HID: magicmouse: Add MTP multi-touch device support

Apple M2 devices expose the multi-touch device over the HID over
DockChannel transport, which we represent as the HOST bus type. The
report format is the same, except the legacy mouse header is gone and
there is no enable request needed.

Signed-off-by: Hector Martin <marcan@marcan.st>

Author: marcan

drivers/hid/hid-magicmouse.c

@@ -61,6 +61,7 @@ MODULE_PARM_DESC(report_undeciphered, "Report undeciphered multi-touch state fie
 #define MOUSE2_REPORT_ID   0x12
 #define DOUBLE_REPORT_ID   0xf7
 #define SPI_REPORT_ID      0x02
+#define MTP_REPORT_ID      0x75
 #define USB_BATTERY_TIMEOUT_SEC 60
 
 #define MAX_CONTACTS 16
@@ -586,25 +587,32 @@ struct tp_finger {
 } __attribute__((packed, aligned(2)));
 
 /**
- * struct trackpad report
+ * vendor trackpad report
  *
- * @report_id:		reportid
- * @buttons:		HID Usage Buttons 3 1-bit reports
  * @num_fingers:	the number of fingers being reported in @fingers
- * @clicked:		same as @buttons
+ * @buttons:		same as HID buttons
  */
 struct tp_header {
+	// HID vendor part, up to 1751 bytes
+	u8 unknown[22];
+	u8 num_fingers;
+	u8 buttons;
+	u8 unknown3[14];
+};
+
+/**
+ * standard HID mouse report
+ *
+ * @report_id:		reportid
+ * @buttons:		HID Usage Buttons 3 1-bit reports
+ */
+struct tp_mouse_report {
 	// HID mouse report
 	u8 report_id;
 	u8 buttons;
 	u8 rel_x;
 	u8 rel_y;
 	u8 padding[4];
-	// HID vendor part, up to 1751 bytes
-	u8 unknown[22];
-	u8 num_fingers;
-	u8 clicked;
-	u8 unknown3[14];
 };
 
 static inline int le16_to_int(__le16 x)
@@ -634,7 +642,7 @@ static void report_finger_data(struct input_dev *input, int slot,
 	input_report_abs(input, ABS_MT_POSITION_Y, pos->y);
 }
 
-static int magicmouse_raw_event_spi(struct hid_device *hdev,
+static int magicmouse_raw_event_mtp(struct hid_device *hdev,
 		struct hid_report *report, u8 *data, int size)
 {
 	struct magicmouse_sc *msc = hid_get_drvdata(hdev);
@@ -651,9 +659,6 @@ static int magicmouse_raw_event_spi(struct hid_device *hdev,
 	// print_hex_dump_debug("appleft ev: ", DUMP_PREFIX_OFFSET, 16, 1, data,
 	// 		     size, false);
 
-	if (data[0] != SPI_REPORT_ID)
-		return 0;
-
 	/* Expect 46 bytes of prefix, and N * 30 bytes of touch data. */
 	if (size < hdr_sz || ((size - hdr_sz) % touch_sz) != 0)
 		return 0;
@@ -692,12 +697,26 @@ static int magicmouse_raw_event_spi(struct hid_device *hdev,
 	}
 
 	input_mt_sync_frame(input);
-	input_report_key(input, BTN_MOUSE, data[1] & 1);
+	input_report_key(input, BTN_MOUSE, tp_hdr->buttons & 1);
 
 	input_sync(input);
 	return 1;
 }
 
+static int magicmouse_raw_event_spi(struct hid_device *hdev,
+		struct hid_report *report, u8 *data, int size)
+{
+	const size_t hdr_sz = sizeof(struct tp_mouse_report);
+
+	if (size < hdr_sz)
+		return 0;
+
+	if (data[0] != SPI_REPORT_ID)
+		return 0;
+
+	return magicmouse_raw_event_mtp(hdev, report, data + hdr_sz, size - hdr_sz);
+}
+
 static int magicmouse_event(struct hid_device *hdev, struct hid_field *field,
 		struct hid_usage *usage, __s32 value)
 {
@@ -1119,7 +1138,7 @@ static int magicmouse_probe(struct hid_device *hdev,
 	struct hid_report *report;
 	int ret;
 
-	if (id->bus == BUS_SPI && id->vendor == SPI_VENDOR_ID_APPLE &&
+	if ((id->bus == BUS_SPI || id->bus == BUS_HOST) && id->vendor == SPI_VENDOR_ID_APPLE &&
 	    hdev->type != HID_TYPE_SPI_MOUSE)
 		return -ENODEV;
 
@@ -1131,7 +1150,10 @@ static int magicmouse_probe(struct hid_device *hdev,
 
 	// internal trackpad use a data format use input ops to avoid
 	// conflicts with the report ID.
-	if (id->vendor == SPI_VENDOR_ID_APPLE) {
+	if (id->bus == BUS_HOST) {
+		msc->input_ops.raw_event = magicmouse_raw_event_mtp;
+		msc->input_ops.setup_input = magicmouse_setup_input_spi;
+	} else if (id->bus == BUS_SPI) {
 		msc->input_ops.raw_event = magicmouse_raw_event_spi;
 		msc->input_ops.setup_input = magicmouse_setup_input_spi;
 	} else {
@@ -1199,6 +1221,9 @@ static int magicmouse_probe(struct hid_device *hdev,
 		break;
 	default:
 		switch (id->bus) {
+		case BUS_HOST:
+			report = hid_register_report(hdev, HID_INPUT_REPORT, MTP_REPORT_ID, 0);
+			break;
 		case BUS_SPI:
 			report = hid_register_report(hdev, HID_INPUT_REPORT, SPI_REPORT_ID, 0);
 			break;
@@ -1217,6 +1242,10 @@ static int magicmouse_probe(struct hid_device *hdev,
 	}
 	report->size = 6;
 
+	/* MTP devices do not need the MT enable, this is handled by the MTP driver */
+	if (id->bus == BUS_HOST)
+		return 0;
+
 	/*
 	 * Some devices repond with 'invalid report id' when feature
 	 * report switching it into multitouch mode is sent to it.
@@ -1312,6 +1341,8 @@ static const struct hid_device_id magic_mice[] = {
 		USB_DEVICE_ID_APPLE_MAGICTRACKPAD2_USBC), .driver_data = 0 },
 	{ HID_SPI_DEVICE(SPI_VENDOR_ID_APPLE, HID_ANY_ID),
 	  .driver_data = 0 },
+	{ HID_DEVICE(BUS_HOST, HID_GROUP_ANY, HOST_VENDOR_ID_APPLE,
+                     HID_ANY_ID), .driver_data = 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(hid, magic_mice);