USB: serial: add quatech2 usb to serial driver

This supports the Quatech USB 2 usb to serial adapters.

Signed-off-by: Bill Pemberton <wfp5p@virginia.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 1159 insertions, 0 deletions

diff --git a/drivers/usb/serial/Kconfig b/drivers/usb/serial/Kconfig
index 7141d659906..325d2910f9f 100644
--- a/drivers/usb/serial/Kconfig
+++ b/drivers/usb/serial/Kconfig
@@ -669,6 +669,15 @@ config USB_SERIAL_SSU100
 	  To compile this driver as a module, choose M here: the
 	  module will be called ssu100.
 
+config USB_SERIAL_QT2
+	tristate "USB Quatech Serial Driver for USB 2 devices"
+	help
+	  Say Y here if you want to use the Quatech USB 2
+	  serial adapters.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called quatech-serial.
+
 config USB_SERIAL_DEBUG
 	tristate "USB Debugging Device"
 	help
diff --git a/drivers/usb/serial/Makefile b/drivers/usb/serial/Makefile
index 07f198ee048..1dc483a8bfc 100644
--- a/drivers/usb/serial/Makefile
+++ b/drivers/usb/serial/Makefile
@@ -49,6 +49,7 @@ obj-$(CONFIG_USB_SERIAL_OTI6858)		+= oti6858.o
 obj-$(CONFIG_USB_SERIAL_PL2303)			+= pl2303.o
 obj-$(CONFIG_USB_SERIAL_QCAUX)			+= qcaux.o
 obj-$(CONFIG_USB_SERIAL_QUALCOMM)		+= qcserial.o
+obj-$(CONFIG_USB_SERIAL_QT2)			+= quatech2.o
 obj-$(CONFIG_USB_SERIAL_SAFE)			+= safe_serial.o
 obj-$(CONFIG_USB_SERIAL_SIEMENS_MPI)		+= siemens_mpi.o
 obj-$(CONFIG_USB_SERIAL_SIERRAWIRELESS)		+= sierra.o
diff --git a/drivers/usb/serial/quatech2.c b/drivers/usb/serial/quatech2.c
new file mode 100644
index 00000000000..3aa63f1f6df
--- /dev/null
+++ b/drivers/usb/serial/quatech2.c
@@ -0,0 +1,1149 @@
+/*
+ * usb-serial driver for Quatech USB 2 devices
+ *
+ *
+ *  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/init.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>
+
+static bool debug;
+
+/* 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_WRITE_BUFFER_SIZE   512  /* size of write buffer */
+#define QT2_WRITE_CONTROL_SIZE  5    /* control bytes used for a write */
+
+/* Version Information */
+#define DRIVER_VERSION "v0.1"
+#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[512];
+};
+
+struct qt2_port_private {
+	bool is_open;
+	u8   device_port;
+
+	spinlock_t urb_lock;
+	bool       urb_in_use;
+	struct urb *write_urb;
+	char       write_buffer[QT2_WRITE_BUFFER_SIZE];
+
+	spinlock_t  lock;
+	u8          shadowLSR;
+	u8          shadowMSR;
+
+	wait_queue_head_t   delta_msr_wait; /* Used for TIOCMIWAIT */
+	struct async_icount icount;
+
+	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)
+{
+	int i;
+
+	kfree(usb_get_serial_data(serial));
+
+	for (i = 0; i < serial->num_ports; i++)
+		kfree(usb_get_serial_port_data(serial->port[i]));
+}
+
+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\n");
+		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\n",
+			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\n");
+
+	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\n",
+			__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\n",
+			__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\n",
+			__func__, status);
+
+}
+
+static int qt2_open(struct tty_struct *tty, struct usb_serial_port *port)
+{
+	struct usb_serial *serial;
+	struct qt2_serial_private *serial_priv;
+	struct qt2_port_private *port_priv;
+	u8 *data;
+	u16 device_port;
+	int status;
+	unsigned long flags;
+
+	device_port = (u16) (port->number - port->serial->minor);
+
+	serial = port->serial;
+
+	port_priv = usb_get_serial_port_data(port);
+	serial_priv = usb_get_serial_data(serial);
+
+	/* 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\n",
+			__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 for port %i (%i)\n",
+			__func__, port->number, device_port);
+		return status;
+	}
+
+	port_priv->is_open = true;
+	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_serial_private *serial_priv;
+	struct qt2_port_private *port_priv;
+	unsigned long flags;
+	int i;
+
+	serial = port->serial;
+	serial_priv = usb_get_serial_data(serial);
+	port_priv = usb_get_serial_port_data(port);
+
+	port_priv->is_open = false;
+
+	spin_lock_irqsave(&port_priv->urb_lock, flags);
+	if (port_priv->write_urb->status == -EINPROGRESS)
+		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\n",
+			__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\n",
+			__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\n",
+			__func__, i);
+
+}
+
+static void qt2_disconnect(struct usb_serial *serial)
+{
+	struct qt2_serial_private *serial_priv = usb_get_serial_data(serial);
+	struct qt2_port_private *port_priv;
+	int i;
+
+	if (serial_priv->read_urb->status == -EINPROGRESS)
+		usb_kill_urb(serial_priv->read_urb);
+
+	usb_free_urb(serial_priv->read_urb);
+
+	for (i = 0; i < serial->num_ports; i++) {
+		port_priv = usb_get_serial_port_data(serial->port[i]);
+
+		if (port_priv->write_urb->status == -EINPROGRESS)
+			usb_kill_urb(port_priv->write_urb);
+		usb_free_urb(port_priv->write_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->serial->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 wait_modem_info(struct usb_serial_port *port, unsigned int arg)
+{
+	struct qt2_port_private *priv = usb_get_serial_port_data(port);
+	struct async_icount prev, cur;
+	unsigned long flags;
+
+	spin_lock_irqsave(&priv->lock, flags);
+	prev = priv->icount;
+	spin_unlock_irqrestore(&priv->lock, flags);
+
+	while (1) {
+		wait_event_interruptible(priv->delta_msr_wait,
+					 ((priv->icount.rng != prev.rng) ||
+					  (priv->icount.dsr != prev.dsr) ||
+					  (priv->icount.dcd != prev.dcd) ||
+					  (priv->icount.cts != prev.cts)));
+
+		if (signal_pending(current))
+			return -ERESTARTSYS;
+
+		spin_lock_irqsave(&priv->lock, flags);
+		cur = priv->icount;
+		spin_unlock_irqrestore(&priv->lock, flags);
+
+		if ((prev.rng == cur.rng) &&
+		    (prev.dsr == cur.dsr) &&
+		    (prev.dcd == cur.dcd) &&
+		    (prev.cts == cur.cts))
+			return -EIO;
+
+		if ((arg & TIOCM_RNG && (prev.rng != cur.rng)) ||
+		    (arg & TIOCM_DSR && (prev.dsr != cur.dsr)) ||
+		    (arg & TIOCM_CD && (prev.dcd != cur.dcd)) ||
+		    (arg & TIOCM_CTS && (prev.cts != cur.cts)))
+			return 0;
+	}
+	return 0;
+}
+
+static int qt2_get_icount(struct tty_struct *tty,
+			  struct serial_icounter_struct *icount)
+{
+	struct usb_serial_port *port = tty->driver_data;
+	struct qt2_port_private *priv = usb_get_serial_port_data(port);
+	struct async_icount cnow = priv->icount;
+
+	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 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);
+
+	case TIOCMIWAIT:
+		return wait_modem_info(port, 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;
+}
+
+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;
+	struct tty_struct *tty;
+	bool escapeflag;
+	unsigned char *ch;
+	int i;
+	unsigned char newport;
+	int len = urb->actual_length;
+
+	if (!len)
+		return;
+
+	ch = urb->transfer_buffer;
+	tty = NULL;
+	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);
+
+	if (port_priv->is_open)
+		tty = tty_port_tty_get(&port->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\n",
+						__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\n",
+						 __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\n",
+						 __func__);
+					break;
+				}
+				if (tty) {
+					tty_flip_buffer_push(tty);
+					tty_kref_put(tty);
+				}
+
+				newport = *(ch + 3);
+
+				if (newport > serial->num_ports) {
+					dev_err(&port->dev,
+						"%s - port change to invalid port: %i\n",
+						__func__, newport);
+					break;
+				}
+
+				serial_priv->current_port = newport;
+				port = serial->port[serial_priv->current_port];
+				port_priv = usb_get_serial_port_data(port);
+				if (port_priv->is_open)
+					tty = tty_port_tty_get(&port->port);
+				else
+					tty = NULL;
+				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(tty, 2);
+				tty_insert_flip_string(tty, ch, 2);
+				i += 2;
+				escapeflag = true;
+				break;
+			default:
+				dev_warn(&port->dev,
+					 "%s - unsupported command %i\n",
+					 __func__, *(ch + 2));
+				break;
+			}
+			if (escapeflag)
+				continue;
+		}
+
+		if (tty) {
+			tty_buffer_request_room(tty, 1);
+			tty_insert_flip_string(tty, ch, 1);
+		}
+	}
+
+	if (tty) {
+		tty_flip_buffer_push(tty);
+		tty_kref_put(tty);
+	}
+}
+
+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\n", __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\n",
+			__func__, status);
+}
+
+static int qt2_setup_urbs(struct usb_serial *serial)
+{
+	struct usb_serial_port *port;
+	struct usb_serial_port *port0;
+	struct qt2_serial_private *serial_priv;
+	struct qt2_port_private *port_priv;
+	int pcount, 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) {
+		dev_err(&serial->dev->dev, "No free urbs available\n");
+		return -ENOMEM;
+	}
+
+	usb_fill_bulk_urb(serial_priv->read_urb, serial->dev,
+			  usb_rcvbulkpipe(serial->dev,
+					  port0->bulk_in_endpointAddress),
+			  serial_priv->read_buffer,
+			  sizeof(serial_priv->read_buffer),
+			  qt2_read_bulk_callback, serial);
+
+	/* setup write_urb for each port */
+	for (pcount = 0; pcount < serial->num_ports; pcount++) {
+
+		port = serial->port[pcount];
+		port_priv = usb_get_serial_port_data(port);
+
+		port_priv->write_urb = usb_alloc_urb(0, GFP_KERNEL);
+		if (!port_priv->write_urb) {
+			dev_err(&serial->dev->dev,
+				"failed to alloc write_urb for port %i\n",
+				pcount);
+			return -ENOMEM;
+		}
+
+		usb_fill_bulk_urb(port_priv->write_urb,
+				  serial->dev,
+				  usb_sndbulkpipe(serial->dev,
+						  port0->
+						  bulk_out_endpointAddress),
+				  port_priv->write_buffer,
+				  sizeof(port_priv->write_buffer),
+				  qt2_write_bulk_callback, port);
+	}
+
+	status = usb_submit_urb(serial_priv->read_urb, GFP_KERNEL);
+	if (status != 0) {
+		dev_err(&serial->dev->dev,
+			"%s - submit read urb failed %i\n", __func__, status);
+		return status;
+	}
+
+	return 0;
+
+}
+
+static int qt2_attach(struct usb_serial *serial)
+{
+	struct qt2_serial_private *serial_priv;
+	struct qt2_port_private *port_priv;
+	int status, pcount;
+
+	/* 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\n", __func__, status);
+		return status;
+	}
+
+	serial_priv = kzalloc(sizeof(*serial_priv), GFP_KERNEL);
+	if (!serial_priv) {
+		dev_err(&serial->dev->dev, "%s - Out of memory\n", __func__);
+		return -ENOMEM;
+	}
+
+	usb_set_serial_data(serial, serial_priv);
+
+	for (pcount = 0; pcount < serial->num_ports; pcount++) {
+		port_priv = kzalloc(sizeof(*port_priv), GFP_KERNEL);
+		if (!port_priv) {
+			dev_err(&serial->dev->dev,
+				"%s- kmalloc(%Zd) failed.\n", __func__,
+				sizeof(*port_priv));
+			pcount--;
+			status = -ENOMEM;
+			goto attach_failed;
+		}
+
+		spin_lock_init(&port_priv->lock);
+		spin_lock_init(&port_priv->urb_lock);
+		init_waitqueue_head(&port_priv->delta_msr_wait);
+
+		port_priv->port = serial->port[pcount];
+
+		usb_set_serial_port_data(serial->port[pcount], port_priv);
+	}
+
+	status = qt2_setup_urbs(serial);
+	if (status != 0)
+		goto attach_failed;
+
+	return 0;
+
+attach_failed:
+	for (/* empty */; pcount >= 0; pcount--) {
+		port_priv = usb_get_serial_port_data(serial->port[pcount]);
+		kfree(port_priv);
+	}
+	kfree(serial_priv);
+	return status;
+}
+
+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);
+
+	if (!port_priv->is_open) {
+		dev_err(&port->dev,
+			"%s - port is not open\n", __func__);
+		return;
+	}
+
+	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\n", __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);
+
+	mutex_lock(&port->serial->disc_mutex);
+	if (!port->serial->disconnected) {
+		/* Disable flow control */
+		if (!on && qt2_setregister(dev, port_priv->device_port,
+					   UART_MCR, 0) < 0)
+			dev_warn(&port->dev, "error from flowcontrol urb\n");
+		/* 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);
+	}
+	mutex_unlock(&port->serial->disc_mutex);
+}
+
+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_priv->icount.cts++;
+
+		if (newMSR & UART_MSR_DDSR)
+			port_priv->icount.dsr++;
+
+		if (newMSR & UART_MSR_DDCD)
+			port_priv->icount.dcd++;
+
+		if (newMSR & UART_MSR_TERI)
+			port_priv->icount.rng++;
+
+		wake_up_interruptible(&port_priv->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_priv->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\n", __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) {
+		printk(KERN_INFO "qt2_write - urb is in use\n");
+		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,
+	.dtr_rts             = qt2_dtr_rts,
+	.break_ctl           = qt2_break_ctl,
+	.tiocmget            = qt2_tiocmget,
+	.tiocmset            = qt2_tiocmset,
+	.get_icount	     = qt2_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");
+
+module_param(debug, bool, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(debug, "Debug enabled or not");