v4.19.13 snapshot.
diff --git a/arch/arm64/kernel/psci.c b/arch/arm64/kernel/psci.c
new file mode 100644
index 0000000..e8edbf1
--- /dev/null
+++ b/arch/arm64/kernel/psci.c
@@ -0,0 +1,129 @@
+/*
+ * 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.
+ *
+ * Copyright (C) 2013 ARM Limited
+ *
+ * Author: Will Deacon <will.deacon@arm.com>
+ */
+
+#define pr_fmt(fmt) "psci: " fmt
+
+#include <linux/init.h>
+#include <linux/of.h>
+#include <linux/smp.h>
+#include <linux/delay.h>
+#include <linux/psci.h>
+#include <linux/mm.h>
+
+#include <uapi/linux/psci.h>
+
+#include <asm/compiler.h>
+#include <asm/cpu_ops.h>
+#include <asm/errno.h>
+#include <asm/smp_plat.h>
+
+static int __init cpu_psci_cpu_init(unsigned int cpu)
+{
+ return 0;
+}
+
+static int __init cpu_psci_cpu_prepare(unsigned int cpu)
+{
+ if (!psci_ops.cpu_on) {
+ pr_err("no cpu_on method, not booting CPU%d\n", cpu);
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
+static int cpu_psci_cpu_boot(unsigned int cpu)
+{
+ int err = psci_ops.cpu_on(cpu_logical_map(cpu), __pa_symbol(secondary_entry));
+ if (err)
+ pr_err("failed to boot CPU%d (%d)\n", cpu, err);
+
+ return err;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static int cpu_psci_cpu_disable(unsigned int cpu)
+{
+ /* Fail early if we don't have CPU_OFF support */
+ if (!psci_ops.cpu_off)
+ return -EOPNOTSUPP;
+
+ /* Trusted OS will deny CPU_OFF */
+ if (psci_tos_resident_on(cpu))
+ return -EPERM;
+
+ return 0;
+}
+
+static void cpu_psci_cpu_die(unsigned int cpu)
+{
+ int ret;
+ /*
+ * There are no known implementations of PSCI actually using the
+ * power state field, pass a sensible default for now.
+ */
+ u32 state = PSCI_POWER_STATE_TYPE_POWER_DOWN <<
+ PSCI_0_2_POWER_STATE_TYPE_SHIFT;
+
+ ret = psci_ops.cpu_off(state);
+
+ pr_crit("unable to power off CPU%u (%d)\n", cpu, ret);
+}
+
+static int cpu_psci_cpu_kill(unsigned int cpu)
+{
+ int err, i;
+
+ if (!psci_ops.affinity_info)
+ return 0;
+ /*
+ * cpu_kill could race with cpu_die and we can
+ * potentially end up declaring this cpu undead
+ * while it is dying. So, try again a few times.
+ */
+
+ for (i = 0; i < 10; i++) {
+ err = psci_ops.affinity_info(cpu_logical_map(cpu), 0);
+ if (err == PSCI_0_2_AFFINITY_LEVEL_OFF) {
+ pr_info("CPU%d killed.\n", cpu);
+ return 0;
+ }
+
+ msleep(10);
+ pr_info("Retrying again to check for CPU kill\n");
+ }
+
+ pr_warn("CPU%d may not have shut down cleanly (AFFINITY_INFO reports %d)\n",
+ cpu, err);
+ return -ETIMEDOUT;
+}
+#endif
+
+const struct cpu_operations cpu_psci_ops = {
+ .name = "psci",
+#ifdef CONFIG_CPU_IDLE
+ .cpu_init_idle = psci_cpu_init_idle,
+ .cpu_suspend = psci_cpu_suspend_enter,
+#endif
+ .cpu_init = cpu_psci_cpu_init,
+ .cpu_prepare = cpu_psci_cpu_prepare,
+ .cpu_boot = cpu_psci_cpu_boot,
+#ifdef CONFIG_HOTPLUG_CPU
+ .cpu_disable = cpu_psci_cpu_disable,
+ .cpu_die = cpu_psci_cpu_die,
+ .cpu_kill = cpu_psci_cpu_kill,
+#endif
+};
+