v4.19.13 snapshot.
diff --git a/arch/arm64/kernel/cpu_ops.c b/arch/arm64/kernel/cpu_ops.c
new file mode 100644
index 0000000..ea00124
--- /dev/null
+++ b/arch/arm64/kernel/cpu_ops.c
@@ -0,0 +1,121 @@
+/*
+ * CPU kernel entry/exit control
+ *
+ * Copyright (C) 2013 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/acpi.h>
+#include <linux/cache.h>
+#include <linux/errno.h>
+#include <linux/of.h>
+#include <linux/string.h>
+#include <asm/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 acpi_parking_protocol_ops;
+extern const struct cpu_operations cpu_psci_ops;
+
+const struct cpu_operations *cpu_ops[NR_CPUS] __ro_after_init;
+
+static const struct cpu_operations *const dt_supported_cpu_ops[] __initconst = {
+ &smp_spin_table_ops,
+ &cpu_psci_ops,
+ NULL,
+};
+
+static const struct cpu_operations *const acpi_supported_cpu_ops[] __initconst = {
+#ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
+ &acpi_parking_protocol_ops,
+#endif
+ &cpu_psci_ops,
+ NULL,
+};
+
+static const struct cpu_operations * __init cpu_get_ops(const char *name)
+{
+ const struct cpu_operations *const *ops;
+
+ ops = acpi_disabled ? dt_supported_cpu_ops : acpi_supported_cpu_ops;
+
+ while (*ops) {
+ if (!strcmp(name, (*ops)->name))
+ return *ops;
+
+ ops++;
+ }
+
+ return NULL;
+}
+
+static const char *__init cpu_read_enable_method(int cpu)
+{
+ const char *enable_method;
+
+ if (acpi_disabled) {
+ struct device_node *dn = of_get_cpu_node(cpu, NULL);
+
+ if (!dn) {
+ if (!cpu)
+ pr_err("Failed to find device node for boot cpu\n");
+ return NULL;
+ }
+
+ enable_method = of_get_property(dn, "enable-method", NULL);
+ if (!enable_method) {
+ /*
+ * The boot CPU may not have an enable method (e.g.
+ * when spin-table is used for secondaries).
+ * Don't warn spuriously.
+ */
+ if (cpu != 0)
+ pr_err("%pOF: missing enable-method property\n",
+ dn);
+ }
+ } else {
+ enable_method = acpi_get_enable_method(cpu);
+ if (!enable_method) {
+ /*
+ * In ACPI systems the boot CPU does not require
+ * checking the enable method since for some
+ * boot protocol (ie parking protocol) it need not
+ * be initialized. Don't warn spuriously.
+ */
+ if (cpu != 0)
+ pr_err("Unsupported ACPI enable-method\n");
+ }
+ }
+
+ return enable_method;
+}
+/*
+ * Read a cpu's enable method and record it in cpu_ops.
+ */
+int __init cpu_read_ops(int cpu)
+{
+ const char *enable_method = cpu_read_enable_method(cpu);
+
+ if (!enable_method)
+ return -ENODEV;
+
+ cpu_ops[cpu] = cpu_get_ops(enable_method);
+ if (!cpu_ops[cpu]) {
+ pr_warn("Unsupported enable-method: %s\n", enable_method);
+ return -EOPNOTSUPP;
+ }
+
+ return 0;
+}