// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  Copyright (c) 2000-2001 Vojtech Pavlik
 */

/*
 * Gunze AHL-51S touchscreen driver for Linux
 */

#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     "Gunze AHL-51S touchscreen driver"

MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");

/*
 * Definitions & global arrays.
 */

#define GUNZE_MAX_LENGTH        10

/*
 * Per-touchscreen data.
 */

struct gunze {
        struct input_dev *dev;
        struct serio *serio;
        int idx;
        unsigned char data[GUNZE_MAX_LENGTH];
        char phys[32];
};

static void gunze_process_packet(struct gunze *gunze)
{
        struct input_dev *dev = gunze->dev;

        if (gunze->idx != GUNZE_MAX_LENGTH || gunze->data[5] != ',' ||
                (gunze->data[0] != 'T' && gunze->data[0] != 'R')) {
                printk(KERN_WARNING "gunze.c: bad packet: >%.*s<\n", GUNZE_MAX_LENGTH, gunze->data);
                return;
        }

        input_report_abs(dev, ABS_X, simple_strtoul(gunze->data + 1, NULL, 10));
        input_report_abs(dev, ABS_Y, 1024 - simple_strtoul(gunze->data + 6, NULL, 10));
        input_report_key(dev, BTN_TOUCH, gunze->data[0] == 'T');
        input_sync(dev);
}

static irqreturn_t gunze_interrupt(struct serio *serio,
                unsigned char data, unsigned int flags)
{
        struct gunze *gunze = serio_get_drvdata(serio);

        if (data == '\r') {
                gunze_process_packet(gunze);
                gunze->idx = 0;
        } else {
                if (gunze->idx < GUNZE_MAX_LENGTH)
                        gunze->data[gunze->idx++] = data;
        }
        return IRQ_HANDLED;
}

/*
 * gunze_disconnect() is the opposite of gunze_connect()
 */

static void gunze_disconnect(struct serio *serio)
{
        struct gunze *gunze = serio_get_drvdata(serio);

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

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

static int gunze_connect(struct serio *serio, struct serio_driver *drv)
{
        struct gunze *gunze;
        struct input_dev *input_dev;
        int err;

        gunze = kzalloc_obj(*gunze);
        input_dev = input_allocate_device();
        if (!gunze || !input_dev) {
                err = -ENOMEM;
                goto fail1;
        }

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

        input_dev->name = "Gunze AHL-51S TouchScreen";
        input_dev->phys = gunze->phys;
        input_dev->id.bustype = BUS_RS232;
        input_dev->id.vendor = SERIO_GUNZE;
        input_dev->id.product = 0x0051;
        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(input_dev, ABS_X, 24, 1000, 0, 0);
        input_set_abs_params(input_dev, ABS_Y, 24, 1000, 0, 0);

        serio_set_drvdata(serio, gunze);

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

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

        return 0;

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

/*
 * The serio driver structure.
 */

static const struct serio_device_id gunze_serio_ids[] = {
        {
                .type   = SERIO_RS232,
                .proto  = SERIO_GUNZE,
                .id     = SERIO_ANY,
                .extra  = SERIO_ANY,
        },
        { 0 }
};

MODULE_DEVICE_TABLE(serio, gunze_serio_ids);

static struct serio_driver gunze_drv = {
        .driver         = {
                .name   = "gunze",
        },
        .description    = DRIVER_DESC,
        .id_table       = gunze_serio_ids,
        .interrupt      = gunze_interrupt,
        .connect        = gunze_connect,
        .disconnect     = gunze_disconnect,
};

module_serio_driver(gunze_drv);