diff --git a/plat/arm/css/sgi/aarch64/sgi_helper.S b/plat/arm/css/sgi/aarch64/sgi_helper.S
new file mode 100644
index 0000000..c435d8b
--- /dev/null
+++ b/plat/arm/css/sgi/aarch64/sgi_helper.S
@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch.h>
+#include <asm_macros.S>
+#include <platform_def.h>
+
+	.globl	plat_is_my_cpu_primary
+	.globl	plat_arm_calc_core_pos
+
+	/* -----------------------------------------------------
+	 * unsigned int plat_is_my_cpu_primary (void);
+	 *
+	 * Find out whether the current cpu is the primary
+	 * cpu (applicable only after a cold boot)
+	 * -----------------------------------------------------
+	 */
+func plat_is_my_cpu_primary
+	mov	x9, x30
+	bl	plat_my_core_pos
+	ldr	x1, =SGI_BOOT_CFG_ADDR
+	ldr	x1, [x1]
+	ubfx	x1, x1, #PLAT_CSS_PRIMARY_CPU_SHIFT, \
+			#PLAT_CSS_PRIMARY_CPU_BIT_WIDTH
+	cmp	x0, x1
+	cset	w0, eq
+	ret	x9
+endfunc plat_is_my_cpu_primary
+
+	/* -----------------------------------------------------
+	*  unsigned int plat_arm_calc_core_pos(uint64_t mpidr)
+	*  Helper function to calculate the core position.
+	* -----------------------------------------------------
+	*/
+func plat_arm_calc_core_pos
+	mrs     x2, mpidr_el1
+	ands    x2, x2, #MPIDR_MT_MASK
+	beq     1f
+	lsr     x0, x0, #MPIDR_AFF1_SHIFT
+1:
+	and	x1, x0, #MPIDR_CPU_MASK
+	and	x0, x0, #MPIDR_CLUSTER_MASK
+	add	x0, x1, x0, LSR #6
+	and     x0, x0, #MPIDR_AFFLVL_MASK
+	ret
+endfunc plat_arm_calc_core_pos