[PATCH] hid: 3m: Convert to MT slots (rev2)

["Henrik Rydberg" <rydberg@euromail.se>]

The Microtouch controller is capable of doing finger tracking on
up to 60 fingers. To reduce bandwidth and cpu usage, convert the
driver to use the MT slots protocol. On Stephane's suggestion, also
insert the additional copyright lines.

Acked-by: Stephane Chatty <chatty@enac.fr>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
---
This is the second revision of the patch, containing these changes:
     - Added copyright lines
     - Added comment for signal-to-noise rations
     - Added Stephanes ACK (correctly spelled :-))

Cheers,
Henrik

 drivers/hid/hid-3m-pct.c |   54 ++++++++++++++++++++++++++++++++++++---------
 1 files changed, 43 insertions(+), 11 deletions(-)

diff --git a/drivers/hid/hid-3m-pct.c b/drivers/hid/hid-3m-pct.c
index 1057430..d0e03f3 100644
--- a/drivers/hid/hid-3m-pct.c
+++ b/drivers/hid/hid-3m-pct.c
@@ -2,6 +2,8 @@
  *  HID driver for 3M PCT multitouch panels
  *
  *  Copyright (c) 2009-2010 Stephane Chatty <chatty@enac.fr>
+ *  Copyright (c) 2010      Henrik Rydberg <rydberg@euromail.se>
+ *  Copyright (c) 2010      Canonical, Ltd.
  *
  */
 
@@ -25,16 +27,24 @@ MODULE_LICENSE("GPL");
 #include "hid-ids.h"
 
 #define MAX_SLOTS		60
-#define MAX_TRKID		59
+#define MAX_TRKID		USHRT_MAX
+#define MAX_EVENTS		360
+
+/* estimated signal-to-noise ratios */
+#define SN_MOVE			2048
+#define SN_WIDTH		128
 
 struct mmm_finger {
 	__s32 x, y, w, h;
+	__u16 id;
 	__u8 rank;
+	bool prev_touch;
 	bool touch, valid;
 };
 
 struct mmm_data {
 	struct mmm_finger f[MAX_SLOTS];
+	__u16 id;
 	__u8 curid, num;
 	__u8 nexp, nreal;
 	bool touch, valid;
@@ -44,6 +54,10 @@ 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)
 {
+	int f1 = field->logical_minimum;
+	int f2 = field->logical_maximum;
+	int df = f2 - f1;
+
 	switch (usage->hid & HID_USAGE_PAGE) {
 
 	case HID_UP_BUTTON:
@@ -54,18 +68,20 @@ static int mmm_input_mapping(struct hid_device *hdev, struct hid_input *hi,
 		case HID_GD_X:
 			hid_map_usage(hi, usage, bit, max,
 					EV_ABS, ABS_MT_POSITION_X);
+			input_set_abs_params(hi->input, ABS_MT_POSITION_X,
+					     f1, f2, df / SN_MOVE, 0);
 			/* touchscreen emulation */
 			input_set_abs_params(hi->input, ABS_X,
-						field->logical_minimum,
-						field->logical_maximum, 0, 0);
+					     f1, f2, df / SN_MOVE, 0);
 			return 1;
 		case HID_GD_Y:
 			hid_map_usage(hi, usage, bit, max,
 					EV_ABS, ABS_MT_POSITION_Y);
+			input_set_abs_params(hi->input, ABS_MT_POSITION_Y,
+					     f1, f2, df / SN_MOVE, 0);
 			/* touchscreen emulation */
 			input_set_abs_params(hi->input, ABS_Y,
-						field->logical_minimum,
-						field->logical_maximum, 0, 0);
+					     f1, f2, df / SN_MOVE, 0);
 			return 1;
 		}
 		return 0;
@@ -85,14 +101,19 @@ static int mmm_input_mapping(struct hid_device *hdev, struct hid_input *hi,
 		case HID_DG_TIPSWITCH:
 			/* touchscreen emulation */
 			hid_map_usage(hi, usage, bit, max, EV_KEY, BTN_TOUCH);
+			input_set_capability(hi->input, EV_KEY, BTN_TOUCH);
 			return 1;
 		case HID_DG_WIDTH:
 			hid_map_usage(hi, usage, bit, max,
 					EV_ABS, ABS_MT_TOUCH_MAJOR);
+			input_set_abs_params(hi->input, ABS_MT_TOUCH_MAJOR,
+					     f1, f2, df / SN_WIDTH, 0);
 			return 1;
 		case HID_DG_HEIGHT:
 			hid_map_usage(hi, usage, bit, max,
 					EV_ABS, ABS_MT_TOUCH_MINOR);
+			input_set_abs_params(hi->input, ABS_MT_TOUCH_MINOR,
+					     f1, f2, df / SN_WIDTH, 0);
 			input_set_abs_params(hi->input, ABS_MT_ORIENTATION,
 					1, 1, 0, 0);
 			return 1;
@@ -100,6 +121,11 @@ static int mmm_input_mapping(struct hid_device *hdev, struct hid_input *hi,
 			field->logical_maximum = MAX_TRKID;
 			hid_map_usage(hi, usage, bit, max,
 					EV_ABS, ABS_MT_TRACKING_ID);
+			input_set_abs_params(hi->input, ABS_MT_TRACKING_ID,
+					     0, MAX_TRKID, 0, 0);
+			if (!hi->input->mt)
+				input_mt_create_slots(hi->input, MAX_SLOTS);
+			input_set_events_per_packet(hi->input, MAX_EVENTS);
 			return 1;
 		}
 		/* let hid-input decide for the others */
@@ -117,10 +143,10 @@ 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)
 {
+	/* tell hid-input to skip setup of these event types */
 	if (usage->type == EV_KEY || usage->type == EV_ABS)
-		clear_bit(usage->code, *bit);
-
-	return 0;
+		set_bit(usage->type, hi->input->evbit);
+	return -1;
 }
 
 /*
@@ -141,10 +167,15 @@ static void mmm_filter_event(struct mmm_data *md, struct input_dev *input)
 		struct mmm_finger *f = &md->f[i];
 		if (!f->valid) {
 			/* this finger is just placeholder data, ignore */
-		} else if (f->touch) {
+			continue;
+		}
+		input_mt_slot(input, i);
+		if (f->touch) {
 			/* this finger is on the screen */
 			int wide = (f->w > f->h);
-			input_event(input, EV_ABS, ABS_MT_TRACKING_ID, i);
+			if (!f->prev_touch)
+				f->id = md->id++;
+			input_event(input, EV_ABS, ABS_MT_TRACKING_ID, f->id);
 			input_event(input, EV_ABS, ABS_MT_POSITION_X, f->x);
 			input_event(input, EV_ABS, ABS_MT_POSITION_Y, f->y);
 			input_event(input, EV_ABS, ABS_MT_ORIENTATION, wide);
@@ -152,7 +183,6 @@ static void mmm_filter_event(struct mmm_data *md, struct input_dev *input)
 						wide ? f->w : f->h);
 			input_event(input, EV_ABS, ABS_MT_TOUCH_MINOR,
 						wide ? f->h : f->w);
-			input_mt_sync(input);
 			/*
 			 * touchscreen emulation: maintain the age rank
 			 * of this finger, decide if we have a press
@@ -181,7 +211,9 @@ static void mmm_filter_event(struct mmm_data *md, struct input_dev *input)
 			--(md->num);
 			if (md->num == 0)
 				released = true;
+			input_event(input, EV_ABS, ABS_MT_TRACKING_ID, -1);
 		}
+		f->prev_touch = f->touch;
 		f->valid = 0;
 	}
 
-- 
1.7.1