digi transmit idle waits, up to timeout ticks, for the transmitter
   *  to go idle.  It returns 0 if successful or a negative error.
   *
   *  There are race conditions here if more than one process is calling
   *  digi_transmit_idle on the same port at the same time.  However, this
   *  is only called from close, and only one process can be in close on a
   *  port at a time, so its ok.
   */

  static int digi_transmit_idle(struct usb_serial_port *port,
  	unsigned long timeout)

  {

  	int ret;
  	unsigned char buf[2];
  	struct digi_port *priv = usb_get_serial_port_data(port);
  	unsigned long flags = 0;

  	spin_lock_irqsave(&priv->dp_port_lock, flags);

  	priv->dp_transmit_idle = 0;

  	spin_unlock_irqrestore(&priv->dp_port_lock, flags);

  
  	buf[0] = DIGI_CMD_TRANSMIT_IDLE;
  	buf[1] = 0;
  
  	timeout += jiffies;

  	ret = digi_write_inb_command(port, buf, 2, timeout - jiffies);
  	if (ret != 0)

  		return ret;

  	spin_lock_irqsave(&priv->dp_port_lock, flags);

  	while (time_before(jiffies, timeout) && !priv->dp_transmit_idle) {

  		cond_wait_interruptible_timeout_irqrestore(
  			&priv->dp_transmit_idle_wait, DIGI_RETRY_TIMEOUT,

  			&priv->dp_port_lock, flags);
  		if (signal_pending(current))
  			return -EINTR;
  		spin_lock_irqsave(&priv->dp_port_lock, flags);

  	}

  	priv->dp_transmit_idle = 0;

  	spin_unlock_irqrestore(&priv->dp_port_lock, flags);
  	return 0;

  
  }

  static void digi_rx_throttle(struct tty_struct *tty)

  {

  	unsigned long flags;

  	struct usb_serial_port *port = tty->driver_data;

  	struct digi_port *priv = usb_get_serial_port_data(port);

  	/* stop receiving characters by not resubmitting the read urb */

  	spin_lock_irqsave(&priv->dp_port_lock, flags);

  	priv->dp_throttled = 1;
  	priv->dp_throttle_restart = 0;

  	spin_unlock_irqrestore(&priv->dp_port_lock, flags);

  }

  static void digi_rx_unthrottle(struct tty_struct *tty)

  {

  	int ret = 0;

  	unsigned long flags;

  	struct usb_serial_port *port = tty->driver_data;

  	struct digi_port *priv = usb_get_serial_port_data(port);

  	spin_lock_irqsave(&priv->dp_port_lock, flags);

  	/* restart read chain */

  	if (priv->dp_throttle_restart)

  		ret = usb_submit_urb(port->read_urb, GFP_ATOMIC);

  	/* turn throttle off */
  	priv->dp_throttled = 0;
  	priv->dp_throttle_restart = 0;

  	spin_unlock_irqrestore(&priv->dp_port_lock, flags);

  	if (ret)

  		dev_err(&port->dev,
  			"%s: usb_submit_urb failed, ret=%d, port=%d
  ",

  			__func__, ret, priv->dp_port_num);

  }

  static void digi_set_termios(struct tty_struct *tty,

  		struct usb_serial_port *port, struct ktermios *old_termios)

  {

  	struct digi_port *priv = usb_get_serial_port_data(port);

  	struct device *dev = &port->dev;

  	unsigned int iflag = tty->termios.c_iflag;
  	unsigned int cflag = tty->termios.c_cflag;

  	unsigned int old_iflag = old_termios->c_iflag;
  	unsigned int old_cflag = old_termios->c_cflag;
  	unsigned char buf[32];
  	unsigned int modem_signals;

  	int arg, ret;

  	int i = 0;

  	speed_t baud;

  	dev_dbg(dev,
  		"digi_set_termios: TOP: port=%d, iflag=0x%x, old_iflag=0x%x, cflag=0x%x, old_cflag=0x%x
  ",
  		priv->dp_port_num, iflag, old_iflag, cflag, old_cflag);

  
  	/* set baud rate */

  	baud = tty_get_baud_rate(tty);
  	if (baud != tty_termios_baud_rate(old_termios)) {

  		arg = -1;
  
  		/* reassert DTR and (maybe) RTS on transition from B0 */

  		if ((old_cflag & CBAUD) == B0) {

  			/* don't set RTS if using hardware flow control */
  			/* and throttling input */
  			modem_signals = TIOCM_DTR;

  			if (!C_CRTSCTS(tty) || !tty_throttled(tty))

  				modem_signals |= TIOCM_RTS;

  			digi_set_modem_signals(port, modem_signals, 1);

  		}

  		switch (baud) {

  		/* drop DTR and RTS on transition to B0 */
  		case 0: digi_set_modem_signals(port, 0, 1); break;
  		case 50: arg = DIGI_BAUD_50; break;
  		case 75: arg = DIGI_BAUD_75; break;
  		case 110: arg = DIGI_BAUD_110; break;
  		case 150: arg = DIGI_BAUD_150; break;
  		case 200: arg = DIGI_BAUD_200; break;
  		case 300: arg = DIGI_BAUD_300; break;
  		case 600: arg = DIGI_BAUD_600; break;
  		case 1200: arg = DIGI_BAUD_1200; break;
  		case 1800: arg = DIGI_BAUD_1800; break;
  		case 2400: arg = DIGI_BAUD_2400; break;
  		case 4800: arg = DIGI_BAUD_4800; break;
  		case 9600: arg = DIGI_BAUD_9600; break;
  		case 19200: arg = DIGI_BAUD_19200; break;
  		case 38400: arg = DIGI_BAUD_38400; break;
  		case 57600: arg = DIGI_BAUD_57600; break;
  		case 115200: arg = DIGI_BAUD_115200; break;
  		case 230400: arg = DIGI_BAUD_230400; break;
  		case 460800: arg = DIGI_BAUD_460800; break;
  		default:
  			arg = DIGI_BAUD_9600;
  			baud = 9600;
  			break;

  		}

  		if (arg != -1) {

  			buf[i++] = DIGI_CMD_SET_BAUD_RATE;
  			buf[i++] = priv->dp_port_num;
  			buf[i++] = arg;
  			buf[i++] = 0;
  		}

  	}

  	/* set parity */

  	tty->termios.c_cflag &= ~CMSPAR;

  	if ((cflag&(PARENB|PARODD)) != (old_cflag&(PARENB|PARODD))) {
  		if (cflag&PARENB) {
  			if (cflag&PARODD)

  				arg = DIGI_PARITY_ODD;
  			else
  				arg = DIGI_PARITY_EVEN;
  		} else {
  			arg = DIGI_PARITY_NONE;
  		}

  		buf[i++] = DIGI_CMD_SET_PARITY;
  		buf[i++] = priv->dp_port_num;
  		buf[i++] = arg;
  		buf[i++] = 0;

  	}

  	/* set word size */

  	if ((cflag&CSIZE) != (old_cflag&CSIZE)) {

  		arg = -1;

  		switch (cflag&CSIZE) {

  		case CS5: arg = DIGI_WORD_SIZE_5; break;
  		case CS6: arg = DIGI_WORD_SIZE_6; break;
  		case CS7: arg = DIGI_WORD_SIZE_7; break;
  		case CS8: arg = DIGI_WORD_SIZE_8; break;
  		default:

  			dev_dbg(dev,
  				"digi_set_termios: can't handle word size %d
  ",

  				(cflag&CSIZE));

  			break;
  		}

  		if (arg != -1) {

  			buf[i++] = DIGI_CMD_SET_WORD_SIZE;
  			buf[i++] = priv->dp_port_num;
  			buf[i++] = arg;
  			buf[i++] = 0;
  		}
  
  	}
  
  	/* set stop bits */

  	if ((cflag&CSTOPB) != (old_cflag&CSTOPB)) {

  		if ((cflag&CSTOPB))

  			arg = DIGI_STOP_BITS_2;
  		else
  			arg = DIGI_STOP_BITS_1;
  
  		buf[i++] = DIGI_CMD_SET_STOP_BITS;
  		buf[i++] = priv->dp_port_num;
  		buf[i++] = arg;
  		buf[i++] = 0;
  
  	}
  
  	/* set input flow control */

  	if ((iflag&IXOFF) != (old_iflag&IXOFF)
  	    || (cflag&CRTSCTS) != (old_cflag&CRTSCTS)) {

  		arg = 0;

  		if (iflag&IXOFF)

  			arg |= DIGI_INPUT_FLOW_CONTROL_XON_XOFF;
  		else
  			arg &= ~DIGI_INPUT_FLOW_CONTROL_XON_XOFF;

  		if (cflag&CRTSCTS) {

  			arg |= DIGI_INPUT_FLOW_CONTROL_RTS;
  
  			/* On USB-4 it is necessary to assert RTS prior */
  			/* to selecting RTS input flow control.  */
  			buf[i++] = DIGI_CMD_SET_RTS_SIGNAL;
  			buf[i++] = priv->dp_port_num;
  			buf[i++] = DIGI_RTS_ACTIVE;
  			buf[i++] = 0;
  
  		} else {
  			arg &= ~DIGI_INPUT_FLOW_CONTROL_RTS;
  		}

  		buf[i++] = DIGI_CMD_SET_INPUT_FLOW_CONTROL;
  		buf[i++] = priv->dp_port_num;
  		buf[i++] = arg;
  		buf[i++] = 0;

  	}
  
  	/* set output flow control */

  	if ((iflag & IXON) != (old_iflag & IXON)
  	    || (cflag & CRTSCTS) != (old_cflag & CRTSCTS)) {

  		arg = 0;

  		if (iflag & IXON)

  			arg |= DIGI_OUTPUT_FLOW_CONTROL_XON_XOFF;
  		else
  			arg &= ~DIGI_OUTPUT_FLOW_CONTROL_XON_XOFF;

  		if (cflag & CRTSCTS) {

  			arg |= DIGI_OUTPUT_FLOW_CONTROL_CTS;
  		} else {
  			arg &= ~DIGI_OUTPUT_FLOW_CONTROL_CTS;

  		}
  
  		buf[i++] = DIGI_CMD_SET_OUTPUT_FLOW_CONTROL;
  		buf[i++] = priv->dp_port_num;
  		buf[i++] = arg;
  		buf[i++] = 0;

  	}
  
  	/* set receive enable/disable */

  	if ((cflag & CREAD) != (old_cflag & CREAD)) {
  		if (cflag & CREAD)

  			arg = DIGI_ENABLE;
  		else
  			arg = DIGI_DISABLE;
  
  		buf[i++] = DIGI_CMD_RECEIVE_ENABLE;
  		buf[i++] = priv->dp_port_num;
  		buf[i++] = arg;
  		buf[i++] = 0;

  	}

  	ret = digi_write_oob_command(port, buf, i, 1);
  	if (ret != 0)

  		dev_dbg(dev, "digi_set_termios: write oob failed, ret=%d
  ", ret);

  	tty_encode_baud_rate(tty, baud, baud);

  }

  static void digi_break_ctl(struct tty_struct *tty, int break_state)

  {

  	struct usb_serial_port *port = tty->driver_data;

  	unsigned char buf[4];

  	buf[0] = DIGI_CMD_BREAK_CONTROL;
  	buf[1] = 2;				/* length */
  	buf[2] = break_state ? 1 : 0;
  	buf[3] = 0;				/* pad */

  	digi_write_inb_command(port, buf, 4, 0);

  }

  static int digi_tiocmget(struct tty_struct *tty)

  {

  	struct usb_serial_port *port = tty->driver_data;

  	struct digi_port *priv = usb_get_serial_port_data(port);
  	unsigned int val;
  	unsigned long flags;

  	spin_lock_irqsave(&priv->dp_port_lock, flags);

  	val = priv->dp_modem_signals;

  	spin_unlock_irqrestore(&priv->dp_port_lock, flags);

  	return val;
  }

  static int digi_tiocmset(struct tty_struct *tty,
  					unsigned int set, unsigned int clear)

  {

  	struct usb_serial_port *port = tty->driver_data;

  	struct digi_port *priv = usb_get_serial_port_data(port);
  	unsigned int val;
  	unsigned long flags;

  	spin_lock_irqsave(&priv->dp_port_lock, flags);

  	val = (priv->dp_modem_signals & ~clear) | set;

  	spin_unlock_irqrestore(&priv->dp_port_lock, flags);
  	return digi_set_modem_signals(port, val, 1);

  }

  static int digi_write(struct tty_struct *tty, struct usb_serial_port *port,
  					const unsigned char *buf, int count)

  {

  	int ret, data_len, new_len;

  	struct digi_port *priv = usb_get_serial_port_data(port);
  	unsigned char *data = port->write_urb->transfer_buffer;
  	unsigned long flags = 0;

  	dev_dbg(&port->dev,
  		"digi_write: TOP: port=%d, count=%d, in_interrupt=%ld
  ",

  		priv->dp_port_num, count, in_interrupt());

  
  	/* copy user data (which can sleep) before getting spin lock */

  	count = min(count, port->bulk_out_size-2);
  	count = min(64, count);

  
  	/* be sure only one write proceeds at a time */
  	/* there are races on the port private buffer */

  	spin_lock_irqsave(&priv->dp_port_lock, flags);

  
  	/* wait for urb status clear to submit another urb */

  	if (priv->dp_write_urb_in_use) {

  		/* buffer data if count is 1 (probably put_char) if possible */

  		if (count == 1 && priv->dp_out_buf_len < DIGI_OUT_BUF_SIZE) {

  			priv->dp_out_buf[priv->dp_out_buf_len++] = *buf;
  			new_len = 1;
  		} else {
  			new_len = 0;
  		}

  		spin_unlock_irqrestore(&priv->dp_port_lock, flags);
  		return new_len;

  	}
  
  	/* allow space for any buffered data and for new data, up to */
  	/* transfer buffer size - 2 (for command and length bytes) */
  	new_len = min(count, port->bulk_out_size-2-priv->dp_out_buf_len);
  	data_len = new_len + priv->dp_out_buf_len;

  	if (data_len == 0) {
  		spin_unlock_irqrestore(&priv->dp_port_lock, flags);
  		return 0;

  	}
  
  	port->write_urb->transfer_buffer_length = data_len+2;

  
  	*data++ = DIGI_CMD_SEND_DATA;
  	*data++ = data_len;
  
  	/* copy in buffered data first */

  	memcpy(data, priv->dp_out_buf, priv->dp_out_buf_len);

  	data += priv->dp_out_buf_len;
  
  	/* copy in new data */

  	memcpy(data, buf, new_len);

  	ret = usb_submit_urb(port->write_urb, GFP_ATOMIC);
  	if (ret == 0) {

  		priv->dp_write_urb_in_use = 1;
  		ret = new_len;
  		priv->dp_out_buf_len = 0;
  	}
  
  	/* return length of new data written, or error */

  	spin_unlock_irqrestore(&priv->dp_port_lock, flags);
  	if (ret < 0)

  		dev_err_console(port,

  			"%s: usb_submit_urb failed, ret=%d, port=%d
  ",

  			__func__, ret, priv->dp_port_num);

  	dev_dbg(&port->dev, "digi_write: returning %d
  ", ret);

  	return ret;

  }

  static void digi_write_bulk_callback(struct urb *urb)

  {

  	struct usb_serial_port *port = urb->context;

  	struct usb_serial *serial;
  	struct digi_port *priv;
  	struct digi_serial *serial_priv;
  	int ret = 0;

  	int status = urb->status;

  	/* port and serial sanity check */

  	if (port == NULL || (priv = usb_get_serial_port_data(port)) == NULL) {

  		pr_err("%s: port or port->private is NULL, status=%d
  ",

  			__func__, status);

  		return;
  	}
  	serial = port->serial;

  	if (serial == NULL || (serial_priv = usb_get_serial_data(serial)) == NULL) {

  		dev_err(&port->dev,
  			"%s: serial or serial->private is NULL, status=%d
  ",
  			__func__, status);

  		return;
  	}
  
  	/* handle oob callback */

  	if (priv->dp_port_num == serial_priv->ds_oob_port_num) {

  		dev_dbg(&port->dev, "digi_write_bulk_callback: oob callback
  ");

  		spin_lock(&priv->dp_port_lock);

  		priv->dp_write_urb_in_use = 0;

  		wake_up_interruptible(&port->write_wait);
  		spin_unlock(&priv->dp_port_lock);

  		return;
  	}

  	/* try to send any buffered data on this port */

  	spin_lock(&priv->dp_port_lock);

  	priv->dp_write_urb_in_use = 0;

  	if (priv->dp_out_buf_len > 0) {

  		*((unsigned char *)(port->write_urb->transfer_buffer))
  			= (unsigned char)DIGI_CMD_SEND_DATA;

  		*((unsigned char *)(port->write_urb->transfer_buffer) + 1)

  			= (unsigned char)priv->dp_out_buf_len;

  		port->write_urb->transfer_buffer_length =
  						priv->dp_out_buf_len + 2;

  		memcpy(port->write_urb->transfer_buffer + 2, priv->dp_out_buf,

  			priv->dp_out_buf_len);

  		ret = usb_submit_urb(port->write_urb, GFP_ATOMIC);
  		if (ret == 0) {

  			priv->dp_write_urb_in_use = 1;
  			priv->dp_out_buf_len = 0;
  		}

  	}

  	/* wake up processes sleeping on writes immediately */

  	tty_port_tty_wakeup(&port->port);

  	/* also queue up a wakeup at scheduler time, in case we */
  	/* lost the race in write_chan(). */
  	schedule_work(&priv->dp_wakeup_work);

  	spin_unlock(&priv->dp_port_lock);

  	if (ret && ret != -EPERM)

  		dev_err_console(port,

  			"%s: usb_submit_urb failed, ret=%d, port=%d
  ",

  			__func__, ret, priv->dp_port_num);

  }

  static int digi_write_room(struct tty_struct *tty)

  {

  	struct usb_serial_port *port = tty->driver_data;

  	struct digi_port *priv = usb_get_serial_port_data(port);

  	int room;

  	unsigned long flags = 0;

  	spin_lock_irqsave(&priv->dp_port_lock, flags);

  	if (priv->dp_write_urb_in_use)

  		room = 0;
  	else
  		room = port->bulk_out_size - 2 - priv->dp_out_buf_len;

  	spin_unlock_irqrestore(&priv->dp_port_lock, flags);

  	dev_dbg(&port->dev, "digi_write_room: port=%d, room=%d
  ", priv->dp_port_num, room);

  	return room;

  
  }

  static int digi_chars_in_buffer(struct tty_struct *tty)

  {

  	struct usb_serial_port *port = tty->driver_data;

  	struct digi_port *priv = usb_get_serial_port_data(port);

  	if (priv->dp_write_urb_in_use) {

  		dev_dbg(&port->dev, "digi_chars_in_buffer: port=%d, chars=%d
  ",

  			priv->dp_port_num, port->bulk_out_size - 2);
  		/* return(port->bulk_out_size - 2); */
  		return 256;

  	} else {

  		dev_dbg(&port->dev, "digi_chars_in_buffer: port=%d, chars=%d
  ",

  			priv->dp_port_num, priv->dp_out_buf_len);
  		return priv->dp_out_buf_len;

  	}
  
  }

  static void digi_dtr_rts(struct usb_serial_port *port, int on)
  {
  	/* Adjust DTR and RTS */
  	digi_set_modem_signals(port, on * (TIOCM_DTR|TIOCM_RTS), 1);
  }

  static int digi_open(struct tty_struct *tty, struct usb_serial_port *port)

  {

  	int ret;
  	unsigned char buf[32];
  	struct digi_port *priv = usb_get_serial_port_data(port);

  	struct ktermios not_termios;

  	/* be sure the device is started up */

  	if (digi_startup_device(port->serial) != 0)
  		return -ENXIO;

  	/* read modem signals automatically whenever they change */
  	buf[0] = DIGI_CMD_READ_INPUT_SIGNALS;
  	buf[1] = priv->dp_port_num;
  	buf[2] = DIGI_ENABLE;
  	buf[3] = 0;
  
  	/* flush fifos */
  	buf[4] = DIGI_CMD_IFLUSH_FIFO;
  	buf[5] = priv->dp_port_num;
  	buf[6] = DIGI_FLUSH_TX | DIGI_FLUSH_RX;
  	buf[7] = 0;

  	ret = digi_write_oob_command(port, buf, 8, 1);
  	if (ret != 0)

  		dev_dbg(&port->dev, "digi_open: write oob failed, ret=%d
  ", ret);

  
  	/* set termios settings */

  	if (tty) {

  		not_termios.c_cflag = ~tty->termios.c_cflag;
  		not_termios.c_iflag = ~tty->termios.c_iflag;

  		digi_set_termios(tty, port, &not_termios);
  	}

  	return 0;

  }

  static void digi_close(struct usb_serial_port *port)

  {
  	DEFINE_WAIT(wait);
  	int ret;
  	unsigned char buf[32];

  	struct digi_port *priv = usb_get_serial_port_data(port);

  	mutex_lock(&port->serial->disc_mutex);

  	/* if disconnected, just clear flags */

  	if (port->serial->disconnected)

  		goto exit;

  	/* FIXME: Transmit idle belongs in the wait_unti_sent path */
  	digi_transmit_idle(port, DIGI_CLOSE_TIMEOUT);
  
  	/* disable input flow control */
  	buf[0] = DIGI_CMD_SET_INPUT_FLOW_CONTROL;
  	buf[1] = priv->dp_port_num;
  	buf[2] = DIGI_DISABLE;
  	buf[3] = 0;
  
  	/* disable output flow control */
  	buf[4] = DIGI_CMD_SET_OUTPUT_FLOW_CONTROL;
  	buf[5] = priv->dp_port_num;
  	buf[6] = DIGI_DISABLE;
  	buf[7] = 0;
  
  	/* disable reading modem signals automatically */
  	buf[8] = DIGI_CMD_READ_INPUT_SIGNALS;
  	buf[9] = priv->dp_port_num;
  	buf[10] = DIGI_DISABLE;
  	buf[11] = 0;
  
  	/* disable receive */
  	buf[12] = DIGI_CMD_RECEIVE_ENABLE;
  	buf[13] = priv->dp_port_num;
  	buf[14] = DIGI_DISABLE;
  	buf[15] = 0;
  
  	/* flush fifos */
  	buf[16] = DIGI_CMD_IFLUSH_FIFO;
  	buf[17] = priv->dp_port_num;
  	buf[18] = DIGI_FLUSH_TX | DIGI_FLUSH_RX;
  	buf[19] = 0;
  
  	ret = digi_write_oob_command(port, buf, 20, 0);
  	if (ret != 0)
  		dev_dbg(&port->dev, "digi_close: write oob failed, ret=%d
  ",
  									ret);
  	/* wait for final commands on oob port to complete */
  	prepare_to_wait(&priv->dp_flush_wait, &wait,
  			TASK_INTERRUPTIBLE);
  	schedule_timeout(DIGI_CLOSE_TIMEOUT);
  	finish_wait(&priv->dp_flush_wait, &wait);
  
  	/* shutdown any outstanding bulk writes */
  	usb_kill_urb(port->write_urb);

  exit:

  	spin_lock_irq(&priv->dp_port_lock);

  	priv->dp_write_urb_in_use = 0;

  	wake_up_interruptible(&priv->dp_close_wait);

  	spin_unlock_irq(&priv->dp_port_lock);
  	mutex_unlock(&port->serial->disc_mutex);

  }
  
  
  /*

   *  Digi Startup Device
   *
   *  Starts reads on all ports.  Must be called AFTER startup, with
   *  urbs initialized.  Returns 0 if successful, non-zero error otherwise.
   */

  static int digi_startup_device(struct usb_serial *serial)

  {

  	int i, ret = 0;

  	struct digi_serial *serial_priv = usb_get_serial_data(serial);
  	struct usb_serial_port *port;

  	/* be sure this happens exactly once */

  	spin_lock(&serial_priv->ds_serial_lock);
  	if (serial_priv->ds_device_started) {
  		spin_unlock(&serial_priv->ds_serial_lock);
  		return 0;

  	}
  	serial_priv->ds_device_started = 1;

  	spin_unlock(&serial_priv->ds_serial_lock);

  
  	/* start reading from each bulk in endpoint for the device */
  	/* set USB_DISABLE_SPD flag for write bulk urbs */

  	for (i = 0; i < serial->type->num_ports + 1; i++) {

  		port = serial->port[i];

  		ret = usb_submit_urb(port->read_urb, GFP_KERNEL);
  		if (ret != 0) {

  			dev_err(&port->dev,
  				"%s: usb_submit_urb failed, ret=%d, port=%d
  ",
  				__func__, ret, i);

  			break;
  		}

  	}

  	return ret;

  }

  static int digi_port_init(struct usb_serial_port *port, unsigned port_num)

  {

  	struct digi_port *priv;

  	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
  	if (!priv)
  		return -ENOMEM;

  	spin_lock_init(&priv->dp_port_lock);
  	priv->dp_port_num = port_num;

  	init_waitqueue_head(&priv->dp_transmit_idle_wait);
  	init_waitqueue_head(&priv->dp_flush_wait);
  	init_waitqueue_head(&priv->dp_close_wait);
  	INIT_WORK(&priv->dp_wakeup_work, digi_wakeup_write_lock);
  	priv->dp_port = port;

  	init_waitqueue_head(&port->write_wait);
  
  	usb_set_serial_port_data(port, priv);
  
  	return 0;
  }
  
  static int digi_startup(struct usb_serial *serial)
  {
  	struct digi_serial *serial_priv;
  	int ret;
  
  	serial_priv = kzalloc(sizeof(*serial_priv), GFP_KERNEL);
  	if (!serial_priv)
  		return -ENOMEM;

  	spin_lock_init(&serial_priv->ds_serial_lock);

  	serial_priv->ds_oob_port_num = serial->type->num_ports;
  	serial_priv->ds_oob_port = serial->port[serial_priv->ds_oob_port_num];

  
  	ret = digi_port_init(serial_priv->ds_oob_port,
  						serial_priv->ds_oob_port_num);
  	if (ret) {
  		kfree(serial_priv);
  		return ret;
  	}

  	usb_set_serial_data(serial, serial_priv);

  	return 0;

  }

  static void digi_disconnect(struct usb_serial *serial)

  {

  	int i;

  
  	/* stop reads and writes on all ports */

  	for (i = 0; i < serial->type->num_ports + 1; i++) {

  		usb_kill_urb(serial->port[i]->read_urb);
  		usb_kill_urb(serial->port[i]->write_urb);
  	}

  }
  
  
  static void digi_release(struct usb_serial *serial)
  {

  	struct digi_serial *serial_priv;
  	struct digi_port *priv;
  
  	serial_priv = usb_get_serial_data(serial);
  
  	priv = usb_get_serial_port_data(serial_priv->ds_oob_port);
  	kfree(priv);

  	kfree(serial_priv);

  }

  static int digi_port_probe(struct usb_serial_port *port)
  {

  	return digi_port_init(port, port->port_number);

  }
  
  static int digi_port_remove(struct usb_serial_port *port)
  {
  	struct digi_port *priv;
  
  	priv = usb_get_serial_port_data(port);
  	kfree(priv);
  
  	return 0;
  }

  static void digi_read_bulk_callback(struct urb *urb)

  {

  	struct usb_serial_port *port = urb->context;

  	struct digi_port *priv;
  	struct digi_serial *serial_priv;
  	int ret;

  	int status = urb->status;

  	/* port sanity check, do not resubmit if port is not valid */

  	if (port == NULL)
  		return;
  	priv = usb_get_serial_port_data(port);
  	if (priv == NULL) {
  		dev_err(&port->dev, "%s: port->private is NULL, status=%d
  ",
  			__func__, status);

  		return;
  	}

  	if (port->serial == NULL ||

  		(serial_priv = usb_get_serial_data(port->serial)) == NULL) {

  		dev_err(&port->dev, "%s: serial is bad or serial->private "
  			"is NULL, status=%d
  ", __func__, status);

  		return;
  	}
  
  	/* do not resubmit urb if it has any status error */

  	if (status) {

  		dev_err(&port->dev,
  			"%s: nonzero read bulk status: status=%d, port=%d
  ",
  			__func__, status, priv->dp_port_num);

  		return;
  	}
  
  	/* handle oob or inb callback, do not resubmit if error */

  	if (priv->dp_port_num == serial_priv->ds_oob_port_num) {
  		if (digi_read_oob_callback(urb) != 0)

  			return;
  	} else {

  		if (digi_read_inb_callback(urb) != 0)

  			return;
  	}
  
  	/* continue read */

  	ret = usb_submit_urb(urb, GFP_ATOMIC);

  	if (ret != 0 && ret != -EPERM) {

  		dev_err(&port->dev,
  			"%s: failed resubmitting urb, ret=%d, port=%d
  ",
  			__func__, ret, priv->dp_port_num);

  	}
  
  }

  /*
   *  Digi Read INB Callback
   *
   *  Digi Read INB Callback handles reads on the in band ports, sending
   *  the data on to the tty subsystem.  When called we know port and
   *  port->private are not NULL and port->serial has been validated.
   *  It returns 0 if successful, 1 if successful but the port is
   *  throttled, and -1 if the sanity checks failed.
   */

  static int digi_read_inb_callback(struct urb *urb)

  {

  	struct usb_serial_port *port = urb->context;

  	struct digi_port *priv = usb_get_serial_port_data(port);

  	unsigned char *buf = urb->transfer_buffer;
  	int opcode;
  	int len;
  	int port_status;
  	unsigned char *data;

  	int flag, throttled;

  
  	/* short/multiple packet check */

  	if (urb->actual_length < 2) {
  		dev_warn(&port->dev, "short packet received
  ");
  		return -1;
  	}
  
  	opcode = buf[0];
  	len = buf[1];

  	if (urb->actual_length != len + 2) {

  		dev_err(&port->dev, "malformed packet received: port=%d, opcode=%d, len=%d, actual_length=%u
  ",
  			priv->dp_port_num, opcode, len, urb->actual_length);
  		return -1;
  	}
  
  	if (opcode == DIGI_CMD_RECEIVE_DATA && len < 1) {
  		dev_err(&port->dev, "malformed data packet received
  ");

  		return -1;

  	}

  	spin_lock(&priv->dp_port_lock);

  
  	/* check for throttle; if set, do not resubmit read urb */
  	/* indicate the read chain needs to be restarted on unthrottle */
  	throttled = priv->dp_throttled;

  	if (throttled)

  		priv->dp_throttle_restart = 1;
  
  	/* receive data */

  	if (opcode == DIGI_CMD_RECEIVE_DATA) {

  		port_status = buf[2];
  		data = &buf[3];

  		/* get flag from port_status */

  		flag = 0;
  
  		/* overrun is special, not associated with a char */

  		if (port_status & DIGI_OVERRUN_ERROR)

  			tty_insert_flip_char(&port->port, 0, TTY_OVERRUN);

  
  		/* break takes precedence over parity, */
  		/* which takes precedence over framing errors */

  		if (port_status & DIGI_BREAK_ERROR)

  			flag = TTY_BREAK;

  		else if (port_status & DIGI_PARITY_ERROR)

  			flag = TTY_PARITY;

  		else if (port_status & DIGI_FRAMING_ERROR)

  			flag = TTY_FRAME;

  		/* data length is len-1 (one byte of len is port_status) */

  		--len;

  		if (len > 0) {

  			tty_insert_flip_string_fixed_flag(&port->port, data,
  					flag, len);

  			tty_flip_buffer_push(&port->port);

  		}

  	}

  	spin_unlock(&priv->dp_port_lock);

  	if (opcode == DIGI_CMD_RECEIVE_DISABLE)

  		dev_dbg(&port->dev, "%s: got RECEIVE_DISABLE
  ", __func__);

  	else if (opcode != DIGI_CMD_RECEIVE_DATA)

  		dev_dbg(&port->dev, "%s: unknown opcode: %d
  ", __func__, opcode);

  	return throttled ? 1 : 0;

  
  }

  /*
   *  Digi Read OOB Callback
   *
   *  Digi Read OOB Callback handles reads on the out of band port.
   *  When called we know port and port->private are not NULL and
   *  the port->serial is valid.  It returns 0 if successful, and
   *  -1 if the sanity checks failed.
   */

  static int digi_read_oob_callback(struct urb *urb)

  {

  	struct usb_serial_port *port = urb->context;

  	struct usb_serial *serial = port->serial;

  	struct tty_struct *tty;

  	struct digi_port *priv = usb_get_serial_port_data(port);

  	unsigned char *buf = urb->transfer_buffer;

  	int opcode, line, status, val;
  	int i;

  	unsigned int rts;

  	if (urb->actual_length < 4)
  		return -1;

  	/* handle each oob command */

  	for (i = 0; i < urb->actual_length - 3; i += 4) {

  		opcode = buf[i];
  		line = buf[i + 1];
  		status = buf[i + 2];
  		val = buf[i + 3];

  		dev_dbg(&port->dev, "digi_read_oob_callback: opcode=%d, line=%d, status=%d, val=%d
  ",

  			opcode, line, status, val);

  		if (status != 0 || line >= serial->type->num_ports)

  			continue;
  
  		port = serial->port[line];

  		priv = usb_get_serial_port_data(port);
  		if (priv == NULL)

  			return -1;

  		tty = tty_port_tty_get(&port->port);

  		rts = 0;

  		if (tty)

  			rts = C_CRTSCTS(tty);

  		if (tty && opcode == DIGI_CMD_READ_INPUT_SIGNALS) {

  			spin_lock(&priv->dp_port_lock);

  			/* convert from digi flags to termiox flags */

  			if (val & DIGI_READ_INPUT_SIGNALS_CTS) {

  				priv->dp_modem_signals |= TIOCM_CTS;
  				/* port must be open to use tty struct */

  				if (rts)

  					tty_port_tty_wakeup(&port->port);

  			} else {
  				priv->dp_modem_signals &= ~TIOCM_CTS;
  				/* port must be open to use tty struct */

  			}

  			if (val & DIGI_READ_INPUT_SIGNALS_DSR)

  				priv->dp_modem_signals |= TIOCM_DSR;
  			else
  				priv->dp_modem_signals &= ~TIOCM_DSR;

  			if (val & DIGI_READ_INPUT_SIGNALS_RI)

  				priv->dp_modem_signals |= TIOCM_RI;
  			else
  				priv->dp_modem_signals &= ~TIOCM_RI;

  			if (val & DIGI_READ_INPUT_SIGNALS_DCD)

  				priv->dp_modem_signals |= TIOCM_CD;
  			else
  				priv->dp_modem_signals &= ~TIOCM_CD;

  			spin_unlock(&priv->dp_port_lock);
  		} else if (opcode == DIGI_CMD_TRANSMIT_IDLE) {
  			spin_lock(&priv->dp_port_lock);

  			priv->dp_transmit_idle = 1;

  			wake_up_interruptible(&priv->dp_transmit_idle_wait);
  			spin_unlock(&priv->dp_port_lock);
  		} else if (opcode == DIGI_CMD_IFLUSH_FIFO) {
  			wake_up_interruptible(&priv->dp_flush_wait);

  		}

  		tty_kref_put(tty);

  	}

  	return 0;

  
  }

  module_usb_serial_driver(serial_drivers, id_table_combined);

  MODULE_AUTHOR(DRIVER_AUTHOR);
  MODULE_DESCRIPTION(DRIVER_DESC);

  MODULE_LICENSE("GPL");