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 extern const struct cpu_operations acpi_parking_protocol_ops;
  19 extern const struct cpu_operations cpu_psci_ops;
  20
  21 const struct cpu_operations *cpu_ops[NR_CPUS] __ro_after_init;
  22
  23 static const struct cpu_operations *const dt_supported_cpu_ops[] __initconst = {
  24         &smp_spin_table_ops,
  25         &cpu_psci_ops,
  26         NULL,
  27 };
  28
  29 static const struct cpu_operations *const acpi_supported_cpu_ops[] __initconst = {
  30 #ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
  31         &acpi_parking_protocol_ops,
  32 #endif
  33         &cpu_psci_ops,
  34         NULL,
  35 };
  36
  37 static const struct cpu_operations * __init cpu_get_ops(const char *name)
  38 {
  39         const struct cpu_operations *const *ops;
  40
  41         ops = acpi_disabled ? dt_supported_cpu_ops : acpi_supported_cpu_ops;
  42
  43         while (*ops) {
  44                 if (!strcmp(name, (*ops)->name))
  45                         return *ops;
  46
  47                 ops++;
  48         }
  49
  50         return NULL;
  51 }
  52
  53 static const char *__init cpu_read_enable_method(int cpu)
  54 {
  55         const char *enable_method;
  56
  57         if (acpi_disabled) {
  58                 struct device_node *dn = of_get_cpu_node(cpu, NULL);
  59
  60                 if (!dn) {
  61                         if (!cpu)
  62                                 pr_err("Failed to find device node for boot cpu\n");
  63                         return NULL;
  64                 }
  65
  66                 enable_method = of_get_property(dn, "enable-method", NULL);
  67                 if (!enable_method) {
  68                         /*
  69                          * The boot CPU may not have an enable method (e.g.
  70                          * when spin-table is used for secondaries).
  71                          * Don't warn spuriously.
  72                          */
  73                         if (cpu != 0)
  74                                 pr_err("%pOF: missing enable-method property\n",
  75                                         dn);
  76                 }
  77                 of_node_put(dn);
  78         } else {
  79                 enable_method = acpi_get_enable_method(cpu);
  80                 if (!enable_method) {
  81                         /*
  82                          * In ACPI systems the boot CPU does not require
  83                          * checking the enable method since for some
  84                          * boot protocol (ie parking protocol) it need not
  85                          * be initialized. Don't warn spuriously.
  86                          */
  87                         if (cpu != 0)
  88                                 pr_err("Unsupported ACPI enable-method\n");
  89                 }
  90         }
  91
  92         return enable_method;
  93 }
  94 /*
  95  * Read a cpu's enable method and record it in cpu_ops.
  96  */
  97 int __init cpu_read_ops(int cpu)
  98 {
  99         const char *enable_method = cpu_read_enable_method(cpu);
 100
 101         if (!enable_method)
 102                 return -ENODEV;
 103
 104         cpu_ops[cpu] = cpu_get_ops(enable_method);
 105         if (!cpu_ops[cpu]) {
 106                 pr_warn("Unsupported enable-method: %s\n", enable_method);
 107                 return -EOPNOTSUPP;
 108         }
 109
 110         return 0;
 111 }