/*
   * Opticon USB barcode to serial driver
   *
   * Copyright (C) 2011 - 2012 Johan Hovold <jhovold@gmail.com>
   * 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/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 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 {
  	spinlock_t lock;	/* protects the following flags */
  	bool rts;
  	bool cts;
  	int outstanding_urbs;
  };
  
  
  static void opticon_process_data_packet(struct usb_serial_port *port,
  					const unsigned char *buf, size_t len)
  {
  	tty_insert_flip_string(&port->port, buf, len);
  	tty_flip_buffer_push(&port->port);
  }
  
  static void opticon_process_status_packet(struct usb_serial_port *port,
  					const unsigned char *buf, size_t len)
  {
  	struct opticon_private *priv = usb_get_serial_port_data(port);
  	unsigned long flags;
  
  	spin_lock_irqsave(&priv->lock, flags);
  	if (buf[0] == 0x00)
  		priv->cts = false;
  	else
  		priv->cts = true;
  	spin_unlock_irqrestore(&priv->lock, flags);
  }
  
  static void opticon_process_read_urb(struct urb *urb)
  {
  	struct usb_serial_port *port = urb->context;
  	const unsigned char *hdr = urb->transfer_buffer;
  	const unsigned char *data = hdr + 2;
  	size_t data_len = urb->actual_length - 2;
  
  	if (urb->actual_length <= 2) {
  		dev_dbg(&port->dev, "malformed packet received: %d bytes
  ",
  							urb->actual_length);
  		return;
  	}
  	/*
  	 * 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 ((hdr[0] == 0x00) && (hdr[1] == 0x00)) {
  		opticon_process_data_packet(port, data, data_len);
  	} else if ((hdr[0] == 0x00) && (hdr[1] == 0x01)) {
  		opticon_process_status_packet(port, data, data_len);
  	} else {
  		dev_dbg(&port->dev, "unknown packet received: %02x %02x
  ",
  							hdr[0], hdr[1]);
  	}
  }
  
  static int send_control_msg(struct usb_serial_port *port, u8 requesttype,
  				u8 val)
  {
  	struct usb_serial *serial = port->serial;
  	int retval;
  	u8 *buffer;
  
  	buffer = kzalloc(1, GFP_KERNEL);
  	if (!buffer)
  		return -ENOMEM;
  
  	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);
  	kfree(buffer);
  
  	if (retval < 0)
  		return retval;
  
  	return 0;
  }
  
  static int opticon_open(struct tty_struct *tty, struct usb_serial_port *port)
  {
  	struct opticon_private *priv = usb_get_serial_port_data(port);
  	unsigned long flags;
  	int res;
  
  	spin_lock_irqsave(&priv->lock, flags);
  	priv->rts = false;
  	spin_unlock_irqrestore(&priv->lock, flags);
  
  	/* Clear RTS line */
  	send_control_msg(port, CONTROL_RTS, 0);
  
  	/* clear the halt status of the endpoint */
  	usb_clear_halt(port->serial->dev, port->read_urb->pipe);
  
  	res = usb_serial_generic_open(tty, port);
  	if (!res)
  		return res;
  
  	/* Request CTS line state, sometimes during opening the current
  	 * CTS state can be missed. */
  	send_control_msg(port, RESEND_CTS_STATE, 1);
  
  	return res;
  }
  
  static void opticon_write_control_callback(struct urb *urb)
  {
  	struct usb_serial_port *port = urb->context;
  	struct opticon_private *priv = usb_get_serial_port_data(port);
  	int status = urb->status;
  	unsigned long flags;
  
  	/* free up the transfer buffer, as usb_free_urb() does not do this */
  	kfree(urb->transfer_buffer);
  
  	/* setup packet may be set if we're using it for writing */
  	kfree(urb->setup_packet);
  
  	if (status)
  		dev_dbg(&port->dev,
  			"%s - non-zero urb status received: %d
  ",
  			__func__, status);
  
  	spin_lock_irqsave(&priv->lock, flags);
  	--priv->outstanding_urbs;
  	spin_unlock_irqrestore(&priv->lock, flags);
  
  	usb_serial_port_softint(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_port_data(port);
  	struct usb_serial *serial = port->serial;
  	struct urb *urb;
  	unsigned char *buffer;
  	unsigned long flags;
  	int status;
  	struct usb_ctrlrequest *dr;
  
  	spin_lock_irqsave(&priv->lock, flags);
  	if (priv->outstanding_urbs > URB_UPPER_LIMIT) {
  		spin_unlock_irqrestore(&priv->lock, flags);
  		dev_dbg(&port->dev, "%s - write limit hit
  ", __func__);
  		return 0;
  	}
  	priv->outstanding_urbs++;
  	spin_unlock_irqrestore(&priv->lock, flags);
  
  	buffer = kmalloc(count, GFP_ATOMIC);
  	if (!buffer) {
  		count = -ENOMEM;
  		goto error_no_buffer;
  	}
  
  	urb = usb_alloc_urb(0, GFP_ATOMIC);
  	if (!urb) {
  		count = -ENOMEM;
  		goto error_no_urb;
  	}
  
  	memcpy(buffer, buf, count);
  
  	usb_serial_debug_data(&port->dev, __func__, count, buffer);
  
  	/* The connected devices do not have a bulk write endpoint,
  	 * to transmit data to de barcode device the control endpoint is used */
  	dr = kmalloc(sizeof(struct usb_ctrlrequest), GFP_ATOMIC);
  	if (!dr) {
  		count = -ENOMEM;
  		goto error_no_dr;
  	}
  
  	dr->bRequestType = USB_TYPE_VENDOR | USB_RECIP_INTERFACE | USB_DIR_OUT;
  	dr->bRequest = 0x01;
  	dr->wValue = 0;
  	dr->wIndex = 0;
  	dr->wLength = cpu_to_le16(count);
  
  	usb_fill_control_urb(urb, serial->dev,
  		usb_sndctrlpipe(serial->dev, 0),
  		(unsigned char *)dr, buffer, count,
  		opticon_write_control_callback, port);
  
  	/* send it down the pipe */
  	status = usb_submit_urb(urb, GFP_ATOMIC);
  	if (status) {
  		dev_err(&port->dev,
  		"%s - usb_submit_urb(write endpoint) failed 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:
  	kfree(dr);
  error_no_dr:
  	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_port_data(port);
  	unsigned long flags;
  
  	/*
  	 * 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);
  		dev_dbg(&port->dev, "%s - write limit hit
  ", __func__);
  		return 0;
  	}
  	spin_unlock_irqrestore(&priv->lock, flags);
  
  	return 2048;
  }
  
  static int opticon_tiocmget(struct tty_struct *tty)
  {
  	struct usb_serial_port *port = tty->driver_data;
  	struct opticon_private *priv = usb_get_serial_port_data(port);
  	unsigned long flags;
  	int result = 0;
  
  	spin_lock_irqsave(&priv->lock, flags);
  	if (priv->rts)
  		result |= TIOCM_RTS;
  	if (priv->cts)
  		result |= TIOCM_CTS;
  	spin_unlock_irqrestore(&priv->lock, flags);
  
  	dev_dbg(&port->dev, "%s - %x
  ", __func__, result);
  	return result;
  }
  
  static int opticon_tiocmset(struct tty_struct *tty,
  			   unsigned int set, unsigned int clear)
  {
  	struct usb_serial_port *port = tty->driver_data;
  	struct opticon_private *priv = usb_get_serial_port_data(port);
  	unsigned long flags;
  	bool rts;
  	bool changed = false;
  	int ret;
  
  	/* We only support RTS so we only handle that */
  	spin_lock_irqsave(&priv->lock, flags);
  
  	rts = priv->rts;
  	if (set & TIOCM_RTS)
  		priv->rts = true;
  	if (clear & TIOCM_RTS)
  		priv->rts = false;
  	changed = rts ^ priv->rts;
  	spin_unlock_irqrestore(&priv->lock, flags);
  
  	if (!changed)
  		return 0;
  
  	ret = send_control_msg(port, CONTROL_RTS, !rts);
  	if (ret)
  		return usb_translate_errors(ret);
  
  	return 0;
  }
  
  static int get_serial_info(struct usb_serial_port *port,
  			   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		= port->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,
  			 unsigned int cmd, unsigned long arg)
  {
  	struct usb_serial_port *port = tty->driver_data;
  
  	switch (cmd) {
  	case TIOCGSERIAL:
  		return get_serial_info(port,
  				       (struct serial_struct __user *)arg);
  	}
  
  	return -ENOIOCTLCMD;
  }
  
  static int opticon_startup(struct usb_serial *serial)
  {
  	if (!serial->num_bulk_in) {
  		dev_err(&serial->dev->dev, "no bulk in endpoint
  ");
  		return -ENODEV;
  	}
  
  	return 0;
  }
  
  static int opticon_port_probe(struct usb_serial_port *port)
  {
  	struct opticon_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 opticon_port_remove(struct usb_serial_port *port)
  {
  	struct opticon_private *priv = usb_get_serial_port_data(port);
  
  	kfree(priv);
  
  	return 0;
  }
  
  static struct usb_serial_driver opticon_device = {
  	.driver = {
  		.owner =	THIS_MODULE,
  		.name =		"opticon",
  	},
  	.id_table =		id_table,
  	.num_ports =		1,
  	.bulk_in_size =		256,
  	.attach =		opticon_startup,
  	.port_probe =		opticon_port_probe,
  	.port_remove =		opticon_port_remove,
  	.open =			opticon_open,
  	.write =		opticon_write,
  	.write_room = 		opticon_write_room,
  	.throttle =		usb_serial_generic_throttle,
  	.unthrottle =		usb_serial_generic_unthrottle,
  	.ioctl =		opticon_ioctl,
  	.tiocmget =		opticon_tiocmget,
  	.tiocmset =		opticon_tiocmset,
  	.process_read_urb =	opticon_process_read_urb,
  };
  
  static struct usb_serial_driver * const serial_drivers[] = {
  	&opticon_device, NULL
  };
  
  module_usb_serial_driver(serial_drivers, id_table);
  
  MODULE_DESCRIPTION(DRIVER_DESC);
  MODULE_LICENSE("GPL");