/*
 *   Apple "Magic" Wireless Mouse driver
 *
 *   Copyright (c) 2010 Michael Poole <mdpoole@troilus.org>
 */

/*
 * 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>

#include "hid-ids.h"

static bool emulate_3button = true;
module_param(emulate_3button, bool, 0644);
MODULE_PARM_DESC(emulate_3button, "Emulate a middle button");

static int middle_button_start = -350;
static int middle_button_stop = +350;

static bool emulate_scroll_wheel = true;
module_param(emulate_scroll_wheel, bool, 0644);
MODULE_PARM_DESC(emulate_scroll_wheel, "Emulate a scroll wheel");

static bool report_touches = true;
module_param(report_touches, bool, 0644);
MODULE_PARM_DESC(report_touches, "Emit touch records (otherwise, only use them for emulation)");

static bool report_undeciphered;
module_param(report_undeciphered, bool, 0644);
MODULE_PARM_DESC(report_undeciphered, "Report undeciphered multi-touch state field using a MSC_RAW event");

#define TOUCH_REPORT_ID   0x29
/* These definitions are not precise, but they're close enough.  (Bits
 * 0x03 seem to indicate the aspect ratio of the touch, bits 0x70 seem
 * to be some kind of bit mask -- 0x20 may be a near-field reading,
 * and 0x40 is actual contact, and 0x10 may be a start/stop or change
 * indication.)
 */
#define TOUCH_STATE_MASK  0xf0
#define TOUCH_STATE_NONE  0x00
#define TOUCH_STATE_START 0x30
#define TOUCH_STATE_DRAG  0x40

/**
 * struct magicmouse_sc - Tracks Magic Mouse-specific data.
 * @input: Input device through which we report events.
 * @quirks: Currently unused.
 * @last_timestamp: Timestamp from most recent (18-bit) touch report
 *     (units of milliseconds over short windows, but seems to
 *     increase faster when there are no touches).
 * @delta_time: 18-bit difference between the two most recent touch
 *     reports from the mouse.
 * @ntouches: Number of touches in most recent touch report.
 * @scroll_accel: Number of consecutive scroll motions.
 * @scroll_jiffies: Time of last scroll motion.
 * @touches: Most recent data for a touch, indexed by tracking ID.
 * @tracking_ids: Mapping of current touch input data to @touches.
 */
struct magicmouse_sc {
	struct input_dev *input;
	unsigned long quirks;

	int last_timestamp;
	int delta_time;
	int ntouches;
	int scroll_accel;
	unsigned long scroll_jiffies;

	struct {
		short x;
		short y;
		short scroll_y;
		u8 size;
	} touches[16];
	int tracking_ids[16];
};

static int magicmouse_firm_touch(struct magicmouse_sc *msc)
{
	int touch = -1;
	int ii;

	/* If there is only one "firm" touch, set touch to its
	 * tracking ID.
	 */
	for (ii = 0; ii < msc->ntouches; ii++) {
		int idx = msc->tracking_ids[ii];
		if (msc->touches[idx].size < 8) {
			/* Ignore this touch. */
		} else if (touch >= 0) {
			touch = -1;
			break;
		} else {
			touch = idx;
		}
	}

	return touch;
}

static void magicmouse_emit_buttons(struct magicmouse_sc *msc, int state)
{
	int last_state = test_bit(BTN_LEFT, msc->input->key) << 0 |
		test_bit(BTN_RIGHT, msc->input->key) << 1 |
		test_bit(BTN_MIDDLE, msc->input->key) << 2;

	if (emulate_3button) {
		int id;

		/* If some button was pressed before, keep it held
		 * down.  Otherwise, if there's exactly one firm
		 * touch, use that to override the mouse's guess.
		 */
		if (state == 0) {
			/* The button was released. */
		} else if (last_state != 0) {
			state = last_state;
		} else if ((id = magicmouse_firm_touch(msc)) >= 0) {
			int x = msc->touches[id].x;
			if (x < middle_button_start)
				state = 1;
			else if (x > middle_button_stop)
				state = 2;
			else
				state = 4;
		} /* else: we keep the mouse's guess */

		input_report_key(msc->input, BTN_MIDDLE, state & 4);
	}

	input_report_key(msc->input, BTN_LEFT, state & 1);
	input_report_key(msc->input, BTN_RIGHT, state & 2);

	if (state != last_state)
		msc->scroll_accel = 0;
}

static void magicmouse_emit_touch(struct magicmouse_sc *msc, int raw_id, u8 *tdata)
{
	struct input_dev *input = msc->input;
	__s32 x_y = tdata[0] << 8 | tdata[1] << 16 | tdata[2] << 24;
	int misc = tdata[5] | tdata[6] << 8;
	int id = (misc >> 6) & 15;
	int x = x_y << 12 >> 20;
	int y = -(x_y >> 20);

	/* Store tracking ID and other fields. */
	msc->tracking_ids[raw_id] = id;
	msc->touches[id].x = x;
	msc->touches[id].y = y;
	msc->touches[id].size = misc & 63;

	/* If requested, emulate a scroll wheel by detecting small
	 * vertical touch motions along the middle of the mouse.
	 */
	if (emulate_scroll_wheel &&
	    middle_button_start < x && x < middle_button_stop) {
		static const int accel_profile[] = {
			256, 228, 192, 160, 128, 96, 64, 32,
		};
		unsigned long now = jiffies;
		int step = msc->touches[id].scroll_y - y;

		/* Reset acceleration after half a second. */
		if (time_after(now, msc->scroll_jiffies + HZ / 2))
			msc->scroll_accel = 0;

		/* Calculate and apply the scroll motion. */
		switch (tdata[7] & TOUCH_STATE_MASK) {
		case TOUCH_STATE_START:
			msc->touches[id].scroll_y = y;
			msc->scroll_accel = min_t(int, msc->scroll_accel + 1,
						ARRAY_SIZE(accel_profile) - 1);
			break;
		case TOUCH_STATE_DRAG:
			step = step / accel_profile[msc->scroll_accel];
			if (step != 0) {
				msc->touches[id].scroll_y = y;
				msc->scroll_jiffies = now;
				input_report_rel(input, REL_WHEEL, step);
			}
			break;
		}
	}

	/* Generate the input events for this touch. */
	if (report_touches) {
		int orientation = (misc >> 10) - 32;

		input_report_abs(input, ABS_MT_TRACKING_ID, id);
		input_report_abs(input, ABS_MT_TOUCH_MAJOR, tdata[3]);
		input_report_abs(input, ABS_MT_TOUCH_MINOR, tdata[4]);
		input_report_abs(input, ABS_MT_ORIENTATION, orientation);
		input_report_abs(input, ABS_MT_POSITION_X, x);
		input_report_abs(input, ABS_MT_POSITION_Y, y);

		if (report_undeciphered)
			input_event(input, EV_MSC, MSC_RAW, tdata[7]);

		input_mt_sync(input);
	}
}

static int magicmouse_raw_event(struct hid_device *hdev,
		struct hid_report *report, u8 *data, int size)
{
	struct magicmouse_sc *msc = hid_get_drvdata(hdev);
	struct input_dev *input = msc->input;
	int x, y, ts, ii, clicks;

	switch (data[0]) {
	case 0x10:
		if (size != 6)
			return 0;
		x = (__s16)(data[2] | data[3] << 8);
		y = (__s16)(data[4] | data[5] << 8);
		clicks = data[1];
		break;
	case TOUCH_REPORT_ID:
		/* Expect six bytes of prefix, and N*8 bytes of touch data. */
		if (size < 6 || ((size - 6) % 8) != 0)
			return 0;
		ts = data[3] >> 6 | data[4] << 2 | data[5] << 10;
		msc->delta_time = (ts - msc->last_timestamp) & 0x3ffff;
		msc->last_timestamp = ts;
		msc->ntouches = (size - 6) / 8;
		for (ii = 0; ii < msc->ntouches; ii++)
			magicmouse_emit_touch(msc, ii, data + ii * 8 + 6);
		/* When emulating three-button mode, it is important
		 * to have the current touch information before
		 * generating a click event.
		 */
		x = (signed char)data[1];
		y = (signed char)data[2];
		clicks = data[3];
		break;
	case 0x20: /* Theoretically battery status (0-100), but I have
		    * never seen it -- maybe it is only upon request.
		    */
	case 0x60: /* Unknown, maybe laser on/off. */
	case 0x61: /* Laser reflection status change.
		    * data[1]: 0 = spotted, 1 = lost
		    */
	default:
		return 0;
	}

	magicmouse_emit_buttons(msc, clicks & 3);
	input_report_rel(input, REL_X, x);
	input_report_rel(input, REL_Y, y);
	input_sync(input);
	return 1;
}

static int magicmouse_input_open(struct input_dev *dev)
{
	struct hid_device *hid = input_get_drvdata(dev);

	return hid->ll_driver->open(hid);
}

static void magicmouse_input_close(struct input_dev *dev)
{
	struct hid_device *hid = input_get_drvdata(dev);

	hid->ll_driver->close(hid);
}

static void magicmouse_setup_input(struct input_dev *input, struct hid_device *hdev)
{
	input_set_drvdata(input, hdev);
	input->event = hdev->ll_driver->hidinput_input_event;
	input->open = magicmouse_input_open;
	input->close = magicmouse_input_close;

	input->name = hdev->name;
	input->phys = hdev->phys;
	input->uniq = hdev->uniq;
	input->id.bustype = hdev->bus;
	input->id.vendor = hdev->vendor;
	input->id.product = hdev->product;
	input->id.version = hdev->version;
	input->dev.parent = hdev->dev.parent;

	__set_bit(EV_KEY, input->evbit);
	__set_bit(BTN_LEFT, input->keybit);
	__set_bit(BTN_RIGHT, input->keybit);
	if (emulate_3button)
		__set_bit(BTN_MIDDLE, input->keybit);
	__set_bit(BTN_TOOL_FINGER, input->keybit);

	__set_bit(EV_REL, input->evbit);
	__set_bit(REL_X, input->relbit);
	__set_bit(REL_Y, input->relbit);
	if (emulate_scroll_wheel)
		__set_bit(REL_WHEEL, input->relbit);

	if (report_touches) {
		__set_bit(EV_ABS, input->evbit);

		input_set_abs_params(input, ABS_MT_TRACKING_ID, 0, 15, 0, 0);
		input_set_abs_params(input, ABS_MT_TOUCH_MAJOR, 0, 255, 4, 0);
		input_set_abs_params(input, ABS_MT_TOUCH_MINOR, 0, 255, 4, 0);
		input_set_abs_params(input, ABS_MT_ORIENTATION, -32, 31, 1, 0);
		input_set_abs_params(input, ABS_MT_POSITION_X, -1100, 1358,
				4, 0);
		/* Note: Touch Y position from the device is inverted relative
		 * to how pointer motion is reported (and relative to how USB
		 * HID recommends the coordinates work).  This driver keeps
		 * the origin at the same position, and just uses the additive
		 * inverse of the reported Y.
		 */
		input_set_abs_params(input, ABS_MT_POSITION_Y, -1589, 2047,
				4, 0);
	}

	if (report_undeciphered) {
		__set_bit(EV_MSC, input->evbit);
		__set_bit(MSC_RAW, input->mscbit);
	}
}

static int magicmouse_probe(struct hid_device *hdev,
	const struct hid_device_id *id)
{
	__u8 feature_1[] = { 0xd7, 0x01 };
	__u8 feature_2[] = { 0xf8, 0x01, 0x32 };
	struct input_dev *input;
	struct magicmouse_sc *msc;
	struct hid_report *report;
	int ret;

	msc = kzalloc(sizeof(*msc), GFP_KERNEL);
	if (msc == NULL) {
		dev_err(&hdev->dev, "can't alloc magicmouse descriptor\n");
		return -ENOMEM;
	}

	msc->quirks = id->driver_data;
	hid_set_drvdata(hdev, msc);

	ret = hid_parse(hdev);
	if (ret) {
		dev_err(&hdev->dev, "magicmouse hid parse failed\n");
		goto err_free;
	}

	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
	if (ret) {
		dev_err(&hdev->dev, "magicmouse hw start failed\n");
		goto err_free;
	}

	/* we are handling the input ourselves */
	hidinput_disconnect(hdev);

	report = hid_register_report(hdev, HID_INPUT_REPORT, TOUCH_REPORT_ID);
	if (!report) {
		dev_err(&hdev->dev, "unable to register touch report\n");
		ret = -ENOMEM;
		goto err_stop_hw;
	}
	report->size = 6;

	ret = hdev->hid_output_raw_report(hdev, feature_1, sizeof(feature_1),
			HID_FEATURE_REPORT);
	if (ret != sizeof(feature_1)) {
		dev_err(&hdev->dev, "unable to request touch data (1:%d)\n",
				ret);
		goto err_stop_hw;
	}
	ret = hdev->hid_output_raw_report(hdev, feature_2,
			sizeof(feature_2), HID_FEATURE_REPORT);
	if (ret != sizeof(feature_2)) {
		dev_err(&hdev->dev, "unable to request touch data (2:%d)\n",
				ret);
		goto err_stop_hw;
	}

	input = input_allocate_device();
	if (!input) {
		dev_err(&hdev->dev, "can't alloc input device\n");
		ret = -ENOMEM;
		goto err_stop_hw;
	}
	magicmouse_setup_input(input, hdev);

	ret = input_register_device(input);
	if (ret) {
		dev_err(&hdev->dev, "input device registration failed\n");
		goto err_input;
	}
	msc->input = input;

	return 0;
err_input:
	input_free_device(input);
err_stop_hw:
	hid_hw_stop(hdev);
err_free:
	kfree(msc);
	return ret;
}

static void magicmouse_remove(struct hid_device *hdev)
{
	struct magicmouse_sc *msc = hid_get_drvdata(hdev);

	hid_hw_stop(hdev);
	input_unregister_device(msc->input);
	kfree(msc);
}

static const struct hid_device_id magic_mice[] = {
	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_MAGICMOUSE),
		.driver_data = 0 },
	{ }
};
MODULE_DEVICE_TABLE(hid, magic_mice);

static struct hid_driver magicmouse_driver = {
	.name = "magicmouse",
	.id_table = magic_mice,
	.probe = magicmouse_probe,
	.remove = magicmouse_remove,
	.raw_event = magicmouse_raw_event,
};

static int __init magicmouse_init(void)
{
	int ret;

	ret = hid_register_driver(&magicmouse_driver);
	if (ret)
		printk(KERN_ERR "can't register magicmouse driver\n");

	return ret;
}

static void __exit magicmouse_exit(void)
{
	hid_unregister_driver(&magicmouse_driver);
}

module_init(magicmouse_init);
module_exit(magicmouse_exit);
MODULE_LICENSE("GPL");