diff --git a/realm/include/platform.h b/realm/include/platform.h
new file mode 100644
index 0000000..de91c16
--- /dev/null
+++ b/realm/include/platform.h
@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2022-2023, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ */
+
+#ifndef PLATFORM_H
+#define PLATFORM_H
+
+/*
+ * Helper that returns a linear core ID from a MPID
+ * Need to provide a RSI_HOST_CALL to request this from Host platform.
+ */
+unsigned int platform_get_core_pos(u_register_t mpid)
+{
+	return 0U;
+}
+
+#endif /* PLATFORM_H */
diff --git a/realm/include/realm_rsi.h b/realm/include/realm_rsi.h
new file mode 100644
index 0000000..c7ea5a5
--- /dev/null
+++ b/realm/include/realm_rsi.h
@@ -0,0 +1,113 @@
+/*
+ * Copyright (c) 2022, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ */
+
+#ifndef REALM_RSI_H
+#define REALM_RSI_H
+
+#include <stdint.h>
+#include <host_shared_data.h>
+#include <tftf_lib.h>
+
+#define SMC_RSI_CALL_BASE	0xC4000190
+#define SMC_RSI_FID(_x)		(SMC_RSI_CALL_BASE + (_x))
+/*
+ * This file describes the Realm Services Interface (RSI) Application Binary
+ * Interface (ABI) for SMC calls made from within the Realm to the RMM and
+ * serviced by the RMM.
+ *
+ * See doc/rmm_interface.md for more details.
+ */
+
+/*
+ * The major version number of the RSI implementation.  Increase this whenever
+ * the binary format or semantics of the SMC calls change.
+ */
+#define RSI_ABI_VERSION_MAJOR		12U
+
+/*
+ * The minor version number of the RSI implementation.  Increase this when
+ * a bug is fixed, or a feature is added without breaking binary compatibility.
+ */
+#define RSI_ABI_VERSION_MINOR		0U
+
+#define RSI_ABI_VERSION_VAL		((RSI_ABI_VERSION_MAJOR << 16U) | \
+					 RSI_ABI_VERSION_MINOR)
+
+#define RSI_ABI_VERSION_GET_MAJOR(_version) ((_version) >> 16U)
+#define RSI_ABI_VERSION_GET_MINOR(_version) ((_version) & 0xFFFFU)
+
+
+/* RSI Status code enumeration as per Section D4.3.6 of the RMM Spec */
+typedef enum {
+	/* Command completed successfully */
+	RSI_SUCCESS = 0U,
+
+	/*
+	 * The value of a command input value
+	 * caused the command to fail
+	 */
+	RSI_ERROR_INPUT	= 1U,
+
+	/*
+	 * The state of the current Realm or current REC
+	 * does not match the state expected by the command
+	 */
+	RSI_ERROR_STATE	= 2U,
+
+	/* The operation requested by the command is not complete */
+	RSI_INCOMPLETE = 3U,
+
+	RSI_ERROR_COUNT
+} rsi_status_t;
+
+struct rsi_realm_config {
+	/* IPA width in bits */
+	SET_MEMBER(unsigned long ipa_width, 0, 0x1000);	/* Offset 0 */
+};
+
+/*
+ * arg0 == IPA address of target region
+ * arg1 == Size of target region in bytes
+ * arg2 == RIPAS value
+ * ret0 == Status / error
+ * ret1 == Top of modified IPA range
+ */
+
+#define RSI_HOST_CALL_NR_GPRS		7U
+
+struct rsi_host_call {
+	SET_MEMBER(struct {
+		/* Immediate value */
+		unsigned int imm;		/* Offset 0 */
+		/* Registers */
+		unsigned long gprs[RSI_HOST_CALL_NR_GPRS];
+		}, 0, 0x100);
+};
+
+/*
+ * arg0 == struct rsi_host_call addr
+ */
+#define RSI_HOST_CALL		SMC_RSI_FID(9U)
+
+
+#define RSI_ABI_VERSION		SMC_RSI_FID(0U)
+
+/*
+ * arg0 == struct rsi_realm_config address
+ */
+#define RSI_REALM_CONFIG	SMC_RSI_FID(6U)
+
+/* This function return RSI_ABI_VERSION */
+u_register_t rsi_get_version(void);
+
+/* This function will call the Host to request IPA of the NS shared buffer */
+u_register_t rsi_get_ns_buffer(void);
+
+/* This function call Host and request to exit Realm with proper exit code */
+void rsi_exit_to_host(enum host_call_cmd exit_code);
+
+#endif /* REALM_RSI_H */
diff --git a/realm/include/realm_tests.h b/realm/include/realm_tests.h
new file mode 100644
index 0000000..0e653ba
--- /dev/null
+++ b/realm/include/realm_tests.h
@@ -0,0 +1,17 @@
+/*
+ * Copyright (c) 2023, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ */
+
+#ifndef REALM_TESTS_H
+#define REALM_TESTS_H
+
+bool test_pmuv3_cycle_works_realm(void);
+bool test_pmuv3_event_works_realm(void);
+bool test_pmuv3_rmm_preserves(void);
+bool test_pmuv3_overflow_interrupt(void);
+
+#endif /* REALM_TESTS_H */
+