arch/arm64/kernel/psci.c

   1 /*
   2  * This program is free software; you can redistribute it and/or modify
   3  * it under the terms of the GNU General Public License version 2 as
   4  * published by the Free Software Foundation.
   5  *
   6  * This program is distributed in the hope that it will be useful,
   7  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   8  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   9  * GNU General Public License for more details.
  10  *
  11  * Copyright (C) 2013 ARM Limited
  12  *
  13  * Author: Will Deacon <will.deacon@arm.com>
  14  */
  15
  16 #define pr_fmt(fmt) "psci: " fmt
  17
  18 #include <linux/init.h>
  19 #include <linux/of.h>
  20 #include <linux/smp.h>
  21 #include <linux/delay.h>
  22 #include <linux/psci.h>
  23 #include <linux/mm.h>
  24
  25 #include <uapi/linux/psci.h>
  26
  27 #include <asm/compiler.h>
  28 #include <asm/cpu_ops.h>
  29 #include <asm/errno.h>
  30 #include <asm/smp_plat.h>
  31
  32 static int __init cpu_psci_cpu_init(unsigned int cpu)
  33 {
  34         return 0;
  35 }
  36
  37 static int __init cpu_psci_cpu_prepare(unsigned int cpu)
  38 {
  39         if (!psci_ops.cpu_on) {
  40                 pr_err("no cpu_on method, not booting CPU%d\n", cpu);
  41                 return -ENODEV;
  42         }
  43
  44         return 0;
  45 }
  46
  47 static int cpu_psci_cpu_boot(unsigned int cpu)
  48 {
  49         int err = psci_ops.cpu_on(cpu_logical_map(cpu), __pa_symbol(secondary_entry));
  50         if (err)
  51                 pr_err("failed to boot CPU%d (%d)\n", cpu, err);
  52
  53         return err;
  54 }
  55
  56 #ifdef CONFIG_HOTPLUG_CPU
  57 static int cpu_psci_cpu_disable(unsigned int cpu)
  58 {
  59         /* Fail early if we don't have CPU_OFF support */
  60         if (!psci_ops.cpu_off)
  61                 return -EOPNOTSUPP;
  62
  63         /* Trusted OS will deny CPU_OFF */
  64         if (psci_tos_resident_on(cpu))
  65                 return -EPERM;
  66
  67         return 0;
  68 }
  69
  70 static void cpu_psci_cpu_die(unsigned int cpu)
  71 {
  72         int ret;
  73         /*
  74          * There are no known implementations of PSCI actually using the
  75          * power state field, pass a sensible default for now.
  76          */
  77         u32 state = PSCI_POWER_STATE_TYPE_POWER_DOWN <<
  78                     PSCI_0_2_POWER_STATE_TYPE_SHIFT;
  79
  80         ret = psci_ops.cpu_off(state);
  81
  82         pr_crit("unable to power off CPU%u (%d)\n", cpu, ret);
  83 }
  84
  85 static int cpu_psci_cpu_kill(unsigned int cpu)
  86 {
  87         int err, i;
  88
  89         if (!psci_ops.affinity_info)
  90                 return 0;
  91         /*
  92          * cpu_kill could race with cpu_die and we can
  93          * potentially end up declaring this cpu undead
  94          * while it is dying. So, try again a few times.
  95          */
  96
  97         for (i = 0; i < 10; i++) {
  98                 err = psci_ops.affinity_info(cpu_logical_map(cpu), 0);
  99                 if (err == PSCI_0_2_AFFINITY_LEVEL_OFF) {
 100                         pr_info("CPU%d killed.\n", cpu);
 101                         return 0;
 102                 }
 103
 104                 msleep(10);
 105                 pr_info("Retrying again to check for CPU kill\n");
 106         }
 107
 108         pr_warn("CPU%d may not have shut down cleanly (AFFINITY_INFO reports %d)\n",
 109                         cpu, err);
 110         return -ETIMEDOUT;
 111 }
 112 #endif
 113
 114 const struct cpu_operations cpu_psci_ops = {
 115         .name           = "psci",
 116 #ifdef CONFIG_CPU_IDLE
 117         .cpu_init_idle  = psci_cpu_init_idle,
 118         .cpu_suspend    = psci_cpu_suspend_enter,
 119 #endif
 120         .cpu_init       = cpu_psci_cpu_init,
 121         .cpu_prepare    = cpu_psci_cpu_prepare,
 122         .cpu_boot       = cpu_psci_cpu_boot,
 123 #ifdef CONFIG_HOTPLUG_CPU
 124         .cpu_disable    = cpu_psci_cpu_disable,
 125         .cpu_die        = cpu_psci_cpu_die,
 126         .cpu_kill       = cpu_psci_cpu_kill,
 127 #endif
 128 };
 129