[PATCH v2 2/2] HID: wacom: Correct coordinate system of touchring and pen twist

[Jason Gerecke <killertofu@gmail.com>]

The MobileStudio Pro, Cintiq Pro, and 2nd-gen Intuos Pro devices use a
different coordinate system for their touchring and pen twist than prior
devices. Prior devices had zero aligned to the tablet's left and would
increase clockwise. Userspace expects data from the kernel to be in this
old coordinate space, so adjustments are necessary.

While the coordinate system for pen twist is formally defined by the HID
standard, no such definition existed for the touchring at the time these
tablets were introduced. Future tablets are expected to report touchring
data using the same "zero-up clockwise-increasing" coordinate system
defined for twist.

Fixes: 50066a042d ("HID: wacom: generic: Add support for height, tilt, and twist usages")
Fixes: 4922cd26f0 ("HID: wacom: Support 2nd-gen Intuos Pro's Bluetooth classic interface")
Fixes: 60a2218698 ("HID: wacom: generic: add support for touchring")
Cc: stable@vger.kernel.org # 4.10, 4.11
Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Reviewed-by: Ping Cheng <ping.cheng@wacom.com>
---
Changes from v1:
  * Applied fixes to bluetooth codepath as well

 drivers/hid/wacom_wac.c | 73 +++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 68 insertions(+), 5 deletions(-)

diff --git a/drivers/hid/wacom_wac.c b/drivers/hid/wacom_wac.c
index d7ca1eb9d559..d1bac66108e2 100644
--- a/drivers/hid/wacom_wac.c
+++ b/drivers/hid/wacom_wac.c
@@ -1227,11 +1227,17 @@ static void wacom_intuos_pro2_bt_pen(struct wacom_wac *wacom)
 			continue;
 
 		if (range) {
+			/* Fix rotation alignment: userspace expects zero at left */
+			int16_t rotation = (int16_t)get_unaligned_le16(&frame[9]);
+			rotation += 1800/4;
+			if (rotation > 899)
+				rotation -= 1800;
+
 			input_report_abs(pen_input, ABS_X, get_unaligned_le16(&frame[1]));
 			input_report_abs(pen_input, ABS_Y, get_unaligned_le16(&frame[3]));
 			input_report_abs(pen_input, ABS_TILT_X, (char)frame[7]);
 			input_report_abs(pen_input, ABS_TILT_Y, (char)frame[8]);
-			input_report_abs(pen_input, ABS_Z, (int16_t)get_unaligned_le16(&frame[9]));
+			input_report_abs(pen_input, ABS_Z, rotation);
 			input_report_abs(pen_input, ABS_WHEEL, get_unaligned_le16(&frame[11]));
 		}
 		input_report_abs(pen_input, ABS_PRESSURE, get_unaligned_le16(&frame[5]));
@@ -1319,12 +1325,19 @@ static void wacom_intuos_pro2_bt_pad(struct wacom_wac *wacom)
 	unsigned char *data = wacom->data;
 
 	int buttons = (data[282] << 1) | ((data[281] >> 6) & 0x01);
-	int ring = data[285];
-	int prox = buttons | (ring & 0x80);
+	int ring = data[285] & 0x7F;
+	bool ringstatus = data[285] & 0x80;
+	bool prox = buttons || ringstatus;
+
+	/* Fix touchring data: userspace expects 0 at left and increasing clockwise */
+	ring = 71 - ring;
+	ring += 3*72/16;
+	if (ring > 71)
+		ring -= 72;
 
 	wacom_report_numbered_buttons(pad_input, 9, buttons);
 
-	input_report_abs(pad_input, ABS_WHEEL, (ring & 0x80) ? (ring & 0x7f) : 0);
+	input_report_abs(pad_input, ABS_WHEEL, ringstatus ? ring : 0);
 
 	input_report_key(pad_input, wacom->tool[1], prox ? 1 : 0);
 	input_report_abs(pad_input, ABS_MISC, prox ? PAD_DEVICE_ID : 0);
@@ -1616,6 +1629,20 @@ static int wacom_tpc_irq(struct wacom_wac *wacom, size_t len)
 	return 0;
 }
 
+static int wacom_offset_rotation(struct input_dev *input, struct hid_usage *usage,
+				 int value, int num, int denom)
+{
+	struct input_absinfo *abs = &input->absinfo[usage->code];
+	int range = (abs->maximum - abs->minimum + 1);
+
+	value += num*range/denom;
+	if (value > abs->maximum)
+		value -= range;
+	else if (value < abs->minimum)
+		value += range;
+	return value;
+}
+
 int wacom_equivalent_usage(int usage)
 {
 	if ((usage & HID_USAGE_PAGE) == WACOM_HID_UP_WACOMDIGITIZER) {
@@ -1898,6 +1925,7 @@ static void wacom_wac_pad_event(struct hid_device *hdev, struct hid_field *field
 	unsigned equivalent_usage = wacom_equivalent_usage(usage->hid);
 	int i;
 	bool is_touch_on = value;
+	bool do_report = false;
 
 	/*
 	 * Avoid reporting this event and setting inrange_state if this usage
@@ -1912,6 +1940,29 @@ static void wacom_wac_pad_event(struct hid_device *hdev, struct hid_field *field
 	}
 
 	switch (equivalent_usage) {
+	case WACOM_HID_WD_TOUCHRING:
+		/*
+		 * Userspace expects touchrings to increase in value with
+		 * clockwise gestures and have their zero point at the
+		 * tablet's left. HID events "should" be clockwise-
+		 * increasing and zero at top, though the MobileStudio
+		 * Pro and 2nd-gen Intuos Pro don't do this...
+		 */
+		if (hdev->vendor == 0x56a &&
+		    (hdev->product == 0x34d || hdev->product == 0x34e ||  /* MobileStudio Pro */
+		     hdev->product == 0x357 || hdev->product == 0x358)) { /* Intuos Pro 2 */
+			value = (field->logical_maximum - value);
+
+			if (hdev->product == 0x357 || hdev->product == 0x358)
+				value = wacom_offset_rotation(input, usage, value, 3, 16);
+			else if (hdev->product == 0x34d || hdev->product == 0x34e)
+				value = wacom_offset_rotation(input, usage, value, 1, 2);
+		}
+		else {
+			value = wacom_offset_rotation(input, usage, value, 1, 4);
+		}
+		do_report = true;
+		break;
 	case WACOM_HID_WD_TOUCHRINGSTATUS:
 		if (!value)
 			input_event(input, usage->type, usage->code, 0);
@@ -1945,10 +1996,14 @@ static void wacom_wac_pad_event(struct hid_device *hdev, struct hid_field *field
 					 value, i);
 		 /* fall through*/
 	default:
+		do_report = true;
+		break;
+	}
+
+	if (do_report) {
 		input_event(input, usage->type, usage->code, value);
 		if (value)
 			wacom_wac->hid_data.pad_input_event_flag = true;
-		break;
 	}
 }
 
@@ -2089,6 +2144,14 @@ static void wacom_wac_pen_event(struct hid_device *hdev, struct hid_field *field
 		wacom_wac->serial[0] = (wacom_wac->serial[0] & ~0xFFFFFFFFULL);
 		wacom_wac->serial[0] |= (__u32)value;
 		return;
+	case HID_DG_TWIST:
+		/*
+		 * Userspace expects pen twist to have its zero point when
+		 * the buttons/finger is on the tablet's left. HID values
+		 * are zero when buttons are toward the top.
+		 */
+		value = wacom_offset_rotation(input, usage, value, 1, 4);
+		break;
 	case WACOM_HID_WD_SENSE:
 		wacom_wac->hid_data.sense_state = value;
 		return;
-- 
2.14.1