1 /* 2 * arch/arm/kernel/topology.c 3 * 4 * Copyright (C) 2011 Linaro Limited. 5 * Written by: Vincent Guittot 6 * 7 * based on 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/cputype.h> 23 #include <asm/topology.h> 24 25 #define MPIDR_SMP_BITMASK (0x3 << 30) 26 #define MPIDR_SMP_VALUE (0x2 << 30) 27 28 #define MPIDR_MT_BITMASK (0x1 << 24) 29 30 /* 31 * These masks reflect the current use of the affinity levels. 32 * The affinity level can be up to 16 bits according to ARM ARM 33 */ 34 35 #define MPIDR_LEVEL0_MASK 0x3 36 #define MPIDR_LEVEL0_SHIFT 0 37 38 #define MPIDR_LEVEL1_MASK 0xF 39 #define MPIDR_LEVEL1_SHIFT 8 40 41 #define MPIDR_LEVEL2_MASK 0xFF 42 #define MPIDR_LEVEL2_SHIFT 16 43 44 struct cputopo_arm cpu_topology[NR_CPUS]; 45 46 const struct cpumask *cpu_coregroup_mask(int cpu) 47 { 48 return &cpu_topology[cpu].core_sibling; 49 } 50 51 /* 52 * store_cpu_topology is called at boot when only one cpu is running 53 * and with the mutex cpu_hotplug.lock locked, when several cpus have booted, 54 * which prevents simultaneous write access to cpu_topology array 55 */ 56 void store_cpu_topology(unsigned int cpuid) 57 { 58 struct cputopo_arm *cpuid_topo = &cpu_topology[cpuid]; 59 unsigned int mpidr; 60 unsigned int cpu; 61 62 /* If the cpu topology has been already set, just return */ 63 if (cpuid_topo->core_id != -1) 64 return; 65 66 mpidr = read_cpuid_mpidr(); 67 68 /* create cpu topology mapping */ 69 if ((mpidr & MPIDR_SMP_BITMASK) == MPIDR_SMP_VALUE) { 70 /* 71 * This is a multiprocessor system 72 * multiprocessor format & multiprocessor mode field are set 73 */ 74 75 if (mpidr & MPIDR_MT_BITMASK) { 76 /* core performance interdependency */ 77 cpuid_topo->thread_id = (mpidr >> MPIDR_LEVEL0_SHIFT) 78 & MPIDR_LEVEL0_MASK; 79 cpuid_topo->core_id = (mpidr >> MPIDR_LEVEL1_SHIFT) 80 & MPIDR_LEVEL1_MASK; 81 cpuid_topo->socket_id = (mpidr >> MPIDR_LEVEL2_SHIFT) 82 & MPIDR_LEVEL2_MASK; 83 } else { 84 /* largely independent cores */ 85 cpuid_topo->thread_id = -1; 86 cpuid_topo->core_id = (mpidr >> MPIDR_LEVEL0_SHIFT) 87 & MPIDR_LEVEL0_MASK; 88 cpuid_topo->socket_id = (mpidr >> MPIDR_LEVEL1_SHIFT) 89 & MPIDR_LEVEL1_MASK; 90 } 91 } else { 92 /* 93 * This is an uniprocessor system 94 * we are in multiprocessor format but uniprocessor system 95 * or in the old uniprocessor format 96 */ 97 cpuid_topo->thread_id = -1; 98 cpuid_topo->core_id = 0; 99 cpuid_topo->socket_id = -1; 100 } 101 102 /* update core and thread sibling masks */ 103 for_each_possible_cpu(cpu) { 104 struct cputopo_arm *cpu_topo = &cpu_topology[cpu]; 105 106 if (cpuid_topo->socket_id == cpu_topo->socket_id) { 107 cpumask_set_cpu(cpuid, &cpu_topo->core_sibling); 108 if (cpu != cpuid) 109 cpumask_set_cpu(cpu, 110 &cpuid_topo->core_sibling); 111 112 if (cpuid_topo->core_id == cpu_topo->core_id) { 113 cpumask_set_cpu(cpuid, 114 &cpu_topo->thread_sibling); 115 if (cpu != cpuid) 116 cpumask_set_cpu(cpu, 117 &cpuid_topo->thread_sibling); 118 } 119 } 120 } 121 smp_wmb(); 122 123 printk(KERN_INFO "CPU%u: thread %d, cpu %d, socket %d, mpidr %x\n", 124 cpuid, cpu_topology[cpuid].thread_id, 125 cpu_topology[cpuid].core_id, 126 cpu_topology[cpuid].socket_id, mpidr); 127 } 128 129 /* 130 * init_cpu_topology is called at boot when only one cpu is running 131 * which prevent simultaneous write access to cpu_topology array 132 */ 133 void init_cpu_topology(void) 134 { 135 unsigned int cpu; 136 137 /* init core mask */ 138 for_each_possible_cpu(cpu) { 139 struct cputopo_arm *cpu_topo = &(cpu_topology[cpu]); 140 141 cpu_topo->thread_id = -1; 142 cpu_topo->core_id = -1; 143 cpu_topo->socket_id = -1; 144 cpumask_clear(&cpu_topo->core_sibling); 145 cpumask_clear(&cpu_topo->thread_sibling); 146 } 147 smp_wmb(); 148 } 149