/*
 * Wacom W8001 penabled serial touchscreen driver
 *
 * Copyright (c) 2008 Jaya Kumar
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License. See the file COPYING in the main directory of this archive for
 * more details.
 *
 * Layout based on Elo serial touchscreen driver by Vojtech Pavlik
 */

#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>
#include <linux/ctype.h>

#define DRIVER_DESC     "Wacom W8001 serial touchscreen driver"

MODULE_AUTHOR("Jaya Kumar <jayakumar.lkml@gmail.com>");
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");

#define W8001_MAX_LENGTH        11
#define W8001_LEAD_MASK         0x80
#define W8001_LEAD_BYTE         0x80
#define W8001_TAB_MASK          0x40
#define W8001_TAB_BYTE          0x40

#define W8001_QUERY_PACKET      0x20

#define W8001_CMD_START         '1'
#define W8001_CMD_QUERY         '*'

struct w8001_coord {
        u8 rdy;
        u8 tsw;
        u8 f1;
        u8 f2;
        u16 x;
        u16 y;
        u16 pen_pressure;
        u8 tilt_x;
        u8 tilt_y;
};

/*
 * Per-touchscreen data.
 */

struct w8001 {
        struct input_dev *dev;
        struct serio *serio;
        struct completion cmd_done;
        int id;
        int idx;
        unsigned char response_type;
        unsigned char response[W8001_MAX_LENGTH];
        unsigned char data[W8001_MAX_LENGTH];
        char phys[32];
};

static void parse_data(u8 *data, struct w8001_coord *coord)
{
        memset(coord, 0, sizeof(*coord));

        coord->rdy = data[0] & 0x20;
        coord->tsw = data[0] & 0x01;
        coord->f1 = data[0] & 0x02;
        coord->f2 = data[0] & 0x04;

        coord->x = (data[1] & 0x7F) << 9;
        coord->x |= (data[2] & 0x7F) << 2;
        coord->x |= (data[6] & 0x60) >> 5;

        coord->y = (data[3] & 0x7F) << 9;
        coord->y |= (data[4] & 0x7F) << 2;
        coord->y |= (data[6] & 0x18) >> 3;

        coord->pen_pressure = data[5] & 0x7F;
        coord->pen_pressure |= (data[6] & 0x07) << 7 ;

        coord->tilt_x = data[7] & 0x7F;
        coord->tilt_y = data[8] & 0x7F;
}

static irqreturn_t w8001_interrupt(struct serio *serio,
                                   unsigned char data, unsigned int flags)
{
        struct w8001 *w8001 = serio_get_drvdata(serio);
        struct input_dev *dev = w8001->dev;
        struct w8001_coord coord;
        unsigned char tmp;

        w8001->data[w8001->idx] = data;
        switch (w8001->idx++) {
        case 0:
                if ((data & W8001_LEAD_MASK) != W8001_LEAD_BYTE) {
                        pr_debug("w8001: unsynchronized data: 0x%02x\n", data);
                        w8001->idx = 0;
                }
                break;

        case 8:
                tmp = w8001->data[0] & W8001_TAB_MASK;
                if (unlikely(tmp == W8001_TAB_BYTE))
                        break;

                w8001->idx = 0;
                parse_data(w8001->data, &coord);
                input_report_abs(dev, ABS_X, coord.x);
                input_report_abs(dev, ABS_Y, coord.y);
                input_report_abs(dev, ABS_PRESSURE, coord.pen_pressure);
                input_report_key(dev, BTN_TOUCH, coord.tsw);
                input_sync(dev);
                break;

        case 10:
                w8001->idx = 0;
                memcpy(w8001->response, w8001->data, W8001_MAX_LENGTH);
                w8001->response_type = W8001_QUERY_PACKET;
                complete(&w8001->cmd_done);
                break;
        }

        return IRQ_HANDLED;
}

static int w8001_command(struct w8001 *w8001, unsigned char command,
                         bool wait_response)
{
        int rc;

        w8001->response_type = 0;
        init_completion(&w8001->cmd_done);

        rc = serio_write(w8001->serio, command);
        if (rc == 0 && wait_response) {

                wait_for_completion_timeout(&w8001->cmd_done, HZ);
                if (w8001->response_type != W8001_QUERY_PACKET)
                        rc = -EIO;
        }

        return rc;
}

static int w8001_setup(struct w8001 *w8001)
{
        struct input_dev *dev = w8001->dev;
        struct w8001_coord coord;
        int error;

        error = w8001_command(w8001, W8001_CMD_QUERY, true);
        if (error)
                return error;

        parse_data(w8001->response, &coord);

        input_set_abs_params(dev, ABS_X, 0, coord.x, 0, 0);
        input_set_abs_params(dev, ABS_Y, 0, coord.y, 0, 0);
        input_set_abs_params(dev, ABS_PRESSURE, 0, coord.pen_pressure, 0, 0);
        input_set_abs_params(dev, ABS_TILT_X, 0, coord.tilt_x, 0, 0);
        input_set_abs_params(dev, ABS_TILT_Y, 0, coord.tilt_y, 0, 0);

        return w8001_command(w8001, W8001_CMD_START, false);
}

/*
 * w8001_disconnect() is the opposite of w8001_connect()
 */

static void w8001_disconnect(struct serio *serio)
{
        struct w8001 *w8001 = serio_get_drvdata(serio);

        input_get_device(w8001->dev);
        input_unregister_device(w8001->dev);
        serio_close(serio);
        serio_set_drvdata(serio, NULL);
        input_put_device(w8001->dev);
        kfree(w8001);
}

/*
 * w8001_connect() is the routine that is called when someone adds a
 * new serio device that supports the w8001 protocol and registers it as
 * an input device.
 */

static int w8001_connect(struct serio *serio, struct serio_driver *drv)
{
        struct w8001 *w8001;
        struct input_dev *input_dev;
        int err;

        w8001 = kzalloc(sizeof(struct w8001), GFP_KERNEL);
        input_dev = input_allocate_device();
        if (!w8001 || !input_dev) {
                err = -ENOMEM;
                goto fail1;
        }

        w8001->serio = serio;
        w8001->id = serio->id.id;
        w8001->dev = input_dev;
        init_completion(&w8001->cmd_done);
        snprintf(w8001->phys, sizeof(w8001->phys), "%s/input0", serio->phys);

        input_dev->name = "Wacom W8001 Penabled Serial TouchScreen";
        input_dev->phys = w8001->phys;
        input_dev->id.bustype = BUS_RS232;
        input_dev->id.vendor = SERIO_W8001;
        input_dev->id.product = w8001->id;
        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);

        serio_set_drvdata(serio, w8001);
        err = serio_open(serio, drv);
        if (err)
                goto fail2;

        err = w8001_setup(w8001);
        if (err)
                goto fail3;

        err = input_register_device(w8001->dev);
        if (err)
                goto fail3;

        return 0;

fail3:
        serio_close(serio);
fail2:
        serio_set_drvdata(serio, NULL);
fail1:
        input_free_device(input_dev);
        kfree(w8001);
        return err;
}

static struct serio_device_id w8001_serio_ids[] = {
        {
                .type   = SERIO_RS232,
                .proto  = SERIO_W8001,
                .id     = SERIO_ANY,
                .extra  = SERIO_ANY,
        },
        { 0 }
};

MODULE_DEVICE_TABLE(serio, w8001_serio_ids);

static struct serio_driver w8001_drv = {
        .driver         = {
                .name   = "w8001",
        },
        .description    = DRIVER_DESC,
        .id_table       = w8001_serio_ids,
        .interrupt      = w8001_interrupt,
        .connect        = w8001_connect,
        .disconnect     = w8001_disconnect,
};

static int __init w8001_init(void)
{
        return serio_register_driver(&w8001_drv);
}

static void __exit w8001_exit(void)
{
        serio_unregister_driver(&w8001_drv);
}

module_init(w8001_init);
module_exit(w8001_exit);