v4.19.13 snapshot.
diff --git a/arch/arm/kernel/psci_smp.c b/arch/arm/kernel/psci_smp.c
new file mode 100644
index 0000000..cb3fcae
--- /dev/null
+++ b/arch/arm/kernel/psci_smp.c
@@ -0,0 +1,130 @@
+/*
+ * 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) 2012 ARM Limited
+ *
+ * Author: Will Deacon <will.deacon@arm.com>
+ */
+
+#include <linux/init.h>
+#include <linux/smp.h>
+#include <linux/of.h>
+#include <linux/delay.h>
+#include <linux/psci.h>
+
+#include <uapi/linux/psci.h>
+
+#include <asm/psci.h>
+#include <asm/smp_plat.h>
+
+/*
+ * psci_smp assumes that the following is true about PSCI:
+ *
+ * cpu_suspend Suspend the execution on a CPU
+ * @state we don't currently describe affinity levels, so just pass 0.
+ * @entry_point the first instruction to be executed on return
+ * returns 0 success, < 0 on failure
+ *
+ * cpu_off Power down a CPU
+ * @state we don't currently describe affinity levels, so just pass 0.
+ * no return on successful call
+ *
+ * cpu_on Power up a CPU
+ * @cpuid cpuid of target CPU, as from MPIDR
+ * @entry_point the first instruction to be executed on return
+ * returns 0 success, < 0 on failure
+ *
+ * migrate Migrate the context to a different CPU
+ * @cpuid cpuid of target CPU, as from MPIDR
+ * returns 0 success, < 0 on failure
+ *
+ */
+
+extern void secondary_startup(void);
+
+static int psci_boot_secondary(unsigned int cpu, struct task_struct *idle)
+{
+ if (psci_ops.cpu_on)
+ return psci_ops.cpu_on(cpu_logical_map(cpu),
+ virt_to_idmap(&secondary_startup));
+ return -ENODEV;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+int 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;
+}
+
+void psci_cpu_die(unsigned int cpu)
+{
+ u32 state = PSCI_POWER_STATE_TYPE_POWER_DOWN <<
+ PSCI_0_2_POWER_STATE_TYPE_SHIFT;
+
+ if (psci_ops.cpu_off)
+ psci_ops.cpu_off(state);
+
+ /* We should never return */
+ panic("psci: cpu %d failed to shutdown\n", cpu);
+}
+
+int psci_cpu_kill(unsigned int cpu)
+{
+ int err, i;
+
+ if (!psci_ops.affinity_info)
+ return 1;
+ /*
+ * 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 1;
+ }
+
+ 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);
+ /* Make platform_cpu_kill() fail. */
+ return 0;
+}
+
+#endif
+
+bool __init psci_smp_available(void)
+{
+ /* is cpu_on available at least? */
+ return (psci_ops.cpu_on != NULL);
+}
+
+const struct smp_operations psci_smp_ops __initconst = {
+ .smp_boot_secondary = psci_boot_secondary,
+#ifdef CONFIG_HOTPLUG_CPU
+ .cpu_disable = psci_cpu_disable,
+ .cpu_die = psci_cpu_die,
+ .cpu_kill = psci_cpu_kill,
+#endif
+};