diff --git a/ArmPlatformPkg/Include/Library/ArmPlatformLib.h b/ArmPlatformPkg/Include/Library/ArmPlatformLib.h
index 94ad5c176f..ed631f3c42 100644
--- a/ArmPlatformPkg/Include/Library/ArmPlatformLib.h
+++ b/ArmPlatformPkg/Include/Library/ArmPlatformLib.h
@@ -96,6 +96,22 @@ ArmPlatformGetBootMode (
   VOID
   );
 
+/**
+  First platform specific function to be called in the PEI phase
+
+  This function is actually the first function called by the PrePi
+  or PrePeiCore modules. It allows to retrieve arguments passed to
+  the UEFI firmware through the CPU registers.
+
+  This function might be written into assembler as no stack are set
+  when the function is invoked.
+
+**/
+VOID
+ArmPlatformPeiBootAction (
+  VOID
+  );
+
 /**
   Initialize controllers that must setup in the normal world