/*
    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/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>
  
  #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 const 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);
  
  /* UNI-Directional mode commands for device configure */
  #define UNI_CMD_OPEN	0x80
  #define UNI_CMD_CLOSE	0xFF
  
  static 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);
  	unsigned char *data = urb->transfer_buffer;
  	int throttled = 0;
  	int result = 0;
  	unsigned long flags = 0;
  
  	dev_dbg(&port->dev, "%s
  ", __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
  ",
  			__func__, urb->status);
  		return;
  	default:
  		dev_dbg(&port->dev,
  			"%s - non-zero urb received, error code=%d
  ",
  			__func__, urb->status);
  		goto exit;
  	}
  
  
  	/* Set the data read from the usb port into the serial port buffer. */
  	if (urb->actual_length) {
  		/* Loop through the data copying each byte to the tty layer. */
  		tty_insert_flip_string(&port->port, data, urb->actual_length);
  
  		/* Force the data to the tty layer. */
  		tty_flip_buffer_push(&port->port);
  	}
  
  	/* 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
  ",
  				__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
  ",
  			__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.
  ",
  		__func__);
  }
  
  static void metrousb_cleanup(struct usb_serial_port *port)
  {
  	dev_dbg(&port->dev, "%s
  ", __func__);
  
  	usb_unlink_urb(port->interrupt_in_urb);
  	usb_kill_urb(port->interrupt_in_urb);
  
  	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
  ", __func__);
  
  	/* Make sure the urb is initialized. */
  	if (!port->interrupt_in_urb) {
  		dev_err(&port->dev, "%s - interrupt urb not initialized
  ",
  			__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);
  
  	/* 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
  ",
  			__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, error code=%d
  ",
  			__func__, result);
  		goto exit;
  	}
  
  	dev_dbg(&port->dev, "%s - port open
  ", __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
  ",
  		__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
  ",
  			__func__, mcr, retval);
  
  	return retval;
  }
  
  static int metrousb_port_probe(struct usb_serial_port *port)
  {
  	struct metrousb_private *metro_priv;
  
  	metro_priv = kzalloc(sizeof(*metro_priv), GFP_KERNEL);
  	if (!metro_priv)
  		return -ENOMEM;
  
  	spin_lock_init(&metro_priv->lock);
  
  	usb_set_serial_port_data(port, metro_priv);
  
  	return 0;
  }
  
  static int metrousb_port_remove(struct usb_serial_port *port)
  {
  	struct metrousb_private *metro_priv;
  
  	metro_priv = usb_get_serial_port_data(port);
  	kfree(metro_priv);
  
  	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
  ", __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
  ", __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
  ", __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
  ", __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
  ",
  			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,
  	.port_probe		= metrousb_port_probe,
  	.port_remove		= metrousb_port_remove,
  	.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);