개념 설명 전체 · v6.18.37 / arch/arm64/kernel/psci.c

    1 // SPDX-License-Identifier: GPL-2.0-only
    2 /*
    3  *
    4  * Copyright (C) 2013 ARM Limited
    5  *
    6  * Author: Will Deacon <will.deacon@arm.com>
    7  */
    8 
    9 #define pr_fmt(fmt) "psci: " fmt
   10 
   11 #include <linux/init.h>
   12 #include <linux/of.h>
   13 #include <linux/smp.h>
   14 #include <linux/delay.h>
   15 #include <linux/psci.h>
   16 #include <linux/mm.h>
   17 
   18 #include <uapi/linux/psci.h>
   19 
   20 #include <asm/cpu_ops.h>
   21 #include <asm/errno.h>
   22 #include <asm/smp_plat.h>
   23 
   24 static int __init cpu_psci_cpu_init(unsigned int cpu)
   25 {
   26 	return 0;
   27 }
   28 
   29 static int __init cpu_psci_cpu_prepare(unsigned int cpu)
   30 {
   31 	if (!psci_ops.cpu_on) {
   32 		pr_err("no cpu_on method, not booting CPU%d\n", cpu);
   33 		return -ENODEV;
   34 	}
   35 
   36 	return 0;
   37 }
   38 
   39 static int cpu_psci_cpu_boot(unsigned int cpu)
   40 {
   41 	phys_addr_t pa_secondary_entry = __pa_symbol(secondary_entry);
   42 	int err = psci_ops.cpu_on(cpu_logical_map(cpu), pa_secondary_entry);
   43 	if (err && err != -EPERM)
   44 		pr_err("failed to boot CPU%d (%d)\n", cpu, err);
   45 
   46 	return err;
   47 }
   48 
   49 #ifdef CONFIG_HOTPLUG_CPU
   50 static bool cpu_psci_cpu_can_disable(unsigned int cpu)
   51 {
   52 	return !psci_tos_resident_on(cpu);
   53 }
   54 
   55 static int cpu_psci_cpu_disable(unsigned int cpu)
   56 {
   57 	/* Fail early if we don't have CPU_OFF support */
   58 	if (!psci_ops.cpu_off)
   59 		return -EOPNOTSUPP;
   60 
   61 	/* Trusted OS will deny CPU_OFF */
   62 	if (psci_tos_resident_on(cpu))
   63 		return -EPERM;
   64 
   65 	return 0;
   66 }
   67 
   68 static void cpu_psci_cpu_die(unsigned int cpu)
   69 {
   70 	/*
   71 	 * There are no known implementations of PSCI actually using the
   72 	 * power state field, pass a sensible default for now.
   73 	 */
   74 	u32 state = PSCI_POWER_STATE_TYPE_POWER_DOWN <<
   75 		    PSCI_0_2_POWER_STATE_TYPE_SHIFT;
   76 
   77 	psci_ops.cpu_off(state);
   78 }
   79 
   80 static int cpu_psci_cpu_kill(unsigned int cpu)
   81 {
   82 	int err;
   83 	unsigned long start, end;
   84 
   85 	if (!psci_ops.affinity_info)
   86 		return 0;
   87 	/*
   88 	 * cpu_kill could race with cpu_die and we can
   89 	 * potentially end up declaring this cpu undead
   90 	 * while it is dying. So, try again a few times.
   91 	 */
   92 
   93 	start = jiffies;
   94 	end = start + msecs_to_jiffies(100);
   95 	do {
   96 		err = psci_ops.affinity_info(cpu_logical_map(cpu), 0);
   97 		if (err == PSCI_0_2_AFFINITY_LEVEL_OFF) {
   98 			pr_info("CPU%d killed (polled %d ms)\n", cpu,
   99 				jiffies_to_msecs(jiffies - start));
  100 			return 0;
  101 		}
  102 
  103 		usleep_range(100, 1000);
  104 	} while (time_before(jiffies, end));
  105 
  106 	pr_warn("CPU%d may not have shut down cleanly (AFFINITY_INFO reports %d)\n",
  107 			cpu, err);
  108 	return -ETIMEDOUT;
  109 }
  110 #endif
  111 
  112 const struct cpu_operations cpu_psci_ops = {
  113 	.name		= "psci",
  114 	.cpu_init	= cpu_psci_cpu_init,
  115 	.cpu_prepare	= cpu_psci_cpu_prepare,
  116 	.cpu_boot	= cpu_psci_cpu_boot,
  117 #ifdef CONFIG_HOTPLUG_CPU
  118 	.cpu_can_disable = cpu_psci_cpu_can_disable,
  119 	.cpu_disable	= cpu_psci_cpu_disable,
  120 	.cpu_die	= cpu_psci_cpu_die,
  121 	.cpu_kill	= cpu_psci_cpu_kill,
  122 #endif
  123 };
  124