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