MdePkg, MdeModulePkg: ArmFfaLib: Expose FFA_ARGS and ArmCallFfa

FFA is a framework that supports various protocols built on top. i.e.
memory protocol, which is nothing that can be done through existing
interfaces.

Instead of requiring protocol authors to check conduit PCD in every
implementation, exposing the ArmCallFfa is a unified way to allow other
protocols to leverage FFA interfaces.

Continuous-integration-options: PatchCheck.ignore-multi-package
Signed-off-by: Kun Qin <kun.qin@microsoft.com>

MdePkg/Include/Library/ArmFfaLib.h

@@ -23,6 +23,30 @@
 
 #include <Library/ArmSmcLib.h>
 
+/**
+ * Arguments to call FF-A request via SMC/SVC.
+ */
+typedef struct ArmFfaArgs {
+  UINTN    Arg0;
+  UINTN    Arg1;
+  UINTN    Arg2;
+  UINTN    Arg3;
+  UINTN    Arg4;
+  UINTN    Arg5;
+  UINTN    Arg6;
+  UINTN    Arg7;
+  UINTN    Arg8;
+  UINTN    Arg9;
+  UINTN    Arg10;
+  UINTN    Arg11;
+  UINTN    Arg12;
+  UINTN    Arg13;
+  UINTN    Arg14;
+  UINTN    Arg15;
+  UINTN    Arg16;
+  UINTN    Arg17;
+} ARM_FFA_ARGS;
+
 #define FFA_RXTX_MAP_INPUT_PROPERTY_DEFAULT  0x00
 
 /** Implementation define arguments used in
@@ -73,6 +97,18 @@ typedef struct DirectMsgArgs {
   UINTN    Arg13;
 } DIRECT_MSG_ARGS;
 
+/**
+  Trigger FF-A ABI call according to PcdFfaLibConduitSmc.
+
+  @param [in, out]  FfaArgs        Ffa arguments
+
+**/
+VOID
+EFIAPI
+ArmCallFfa (
+  IN OUT ARM_FFA_ARGS  *FfaArgs
+  );
+
 /**
   Convert EFI_STATUS to FFA return code.