Add protocol definitions for smm_variable

Adds protocol definition for the SMM Variable service. Protocol
files are based on EDK2 originals from:
https://github.com/tianocore/edk2/commits/master
b4da6c29f1d36031e04212f53277ce0dcba309f1
Structures and defines are required to be align for compatibility
between EDK2 and TS components.

Signed-off-by: Julian Hall <julian.hall@arm.com>
Change-Id: I3a478cdc5d3a849810abf6c699027f65594b4a83
diff --git a/protocols/common/efi/efi_status.h b/protocols/common/efi/efi_status.h
new file mode 100644
index 0000000..40c44a1
--- /dev/null
+++ b/protocols/common/efi/efi_status.h
@@ -0,0 +1,59 @@
+/*
+ * Copyright (c) 2021, Arm Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef COMMON_EFI_STATUS_H
+#define COMMON_EFI_STATUS_H
+
+#include <limits.h>
+#include <stdint.h>
+
+/**
+ * Common EFI status type
+ */
+typedef uint32_t efi_status_t;
+
+/* For error class status codes */
+#define EFI_ERROR(s)				((1U << ((CHAR_BIT * sizeof(efi_status_t)) - 1)) | s)
+
+/**
+ * Common EFI status codes
+ */
+#define EFI_SUCCESS					0x0
+#define EFI_LOAD_ERROR				EFI_ERROR(0x01)
+#define EFI_INVALID_PARAMETER		EFI_ERROR(0x02)
+#define EFI_UNSUPPORTED				EFI_ERROR(0x03)
+#define EFI_BAD_BUFFER_SIZE			EFI_ERROR(0x04)
+#define EFI_BUFFER_TOO_SMALL		EFI_ERROR(0x05)
+#define EFI_NOT_READY				EFI_ERROR(0x06)
+#define EFI_DEVICE_ERROR			EFI_ERROR(0x07)
+#define EFI_WRITE_PROTECTED			EFI_ERROR(0x08)
+#define EFI_OUT_OF_RESOURCES		EFI_ERROR(0x09)
+#define EFI_VOLUME_CORRUPTED		EFI_ERROR(0x0a)
+#define EFI_VOLUME_FULL				EFI_ERROR(0x0b)
+#define EFI_NO_MEDIA				EFI_ERROR(0x0c)
+#define EFI_MEDIA_CHANGED			EFI_ERROR(0x0d)
+#define EFI_NOT_FOUND				EFI_ERROR(0x0e)
+#define EFI_ACCESS_DENIED			EFI_ERROR(0x0f)
+#define EFI_NO_RESPONSE				EFI_ERROR(0x10)
+#define EFI_NO_MAPPING				EFI_ERROR(0x11)
+#define EFI_TIMEOUT					EFI_ERROR(0x12)
+#define EFI_NOT_STARTED				EFI_ERROR(0x13)
+#define EFI_ALREADY_STARTED			EFI_ERROR(0x14)
+#define EFI_ABORTED					EFI_ERROR(0x15)
+#define EFI_ICMP_ERROR				EFI_ERROR(0x16)
+#define EFI_TFTP_ERROR				EFI_ERROR(0x17)
+#define EFI_PROTOCOL_ERROR			EFI_ERROR(0x18)
+#define EFI_INCOMPATIBLE_VERSION	EFI_ERROR(0x19)
+#define EFI_SECURITY_VIOLATION		EFI_ERROR(0x1a)
+#define EFI_CRC_ERROR				EFI_ERROR(0x1b)
+#define EFI_END_OF_MEDIA			EFI_ERROR(0x1c)
+#define EFI_END_OF_FILE				EFI_ERROR(0x1f)
+#define EFI_INVALID_LANGUAGE		EFI_ERROR(0x20)
+#define EFI_COMPROMISED_DATA		EFI_ERROR(0x21)
+#define EFI_HTTP_ERROR				EFI_ERROR(0x23)
+
+
+#endif /* COMMON_EFI_STATUS_H */