arch/arm64/kernel/psci.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *
   4  * Copyright (C) 2013 ARM Limited
   5  *
   6  * Author: Will Deacon <will.deacon@arm.com>
   7  */
   8
   9 #define pr_fmt(fmt) "psci: " fmt
  10
  11 #include <linux/init.h>
  12 #include <linux/of.h>
  13 #include <linux/smp.h>
  14 #include <linux/delay.h>
  15 #include <linux/psci.h>
  16 #include <linux/mm.h>
  17
  18 #include <uapi/linux/psci.h>
  19
  20 #include <asm/cpu_ops.h>
  21 #include <asm/errno.h>
  22 #include <asm/smp_plat.h>
  23
  24 static int __init cpu_psci_cpu_init(unsigned int cpu)
  25 {
  26         return 0;
  27 }
  28
  29 static int __init cpu_psci_cpu_prepare(unsigned int cpu)
  30 {
  31         if (!psci_ops.cpu_on) {
  32                 pr_err("no cpu_on method, not booting CPU%d\n", cpu);
  33                 return -ENODEV;
  34         }
  35
  36         return 0;
  37 }
  38
  39 static int cpu_psci_cpu_boot(unsigned int cpu)
  40 {
  41         int err = psci_ops.cpu_on(cpu_logical_map(cpu), __pa_symbol(secondary_entry));
  42         if (err)
  43                 pr_err("failed to boot CPU%d (%d)\n", cpu, err);
  44
  45         return err;
  46 }
  47
  48 #ifdef CONFIG_HOTPLUG_CPU
  49 static bool cpu_psci_cpu_can_disable(unsigned int cpu)
  50 {
  51         return !psci_tos_resident_on(cpu);
  52 }
  53
  54 static int cpu_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
  67 static void cpu_psci_cpu_die(unsigned int cpu)
  68 {
  69         /*
  70          * There are no known implementations of PSCI actually using the
  71          * power state field, pass a sensible default for now.
  72          */
  73         u32 state = PSCI_POWER_STATE_TYPE_POWER_DOWN <<
  74                     PSCI_0_2_POWER_STATE_TYPE_SHIFT;
  75
  76         psci_ops.cpu_off(state);
  77 }
  78
  79 static int cpu_psci_cpu_kill(unsigned int cpu)
  80 {
  81         int err;
  82         unsigned long start, end;
  83
  84         if (!psci_ops.affinity_info)
  85                 return 0;
  86         /*
  87          * cpu_kill could race with cpu_die and we can
  88          * potentially end up declaring this cpu undead
  89          * while it is dying. So, try again a few times.
  90          */
  91
  92         start = jiffies;
  93         end = start + msecs_to_jiffies(100);
  94         do {
  95                 err = psci_ops.affinity_info(cpu_logical_map(cpu), 0);
  96                 if (err == PSCI_0_2_AFFINITY_LEVEL_OFF) {
  97                         pr_info("CPU%d killed (polled %d ms)\n", cpu,
  98                                 jiffies_to_msecs(jiffies - start));
  99                         return 0;
 100                 }
 101
 102                 usleep_range(100, 1000);
 103         } while (time_before(jiffies, end));
 104
 105         pr_warn("CPU%d may not have shut down cleanly (AFFINITY_INFO reports %d)\n",
 106                         cpu, err);
 107         return -ETIMEDOUT;
 108 }
 109 #endif
 110
 111 const struct cpu_operations cpu_psci_ops = {
 112         .name           = "psci",
 113         .cpu_init       = cpu_psci_cpu_init,
 114         .cpu_prepare    = cpu_psci_cpu_prepare,
 115         .cpu_boot       = cpu_psci_cpu_boot,
 116 #ifdef CONFIG_HOTPLUG_CPU
 117         .cpu_can_disable = cpu_psci_cpu_can_disable,
 118         .cpu_disable    = cpu_psci_cpu_disable,
 119         .cpu_die        = cpu_psci_cpu_die,
 120         .cpu_kill       = cpu_psci_cpu_kill,
 121 #endif
 122 };
 123