MdePkg/BaseRngLib: Add support for ARMv8.5 RNG instructions

Make BaseRngLib more generic by moving x86-specific functionality into
'Rand' and adding files under 'AArch64' to support the optional ARMv8.5
RNG instruction RNDR that is a part of FEAT_RNG.

Signed-off-by: Rebecca Cran <rebecca@nuviainc.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>
Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>

MdePkg/Library/BaseRngLib/BaseRngLibInternals.h

@@ -0,0 +1,78 @@
+/** @file
+
+  Architecture specific interface to RNG functionality.
+
+Copyright (c) 2021, NUVIA Inc. All rights reserved.<BR>
+
+SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#ifndef BASE_RNGLIB_INTERNALS_H_
+
+/**
+  Generates a 16-bit random number.
+
+  @param[out] Rand     Buffer pointer to store the 16-bit random value.
+
+  @retval TRUE         Random number generated successfully.
+  @retval FALSE        Failed to generate the random number.
+
+**/
+BOOLEAN
+EFIAPI
+ArchGetRandomNumber16 (
+  OUT UINT16 *Rand
+  );
+
+/**
+  Generates a 32-bit random number.
+
+  @param[out] Rand     Buffer pointer to store the 32-bit random value.
+
+  @retval TRUE         Random number generated successfully.
+  @retval FALSE        Failed to generate the random number.
+
+**/
+BOOLEAN
+EFIAPI
+ArchGetRandomNumber32 (
+  OUT UINT32 *Rand
+  );
+
+/**
+  Generates a 64-bit random number.
+
+  @param[out] Rand     Buffer pointer to store the 64-bit random value.
+
+  @retval TRUE         Random number generated successfully.
+  @retval FALSE        Failed to generate the random number.
+
+**/
+BOOLEAN
+EFIAPI
+ArchGetRandomNumber64 (
+  OUT UINT64 *Rand
+  );
+
+/**
+  Checks whether the RNG instruction is supported.
+
+  @retval TRUE         RNG instruction is supported.
+  @retval FALSE        RNG instruction is not supported.
+
+**/
+BOOLEAN
+EFIAPI
+ArchIsRngSupported (
+  VOID
+  );
+
+#if defined (MDE_CPU_AARCH64)
+
+// RNDR, Random Number
+#define RNDR      S3_3_C2_C4_0
+
+#endif
+
+#endif    // BASE_RNGLIB_INTERNALS_H_