ArmPkg: Add initial OpteeLib implementation

This is initial version of OP-TEE library that provides api's to
communicate with OP-TEE OS (Trusted OS based on ARM TrustZone) via
secure monitor calls. Currently it provides basic api to detect OP-TEE
presence via UID matching.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

ArmPkg/Library/OpteeLib/Optee.c

@@ -0,0 +1,46 @@
+/** @file
+  Api's to communicate with OP-TEE OS (Trusted OS based on ARM TrustZone) via
+  secure monitor calls.
+
+  Copyright (c) 2018, Linaro Ltd. All rights reserved.<BR>
+
+  This program and the accompanying materials
+  are licensed and made available under the terms and conditions of the BSD License
+  which accompanies this distribution.  The full text of the license may be found at
+  http://opensource.org/licenses/bsd-license.php
+
+  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+**/
+
+#include <Library/ArmSmcLib.h>
+#include <Library/BaseLib.h>
+#include <Library/OpteeLib.h>
+
+#include <IndustryStandard/ArmStdSmc.h>
+
+/**
+  Check for OP-TEE presence.
+**/
+BOOLEAN
+EFIAPI
+IsOpteePresent (
+  VOID
+  )
+{
+  ARM_SMC_ARGS ArmSmcArgs;
+
+  // Send a Trusted OS Calls UID command
+  ArmSmcArgs.Arg0 = ARM_SMC_ID_TOS_UID;
+  ArmCallSmc (&ArmSmcArgs);
+
+  if ((ArmSmcArgs.Arg0 == OPTEE_OS_UID0) &&
+      (ArmSmcArgs.Arg1 == OPTEE_OS_UID1) &&
+      (ArmSmcArgs.Arg2 == OPTEE_OS_UID2) &&
+      (ArmSmcArgs.Arg3 == OPTEE_OS_UID3)) {
+    return TRUE;
+  } else {
+    return FALSE;
+  }
+}