/*
   * Symbol USB barcode to serial driver
   *
   * Copyright (C) 2013 Johan Hovold <jhovold@gmail.com>
   * Copyright (C) 2009 Greg Kroah-Hartman <gregkh@suse.de>
   * Copyright (C) 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/tty.h>
  #include <linux/slab.h>
  #include <linux/tty_driver.h>
  #include <linux/tty_flip.h>
  #include <linux/module.h>
  #include <linux/usb.h>
  #include <linux/usb/serial.h>
  #include <linux/uaccess.h>
  
  static const struct usb_device_id id_table[] = {
  	{ USB_DEVICE(0x05e0, 0x0600) },
  	{ },
  };
  MODULE_DEVICE_TABLE(usb, id_table);
  
  struct symbol_private {
  	spinlock_t lock;	/* protects the following flags */
  	bool throttled;
  	bool actually_throttled;
  };
  
  static void symbol_int_callback(struct urb *urb)
  {
  	struct usb_serial_port *port = urb->context;
  	struct symbol_private *priv = usb_get_serial_port_data(port);
  	unsigned char *data = urb->transfer_buffer;
  	int status = urb->status;
  	int result;
  	int data_length;
  
  	switch (status) {
  	case 0:
  		/* success */
  		break;
  	case -ECONNRESET:
  	case -ENOENT:
  	case -ESHUTDOWN:
  		/* this urb is terminated, clean up */
  		dev_dbg(&port->dev, "%s - urb shutting down with status: %d
  ",
  			__func__, status);
  		return;
  	default:
  		dev_dbg(&port->dev, "%s - nonzero urb status received: %d
  ",
  			__func__, status);
  		goto exit;
  	}
  
  	usb_serial_debug_data(&port->dev, __func__, urb->actual_length, data);
  
  	if (urb->actual_length > 1) {
  		data_length = urb->actual_length - 1;
  
  		/*
  		 * Data from the device comes with a 1 byte header:
  		 *
  		 * <size of data>data...
  		 * 	This is real data to be sent to the tty layer
  		 * we pretty much just ignore the size and send everything
  		 * else to the tty layer.
  		 */
  		tty_insert_flip_string(&port->port, &data[1], data_length);
  		tty_flip_buffer_push(&port->port);
  	} else {
  		dev_dbg(&port->dev,
  			"Improper amount 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) {
  		result = usb_submit_urb(port->interrupt_in_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 symbol_open(struct tty_struct *tty, struct usb_serial_port *port)
  {
  	struct symbol_private *priv = usb_get_serial_data(port->serial);
  	unsigned long flags;
  	int result = 0;
  
  	spin_lock_irqsave(&priv->lock, flags);
  	priv->throttled = false;
  	priv->actually_throttled = false;
  	spin_unlock_irqrestore(&priv->lock, flags);
  
  	/* Start reading from the device */
  	result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
  	if (result)
  		dev_err(&port->dev,
  			"%s - failed resubmitting read urb, error %d
  ",
  			__func__, result);
  	return result;
  }
  
  static void symbol_close(struct usb_serial_port *port)
  {
  	usb_kill_urb(port->interrupt_in_urb);
  }
  
  static void symbol_throttle(struct tty_struct *tty)
  {
  	struct usb_serial_port *port = tty->driver_data;
  	struct symbol_private *priv = usb_get_serial_data(port->serial);
  
  	spin_lock_irq(&priv->lock);
  	priv->throttled = true;
  	spin_unlock_irq(&priv->lock);
  }
  
  static void symbol_unthrottle(struct tty_struct *tty)
  {
  	struct usb_serial_port *port = tty->driver_data;
  	struct symbol_private *priv = usb_get_serial_data(port->serial);
  	int result;
  	bool was_throttled;
  
  	spin_lock_irq(&priv->lock);
  	priv->throttled = false;
  	was_throttled = priv->actually_throttled;
  	priv->actually_throttled = false;
  	spin_unlock_irq(&priv->lock);
  
  	if (was_throttled) {
  		result = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
  		if (result)
  			dev_err(&port->dev,
  				"%s - failed submitting read urb, error %d
  ",
  							__func__, result);
  	}
  }
  
  static int symbol_startup(struct usb_serial *serial)
  {
  	if (!serial->num_interrupt_in) {
  		dev_err(&serial->dev->dev, "no interrupt-in endpoint
  ");
  		return -ENODEV;
  	}
  
  	return 0;
  }
  
  static int symbol_port_probe(struct usb_serial_port *port)
  {
  	struct symbol_private *priv;
  
  	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
  	if (!priv)
  		return -ENOMEM;
  
  	spin_lock_init(&priv->lock);
  
  	usb_set_serial_port_data(port, priv);
  
  	return 0;
  }
  
  static int symbol_port_remove(struct usb_serial_port *port)
  {
  	struct symbol_private *priv = usb_get_serial_port_data(port);
  
  	kfree(priv);
  
  	return 0;
  }
  
  static struct usb_serial_driver symbol_device = {
  	.driver = {
  		.owner =	THIS_MODULE,
  		.name =		"symbol",
  	},
  	.id_table =		id_table,
  	.num_ports =		1,
  	.attach =		symbol_startup,
  	.port_probe =		symbol_port_probe,
  	.port_remove =		symbol_port_remove,
  	.open =			symbol_open,
  	.close =		symbol_close,
  	.throttle = 		symbol_throttle,
  	.unthrottle =		symbol_unthrottle,
  	.read_int_callback =	symbol_int_callback,
  };
  
  static struct usb_serial_driver * const serial_drivers[] = {
  	&symbol_device, NULL
  };
  
  module_usb_serial_driver(serial_drivers, id_table);
  
  MODULE_LICENSE("GPL");