Apply fixes from kernel 5.15. Refers to #12.

README.md

@@ -1,11 +1,13 @@
 # Linux Apple Magic Mouse 2 and Magic Trackpad 2 Driver
 
-This repository contains the linux hid-magicmouse driver with Magic Trackpad 2 and Magic Mouse 2 support for Linux 4.18. For older kernels you might have to diff and backport. It also contains 2 fixes to the Magic Mouse 2 regarding Bluetooth random disconnections and this driver not loading on bluetooth reconnection.
+This repository contains the linux hid-magicmouse driver with Magic Trackpad 2 and Magic Mouse 2 support for Linux 4.18 onwards. For older kernels you might have to diff and backport. It also contains 2 fixes to the Magic Mouse 2 regarding Bluetooth random disconnections and this driver not loading on bluetooth reconnection.
 
 This driver is based off of the work of @robotrovsky, @svartalf, @0xABAD and probably others.
 
 Please help to test this driver and report issues.
 
+**NOTE**: Since kernel version 5.15, there is support for the mouse without the need for this driver. We try to backport changes to this driver to have it up-to-date with the one on the kernel and try to offer a bit more functionality but it is not perfect. If you want the mouse to just work either install a more recent kernel or proceed with this driver installation.
+
 ## Ubuntu (and derivatives)
 
 A `.deb` file is now available in Releases. Get the [latest version here](https://github.com/RicardoEPRodrigues/magicmouse-hid/releases/latest).

linux/drivers/hid/hid-magicmouse.c

@@ -106,6 +106,10 @@ MODULE_PARM_DESC(report_undeciphered, "Report undeciphered multi-touch state fie
 #define TOUCH_STATE_START 0x30
 #define TOUCH_STATE_DRAG  0x40
 
+/* Number of high-resolution events for each low-resolution detent. */
+#define SCROLL_HR_STEPS 10
+#define SCROLL_HR_MULT (120 / SCROLL_HR_STEPS)
+#define SCROLL_HR_THRESHOLD 90 /* units */
 #define SCROLL_ACCEL_DEFAULT 3
 
 /* Touch surface information. Dimension is in hundredths of a mm, min and max
@@ -169,7 +173,11 @@ struct magicmouse_sc {
 		short y;
 		short scroll_x;
 		short scroll_y;
+		short scroll_x_hr;
+		short scroll_y_hr;
 		u8 size;
+		bool scroll_x_active;
+		bool scroll_y_active;
 	} touches[MAX_TOUCHES];
 	int tracking_ids[MAX_TOUCHES];
 
@@ -346,6 +354,10 @@ static void magicmouse_emit_touch(struct magicmouse_sc *msc, int raw_id,
 		unsigned long now = jiffies;
 		int step_x = msc->touches[id].scroll_x - x;
 		int step_y = msc->touches[id].scroll_y - y;
+		int step_hr = ((64 - (int)scroll_speed) * msc->scroll_accel) /
+			      SCROLL_HR_STEPS;
+		int step_x_hr = msc->touches[id].scroll_x_hr - x;
+		int step_y_hr = msc->touches[id].scroll_y_hr - y;
 
 		/* Determine if the mouse has moved, if so then disable scrolling. */
 		bool continue_scroll = true;
@@ -360,6 +372,10 @@ static void magicmouse_emit_touch(struct magicmouse_sc *msc, int raw_id,
 			case TOUCH_STATE_START:
 				msc->touches[id].scroll_x = x;
 				msc->touches[id].scroll_y = y;
+				msc->touches[id].scroll_x_hr = x;
+				msc->touches[id].scroll_y_hr = y;
+				msc->touches[id].scroll_x_active = false;
+				msc->touches[id].scroll_y_active = false;
 
 				/* Reset acceleration after half a second. */
 				if (scroll_acceleration && time_before(now,
@@ -400,6 +416,40 @@ static void magicmouse_emit_touch(struct magicmouse_sc *msc, int raw_id,
 					msc->scroll_jiffies = now;
 					input_report_rel(input, REL_WHEEL, step_y);
 				}
+
+				if (!msc->touches[id].scroll_x_active &&
+					abs(step_x_hr) > SCROLL_HR_THRESHOLD) {
+					msc->touches[id].scroll_x_active = true;
+					msc->touches[id].scroll_x_hr = x;
+					step_x_hr = 0;
+				}
+
+				step_x_hr /= step_hr;
+				if (step_x_hr != 0 &&
+					msc->touches[id].scroll_x_active) {
+					msc->touches[id].scroll_x_hr -= step_x_hr *
+						step_hr;
+					input_report_rel(input,
+							REL_HWHEEL_HI_RES,
+							-step_x_hr * SCROLL_HR_MULT);
+				}
+
+				if (!msc->touches[id].scroll_y_active &&
+					abs(step_y_hr) > SCROLL_HR_THRESHOLD) {
+					msc->touches[id].scroll_y_active = true;
+					msc->touches[id].scroll_y_hr = y;
+					step_y_hr = 0;
+				}
+
+				step_y_hr /= step_hr;
+				if (step_y_hr != 0 &&
+					msc->touches[id].scroll_y_active) {
+					msc->touches[id].scroll_y_hr -= step_y_hr *
+						step_hr;
+					input_report_rel(input,
+							REL_WHEEL_HI_RES,
+							step_y_hr * SCROLL_HR_MULT);
+				}
 				break;
 			}
 		}
@@ -623,6 +673,8 @@ static int magicmouse_setup_input(struct input_dev *input, struct hid_device *hd
 		if (emulate_scroll_wheel) {
 			__set_bit(REL_WHEEL, input->relbit);
 			__set_bit(REL_HWHEEL, input->relbit);
+			__set_bit(REL_WHEEL_HI_RES, input->relbit);
+			__set_bit(REL_HWHEEL_HI_RES, input->relbit);
 		}
 	} else if (input->id.product == USB_DEVICE_ID_APPLE_MAGICTRACKPAD){
 		/* input->keybit is initialized with incorrect button info
@@ -835,7 +887,7 @@ static int magicmouse_probe(struct hid_device *hdev,
 	if (id->vendor == USB_VENDOR_ID_APPLE &&
 	    id->product == USB_DEVICE_ID_APPLE_MAGICTRACKPAD2 &&
 	    hdev->type != HID_TYPE_USBMOUSE)
-		return 0;
+		return -ENODEV;
 
 	msc = devm_kzalloc(&hdev->dev, sizeof(*msc), GFP_KERNEL);
 	if (msc == NULL) {
@@ -922,7 +974,8 @@ static int magicmouse_probe(struct hid_device *hdev,
 static void magicmouse_remove(struct hid_device *hdev)
 {
 	struct magicmouse_sc *msc = hid_get_drvdata(hdev);
-	cancel_delayed_work_sync(&msc->work);
+	if (msc)
+		cancel_delayed_work_sync(&msc->work);
 	hid_hw_stop(hdev);
 }