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/Include/Library/OpteeLib.h

@@ -0,0 +1,34 @@
+/** @file
+  OP-TEE specific header file.
+
+  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.
+
+**/
+
+#ifndef _OPTEE_H_
+#define _OPTEE_H_
+
+/*
+ * The 'Trusted OS Call UID' is supposed to return the following UUID for
+ * OP-TEE OS. This is a 128-bit value.
+ */
+#define OPTEE_OS_UID0          0x384fb3e0
+#define OPTEE_OS_UID1          0xe7f811e3
+#define OPTEE_OS_UID2          0xaf630002
+#define OPTEE_OS_UID3          0xa5d5c51b
+
+BOOLEAN
+EFIAPI
+IsOpteePresent (
+  VOID
+  );
+
+#endif