/*
   * usb-serial driver for Quatech USB 2 devices
   *
   * Copyright (C) 2012 Bill Pemberton (wfp5p@virginia.edu)
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License version 2
   * as published by the Free Software Foundation.
   *
   *
   *  These devices all have only 1 bulk in and 1 bulk out that is shared
   *  for all serial ports.
   *
   */
  
  #include <asm/unaligned.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/serial.h>
  #include <linux/usb.h>
  #include <linux/usb/serial.h>
  #include <linux/serial_reg.h>
  #include <linux/uaccess.h>
  
  /* default urb timeout for usb operations */
  #define QT2_USB_TIMEOUT USB_CTRL_SET_TIMEOUT
  
  #define QT_OPEN_CLOSE_CHANNEL       0xca
  #define QT_SET_GET_DEVICE           0xc2
  #define QT_SET_GET_REGISTER         0xc0
  #define QT_GET_SET_PREBUF_TRIG_LVL  0xcc
  #define QT_SET_ATF                  0xcd
  #define QT_TRANSFER_IN              0xc0
  #define QT_HW_FLOW_CONTROL_MASK     0xc5
  #define QT_SW_FLOW_CONTROL_MASK     0xc6
  #define QT2_BREAK_CONTROL	    0xc8
  #define QT2_GET_SET_UART            0xc1
  #define QT2_FLUSH_DEVICE	    0xc4
  #define QT2_GET_SET_QMCR            0xe1
  #define QT2_QMCR_RS232              0x40
  #define QT2_QMCR_RS422              0x10
  
  #define  SERIAL_CRTSCTS ((UART_MCR_RTS << 8) | UART_MSR_CTS)
  
  #define  SERIAL_EVEN_PARITY         (UART_LCR_PARITY | UART_LCR_EPAR)
  
  /* status bytes for the device */
  #define QT2_CONTROL_BYTE    0x1b
  #define QT2_LINE_STATUS     0x00  /* following 1 byte is line status */
  #define QT2_MODEM_STATUS    0x01  /* following 1 byte is modem status */
  #define QT2_XMIT_HOLD       0x02  /* following 2 bytes are ?? */
  #define QT2_CHANGE_PORT     0x03  /* following 1 byte is port to change to */
  #define QT2_REC_FLUSH       0x04  /* no following info */
  #define QT2_XMIT_FLUSH      0x05  /* no following info */
  #define QT2_CONTROL_ESCAPE  0xff  /* pass through previous 2 control bytes */
  
  #define  MAX_BAUD_RATE              921600
  #define  DEFAULT_BAUD_RATE          9600
  
  #define QT2_READ_BUFFER_SIZE    512  /* size of read buffer */
  #define QT2_WRITE_BUFFER_SIZE   512  /* size of write buffer */
  #define QT2_WRITE_CONTROL_SIZE  5    /* control bytes used for a write */
  
  #define DRIVER_DESC "Quatech 2nd gen USB to Serial Driver"
  
  #define	USB_VENDOR_ID_QUATECH	0x061d
  #define QUATECH_SSU2_100	0xC120	/* RS232 single port */
  #define QUATECH_DSU2_100	0xC140	/* RS232 dual port */
  #define QUATECH_DSU2_400	0xC150	/* RS232/422/485 dual port */
  #define QUATECH_QSU2_100	0xC160	/* RS232 four port */
  #define QUATECH_QSU2_400	0xC170	/* RS232/422/485 four port */
  #define QUATECH_ESU2_100	0xC1A0	/* RS232 eight port */
  #define QUATECH_ESU2_400	0xC180	/* RS232/422/485 eight port */
  
  struct qt2_device_detail {
  	int product_id;
  	int num_ports;
  };
  
  #define QT_DETAILS(prod, ports)	\
  	.product_id = (prod),   \
  	.num_ports = (ports)
  
  static const struct qt2_device_detail qt2_device_details[] = {
  	{QT_DETAILS(QUATECH_SSU2_100, 1)},
  	{QT_DETAILS(QUATECH_DSU2_400, 2)},
  	{QT_DETAILS(QUATECH_DSU2_100, 2)},
  	{QT_DETAILS(QUATECH_QSU2_400, 4)},
  	{QT_DETAILS(QUATECH_QSU2_100, 4)},
  	{QT_DETAILS(QUATECH_ESU2_400, 8)},
  	{QT_DETAILS(QUATECH_ESU2_100, 8)},
  	{QT_DETAILS(0, 0)}	/* Terminating entry */
  };
  
  static const struct usb_device_id id_table[] = {
  	{USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_SSU2_100)},
  	{USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_DSU2_100)},
  	{USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_DSU2_400)},
  	{USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_QSU2_100)},
  	{USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_QSU2_400)},
  	{USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_ESU2_100)},
  	{USB_DEVICE(USB_VENDOR_ID_QUATECH, QUATECH_ESU2_400)},
  	{}			/* Terminating entry */
  };
  MODULE_DEVICE_TABLE(usb, id_table);
  
  struct qt2_serial_private {
  	unsigned char current_port;  /* current port for incoming data */
  
  	struct urb	*read_urb;   /* shared among all ports */
  	char		*read_buffer;
  };
  
  struct qt2_port_private {
  	u8   device_port;
  
  	spinlock_t urb_lock;
  	bool       urb_in_use;
  	struct urb *write_urb;
  	char       *write_buffer;
  
  	spinlock_t  lock;
  	u8          shadowLSR;
  	u8          shadowMSR;
  
  	struct usb_serial_port *port;
  };
  
  static void qt2_update_lsr(struct usb_serial_port *port, unsigned char *ch);
  static void qt2_update_msr(struct usb_serial_port *port, unsigned char *ch);
  static void qt2_write_bulk_callback(struct urb *urb);
  static void qt2_read_bulk_callback(struct urb *urb);
  
  static void qt2_release(struct usb_serial *serial)
  {
  	struct qt2_serial_private *serial_priv;
  
  	serial_priv = usb_get_serial_data(serial);
  
  	usb_free_urb(serial_priv->read_urb);
  	kfree(serial_priv->read_buffer);
  	kfree(serial_priv);
  }
  
  static inline int calc_baud_divisor(int baudrate)
  {
  	int divisor, rem;
  
  	divisor = MAX_BAUD_RATE / baudrate;
  	rem = MAX_BAUD_RATE % baudrate;
  	/* Round to nearest divisor */
  	if (((rem * 2) >= baudrate) && (baudrate != 110))
  		divisor++;
  
  	return divisor;
  }
  
  static inline int qt2_set_port_config(struct usb_device *dev,
  				      unsigned char port_number,
  				      u16 baudrate, u16 lcr)
  {
  	int divisor = calc_baud_divisor(baudrate);
  	u16 index = ((u16) (lcr << 8) | (u16) (port_number));
  
  	return usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
  			       QT2_GET_SET_UART, 0x40,
  			       divisor, index, NULL, 0, QT2_USB_TIMEOUT);
  }
  
  static inline int qt2_control_msg(struct usb_device *dev,
  				  u8 request, u16 data, u16 index)
  {
  	return usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
  			       request, 0x40, data, index,
  			       NULL, 0, QT2_USB_TIMEOUT);
  }
  
  static inline int qt2_setdevice(struct usb_device *dev, u8 *data)
  {
  	u16 x = ((u16) (data[1] << 8) | (u16) (data[0]));
  
  	return qt2_control_msg(dev, QT_SET_GET_DEVICE, x, 0);
  }
  
  
  static inline int qt2_getdevice(struct usb_device *dev, u8 *data)
  {
  	return usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
  			       QT_SET_GET_DEVICE, 0xc0, 0, 0,
  			       data, 3, QT2_USB_TIMEOUT);
  }
  
  static inline int qt2_getregister(struct usb_device *dev,
  				  u8 uart,
  				  u8 reg,
  				  u8 *data)
  {
  	return usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
  			       QT_SET_GET_REGISTER, 0xc0, reg,
  			       uart, data, sizeof(*data), QT2_USB_TIMEOUT);
  
  }
  
  static inline int qt2_setregister(struct usb_device *dev,
  				  u8 uart, u8 reg, u16 data)
  {
  	u16 value = (data << 8) | reg;
  
  	return usb_control_msg(dev, usb_sndctrlpipe(dev, 0),
  			       QT_SET_GET_REGISTER, 0x40, value, uart,
  			       NULL, 0, QT2_USB_TIMEOUT);
  }
  
  static inline int update_mctrl(struct qt2_port_private *port_priv,
  			       unsigned int set, unsigned int clear)
  {
  	struct usb_serial_port *port = port_priv->port;
  	struct usb_device *dev = port->serial->dev;
  	unsigned urb_value;
  	int status;
  
  	if (((set | clear) & (TIOCM_DTR | TIOCM_RTS)) == 0) {
  		dev_dbg(&port->dev,
  			"update_mctrl - DTR|RTS not being set|cleared
  ");
  		return 0;	/* no change */
  	}
  
  	clear &= ~set;	/* 'set' takes precedence over 'clear' */
  	urb_value = 0;
  	if (set & TIOCM_DTR)
  		urb_value |= UART_MCR_DTR;
  	if (set & TIOCM_RTS)
  		urb_value |= UART_MCR_RTS;
  
  	status = qt2_setregister(dev, port_priv->device_port, UART_MCR,
  				 urb_value);
  	if (status < 0)
  		dev_err(&port->dev,
  			"update_mctrl - Error from MODEM_CTRL urb: %i
  ",
  			status);
  	return status;
  }
  
  static int qt2_calc_num_ports(struct usb_serial *serial)
  {
  	struct qt2_device_detail d;
  	int i;
  
  	for (i = 0; d = qt2_device_details[i], d.product_id != 0; i++) {
  		if (d.product_id == le16_to_cpu(serial->dev->descriptor.idProduct))
  			return d.num_ports;
  	}
  
  	/* we didn't recognize the device */
  	dev_err(&serial->dev->dev,
  		 "don't know the number of ports, assuming 1
  ");
  
  	return 1;
  }
  
  static void qt2_set_termios(struct tty_struct *tty,
  			    struct usb_serial_port *port,
  			    struct ktermios *old_termios)
  {
  	struct usb_device *dev = port->serial->dev;
  	struct qt2_port_private *port_priv;
  	struct ktermios *termios = &tty->termios;
  	u16 baud;
  	unsigned int cflag = termios->c_cflag;
  	u16 new_lcr = 0;
  	int status;
  
  	port_priv = usb_get_serial_port_data(port);
  
  	if (cflag & PARENB) {
  		if (cflag & PARODD)
  			new_lcr |= UART_LCR_PARITY;
  		else
  			new_lcr |= SERIAL_EVEN_PARITY;
  	}
  
  	switch (cflag & CSIZE) {
  	case CS5:
  		new_lcr |= UART_LCR_WLEN5;
  		break;
  	case CS6:
  		new_lcr |= UART_LCR_WLEN6;
  		break;
  	case CS7:
  		new_lcr |= UART_LCR_WLEN7;
  		break;
  	default:
  	case CS8:
  		new_lcr |= UART_LCR_WLEN8;
  		break;
  	}
  
  	baud = tty_get_baud_rate(tty);
  	if (!baud)
  		baud = 9600;
  
  	status = qt2_set_port_config(dev, port_priv->device_port, baud,
  				     new_lcr);
  	if (status < 0)
  		dev_err(&port->dev, "%s - qt2_set_port_config failed: %i
  ",
  			__func__, status);
  
  	if (cflag & CRTSCTS)
  		status = qt2_control_msg(dev, QT_HW_FLOW_CONTROL_MASK,
  					 SERIAL_CRTSCTS,
  					 port_priv->device_port);
  	else
  		status = qt2_control_msg(dev, QT_HW_FLOW_CONTROL_MASK,
  					 0, port_priv->device_port);
  	if (status < 0)
  		dev_err(&port->dev, "%s - set HW flow control failed: %i
  ",
  			__func__, status);
  
  	if (I_IXOFF(tty) || I_IXON(tty)) {
  		u16 x = ((u16) (START_CHAR(tty) << 8) | (u16) (STOP_CHAR(tty)));
  
  		status = qt2_control_msg(dev, QT_SW_FLOW_CONTROL_MASK,
  					 x, port_priv->device_port);
  	} else
  		status = qt2_control_msg(dev, QT_SW_FLOW_CONTROL_MASK,
  					 0, port_priv->device_port);
  
  	if (status < 0)
  		dev_err(&port->dev, "%s - set SW flow control failed: %i
  ",
  			__func__, status);
  
  }
  
  static int qt2_open(struct tty_struct *tty, struct usb_serial_port *port)
  {
  	struct usb_serial *serial;
  	struct qt2_port_private *port_priv;
  	u8 *data;
  	u16 device_port;
  	int status;
  	unsigned long flags;
  
  	device_port = port->port_number;
  
  	serial = port->serial;
  
  	port_priv = usb_get_serial_port_data(port);
  
  	/* set the port to RS232 mode */
  	status = qt2_control_msg(serial->dev, QT2_GET_SET_QMCR,
  				 QT2_QMCR_RS232, device_port);
  	if (status < 0) {
  		dev_err(&port->dev,
  			"%s failed to set RS232 mode for port %i error %i
  ",
  			__func__, device_port, status);
  		return status;
  	}
  
  	data = kzalloc(2, GFP_KERNEL);
  	if (!data)
  		return -ENOMEM;
  
  	/* open the port */
  	status = usb_control_msg(serial->dev,
  				 usb_rcvctrlpipe(serial->dev, 0),
  				 QT_OPEN_CLOSE_CHANNEL,
  				 0xc0, 0,
  				 device_port, data, 2, QT2_USB_TIMEOUT);
  
  	if (status < 0) {
  		dev_err(&port->dev, "%s - open port failed %i", __func__,
  			status);
  		kfree(data);
  		return status;
  	}
  
  	spin_lock_irqsave(&port_priv->lock, flags);
  	port_priv->shadowLSR = data[0];
  	port_priv->shadowMSR = data[1];
  	spin_unlock_irqrestore(&port_priv->lock, flags);
  
  	kfree(data);
  
  	/* set to default speed and 8bit word size */
  	status = qt2_set_port_config(serial->dev, device_port,
  				     DEFAULT_BAUD_RATE, UART_LCR_WLEN8);
  	if (status < 0) {
  		dev_err(&port->dev, "%s - initial setup failed (%i)
  ",
  			__func__, device_port);
  		return status;
  	}
  
  	port_priv->device_port = (u8) device_port;
  
  	if (tty)
  		qt2_set_termios(tty, port, &tty->termios);
  
  	return 0;
  
  }
  
  static void qt2_close(struct usb_serial_port *port)
  {
  	struct usb_serial *serial;
  	struct qt2_port_private *port_priv;
  	unsigned long flags;
  	int i;
  
  	serial = port->serial;
  	port_priv = usb_get_serial_port_data(port);
  
  	spin_lock_irqsave(&port_priv->urb_lock, flags);
  	usb_kill_urb(port_priv->write_urb);
  	port_priv->urb_in_use = false;
  	spin_unlock_irqrestore(&port_priv->urb_lock, flags);
  
  	/* flush the port transmit buffer */
  	i = usb_control_msg(serial->dev,
  			    usb_rcvctrlpipe(serial->dev, 0),
  			    QT2_FLUSH_DEVICE, 0x40, 1,
  			    port_priv->device_port, NULL, 0, QT2_USB_TIMEOUT);
  
  	if (i < 0)
  		dev_err(&port->dev, "%s - transmit buffer flush failed: %i
  ",
  			__func__, i);
  
  	/* flush the port receive buffer */
  	i = usb_control_msg(serial->dev,
  			    usb_rcvctrlpipe(serial->dev, 0),
  			    QT2_FLUSH_DEVICE, 0x40, 0,
  			    port_priv->device_port, NULL, 0, QT2_USB_TIMEOUT);
  
  	if (i < 0)
  		dev_err(&port->dev, "%s - receive buffer flush failed: %i
  ",
  			__func__, i);
  
  	/* close the port */
  	i = usb_control_msg(serial->dev,
  			    usb_sndctrlpipe(serial->dev, 0),
  			    QT_OPEN_CLOSE_CHANNEL,
  			    0x40, 0,
  			    port_priv->device_port, NULL, 0, QT2_USB_TIMEOUT);
  
  	if (i < 0)
  		dev_err(&port->dev, "%s - close port failed %i
  ",
  			__func__, i);
  }
  
  static void qt2_disconnect(struct usb_serial *serial)
  {
  	struct qt2_serial_private *serial_priv = usb_get_serial_data(serial);
  
  	usb_kill_urb(serial_priv->read_urb);
  }
  
  static int get_serial_info(struct usb_serial_port *port,
  			   struct serial_struct __user *retinfo)
  {
  	struct serial_struct tmp;
  
  	if (!retinfo)
  		return -EFAULT;
  
  	memset(&tmp, 0, sizeof(tmp));
  	tmp.line		= port->minor;
  	tmp.port		= 0;
  	tmp.irq			= 0;
  	tmp.flags		= ASYNC_SKIP_TEST | ASYNC_AUTO_IRQ;
  	tmp.xmit_fifo_size	= port->bulk_out_size;
  	tmp.baud_base		= 9600;
  	tmp.close_delay		= 5*HZ;
  	tmp.closing_wait	= 30*HZ;
  
  	if (copy_to_user(retinfo, &tmp, sizeof(*retinfo)))
  		return -EFAULT;
  	return 0;
  }
  
  static int qt2_ioctl(struct tty_struct *tty,
  		     unsigned int cmd, unsigned long arg)
  {
  	struct usb_serial_port *port = tty->driver_data;
  
  	switch (cmd) {
  	case TIOCGSERIAL:
  		return get_serial_info(port,
  				       (struct serial_struct __user *)arg);
  	default:
  		break;
  	}
  
  	return -ENOIOCTLCMD;
  }
  
  static void qt2_process_status(struct usb_serial_port *port, unsigned char *ch)
  {
  	switch (*ch) {
  	case QT2_LINE_STATUS:
  		qt2_update_lsr(port, ch + 1);
  		break;
  	case QT2_MODEM_STATUS:
  		qt2_update_msr(port, ch + 1);
  		break;
  	}
  }
  
  /* not needed, kept to document functionality */
  static void qt2_process_xmit_empty(struct usb_serial_port *port,
  				   unsigned char *ch)
  {
  	int bytes_written;
  
  	bytes_written = (int)(*ch) + (int)(*(ch + 1) << 4);
  }
  
  /* not needed, kept to document functionality */
  static void qt2_process_flush(struct usb_serial_port *port, unsigned char *ch)
  {
  	return;
  }
  
  static void qt2_process_read_urb(struct urb *urb)
  {
  	struct usb_serial *serial;
  	struct qt2_serial_private *serial_priv;
  	struct usb_serial_port *port;
  	struct qt2_port_private *port_priv;
  	bool escapeflag;
  	unsigned char *ch;
  	int i;
  	unsigned char newport;
  	int len = urb->actual_length;
  
  	if (!len)
  		return;
  
  	ch = urb->transfer_buffer;
  	serial = urb->context;
  	serial_priv = usb_get_serial_data(serial);
  	port = serial->port[serial_priv->current_port];
  	port_priv = usb_get_serial_port_data(port);
  
  	for (i = 0; i < urb->actual_length; i++) {
  		ch = (unsigned char *)urb->transfer_buffer + i;
  		if ((i <= (len - 3)) &&
  		    (*ch == QT2_CONTROL_BYTE) &&
  		    (*(ch + 1) == QT2_CONTROL_BYTE)) {
  			escapeflag = false;
  			switch (*(ch + 2)) {
  			case QT2_LINE_STATUS:
  			case QT2_MODEM_STATUS:
  				if (i > (len - 4)) {
  					dev_warn(&port->dev,
  						 "%s - status message too short
  ",
  						__func__);
  					break;
  				}
  				qt2_process_status(port, ch + 2);
  				i += 3;
  				escapeflag = true;
  				break;
  			case QT2_XMIT_HOLD:
  				if (i > (len - 5)) {
  					dev_warn(&port->dev,
  						 "%s - xmit_empty message too short
  ",
  						 __func__);
  					break;
  				}
  				qt2_process_xmit_empty(port, ch + 3);
  				i += 4;
  				escapeflag = true;
  				break;
  			case QT2_CHANGE_PORT:
  				if (i > (len - 4)) {
  					dev_warn(&port->dev,
  						 "%s - change_port message too short
  ",
  						 __func__);
  					break;
  				}
  				tty_flip_buffer_push(&port->port);
  
  				newport = *(ch + 3);
  
  				if (newport > serial->num_ports) {
  					dev_err(&port->dev,
  						"%s - port change to invalid port: %i
  ",
  						__func__, newport);
  					break;
  				}
  
  				serial_priv->current_port = newport;
  				port = serial->port[serial_priv->current_port];
  				port_priv = usb_get_serial_port_data(port);
  				i += 3;
  				escapeflag = true;
  				break;
  			case QT2_REC_FLUSH:
  			case QT2_XMIT_FLUSH:
  				qt2_process_flush(port, ch + 2);
  				i += 2;
  				escapeflag = true;
  				break;
  			case QT2_CONTROL_ESCAPE:
  				tty_buffer_request_room(&port->port, 2);
  				tty_insert_flip_string(&port->port, ch, 2);
  				i += 2;
  				escapeflag = true;
  				break;
  			default:
  				dev_warn(&port->dev,
  					 "%s - unsupported command %i
  ",
  					 __func__, *(ch + 2));
  				break;
  			}
  			if (escapeflag)
  				continue;
  		}
  
  		tty_buffer_request_room(&port->port, 1);
  		tty_insert_flip_string(&port->port, ch, 1);
  	}
  
  	tty_flip_buffer_push(&port->port);
  }
  
  static void qt2_write_bulk_callback(struct urb *urb)
  {
  	struct usb_serial_port *port;
  	struct qt2_port_private *port_priv;
  
  	port = urb->context;
  	port_priv = usb_get_serial_port_data(port);
  
  	spin_lock(&port_priv->urb_lock);
  
  	port_priv->urb_in_use = false;
  	usb_serial_port_softint(port);
  
  	spin_unlock(&port_priv->urb_lock);
  
  }
  
  static void qt2_read_bulk_callback(struct urb *urb)
  {
  	struct usb_serial *serial = urb->context;
  	int status;
  
  	if (urb->status) {
  		dev_warn(&serial->dev->dev,
  			 "%s - non-zero urb status: %i
  ", __func__,
  			 urb->status);
  		return;
  	}
  
  	qt2_process_read_urb(urb);
  
  	status = usb_submit_urb(urb, GFP_ATOMIC);
  	if (status != 0)
  		dev_err(&serial->dev->dev,
  			"%s - resubmit read urb failed: %i
  ",
  			__func__, status);
  }
  
  static int qt2_setup_urbs(struct usb_serial *serial)
  {
  	struct usb_serial_port *port0;
  	struct qt2_serial_private *serial_priv;
  	int status;
  
  	port0 = serial->port[0];
  
  	serial_priv = usb_get_serial_data(serial);
  	serial_priv->read_urb = usb_alloc_urb(0, GFP_KERNEL);
  	if (!serial_priv->read_urb)
  		return -ENOMEM;
  
  	usb_fill_bulk_urb(serial_priv->read_urb, serial->dev,
  			  usb_rcvbulkpipe(serial->dev,
  					  port0->bulk_in_endpointAddress),
  			  serial_priv->read_buffer,
  			  QT2_READ_BUFFER_SIZE,
  			  qt2_read_bulk_callback, serial);
  
  	status = usb_submit_urb(serial_priv->read_urb, GFP_KERNEL);
  	if (status != 0) {
  		dev_err(&serial->dev->dev,
  			"%s - submit read urb failed %i
  ", __func__, status);
  		usb_free_urb(serial_priv->read_urb);
  		return status;
  	}
  
  	return 0;
  }
  
  static int qt2_attach(struct usb_serial *serial)
  {
  	struct qt2_serial_private *serial_priv;
  	int status;
  
  	/* power on unit */
  	status = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
  				 0xc2, 0x40, 0x8000, 0, NULL, 0,
  				 QT2_USB_TIMEOUT);
  	if (status < 0) {
  		dev_err(&serial->dev->dev,
  			"%s - failed to power on unit: %i
  ", __func__, status);
  		return status;
  	}
  
  	serial_priv = kzalloc(sizeof(*serial_priv), GFP_KERNEL);
  	if (!serial_priv)
  		return -ENOMEM;
  
  	serial_priv->read_buffer = kmalloc(QT2_READ_BUFFER_SIZE, GFP_KERNEL);
  	if (!serial_priv->read_buffer) {
  		status = -ENOMEM;
  		goto err_buf;
  	}
  
  	usb_set_serial_data(serial, serial_priv);
  
  	status = qt2_setup_urbs(serial);
  	if (status != 0)
  		goto attach_failed;
  
  	return 0;
  
  attach_failed:
  	kfree(serial_priv->read_buffer);
  err_buf:
  	kfree(serial_priv);
  	return status;
  }
  
  static int qt2_port_probe(struct usb_serial_port *port)
  {
  	struct usb_serial *serial = port->serial;
  	struct qt2_port_private *port_priv;
  	u8 bEndpointAddress;
  
  	port_priv = kzalloc(sizeof(*port_priv), GFP_KERNEL);
  	if (!port_priv)
  		return -ENOMEM;
  
  	spin_lock_init(&port_priv->lock);
  	spin_lock_init(&port_priv->urb_lock);
  	port_priv->port = port;
  
  	port_priv->write_buffer = kmalloc(QT2_WRITE_BUFFER_SIZE, GFP_KERNEL);
  	if (!port_priv->write_buffer)
  		goto err_buf;
  
  	port_priv->write_urb = usb_alloc_urb(0, GFP_KERNEL);
  	if (!port_priv->write_urb)
  		goto err_urb;
  
  	bEndpointAddress = serial->port[0]->bulk_out_endpointAddress;
  	usb_fill_bulk_urb(port_priv->write_urb, serial->dev,
  				usb_sndbulkpipe(serial->dev, bEndpointAddress),
  				port_priv->write_buffer,
  				QT2_WRITE_BUFFER_SIZE,
  				qt2_write_bulk_callback, port);
  
  	usb_set_serial_port_data(port, port_priv);
  
  	return 0;
  err_urb:
  	kfree(port_priv->write_buffer);
  err_buf:
  	kfree(port_priv);
  	return -ENOMEM;
  }
  
  static int qt2_port_remove(struct usb_serial_port *port)
  {
  	struct qt2_port_private *port_priv;
  
  	port_priv = usb_get_serial_port_data(port);
  	usb_free_urb(port_priv->write_urb);
  	kfree(port_priv->write_buffer);
  	kfree(port_priv);
  
  	return 0;
  }
  
  static int qt2_tiocmget(struct tty_struct *tty)
  {
  	struct usb_serial_port *port = tty->driver_data;
  	struct usb_device *dev = port->serial->dev;
  	struct qt2_port_private *port_priv = usb_get_serial_port_data(port);
  	u8 *d;
  	int r;
  
  	d = kzalloc(2, GFP_KERNEL);
  	if (!d)
  		return -ENOMEM;
  
  	r = qt2_getregister(dev, port_priv->device_port, UART_MCR, d);
  	if (r < 0)
  		goto mget_out;
  
  	r = qt2_getregister(dev, port_priv->device_port, UART_MSR, d + 1);
  	if (r < 0)
  		goto mget_out;
  
  	r = (d[0] & UART_MCR_DTR ? TIOCM_DTR : 0) |
  	    (d[0] & UART_MCR_RTS ? TIOCM_RTS : 0) |
  	    (d[1] & UART_MSR_CTS ? TIOCM_CTS : 0) |
  	    (d[1] & UART_MSR_DCD ? TIOCM_CAR : 0) |
  	    (d[1] & UART_MSR_RI ? TIOCM_RI : 0) |
  	    (d[1] & UART_MSR_DSR ? TIOCM_DSR : 0);
  
  mget_out:
  	kfree(d);
  	return r;
  }
  
  static int qt2_tiocmset(struct tty_struct *tty,
  			unsigned int set, unsigned int clear)
  {
  	struct qt2_port_private *port_priv;
  
  	port_priv = usb_get_serial_port_data(tty->driver_data);
  	return update_mctrl(port_priv, set, clear);
  }
  
  static void qt2_break_ctl(struct tty_struct *tty, int break_state)
  {
  	struct usb_serial_port *port = tty->driver_data;
  	struct qt2_port_private *port_priv;
  	int status;
  	u16 val;
  
  	port_priv = usb_get_serial_port_data(port);
  
  	val = (break_state == -1) ? 1 : 0;
  
  	status = qt2_control_msg(port->serial->dev, QT2_BREAK_CONTROL,
  				 val, port_priv->device_port);
  	if (status < 0)
  		dev_warn(&port->dev,
  			 "%s - failed to send control message: %i
  ", __func__,
  			 status);
  }
  
  
  
  static void qt2_dtr_rts(struct usb_serial_port *port, int on)
  {
  	struct usb_device *dev = port->serial->dev;
  	struct qt2_port_private *port_priv = usb_get_serial_port_data(port);
  
  	/* Disable flow control */
  	if (!on) {
  		if (qt2_setregister(dev, port_priv->device_port,
  					   UART_MCR, 0) < 0)
  			dev_warn(&port->dev, "error from flowcontrol urb
  ");
  	}
  	/* drop RTS and DTR */
  	if (on)
  		update_mctrl(port_priv, TIOCM_DTR | TIOCM_RTS, 0);
  	else
  		update_mctrl(port_priv, 0, TIOCM_DTR | TIOCM_RTS);
  }
  
  static void qt2_update_msr(struct usb_serial_port *port, unsigned char *ch)
  {
  	struct qt2_port_private *port_priv;
  	u8 newMSR = (u8) *ch;
  	unsigned long flags;
  
  	port_priv = usb_get_serial_port_data(port);
  
  	spin_lock_irqsave(&port_priv->lock, flags);
  	port_priv->shadowMSR = newMSR;
  	spin_unlock_irqrestore(&port_priv->lock, flags);
  
  	if (newMSR & UART_MSR_ANY_DELTA) {
  		/* update input line counters */
  		if (newMSR & UART_MSR_DCTS)
  			port->icount.cts++;
  		if (newMSR & UART_MSR_DDSR)
  			port->icount.dsr++;
  		if (newMSR & UART_MSR_DDCD)
  			port->icount.dcd++;
  		if (newMSR & UART_MSR_TERI)
  			port->icount.rng++;
  
  		wake_up_interruptible(&port->port.delta_msr_wait);
  	}
  }
  
  static void qt2_update_lsr(struct usb_serial_port *port, unsigned char *ch)
  {
  	struct qt2_port_private *port_priv;
  	struct async_icount *icount;
  	unsigned long flags;
  	u8 newLSR = (u8) *ch;
  
  	port_priv = usb_get_serial_port_data(port);
  
  	if (newLSR & UART_LSR_BI)
  		newLSR &= (u8) (UART_LSR_OE | UART_LSR_BI);
  
  	spin_lock_irqsave(&port_priv->lock, flags);
  	port_priv->shadowLSR = newLSR;
  	spin_unlock_irqrestore(&port_priv->lock, flags);
  
  	icount = &port->icount;
  
  	if (newLSR & UART_LSR_BRK_ERROR_BITS) {
  
  		if (newLSR & UART_LSR_BI)
  			icount->brk++;
  
  		if (newLSR & UART_LSR_OE)
  			icount->overrun++;
  
  		if (newLSR & UART_LSR_PE)
  			icount->parity++;
  
  		if (newLSR & UART_LSR_FE)
  			icount->frame++;
  	}
  
  }
  
  static int qt2_write_room(struct tty_struct *tty)
  {
  	struct usb_serial_port *port = tty->driver_data;
  	struct qt2_port_private *port_priv;
  	unsigned long flags = 0;
  	int r;
  
  	port_priv = usb_get_serial_port_data(port);
  
  	spin_lock_irqsave(&port_priv->urb_lock, flags);
  
  	if (port_priv->urb_in_use)
  		r = 0;
  	else
  		r = QT2_WRITE_BUFFER_SIZE - QT2_WRITE_CONTROL_SIZE;
  
  	spin_unlock_irqrestore(&port_priv->urb_lock, flags);
  
  	return r;
  }
  
  static int qt2_write(struct tty_struct *tty,
  		     struct usb_serial_port *port,
  		     const unsigned char *buf, int count)
  {
  	struct qt2_port_private *port_priv;
  	struct urb *write_urb;
  	unsigned char *data;
  	unsigned long flags;
  	int status;
  	int bytes_out = 0;
  
  	port_priv = usb_get_serial_port_data(port);
  
  	if (port_priv->write_urb == NULL) {
  		dev_err(&port->dev, "%s - no output urb
  ", __func__);
  		return 0;
  	}
  	write_urb = port_priv->write_urb;
  
  	count = min(count, QT2_WRITE_BUFFER_SIZE - QT2_WRITE_CONTROL_SIZE);
  
  	data = write_urb->transfer_buffer;
  	spin_lock_irqsave(&port_priv->urb_lock, flags);
  	if (port_priv->urb_in_use == true) {
  		dev_err(&port->dev, "qt2_write - urb is in use
  ");
  		goto write_out;
  	}
  
  	*data++ = QT2_CONTROL_BYTE;
  	*data++ = QT2_CONTROL_BYTE;
  	*data++ = port_priv->device_port;
  	put_unaligned_le16(count, data);
  	data += 2;
  	memcpy(data, buf, count);
  
  	write_urb->transfer_buffer_length = count + QT2_WRITE_CONTROL_SIZE;
  
  	status = usb_submit_urb(write_urb, GFP_ATOMIC);
  	if (status == 0) {
  		port_priv->urb_in_use = true;
  		bytes_out += count;
  	}
  
  write_out:
  	spin_unlock_irqrestore(&port_priv->urb_lock, flags);
  	return bytes_out;
  }
  
  
  static struct usb_serial_driver qt2_device = {
  	.driver = {
  		.owner = THIS_MODULE,
  		.name = "quatech-serial",
  	},
  	.description	     = DRIVER_DESC,
  	.id_table	     = id_table,
  	.open		     = qt2_open,
  	.close		     = qt2_close,
  	.write               = qt2_write,
  	.write_room          = qt2_write_room,
  	.calc_num_ports      = qt2_calc_num_ports,
  	.attach              = qt2_attach,
  	.release             = qt2_release,
  	.disconnect          = qt2_disconnect,
  	.port_probe          = qt2_port_probe,
  	.port_remove         = qt2_port_remove,
  	.dtr_rts             = qt2_dtr_rts,
  	.break_ctl           = qt2_break_ctl,
  	.tiocmget            = qt2_tiocmget,
  	.tiocmset            = qt2_tiocmset,
  	.tiocmiwait          = usb_serial_generic_tiocmiwait,
  	.get_icount	     = usb_serial_generic_get_icount,
  	.ioctl               = qt2_ioctl,
  	.set_termios         = qt2_set_termios,
  };
  
  static struct usb_serial_driver *const serial_drivers[] = {
  	&qt2_device, NULL
  };
  
  module_usb_serial_driver(serial_drivers, id_table);
  
  MODULE_DESCRIPTION(DRIVER_DESC);
  MODULE_LICENSE("GPL");