service/lbl: Implement EnableVrMode, DisableVrMode and GetVrMode

Implements these functions according to the information available on
Switch Brew.

src/common/logging/backend.cpp

@@ -173,6 +173,7 @@ void FileBackend::Write(const Entry& entry) {
     SUB(Service, Friend)                                                                           \
     SUB(Service, FS)                                                                               \
     SUB(Service, HID)                                                                              \
+    SUB(Service, LBL)                                                                              \
     SUB(Service, LDN)                                                                              \
     SUB(Service, LM)                                                                               \
     SUB(Service, MM)                                                                               \

src/common/logging/log.h

@@ -60,6 +60,7 @@ enum class Class : ClassType {
     Service_Friend,    ///< The friend service
     Service_FS,        ///< The FS (Filesystem) service
     Service_HID,       ///< The HID (Human interface device) service
+    Service_LBL,       ///< The LBL (LCD backlight) service
     Service_LDN,       ///< The LDN (Local domain network) service
     Service_LM,        ///< The LM (Logger) service
     Service_MM,        ///< The MM (Multimedia) service

src/core/hle/service/lbl/lbl.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/lbl/lbl.h"
 #include "core/hle/service/service.h"
 #include "core/hle/service/sm/sm.h"
@@ -41,14 +44,43 @@ public:
             {23, nullptr, "Unknown20"},
             {24, nullptr, "Unknown21"},
             {25, nullptr, "Unknown22"},
-            {26, nullptr, "EnableVrMode"},
-            {27, nullptr, "DisableVrMode"},
-            {28, nullptr, "GetVrMode"},
+            {26, &LBL::EnableVrMode, "EnableVrMode"},
+            {27, &LBL::DisableVrMode, "DisableVrMode"},
+            {28, &LBL::GetVrMode, "GetVrMode"},
         };
         // clang-format on
 
         RegisterHandlers(functions);
     }
+
+private:
+    void EnableVrMode(Kernel::HLERequestContext& ctx) {
+        IPC::ResponseBuilder rb{ctx, 2};
+        rb.Push(RESULT_SUCCESS);
+
+        vr_mode_enabled = true;
+
+        LOG_DEBUG(Service_LBL, "called");
+    }
+
+    void DisableVrMode(Kernel::HLERequestContext& ctx) {
+        IPC::ResponseBuilder rb{ctx, 2};
+        rb.Push(RESULT_SUCCESS);
+
+        vr_mode_enabled = false;
+
+        LOG_DEBUG(Service_LBL, "called");
+    }
+
+    void GetVrMode(Kernel::HLERequestContext& ctx) {
+        IPC::ResponseBuilder rb{ctx, 3};
+        rb.Push(RESULT_SUCCESS);
+        rb.Push(vr_mode_enabled);
+
+        LOG_DEBUG(Service_LBL, "called");
+    }
+
+    bool vr_mode_enabled = false;
 };
 
 void InstallInterfaces(SM::ServiceManager& sm) {