linux/arch/arm/kernel/psci_smp.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *
   4 * Copyright (C) 2012 ARM Limited
   5 *
   6 * Author: Will Deacon <will.deacon@arm.com>
   7 */
   8
   9#include <linux/init.h>
  10#include <linux/smp.h>
  11#include <linux/of.h>
  12#include <linux/delay.h>
  13#include <linux/psci.h>
  14
  15#include <uapi/linux/psci.h>
  16
  17#include <asm/psci.h>
  18#include <asm/smp_plat.h>
  19
  20/*
  21 * psci_smp assumes that the following is true about PSCI:
  22 *
  23 * cpu_suspend   Suspend the execution on a CPU
  24 * @state        we don't currently describe affinity levels, so just pass 0.
  25 * @entry_point  the first instruction to be executed on return
  26 * returns 0  success, < 0 on failure
  27 *
  28 * cpu_off       Power down a CPU
  29 * @state        we don't currently describe affinity levels, so just pass 0.
  30 * no return on successful call
  31 *
  32 * cpu_on        Power up a CPU
  33 * @cpuid        cpuid of target CPU, as from MPIDR
  34 * @entry_point  the first instruction to be executed on return
  35 * returns 0  success, < 0 on failure
  36 *
  37 * migrate       Migrate the context to a different CPU
  38 * @cpuid        cpuid of target CPU, as from MPIDR
  39 * returns 0  success, < 0 on failure
  40 *
  41 */
  42
  43extern void secondary_startup(void);
  44
  45static int psci_boot_secondary(unsigned int cpu, struct task_struct *idle)
  46{
  47        if (psci_ops.cpu_on)
  48                return psci_ops.cpu_on(cpu_logical_map(cpu),
  49                                        virt_to_idmap(&secondary_startup));
  50        return -ENODEV;
  51}
  52
  53#ifdef CONFIG_HOTPLUG_CPU
  54static int psci_cpu_disable(unsigned int cpu)
  55{
  56        /* Fail early if we don't have CPU_OFF support */
  57        if (!psci_ops.cpu_off)
  58                return -EOPNOTSUPP;
  59
  60        /* Trusted OS will deny CPU_OFF */
  61        if (psci_tos_resident_on(cpu))
  62                return -EPERM;
  63
  64        return 0;
  65}
  66
  67static void psci_cpu_die(unsigned int cpu)
  68{
  69        u32 state = PSCI_POWER_STATE_TYPE_POWER_DOWN <<
  70                    PSCI_0_2_POWER_STATE_TYPE_SHIFT;
  71
  72        if (psci_ops.cpu_off)
  73                psci_ops.cpu_off(state);
  74
  75        /* We should never return */
  76        panic("psci: cpu %d failed to shutdown\n", cpu);
  77}
  78
  79static int psci_cpu_kill(unsigned int cpu)
  80{
  81        int err, i;
  82
  83        if (!psci_ops.affinity_info)
  84                return 1;
  85        /*
  86         * cpu_kill could race with cpu_die and we can
  87         * potentially end up declaring this cpu undead
  88         * while it is dying. So, try again a few times.
  89         */
  90
  91        for (i = 0; i < 10; i++) {
  92                err = psci_ops.affinity_info(cpu_logical_map(cpu), 0);
  93                if (err == PSCI_0_2_AFFINITY_LEVEL_OFF) {
  94                        pr_info("CPU%d killed.\n", cpu);
  95                        return 1;
  96                }
  97
  98                msleep(10);
  99                pr_info("Retrying again to check for CPU kill\n");
 100        }
 101
 102        pr_warn("CPU%d may not have shut down cleanly (AFFINITY_INFO reports %d)\n",
 103                        cpu, err);
 104        /* Make platform_cpu_kill() fail. */
 105        return 0;
 106}
 107
 108#endif
 109
 110bool __init psci_smp_available(void)
 111{
 112        /* is cpu_on available at least? */
 113        return (psci_ops.cpu_on != NULL);
 114}
 115
 116const struct smp_operations psci_smp_ops __initconst = {
 117        .smp_boot_secondary     = psci_boot_secondary,
 118#ifdef CONFIG_HOTPLUG_CPU
 119        .cpu_disable            = psci_cpu_disable,
 120        .cpu_die                = psci_cpu_die,
 121        .cpu_kill               = psci_cpu_kill,
 122#endif
 123};
 124