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 <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
  48 extern void secondary_startup(void);
  49
  50 static 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
  59 void __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
  72 int __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
 103 bool __init psci_smp_available(void)
 104 {
 105         /* is cpu_on available at least? */
 106         return (psci_ops.cpu_on != NULL);
 107 }
 108
 109 struct 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 };