/*
 * Opticon USB barcode to serial driver
 *
 * Copyright (C) 2011 Martin Jansen <martin.jansen@opticon.com>
 * 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/slab.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>

#define CONTROL_RTS			0x02
#define RESEND_CTS_STATE	0x03

/* max number of write urbs in flight */
#define URB_UPPER_LIMIT	8

/* This driver works for the Opticon 1D barcode reader
 * an examples of 1D barcode types are EAN, UPC, Code39, IATA etc.. */
#define DRIVER_DESC	"Opticon USB barcode to serial driver (1D)"

static bool debug;

static const 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;
	bool cts;
	int outstanding_urbs;
};



static void opticon_read_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 data_length;
	unsigned long flags;

	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 CTS level change, the third byte is the CTS
		 *	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) {
				tty_insert_flip_string(tty, data + 2,
						       data_length);
				tty_flip_buffer_push(tty);
				tty_kref_put(tty);
			}
		} else {
			if ((data[0] == 0x00) && (data[1] == 0x01)) {
				spin_lock_irqsave(&priv->lock, flags);
				/* CTS status information package */
				if (data[2] == 0x00)
					priv->cts = false;
				else
					priv->cts = true;
				spin_unlock_irqrestore(&priv->lock, flags);
			} else {
				dev_dbg(&priv->udev->dev,
					"Unknown data packet received from the device:"
					" %2x %2x\n",
					data[0], data[1]);
			}
		}
	} else {
		dev_dbg(&priv->udev->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) {
		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_read_bulk_callback, priv);
		result = usb_submit_urb(priv->bulk_read_urb, GFP_ATOMIC);
		if (result)
			dev_err(&port->dev,
			    "%s - failed resubmitting read urb, error %d\n",
							__func__, result);
	} else
		priv->actually_throttled = true;
	spin_unlock(&priv->lock);
}

static int send_control_msg(struct usb_serial_port *port, u8 requesttype,
				u8 val)
{
	struct usb_serial *serial = port->serial;
	int retval;
	u8 buffer[2];

	buffer[0] = val;
	/* Send the message to the vendor control endpoint
	 * of the connected device */
	retval = usb_control_msg(serial->dev, usb_sndctrlpipe(serial->dev, 0),
				requesttype,
				USB_DIR_OUT|USB_TYPE_VENDOR|USB_RECIP_INTERFACE,
				0, 0, buffer, 1, 0);

	return retval;
}

static int opticon_open(struct tty_struct *tty, struct usb_serial_port *port)
{
	struct opticon_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;
	priv->port = port;
	priv->rts = false;
	spin_unlock_irqrestore(&priv->lock, flags);

	/* Clear RTS line */
	send_control_msg(port, CONTROL_RTS, 0);

	/* Setup the read URB and start reading from the device */