WiimoteReal: hidapi: Add support for the Balance Board

A name change isn't enough for the DolphinBar; we have to actually
query the Wiimote to know if the Wiimote is a Balance Board.

Source/Core/Core/HW/WiimoteReal/IOhidapi.cpp

@@ -70,17 +70,17 @@ void WiimoteScannerHidapi::FindWiimotes(std::vector<Wiimote*>& wiimotes, Wiimote
     if (!is_wiimote || s_known_paths.count(device->path) != 0 || !IsDeviceUsable(device->path))
       continue;
 
-    const bool is_balance_board = IsBalanceBoardName(name);
-    NOTICE_LOG(WIIMOTE, "Found %s at %s: %ls %ls (%04hx:%04hx)",
-               is_balance_board ? "balance board" : "Wiimote", device->path,
-               device->manufacturer_string, device->product_string, device->vendor_id,
-               device->product_id);
-
-    Wiimote* wiimote = new WiimoteHidapi(device->path);
+    auto* wiimote = new WiimoteHidapi(device->path);
+    const bool is_balance_board = IsBalanceBoardName(name) || wiimote->IsBalanceBoard();
     if (is_balance_board)
       board = wiimote;
     else
       wiimotes.push_back(wiimote);
+
+    NOTICE_LOG(WIIMOTE, "Found %s at %s: %ls %ls (%04hx:%04hx)",
+               is_balance_board ? "balance board" : "Wiimote", device->path,
+               device->manufacturer_string, device->product_string, device->vendor_id,
+               device->product_id);
   }
   hid_free_enumeration(list);
 }
@@ -98,6 +98,9 @@ WiimoteHidapi::~WiimoteHidapi()
 
 bool WiimoteHidapi::ConnectInternal()
 {
+  if (m_handle != nullptr)
+    return true;
+
   m_handle = hid_open_path(m_device_path.c_str());
   if (m_handle == nullptr)
   {

Source/Core/Core/HW/WiimoteReal/WiimoteReal.cpp

@@ -242,6 +242,71 @@ bool Wiimote::Write()
   return ret != 0;
 }
 
+bool Wiimote::IsBalanceBoard()
+{
+  if (!ConnectInternal())
+    return false;
+  // Initialise the extension by writing 0x55 to 0xa400f0, then writing 0x00 to 0xa400fb.
+  static const u8 init_extension_rpt1[MAX_PAYLOAD] = {
+      WM_SET_REPORT | WM_BT_OUTPUT, WM_WRITE_DATA, 0x04, 0xa4, 0x00, 0xf0, 0x01, 0x55};
+  static const u8 init_extension_rpt2[MAX_PAYLOAD] = {
+      WM_SET_REPORT | WM_BT_OUTPUT, WM_WRITE_DATA, 0x04, 0xa4, 0x00, 0xfb, 0x01, 0x00};
+  static const u8 status_report[] = {WM_SET_REPORT | WM_BT_OUTPUT, WM_REQUEST_STATUS, 0};
+  if (!IOWrite(init_extension_rpt1, sizeof(init_extension_rpt1)) ||
+      !IOWrite(init_extension_rpt2, sizeof(init_extension_rpt2)))
+  {
+    ERROR_LOG(WIIMOTE, "IsBalanceBoard(): Failed to initialise extension.");
+    return false;
+  }
+
+  int ret = IOWrite(status_report, sizeof(status_report));
+  u8 buf[MAX_PAYLOAD];
+  while (ret != 0)
+  {
+    ret = IORead(buf);
+    if (ret == -1)
+      continue;
+
+    switch (buf[1])
+    {
+    case WM_STATUS_REPORT:
+    {
+      const auto* status = reinterpret_cast<wm_status_report*>(&buf[2]);
+      // A Balance Board has a Balance Board extension.
+      if (!status->extension)
+        return false;
+      // Read two bytes from 0xa400fe to identify the extension.
+      static const u8 identify_ext_rpt[] = {
+          WM_SET_REPORT | WM_BT_OUTPUT, WM_READ_DATA, 0x04, 0xa4, 0x00, 0xfe, 0x02, 0x00};
+      ret = IOWrite(identify_ext_rpt, sizeof(identify_ext_rpt));
+      break;
+    }
+    case WM_READ_DATA_REPLY:
+    {
+      const auto* reply = reinterpret_cast<wm_read_data_reply*>(&buf[2]);
+      if (Common::swap16(reply->address) != 0x00fe)
+      {
+        ERROR_LOG(WIIMOTE, "IsBalanceBoard(): Received unexpected data reply for address %X",
+                  Common::swap16(reply->address));
+        return false;
+      }
+      // A Balance Board ext can be identified by checking for 0x0402.
+      return reply->data[0] == 0x04 && reply->data[1] == 0x02;
+    }
+    case WM_ACK_DATA:
+    {
+      const auto* ack = reinterpret_cast<wm_acknowledge*>(&buf[2]);
+      if (ack->reportID == WM_READ_DATA && ack->errorID != 0x00)
+      {
+        WARN_LOG(WIIMOTE, "Failed to read from 0xa400fe, assuming Wiimote is not a Balance Board.");
+        return false;
+      }
+    }
+    }
+  }
+  return false;
+}
+
 static bool IsDataReport(const Report& rpt)
 {
   return rpt.size() >= 2 && rpt[1] >= WM_REPORT_CORE;

Source/Core/Core/HW/WiimoteReal/WiimoteReal.h

@@ -41,6 +41,8 @@ public:
   void Read();
   bool Write();
 
+  bool IsBalanceBoard();
+
   void StartThread();
   void StopThread();