arch/arm64/kernel/topology.c

   1 /*
   2  * arch/arm64/kernel/topology.c
   3  *
   4  * Copyright (C) 2011,2013,2014 Linaro Limited.
   5  *
   6  * Based on the arm32 version written by Vincent Guittot in turn based on
   7  * arch/sh/kernel/topology.c
   8  *
   9  * This file is subject to the terms and conditions of the GNU General Public
  10  * License.  See the file "COPYING" in the main directory of this archive
  11  * for more details.
  12  */
  13
  14 #include <linux/cpu.h>
  15 #include <linux/cpumask.h>
  16 #include <linux/init.h>
  17 #include <linux/percpu.h>
  18 #include <linux/node.h>
  19 #include <linux/nodemask.h>
  20 #include <linux/sched.h>
  21
  22 #include <asm/topology.h>
  23
  24 /*
  25  * cpu topology table
  26  */
  27 struct cpu_topology cpu_topology[NR_CPUS];
  28 EXPORT_SYMBOL_GPL(cpu_topology);
  29
  30 const struct cpumask *cpu_coregroup_mask(int cpu)
  31 {
  32         return &cpu_topology[cpu].core_sibling;
  33 }
  34
  35 static void update_siblings_masks(unsigned int cpuid)
  36 {
  37         struct cpu_topology *cpu_topo, *cpuid_topo = &cpu_topology[cpuid];
  38         int cpu;
  39
  40         if (cpuid_topo->cluster_id == -1) {
  41                 /*
  42                  * DT does not contain topology information for this cpu
  43                  * reset it to default behaviour
  44                  */
  45                 pr_debug("CPU%u: No topology information configured\n", cpuid);
  46                 cpuid_topo->core_id = 0;
  47                 cpumask_set_cpu(cpuid, &cpuid_topo->core_sibling);
  48                 cpumask_set_cpu(cpuid, &cpuid_topo->thread_sibling);
  49                 return;
  50         }
  51
  52         /* update core and thread sibling masks */
  53         for_each_possible_cpu(cpu) {
  54                 cpu_topo = &cpu_topology[cpu];
  55
  56                 if (cpuid_topo->cluster_id != cpu_topo->cluster_id)
  57                         continue;
  58
  59                 cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
  60                 if (cpu != cpuid)
  61                         cpumask_set_cpu(cpu, &cpuid_topo->core_sibling);
  62
  63                 if (cpuid_topo->core_id != cpu_topo->core_id)
  64                         continue;
  65
  66                 cpumask_set_cpu(cpuid, &cpu_topo->thread_sibling);
  67                 if (cpu != cpuid)
  68                         cpumask_set_cpu(cpu, &cpuid_topo->thread_sibling);
  69         }
  70 }
  71
  72 void store_cpu_topology(unsigned int cpuid)
  73 {
  74         update_siblings_masks(cpuid);
  75 }
  76
  77 /*
  78  * init_cpu_topology is called at boot when only one cpu is running
  79  * which prevent simultaneous write access to cpu_topology array
  80  */
  81 void __init init_cpu_topology(void)
  82 {
  83         unsigned int cpu;
  84
  85         /* init core mask and power*/
  86         for_each_possible_cpu(cpu) {
  87                 struct cpu_topology *cpu_topo = &cpu_topology[cpu];
  88
  89                 cpu_topo->thread_id = -1;
  90                 cpu_topo->core_id =  -1;
  91                 cpu_topo->cluster_id = -1;
  92                 cpumask_clear(&cpu_topo->core_sibling);
  93                 cpumask_clear(&cpu_topo->thread_sibling);
  94         }
  95 }