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/acpi.h>
  15 #include <linux/arch_topology.h>
  16 #include <linux/cacheinfo.h>
  17 #include <linux/init.h>
  18 #include <linux/percpu.h>
  19
  20 #include <asm/cpu.h>
  21 #include <asm/cputype.h>
  22 #include <asm/topology.h>
  23
  24 #ifdef CONFIG_ACPI
  25 static bool __init acpi_cpu_is_threaded(int cpu)
  26 {
  27         int is_threaded = acpi_pptt_cpu_is_thread(cpu);
  28
  29         /*
  30          * if the PPTT doesn't have thread information, assume a homogeneous
  31          * machine and return the current CPU's thread state.
  32          */
  33         if (is_threaded < 0)
  34                 is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK;
  35
  36         return !!is_threaded;
  37 }
  38
  39 /*
  40  * Propagate the topology information of the processor_topology_node tree to the
  41  * cpu_topology array.
  42  */
  43 int __init parse_acpi_topology(void)
  44 {
  45         int cpu, topology_id;
  46
  47         if (acpi_disabled)
  48                 return 0;
  49
  50         for_each_possible_cpu(cpu) {
  51                 int i, cache_id;
  52
  53                 topology_id = find_acpi_cpu_topology(cpu, 0);
  54                 if (topology_id < 0)
  55                         return topology_id;
  56
  57                 if (acpi_cpu_is_threaded(cpu)) {
  58                         cpu_topology[cpu].thread_id = topology_id;
  59                         topology_id = find_acpi_cpu_topology(cpu, 1);
  60                         cpu_topology[cpu].core_id   = topology_id;
  61                 } else {
  62                         cpu_topology[cpu].thread_id  = -1;
  63                         cpu_topology[cpu].core_id    = topology_id;
  64                 }
  65                 topology_id = find_acpi_cpu_topology_package(cpu);
  66                 cpu_topology[cpu].package_id = topology_id;
  67
  68                 i = acpi_find_last_cache_level(cpu);
  69
  70                 if (i > 0) {
  71                         /*
  72                          * this is the only part of cpu_topology that has
  73                          * a direct relationship with the cache topology
  74                          */
  75                         cache_id = find_acpi_cpu_cache_topology(cpu, i);
  76                         if (cache_id > 0)
  77                                 cpu_topology[cpu].llc_id = cache_id;
  78                 }
  79         }
  80
  81         return 0;
  82 }
  83 #endif
  84
  85