twidjoy.c

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/*
 *  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 <[email protected]>
 */

/*
 * 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,
};

module_serio_driver(twidjoy_drv);