arch/arm/kernel/psci_smp.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) 2012 ARM Limited
  12  *
  13  * Author: Will Deacon <will.deacon@arm.com>
  14  */
  15
  16 #include <linux/init.h>
  17 #include <linux/smp.h>
  18 #include <linux/of.h>
  19 #include <linux/delay.h>
  20 #include <linux/psci.h>
  21
  22 #include <uapi/linux/psci.h>
  23
  24 #include <asm/psci.h>
  25 #include <asm/smp_plat.h>
  26
  27 /*
  28  * psci_smp assumes that the following is true about PSCI:
  29  *
  30  * cpu_suspend   Suspend the execution on a CPU
  31  * @state        we don't currently describe affinity levels, so just pass 0.
  32  * @entry_point  the first instruction to be executed on return
  33  * returns 0  success, < 0 on failure
  34  *
  35  * cpu_off       Power down a CPU
  36  * @state        we don't currently describe affinity levels, so just pass 0.
  37  * no return on successful call
  38  *
  39  * cpu_on        Power up a CPU
  40  * @cpuid        cpuid of target CPU, as from MPIDR
  41  * @entry_point  the first instruction to be executed on return
  42  * returns 0  success, < 0 on failure
  43  *
  44  * migrate       Migrate the context to a different CPU
  45  * @cpuid        cpuid of target CPU, as from MPIDR
  46  * returns 0  success, < 0 on failure
  47  *
  48  */
  49
  50 extern void secondary_startup(void);
  51
  52 static int psci_boot_secondary(unsigned int cpu, struct task_struct *idle)
  53 {
  54         if (psci_ops.cpu_on)
  55                 return psci_ops.cpu_on(cpu_logical_map(cpu),
  56                                         virt_to_idmap(&secondary_startup));
  57         return -ENODEV;
  58 }
  59
  60 #ifdef CONFIG_HOTPLUG_CPU
  61 int psci_cpu_disable(unsigned int cpu)
  62 {
  63         /* Fail early if we don't have CPU_OFF support */
  64         if (!psci_ops.cpu_off)
  65                 return -EOPNOTSUPP;
  66
  67         /* Trusted OS will deny CPU_OFF */
  68         if (psci_tos_resident_on(cpu))
  69                 return -EPERM;
  70
  71         return 0;
  72 }
  73
  74 void psci_cpu_die(unsigned int cpu)
  75 {
  76         u32 state = PSCI_POWER_STATE_TYPE_POWER_DOWN <<
  77                     PSCI_0_2_POWER_STATE_TYPE_SHIFT;
  78
  79         if (psci_ops.cpu_off)
  80                 psci_ops.cpu_off(state);
  81
  82         /* We should never return */
  83         panic("psci: cpu %d failed to shutdown\n", cpu);
  84 }
  85
  86 int psci_cpu_kill(unsigned int cpu)
  87 {
  88         int err, i;
  89
  90         if (!psci_ops.affinity_info)
  91                 return 1;
  92         /*
  93          * cpu_kill could race with cpu_die and we can
  94          * potentially end up declaring this cpu undead
  95          * while it is dying. So, try again a few times.
  96          */
  97
  98         for (i = 0; i < 10; i++) {
  99                 err = psci_ops.affinity_info(cpu_logical_map(cpu), 0);
 100                 if (err == PSCI_0_2_AFFINITY_LEVEL_OFF) {
 101                         pr_info("CPU%d killed.\n", cpu);
 102                         return 1;
 103                 }
 104
 105                 msleep(10);
 106                 pr_info("Retrying again to check for CPU kill\n");
 107         }
 108
 109         pr_warn("CPU%d may not have shut down cleanly (AFFINITY_INFO reports %d)\n",
 110                         cpu, err);
 111         /* Make platform_cpu_kill() fail. */
 112         return 0;
 113 }
 114
 115 #endif
 116
 117 bool __init psci_smp_available(void)
 118 {
 119         /* is cpu_on available at least? */
 120         return (psci_ops.cpu_on != NULL);
 121 }
 122
 123 const struct smp_operations psci_smp_ops __initconst = {
 124         .smp_boot_secondary     = psci_boot_secondary,
 125 #ifdef CONFIG_HOTPLUG_CPU
 126         .cpu_disable            = psci_cpu_disable,
 127         .cpu_die                = psci_cpu_die,
 128         .cpu_kill               = psci_cpu_kill,
 129 #endif
 130 };