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/*

 * $Id: twidjoy.c,v 1.5 2002/01/22 20:31:53 vojtech Exp $

 *

 *  derived from CVS-ID "stinger.c,v 1.5 2001/05/29 12:57:18 vojtech Exp"

 *

 *  Copyright (c) 2001 Arndt Schoenewald

 *  Copyright (c) 2000-2001 Vojtech Pavlik

 *  Copyright (c) 2000 Mark Fletcher

 *

 *  Sponsored by Quelltext AG (http://www.quelltext-ag.de), Dortmund, Germany

 */

/*

 * Driver to use Handykey's Twiddler (the first edition, i.e. the one with

 * the RS232 interface) as a joystick under Linux

 *

 * The Twiddler is a one-handed chording keyboard featuring twelve buttons on

 * the front, six buttons on the top, and a built-in tilt sensor. The buttons

 * on the front, which are grouped as four rows of three buttons, are pressed

 * by the four fingers (this implies only one button per row can be held down

 * at the same time) and the buttons on the top are for the thumb. The tilt

 * sensor delivers X and Y axis data depending on how the Twiddler is held.

 * Additional information can be found at http://www.handykey.com.

 *

 * This driver does not use the Twiddler for its intended purpose, i.e. as

 * a chording keyboard, but as a joystick: pressing and releasing a button

 * immediately sends a corresponding button event, and tilting it generates

 * corresponding ABS_X and ABS_Y events. This turns the Twiddler into a game

 * controller with amazing 18 buttons :-)

 *

 * Note: The Twiddler2 (the successor of the Twiddler that connects directly

 * to the PS/2 keyboard and mouse ports) is NOT supported by this driver!

 *

 * For questions or feedback regarding this driver module please contact:

 * Arndt Schoenewald <arndt@quelltext.com>

 */

/*

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA

 */

#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     "Handykey Twiddler keyboard as a joystick driver"

MODULE_DESCRIPTION(DRIVER_DESC);

MODULE_LICENSE("GPL");

/*

 * Constants.

 */

#define TWIDJOY_MAX_LENGTH 5

static struct twidjoy_button_spec {

        int bitshift;

        int bitmask;

        int buttons[3];

}

twidjoy_buttons[] = {

        {  0, 3, { BTN_A,      BTN_B,     BTN_C    } },

        {  2, 3, { BTN_X,      BTN_Y,     BTN_Z    } },

        {  4, 3, { BTN_TL,     BTN_TR,    BTN_TR2  } },

        {  6, 3, { BTN_SELECT, BTN_START, BTN_MODE } },

        {  8, 1, { BTN_BASE5                       } },

        {  9, 1, { BTN_BASE                        } },

        { 10, 1, { BTN_BASE3                       } },

        { 11, 1, { BTN_BASE4                       } },

        { 12, 1, { BTN_BASE2                       } },

        { 13, 1, { BTN_BASE6                       } },

        { 0,  0, { 0                               } }

};

/*

 * Per-Twiddler data.

 */

struct twidjoy {

        struct input_dev *dev;

        int idx;

        unsigned char data[TWIDJOY_MAX_LENGTH];

        char phys[32];

};

/*

 * twidjoy_process_packet() decodes packets the driver receives from the

 * Twiddler. It updates the data accordingly.

 */

static void twidjoy_process_packet(struct twidjoy *twidjoy)

{

        struct input_dev *dev = twidjoy->dev;

        unsigned char *data = twidjoy->data;

        struct twidjoy_button_spec *bp;

        int button_bits, abs_x, abs_y;

        button_bits = ((data[1] & 0x7f) << 7) | (data[0] & 0x7f);

        for (bp = twidjoy_buttons; bp->bitmask; bp++) {

                int value = (button_bits & (bp->bitmask << bp->bitshift)) >> bp->bitshift;

                int i;

                for (i = 0; i < bp->bitmask; i++)

                        input_report_key(dev, bp->buttons[i], i+1 == value);

        }

        abs_x = ((data[4] & 0x07) << 5) | ((data[3] & 0x7C) >> 2);

        if (data[4] & 0x08) abs_x -= 256;

        abs_y = ((data[3] & 0x01) << 7) | ((data[2] & 0x7F) >> 0);

        if (data[3] & 0x02) abs_y -= 256;

        input_report_abs(dev, ABS_X, -abs_x);

        input_report_abs(dev, ABS_Y, +abs_y);

        input_sync(dev);

}

/*

 * twidjoy_interrupt() is called by the low level driver when characters

 * are ready for us. We then buffer them for further processing, or call the

 * packet processing routine.

 */

static irqreturn_t twidjoy_interrupt(struct serio *serio, unsigned char data, unsigned int flags)

{

        struct twidjoy *twidjoy = serio_get_drvdata(serio);

        /* All Twiddler packets are 5 bytes. The fact that the first byte

         * has a MSB of 0 and all other bytes have a MSB of 1 can be used

         * to check and regain sync. */

        if ((data & 0x80) == 0)

                twidjoy->idx = 0;        /* this byte starts a new packet */

        else if (twidjoy->idx == 0)

                return IRQ_HANDLED;     /* wrong MSB -- ignore this byte */

        if (twidjoy->idx < TWIDJOY_MAX_LENGTH)

                twidjoy->data[twidjoy->idx++] = data;

        if (twidjoy->idx == TWIDJOY_MAX_LENGTH) {

                twidjoy_process_packet(twidjoy);

                twidjoy->idx = 0;

        }

        return IRQ_HANDLED;

}

/*

 * twidjoy_disconnect() is the opposite of twidjoy_connect()

 */

static void twidjoy_disconnect(struct serio *serio)

{

        struct twidjoy *twidjoy = serio_get_drvdata(serio);

        serio_close(serio);

        serio_set_drvdata(serio, NULL);

        input_unregister_device(twidjoy->dev);

        kfree(twidjoy);

}

/*

 * twidjoy_connect() is the routine that is called when someone adds a

 * new serio device. It looks for the Twiddler, and if found, registers

 * it as an input device.

 */

static int twidjoy_connect(struct serio *serio, struct serio_driver *drv)

{

        struct twidjoy_button_spec *bp;

        struct twidjoy *twidjoy;

        struct input_dev *input_dev;

        int err = -ENOMEM;

        int i;

        twidjoy = kzalloc(sizeof(struct twidjoy), GFP_KERNEL);

        input_dev = input_allocate_device();

        if (!twidjoy || !input_dev)

                goto fail1;

        twidjoy->dev = input_dev;

        snprintf(twidjoy->phys, sizeof(twidjoy->phys), "%s/input0", serio->phys);

        input_dev->name = "Handykey Twiddler";

        input_dev->phys = twidjoy->phys;

        input_dev->id.bustype = BUS_RS232;

        input_dev->id.vendor = SERIO_TWIDJOY;

        input_dev->id.product = 0x0001;

        input_dev->id.version = 0x0100;

        input_dev->dev.parent = &serio->dev;

        input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);

        input_set_abs_params(input_dev, ABS_X, -50, 50, 4, 4);

        input_set_abs_params(input_dev, ABS_Y, -50, 50, 4, 4);

        for (bp = twidjoy_buttons; bp->bitmask; bp++)

                for (i = 0; i < bp->bitmask; i++)

                        set_bit(bp->buttons[i], input_dev->keybit);

        serio_set_drvdata(serio, twidjoy);

        err = serio_open(serio, drv);

        if (err)

                goto fail2;

        err = input_register_device(twidjoy->dev);

        if (err)

                goto fail3;

        return 0;

 fail3: serio_close(serio);

 fail2: serio_set_drvdata(serio, NULL);

 fail1: input_free_device(input_dev);

        kfree(twidjoy);

        return err;

}

/*

 * The serio driver structure.

 */

static struct serio_device_id twidjoy_serio_ids[] = {

        {

                .type   = SERIO_RS232,

                .proto  = SERIO_TWIDJOY,

                .id     = SERIO_ANY,

                .extra  = SERIO_ANY,

        },

        { 0 }

};

MODULE_DEVICE_TABLE(serio, twidjoy_serio_ids);

static struct serio_driver twidjoy_drv = {

        .driver         = {

                .name   = "twidjoy",

        },

        .description    = DRIVER_DESC,

        .id_table       = twidjoy_serio_ids,

        .interrupt      = twidjoy_interrupt,

        .connect        = twidjoy_connect,

        .disconnect     = twidjoy_disconnect,

};

/*

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

 */

static int __init twidjoy_init(void)

{

        return serio_register_driver(&twidjoy_drv);

}

static void __exit twidjoy_exit(void)

{

        serio_unregister_driver(&twidjoy_drv);

}

module_init(twidjoy_init);

module_exit(twidjoy_exit);