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 void store_cpu_topology(unsigned int cpuid)
  25 {
  26         struct cpu_topology *cpuid_topo = &cpu_topology[cpuid];
  27         u64 mpidr;
  28
  29         if (cpuid_topo->package_id != -1)
  30                 goto topology_populated;
  31
  32         mpidr = read_cpuid_mpidr();
  33
  34         /* Uniprocessor systems can rely on default topology values */
  35         if (mpidr & MPIDR_UP_BITMASK)
  36                 return;
  37
  38         /* Create cpu topology mapping based on MPIDR. */
  39         if (mpidr & MPIDR_MT_BITMASK) {
  40                 /* Multiprocessor system : Multi-threads per core */
  41                 cpuid_topo->thread_id  = MPIDR_AFFINITY_LEVEL(mpidr, 0);
  42                 cpuid_topo->core_id    = MPIDR_AFFINITY_LEVEL(mpidr, 1);
  43                 cpuid_topo->package_id = MPIDR_AFFINITY_LEVEL(mpidr, 2) |
  44                                          MPIDR_AFFINITY_LEVEL(mpidr, 3) << 8;
  45         } else {
  46                 /* Multiprocessor system : Single-thread per core */
  47                 cpuid_topo->thread_id  = -1;
  48                 cpuid_topo->core_id    = MPIDR_AFFINITY_LEVEL(mpidr, 0);
  49                 cpuid_topo->package_id = MPIDR_AFFINITY_LEVEL(mpidr, 1) |
  50                                          MPIDR_AFFINITY_LEVEL(mpidr, 2) << 8 |
  51                                          MPIDR_AFFINITY_LEVEL(mpidr, 3) << 16;
  52         }
  53
  54         pr_debug("CPU%u: cluster %d core %d thread %d mpidr %#016llx\n",
  55                  cpuid, cpuid_topo->package_id, cpuid_topo->core_id,
  56                  cpuid_topo->thread_id, mpidr);
  57
  58 topology_populated:
  59         update_siblings_masks(cpuid);
  60 }
  61
  62 #ifdef CONFIG_ACPI
  63 static bool __init acpi_cpu_is_threaded(int cpu)
  64 {
  65         int is_threaded = acpi_pptt_cpu_is_thread(cpu);
  66
  67         /*
  68          * if the PPTT doesn't have thread information, assume a homogeneous
  69          * machine and return the current CPU's thread state.
  70          */
  71         if (is_threaded < 0)
  72                 is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK;
  73
  74         return !!is_threaded;
  75 }
  76
  77 /*
  78  * Propagate the topology information of the processor_topology_node tree to the
  79  * cpu_topology array.
  80  */
  81 int __init parse_acpi_topology(void)
  82 {
  83         int cpu, topology_id;
  84
  85         if (acpi_disabled)
  86                 return 0;
  87
  88         for_each_possible_cpu(cpu) {
  89                 int i, cache_id;
  90
  91                 topology_id = find_acpi_cpu_topology(cpu, 0);
  92                 if (topology_id < 0)
  93                         return topology_id;
  94
  95                 if (acpi_cpu_is_threaded(cpu)) {
  96                         cpu_topology[cpu].thread_id = topology_id;
  97                         topology_id = find_acpi_cpu_topology(cpu, 1);
  98                         cpu_topology[cpu].core_id   = topology_id;
  99                 } else {
 100                         cpu_topology[cpu].thread_id  = -1;
 101                         cpu_topology[cpu].core_id    = topology_id;
 102                 }
 103                 topology_id = find_acpi_cpu_topology_package(cpu);
 104                 cpu_topology[cpu].package_id = topology_id;
 105
 106                 i = acpi_find_last_cache_level(cpu);
 107
 108                 if (i > 0) {
 109                         /*
 110                          * this is the only part of cpu_topology that has
 111                          * a direct relationship with the cache topology
 112                          */
 113                         cache_id = find_acpi_cpu_cache_topology(cpu, i);
 114                         if (cache_id > 0)
 115                                 cpu_topology[cpu].llc_id = cache_id;
 116                 }
 117         }
 118
 119         return 0;
 120 }
 121 #endif
 122
 123