feat(rmm): add psci api to realms

add wrappers for PSCI APIs
CPU_ON
CPU_OFF
PSCI_AFFINITY_INFO
PSCI_FEATURES

Signed-off-by: Shruti Gupta <shruti.gupta@arm.com>
Change-Id: Ice7bc03d052a0726163c7a31a32f59688e7f516b
diff --git a/realm/realm_psci.c b/realm/realm_psci.c
new file mode 100644
index 0000000..2a5b951
--- /dev/null
+++ b/realm/realm_psci.c
@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2023, Arm Limited. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ *
+ */
+
+#include <debug.h>
+#include <psci.h>
+#include <realm_def.h>
+#include <tftf_lib.h>
+
+typedef void (*secondary_ep_t)(u_register_t);
+static secondary_ep_t entrypoint[MAX_REC_COUNT];
+static u_register_t context_id[MAX_REC_COUNT];
+void realm_entrypoint(void);
+void realm_payload_main(void);
+
+void realm_cpu_off(void)
+{
+	smc_args args = { SMC_PSCI_CPU_OFF };
+
+	tftf_smc(&args);
+}
+
+u_register_t realm_cpu_on(u_register_t mpidr, uintptr_t ep, u_register_t cxt_id)
+{
+	smc_args args;
+	smc_ret_values ret_vals;
+
+
+	if (mpidr > MAX_REC_COUNT) {
+		return PSCI_E_INVALID_PARAMS;
+	}
+
+	if (entrypoint[mpidr] != NULL) {
+		return PSCI_E_ALREADY_ON;
+	}
+
+	args.fid = SMC_PSCI_CPU_ON;
+	args.arg1 = mpidr;
+	args.arg2 = (u_register_t)realm_entrypoint;
+	args.arg3 = cxt_id;
+	entrypoint[mpidr] = (secondary_ep_t)ep;
+	context_id[mpidr] = cxt_id;
+	ret_vals = tftf_smc(&args);
+	return ret_vals.ret0;
+}
+
+u_register_t realm_psci_affinity_info(u_register_t target_affinity,
+		uint32_t lowest_affinity_level)
+{
+	smc_args args;
+	smc_ret_values ret_vals;
+
+	args.fid = SMC_PSCI_AFFINITY_INFO;
+	args.arg1 = target_affinity;
+	args.arg2 = lowest_affinity_level;
+	ret_vals = tftf_smc(&args);
+	return ret_vals.ret0;
+}
+
+u_register_t realm_psci_features(uint32_t psci_func_id)
+{
+
+	smc_args args;
+	smc_ret_values ret_vals;
+
+	args.fid = SMC_PSCI_FEATURES;
+	args.arg1 = psci_func_id;
+	ret_vals = tftf_smc(&args);
+	return ret_vals.ret0;
+}
+
+void realm_secondary_entrypoint(u_register_t cxt_id)
+{
+	u_register_t my_mpidr;
+	secondary_ep_t ep;
+
+	my_mpidr = read_mpidr_el1() & MPID_MASK;
+	ep = entrypoint[my_mpidr];
+	if (ep != NULL) {
+		entrypoint[my_mpidr] = NULL;
+		context_id[my_mpidr] = 0;
+		(ep)(context_id[my_mpidr]);
+	} else {
+		/*
+		 * Host can execute Rec directly without CPU_ON
+		 * from Realm, if Rec is created RUNNABLE
+		 * Jump to main in this case.
+		 */
+		while (true) {
+			realm_payload_main();
+		}
+	}
+	realm_cpu_off();
+}