drivers/usb/serial/metro-usb.c - arm/linux-arm64-legacy - Git at Google

 /*
   Some of this code is credited to Linux USB open source files that are
   distributed with Linux.

   Copyright:	2007 Metrologic Instruments. All rights reserved.
   Copyright:	2011 Azimut Ltd. <http://azimutrzn.ru/>
 */

 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/tty.h>
 #include <linux/module.h>
 #include <linux/usb.h>
 #include <linux/errno.h>
 #include <linux/slab.h>
 #include <linux/tty_driver.h>
 #include <linux/tty_flip.h>
 #include <linux/moduleparam.h>
 #include <linux/spinlock.h>
 #include <linux/uaccess.h>
 #include <linux/usb/serial.h>

 /* Version Information */
 #define DRIVER_VERSION "v1.2.0.0"
 #define DRIVER_DESC "Metrologic Instruments Inc. - USB-POS driver"

 /* Product information. */
 #define FOCUS_VENDOR_ID			0x0C2E
 #define FOCUS_PRODUCT_ID_BI		0x0720
 #define FOCUS_PRODUCT_ID_UNI		0x0700

 #define METROUSB_SET_REQUEST_TYPE	0x40
 #define METROUSB_SET_MODEM_CTRL_REQUEST	10
 #define METROUSB_SET_BREAK_REQUEST	0x40
 #define METROUSB_MCR_NONE		0x08	/* Deactivate DTR and RTS. */
 #define METROUSB_MCR_RTS		0x0a	/* Activate RTS. */
 #define METROUSB_MCR_DTR		0x09	/* Activate DTR. */
 #define WDR_TIMEOUT			5000	/* default urb timeout. */

 /* Private data structure. */
 struct metrousb_private {
 	spinlock_t lock;
 	int throttled;
 	unsigned long control_state;
 };

 /* Device table list. */
 static struct usb_device_id id_table[] = {
 	{ USB_DEVICE(FOCUS_VENDOR_ID, FOCUS_PRODUCT_ID_BI) },
 	{ USB_DEVICE(FOCUS_VENDOR_ID, FOCUS_PRODUCT_ID_UNI) },
 	{ }, /* Terminating entry. */
 };
 MODULE_DEVICE_TABLE(usb, id_table);

 /* Input parameter constants. */
 static bool debug;

 /* UNI-Directional mode commands for device configure */
 #define UNI_CMD_OPEN	0x80
 #define UNI_CMD_CLOSE	0xFF

 inline int metrousb_is_unidirectional_mode(struct usb_serial_port *port)
 {
 	__u16 product_id = le16_to_cpu(
 		port->serial->dev->descriptor.idProduct);

 	return product_id == FOCUS_PRODUCT_ID_UNI;
 }

 static int metrousb_send_unidirectional_cmd(u8 cmd, struct usb_serial_port *port)
 {
 	int ret;
 	int actual_len;
 	u8 *buffer_cmd = NULL;

 	if (!metrousb_is_unidirectional_mode(port))
 		return 0;

 	buffer_cmd = kzalloc(sizeof(cmd), GFP_KERNEL);
 	if (!buffer_cmd)
 		return -ENOMEM;

 	*buffer_cmd = cmd;

 	ret = usb_interrupt_msg(port->serial->dev,
 		usb_sndintpipe(port->serial->dev, port->interrupt_out_endpointAddress),
 		buffer_cmd, sizeof(cmd),
 		&actual_len, USB_CTRL_SET_TIMEOUT);

 	kfree(buffer_cmd);

 	if (ret < 0)
 		return ret;
 	else if (actual_len != sizeof(cmd))
 		return -EIO;
 	return 0;
 }

 static void metrousb_read_int_callback(struct urb *urb)
 {
 	struct usb_serial_port *port = urb->context;
 	struct metrousb_private *metro_priv = usb_get_serial_port_data(port);
 	struct tty_struct *tty;
 	unsigned char *data = urb->transfer_buffer;
 	int throttled = 0;
 	int result = 0;
 	unsigned long flags = 0;

 	dev_dbg(&port->dev, "%s\n", __func__);

 	switch (urb->status) {
 	case 0:
 		/* Success status, read from the port. */
 		break;
 	case -ECONNRESET:
 	case -ENOENT:
 	case -ESHUTDOWN:
 		/* urb has been terminated. */
 		dev_dbg(&port->dev,
 			"%s - urb shutting down, error code=%d\n",
 			__func__, urb->status);
 		return;
 	default:
 		dev_dbg(&port->dev,
 			"%s - non-zero urb received, error code=%d\n",
 			__func__, urb->status);
 		goto exit;
 	}


 	/* Set the data read from the usb port into the serial port buffer. */
 	tty = tty_port_tty_get(&port->port);
 	if (!tty) {
 		dev_err(&port->dev, "%s - bad tty pointer - exiting\n",
 			__func__);
 		return;
 	}

 	if (tty && urb->actual_length) {
 		/* Loop through the data copying each byte to the tty layer. */
 		tty_insert_flip_string(tty, data, urb->actual_length);

 		/* Force the data to the tty layer. */
 		tty_flip_buffer_push(tty);
 	}
 	tty_kref_put(tty);

 	/* Set any port variables. */
 	spin_lock_irqsave(&metro_priv->lock, flags);
 	throttled = metro_priv->throttled;
 	spin_unlock_irqrestore(&metro_priv->lock, flags);

 	/* Continue trying to read if set. */
 	if (!throttled) {
 		usb_fill_int_urb(port->interrupt_in_urb, port->serial->dev,
 				 usb_rcvintpipe(port->serial->dev, port->interrupt_in_endpointAddress),
 				 port->interrupt_in_urb->transfer_buffer,
 				 port->interrupt_in_urb->transfer_buffer_length,
 				 metrousb_read_int_callback, port, 1);

 		result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);

 		if (result)
 			dev_err(&port->dev,
 				"%s - failed submitting interrupt in urb, error code=%d\n",
 				__func__, result);
 	}
 	return;

 exit:
 	/* Try to resubmit the urb. */
 	result = usb_submit_urb(urb, GFP_ATOMIC);
 	if (result)
 		dev_err(&port->dev,
 			"%s - failed submitting interrupt in urb, error code=%d\n",
 			__func__, result);
 }

 static void metrousb_write_int_callback(struct urb *urb)
 {
 	struct usb_serial_port *port = urb->context;

 	dev_warn(&port->dev, "%s not implemented yet.\n",
 		__func__);
 }

 static void metrousb_cleanup(struct usb_serial_port *port)
 {
 	dev_dbg(&port->dev, "%s\n", __func__);

 	if (port->serial->dev) {
 		/* Shutdown any interrupt in urbs. */
 		if (port->interrupt_in_urb) {
 			usb_unlink_urb(port->interrupt_in_urb);
 			usb_kill_urb(port->interrupt_in_urb);
 		}

 		/* Send deactivate cmd to device */
 		metrousb_send_unidirectional_cmd(UNI_CMD_CLOSE, port);
 	}
 }

 static int metrousb_open(struct tty_struct *tty, struct usb_serial_port *port)
 {
 	struct usb_serial *serial = port->serial;
 	struct metrousb_private *metro_priv = usb_get_serial_port_data(port);
 	unsigned long flags = 0;
 	int result = 0;

 	dev_dbg(&port->dev, "%s\n", __func__);

 	/* Make sure the urb is initialized. */
 	if (!port->interrupt_in_urb) {
 		dev_err(&port->dev, "%s - interrupt urb not initialized\n",
 			__func__);
 		return -ENODEV;
 	}

 	/* Set the private data information for the port. */
 	spin_lock_irqsave(&metro_priv->lock, flags);
 	metro_priv->control_state = 0;
 	metro_priv->throttled = 0;
 	spin_unlock_irqrestore(&metro_priv->lock, flags);

 	/*
 	 * Force low_latency on so that our tty_push actually forces the data
 	 * through, otherwise it is scheduled, and with high data rates (like
 	 * with OHCI) data can get lost.
 	 */
 	if (tty)
 		tty->low_latency = 1;

 	/* Clear the urb pipe. */
 	usb_clear_halt(serial->dev, port->interrupt_in_urb->pipe);

 	/* Start reading from the device */
 	usb_fill_int_urb(port->interrupt_in_urb, serial->dev,
 			  usb_rcvintpipe(serial->dev, port->interrupt_in_endpointAddress),
 			   port->interrupt_in_urb->transfer_buffer,
 			   port->interrupt_in_urb->transfer_buffer_length,
 			   metrousb_read_int_callback, port, 1);
 	result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);

 	if (result) {
 		dev_err(&port->dev,
 			"%s - failed submitting interrupt in urb, error code=%d\n",
 			__func__, result);
 		goto exit;
 	}

 	/* Send activate cmd to device */
 	result = metrousb_send_unidirectional_cmd(UNI_CMD_OPEN, port);
 	if (result) {
 		dev_err(&port->dev,
 			"%s - failed to configure device for port number=%d, error code=%d\n",
 			__func__, port->number, result);
 		goto exit;
 	}

 	dev_dbg(&port->dev, "%s - port open\n", __func__);
 exit:
 	return result;
 }

 static int metrousb_set_modem_ctrl(struct usb_serial *serial, unsigned int control_state)
 {
 	int retval = 0;
 	unsigned char mcr = METROUSB_MCR_NONE;

 	dev_dbg(&serial->dev->dev, "%s - control state = %d\n",
 		__func__, control_state);

 	/* Set the modem control value. */
 	if (control_state & TIOCM_DTR)
 		mcr |= METROUSB_MCR_DTR;
 	if (control_state & TIOCM_RTS)
 		mcr |= METROUSB_MCR_RTS;

 	/* Send the command to the usb port. */
 	retval = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
 				METROUSB_SET_REQUEST_TYPE, METROUSB_SET_MODEM_CTRL_REQUEST,
 				control_state, 0, NULL, 0, WDR_TIMEOUT);
 	if (retval < 0)
 		dev_err(&serial->dev->dev,
 			"%s - set modem ctrl=0x%x failed, error code=%d\n",
 			__func__, mcr, retval);

 	return retval;
 }

 static void metrousb_shutdown(struct usb_serial *serial)
 {
 	int i = 0;

 	dev_dbg(&serial->dev->dev, "%s\n", __func__);

 	/* Stop reading and writing on all ports. */
 	for (i = 0; i < serial->num_ports; ++i) {
 		/* Close any open urbs. */
 		metrousb_cleanup(serial->port[i]);

 		/* Free memory. */
 		kfree(usb_get_serial_port_data(serial->port[i]));
 		usb_set_serial_port_data(serial->port[i], NULL);

 		dev_dbg(&serial->dev->dev, "%s - freed port number=%d\n",
 			__func__, serial->port[i]->number);
 	}
 }

 static int metrousb_startup(struct usb_serial *serial)
 {
 	struct metrousb_private *metro_priv;
 	struct usb_serial_port *port;
 	int i = 0;

 	dev_dbg(&serial->dev->dev, "%s\n", __func__);

 	/* Loop through the serial ports setting up the private structures.
 	 * Currently we only use one port. */
 	for (i = 0; i < serial->num_ports; ++i) {
 		port = serial->port[i];

 		/* Declare memory. */
 		metro_priv = kzalloc(sizeof(struct metrousb_private), GFP_KERNEL);
 		if (!metro_priv)
 			return -ENOMEM;

 		/* Initialize memory. */
 		spin_lock_init(&metro_priv->lock);
 		usb_set_serial_port_data(port, metro_priv);

 		dev_dbg(&serial->dev->dev, "%s - port number=%d\n ",
 			__func__, port->number);
 	}

 	return 0;
 }

 static void metrousb_throttle(struct tty_struct *tty)
 {
 	struct usb_serial_port *port = tty->driver_data;
 	struct metrousb_private *metro_priv = usb_get_serial_port_data(port);
 	unsigned long flags = 0;

 	dev_dbg(tty->dev, "%s\n", __func__);

 	/* Set the private information for the port to stop reading data. */
 	spin_lock_irqsave(&metro_priv->lock, flags);
 	metro_priv->throttled = 1;
 	spin_unlock_irqrestore(&metro_priv->lock, flags);
 }

 static int metrousb_tiocmget(struct tty_struct *tty)
 {
 	unsigned long control_state = 0;
 	struct usb_serial_port *port = tty->driver_data;
 	struct metrousb_private *metro_priv = usb_get_serial_port_data(port);
 	unsigned long flags = 0;

 	dev_dbg(tty->dev, "%s\n", __func__);

 	spin_lock_irqsave(&metro_priv->lock, flags);
 	control_state = metro_priv->control_state;
 	spin_unlock_irqrestore(&metro_priv->lock, flags);

 	return control_state;
 }

 static int metrousb_tiocmset(struct tty_struct *tty,
 			     unsigned int set, unsigned int clear)
 {
 	struct usb_serial_port *port = tty->driver_data;
 	struct usb_serial *serial = port->serial;
 	struct metrousb_private *metro_priv = usb_get_serial_port_data(port);
 	unsigned long flags = 0;
 	unsigned long control_state = 0;

 	dev_dbg(tty->dev, "%s - set=%d, clear=%d\n", __func__, set, clear);

 	spin_lock_irqsave(&metro_priv->lock, flags);
 	control_state = metro_priv->control_state;

 	/* Set the RTS and DTR values. */
 	if (set & TIOCM_RTS)
 		control_state |= TIOCM_RTS;
 	if (set & TIOCM_DTR)
 		control_state |= TIOCM_DTR;
 	if (clear & TIOCM_RTS)
 		control_state &= ~TIOCM_RTS;
 	if (clear & TIOCM_DTR)
 		control_state &= ~TIOCM_DTR;

 	metro_priv->control_state = control_state;
 	spin_unlock_irqrestore(&metro_priv->lock, flags);
 	return metrousb_set_modem_ctrl(serial, control_state);
 }

 static void metrousb_unthrottle(struct tty_struct *tty)
 {
 	struct usb_serial_port *port = tty->driver_data;
 	struct metrousb_private *metro_priv = usb_get_serial_port_data(port);
 	unsigned long flags = 0;
 	int result = 0;

 	dev_dbg(tty->dev, "%s\n", __func__);

 	/* Set the private information for the port to resume reading data. */
 	spin_lock_irqsave(&metro_priv->lock, flags);
 	metro_priv->throttled = 0;
 	spin_unlock_irqrestore(&metro_priv->lock, flags);

 	/* Submit the urb to read from the port. */
 	port->interrupt_in_urb->dev = port->serial->dev;
 	result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);
 	if (result)
 		dev_err(tty->dev,
 			"failed submitting interrupt in urb error code=%d\n",
 			result);
 }

 static struct usb_serial_driver metrousb_device = {
 	.driver = {
 		.owner =	THIS_MODULE,
 		.name =		"metro-usb",
 	},
 	.description		= "Metrologic USB to Serial",
 	.id_table		= id_table,
 	.num_ports		= 1,
 	.open			= metrousb_open,
 	.close			= metrousb_cleanup,
 	.read_int_callback	= metrousb_read_int_callback,
 	.write_int_callback	= metrousb_write_int_callback,
 	.attach			= metrousb_startup,
 	.release		= metrousb_shutdown,
 	.throttle		= metrousb_throttle,
 	.unthrottle		= metrousb_unthrottle,
 	.tiocmget		= metrousb_tiocmget,
 	.tiocmset		= metrousb_tiocmset,
 };

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

 module_usb_serial_driver(serial_drivers, id_table);

 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Philip Nicastro");
 MODULE_AUTHOR("Aleksey Babahin <tamerlan311@gmail.com>");
 MODULE_DESCRIPTION(DRIVER_DESC);

 /* Module input parameters */
 module_param(debug, bool, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(debug, "Print debug info (bool 1=on, 0=off)");
	/*
	Some of this code is credited to Linux USB open source files that are
	distributed with Linux.

	Copyright: 2007 Metrologic Instruments. All rights reserved.
	Copyright: 2011 Azimut Ltd. <http://azimutrzn.ru/>
	*/

	#include <linux/kernel.h>
	#include <linux/init.h>
	#include <linux/tty.h>
	#include <linux/module.h>
	#include <linux/usb.h>
	#include <linux/errno.h>
	#include <linux/slab.h>
	#include <linux/tty_driver.h>
	#include <linux/tty_flip.h>
	#include <linux/moduleparam.h>
	#include <linux/spinlock.h>
	#include <linux/uaccess.h>
	#include <linux/usb/serial.h>

	/* Version Information */
	#define DRIVER_VERSION "v1.2.0.0"
	#define DRIVER_DESC "Metrologic Instruments Inc. - USB-POS driver"

	/* Product information. */
	#define FOCUS_VENDOR_ID 0x0C2E
	#define FOCUS_PRODUCT_ID_BI 0x0720
	#define FOCUS_PRODUCT_ID_UNI 0x0700

	#define METROUSB_SET_REQUEST_TYPE 0x40
	#define METROUSB_SET_MODEM_CTRL_REQUEST 10
	#define METROUSB_SET_BREAK_REQUEST 0x40
	#define METROUSB_MCR_NONE 0x08 /* Deactivate DTR and RTS. */
	#define METROUSB_MCR_RTS 0x0a /* Activate RTS. */
	#define METROUSB_MCR_DTR 0x09 /* Activate DTR. */
	#define WDR_TIMEOUT 5000 /* default urb timeout. */

	/* Private data structure. */
	struct metrousb_private {
	spinlock_t lock;
	int throttled;
	unsigned long control_state;
	};

	/* Device table list. */
	static struct usb_device_id id_table[] = {
	{ USB_DEVICE(FOCUS_VENDOR_ID, FOCUS_PRODUCT_ID_BI) },
	{ USB_DEVICE(FOCUS_VENDOR_ID, FOCUS_PRODUCT_ID_UNI) },
	{ }, /* Terminating entry. */
	};
	MODULE_DEVICE_TABLE(usb, id_table);

	/* Input parameter constants. */
	static bool debug;

	/* UNI-Directional mode commands for device configure */
	#define UNI_CMD_OPEN 0x80
	#define UNI_CMD_CLOSE 0xFF

	inline int metrousb_is_unidirectional_mode(struct usb_serial_port *port)
	{
	__u16 product_id = le16_to_cpu(
	port->serial->dev->descriptor.idProduct);

	return product_id == FOCUS_PRODUCT_ID_UNI;
	}

	static int metrousb_send_unidirectional_cmd(u8 cmd, struct usb_serial_port *port)
	{
	int ret;
	int actual_len;
	u8 *buffer_cmd = NULL;

	if (!metrousb_is_unidirectional_mode(port))
	return 0;

	buffer_cmd = kzalloc(sizeof(cmd), GFP_KERNEL);
	if (!buffer_cmd)
	return -ENOMEM;

	*buffer_cmd = cmd;

	ret = usb_interrupt_msg(port->serial->dev,
	usb_sndintpipe(port->serial->dev, port->interrupt_out_endpointAddress),
	buffer_cmd, sizeof(cmd),
	&actual_len, USB_CTRL_SET_TIMEOUT);

	kfree(buffer_cmd);

	if (ret < 0)
	return ret;
	else if (actual_len != sizeof(cmd))
	return -EIO;
	return 0;
	}

	static void metrousb_read_int_callback(struct urb *urb)
	{
	struct usb_serial_port *port = urb->context;
	struct metrousb_private *metro_priv = usb_get_serial_port_data(port);
	struct tty_struct *tty;
	unsigned char *data = urb->transfer_buffer;
	int throttled = 0;
	int result = 0;
	unsigned long flags = 0;

	dev_dbg(&port->dev, "%s\n", __func__);

	switch (urb->status) {
	case 0:
	/* Success status, read from the port. */
	break;
	case -ECONNRESET:
	case -ENOENT:
	case -ESHUTDOWN:
	/* urb has been terminated. */
	dev_dbg(&port->dev,
	"%s - urb shutting down, error code=%d\n",
	__func__, urb->status);
	return;
	default:
	dev_dbg(&port->dev,
	"%s - non-zero urb received, error code=%d\n",
	__func__, urb->status);
	goto exit;
	}


	/* Set the data read from the usb port into the serial port buffer. */
	tty = tty_port_tty_get(&port->port);
	if (!tty) {
	dev_err(&port->dev, "%s - bad tty pointer - exiting\n",
	__func__);
	return;
	}

	if (tty && urb->actual_length) {
	/* Loop through the data copying each byte to the tty layer. */
	tty_insert_flip_string(tty, data, urb->actual_length);

	/* Force the data to the tty layer. */
	tty_flip_buffer_push(tty);
	}
	tty_kref_put(tty);

	/* Set any port variables. */
	spin_lock_irqsave(&metro_priv->lock, flags);
	throttled = metro_priv->throttled;
	spin_unlock_irqrestore(&metro_priv->lock, flags);

	/* Continue trying to read if set. */
	if (!throttled) {
	usb_fill_int_urb(port->interrupt_in_urb, port->serial->dev,
	usb_rcvintpipe(port->serial->dev, port->interrupt_in_endpointAddress),
	port->interrupt_in_urb->transfer_buffer,
	port->interrupt_in_urb->transfer_buffer_length,
	metrousb_read_int_callback, port, 1);

	result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);

	if (result)
	dev_err(&port->dev,
	"%s - failed submitting interrupt in urb, error code=%d\n",
	__func__, result);
	}
	return;

	exit:
	/* Try to resubmit the urb. */
	result = usb_submit_urb(urb, GFP_ATOMIC);
	if (result)
	dev_err(&port->dev,
	"%s - failed submitting interrupt in urb, error code=%d\n",
	__func__, result);
	}

	static void metrousb_write_int_callback(struct urb *urb)
	{
	struct usb_serial_port *port = urb->context;

	dev_warn(&port->dev, "%s not implemented yet.\n",
	__func__);
	}

	static void metrousb_cleanup(struct usb_serial_port *port)
	{
	dev_dbg(&port->dev, "%s\n", __func__);

	if (port->serial->dev) {
	/* Shutdown any interrupt in urbs. */
	if (port->interrupt_in_urb) {
	usb_unlink_urb(port->interrupt_in_urb);
	usb_kill_urb(port->interrupt_in_urb);
	}

	/* Send deactivate cmd to device */
	metrousb_send_unidirectional_cmd(UNI_CMD_CLOSE, port);
	}
	}

	static int metrousb_open(struct tty_struct tty, struct usb_serial_port port)
	{
	struct usb_serial *serial = port->serial;
	struct metrousb_private *metro_priv = usb_get_serial_port_data(port);
	unsigned long flags = 0;
	int result = 0;

	dev_dbg(&port->dev, "%s\n", __func__);

	/* Make sure the urb is initialized. */
	if (!port->interrupt_in_urb) {
	dev_err(&port->dev, "%s - interrupt urb not initialized\n",
	__func__);
	return -ENODEV;
	}

	/* Set the private data information for the port. */
	spin_lock_irqsave(&metro_priv->lock, flags);
	metro_priv->control_state = 0;
	metro_priv->throttled = 0;
	spin_unlock_irqrestore(&metro_priv->lock, flags);

	/*
	* Force low_latency on so that our tty_push actually forces the data
	* through, otherwise it is scheduled, and with high data rates (like
	* with OHCI) data can get lost.
	*/
	if (tty)
	tty->low_latency = 1;

	/* Clear the urb pipe. */
	usb_clear_halt(serial->dev, port->interrupt_in_urb->pipe);

	/* Start reading from the device */
	usb_fill_int_urb(port->interrupt_in_urb, serial->dev,
	usb_rcvintpipe(serial->dev, port->interrupt_in_endpointAddress),
	port->interrupt_in_urb->transfer_buffer,
	port->interrupt_in_urb->transfer_buffer_length,
	metrousb_read_int_callback, port, 1);
	result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);

	if (result) {
	dev_err(&port->dev,
	"%s - failed submitting interrupt in urb, error code=%d\n",
	__func__, result);
	goto exit;
	}

	/* Send activate cmd to device */
	result = metrousb_send_unidirectional_cmd(UNI_CMD_OPEN, port);
	if (result) {
	dev_err(&port->dev,
	"%s - failed to configure device for port number=%d, error code=%d\n",
	__func__, port->number, result);
	goto exit;
	}

	dev_dbg(&port->dev, "%s - port open\n", __func__);
	exit:
	return result;
	}

	static int metrousb_set_modem_ctrl(struct usb_serial *serial, unsigned int control_state)
	{
	int retval = 0;
	unsigned char mcr = METROUSB_MCR_NONE;

	dev_dbg(&serial->dev->dev, "%s - control state = %d\n",
	__func__, control_state);

	/* Set the modem control value. */
	if (control_state & TIOCM_DTR)
	mcr \|= METROUSB_MCR_DTR;
	if (control_state & TIOCM_RTS)
	mcr \|= METROUSB_MCR_RTS;

	/* Send the command to the usb port. */
	retval = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
	METROUSB_SET_REQUEST_TYPE, METROUSB_SET_MODEM_CTRL_REQUEST,
	control_state, 0, NULL, 0, WDR_TIMEOUT);
	if (retval < 0)
	dev_err(&serial->dev->dev,
	"%s - set modem ctrl=0x%x failed, error code=%d\n",
	__func__, mcr, retval);

	return retval;
	}

	static void metrousb_shutdown(struct usb_serial *serial)
	{
	int i = 0;

	dev_dbg(&serial->dev->dev, "%s\n", __func__);

	/* Stop reading and writing on all ports. */
	for (i = 0; i < serial->num_ports; ++i) {
	/* Close any open urbs. */
	metrousb_cleanup(serial->port[i]);

	/* Free memory. */
	kfree(usb_get_serial_port_data(serial->port[i]));
	usb_set_serial_port_data(serial->port[i], NULL);

	dev_dbg(&serial->dev->dev, "%s - freed port number=%d\n",
	__func__, serial->port[i]->number);
	}
	}

	static int metrousb_startup(struct usb_serial *serial)
	{
	struct metrousb_private *metro_priv;
	struct usb_serial_port *port;
	int i = 0;

	dev_dbg(&serial->dev->dev, "%s\n", __func__);

	/* Loop through the serial ports setting up the private structures.
	* Currently we only use one port. */
	for (i = 0; i < serial->num_ports; ++i) {
	port = serial->port[i];

	/* Declare memory. */
	metro_priv = kzalloc(sizeof(struct metrousb_private), GFP_KERNEL);
	if (!metro_priv)
	return -ENOMEM;

	/* Initialize memory. */
	spin_lock_init(&metro_priv->lock);
	usb_set_serial_port_data(port, metro_priv);

	dev_dbg(&serial->dev->dev, "%s - port number=%d\n ",
	__func__, port->number);
	}

	return 0;
	}

	static void metrousb_throttle(struct tty_struct *tty)
	{
	struct usb_serial_port *port = tty->driver_data;
	struct metrousb_private *metro_priv = usb_get_serial_port_data(port);
	unsigned long flags = 0;

	dev_dbg(tty->dev, "%s\n", __func__);

	/* Set the private information for the port to stop reading data. */
	spin_lock_irqsave(&metro_priv->lock, flags);
	metro_priv->throttled = 1;
	spin_unlock_irqrestore(&metro_priv->lock, flags);
	}

	static int metrousb_tiocmget(struct tty_struct *tty)
	{
	unsigned long control_state = 0;
	struct usb_serial_port *port = tty->driver_data;
	struct metrousb_private *metro_priv = usb_get_serial_port_data(port);
	unsigned long flags = 0;

	dev_dbg(tty->dev, "%s\n", __func__);

	spin_lock_irqsave(&metro_priv->lock, flags);
	control_state = metro_priv->control_state;
	spin_unlock_irqrestore(&metro_priv->lock, flags);

	return control_state;
	}

	static int metrousb_tiocmset(struct tty_struct *tty,
	unsigned int set, unsigned int clear)
	{
	struct usb_serial_port *port = tty->driver_data;
	struct usb_serial *serial = port->serial;
	struct metrousb_private *metro_priv = usb_get_serial_port_data(port);
	unsigned long flags = 0;
	unsigned long control_state = 0;

	dev_dbg(tty->dev, "%s - set=%d, clear=%d\n", __func__, set, clear);

	spin_lock_irqsave(&metro_priv->lock, flags);
	control_state = metro_priv->control_state;

	/* Set the RTS and DTR values. */
	if (set & TIOCM_RTS)
	control_state \|= TIOCM_RTS;
	if (set & TIOCM_DTR)
	control_state \|= TIOCM_DTR;
	if (clear & TIOCM_RTS)
	control_state &= ~TIOCM_RTS;
	if (clear & TIOCM_DTR)
	control_state &= ~TIOCM_DTR;

	metro_priv->control_state = control_state;
	spin_unlock_irqrestore(&metro_priv->lock, flags);
	return metrousb_set_modem_ctrl(serial, control_state);
	}

	static void metrousb_unthrottle(struct tty_struct *tty)
	{
	struct usb_serial_port *port = tty->driver_data;
	struct metrousb_private *metro_priv = usb_get_serial_port_data(port);
	unsigned long flags = 0;
	int result = 0;

	dev_dbg(tty->dev, "%s\n", __func__);

	/* Set the private information for the port to resume reading data. */
	spin_lock_irqsave(&metro_priv->lock, flags);
	metro_priv->throttled = 0;
	spin_unlock_irqrestore(&metro_priv->lock, flags);

	/* Submit the urb to read from the port. */
	port->interrupt_in_urb->dev = port->serial->dev;
	result = usb_submit_urb(port->interrupt_in_urb, GFP_ATOMIC);
	if (result)
	dev_err(tty->dev,
	"failed submitting interrupt in urb error code=%d\n",
	result);
	}

	static struct usb_serial_driver metrousb_device = {
	.driver = {
	.owner = THIS_MODULE,
	.name = "metro-usb",
	},
	.description = "Metrologic USB to Serial",
	.id_table = id_table,
	.num_ports = 1,
	.open = metrousb_open,
	.close = metrousb_cleanup,
	.read_int_callback = metrousb_read_int_callback,
	.write_int_callback = metrousb_write_int_callback,
	.attach = metrousb_startup,
	.release = metrousb_shutdown,
	.throttle = metrousb_throttle,
	.unthrottle = metrousb_unthrottle,
	.tiocmget = metrousb_tiocmget,
	.tiocmset = metrousb_tiocmset,
	};

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

	module_usb_serial_driver(serial_drivers, id_table);

	MODULE_LICENSE("GPL");
	MODULE_AUTHOR("Philip Nicastro");
	MODULE_AUTHOR("Aleksey Babahin <tamerlan311@gmail.com>");
	MODULE_DESCRIPTION(DRIVER_DESC);

	/* Module input parameters */
	module_param(debug, bool, S_IRUGO \| S_IWUSR);
	MODULE_PARM_DESC(debug, "Print debug info (bool 1=on, 0=off)");