arch/arm64/kernel/cpu_ops.c

   1 /*
   2  * CPU kernel entry/exit control
   3  *
   4  * Copyright (C) 2013 ARM Ltd.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include <linux/acpi.h>
  20 #include <linux/cache.h>
  21 #include <linux/errno.h>
  22 #include <linux/of.h>
  23 #include <linux/string.h>
  24 #include <asm/acpi.h>
  25 #include <asm/cpu_ops.h>
  26 #include <asm/smp_plat.h>
  27
  28 extern const struct cpu_operations smp_spin_table_ops;
  29 extern const struct cpu_operations acpi_parking_protocol_ops;
  30 extern const struct cpu_operations cpu_psci_ops;
  31
  32 const struct cpu_operations *cpu_ops[NR_CPUS] __ro_after_init;
  33
  34 static const struct cpu_operations *const dt_supported_cpu_ops[] __initconst = {
  35         &smp_spin_table_ops,
  36         &cpu_psci_ops,
  37         NULL,
  38 };
  39
  40 static const struct cpu_operations *const acpi_supported_cpu_ops[] __initconst = {
  41 #ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
  42         &acpi_parking_protocol_ops,
  43 #endif
  44         &cpu_psci_ops,
  45         NULL,
  46 };
  47
  48 static const struct cpu_operations * __init cpu_get_ops(const char *name)
  49 {
  50         const struct cpu_operations *const *ops;
  51
  52         ops = acpi_disabled ? dt_supported_cpu_ops : acpi_supported_cpu_ops;
  53
  54         while (*ops) {
  55                 if (!strcmp(name, (*ops)->name))
  56                         return *ops;
  57
  58                 ops++;
  59         }
  60
  61         return NULL;
  62 }
  63
  64 static const char *__init cpu_read_enable_method(int cpu)
  65 {
  66         const char *enable_method;
  67
  68         if (acpi_disabled) {
  69                 struct device_node *dn = of_get_cpu_node(cpu, NULL);
  70
  71                 if (!dn) {
  72                         if (!cpu)
  73                                 pr_err("Failed to find device node for boot cpu\n");
  74                         return NULL;
  75                 }
  76
  77                 enable_method = of_get_property(dn, "enable-method", NULL);
  78                 if (!enable_method) {
  79                         /*
  80                          * The boot CPU may not have an enable method (e.g.
  81                          * when spin-table is used for secondaries).
  82                          * Don't warn spuriously.
  83                          */
  84                         if (cpu != 0)
  85                                 pr_err("%pOF: missing enable-method property\n",
  86                                         dn);
  87                 }
  88         } else {
  89                 enable_method = acpi_get_enable_method(cpu);
  90                 if (!enable_method) {
  91                         /*
  92                          * In ACPI systems the boot CPU does not require
  93                          * checking the enable method since for some
  94                          * boot protocol (ie parking protocol) it need not
  95                          * be initialized. Don't warn spuriously.
  96                          */
  97                         if (cpu != 0)
  98                                 pr_err("Unsupported ACPI enable-method\n");
  99                 }
 100         }
 101
 102         return enable_method;
 103 }
 104 /*
 105  * Read a cpu's enable method and record it in cpu_ops.
 106  */
 107 int __init cpu_read_ops(int cpu)
 108 {
 109         const char *enable_method = cpu_read_enable_method(cpu);
 110
 111         if (!enable_method)
 112                 return -ENODEV;
 113
 114         cpu_ops[cpu] = cpu_get_ops(enable_method);
 115         if (!cpu_ops[cpu]) {
 116                 pr_warn("Unsupported enable-method: %s\n", enable_method);
 117                 return -EOPNOTSUPP;
 118         }
 119
 120         return 0;
 121 }