LXR linux/arch/arm/kernel/psci

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