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/export.h>
17 #include <linux/init.h>
18 #include <linux/percpu.h>
19 #include <linux/node.h>
20 #include <linux/nodemask.h>
21 #include <linux/sched.h>
22
23 #include <asm/cputype.h>
24 #include <asm/topology.h>
25
26 #define MPIDR_SMP_BITMASK (0x3 << 30)
27 #define MPIDR_SMP_VALUE (0x2 << 30)
28
29 #define MPIDR_MT_BITMASK (0x1 << 24)
30
31 /*
32 * These masks reflect the current use of the affinity levels.
33 * The affinity level can be up to 16 bits according to ARM ARM
34 */
35
36 #define MPIDR_LEVEL0_MASK 0x3
37 #define MPIDR_LEVEL0_SHIFT 0
38
39 #define MPIDR_LEVEL1_MASK 0xF
40 #define MPIDR_LEVEL1_SHIFT 8
41
42 #define MPIDR_LEVEL2_MASK 0xFF
43 #define MPIDR_LEVEL2_SHIFT 16
44
45 struct cputopo_arm cpu_topology[NR_CPUS];
46 EXPORT_SYMBOL_GPL(cpu_topology);
47
cpu_coregroup_mask(int cpu)48 const struct cpumask *cpu_coregroup_mask(int cpu)
49 {
50 return &cpu_topology[cpu].core_sibling;
51 }
52
53 /*
54 * store_cpu_topology is called at boot when only one cpu is running
55 * and with the mutex cpu_hotplug.lock locked, when several cpus have booted,
56 * which prevents simultaneous write access to cpu_topology array
57 */
store_cpu_topology(unsigned int cpuid)58 void store_cpu_topology(unsigned int cpuid)
59 {
60 struct cputopo_arm *cpuid_topo = &cpu_topology[cpuid];
61 unsigned int mpidr;
62 unsigned int cpu;
63
64 /* If the cpu topology has been already set, just return */
65 if (cpuid_topo->core_id != -1)
66 return;
67
68 mpidr = read_cpuid_mpidr();
69
70 /* create cpu topology mapping */
71 if ((mpidr & MPIDR_SMP_BITMASK) == MPIDR_SMP_VALUE) {
72 /*
73 * This is a multiprocessor system
74 * multiprocessor format & multiprocessor mode field are set
75 */
76
77 if (mpidr & MPIDR_MT_BITMASK) {
78 /* core performance interdependency */
79 cpuid_topo->thread_id = (mpidr >> MPIDR_LEVEL0_SHIFT)
80 & MPIDR_LEVEL0_MASK;
81 cpuid_topo->core_id = (mpidr >> MPIDR_LEVEL1_SHIFT)
82 & MPIDR_LEVEL1_MASK;
83 cpuid_topo->socket_id = (mpidr >> MPIDR_LEVEL2_SHIFT)
84 & MPIDR_LEVEL2_MASK;
85 } else {
86 /* largely independent cores */
87 cpuid_topo->thread_id = -1;
88 cpuid_topo->core_id = (mpidr >> MPIDR_LEVEL0_SHIFT)
89 & MPIDR_LEVEL0_MASK;
90 cpuid_topo->socket_id = (mpidr >> MPIDR_LEVEL1_SHIFT)
91 & MPIDR_LEVEL1_MASK;
92 }
93 } else {
94 /*
95 * This is an uniprocessor system
96 * we are in multiprocessor format but uniprocessor system
97 * or in the old uniprocessor format
98 */
99 cpuid_topo->thread_id = -1;
100 cpuid_topo->core_id = 0;
101 cpuid_topo->socket_id = -1;
102 }
103
104 /* update core and thread sibling masks */
105 for_each_possible_cpu(cpu) {
106 struct cputopo_arm *cpu_topo = &cpu_topology[cpu];
107
108 if (cpuid_topo->socket_id == cpu_topo->socket_id) {
109 cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
110 if (cpu != cpuid)
111 cpumask_set_cpu(cpu,
112 &cpuid_topo->core_sibling);
113
114 if (cpuid_topo->core_id == cpu_topo->core_id) {
115 cpumask_set_cpu(cpuid,
116 &cpu_topo->thread_sibling);
117 if (cpu != cpuid)
118 cpumask_set_cpu(cpu,
119 &cpuid_topo->thread_sibling);
120 }
121 }
122 }
123 smp_wmb();
124
125 printk(KERN_INFO "CPU%u: thread %d, cpu %d, socket %d, mpidr %x\n",
126 cpuid, cpu_topology[cpuid].thread_id,
127 cpu_topology[cpuid].core_id,
128 cpu_topology[cpuid].socket_id, mpidr);
129 }
130
131 /*
132 * init_cpu_topology is called at boot when only one cpu is running
133 * which prevent simultaneous write access to cpu_topology array
134 */
init_cpu_topology(void)135 void init_cpu_topology(void)
136 {
137 unsigned int cpu;
138
139 /* init core mask */
140 for_each_possible_cpu(cpu) {
141 struct cputopo_arm *cpu_topo = &(cpu_topology[cpu]);
142
143 cpu_topo->thread_id = -1;
144 cpu_topo->core_id = -1;
145 cpu_topo->socket_id = -1;
146 cpumask_clear(&cpu_topo->core_sibling);
147 cpumask_clear(&cpu_topo->thread_sibling);
148 }
149 smp_wmb();
150 }
151