/*
 *  HID driver for 3M PCT multitouch panels
 *
 *  Copyright (c) 2009 Stephane Chatty <chatty@enac.fr>
 *
 */

/*
 * 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.
 */

#include <linux/device.h>
#include <linux/hid.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/usb.h>

MODULE_AUTHOR("Stephane Chatty <chatty@enac.fr>");
MODULE_DESCRIPTION("3M PCT multitouch panels");
MODULE_LICENSE("GPL");

#include "hid-ids.h"

struct mmm_finger {
	__s32 x, y;
	__u8 rank;
	bool touch, valid;
};

struct mmm_data {
	struct mmm_finger f[10];
	__u8 curid, num;
	bool touch, valid;
};

static int mmm_input_mapping(struct hid_device *hdev, struct hid_input *hi,
		struct hid_field *field, struct hid_usage *usage,
		unsigned long **bit, int *max)
{
	switch (usage->hid & HID_USAGE_PAGE) {

	case HID_UP_BUTTON:
		return -1;

	case HID_UP_GENDESK:
		switch (usage->hid) {
		case HID_GD_X:
			hid_map_usage(hi, usage, bit, max,
					EV_ABS, ABS_MT_POSITION_X);
			/* touchscreen emulation */
			input_set_abs_params(hi->input, ABS_X,
						field->logical_minimum,
						field->logical_maximum, 0, 0);
			return 1;
		case HID_GD_Y:
			hid_map_usage(hi, usage, bit, max,
					EV_ABS, ABS_MT_POSITION_Y);
			/* touchscreen emulation */
			input_set_abs_params(hi->input, ABS_Y,
						field->logical_minimum,
						field->logical_maximum, 0, 0);
			return 1;
		}
		return 0;

	case HID_UP_DIGITIZER:
		switch (usage->hid) {
		/* we do not want to map these: no input-oriented meaning */
		case 0x14:
		case 0x23:
		case HID_DG_INPUTMODE:
		case HID_DG_DEVICEINDEX:
		case HID_DG_CONTACTCOUNT:
		case HID_DG_CONTACTMAX:
		case HID_DG_INRANGE:
		case HID_DG_CONFIDENCE:
			return -1;
		case HID_DG_TIPSWITCH:
			/* touchscreen emulation */
			hid_map_usage(hi, usage, bit, max, EV_KEY, BTN_TOUCH);
			return 1;
		case HID_DG_CONTACTID:
			hid_map_usage(hi, usage, bit, max,
					EV_ABS, ABS_MT_TRACKING_ID);
			return 1;
		}
		/* let hid-input decide for the others */
		return 0;

	case 0xff000000:
		/* we do not want to map these: no input-oriented meaning */
		return -1;
	}

	return 0;
}

static int mmm_input_mapped(struct hid_device *hdev, struct hid_input *hi,
		struct hid_field *field, struct hid_usage *usage,
		unsigned long **bit, int *max)
{
	if (usage->type == EV_KEY || usage->type == EV_ABS)
		clear_bit(usage->code, *bit);

	return 0;
}

/*
 * this function is called when a whole packet has been received and processed,
 * so that it can decide what to send to the input layer.
 */
static void mmm_filter_event(struct mmm_data *md, struct input_dev *input)
{
	struct mmm_finger *oldest = 0;
	bool pressed = false, released = false;
	int i;

	/*
	 * we need to iterate on all fingers to decide if we have a press
	 * or a release event in our touchscreen emulation.
	 */
	for (i = 0; i < 10; ++i) {
		struct mmm_finger *f = &md->f[i];
		if (!f->valid) {
			/* this finger is just placeholder data, ignore */
		} else if (f->touch) {
			/* this finger is on the screen */
			input_event(input, EV_ABS, ABS_MT_TRACKING_ID, i);
			input_event(input, EV_ABS, ABS_MT_POSITION_X, f->x);
			input_event(input, EV_ABS, ABS_MT_POSITION_Y, f->y);
			input_mt_sync(input);
			/*
			 * touchscreen emulation: maintain the age rank
			 * of this finger, decide if we have a press
			 */
			if (f->rank == 0) {
				f->rank = ++(md->num);
				if (f->rank == 1)
					pressed = true;
			}
			if (f->rank == 1)
				oldest = f;
		} else {
			/* this finger took off the screen */
			/* touchscreen emulation: maintain age rank of others */
			int j;

			for (j = 0; j < 10; ++j) {
				struct mmm_finger *g = &md->f[j];
				if (g->rank > f->rank) {
					g->rank--;
					if (g->rank == 1)
						oldest = g;
				}
			}
			f->rank = 0;
			--(md->num);
			if (md->num == 0)
				released = true;
		}
		f->valid = 0;
	}

	/* touchscreen emulation */
	if (oldest) {
		if (pressed)
			input_event(input, EV_KEY, BTN_TOUCH, 1);
		input_event(input, EV_ABS, ABS_X, oldest->x);
		input_event(input, EV_ABS, ABS_Y, oldest->y);
	} else if (released) {
		input_event(input, EV_KEY, BTN_TOUCH, 0);
	}
}

/*
 * this function is called upon all reports
 * so that we can accumulate contact point information,
 * and call input_mt_sync after each point.
 */
static int mmm_event(struct hid_device *hid, struct hid_field *field,
				struct hid_usage *usage, __s32 value)
{
	struct mmm_data *md = hid_get_drvdata(hid);
	/*
	 * strangely, this function can be called before
	 * field->hidinput is initialized!
	 */
	if (hid->claimed & HID_CLAIMED_INPUT) {
		struct input_dev *input = field->hidinput->input;
		switch (usage->hid) {
		case HID_DG_TIPSWITCH:
			md->touch = value;
			break;
		case HID_DG_CONFIDENCE:
			md->valid = value;
			break;
		case HID_DG_CONTACTID:
			if (md->valid) {
				md->curid = value;
				md->f[value].touch = md->touch;
				md->f[value].valid = 1;
			}
			break;
		case HID_GD_X:
			if (md->valid)
				md->f[md->curid].x = value;
			break;
		case HID_GD_Y:
			if (md->valid)
				md->f[md->curid].y = value;
			break;
		case HID_DG_CONTACTCOUNT:
			mmm_filter_event(md, input);
			break;
		}
	}

	/* we have handled the hidinput part, now remains hiddev */
	if (hid->claimed & HID_CLAIMED_HIDDEV && hid->hiddev_hid_event)
		hid->hiddev_hid_event(hid, field, usage, value);

	return 1;
}

static int mmm_probe(struct hid_device *hdev, const struct hid_device_id *id)
{
	int ret;
	struct mmm_data *md;

	md = kzalloc(sizeof(struct mmm_data), GFP_KERNEL);
	if (!md) {
		dev_err(&hdev->dev, "cannot allocate 3M data\n");
		return -ENOMEM;
	}
	hid_set_drvdata(hdev, md);

	ret = hid_parse(hdev);
	if (!ret)
		ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);

	if (ret)
		kfree(md);
	return ret;
}

static void mmm_remove(struct hid_device *hdev)
{
	hid_hw_stop(hdev);
	kfree(hid_get_drvdata(hdev));
	hid_set_drvdata(hdev, NULL);
}

static const struct hid_device_id mmm_devices[] = {
	{ HID_USB_DEVICE(USB_VENDOR_ID_3M, USB_DEVICE_ID_3M1968) },
	{ }
};
MODULE_DEVICE_TABLE(hid, mmm_devices);

static const struct hid_usage_id mmm_grabbed_usages[] = {
	{ HID_ANY_ID, HID_ANY_ID, HID_ANY_ID },
	{ HID_ANY_ID - 1, HID_ANY_ID - 1, HID_ANY_ID - 1}
};

static struct hid_driver mmm_driver = {
	.name = "3m-pct",
	.id_table = mmm_devices,
	.probe = mmm_probe,
	.remove = mmm_remove,
	.input_mapping = mmm_input_mapping,
	.input_mapped = mmm_input_mapped,
	.usage_table = mmm_grabbed_usages,
	.event = mmm_event,
};

static int __init mmm_init(void)
{
	return hid_register_driver(&mmm_driver);
}

static void __exit mmm_exit(void)
{
	hid_unregister_driver(&mmm_driver);
}

module_init(mmm_init);
module_exit(mmm_exit);
MODULE_LICENSE("GPL");