diff --git a/services/spd/trusty/generic-arm64-smcall.c b/services/spd/trusty/generic-arm64-smcall.c
index 3ffc13d..5c3a628 100644
--- a/services/spd/trusty/generic-arm64-smcall.c
+++ b/services/spd/trusty/generic-arm64-smcall.c
@@ -16,9 +16,16 @@
 #ifdef GICD_BASE
 #define PLAT_ARM_GICD_BASE GICD_BASE
 #define PLAT_ARM_GICC_BASE GICC_BASE
+#ifdef GICR_BASE
+#define PLAT_ARM_GICR_BASE GICR_BASE
+#endif
 #else
 #error PLAT_ARM_GICD_BASE or GICD_BASE must be defined
 #endif
+#endif
+
+#ifndef PLAT_ARM_GICR_BASE
+#define PLAT_ARM_GICR_BASE SMC_UNK
 #endif
 
 int trusty_disable_serial_debug;
@@ -57,12 +64,15 @@
 static uint64_t trusty_get_reg_base(uint32_t reg)
 {
 	switch (reg) {
-	case 0:
+	case SMC_GET_GIC_BASE_GICD:
 		return PLAT_ARM_GICD_BASE;
 
-	case 1:
+	case SMC_GET_GIC_BASE_GICC:
 		return PLAT_ARM_GICC_BASE;
 
+	case SMC_GET_GIC_BASE_GICR:
+		return PLAT_ARM_GICR_BASE;
+
 	default:
 		NOTICE("%s(0x%x) unknown reg\n", __func__, reg);
 		return SMC_UNK;