diff --git a/Source/Core/Core/HW/SI/SI_Device.cpp b/Source/Core/Core/HW/SI/SI_Device.cpp
index 5717fe10a9..401b1178a7 100644
--- a/Source/Core/Core/HW/SI/SI_Device.cpp
+++ b/Source/Core/Core/HW/SI/SI_Device.cpp
@@ -20,9 +20,15 @@
 #include "Core/HW/SI/SI_DeviceGCSteeringWheel.h"
 #include "Core/HW/SI/SI_DeviceKeyboard.h"
 #include "Core/HW/SI/SI_DeviceNull.h"
+#include "Core/HW/SystemTimers.h"
 
 namespace SerialInterface
 {
+constexpr u64 GC_BITS_PER_SECOND = 200000;
+constexpr u64 GBA_BITS_PER_SECOND = 250000;
+constexpr u64 GC_STOP_BIT_NS = 6500;
+constexpr u64 GBA_STOP_BIT_NS = 14000;
+
 std::ostream& operator<<(std::ostream& stream, SIDevices device)
 {
   stream << static_cast<std::underlying_type_t<SIDevices>>(device);
@@ -101,6 +107,44 @@ void ISIDevice::OnEvent(u64 userdata, s64 cycles_late)
 {
 }
 
+int SIDevice_GetGBATransferTime(EBufferCommands cmd)
+{
+  u64 gc_bytes_transferred = 1;
+  u64 gba_bytes_transferred = 1;
+  u64 stop_bits_ns = GC_STOP_BIT_NS + GBA_STOP_BIT_NS;
+
+  switch (cmd)
+  {
+  case EBufferCommands::CMD_RESET:
+  case EBufferCommands::CMD_STATUS:
+  {
+    gba_bytes_transferred = 3;
+    break;
+  }
+  case EBufferCommands::CMD_READ_GBA:
+  {
+    gba_bytes_transferred = 5;
+    break;
+  }
+  case EBufferCommands::CMD_WRITE_GBA:
+  {
+    gc_bytes_transferred = 5;
+    break;
+  }
+  default:
+  {
+    gba_bytes_transferred = 0;
+    break;
+  }
+  }
+
+  u64 cycles =
+      (gba_bytes_transferred * 8 * SystemTimers::GetTicksPerSecond() / GBA_BITS_PER_SECOND) +
+      (gc_bytes_transferred * 8 * SystemTimers::GetTicksPerSecond() / GC_BITS_PER_SECOND) +
+      (stop_bits_ns * SystemTimers::GetTicksPerSecond() / 1000000000LL);
+  return static_cast<int>(cycles);
+}
+
 // Check if a device class is inheriting from CSIDevice_GCController
 // The goal of this function is to avoid special casing a long list of
 // device types when there is no "real" input device, e.g. when playing
diff --git a/Source/Core/Core/HW/SI/SI_Device.h b/Source/Core/Core/HW/SI/SI_Device.h
index 14bd83201c..c2ae9bef87 100644
--- a/Source/Core/Core/HW/SI/SI_Device.h
+++ b/Source/Core/Core/HW/SI/SI_Device.h
@@ -130,6 +130,7 @@ protected:
   SIDevices m_device_type;
 };
 
+int SIDevice_GetGBATransferTime(EBufferCommands cmd);
 bool SIDevice_IsGCController(SIDevices type);
 
 std::unique_ptr<ISIDevice> SIDevice_Create(SIDevices device, int port_number);
diff --git a/Source/Core/Core/HW/SI/SI_DeviceGBA.cpp b/Source/Core/Core/HW/SI/SI_DeviceGBA.cpp
index 57679bbe50..95ab599a8f 100644
--- a/Source/Core/Core/HW/SI/SI_DeviceGBA.cpp
+++ b/Source/Core/Core/HW/SI/SI_DeviceGBA.cpp
@@ -34,52 +34,10 @@ int s_num_connected;
 Common::Flag s_server_running;
 }  // namespace
 
-constexpr auto GC_BITS_PER_SECOND = 200000;
-constexpr auto GBA_BITS_PER_SECOND = 250000;
-constexpr auto GC_STOP_BIT_NS = 6500;
-constexpr auto GBA_STOP_BIT_NS = 14000;
 constexpr auto SEND_MAX_SIZE = 5, RECV_MAX_SIZE = 5;
 
 // --- GameBoy Advance "Link Cable" ---
 
-static int GetTransferTime(EBufferCommands cmd)
-{
-  u64 gc_bytes_transferred = 1;
-  u64 gba_bytes_transferred = 1;
-  u64 stop_bits_ns = GC_STOP_BIT_NS + GBA_STOP_BIT_NS;
-
-  switch (cmd)
-  {
-  case EBufferCommands::CMD_RESET:
-  case EBufferCommands::CMD_STATUS:
-  {
-    gba_bytes_transferred = 3;
-    break;
-  }
-  case EBufferCommands::CMD_READ_GBA:
-  {
-    gba_bytes_transferred = 5;
-    break;
-  }
-  case EBufferCommands::CMD_WRITE_GBA:
-  {
-    gc_bytes_transferred = 5;
-    break;
-  }
-  default:
-  {
-    gba_bytes_transferred = 0;
-    break;
-  }
-  }
-
-  u64 cycles =
-      (gba_bytes_transferred * 8 * SystemTimers::GetTicksPerSecond() / GBA_BITS_PER_SECOND) +
-      (gc_bytes_transferred * 8 * SystemTimers::GetTicksPerSecond() / GC_BITS_PER_SECOND) +
-      (stop_bits_ns * SystemTimers::GetTicksPerSecond() / 1000000000LL);
-  return static_cast<int>(cycles);
-}
-
 static void GBAConnectionWaiter()
 {
   s_server_running.Set();
@@ -336,7 +294,7 @@ int CSIDevice_GBA::RunBuffer(u8* buffer, int request_length)
   {
     int elapsed_time = static_cast<int>(CoreTiming::GetTicks() - m_timestamp_sent);
     // Tell SI to ask again after TransferInterval() cycles
-    if (GetTransferTime(m_last_cmd) > elapsed_time)
+    if (SIDevice_GetGBATransferTime(m_last_cmd) > elapsed_time)
       return 0;
     m_next_action = NextAction::ReceiveResponse;
     [[fallthrough]];
@@ -383,7 +341,7 @@ int CSIDevice_GBA::RunBuffer(u8* buffer, int request_length)
 
 int CSIDevice_GBA::TransferInterval()
 {
-  return GetTransferTime(m_last_cmd);
+  return SIDevice_GetGBATransferTime(m_last_cmd);
 }
 
 bool CSIDevice_GBA::GetData(u32& hi, u32& low)