// SPDX-License-Identifier: GPL-2.0-only
/*
 * 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>
 */


/*
 * 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>

#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_obj(*tw);
        input_dev = input_allocate_device();
        if (!tw || !input_dev) {
                err = -ENOMEM;
                goto fail1;
        }

        tw->serio = serio;
        tw->dev = input_dev;
        scnprintf(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 const 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);