diff --git a/arch/arm64/include/asm/acpi.h b/arch/arm64/include/asm/acpi.h
index e877967..022f4ad 100644
--- a/arch/arm64/include/asm/acpi.h
+++ b/arch/arm64/include/asm/acpi.h
@@ -14,6 +14,27 @@
 
 /* Basic configuration for ACPI */
 #ifdef	CONFIG_ACPI
+/*
+ * ACPI 5.1 only has two explicit methods to
+ * boot up SMP, PSCI and Parking protocol,
+ * but the Parking protocol is only defined
+ * for ARMv7 now, so make PSCI as the only
+ * way for the SMP boot protocol before some
+ * updates for the ACPI spec or the Parking
+ * protocol spec.
+ *
+ * This enum is intend to make the boot method
+ * scalable when above updates are happended,
+ * which NOT means to support all of them.
+ */
+enum acpi_smp_boot_protocol {
+	ACPI_SMP_BOOT_PSCI,
+	ACPI_SMP_BOOT_PARKING_PROTOCOL,
+	ACPI_SMP_BOOT_PROTOCOL_MAX
+};
+
+enum acpi_smp_boot_protocol smp_boot_protocol(void);
+
 #define acpi_strict 1	/* No out-of-spec workarounds on ARM64 */
 extern int acpi_disabled;
 extern int acpi_noirq;
diff --git a/arch/arm64/include/asm/smp.h b/arch/arm64/include/asm/smp.h
index a498f2c..282932c2 100644
--- a/arch/arm64/include/asm/smp.h
+++ b/arch/arm64/include/asm/smp.h
@@ -39,7 +39,8 @@ extern void show_ipi_list(struct seq_file *p, int prec);
 extern void handle_IPI(int ipinr, struct pt_regs *regs);
 
 /*
- * Setup the set of possible CPUs (via set_cpu_possible)
+ * Discover the set of possible CPUs and determine their
+ * SMP operations.
  */
 extern void smp_init_cpus(void);
 
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index 9e07d99..8a54b4e 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -170,6 +170,15 @@ static int __init acpi_parse_madt_gic_cpu_interface_entries(void)
 	return 0;
 }
 
+/* Protocol to bring up secondary CPUs */
+enum acpi_smp_boot_protocol smp_boot_protocol(void)
+{
+	if (acpi_psci_present())
+		return ACPI_SMP_BOOT_PSCI;
+	else
+		return ACPI_SMP_BOOT_PARKING_PROTOCOL;
+}
+
 static int __init acpi_parse_fadt(struct acpi_table_header *table)
 {
 	struct acpi_table_fadt *fadt = (struct acpi_table_fadt *)table;
diff --git a/arch/arm64/kernel/cpu_ops.c b/arch/arm64/kernel/cpu_ops.c
index d62d12f..05bc314 100644
--- a/arch/arm64/kernel/cpu_ops.c
+++ b/arch/arm64/kernel/cpu_ops.c
@@ -16,11 +16,13 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <asm/cpu_ops.h>
-#include <asm/smp_plat.h>
 #include <linux/errno.h>
 #include <linux/of.h>
 #include <linux/string.h>
+#include <linux/acpi.h>
+
+#include <asm/cpu_ops.h>
+#include <asm/smp_plat.h>
 
 extern const struct cpu_operations smp_spin_table_ops;
 extern const struct cpu_operations cpu_psci_ops;
@@ -49,12 +51,44 @@ static const struct cpu_operations * __init cpu_get_ops(const char *name)
 	return NULL;
 }
 
+#ifdef CONFIG_ACPI
+/*
+ * Get a cpu's boot method in the ACPI way.
+ */
+static char * __init acpi_get_cpu_boot_method(void)
+{
+	/*
+	 * For ACPI 5.1, only two kind of methods are provided,
+	 * Parking protocol and PSCI, but Parking protocol is
+	 * specified for ARMv7 only, so make PSCI as the only method
+	 * for SMP initialization before the ACPI spec or Parking
+	 * protocol spec is updated.
+	 */
+	switch (smp_boot_protocol()) {
+	case ACPI_SMP_BOOT_PSCI:
+		return "psci";
+	case ACPI_SMP_BOOT_PARKING_PROTOCOL:
+	default:
+		return NULL;
+	}
+}
+#else
+static inline char * __init acpi_get_cpu_boot_method(void) { return NULL; }
+#endif
+
 /*
- * Read a cpu's enable method from the device tree and record it in cpu_ops.
+ * Read a cpu's enable method and record it in cpu_ops.
  */
 int __init cpu_read_ops(struct device_node *dn, int cpu)
 {
-	const char *enable_method = of_get_property(dn, "enable-method", NULL);
+	const char *enable_method;
+
+	if (!acpi_disabled) {
+		enable_method = acpi_get_cpu_boot_method();
+		goto get_ops;
+	}
+
+	enable_method = of_get_property(dn, "enable-method", NULL);
 	if (!enable_method) {
 		/*
 		 * The boot CPU may not have an enable method (e.g. when
@@ -66,10 +100,17 @@ int __init cpu_read_ops(struct device_node *dn, int cpu)
 		return -ENOENT;
 	}
 
+get_ops:
 	cpu_ops[cpu] = cpu_get_ops(enable_method);
 	if (!cpu_ops[cpu]) {
-		pr_warn("%s: unsupported enable-method property: %s\n",
-			dn->full_name, enable_method);
+		if (acpi_disabled) {
+			pr_warn("%s: unsupported enable-method property: %s\n",
+				dn->full_name, enable_method);
+		} else {
+			pr_warn("CPU %d: boot protocol unsupported or unknown\n",
+				cpu);
+		}
+
 		return -EOPNOTSUPP;
 	}
 
@@ -78,7 +119,14 @@ int __init cpu_read_ops(struct device_node *dn, int cpu)
 
 void __init cpu_read_bootcpu_ops(void)
 {
-	struct device_node *dn = of_get_cpu_node(0, NULL);
+	struct device_node *dn;
+
+	if (!acpi_disabled) {
+		cpu_read_ops(NULL, 0);
+		return;
+	}
+
+	dn = of_get_cpu_node(0, NULL);
 	if (!dn) {
 		pr_err("Failed to find device node for boot cpu\n");
 		return;
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 8f1d37c..e21bbc9 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -315,7 +315,7 @@ static void (*smp_cross_call)(const struct cpumask *, unsigned int);
  * cpu logical map array containing MPIDR values related to logical
  * cpus. Assumes that cpu_logical_map(0) has already been initialized.
  */
-void __init smp_init_cpus(void)
+static void __init of_smp_init_cpus(void)
 {
 	struct device_node *dn = NULL;
 	unsigned int i, cpu = 1;
@@ -418,6 +418,31 @@ next:
 			set_cpu_possible(i, true);
 }
 
+/*
+ * In ACPI mode, the cpu possible map was enumerated before SMP
+ * initialization when MADT table was parsed, so we can get the
+ * possible map here to initialize CPUs.
+ */
+static void __init acpi_smp_init_cpus(void)
+{
+	int cpu;
+
+	for_each_possible_cpu(cpu) {
+		if (cpu_read_ops(NULL, cpu) != 0)
+			continue;
+
+		cpu_ops[cpu]->cpu_init(NULL, cpu);
+	}
+}
+
+void __init smp_init_cpus(void)
+{
+	if (acpi_disabled)
+		of_smp_init_cpus();
+	else
+		acpi_smp_init_cpus();
+}
+
 void __init smp_prepare_cpus(unsigned int max_cpus)
 {
 	int err;
