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fujitsu_ts.c

/*
 * Fujitsu serial touchscreen driver
 *
 * Copyright (c) Dmitry Torokhov <dtor@mail.ru>
 */

/*
 * 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>
#include <linux/init.h>

#define DRIVER_DESC     "Fujitsu serial touchscreen driver"

MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");

#define FUJITSU_LENGTH 5

/*
 * Per-touchscreen data.
 */
struct fujitsu {
      struct input_dev *dev;
      struct serio *serio;
      int idx;
      unsigned char data[FUJITSU_LENGTH];
      char phys[32];
};

/*
 * Decode serial data (5 bytes per packet)
 * First byte
 * 1 C 0 0 R S S S
 * Where C is 1 while in calibration mode (which we don't use)
 * R is 1 when no coordinate corection was done.
 * S are button state
 */
static irqreturn_t fujitsu_interrupt(struct serio *serio,
                             unsigned char data, unsigned int flags)
{
      struct fujitsu *fujitsu = serio_get_drvdata(serio);
      struct input_dev *dev = fujitsu->dev;

      if (fujitsu->idx == 0) {
            /* resync skip until start of frame */
            if ((data & 0xf0) != 0x80)
                  return IRQ_HANDLED;
      } else {
            /* resync skip garbage */
            if (data & 0x80) {
                  fujitsu->idx = 0;
                  return IRQ_HANDLED;
            }
      }

      fujitsu->data[fujitsu->idx++] = data;
      if (fujitsu->idx == FUJITSU_LENGTH) {
            input_report_abs(dev, ABS_X,
                         (fujitsu->data[2] << 7) | fujitsu->data[1]);
            input_report_abs(dev, ABS_Y,
                         (fujitsu->data[4] << 7) | fujitsu->data[3]);
            input_report_key(dev, BTN_TOUCH,
                         (fujitsu->data[0] & 0x03) != 2);
            input_sync(dev);
            fujitsu->idx = 0;
      }

      return IRQ_HANDLED;
}

/*
 * fujitsu_disconnect() is the opposite of fujitsu_connect()
 */
static void fujitsu_disconnect(struct serio *serio)
{
      struct fujitsu *fujitsu = serio_get_drvdata(serio);

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

/*
 * fujitsu_connect() is the routine that is called when someone adds a
 * new serio device that supports the Fujitsu protocol and registers it
 * as input device.
 */
static int fujitsu_connect(struct serio *serio, struct serio_driver *drv)
{
      struct fujitsu *fujitsu;
      struct input_dev *input_dev;
      int err;

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

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

      input_dev->name = "Fujitsu Serial Touchscreen";
      input_dev->phys = fujitsu->phys;
      input_dev->id.bustype = BUS_RS232;
      input_dev->id.vendor = SERIO_FUJITSU;
      input_dev->id.product = 0;
      input_dev->id.version = 0x0100;
      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(input_dev, ABS_X, 0, 4096, 0, 0);
      input_set_abs_params(input_dev, ABS_Y, 0, 4096, 0, 0);
      serio_set_drvdata(serio, fujitsu);

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

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

      return 0;

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

/*
 * The serio driver structure.
 */
static struct serio_device_id fujitsu_serio_ids[] = {
      {
            .type = SERIO_RS232,
            .proto      = SERIO_FUJITSU,
            .id   = SERIO_ANY,
            .extra      = SERIO_ANY,
      },
      { 0 }
};

MODULE_DEVICE_TABLE(serio, fujitsu_serio_ids);

static struct serio_driver fujitsu_drv = {
      .driver           = {
            .name = "fujitsu_ts",
      },
      .description      = DRIVER_DESC,
      .id_table   = fujitsu_serio_ids,
      .interrupt  = fujitsu_interrupt,
      .connect    = fujitsu_connect,
      .disconnect = fujitsu_disconnect,
};

static int __init fujitsu_init(void)
{
      return serio_register_driver(&fujitsu_drv);
}

static void __exit fujitsu_exit(void)
{
      serio_unregister_driver(&fujitsu_drv);
}

module_init(fujitsu_init);
module_exit(fujitsu_exit);

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