/*
 * Wacom W8001 penabled serial touchscreen driver
 *
 * Copyright (c) 2008 Jaya Kumar
 * Copyright (c) 2010 Red Hat, Inc.
 * Copyright (c) 2010 - 2011 Ping Cheng, Wacom. <pingc@wacom.com>
 *
 * 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/mt.h>
#include <linux/serio.h>
#include <linux/ctype.h>
#include <linux/delay.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_PHYS          42

#define W8001_MAX_LENGTH        13
#define W8001_LEAD_MASK         0x80
#define W8001_LEAD_BYTE         0x80
#define W8001_TAB_MASK          0x40
#define W8001_TAB_BYTE          0x40
/* set in first byte of touch data packets */
#define W8001_TOUCH_MASK        (0x10 | W8001_LEAD_MASK)
#define W8001_TOUCH_BYTE        (0x10 | W8001_LEAD_BYTE)

#define W8001_QUERY_PACKET      0x20

#define W8001_CMD_STOP          '0'
#define W8001_CMD_START         '1'
#define W8001_CMD_QUERY         '*'
#define W8001_CMD_TOUCHQUERY    '%'

/* length of data packets in bytes, depends on device. */
#define W8001_PKTLEN_TOUCH93    5
#define W8001_PKTLEN_TOUCH9A    7
#define W8001_PKTLEN_TPCPEN     9
#define W8001_PKTLEN_TPCCTL     11      /* control packet */
#define W8001_PKTLEN_TOUCH2FG   13

/* resolution in points/mm */
#define W8001_PEN_RESOLUTION    100
#define W8001_TOUCH_RESOLUTION  10

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

/* touch query reply packet */
struct w8001_touch_query {
        u16 x;
        u16 y;
        u8 panel_res;
        u8 capacity_res;
        u8 sensor_id;
};

/*
 * Per-touchscreen data.
 */

struct w8001 {
        struct input_dev *pen_dev;
        struct input_dev *touch_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[W8001_MAX_PHYS];
        int type;
        unsigned int pktlen;
        u16 max_touch_x;
        u16 max_touch_y;
        u16 max_pen_x;
        u16 max_pen_y;
        char pen_name[64];
        char touch_name[64];
        int open_count;
        struct mutex mutex;
};

static void parse_pen_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 void parse_single_touch(u8 *data, struct w8001_coord *coord)
{
        coord->x = (data[1] << 7) | data[2];
        coord->y = (data[3] << 7) | data[4];
        coord->tsw = data[0] & 0x01;
}

static void scale_touch_coordinates(struct w8001 *w8001,
                                    unsigned int *x, unsigned int *y)
{
        if (w8001->max_pen_x && w8001->max_touch_x)
                *x = *x * w8001->max_pen_x / w8001->max_touch_x;

        if (w8001->max_pen_y && w8001->max_touch_y)
                *y = *y * w8001->max_pen_y / w8001->max_touch_y;
}

static void parse_multi_touch(struct w8001 *w8001)
{
        struct input_dev *dev = w8001->touch_dev;
        unsigned char *data = w8001->data;
        unsigned int x, y;
        int i;
        int count = 0;

        for (i = 0; i < 2; i++) {
                bool touch = data[0] & (1 << i);

                input_mt_slot(dev, i);
                input_mt_report_slot_state(dev, MT_TOOL_FINGER, touch);
                if (touch) {
                        x = (data[6 * i + 1] << 7) | data[6 * i + 2];
                        y = (data[6 * i + 3] << 7) | data[6 * i + 4];
                        /* data[5,6] and [11,12] is finger capacity */

                        /* scale to pen maximum */
                        scale_touch_coordinates(w8001, &x, &y);

                        input_report_abs(dev, ABS_MT_POSITION_X, x);
                        input_report_abs(dev, ABS_MT_POSITION_Y, y);
                        count++;
                }
        }

        /* emulate single touch events when stylus is out of proximity.
         * This is to make single touch backward support consistent
         * across all Wacom single touch devices.
         */
        if (w8001->type != BTN_TOOL_PEN &&
                            w8001->type != BTN_TOOL_RUBBER) {
                w8001->type = count == 1 ? BTN_TOOL_FINGER : KEY_RESERVED;
                input_mt_report_pointer_emulation(dev, true);
        }

        input_sync(dev);
}

static void parse_touchquery(u8 *data, struct w8001_touch_query *query)
{
        memset(query, 0, sizeof(*query));

        query->panel_res = data[1];
        query->sensor_id = data[2] & 0x7;
        query->capacity_res = data[7];

        query->x = data[3] << 9;
        query->x |= data[4] << 2;
        query->x |= (data[2] >> 5) & 0x3;

        query->y = data[5] << 9;
        query->y |= data[6] << 2;
        query->y |= (data[2] >> 3) & 0x3;

        /* Early days' single-finger touch models need the following defaults */
        if (!query->x && !query->y) {
                query->x = 1024;
                query->y = 1024;
                if (query->panel_res)
                        query->x = query->y = (1 << query->panel_res);
                query->panel_res = W8001_TOUCH_RESOLUTION;
        }
}

static void report_pen_events(struct w8001 *w8001, struct w8001_coord *coord)
{
        struct input_dev *dev = w8001->pen_dev;

        /*
         * We have 1 bit for proximity (rdy) and 3 bits for tip, side,
         * side2/eraser. If rdy && f2 are set, this can be either pen + side2,
         * or eraser. Assume:
         * - if dev is already in proximity and f2 is toggled → pen + side2
         * - if dev comes into proximity with f2 set → eraser
         * If f2 disappears after assuming eraser, fake proximity out for
         * eraser and in for pen.
         */

        switch (w8001->type) {
        case BTN_TOOL_RUBBER:
                if (!coord->f2) {
                        input_report_abs(dev, ABS_PRESSURE, 0);
                        input_report_key(dev, BTN_TOUCH, 0);
                        input_report_key(dev, BTN_STYLUS, 0);
                        input_report_key(dev, BTN_STYLUS2, 0);
                        input_report_key(dev, BTN_TOOL_RUBBER, 0);
                        input_sync(dev);
                        w8001->type = BTN_TOOL_PEN;
                }
                break;

        case BTN_TOOL_FINGER:
        case KEY_RESERVED:
                w8001->type = coord->f2 ? BTN_TOOL_RUBBER : BTN_TOOL_PEN;
                break;

        default:
                input_report_key(dev, BTN_STYLUS2, coord->f2);
                break;
        }

        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_report_key(dev, BTN_STYLUS, coord->f1);
        input_report_key(dev, w8001->type, coord->rdy);
        input_sync(dev);

        if (!coord->rdy)
                w8001->type = KEY_RESERVED;
}

static void report_single_touch(struct w8001 *w8001, struct w8001_coord *coord)
{
        struct input_dev *dev = w8001->touch_dev;
        unsigned int x = coord->x;
        unsigned int y = coord->y;

        /* scale to pen maximum */
        scale_touch_coordinates(w8001, &x, &y);

        input_report_abs(dev, ABS_X, x);
        input_report_abs(dev, ABS_Y, y);
        input_report_key(dev, BTN_TOUCH, coord->tsw);

        input_sync(dev);

        w8001->type = coord->tsw ? BTN_TOOL_FINGER : KEY_RESERVED;
}

static irqreturn_t w8001_interrupt(struct serio *serio,
                                   unsigned char data, unsigned int flags)
{
        struct w8001 *w8001 = serio_get_drvdata(serio);
        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 W8001_PKTLEN_TOUCH93 - 1:
        case W8001_PKTLEN_TOUCH9A - 1:
                tmp = w8001->data[0] & W8001_TOUCH_BYTE;
                if (tmp != W8001_TOUCH_BYTE)
                        break;

                if (w8001->pktlen == w8001->idx) {
                        w8001->idx = 0;
                        if (w8001->type != BTN_TOOL_PEN &&
                            w8001->type != BTN_TOOL_RUBBER) {
                                parse_single_touch(w8001->data, &coord);
                                report_single_touch(w8001, &coord);
                        }
                }
                break;

        /* Pen coordinates packet */
        case W8001_PKTLEN_TPCPEN - 1:
                tmp = w8001->data[0] & W8001_TAB_MASK;
                if (unlikely(tmp == W8001_TAB_BYTE))
                        break;

                tmp = w8001->data[0] & W8001_TOUCH_BYTE;
                if (tmp == W8001_TOUCH_BYTE)
                        break;

                w8001->idx = 0;
                parse_pen_data(w8001->data, &coord);
                report_pen_events(w8001, &coord);
                break;

        /* control packet */
        case W8001_PKTLEN_TPCCTL - 1:
                tmp = w8001->data[0] & W8001_TOUCH_MASK;
                if (tmp == W8001_TOUCH_BYTE)
                        break;

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

        /* 2 finger touch packet */
        case W8001_PKTLEN_TOUCH2FG - 1:
                w8001->idx = 0;
                parse_multi_touch(w8001);
                break;

        default:
                /*
                 * ThinkPad X60 Tablet PC (pen only device) sometimes
                 * sends invalid data packets that are larger than
                 * W8001_PKTLEN_TPCPEN. Let's start over again.
                 */
                if (!w8001->touch_dev && w8001->idx > W8001_PKTLEN_TPCPEN - 1)
                        w8001->idx = 0;
        }

        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_open(struct input_dev *dev)
{
        struct w8001 *w8001 = input_get_drvdata(dev);
        int err;

        scoped_guard(mutex_intr, &w8001->mutex) {
                if (w8001->open_count == 0) {
                        err = w8001_command(w8001, W8001_CMD_START, false);
                        if (err)
                                return err;
                }

                w8001->open_count++;
                return 0;
        }

        return -EINTR;
}

static void w8001_close(struct input_dev *dev)
{
        struct w8001 *w8001 = input_get_drvdata(dev);

        guard(mutex)(&w8001->mutex);

        if (--w8001->open_count == 0)
                w8001_command(w8001, W8001_CMD_STOP, false);
}

static int w8001_detect(struct w8001 *w8001)
{
        int error;

        error = w8001_command(w8001, W8001_CMD_STOP, false);
        if (error)
                return error;

        msleep(250);    /* wait 250ms before querying the device */

        return 0;
}

static int w8001_setup_pen(struct w8001 *w8001, char *basename,
                           size_t basename_sz)
{
        struct input_dev *dev = w8001->pen_dev;
        struct w8001_coord coord;
        int error;

        /* penabled? */
        error = w8001_command(w8001, W8001_CMD_QUERY, true);
        if (error)
                return error;

        __set_bit(EV_KEY, dev->evbit);
        __set_bit(EV_ABS, dev->evbit);
        __set_bit(BTN_TOUCH, dev->keybit);
        __set_bit(BTN_TOOL_PEN, dev->keybit);
        __set_bit(BTN_TOOL_RUBBER, dev->keybit);
        __set_bit(BTN_STYLUS, dev->keybit);
        __set_bit(BTN_STYLUS2, dev->keybit);
        __set_bit(INPUT_PROP_DIRECT, dev->propbit);

        parse_pen_data(w8001->response, &coord);
        w8001->max_pen_x = coord.x;
        w8001->max_pen_y = coord.y;

        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_abs_set_res(dev, ABS_X, W8001_PEN_RESOLUTION);
        input_abs_set_res(dev, ABS_Y, W8001_PEN_RESOLUTION);
        input_set_abs_params(dev, ABS_PRESSURE, 0, coord.pen_pressure, 0, 0);
        if (coord.tilt_x && coord.tilt_y) {
                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);
        }

        w8001->id = 0x90;
        strlcat(basename, " Penabled", basename_sz);

        return 0;
}

static int w8001_setup_touch(struct w8001 *w8001, char *basename,
                             size_t basename_sz)
{
        struct input_dev *dev = w8001->touch_dev;
        struct w8001_touch_query touch;
        int error;


        /* Touch enabled? */
        error = w8001_command(w8001, W8001_CMD_TOUCHQUERY, true);
        if (error)
                return error;
        /*
         * Some non-touch devices may reply to the touch query. But their
         * second byte is empty, which indicates touch is not supported.
         */
        if (!w8001->response[1])
                return -ENXIO;

        __set_bit(EV_KEY, dev->evbit);
        __set_bit(EV_ABS, dev->evbit);
        __set_bit(BTN_TOUCH, dev->keybit);
        __set_bit(INPUT_PROP_DIRECT, dev->propbit);

        parse_touchquery(w8001->response, &touch);
        w8001->max_touch_x = touch.x;
        w8001->max_touch_y = touch.y;

        if (w8001->max_pen_x && w8001->max_pen_y) {
                /* if pen is supported scale to pen maximum */
                touch.x = w8001->max_pen_x;
                touch.y = w8001->max_pen_y;
                touch.panel_res = W8001_PEN_RESOLUTION;
        }

        input_set_abs_params(dev, ABS_X, 0, touch.x, 0, 0);
        input_set_abs_params(dev, ABS_Y, 0, touch.y, 0, 0);
        input_abs_set_res(dev, ABS_X, touch.panel_res);
        input_abs_set_res(dev, ABS_Y, touch.panel_res);

        switch (touch.sensor_id) {
        case 0:
        case 2:
                w8001->pktlen = W8001_PKTLEN_TOUCH93;
                w8001->id = 0x93;
                strlcat(basename, " 1FG", basename_sz);
                break;

        case 1:
        case 3:
        case 4:
                w8001->pktlen = W8001_PKTLEN_TOUCH9A;
                strlcat(basename, " 1FG", basename_sz);
                w8001->id = 0x9a;
                break;

        case 5:
                w8001->pktlen = W8001_PKTLEN_TOUCH2FG;

                __set_bit(BTN_TOOL_DOUBLETAP, dev->keybit);
                error = input_mt_init_slots(dev, 2, 0);
                if (error) {
                        dev_err(&w8001->serio->dev,
                                "failed to initialize MT slots: %d\n", error);
                        return error;
                }

                input_set_abs_params(dev, ABS_MT_POSITION_X,
                                        0, touch.x, 0, 0);
                input_set_abs_params(dev, ABS_MT_POSITION_Y,
                                        0, touch.y, 0, 0);
                input_set_abs_params(dev, ABS_MT_TOOL_TYPE,
                                        0, MT_TOOL_MAX, 0, 0);
                input_abs_set_res(dev, ABS_MT_POSITION_X, touch.panel_res);
                input_abs_set_res(dev, ABS_MT_POSITION_Y, touch.panel_res);

                strlcat(basename, " 2FG", basename_sz);
                if (w8001->max_pen_x && w8001->max_pen_y)
                        w8001->id = 0xE3;
                else
                        w8001->id = 0xE2;
                break;
        }

        strlcat(basename, " Touchscreen", basename_sz);

        return 0;
}

static void w8001_set_devdata(struct input_dev *dev, struct w8001 *w8001,
                              struct serio *serio)
{
        dev->phys = w8001->phys;
        dev->id.bustype = BUS_RS232;
        dev->id.product = w8001->id;
        dev->id.vendor = 0x056a;
        dev->id.version = 0x0100;
        dev->open = w8001_open;
        dev->close = w8001_close;

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

        input_set_drvdata(dev, w8001);
}

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

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

        serio_close(serio);

        if (w8001->pen_dev)
                input_unregister_device(w8001->pen_dev);
        if (w8001->touch_dev)
                input_unregister_device(w8001->touch_dev);
        kfree(w8001);

        serio_set_drvdata(serio, NULL);
}

/*
 * 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_pen;
        struct input_dev *input_dev_touch;
        char basename[64] = "Wacom Serial";
        int err, err_pen, err_touch;

        w8001 = kzalloc_obj(*w8001);
        input_dev_pen = input_allocate_device();
        input_dev_touch = input_allocate_device();
        if (!w8001 || !input_dev_pen || !input_dev_touch) {
                err = -ENOMEM;
                goto fail1;
        }

        w8001->serio = serio;
        w8001->pen_dev = input_dev_pen;
        w8001->touch_dev = input_dev_touch;
        mutex_init(&w8001->mutex);
        init_completion(&w8001->cmd_done);
        snprintf(w8001->phys, sizeof(w8001->phys), "%s/input0", serio->phys);

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

        err = w8001_detect(w8001);
        if (err)
                goto fail3;

        /* For backwards-compatibility we compose the basename based on
         * capabilities and then just append the tool type
         */
        err_pen = w8001_setup_pen(w8001, basename, sizeof(basename));
        err_touch = w8001_setup_touch(w8001, basename, sizeof(basename));
        if (err_pen && err_touch) {
                err = -ENXIO;
                goto fail3;
        }

        if (!err_pen) {
                snprintf(w8001->pen_name, sizeof(w8001->pen_name),
                         "%s Pen", basename);
                input_dev_pen->name = w8001->pen_name;

                w8001_set_devdata(input_dev_pen, w8001, serio);

                err = input_register_device(w8001->pen_dev);
                if (err)
                        goto fail3;
        } else {
                input_free_device(input_dev_pen);
                input_dev_pen = NULL;
                w8001->pen_dev = NULL;
        }

        if (!err_touch) {
                snprintf(w8001->touch_name, sizeof(w8001->touch_name),
                         "%s Finger", basename);
                input_dev_touch->name = w8001->touch_name;

                w8001_set_devdata(input_dev_touch, w8001, serio);

                err = input_register_device(w8001->touch_dev);
                if (err)
                        goto fail4;
        } else {
                input_free_device(input_dev_touch);
                input_dev_touch = NULL;
                w8001->touch_dev = NULL;
        }

        return 0;

fail4:
        if (w8001->pen_dev)
                input_unregister_device(w8001->pen_dev);
fail3:
        serio_close(serio);
fail2:
        serio_set_drvdata(serio, NULL);
fail1:
        input_free_device(input_dev_pen);
        input_free_device(input_dev_touch);
        kfree(w8001);
        return err;
}

static const 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,
};

module_serio_driver(w8001_drv);