2 * arch/arm64/kernel/topology.c
4 * Copyright (C) 2011,2013,2014 Linaro Limited.
6 * Based on the arm32 version written by Vincent Guittot in turn based on
7 * arch/sh/kernel/topology.c
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
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>
21 #include <linux/sched.h>
23 #include <asm/cputype.h>
24 #include <asm/topology.h>
26 static int __init get_cpu_for_node(struct device_node *node)
28 struct device_node *cpu_node;
31 cpu_node = of_parse_phandle(node, "cpu", 0);
35 for_each_possible_cpu(cpu) {
36 if (of_get_cpu_node(cpu, NULL) == cpu_node) {
37 of_node_put(cpu_node);
42 pr_crit("Unable to find CPU node for %s\n", cpu_node->full_name);
44 of_node_put(cpu_node);
48 static int __init parse_core(struct device_node *core, int cluster_id,
55 struct device_node *t;
58 snprintf(name, sizeof(name), "thread%d", i);
59 t = of_get_child_by_name(core, name);
62 cpu = get_cpu_for_node(t);
64 cpu_topology[cpu].cluster_id = cluster_id;
65 cpu_topology[cpu].core_id = core_id;
66 cpu_topology[cpu].thread_id = i;
68 pr_err("%s: Can't get CPU for thread\n",
78 cpu = get_cpu_for_node(core);
81 pr_err("%s: Core has both threads and CPU\n",
86 cpu_topology[cpu].cluster_id = cluster_id;
87 cpu_topology[cpu].core_id = core_id;
89 pr_err("%s: Can't get CPU for leaf core\n", core->full_name);
96 static int __init parse_cluster(struct device_node *cluster, int depth)
100 bool has_cores = false;
101 struct device_node *c;
102 static int cluster_id __initdata;
107 * First check for child clusters; we currently ignore any
108 * information about the nesting of clusters and present the
109 * scheduler with a flat list of them.
113 snprintf(name, sizeof(name), "cluster%d", i);
114 c = of_get_child_by_name(cluster, name);
117 ret = parse_cluster(c, depth + 1);
125 /* Now check for cores */
128 snprintf(name, sizeof(name), "core%d", i);
129 c = of_get_child_by_name(cluster, name);
134 pr_err("%s: cpu-map children should be clusters\n",
141 ret = parse_core(c, cluster_id, core_id++);
143 pr_err("%s: Non-leaf cluster with core %s\n",
144 cluster->full_name, name);
155 if (leaf && !has_cores)
156 pr_warn("%s: empty cluster\n", cluster->full_name);
164 static int __init parse_dt_topology(void)
166 struct device_node *cn, *map;
170 cn = of_find_node_by_path("/cpus");
172 pr_err("No CPU information found in DT\n");
177 * When topology is provided cpu-map is essentially a root
178 * cluster with restricted subnodes.
180 map = of_get_child_by_name(cn, "cpu-map");
184 ret = parse_cluster(map, 0);
189 * Check that all cores are in the topology; the SMP code will
190 * only mark cores described in the DT as possible.
192 for_each_possible_cpu(cpu)
193 if (cpu_topology[cpu].cluster_id == -1)
206 struct cpu_topology cpu_topology[NR_CPUS];
207 EXPORT_SYMBOL_GPL(cpu_topology);
209 const struct cpumask *cpu_coregroup_mask(int cpu)
211 return &cpu_topology[cpu].core_sibling;
214 static void update_siblings_masks(unsigned int cpuid)
216 struct cpu_topology *cpu_topo, *cpuid_topo = &cpu_topology[cpuid];
219 /* update core and thread sibling masks */
220 for_each_possible_cpu(cpu) {
221 cpu_topo = &cpu_topology[cpu];
223 if (cpuid_topo->cluster_id != cpu_topo->cluster_id)
226 cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
228 cpumask_set_cpu(cpu, &cpuid_topo->core_sibling);
230 if (cpuid_topo->core_id != cpu_topo->core_id)
233 cpumask_set_cpu(cpuid, &cpu_topo->thread_sibling);
235 cpumask_set_cpu(cpu, &cpuid_topo->thread_sibling);
239 void store_cpu_topology(unsigned int cpuid)
241 struct cpu_topology *cpuid_topo = &cpu_topology[cpuid];
244 if (cpuid_topo->cluster_id != -1)
245 goto topology_populated;
247 mpidr = read_cpuid_mpidr();
249 /* Uniprocessor systems can rely on default topology values */
250 if (mpidr & MPIDR_UP_BITMASK)
253 /* Create cpu topology mapping based on MPIDR. */
254 if (mpidr & MPIDR_MT_BITMASK) {
255 /* Multiprocessor system : Multi-threads per core */
256 cpuid_topo->thread_id = MPIDR_AFFINITY_LEVEL(mpidr, 0);
257 cpuid_topo->core_id = MPIDR_AFFINITY_LEVEL(mpidr, 1);
258 cpuid_topo->cluster_id = MPIDR_AFFINITY_LEVEL(mpidr, 2) |
259 MPIDR_AFFINITY_LEVEL(mpidr, 3) << 8;
261 /* Multiprocessor system : Single-thread per core */
262 cpuid_topo->thread_id = -1;
263 cpuid_topo->core_id = MPIDR_AFFINITY_LEVEL(mpidr, 0);
264 cpuid_topo->cluster_id = MPIDR_AFFINITY_LEVEL(mpidr, 1) |
265 MPIDR_AFFINITY_LEVEL(mpidr, 2) << 8 |
266 MPIDR_AFFINITY_LEVEL(mpidr, 3) << 16;
269 pr_debug("CPU%u: cluster %d core %d thread %d mpidr %#016llx\n",
270 cpuid, cpuid_topo->cluster_id, cpuid_topo->core_id,
271 cpuid_topo->thread_id, mpidr);
274 update_siblings_masks(cpuid);
277 static void __init reset_cpu_topology(void)
281 for_each_possible_cpu(cpu) {
282 struct cpu_topology *cpu_topo = &cpu_topology[cpu];
284 cpu_topo->thread_id = -1;
285 cpu_topo->core_id = 0;
286 cpu_topo->cluster_id = -1;
288 cpumask_clear(&cpu_topo->core_sibling);
289 cpumask_set_cpu(cpu, &cpu_topo->core_sibling);
290 cpumask_clear(&cpu_topo->thread_sibling);
291 cpumask_set_cpu(cpu, &cpu_topo->thread_sibling);
295 void __init init_cpu_topology(void)
297 reset_cpu_topology();
300 * Discard anything that was parsed if we hit an error so we
301 * don't use partial information.
303 if (of_have_populated_dt() && parse_dt_topology())
304 reset_cpu_topology();