service/btm: Add basic implementation of GetCoreImpl()

Based off information on SwIPC and Switch Brew.

src/core/hle/service/btm/btm.cpp

@@ -4,6 +4,9 @@
 
 #include <memory>
 
+#include "common/logging/log.h"
+#include "core/hle/ipc_helpers.h"
+#include "core/hle/kernel/hle_ipc.h"
 #include "core/hle/service/btm/btm.h"
 #include "core/hle/service/service.h"
 #include "core/hle/service/sm/sm.h"
@@ -65,17 +68,48 @@ public:
     }
 };
 
+class IBtmSystemCore final : public ServiceFramework<IBtmSystemCore> {
+public:
+    explicit IBtmSystemCore() : ServiceFramework{"IBtmSystemCore"} {
+        // clang-format off
+        static const FunctionInfo functions[] = {
+            {0, nullptr, "StartGamepadPairingImpl"},
+            {1, nullptr, "CancelGamepadPairingImpl"},
+            {2, nullptr, "ClearGamepadPairingDatabaseImpl"},
+            {3, nullptr, "GetPairedGamepadCountImpl"},
+            {4, nullptr, "EnableRadioImpl"},
+            {5, nullptr, "DisableRadioImpl"},
+            {6, nullptr, "GetRadioOnOffImpl"},
+            {7, nullptr, "AcquireRadioEventImpl"},
+            {8, nullptr, "AcquireGamepadPairingEventImpl"},
+            {9, nullptr, "IsGamepadPairingStartedImpl"},
+        };
+        // clang-format on
+
+        RegisterHandlers(functions);
+    }
+};
+
 class BTM_SYS final : public ServiceFramework<BTM_SYS> {
 public:
     explicit BTM_SYS() : ServiceFramework{"btm:sys"} {
         // clang-format off
         static const FunctionInfo functions[] = {
-            {0, nullptr, "GetCoreImpl"},
+            {0, &BTM_SYS::GetCoreImpl, "GetCoreImpl"},
         };
         // clang-format on
 
         RegisterHandlers(functions);
     }
+
+private:
+    void GetCoreImpl(Kernel::HLERequestContext& ctx) {
+        IPC::ResponseBuilder rb{ctx, 2, 0, 1};
+        rb.Push(RESULT_SUCCESS);
+        rb.PushIpcInterface<IBtmSystemCore>();
+
+        LOG_DEBUG(Service_BTM, "called");
+    }
 };
 
 void InstallInterfaces(SM::ServiceManager& sm) {