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
  24 #include <uapi/linux/psci.h>
  25
  26 #include <asm/compiler.h>
  27 #include <asm/cpu_ops.h>
  28 #include <asm/errno.h>
  29 #include <asm/smp_plat.h>
  30
  31 static int __init cpu_psci_cpu_init(unsigned int cpu)
  32 {
  33         return 0;
  34 }
  35
  36 static int __init cpu_psci_cpu_prepare(unsigned int cpu)
  37 {
  38         if (!psci_ops.cpu_on) {
  39                 pr_err("no cpu_on method, not booting CPU%d\n", cpu);
  40                 return -ENODEV;
  41         }
  42
  43         return 0;
  44 }
  45
  46 static int cpu_psci_cpu_boot(unsigned int cpu)
  47 {
  48         int err = psci_ops.cpu_on(cpu_logical_map(cpu), __pa(secondary_entry));
  49         if (err)
  50                 pr_err("failed to boot CPU%d (%d)\n", cpu, err);
  51
  52         return err;
  53 }
  54
  55 #ifdef CONFIG_HOTPLUG_CPU
  56 static int cpu_psci_cpu_disable(unsigned int cpu)
  57 {
  58         /* Fail early if we don't have CPU_OFF support */
  59         if (!psci_ops.cpu_off)
  60                 return -EOPNOTSUPP;
  61
  62         /* Trusted OS will deny CPU_OFF */
  63         if (psci_tos_resident_on(cpu))
  64                 return -EPERM;
  65
  66         return 0;
  67 }
  68
  69 static void cpu_psci_cpu_die(unsigned int cpu)
  70 {
  71         int ret;
  72         /*
  73          * There are no known implementations of PSCI actually using the
  74          * power state field, pass a sensible default for now.
  75          */
  76         u32 state = PSCI_POWER_STATE_TYPE_POWER_DOWN <<
  77                     PSCI_0_2_POWER_STATE_TYPE_SHIFT;
  78
  79         ret = psci_ops.cpu_off(state);
  80
  81         pr_crit("unable to power off CPU%u (%d)\n", cpu, ret);
  82 }
  83
  84 static int cpu_psci_cpu_kill(unsigned int cpu)
  85 {
  86         int err, i;
  87
  88         if (!psci_ops.affinity_info)
  89                 return 0;
  90         /*
  91          * cpu_kill could race with cpu_die and we can
  92          * potentially end up declaring this cpu undead
  93          * while it is dying. So, try again a few times.
  94          */
  95
  96         for (i = 0; i < 10; i++) {
  97                 err = psci_ops.affinity_info(cpu_logical_map(cpu), 0);
  98                 if (err == PSCI_0_2_AFFINITY_LEVEL_OFF) {
  99                         pr_info("CPU%d killed.\n", cpu);
 100                         return 0;
 101                 }
 102
 103                 msleep(10);
 104                 pr_info("Retrying again to check for CPU kill\n");
 105         }
 106
 107         pr_warn("CPU%d may not have shut down cleanly (AFFINITY_INFO reports %d)\n",
 108                         cpu, err);
 109         return -ETIMEDOUT;
 110 }
 111 #endif
 112
 113 const struct cpu_operations cpu_psci_ops = {
 114         .name           = "psci",
 115 #ifdef CONFIG_CPU_IDLE
 116         .cpu_init_idle  = psci_cpu_init_idle,
 117         .cpu_suspend    = psci_cpu_suspend_enter,
 118 #endif
 119         .cpu_init       = cpu_psci_cpu_init,
 120         .cpu_prepare    = cpu_psci_cpu_prepare,
 121         .cpu_boot       = cpu_psci_cpu_boot,
 122 #ifdef CONFIG_HOTPLUG_CPU
 123         .cpu_disable    = cpu_psci_cpu_disable,
 124         .cpu_die        = cpu_psci_cpu_die,
 125         .cpu_kill       = cpu_psci_cpu_kill,
 126 #endif
 127 };
 128