touchwin.c

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/*
 * Touchwindow serial touchscreen driver
 *
 * Copyright (c) 2006 Rick Koch <[email protected]>
 *
 * Based on MicroTouch driver (drivers/input/touchscreen/mtouch.c)
 * Copyright (c) 2004 Vojtech Pavlik
 * and Dan Streetman <[email protected]>
 */

/*
 * 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 <[email protected]>");
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,
};

module_serio_driver(tw_drv);