Message-ID: <20100210182024.GA29610@core.coreip.homeip.net>
Date:	Wed, 10 Feb 2010 10:20:24 -0800
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Michael Poole <mdpoole@...ilus.org>
Cc:	Jiri Kosina <jkosina@...e.cz>, linux-input@...r.kernel.org,
	Marcel Holtmann <marcel@...tmann.org>,
	linux-bluetooth@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] Add a device driver for the Apple Magic Mouse.

Hi Michael,

On Tue, Feb 09, 2010 at 08:13:08AM -0500, Michael Poole wrote:
> +
> +static bool emulate_3button = 1;

If it is a bool then values should be true/false.

> +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 = 1;
> +module_param(emulate_scroll_wheel, bool, 0644);
> +MODULE_PARM_DESC(emulate_scroll_wheel, "Emulate a scroll wheel");
> +
> +static bool report_touches = 1;
> +module_param(report_touches, bool, 0644);
> +MODULE_PARM_DESC(report_touches, "Emit touch records (otherwise, only use them for emulation)");
> +
> +static bool report_undeciphered = 0;

No need to initialize statics to 0/false.

> +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;

Indented with spaces, we prefer tabs.

> +
> +	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]);
> +		}

No need for braces for single statement.

> +
> +		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);

I'd use __set_bit() instead, no need to lock the bus.

> +
> +	if (report_touches) {
> +		set_bit(EV_ABS, input->evbit);
> +
> +		set_bit(ABS_MT_TRACKING_ID, input->absbit);
> +		input->absmin[ABS_MT_TRACKING_ID] = 0;
> +		input->absmax[ABS_MT_TRACKING_ID] = 15;
> +		input->absfuzz[ABS_MT_TRACKING_ID] = 0;

input_set_abs_params() is a bit more compact.

> +
> +		set_bit(ABS_MT_TOUCH_MAJOR, input->absbit);
> +		input->absmin[ABS_MT_TOUCH_MAJOR] = 0;
> +		input->absmax[ABS_MT_TOUCH_MAJOR] = 255;
> +		input->absfuzz[ABS_MT_TOUCH_MAJOR] = 4;
> +
> +		set_bit(ABS_MT_TOUCH_MINOR, input->absbit);
> +		input->absmin[ABS_MT_TOUCH_MINOR] = 0;
> +		input->absmax[ABS_MT_TOUCH_MINOR] = 255;
> +		input->absfuzz[ABS_MT_TOUCH_MINOR] = 4;
> +
> +		set_bit(ABS_MT_ORIENTATION, input->absbit);
> +		input->absmin[ABS_MT_ORIENTATION] = -32;
> +		input->absmax[ABS_MT_ORIENTATION] = 31;
> +		input->absfuzz[ABS_MT_ORIENTATION] = 1;
> +
> +		set_bit(ABS_MT_POSITION_X, input->absbit);
> +		input->absmin[ABS_MT_POSITION_X] = -1100;
> +		input->absmax[ABS_MT_POSITION_X] = 1358;
> +		input->absfuzz[ABS_MT_POSITION_X] = 4;
> +
> +		/* 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.
> +		 */
> +		set_bit(ABS_MT_POSITION_Y, input->absbit);
> +		input->absmin[ABS_MT_POSITION_Y] = -1589;
> +		input->absmax[ABS_MT_POSITION_Y] = 2047;
> +		input->absfuzz[ABS_MT_POSITION_Y] = 4;
> +	}
> +
> +	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;
> +	}
> +
> +	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_free;
> +	}
> +	report->size = 6;
> +
> +	ret = hdev->hid_output_raw_report(hdev, feature_1, sizeof(feature_1),
> +			HID_FEATURE_REPORT);

This will cause transmission of on-stack data through USB which it does
not like.

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

Same here.

> +	if (ret != sizeof(feature_2)) {
> +		dev_err(&hdev->dev, "unable to request touch data (2:%d)\n",
> +				ret);
> +		goto err_free;
> +	}
> +
> +	input = input_allocate_device();
> +	if (!input) {
> +		dev_err(&hdev->dev, "can't alloc input device\n");
> +		ret = -ENOMEM;
> +		goto err_free;
> +	}
> +	magicmouse_setup_input(input, hdev);
> +
> +	ret = input_register_device(input);
> +	if (ret) {
> +		dev_err(&hdev->dev, "input device registration failed\n");
> +		goto err_both;
> +	}
> +	msc->input = input;
> +
> +	return 0;
> + err_both:
> +	input_free_device(input);
> + err_free:
> +	kfree(msc);
> +	return ret;

hid_hw_stop() is missing in error path. Also see question about freeing
report below.

> +}
> +
> +static void magicmouse_remove(struct hid_device *hdev)
> +{

Do we need to unregister report (I am not that familiar with HID, who is
responsible for cleaning report lists?)?

> +	hid_hw_stop(hdev);
> +	kfree(hid_get_drvdata(hdev));
> +}
> +
> +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");
> -- 
> 1.6.5.6
> 
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-- 
Dmitry
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