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touchwin.c

/*
 * Touchwindow serial touchscreen driver
 *
 * Copyright (c) 2006 Rick Koch <n1gp@hotmail.com>
 *
 * Based on MicroTouch driver (drivers/input/touchscreen/mtouch.c)
 * 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.
 */

/*
 * 2005/02/19 Rick Koch:
 *   The Touchwindow I used is made by Edmark Corp. and
 *   constantly outputs a stream of 0's unless it is touched.
 *   It then outputs 3 bytes: X, Y, and a copy of Y.
 */

#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/input.h>
#include <linux/serio.h>
#include <linux/init.h>

#define DRIVER_DESC     "Touchwindow serial touchscreen driver"

MODULE_AUTHOR("Rick Koch <n1gp@hotmail.com>");
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");

/*
 * Definitions & global arrays.
 */

#define TW_LENGTH 3

#define TW_MIN_XC 0
#define TW_MAX_XC 0xff
#define TW_MIN_YC 0
#define TW_MAX_YC 0xff

/*
 * Per-touchscreen data.
 */

struct tw {
      struct input_dev *dev;
      struct serio *serio;
      int idx;
      int touched;
      unsigned char data[TW_LENGTH];
      char phys[32];
};

static irqreturn_t tw_interrupt(struct serio *serio,
            unsigned char data, unsigned int flags)
{
      struct tw *tw = serio_get_drvdata(serio);
      struct input_dev *dev = tw->dev;

      if (data) {       /* touch */
            tw->touched = 1;
            tw->data[tw->idx++] = data;
            /* verify length and that the two Y's are the same */
            if (tw->idx == TW_LENGTH && tw->data[1] == tw->data[2]) {
                  input_report_abs(dev, ABS_X, tw->data[0]);
                  input_report_abs(dev, ABS_Y, tw->data[1]);
                  input_report_key(dev, BTN_TOUCH, 1);
                  input_sync(dev);
                  tw->idx = 0;
            }
      } else if (tw->touched) {     /* untouch */
            input_report_key(dev, BTN_TOUCH, 0);
            input_sync(dev);
            tw->idx = 0;
            tw->touched = 0;
      }

      return IRQ_HANDLED;
}

/*
 * tw_disconnect() is the opposite of tw_connect()
 */

static void tw_disconnect(struct serio *serio)
{
      struct tw *tw = serio_get_drvdata(serio);

      input_get_device(tw->dev);
      input_unregister_device(tw->dev);
      serio_close(serio);
      serio_set_drvdata(serio, NULL);
      input_put_device(tw->dev);
      kfree(tw);
}

/*
 * tw_connect() is the routine that is called when someone adds a
 * new serio device that supports the Touchwin protocol and registers it as
 * an input device.
 */

static int tw_connect(struct serio *serio, struct serio_driver *drv)
{
      struct tw *tw;
      struct input_dev *input_dev;
      int err;

      tw = kzalloc(sizeof(struct tw), GFP_KERNEL);
      input_dev = input_allocate_device();
      if (!tw || !input_dev) {
            err = -ENOMEM;
            goto fail1;
      }

      tw->serio = serio;
      tw->dev = input_dev;
      snprintf(tw->phys, sizeof(tw->phys), "%s/input0", serio->phys);

      input_dev->name = "Touchwindow Serial TouchScreen";
      input_dev->phys = tw->phys;
      input_dev->id.bustype = BUS_RS232;
      input_dev->id.vendor = SERIO_TOUCHWIN;
      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(tw->dev, ABS_X, TW_MIN_XC, TW_MAX_XC, 0, 0);
      input_set_abs_params(tw->dev, ABS_Y, TW_MIN_YC, TW_MAX_YC, 0, 0);

      serio_set_drvdata(serio, tw);

      err = serio_open(serio, drv);
      if (err)
            goto fail2;

      err = input_register_device(tw->dev);
      if (err)
            goto fail3;

      return 0;

 fail3:     serio_close(serio);
 fail2:     serio_set_drvdata(serio, NULL);
 fail1:     input_free_device(input_dev);
      kfree(tw);
      return err;
}

/*
 * The serio driver structure.
 */

static struct serio_device_id tw_serio_ids[] = {
      {
            .type = SERIO_RS232,
            .proto      = SERIO_TOUCHWIN,
            .id   = SERIO_ANY,
            .extra      = SERIO_ANY,
      },
      { 0 }
};

MODULE_DEVICE_TABLE(serio, tw_serio_ids);

static struct serio_driver tw_drv = {
      .driver           = {
            .name = "touchwin",
      },
      .description      = DRIVER_DESC,
      .id_table   = tw_serio_ids,
      .interrupt  = tw_interrupt,
      .connect    = tw_connect,
      .disconnect = tw_disconnect,
};

/*
 * The functions for inserting/removing us as a module.
 */

static int __init tw_init(void)
{
      return serio_register_driver(&tw_drv);
}

static void __exit tw_exit(void)
{
      serio_unregister_driver(&tw_drv);
}

module_init(tw_init);
module_exit(tw_exit);

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