/*
 * 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(sizeof(*w8001), GFP_KERNEL);
	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);