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