/*
   * Opticon USB barcode to serial driver
   *

   * Copyright (C) 2008 - 2009 Greg Kroah-Hartman <gregkh@suse.de>
   * Copyright (C) 2008 - 2009 Novell Inc.

   *
   *	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.
   */
  
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/tty.h>
  #include <linux/tty_driver.h>
  #include <linux/tty_flip.h>

  #include <linux/serial.h>

  #include <linux/module.h>
  #include <linux/usb.h>
  #include <linux/usb/serial.h>
  #include <linux/uaccess.h>
  
  static int debug;
  
  static struct usb_device_id id_table[] = {
  	{ USB_DEVICE(0x065a, 0x0009) },
  	{ },
  };
  MODULE_DEVICE_TABLE(usb, id_table);
  
  /* This structure holds all of the individual device information */
  struct opticon_private {
  	struct usb_device *udev;
  	struct usb_serial *serial;
  	struct usb_serial_port *port;
  	unsigned char *bulk_in_buffer;
  	struct urb *bulk_read_urb;
  	int buffer_size;
  	u8 bulk_address;
  	spinlock_t lock;	/* protects the following flags */
  	bool throttled;
  	bool actually_throttled;
  	bool rts;

  	int outstanding_urbs;

  };

  /* max number of write urbs in flight */
  #define URB_UPPER_LIMIT	4

  static void opticon_bulk_callback(struct urb *urb)
  {
  	struct opticon_private *priv = urb->context;
  	unsigned char *data = urb->transfer_buffer;
  	struct usb_serial_port *port = priv->port;
  	int status = urb->status;
  	struct tty_struct *tty;
  	int result;
  	int available_room = 0;
  	int data_length;
  
  	dbg("%s - port %d", __func__, port->number);
  
  	switch (status) {
  	case 0:
  		/* success */
  		break;
  	case -ECONNRESET:
  	case -ENOENT:
  	case -ESHUTDOWN:
  		/* this urb is terminated, clean up */
  		dbg("%s - urb shutting down with status: %d",
  		    __func__, status);
  		return;
  	default:
  		dbg("%s - nonzero urb status received: %d",
  		    __func__, status);
  		goto exit;
  	}
  
  	usb_serial_debug_data(debug, &port->dev, __func__, urb->actual_length,
  			      data);
  
  	if (urb->actual_length > 2) {
  		data_length = urb->actual_length - 2;
  
  		/*
  		 * Data from the device comes with a 2 byte header:
  		 *
  		 * <0x00><0x00>data...
  		 * 	This is real data to be sent to the tty layer
  		 * <0x00><0x01)level
  		 * 	This is a RTS level change, the third byte is the RTS
  		 * 	value (0 for low, 1 for high).
  		 */
  		if ((data[0] == 0x00) && (data[1] == 0x00)) {
  			/* real data, send it to the tty layer */
  			tty = tty_port_tty_get(&port->port);
  			if (tty) {
  				available_room = tty_buffer_request_room(tty,
  								data_length);
  				if (available_room) {
  					tty_insert_flip_string(tty, data,
  							       available_room);
  					tty_flip_buffer_push(tty);
  				}
  				tty_kref_put(tty);
  			}
  		} else {
  			if ((data[0] == 0x00) && (data[1] == 0x01)) {
  				if (data[2] == 0x00)
  					priv->rts = false;
  				else
  					priv->rts = true;

  			} else {
  			dev_dbg(&priv->udev->dev,
  				"Unknown data packet received from the device:"
  				" %2x %2x
  ",
  				data[0], data[1]);
  			}
  		}
  	} else {
  		dev_dbg(&priv->udev->dev,
  			"Improper ammount of data received from the device, "
  			"%d bytes", urb->actual_length);
  	}
  
  exit:
  	spin_lock(&priv->lock);
  
  	/* Continue trying to always read if we should */
  	if (!priv->throttled) {
  		usb_fill_bulk_urb(priv->bulk_read_urb, priv->udev,
  				  usb_rcvbulkpipe(priv->udev,
  						  priv->bulk_address),
  				  priv->bulk_in_buffer, priv->buffer_size,
  				  opticon_bulk_callback, priv);
  		result = usb_submit_urb(port->read_urb, GFP_ATOMIC);
  		if (result)
  			dev_err(&port->dev,
  			    "%s - failed resubmitting read urb, error %d
  ",
  							__func__, result);
  	} else
  		priv->actually_throttled = true;
  	spin_unlock(&priv->lock);
  }
  
  static int opticon_open(struct tty_struct *tty, struct usb_serial_port *port,
  			struct file *filp)
  {
  	struct opticon_private *priv = usb_get_serial_data(port->serial);
  	unsigned long flags;
  	int result = 0;
  
  	dbg("%s - port %d", __func__, port->number);
  
  	spin_lock_irqsave(&priv->lock, flags);
  	priv->throttled = false;
  	priv->actually_throttled = false;
  	priv->port = port;
  	spin_unlock_irqrestore(&priv->lock, flags);

  	/* Start reading from the device */
  	usb_fill_bulk_urb(priv->bulk_read_urb, priv->udev,
  			  usb_rcvbulkpipe(priv->udev,
  					  priv->bulk_address),
  			  priv->bulk_in_buffer, priv->buffer_size,
  			  opticon_bulk_callback, priv);
  	result = usb_submit_urb(priv->bulk_read_urb, GFP_KERNEL);
  	if (result)
  		dev_err(&port->dev,
  			"%s - failed resubmitting read urb, error %d
  ",
  			__func__, result);
  	return result;
  }

  static void opticon_close(struct usb_serial_port *port)

  {
  	struct opticon_private *priv = usb_get_serial_data(port->serial);
  
  	dbg("%s - port %d", __func__, port->number);
  
  	/* shutdown our urbs */
  	usb_kill_urb(priv->bulk_read_urb);
  }

  static void opticon_write_bulk_callback(struct urb *urb)
  {
  	struct opticon_private *priv = urb->context;
  	int status = urb->status;
  	unsigned long flags;
  
  	/* free up the transfer buffer, as usb_free_urb() does not do this */
  	kfree(urb->transfer_buffer);
  
  	if (status)
  		dbg("%s - nonzero write bulk status received: %d",
  		    __func__, status);
  
  	spin_lock_irqsave(&priv->lock, flags);
  	--priv->outstanding_urbs;
  	spin_unlock_irqrestore(&priv->lock, flags);
  
  	usb_serial_port_softint(priv->port);
  }
  
  static int opticon_write(struct tty_struct *tty, struct usb_serial_port *port,
  			 const unsigned char *buf, int count)
  {
  	struct opticon_private *priv = usb_get_serial_data(port->serial);
  	struct usb_serial *serial = port->serial;
  	struct urb *urb;
  	unsigned char *buffer;
  	unsigned long flags;
  	int status;
  
  	dbg("%s - port %d", __func__, port->number);
  
  	spin_lock_irqsave(&priv->lock, flags);
  	if (priv->outstanding_urbs > URB_UPPER_LIMIT) {
  		spin_unlock_irqrestore(&priv->lock, flags);
  		dbg("%s - write limit hit
  ", __func__);
  		return 0;
  	}
  	priv->outstanding_urbs++;
  	spin_unlock_irqrestore(&priv->lock, flags);
  
  	buffer = kmalloc(count, GFP_ATOMIC);
  	if (!buffer) {
  		dev_err(&port->dev, "out of memory
  ");
  		count = -ENOMEM;
  		goto error_no_buffer;
  	}
  
  	urb = usb_alloc_urb(0, GFP_ATOMIC);
  	if (!urb) {
  		dev_err(&port->dev, "no more free urbs
  ");
  		count = -ENOMEM;
  		goto error_no_urb;
  	}
  
  	memcpy(buffer, buf, count);
  
  	usb_serial_debug_data(debug, &port->dev, __func__, count, buffer);
  
  	usb_fill_bulk_urb(urb, serial->dev,
  			  usb_sndbulkpipe(serial->dev,
  					  port->bulk_out_endpointAddress),
  			  buffer, count, opticon_write_bulk_callback, priv);
  
  	/* send it down the pipe */
  	status = usb_submit_urb(urb, GFP_ATOMIC);
  	if (status) {
  		dev_err(&port->dev,
  		   "%s - usb_submit_urb(write bulk) failed with status = %d
  ",
  							__func__, status);
  		count = status;
  		goto error;
  	}
  
  	/* we are done with this urb, so let the host driver
  	 * really free it when it is finished with it */
  	usb_free_urb(urb);
  
  	return count;
  error:
  	usb_free_urb(urb);
  error_no_urb:
  	kfree(buffer);
  error_no_buffer:
  	spin_lock_irqsave(&priv->lock, flags);
  	--priv->outstanding_urbs;
  	spin_unlock_irqrestore(&priv->lock, flags);
  	return count;
  }
  
  static int opticon_write_room(struct tty_struct *tty)
  {
  	struct usb_serial_port *port = tty->driver_data;
  	struct opticon_private *priv = usb_get_serial_data(port->serial);
  	unsigned long flags;
  
  	dbg("%s - port %d", __func__, port->number);
  
  	/*
  	 * We really can take almost anything the user throws at us
  	 * but let's pick a nice big number to tell the tty
  	 * layer that we have lots of free space, unless we don't.
  	 */
  	spin_lock_irqsave(&priv->lock, flags);
  	if (priv->outstanding_urbs > URB_UPPER_LIMIT * 2 / 3) {
  		spin_unlock_irqrestore(&priv->lock, flags);
  		dbg("%s - write limit hit
  ", __func__);
  		return 0;
  	}
  	spin_unlock_irqrestore(&priv->lock, flags);
  
  	return 2048;
  }

  static void opticon_throttle(struct tty_struct *tty)
  {
  	struct usb_serial_port *port = tty->driver_data;
  	struct opticon_private *priv = usb_get_serial_data(port->serial);
  	unsigned long flags;
  
  	dbg("%s - port %d", __func__, port->number);
  	spin_lock_irqsave(&priv->lock, flags);
  	priv->throttled = true;
  	spin_unlock_irqrestore(&priv->lock, flags);
  }
  
  
  static void opticon_unthrottle(struct tty_struct *tty)
  {
  	struct usb_serial_port *port = tty->driver_data;
  	struct opticon_private *priv = usb_get_serial_data(port->serial);
  	unsigned long flags;
  	int result;
  
  	dbg("%s - port %d", __func__, port->number);
  
  	spin_lock_irqsave(&priv->lock, flags);
  	priv->throttled = false;
  	priv->actually_throttled = false;
  	spin_unlock_irqrestore(&priv->lock, flags);
  
  	priv->bulk_read_urb->dev = port->serial->dev;
  	result = usb_submit_urb(priv->bulk_read_urb, GFP_ATOMIC);
  	if (result)
  		dev_err(&port->dev,
  			"%s - failed submitting read urb, error %d
  ",
  							__func__, result);
  }

  static int opticon_tiocmget(struct tty_struct *tty, struct file *file)
  {
  	struct usb_serial_port *port = tty->driver_data;
  	struct opticon_private *priv = usb_get_serial_data(port->serial);
  	unsigned long flags;
  	int result = 0;
  
  	dbg("%s - port %d", __func__, port->number);
  
  	spin_lock_irqsave(&priv->lock, flags);
  	if (priv->rts)
  		result = TIOCM_RTS;
  	spin_unlock_irqrestore(&priv->lock, flags);
  
  	dbg("%s - %x", __func__, result);
  	return result;
  }
  
  static int get_serial_info(struct opticon_private *priv,
  			   struct serial_struct __user *serial)
  {
  	struct serial_struct tmp;
  
  	if (!serial)
  		return -EFAULT;
  
  	memset(&tmp, 0x00, sizeof(tmp));
  
  	/* fake emulate a 16550 uart to make userspace code happy */
  	tmp.type		= PORT_16550A;
  	tmp.line		= priv->serial->minor;
  	tmp.port		= 0;
  	tmp.irq			= 0;
  	tmp.flags		= ASYNC_SKIP_TEST | ASYNC_AUTO_IRQ;
  	tmp.xmit_fifo_size	= 1024;
  	tmp.baud_base		= 9600;
  	tmp.close_delay		= 5*HZ;
  	tmp.closing_wait	= 30*HZ;
  
  	if (copy_to_user(serial, &tmp, sizeof(*serial)))
  		return -EFAULT;
  	return 0;
  }
  
  static int opticon_ioctl(struct tty_struct *tty, struct file *file,
  			 unsigned int cmd, unsigned long arg)
  {
  	struct usb_serial_port *port = tty->driver_data;
  	struct opticon_private *priv = usb_get_serial_data(port->serial);
  
  	dbg("%s - port %d, cmd = 0x%x", __func__, port->number, cmd);
  
  	switch (cmd) {
  	case TIOCGSERIAL:
  		return get_serial_info(priv,
  				       (struct serial_struct __user *)arg);
  	}
  
  	return -ENOIOCTLCMD;
  }

  static int opticon_startup(struct usb_serial *serial)
  {
  	struct opticon_private *priv;
  	struct usb_host_interface *intf;
  	int i;
  	int retval = -ENOMEM;
  	bool bulk_in_found = false;
  
  	/* create our private serial structure */
  	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
  	if (priv == NULL) {
  		dev_err(&serial->dev->dev, "%s - Out of memory
  ", __func__);
  		return -ENOMEM;
  	}
  	spin_lock_init(&priv->lock);
  	priv->serial = serial;
  	priv->port = serial->port[0];
  	priv->udev = serial->dev;
  
  	/* find our bulk endpoint */
  	intf = serial->interface->altsetting;
  	for (i = 0; i < intf->desc.bNumEndpoints; ++i) {
  		struct usb_endpoint_descriptor *endpoint;
  
  		endpoint = &intf->endpoint[i].desc;
  		if (!usb_endpoint_is_bulk_in(endpoint))
  			continue;
  
  		priv->bulk_read_urb = usb_alloc_urb(0, GFP_KERNEL);
  		if (!priv->bulk_read_urb) {
  			dev_err(&priv->udev->dev, "out of memory
  ");
  			goto error;
  		}
  
  		priv->buffer_size = le16_to_cpu(endpoint->wMaxPacketSize) * 2;
  		priv->bulk_in_buffer = kmalloc(priv->buffer_size, GFP_KERNEL);
  		if (!priv->bulk_in_buffer) {
  			dev_err(&priv->udev->dev, "out of memory
  ");
  			goto error;
  		}
  
  		priv->bulk_address = endpoint->bEndpointAddress;
  
  		/* set up our bulk urb */
  		usb_fill_bulk_urb(priv->bulk_read_urb, priv->udev,
  				  usb_rcvbulkpipe(priv->udev,
  						  endpoint->bEndpointAddress),
  				  priv->bulk_in_buffer, priv->buffer_size,
  				  opticon_bulk_callback, priv);
  
  		bulk_in_found = true;
  		break;
  		}
  
  	if (!bulk_in_found) {
  		dev_err(&priv->udev->dev,
  			"Error - the proper endpoints were not found!
  ");
  		goto error;
  	}
  
  	usb_set_serial_data(serial, priv);
  	return 0;
  
  error:
  	usb_free_urb(priv->bulk_read_urb);
  	kfree(priv->bulk_in_buffer);
  	kfree(priv);
  	return retval;
  }

  static void opticon_disconnect(struct usb_serial *serial)

  {
  	struct opticon_private *priv = usb_get_serial_data(serial);
  
  	dbg("%s", __func__);
  
  	usb_kill_urb(priv->bulk_read_urb);
  	usb_free_urb(priv->bulk_read_urb);

  }
  
  static void opticon_release(struct usb_serial *serial)
  {
  	struct opticon_private *priv = usb_get_serial_data(serial);
  
  	dbg("%s", __func__);

  	kfree(priv->bulk_in_buffer);
  	kfree(priv);

  }

  static int opticon_suspend(struct usb_interface *intf, pm_message_t message)
  {
  	struct usb_serial *serial = usb_get_intfdata(intf);
  	struct opticon_private *priv = usb_get_serial_data(serial);
  
  	usb_kill_urb(priv->bulk_read_urb);
  	return 0;
  }
  
  static int opticon_resume(struct usb_interface *intf)
  {
  	struct usb_serial *serial = usb_get_intfdata(intf);
  	struct opticon_private *priv = usb_get_serial_data(serial);
  	struct usb_serial_port *port = serial->port[0];
  	int result;
  
  	mutex_lock(&port->mutex);
  	if (port->port.count)
  		result = usb_submit_urb(priv->bulk_read_urb, GFP_NOIO);
  	else
  		result = 0;
  	mutex_unlock(&port->mutex);
  	return result;
  }

  
  static struct usb_driver opticon_driver = {
  	.name =		"opticon",
  	.probe =	usb_serial_probe,
  	.disconnect =	usb_serial_disconnect,

  	.suspend =	opticon_suspend,
  	.resume =	opticon_resume,

  	.id_table =	id_table,
  	.no_dynamic_id = 	1,
  };
  
  static struct usb_serial_driver opticon_device = {
  	.driver = {
  		.owner =	THIS_MODULE,
  		.name =		"opticon",
  	},
  	.id_table =		id_table,
  	.usb_driver = 		&opticon_driver,
  	.num_ports =		1,
  	.attach =		opticon_startup,
  	.open =			opticon_open,
  	.close =		opticon_close,

  	.write =		opticon_write,
  	.write_room = 		opticon_write_room,

  	.disconnect =		opticon_disconnect,
  	.release =		opticon_release,

  	.throttle = 		opticon_throttle,
  	.unthrottle =		opticon_unthrottle,

  	.ioctl =		opticon_ioctl,
  	.tiocmget =		opticon_tiocmget,

  };
  
  static int __init opticon_init(void)
  {
  	int retval;
  
  	retval = usb_serial_register(&opticon_device);
  	if (retval)
  		return retval;
  	retval = usb_register(&opticon_driver);
  	if (retval)
  		usb_serial_deregister(&opticon_device);
  	return retval;
  }
  
  static void __exit opticon_exit(void)
  {
  	usb_deregister(&opticon_driver);
  	usb_serial_deregister(&opticon_device);
  }
  
  module_init(opticon_init);
  module_exit(opticon_exit);
  MODULE_LICENSE("GPL");
  
  module_param(debug, bool, S_IRUGO | S_IWUSR);
  MODULE_PARM_DESC(debug, "Debug enabled or not");