Date:	Wed, 01 Sep 2010 00:00:15 +0200
From:	Henrik Rydberg <rydberg@...omail.se>
To:	Chase Douglas <chase.douglas@...onical.com>
CC:	Jiri Kosina <jkosina@...e.cz>, Michael Poole <mdpoole@...ilus.org>,
	Tejun Heo <tj@...nel.org>, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/6 v2] HID: magicmouse: enable Magic Trackpad support

On 08/31/2010 08:41 PM, Chase Douglas wrote:

> The trackpad speaks a similar, but different, protocol from the magic
> mouse. However, only small code tweaks here and there are needed to make
> basic multitouch work.
> 
> Extra logic is required for single-touch emulation of the touchpad. The
> changes made here take the approach that only one finger may emulate the
> single pointer when multiple fingers have touched the screen. Once that
> finger is raised, all touches must be raised before any further single
> touch events can be sent.
> 
> Sometimes the magic trackpad sends two distinct touch reports as one big
> report. Simply splitting the packet in two and resending them through
> magicmouse_raw_event ensures they are handled properly.
> 
> I also added myself to the copyright statement.
> 
> Signed-off-by: Chase Douglas <chase.douglas@...onical.com>


Thanks for this driver. Comments inline.

[...]

> @@ -166,15 +170,29 @@ static void magicmouse_emit_buttons(struct magicmouse_sc *msc, int state)
>  static void magicmouse_emit_touch(struct magicmouse_sc *msc, int raw_id, u8 *tdata)
>  {
>  	struct input_dev *input = msc->input;
> -	int id = (tdata[6] << 2 | tdata[5] >> 6) & 0xf;
> -	int x = (tdata[1] << 28 | tdata[0] << 20) >> 20;
> -	int y = -((tdata[2] << 24 | tdata[1] << 16) >> 20);
> -	int size = tdata[5] & 0x3f;
> -	int orientation = (tdata[6] >> 2) - 32;
> -	int touch_major = tdata[3];
> -	int touch_minor = tdata[4];
> -	int state = tdata[7] & TOUCH_STATE_MASK;
> -	int down = state != TOUCH_STATE_NONE;
> +	int id, x, y, size, orientation, touch_major, touch_minor, state, down;
> +
> +	if (input->id.product == USB_DEVICE_ID_APPLE_MAGICMOUSE) {
> +		id = (tdata[6] << 2 | tdata[5] >> 6) & 0xf;
> +		x = (tdata[1] << 28 | tdata[0] << 20) >> 20;
> +		y = -((tdata[2] << 24 | tdata[1] << 16) >> 20);
> +		size = tdata[5] & 0x3f;
> +		orientation = (tdata[6] >> 2) - 32;
> +		touch_major = tdata[3];
> +		touch_minor = tdata[4];
> +		state = tdata[7] & TOUCH_STATE_MASK;
> +		down = state != TOUCH_STATE_NONE;
> +	} else { /* USB_DEVICE_ID_APPLE_MAGICTRACKPAD */
> +		id = (tdata[7] << 2 | tdata[6] >> 6) & 0xf;
> +		x = (tdata[1] << 27 | tdata[0] << 19) >> 19;
> +		y = -((tdata[3] << 30 | tdata[2] << 22 | tdata[1] << 14) >> 19);
> +		size = tdata[6] & 0x3f;
> +		orientation = (tdata[7] >> 2) - 32;
> +		touch_major = tdata[4];
> +		touch_minor = tdata[5];
> +		state = tdata[8] & TOUCH_STATE_MASK;
> +		down = state != TOUCH_STATE_NONE;
> +	}
>  
>  	/* Store tracking ID and other fields. */
>  	msc->tracking_ids[raw_id] = id;
> @@ -225,10 +243,15 @@ static void magicmouse_emit_touch(struct magicmouse_sc *msc, int raw_id, u8 *tda
>  		}
>  	}
>  
> -	/* Generate the input events for this touch. */
> -	if (report_touches && down) {
> +	if (down) {
>  		msc->touches[id].down = 1;
> +		if (msc->single_touch_id == -1)
> +			msc->single_touch_id = id;
> +	} else if (msc->single_touch_id == id)
> +		msc->single_touch_id = -2;


The logic using single_touch_id seems complicated. Any chance you could get by
with less code here?


> +	/* Generate the input events for this touch. */
> +	if (report_touches && down) {
>  		input_report_abs(input, ABS_MT_TRACKING_ID, id);


The tracking id reported by the macpad is not ideal; it works more like a slot
that a MT protocol tracking id. Perhaps it is a slot? I would recommend looking
at the recent submissions for bamboo touch, 3m-pct and w8001 to see how the
tracking id and slots could be handled.

>  		input_report_abs(input, ABS_MT_TOUCH_MAJOR, touch_major);
>  		input_report_abs(input, ABS_MT_TOUCH_MINOR, touch_minor);
> @@ -236,8 +259,12 @@ static void magicmouse_emit_touch(struct magicmouse_sc *msc, int raw_id, u8 *tda
>  		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]);
> +		if (report_undeciphered) {
> +			if (input->id.product == USB_DEVICE_ID_APPLE_MAGICMOUSE)
> +				input_event(input, EV_MSC, MSC_RAW, tdata[7]);
> +			else /* USB_DEVICE_ID_APPLE_MAGICTRACKPAD */
> +				input_event(input, EV_MSC, MSC_RAW, tdata[8]);
> +		}
>  
>  		input_mt_sync(input);
>  	}
> @@ -248,7 +275,7 @@ static int magicmouse_raw_event(struct hid_device *hdev,
>  {
>  	struct magicmouse_sc *msc = hid_get_drvdata(hdev);
>  	struct input_dev *input = msc->input;
> -	int x, y, ts, ii, clicks, last_up;
> +	int x = 0, y = 0, ts, ii, clicks = 0, last_up;
>  
>  	switch (data[0]) {
>  	case 0x10:
> @@ -258,7 +285,19 @@ static int magicmouse_raw_event(struct hid_device *hdev,
>  		y = (__s16)(data[4] | data[5] << 8);
>  		clicks = data[1];
>  		break;
> -	case TOUCH_REPORT_ID:
> +	case TRACKPAD_REPORT_ID:
> +		/* Expect four bytes of prefix, and N*9 bytes of touch data. */
> +		if (size < 4 || ((size - 4) % 9) != 0)
> +			return 0;
> +		ts = data[1] >> 6 | data[2] << 2 | data[3] << 10;
> +		msc->delta_time = (ts - msc->last_timestamp) & 0x3ffff;
> +		msc->last_timestamp = ts;


The delta_time and last_timestamp do not seem to be used anywhere?

> +		msc->ntouches = (size - 4) / 9;
> +		for (ii = 0; ii < msc->ntouches; ii++)
> +			magicmouse_emit_touch(msc, ii, data + ii * 9 + 4);
> +		clicks = data[1];
> +		break;
> +	case MOUSE_REPORT_ID:
>  		/* Expect six bytes of prefix, and N*8 bytes of touch data. */
>  		if (size < 6 || ((size - 6) % 8) != 0)
>  			return 0;
> @@ -269,19 +308,6 @@ static int magicmouse_raw_event(struct hid_device *hdev,
>  		for (ii = 0; ii < msc->ntouches; ii++)
>  			magicmouse_emit_touch(msc, ii, data + ii * 8 + 6);
>  
> -		if (report_touches) {
> -			last_up = 1;
> -			for (ii = 0; ii < ARRAY_SIZE(msc->touches); ii++) {
> -				if (msc->touches[ii].down) {
> -					last_up = 0;
> -					msc->touches[ii].down = 0;
> -				}
> -			}
> -			if (last_up) {
> -				input_mt_sync(input);
> -			}
> -		}
> -
>  		/* When emulating three-button mode, it is important
>  		 * to have the current touch information before
>  		 * generating a click event.
> @@ -290,6 +316,14 @@ static int magicmouse_raw_event(struct hid_device *hdev,
>  		y = (int)(((data[3] & 0x30) << 26) | (data[2] << 22)) >> 22;
>  		clicks = data[3];
>  		break;
> +	case DOUBLE_REPORT_ID:
> +		/* Sometimes the trackpad sends two touch reports in one
> +		 * packet.
> +		 */
> +		magicmouse_raw_event(hdev, report, data + 2, data[1]);
> +		magicmouse_raw_event(hdev, report, data + 2 + data[1],
> +			size - 2 - data[1]);
> +		break;


Nice find.

>  	case 0x20: /* Theoretically battery status (0-100), but I have
>  		    * never seen it -- maybe it is only upon request.
>  		    */
> @@ -301,9 +335,41 @@ static int magicmouse_raw_event(struct hid_device *hdev,
>  		return 0;
>  	}
>  
> -	magicmouse_emit_buttons(msc, clicks & 3);
> -	input_report_rel(input, REL_X, x);
> -	input_report_rel(input, REL_Y, y);
> +	if ((data[0] == MOUSE_REPORT_ID || data[0] == TRACKPAD_REPORT_ID)) {
> +		last_up = 1;
> +		for (ii = 0; ii < ARRAY_SIZE(msc->touches); ii++) {
> +			if (msc->touches[ii].down) {
> +				last_up = 0;
> +				msc->touches[ii].down = 0;
> +			}
> +		}
> +		if (last_up) {
> +			msc->single_touch_id = -1;
> +			msc->ntouches = 0;
> +			if (report_touches)
> +				input_mt_sync(input);
> +		}


If the pointer emulation was handled differently, and the above was replaced
with something like

   if (!msc->ntouches)
  	input_mt_sync(input);

it would be short enough not to need to be broken out of the switch... Besides,
BTN_TOUCH is emitted for the trackpad case, so the above code is not strictly
needed.

> +	}
> +
> +	if (input->id.product == USB_DEVICE_ID_APPLE_MAGICMOUSE) {
> +		magicmouse_emit_buttons(msc, clicks & 3);
> +		input_report_rel(input, REL_X, x);
> +		input_report_rel(input, REL_Y, y);
> +	} else { /* USB_DEVICE_ID_APPLE_MAGICTRACKPAD */
> +		input_report_key(input, BTN_MOUSE, clicks & 1);
> +		input_report_key(input, BTN_TOUCH, msc->ntouches > 0);
> +		input_report_key(input, BTN_TOOL_FINGER, msc->ntouches == 1);
> +		input_report_key(input, BTN_TOOL_DOUBLETAP, msc->ntouches == 2);
> +		input_report_key(input, BTN_TOOL_TRIPLETAP, msc->ntouches == 3);
> +		input_report_key(input, BTN_TOOL_QUADTAP, msc->ntouches == 4);
> +		if (msc->single_touch_id >= 0) {
> +			input_report_abs(input, ABS_X,
> +				msc->touches[msc->single_touch_id].x);
> +			input_report_abs(input, ABS_Y,
> +				msc->touches[msc->single_touch_id].y);
> +		}
> +	}
> +
>  	input_sync(input);
>  	return 1;
>  }
> @@ -339,18 +405,27 @@ static void magicmouse_setup_input(struct input_dev *input, struct hid_device *h
>  	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);
> -		__set_bit(REL_HWHEEL, input->relbit);
> +
> +	if (input->id.product == USB_DEVICE_ID_APPLE_MAGICMOUSE) {
> +		__set_bit(BTN_LEFT, input->keybit);
> +		__set_bit(BTN_RIGHT, input->keybit);
> +		if (emulate_3button)
> +			__set_bit(BTN_MIDDLE, 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);
> +			__set_bit(REL_HWHEEL, input->relbit);
> +		}
> +	} else { /* USB_DEVICE_ID_APPLE_MAGICTRACKPAD */
> +		__set_bit(BTN_MOUSE, input->keybit);
> +		__set_bit(BTN_TOOL_FINGER, input->keybit);
> +		__set_bit(BTN_TOOL_DOUBLETAP, input->keybit);
> +		__set_bit(BTN_TOOL_TRIPLETAP, input->keybit);
> +		__set_bit(BTN_TOOL_QUADTAP, input->keybit);
> +		__set_bit(BTN_TOUCH, input->keybit);
>  	}
>  
>  	if (report_touches) {
> @@ -360,16 +435,26 @@ static void magicmouse_setup_input(struct input_dev *input, struct hid_device *h
>  		input_set_abs_params(input, ABS_MT_TOUCH_MAJOR, 0, 255, 0, 0);
>  		input_set_abs_params(input, ABS_MT_TOUCH_MINOR, 0, 255, 0, 0);
>  		input_set_abs_params(input, ABS_MT_ORIENTATION, -32, 31, 0, 0);
> -		input_set_abs_params(input, ABS_MT_POSITION_X, -1100, 1358,
> -				0, 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,
> -				0, 0);
> +		if (input->id.product == USB_DEVICE_ID_APPLE_MAGICMOUSE) {
> +			input_set_abs_params(input, ABS_MT_POSITION_X, -1100,
> +				1358, 0, 0);
> +			input_set_abs_params(input, ABS_MT_POSITION_Y, -1589,
> +				2047, 0, 0);
> +		} else { /* USB_DEVICE_ID_APPLE_MAGICTRACKPAD */
> +			input_set_abs_params(input, ABS_X, -2909, 3167, 0, 0);
> +			input_set_abs_params(input, ABS_Y, -2456, 2565, 0, 0);
> +			input_set_abs_params(input, ABS_MT_POSITION_X, -2909,
> +				3167, 0, 0);
> +			input_set_abs_params(input, ABS_MT_POSITION_Y, -2456,
> +				2565, 0, 0);
> +		}
>  	}
>  
>  	if (report_undeciphered) {
> @@ -388,12 +473,29 @@ static struct feature mouse_features[] = {
>  	{ { 0xf8, 0x01, 0x32 }, 3 }
>  };
>  
> +static struct feature trackpad_features[] = {
> +	{ { 0xf1, 0xdb }, 2 },
> +	{ { 0xf1, 0xdc }, 2 },
> +	{ { 0xf0, 0x00 }, 2 },
> +	{ { 0xf1, 0xdd }, 2 },
> +	{ { 0xf0, 0x02 }, 2 },
> +	{ { 0xf1, 0xc8 }, 2 },
> +	{ { 0xf0, 0x09 }, 2 },
> +	{ { 0xf1, 0xdc }, 2 },
> +	{ { 0xf0, 0x00 }, 2 },
> +	{ { 0xf1, 0xdd }, 2 },
> +	{ { 0xf0, 0x02 }, 2 },
> +	{ { 0xd7, 0x01 }, 2 },
> +};


As noted by Michael, this could likely be simplified. the "0x01" on the last
line could be the same coding as wellspring mode for bcm5974.

Thanks,
Henrik
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