HID: wiimote: add Nunchuk support

This moves the nunchuk parser over to an extension module. This allows to
make use of hotplugged Nunchuks instead of the old static parser.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-wiimote-core.c

@@ -444,6 +444,8 @@ static __u8 wiimote_cmd_read_ext(struct wiimote_data *wdata, __u8 *rmem)
 	    rmem[3] == 0xff && rmem[4] == 0xff && rmem[5] == 0xff)
 		return WIIMOTE_EXT_NONE;
 
+	if (rmem[4] == 0x00 && rmem[5] == 0x00)
+		return WIIMOTE_EXT_NUNCHUK;
 	if (rmem[4] == 0x04 && rmem[5] == 0x02)
 		return WIIMOTE_EXT_BALANCE_BOARD;
 
@@ -478,6 +480,9 @@ static bool wiimote_cmd_map_mp(struct wiimote_data *wdata, __u8 exttype)
 
 	/* map MP with correct pass-through mode */
 	switch (exttype) {
+	case WIIMOTE_EXT_NUNCHUK:
+		wmem = 0x05;
+		break;
 	default:
 		wmem = 0x04;
 		break;
@@ -1034,6 +1039,7 @@ out_release:
 static const char *wiimote_exttype_names[WIIMOTE_EXT_NUM] = {
 	[WIIMOTE_EXT_NONE] = "None",
 	[WIIMOTE_EXT_UNKNOWN] = "Unknown",
+	[WIIMOTE_EXT_NUNCHUK] = "Nintendo Wii Nunchuk",
 	[WIIMOTE_EXT_BALANCE_BOARD] = "Nintendo Wii Balance Board",
 };