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 acpi_parking_protocol_ops;
  29 extern const struct cpu_operations cpu_psci_ops;
  30
  31 const struct cpu_operations *cpu_ops[NR_CPUS];
  32
  33 static const struct cpu_operations *dt_supported_cpu_ops[] __initconst = {
  34         &smp_spin_table_ops,
  35         &cpu_psci_ops,
  36         NULL,
  37 };
  38
  39 static const struct cpu_operations *acpi_supported_cpu_ops[] __initconst = {
  40 #ifdef CONFIG_ARM64_ACPI_PARKING_PROTOCOL
  41         &acpi_parking_protocol_ops,
  42 #endif
  43         &cpu_psci_ops,
  44         NULL,
  45 };
  46
  47 static const struct cpu_operations * __init cpu_get_ops(const char *name)
  48 {
  49         const struct cpu_operations **ops;
  50
  51         ops = acpi_disabled ? dt_supported_cpu_ops : acpi_supported_cpu_ops;
  52
  53         while (*ops) {
  54                 if (!strcmp(name, (*ops)->name))
  55                         return *ops;
  56
  57                 ops++;
  58         }
  59
  60         return NULL;
  61 }
  62
  63 static const char *__init cpu_read_enable_method(int cpu)
  64 {
  65         const char *enable_method;
  66
  67         if (acpi_disabled) {
  68                 struct device_node *dn = of_get_cpu_node(cpu, NULL);
  69
  70                 if (!dn) {
  71                         if (!cpu)
  72                                 pr_err("Failed to find device node for boot cpu\n");
  73                         return NULL;
  74                 }
  75
  76                 enable_method = of_get_property(dn, "enable-method", NULL);
  77                 if (!enable_method) {
  78                         /*
  79                          * The boot CPU may not have an enable method (e.g.
  80                          * when spin-table is used for secondaries).
  81                          * Don't warn spuriously.
  82                          */
  83                         if (cpu != 0)
  84                                 pr_err("%s: missing enable-method property\n",
  85                                         dn->full_name);
  86                 }
  87         } else {
  88                 enable_method = acpi_get_enable_method(cpu);
  89                 if (!enable_method) {
  90                         /*
  91                          * In ACPI systems the boot CPU does not require
  92                          * checking the enable method since for some
  93                          * boot protocol (ie parking protocol) it need not
  94                          * be initialized. Don't warn spuriously.
  95                          */
  96                         if (cpu != 0)
  97                                 pr_err("Unsupported ACPI enable-method\n");
  98                 }
  99         }
 100
 101         return enable_method;
 102 }
 103 /*
 104  * Read a cpu's enable method and record it in cpu_ops.
 105  */
 106 int __init cpu_read_ops(int cpu)
 107 {
 108         const char *enable_method = cpu_read_enable_method(cpu);
 109
 110         if (!enable_method)
 111                 return -ENODEV;
 112
 113         cpu_ops[cpu] = cpu_get_ops(enable_method);
 114         if (!cpu_ops[cpu]) {
 115                 pr_warn("Unsupported enable-method: %s\n", enable_method);
 116                 return -EOPNOTSUPP;
 117         }
 118
 119         return 0;
 120 }