/*
 * Hampshire serial touchscreen driver
 *
 * Copyright (c) 2010 Adam Bennett
 * Based on the dynapro driver (c) Tias Guns
 *
 */

/*
 * 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.
 */

/*
 * 2010/04/08 Adam Bennett <abennett72@gmail.com>
 *   Copied dynapro.c and edited for Hampshire 4-byte 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     "Hampshire serial touchscreen driver"

MODULE_AUTHOR("Adam Bennett <abennett72@gmail.com>");
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");

/*
 * Definitions & global arrays.
 */

#define HAMPSHIRE_FORMAT_TOUCH_BIT 0x40
#define HAMPSHIRE_FORMAT_LENGTH 4
#define HAMPSHIRE_RESPONSE_BEGIN_BYTE 0x80

#define HAMPSHIRE_MIN_XC 0
#define HAMPSHIRE_MAX_XC 0x1000
#define HAMPSHIRE_MIN_YC 0
#define HAMPSHIRE_MAX_YC 0x1000

#define HAMPSHIRE_GET_XC(data) (((data[3] & 0x0c) >> 2) | (data[1] << 2) | ((data[0] & 0x38) << 6))
#define HAMPSHIRE_GET_YC(data) ((data[3] & 0x03) | (data[2] << 2) | ((data[0] & 0x07) << 9))
#define HAMPSHIRE_GET_TOUCHED(data) (HAMPSHIRE_FORMAT_TOUCH_BIT & data[0])

/*
 * Per-touchscreen data.
 */

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

static void hampshire_process_data(struct hampshire *phampshire)
{
        struct input_dev *dev = phampshire->dev;

        if (HAMPSHIRE_FORMAT_LENGTH == ++phampshire->idx) {
                input_report_abs(dev, ABS_X, HAMPSHIRE_GET_XC(phampshire->data));
                input_report_abs(dev, ABS_Y, HAMPSHIRE_GET_YC(phampshire->data));
                input_report_key(dev, BTN_TOUCH,
                                 HAMPSHIRE_GET_TOUCHED(phampshire->data));
                input_sync(dev);

                phampshire->idx = 0;
        }
}

static irqreturn_t hampshire_interrupt(struct serio *serio,
                unsigned char data, unsigned int flags)
{
        struct hampshire *phampshire = serio_get_drvdata(serio);

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

        if (HAMPSHIRE_RESPONSE_BEGIN_BYTE & phampshire->data[0])
                hampshire_process_data(phampshire);
        else
                dev_dbg(&serio->dev, "unknown/unsynchronized data: %x\n",
                        phampshire->data[0]);

        return IRQ_HANDLED;
}

static void hampshire_disconnect(struct serio *serio)
{
        struct hampshire *phampshire = serio_get_drvdata(serio);

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

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

static int hampshire_connect(struct serio *serio, struct serio_driver *drv)
{
        struct hampshire *phampshire;
        struct input_dev *input_dev;
        int err;

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

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

        input_dev->name = "Hampshire Serial TouchScreen";
        input_dev->phys = phampshire->phys;
        input_dev->id.bustype = BUS_RS232;
        input_dev->id.vendor = SERIO_HAMPSHIRE;
        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(phampshire->dev, ABS_X,
                             HAMPSHIRE_MIN_XC, HAMPSHIRE_MAX_XC, 0, 0);
        input_set_abs_params(phampshire->dev, ABS_Y,
                             HAMPSHIRE_MIN_YC, HAMPSHIRE_MAX_YC, 0, 0);

        serio_set_drvdata(serio, phampshire);

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

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

        return 0;

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

/*
 * The serio driver structure.
 */

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

MODULE_DEVICE_TABLE(serio, hampshire_serio_ids);

static struct serio_driver hampshire_drv = {
        .driver         = {
                .name   = "hampshire",
        },
        .description    = DRIVER_DESC,
        .id_table       = hampshire_serio_ids,
        .interrupt      = hampshire_interrupt,
        .connect        = hampshire_connect,
        .disconnect     = hampshire_disconnect,
};

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

static int __init hampshire_init(void)
{
        return serio_register_driver(&hampshire_drv);
}

static void __exit hampshire_exit(void)
{
        serio_unregister_driver(&hampshire_drv);
}

module_init(hampshire_init);
module_exit(hampshire_exit);