arch/arm64/kernel/cpu_ops.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * CPU kernel entry/exit control
   4  *
   5  * Copyright (C) 2013 ARM Ltd.
   6  */
   7
   8 #include <linux/acpi.h>
   9 #include <linux/cache.h>
  10 #include <linux/errno.h>
  11 #include <linux/of.h>
  12 #include <linux/string.h>
  13 #include <asm/acpi.h>
  14 #include <asm/cpu_ops.h>
  15 #include <asm/smp_plat.h>
  16
  17 extern const struct cpu_operations smp_spin_table_ops;
  18 #ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
  19 extern const struct cpu_operations acpi_parking_protocol_ops;
  20 #endif
  21 extern const struct cpu_operations cpu_psci_ops;
  22
  23 static const struct cpu_operations *cpu_ops[NR_CPUS] __ro_after_init;
  24
  25 static const struct cpu_operations *const dt_supported_cpu_ops[] __initconst = {
  26         &smp_spin_table_ops,
  27         &cpu_psci_ops,
  28         NULL,
  29 };
  30
  31 static const struct cpu_operations *const acpi_supported_cpu_ops[] __initconst = {
  32 #ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
  33         &acpi_parking_protocol_ops,
  34 #endif
  35         &cpu_psci_ops,
  36         NULL,
  37 };
  38
  39 static const struct cpu_operations * __init cpu_get_ops(const char *name)
  40 {
  41         const struct cpu_operations *const *ops;
  42
  43         ops = acpi_disabled ? dt_supported_cpu_ops : acpi_supported_cpu_ops;
  44
  45         while (*ops) {
  46                 if (!strcmp(name, (*ops)->name))
  47                         return *ops;
  48
  49                 ops++;
  50         }
  51
  52         return NULL;
  53 }
  54
  55 static const char *__init cpu_read_enable_method(int cpu)
  56 {
  57         const char *enable_method;
  58
  59         if (acpi_disabled) {
  60                 struct device_node *dn = of_get_cpu_node(cpu, NULL);
  61
  62                 if (!dn) {
  63                         if (!cpu)
  64                                 pr_err("Failed to find device node for boot cpu\n");
  65                         return NULL;
  66                 }
  67
  68                 enable_method = of_get_property(dn, "enable-method", NULL);
  69                 if (!enable_method) {
  70                         /*
  71                          * The boot CPU may not have an enable method (e.g.
  72                          * when spin-table is used for secondaries).
  73                          * Don't warn spuriously.
  74                          */
  75                         if (cpu != 0)
  76                                 pr_err("%pOF: missing enable-method property\n",
  77                                         dn);
  78                 }
  79                 of_node_put(dn);
  80         } else {
  81                 enable_method = acpi_get_enable_method(cpu);
  82                 if (!enable_method) {
  83                         /*
  84                          * In ACPI systems the boot CPU does not require
  85                          * checking the enable method since for some
  86                          * boot protocol (ie parking protocol) it need not
  87                          * be initialized. Don't warn spuriously.
  88                          */
  89                         if (cpu != 0)
  90                                 pr_err("Unsupported ACPI enable-method\n");
  91                 }
  92         }
  93
  94         return enable_method;
  95 }
  96 /*
  97  * Read a cpu's enable method and record it in cpu_ops.
  98  */
  99 int __init init_cpu_ops(int cpu)
 100 {
 101         const char *enable_method = cpu_read_enable_method(cpu);
 102
 103         if (!enable_method)
 104                 return -ENODEV;
 105
 106         cpu_ops[cpu] = cpu_get_ops(enable_method);
 107         if (!cpu_ops[cpu]) {
 108                 pr_warn("Unsupported enable-method: %s\n", enable_method);
 109                 return -EOPNOTSUPP;
 110         }
 111
 112         return 0;
 113 }
 114
 115 const struct cpu_operations *get_cpu_ops(int cpu)
 116 {
 117         return cpu_ops[cpu];
 118 }