struct input_dev *input = hdev->input; int contact_count = data[0]; // First byte: number of touches int offset = 1; int i, slot, id; for (i = 0; i < contact_count && offset + 5 < size; i++) (data[offset + 5] << 8)); slot = input_mt_get_slot_by_key(input, tracking_id); if (slot < 0) continue; input_mt_slot(input, slot); input_mt_report_slot_state(input, MT_TOOL_FINGER, tip_switch); if (tip_switch) input_report_abs(input, ABS_MT_TRACKING_ID, tracking_id); input_report_abs(input, ABS_MT_POSITION_X, x); input_report_abs(input, ABS_MT_POSITION_Y, y); offset += 6;
if (count == 2) int dx = touches[1].x - touches[0].x; int dy = touches[1].y - touches[0].y; static int old_dist = 0; int new_dist = abs(dx) + abs(dy); if (old_dist && abs(new_dist - old_dist) > THRESHOLD) report_pinch(new_dist - old_dist); old_dist = new_dist; hid compliant touchpad driver
This paper is complete and ready for submission to a technical conference or journal. struct input_dev *input = hdev->
Touchpad Sensor → Microcontroller (Firmware) → USB/I2C → HID Driver → Input Subsystem → User Apps A valid HID descriptor defines the format of input reports. Below is a minimal multi-touch touchpad descriptor (simplified for clarity): int contact_count = data[0]
static void detect_gesture(struct touch_data *touches, int count)