/*
 * MicroTouch (3M) serial touchscreen driver
 *
 * Copyright (c) 2004 Vojtech Pavlik
 */

/*
 * 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 Dan Streetman <ddstreet@ieee.org>
 *   Copied elo.c and edited for MicroTouch 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     "MicroTouch serial touchscreen driver"

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

/*
 * Definitions & global arrays.
 */

#define MTOUCH_FORMAT_TABLET_STATUS_BIT 0x80
#define MTOUCH_FORMAT_TABLET_TOUCH_BIT 0x40
#define MTOUCH_FORMAT_TABLET_LENGTH 5
#define MTOUCH_RESPONSE_BEGIN_BYTE 0x01
#define MTOUCH_RESPONSE_END_BYTE 0x0d

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

#define MTOUCH_MIN_XC 0
#define MTOUCH_MAX_XC 0x3fff
#define MTOUCH_MIN_YC 0
#define MTOUCH_MAX_YC 0x3fff

#define MTOUCH_GET_XC(data) (((data[2])<<7) | data[1])
#define MTOUCH_GET_YC(data) (((data[4])<<7) | data[3])
#define MTOUCH_GET_TOUCHED(data) (MTOUCH_FORMAT_TABLET_TOUCH_BIT & data[0])

/*
 * Per-touchscreen data.
 */

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

static void mtouch_process_format_tablet(struct mtouch *mtouch)
{
        struct input_dev *dev = mtouch->dev;

        if (MTOUCH_FORMAT_TABLET_LENGTH == ++mtouch->idx) {
                input_report_abs(dev, ABS_X, MTOUCH_GET_XC(mtouch->data));
                input_report_abs(dev, ABS_Y, MTOUCH_MAX_YC - MTOUCH_GET_YC(mtouch->data));
                input_report_key(dev, BTN_TOUCH, MTOUCH_GET_TOUCHED(mtouch->data));
                input_sync(dev);

                mtouch->idx = 0;
        }
}

static void mtouch_process_response(struct mtouch *mtouch)
{
        if (MTOUCH_RESPONSE_END_BYTE == mtouch->data[mtouch->idx++]) {
                /* FIXME - process response */
                mtouch->idx = 0;
        } else if (MTOUCH_MAX_LENGTH == mtouch->idx) {
                printk(KERN_ERR "mtouch.c: too many response bytes\n");
                mtouch->idx = 0;
        }
}

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

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

        if (MTOUCH_FORMAT_TABLET_STATUS_BIT & mtouch->data[0])
                mtouch_process_format_tablet(mtouch);
        else if (MTOUCH_RESPONSE_BEGIN_BYTE == mtouch->data[0])
                mtouch_process_response(mtouch);
        else
                printk(KERN_DEBUG "mtouch.c: unknown/unsynchronized data from device, byte %x\n",mtouch->data[0]);

        return IRQ_HANDLED;
}

/*
 * mtouch_disconnect() is the opposite of mtouch_connect()
 */

static void mtouch_disconnect(struct serio *serio)
{
        struct mtouch* mtouch = serio_get_drvdata(serio);

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

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

static int mtouch_connect(struct serio *serio, struct serio_driver *drv)
{
        struct mtouch *mtouch;
        struct input_dev *input_dev;
        int err;

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

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

        input_dev->name = "MicroTouch Serial TouchScreen";
        input_dev->phys = mtouch->phys;
        input_dev->id.bustype = BUS_RS232;
        input_dev->id.vendor = SERIO_MICROTOUCH;
        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(mtouch->dev, ABS_X, MTOUCH_MIN_XC, MTOUCH_MAX_XC, 0, 0);
        input_set_abs_params(mtouch->dev, ABS_Y, MTOUCH_MIN_YC, MTOUCH_MAX_YC, 0, 0);

        serio_set_drvdata(serio, mtouch);

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

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

        return 0;

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

/*
 * The serio driver structure.
 */

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

MODULE_DEVICE_TABLE(serio, mtouch_serio_ids);

static struct serio_driver mtouch_drv = {
        .driver         = {
                .name   = "mtouch",
        },
        .description    = DRIVER_DESC,
        .id_table       = mtouch_serio_ids,
        .interrupt      = mtouch_interrupt,
        .connect        = mtouch_connect,
        .disconnect     = mtouch_disconnect,
};

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

static int __init mtouch_init(void)
{
        return serio_register_driver(&mtouch_drv);
}

static void __exit mtouch_exit(void)
{
        serio_unregister_driver(&mtouch_drv);
}

module_init(mtouch_init);
module_exit(mtouch_exit);