/*
 * iNexio serial touchscreen driver
 *
 * Copyright (c) 2008 Richard Lemon
 * Based on the mtouch driver (c) Vojtech Pavlik and Dan Streetman
 *
 */

/*
 * 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.
 */

/*
 * 2008/06/19 Richard Lemon <richard@codelemon.com>
 *   Copied mtouch.c and edited for iNexio protocol
 */

#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     "iNexio serial touchscreen driver"

MODULE_AUTHOR("Richard Lemon <richard@codelemon.com>");
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");

/*
 * Definitions & global arrays.
 */

#define INEXIO_FORMAT_TOUCH_BIT 0x01
#define INEXIO_FORMAT_LENGTH 5
#define INEXIO_RESPONSE_BEGIN_BYTE 0x80

/* todo: check specs for max length of all responses */
#define INEXIO_MAX_LENGTH 16

#define INEXIO_MIN_XC 0
#define INEXIO_MAX_XC 0x3fff
#define INEXIO_MIN_YC 0
#define INEXIO_MAX_YC 0x3fff

#define INEXIO_GET_XC(data) (((data[1])<<7) | data[2])
#define INEXIO_GET_YC(data) (((data[3])<<7) | data[4])
#define INEXIO_GET_TOUCHED(data) (INEXIO_FORMAT_TOUCH_BIT & data[0])

/*
 * Per-touchscreen data.
 */

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

static void inexio_process_data(struct inexio *pinexio)
{
        struct input_dev *dev = pinexio->dev;

        if (INEXIO_FORMAT_LENGTH == ++pinexio->idx) {
                input_report_abs(dev, ABS_X, INEXIO_GET_XC(pinexio->data));
                input_report_abs(dev, ABS_Y, INEXIO_GET_YC(pinexio->data));
                input_report_key(dev, BTN_TOUCH, INEXIO_GET_TOUCHED(pinexio->data));
                input_sync(dev);

                pinexio->idx = 0;
        }
}

static irqreturn_t inexio_interrupt(struct serio *serio,
                unsigned char data, unsigned int flags)
{
        struct inexio* pinexio = serio_get_drvdata(serio);

        pinexio->data[pinexio->idx] = data;

        if (INEXIO_RESPONSE_BEGIN_BYTE&pinexio->data[0])
                inexio_process_data(pinexio);
        else
                printk(KERN_DEBUG "inexio.c: unknown/unsynchronized data from device, byte %x\n",pinexio->data[0]);

        return IRQ_HANDLED;
}

/*
 * inexio_disconnect() is the opposite of inexio_connect()
 */

static void inexio_disconnect(struct serio *serio)
{
        struct inexio* pinexio = serio_get_drvdata(serio);

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

/*
 * inexio_connect() is the routine that is called when someone adds a
 * new serio device that supports iNexio protocol and registers it as
 * an input device. This is usually accomplished using inputattach.
 */

static int inexio_connect(struct serio *serio, struct serio_driver *drv)
{
        struct inexio *pinexio;
        struct input_dev *input_dev;
        int err;

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

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

        input_dev->name = "iNexio Serial TouchScreen";
        input_dev->phys = pinexio->phys;
        input_dev->id.bustype = BUS_RS232;
        input_dev->id.vendor = SERIO_INEXIO;
        input_dev->id.product = 0;
        input_dev->id.version = 0x0001;
        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(pinexio->dev, ABS_X, INEXIO_MIN_XC, INEXIO_MAX_XC, 0, 0);
        input_set_abs_params(pinexio->dev, ABS_Y, INEXIO_MIN_YC, INEXIO_MAX_YC, 0, 0);

        serio_set_drvdata(serio, pinexio);

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

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

        return 0;

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

/*
 * The serio driver structure.
 */

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

MODULE_DEVICE_TABLE(serio, inexio_serio_ids);

static struct serio_driver inexio_drv = {
        .driver         = {
                .name   = "inexio",
        },
        .description    = DRIVER_DESC,
        .id_table       = inexio_serio_ids,
        .interrupt      = inexio_interrupt,
        .connect        = inexio_connect,
        .disconnect     = inexio_disconnect,
};

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

static int __init inexio_init(void)
{
        return serio_register_driver(&inexio_drv);
}

static void __exit inexio_exit(void)
{
        serio_unregister_driver(&inexio_drv);
}

module_init(inexio_init);
module_exit(inexio_exit);