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 <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
  50extern void secondary_startup(void);
  51
  52static 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
  61int 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
  74void 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
  86int 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
 117bool __init psci_smp_available(void)
 118{
 119        /* is cpu_on available at least? */
 120        return (psci_ops.cpu_on != NULL);
 121}
 122
 123const 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};
 131