/*
   * USB ZyXEL omni.net LCD PLUS driver
   *
   *	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.
   *
   * See Documentation/usb/usb-serial.txt for more information on using this
   * driver
   *
   * Please report both successes and troubles to the author at omninet@kroah.com
   */
  
  #include <linux/kernel.h>
  #include <linux/errno.h>
  #include <linux/slab.h>
  #include <linux/tty.h>
  #include <linux/tty_driver.h>
  #include <linux/tty_flip.h>
  #include <linux/module.h>
  #include <linux/uaccess.h>
  #include <linux/usb.h>
  #include <linux/usb/serial.h>
  
  #define DRIVER_AUTHOR "Alessandro Zummo"
  #define DRIVER_DESC "USB ZyXEL omni.net LCD PLUS Driver"
  
  #define ZYXEL_VENDOR_ID		0x0586
  #define ZYXEL_OMNINET_ID	0x1000
  /* This one seems to be a re-branded ZyXEL device */
  #define BT_IGNITIONPRO_ID	0x2000
  
  /* function prototypes */
  static int  omninet_open(struct tty_struct *tty, struct usb_serial_port *port);
  static void omninet_process_read_urb(struct urb *urb);
  static void omninet_write_bulk_callback(struct urb *urb);
  static int  omninet_write(struct tty_struct *tty, struct usb_serial_port *port,
  				const unsigned char *buf, int count);
  static int  omninet_write_room(struct tty_struct *tty);
  static void omninet_disconnect(struct usb_serial *serial);
  static int omninet_port_probe(struct usb_serial_port *port);
  static int omninet_port_remove(struct usb_serial_port *port);
  
  static const struct usb_device_id id_table[] = {
  	{ USB_DEVICE(ZYXEL_VENDOR_ID, ZYXEL_OMNINET_ID) },
  	{ USB_DEVICE(ZYXEL_VENDOR_ID, BT_IGNITIONPRO_ID) },
  	{ }						/* Terminating entry */
  };
  MODULE_DEVICE_TABLE(usb, id_table);
  
  static struct usb_serial_driver zyxel_omninet_device = {
  	.driver = {
  		.owner =	THIS_MODULE,
  		.name =		"omninet",
  	},
  	.description =		"ZyXEL - omni.net lcd plus usb",
  	.id_table =		id_table,
  	.num_ports =		1,
  	.port_probe =		omninet_port_probe,
  	.port_remove =		omninet_port_remove,
  	.open =			omninet_open,
  	.write =		omninet_write,
  	.write_room =		omninet_write_room,
  	.write_bulk_callback =	omninet_write_bulk_callback,
  	.process_read_urb =	omninet_process_read_urb,
  	.disconnect =		omninet_disconnect,
  };
  
  static struct usb_serial_driver * const serial_drivers[] = {
  	&zyxel_omninet_device, NULL
  };
  
  
  /*
   * The protocol.
   *
   * The omni.net always exchange 64 bytes of data with the host. The first
   * four bytes are the control header.
   *
   * oh_seq is a sequence number. Don't know if/how it's used.
   * oh_len is the length of the data bytes in the packet.
   * oh_xxx Bit-mapped, related to handshaking and status info.
   *	I normally set it to 0x03 in transmitted frames.
   *	7: Active when the TA is in a CONNECTed state.
   *	6: unknown
   *	5: handshaking, unknown
   *	4: handshaking, unknown
   *	3: unknown, usually 0
   *	2: unknown, usually 0
   *	1: handshaking, unknown, usually set to 1 in transmitted frames
   *	0: handshaking, unknown, usually set to 1 in transmitted frames
   * oh_pad Probably a pad byte.
   *
   * After the header you will find data bytes if oh_len was greater than zero.
   */
  struct omninet_header {
  	__u8	oh_seq;
  	__u8	oh_len;
  	__u8	oh_xxx;
  	__u8	oh_pad;
  };
  
  struct omninet_data {
  	__u8	od_outseq;	/* Sequence number for bulk_out URBs */
  };
  
  static int omninet_port_probe(struct usb_serial_port *port)
  {
  	struct omninet_data *od;
  
  	od = kzalloc(sizeof(*od), GFP_KERNEL);
  	if (!od)
  		return -ENOMEM;
  
  	usb_set_serial_port_data(port, od);
  
  	return 0;
  }
  
  static int omninet_port_remove(struct usb_serial_port *port)
  {
  	struct omninet_data *od;
  
  	od = usb_get_serial_port_data(port);
  	kfree(od);
  
  	return 0;
  }
  
  static int omninet_open(struct tty_struct *tty, struct usb_serial_port *port)
  {
  	struct usb_serial	*serial = port->serial;
  	struct usb_serial_port	*wport;
  
  	wport = serial->port[1];
  	tty_port_tty_set(&wport->port, tty);
  
  	return usb_serial_generic_open(tty, port);
  }
  
  #define OMNINET_HEADERLEN	4
  #define OMNINET_BULKOUTSIZE	64
  #define OMNINET_PAYLOADSIZE	(OMNINET_BULKOUTSIZE - OMNINET_HEADERLEN)
  
  static void omninet_process_read_urb(struct urb *urb)
  {
  	struct usb_serial_port *port = urb->context;
  	const struct omninet_header *hdr = urb->transfer_buffer;
  	const unsigned char *data;
  	size_t data_len;
  
  	if (urb->actual_length <= OMNINET_HEADERLEN || !hdr->oh_len)
  		return;
  
  	data = (char *)urb->transfer_buffer + OMNINET_HEADERLEN;
  	data_len = min_t(size_t, urb->actual_length - OMNINET_HEADERLEN,
  								hdr->oh_len);
  	tty_insert_flip_string(&port->port, data, data_len);
  	tty_flip_buffer_push(&port->port);
  }
  
  static int omninet_write(struct tty_struct *tty, struct usb_serial_port *port,
  					const unsigned char *buf, int count)
  {
  	struct usb_serial *serial = port->serial;
  	struct usb_serial_port *wport = serial->port[1];
  
  	struct omninet_data *od = usb_get_serial_port_data(port);
  	struct omninet_header *header = (struct omninet_header *)
  					wport->write_urb->transfer_buffer;
  
  	int			result;
  
  	if (count == 0) {
  		dev_dbg(&port->dev, "%s - write request of 0 bytes
  ", __func__);
  		return 0;
  	}
  
  	if (!test_and_clear_bit(0, &port->write_urbs_free)) {
  		dev_dbg(&port->dev, "%s - already writing
  ", __func__);
  		return 0;
  	}
  
  	count = (count > OMNINET_PAYLOADSIZE) ? OMNINET_PAYLOADSIZE : count;
  
  	memcpy(wport->write_urb->transfer_buffer + OMNINET_HEADERLEN,
  								buf, count);
  
  	usb_serial_debug_data(&port->dev, __func__, count,
  			      wport->write_urb->transfer_buffer);
  
  	header->oh_seq 	= od->od_outseq++;
  	header->oh_len 	= count;
  	header->oh_xxx  = 0x03;
  	header->oh_pad 	= 0x00;
  
  	/* send the data out the bulk port, always 64 bytes */
  	wport->write_urb->transfer_buffer_length = OMNINET_BULKOUTSIZE;
  
  	result = usb_submit_urb(wport->write_urb, GFP_ATOMIC);
  	if (result) {
  		set_bit(0, &wport->write_urbs_free);
  		dev_err_console(port,
  			"%s - failed submitting write urb, error %d
  ",
  			__func__, result);
  	} else
  		result = count;
  
  	return result;
  }
  
  
  static int omninet_write_room(struct tty_struct *tty)
  {
  	struct usb_serial_port *port = tty->driver_data;
  	struct usb_serial 	*serial = port->serial;
  	struct usb_serial_port 	*wport 	= serial->port[1];
  
  	int room = 0; /* Default: no room */
  
  	if (test_bit(0, &wport->write_urbs_free))
  		room = wport->bulk_out_size - OMNINET_HEADERLEN;
  
  	dev_dbg(&port->dev, "%s - returns %d
  ", __func__, room);
  
  	return room;
  }
  
  static void omninet_write_bulk_callback(struct urb *urb)
  {
  /*	struct omninet_header	*header = (struct omninet_header  *)
  						urb->transfer_buffer; */
  	struct usb_serial_port 	*port   =  urb->context;
  	int status = urb->status;
  
  	set_bit(0, &port->write_urbs_free);
  	if (status) {
  		dev_dbg(&port->dev, "%s - nonzero write bulk status received: %d
  ",
  			__func__, status);
  		return;
  	}
  
  	usb_serial_port_softint(port);
  }
  
  
  static void omninet_disconnect(struct usb_serial *serial)
  {
  	struct usb_serial_port *wport = serial->port[1];
  
  	usb_kill_urb(wport->write_urb);
  }
  
  module_usb_serial_driver(serial_drivers, id_table);
  
  MODULE_AUTHOR(DRIVER_AUTHOR);
  MODULE_DESCRIPTION(DRIVER_DESC);
  MODULE_LICENSE("GPL");