Add support for 64-bit operation status values

For compatibility with 64-bit EFI status codes, opstatus values
are now treated as 64-bit rather than 32-bit. A new rpc_opstatus_t
type has been introduced in this change. Note that the FFARPC
still maps the opstatus value to a 32-bit regsiter value but
this is sign extended up to 64-bits in RPC callers.  The MM
Communicate RPC caller and endpoint handle 64-bit status values.

Signed-off-by: Julian Hall <julian.hall@arm.com>
Change-Id: I06a0883394f370ccb543ebab797973bb604ff489
diff --git a/components/rpc/common/interface/rpc_caller.h b/components/rpc/common/interface/rpc_caller.h
index 879d2cb..387489c 100644
--- a/components/rpc/common/interface/rpc_caller.h
+++ b/components/rpc/common/interface/rpc_caller.h
@@ -42,7 +42,7 @@
 	rpc_call_handle (*call_begin)(void *context, uint8_t **req_buf, size_t req_len);
 
 	rpc_status_t (*call_invoke)(void *context, rpc_call_handle handle, uint32_t opcode,
-		     	int *opstatus, uint8_t **resp_buf, size_t *resp_len);
+		     	rpc_opstatus_t *opstatus, uint8_t **resp_buf, size_t *resp_len);
 
 	void (*call_end)(void *context, rpc_call_handle handle);
 };
@@ -79,7 +79,7 @@
  * call_end() is called for the transaction.
  */
 RPC_CALLER_EXPORTED rpc_status_t rpc_caller_invoke(struct rpc_caller *s, rpc_call_handle handle,
-			uint32_t opcode, int *opstatus, uint8_t **resp_buf, size_t *resp_len);
+			uint32_t opcode, rpc_opstatus_t *opstatus, uint8_t **resp_buf, size_t *resp_len);
 
 /*
  * Ends the call transaction, allowing any resource associated with the
diff --git a/components/rpc/common/interface/rpc_status.h b/components/rpc/common/interface/rpc_status.h
index 0405a64..cba9dac 100644
--- a/components/rpc/common/interface/rpc_status.h
+++ b/components/rpc/common/interface/rpc_status.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2020-2021, Arm Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -21,6 +21,15 @@
  */
 typedef int32_t rpc_status_t;
 
+/** \brief RPC operation status code type
+ *
+ * Used for returning the endpoint specific operation status.
+ * Different service layer protocols will use different status
+ * value schemes. Status values returned by an operation are
+ * carried by the RPC layer using this type.
+ */
+typedef int64_t rpc_opstatus_t;
+
 #ifdef __cplusplus
 }
 #endif