Enable IBM PLDM OEM commands support

Create folder structure (oem/ibm) for ibm pldm oem commands. Move the
files from the ibm-pldm-oem repo [https://github.com/openbmc/ibm-pldm-oem]
to the folder oem/ibm/ under the pldm repo and enable conditional
compilation for it. The test files are also conditionally compiled.

You would need to provide --enable-oem-ibm to configure.

This is done to simplify the build time and runtime dependencies between the
standard and oem implementations.

Signed-off-by: Jinu Joy Thomas <jinu.joy.thomas@in.ibm.com>
Change-Id: Iaa93c73faff87290e3d3d5d155d9ecae6e7ee6f9
diff --git a/oem/ibm/libpldm/file_io.c b/oem/ibm/libpldm/file_io.c
new file mode 100644
index 0000000..ca33cef
--- /dev/null
+++ b/oem/ibm/libpldm/file_io.c
@@ -0,0 +1,54 @@
+#include "file_io.h"
+#include <endian.h>
+#include <string.h>
+
+int decode_rw_file_memory_req(const uint8_t *msg, size_t payload_length,
+			      uint32_t *file_handle, uint32_t *offset,
+			      uint32_t *length, uint64_t *address)
+{
+	if (msg == NULL || file_handle == NULL || offset == NULL ||
+	    length == NULL || address == NULL) {
+		return PLDM_ERROR_INVALID_DATA;
+	}
+
+	if (payload_length != PLDM_RW_FILE_MEM_REQ_BYTES) {
+		return PLDM_ERROR_INVALID_LENGTH;
+	}
+
+	*file_handle = le32toh(*((uint32_t *)msg));
+	*offset = le32toh(*((uint32_t *)(msg + sizeof(*file_handle))));
+	*length = le32toh(
+	    *((uint32_t *)(msg + sizeof(*file_handle) + sizeof(*offset))));
+	*address = le64toh(*((uint64_t *)(msg + sizeof(*file_handle) +
+					  sizeof(*offset) + sizeof(*length))));
+
+	return PLDM_SUCCESS;
+}
+
+int encode_rw_file_memory_resp(uint8_t instance_id, uint8_t command,
+			       uint8_t completion_code, uint32_t length,
+			       struct pldm_msg *msg)
+{
+	struct pldm_header_info header = {0};
+	int rc = PLDM_SUCCESS;
+
+	uint8_t *payload = msg->payload;
+	*payload = completion_code;
+
+	header.msg_type = PLDM_RESPONSE;
+	header.instance = instance_id;
+	header.pldm_type = PLDM_IBM_OEM_TYPE;
+	header.command = command;
+
+	if ((rc = pack_pldm_header(&header, &(msg->hdr))) > PLDM_SUCCESS) {
+		return rc;
+	}
+
+	if (msg->payload[0] == PLDM_SUCCESS) {
+		uint8_t *dst = msg->payload + sizeof(completion_code);
+		length = htole32(length);
+		memcpy(dst, &length, sizeof(length));
+	}
+
+	return PLDM_SUCCESS;
+}