/*
   * Sahara TouchIT-213 serial touchscreen driver
   *
   * Copyright (c) 2007-2008 Claudio Nieder <private@claudio.ch>
   *
   * Based on Touchright driver (drivers/input/touchscreen/touchright.c)
   * Copyright (c) 2006 Rick Koch <n1gp@hotmail.com>
   * Copyright (c) 2004 Vojtech Pavlik
   * and Dan Streetman <ddstreet@ieee.org>
   */
  
  /*
   * 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/errno.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/slab.h>
  #include <linux/input.h>
  #include <linux/serio.h>
  
  #define DRIVER_DESC	"Sahara TouchIT-213 serial touchscreen driver"
  
  MODULE_AUTHOR("Claudio Nieder <private@claudio.ch>");
  MODULE_DESCRIPTION(DRIVER_DESC);
  MODULE_LICENSE("GPL");
  
  /*
   * Definitions & global arrays.
   */
  
  /*
   * Data is received through COM1 at 9600bit/s,8bit,no parity in packets
   * of 5 byte each.
   *
   *   +--------+   +--------+   +--------+   +--------+   +--------+
   *   |1000000p|   |0xxxxxxx|   |0xxxxxxx|   |0yyyyyyy|   |0yyyyyyy|
   *   +--------+   +--------+   +--------+   +--------+   +--------+
   *                    MSB          LSB          MSB          LSB
   *
   * The value of p is 1 as long as the screen is touched and 0 when
   * reporting the location where touching stopped, e.g. where the pen was
   * lifted from the screen.
   *
   * When holding the screen in landscape mode as the BIOS text output is
   * presented, x is the horizontal axis with values growing from left to
   * right and y is the vertical axis with values growing from top to
   * bottom.
   *
   * When holding the screen in portrait mode with the Sahara logo in its
   * correct position, x ist the vertical axis with values growing from
   * top to bottom and y is the horizontal axis with values growing from
   * right to left.
   */
  
  #define T213_FORMAT_TOUCH_BIT	0x01
  #define T213_FORMAT_STATUS_BYTE	0x80
  #define T213_FORMAT_STATUS_MASK	~T213_FORMAT_TOUCH_BIT
  
  /*
   * On my Sahara Touch-IT 213 I have observed x values from 0 to 0x7f0
   * and y values from 0x1d to 0x7e9, so the actual measurement is
   * probably done with an 11 bit precision.
   */
  #define T213_MIN_XC 0
  #define T213_MAX_XC 0x07ff
  #define T213_MIN_YC 0
  #define T213_MAX_YC 0x07ff
  
  /*
   * Per-touchscreen data.
   */
  
  struct touchit213 {
  	struct input_dev *dev;
  	struct serio *serio;
  	int idx;
  	unsigned char csum;
  	unsigned char data[5];
  	char phys[32];
  };
  
  static irqreturn_t touchit213_interrupt(struct serio *serio,
  		unsigned char data, unsigned int flags)
  {
  	struct touchit213 *touchit213 = serio_get_drvdata(serio);
  	struct input_dev *dev = touchit213->dev;
  
  	touchit213->data[touchit213->idx] = data;
  
  	switch (touchit213->idx++) {
  	case 0:
  		if ((touchit213->data[0] & T213_FORMAT_STATUS_MASK) !=
  				T213_FORMAT_STATUS_BYTE) {
  			pr_debug("unsynchronized data: 0x%02x
  ", data);
  			touchit213->idx = 0;
  		}
  		break;
  
  	case 4:
  		touchit213->idx = 0;
  		input_report_abs(dev, ABS_X,
  			(touchit213->data[1] << 7) | touchit213->data[2]);
  		input_report_abs(dev, ABS_Y,
  			(touchit213->data[3] << 7) | touchit213->data[4]);
  		input_report_key(dev, BTN_TOUCH,
  			touchit213->data[0] & T213_FORMAT_TOUCH_BIT);
  		input_sync(dev);
  		break;
  	}
  
  	return IRQ_HANDLED;
  }
  
  /*
   * touchit213_disconnect() is the opposite of touchit213_connect()
   */
  
  static void touchit213_disconnect(struct serio *serio)
  {
  	struct touchit213 *touchit213 = serio_get_drvdata(serio);
  
  	input_get_device(touchit213->dev);
  	input_unregister_device(touchit213->dev);
  	serio_close(serio);
  	serio_set_drvdata(serio, NULL);
  	input_put_device(touchit213->dev);
  	kfree(touchit213);
  }
  
  /*
   * touchit213_connect() is the routine that is called when someone adds a
   * new serio device that supports the Touchright protocol and registers it as
   * an input device.
   */
  
  static int touchit213_connect(struct serio *serio, struct serio_driver *drv)
  {
  	struct touchit213 *touchit213;
  	struct input_dev *input_dev;
  	int err;
  
  	touchit213 = kzalloc(sizeof(struct touchit213), GFP_KERNEL);
  	input_dev = input_allocate_device();
  	if (!touchit213 || !input_dev) {
  		err = -ENOMEM;
  		goto fail1;
  	}
  
  	touchit213->serio = serio;
  	touchit213->dev = input_dev;
  	snprintf(touchit213->phys, sizeof(touchit213->phys),
  		 "%s/input0", serio->phys);
  
  	input_dev->name = "Sahara Touch-iT213 Serial TouchScreen";
  	input_dev->phys = touchit213->phys;
  	input_dev->id.bustype = BUS_RS232;
  	input_dev->id.vendor = SERIO_TOUCHIT213;
  	input_dev->id.product = 0;
  	input_dev->id.version = 0x0100;
  	input_dev->dev.parent = &serio->dev;
  	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
  	input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
  	input_set_abs_params(touchit213->dev, ABS_X,
  			     T213_MIN_XC, T213_MAX_XC, 0, 0);
  	input_set_abs_params(touchit213->dev, ABS_Y,
  			     T213_MIN_YC, T213_MAX_YC, 0, 0);
  
  	serio_set_drvdata(serio, touchit213);
  
  	err = serio_open(serio, drv);
  	if (err)
  		goto fail2;
  
  	err = input_register_device(touchit213->dev);
  	if (err)
  		goto fail3;
  
  	return 0;
  
   fail3:	serio_close(serio);
   fail2:	serio_set_drvdata(serio, NULL);
   fail1:	input_free_device(input_dev);
  	kfree(touchit213);
  	return err;
  }
  
  /*
   * The serio driver structure.
   */
  
  static struct serio_device_id touchit213_serio_ids[] = {
  	{
  		.type	= SERIO_RS232,
  		.proto	= SERIO_TOUCHIT213,
  		.id	= SERIO_ANY,
  		.extra	= SERIO_ANY,
  	},
  	{ 0 }
  };
  
  MODULE_DEVICE_TABLE(serio, touchit213_serio_ids);
  
  static struct serio_driver touchit213_drv = {
  	.driver		= {
  		.name	= "touchit213",
  	},
  	.description	= DRIVER_DESC,
  	.id_table	= touchit213_serio_ids,
  	.interrupt	= touchit213_interrupt,
  	.connect	= touchit213_connect,
  	.disconnect	= touchit213_disconnect,
  };
  
  module_serio_driver(touchit213_drv);