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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/arch_topology.h>
15#include <linux/cpu.h>
16#include <linux/cpufreq.h>
17#include <linux/cpumask.h>
18#include <linux/export.h>
19#include <linux/init.h>
20#include <linux/percpu.h>
21#include <linux/node.h>
22#include <linux/nodemask.h>
23#include <linux/of.h>
24#include <linux/sched.h>
25#include <linux/sched/topology.h>
26#include <linux/slab.h>
27#include <linux/string.h>
28
29#include <asm/cpu.h>
30#include <asm/cputype.h>
31#include <asm/topology.h>
32
33/*
34 * cpu capacity scale management
35 */
36
37/*
38 * cpu capacity table
39 * This per cpu data structure describes the relative capacity of each core.
40 * On a heteregenous system, cores don't have the same computation capacity
41 * and we reflect that difference in the cpu_capacity field so the scheduler
42 * can take this difference into account during load balance. A per cpu
43 * structure is preferred because each CPU updates its own cpu_capacity field
44 * during the load balance except for idle cores. One idle core is selected
45 * to run the rebalance_domains for all idle cores and the cpu_capacity can be
46 * updated during this sequence.
47 */
48
49#ifdef CONFIG_OF
50struct cpu_efficiency {
51 const char *compatible;
52 unsigned long efficiency;
53};
54
55/*
56 * Table of relative efficiency of each processors
57 * The efficiency value must fit in 20bit and the final
58 * cpu_scale value must be in the range
59 * 0 < cpu_scale < 3*SCHED_CAPACITY_SCALE/2
60 * in order to return at most 1 when DIV_ROUND_CLOSEST
61 * is used to compute the capacity of a CPU.
62 * Processors that are not defined in the table,
63 * use the default SCHED_CAPACITY_SCALE value for cpu_scale.
64 */
65static const struct cpu_efficiency table_efficiency[] = {
66 {"arm,cortex-a15", 3891},
67 {"arm,cortex-a7", 2048},
68 {NULL, },
69};
70
71static unsigned long *__cpu_capacity;
72#define cpu_capacity(cpu) __cpu_capacity[cpu]
73
74static unsigned long middle_capacity = 1;
75static bool cap_from_dt = true;
76
77/*
78 * Iterate all CPUs' descriptor in DT and compute the efficiency
79 * (as per table_efficiency). Also calculate a middle efficiency
80 * as close as possible to (max{eff_i} - min{eff_i}) / 2
81 * This is later used to scale the cpu_capacity field such that an
82 * 'average' CPU is of middle capacity. Also see the comments near
83 * table_efficiency[] and update_cpu_capacity().
84 */
85static void __init parse_dt_topology(void)
86{
87 const struct cpu_efficiency *cpu_eff;
88 struct device_node *cn = NULL;
89 unsigned long min_capacity = ULONG_MAX;
90 unsigned long max_capacity = 0;
91 unsigned long capacity = 0;
92 int cpu = 0;
93
94 __cpu_capacity = kcalloc(nr_cpu_ids, sizeof(*__cpu_capacity),
95 GFP_NOWAIT);
96
97 for_each_possible_cpu(cpu) {
98 const __be32 *rate;
99 int len;
100
101 /* too early to use cpu->of_node */
102 cn = of_get_cpu_node(cpu, NULL);
103 if (!cn) {
104 pr_err("missing device node for CPU %d\n", cpu);
105 continue;
106 }
107
108 if (topology_parse_cpu_capacity(cn, cpu)) {
109 of_node_put(cn);
110 continue;
111 }
112
113 cap_from_dt = false;
114
115 for (cpu_eff = table_efficiency; cpu_eff->compatible; cpu_eff++)
116 if (of_device_is_compatible(cn, cpu_eff->compatible))
117 break;
118
119 if (cpu_eff->compatible == NULL)
120 continue;
121
122 rate = of_get_property(cn, "clock-frequency", &len);
123 if (!rate || len != 4) {
124 pr_err("%pOF missing clock-frequency property\n", cn);
125 continue;
126 }
127
128 capacity = ((be32_to_cpup(rate)) >> 20) * cpu_eff->efficiency;
129
130 /* Save min capacity of the system */
131 if (capacity < min_capacity)
132 min_capacity = capacity;
133
134 /* Save max capacity of the system */
135 if (capacity > max_capacity)
136 max_capacity = capacity;
137
138 cpu_capacity(cpu) = capacity;
139 }
140
141 /* If min and max capacities are equals, we bypass the update of the
142 * cpu_scale because all CPUs have the same capacity. Otherwise, we
143 * compute a middle_capacity factor that will ensure that the capacity
144 * of an 'average' CPU of the system will be as close as possible to
145 * SCHED_CAPACITY_SCALE, which is the default value, but with the
146 * constraint explained near table_efficiency[].
147 */
148 if (4*max_capacity < (3*(max_capacity + min_capacity)))
149 middle_capacity = (min_capacity + max_capacity)
150 >> (SCHED_CAPACITY_SHIFT+1);
151 else
152 middle_capacity = ((max_capacity / 3)
153 >> (SCHED_CAPACITY_SHIFT-1)) + 1;
154
155 if (cap_from_dt)
156 topology_normalize_cpu_scale();
157}
158
159/*
160 * Look for a customed capacity of a CPU in the cpu_capacity table during the
161 * boot. The update of all CPUs is in O(n^2) for heteregeneous system but the
162 * function returns directly for SMP system.
163 */
164static void update_cpu_capacity(unsigned int cpu)
165{
166 if (!cpu_capacity(cpu) || cap_from_dt)
167 return;
168
169 topology_set_cpu_scale(cpu, cpu_capacity(cpu) / middle_capacity);
170
171 pr_info("CPU%u: update cpu_capacity %lu\n",
172 cpu, topology_get_cpu_scale(cpu));
173}
174
175#else
176static inline void parse_dt_topology(void) {}
177static inline void update_cpu_capacity(unsigned int cpuid) {}
178#endif
179
180/*
181 * The current assumption is that we can power gate each core independently.
182 * This will be superseded by DT binding once available.
183 */
184const struct cpumask *cpu_corepower_mask(int cpu)
185{
186 return &cpu_topology[cpu].thread_sibling;
187}
188
189/*
190 * store_cpu_topology is called at boot when only one cpu is running
191 * and with the mutex cpu_hotplug.lock locked, when several cpus have booted,
192 * which prevents simultaneous write access to cpu_topology array
193 */
194void store_cpu_topology(unsigned int cpuid)
195{
196 struct cpu_topology *cpuid_topo = &cpu_topology[cpuid];
197 unsigned int mpidr;
198
199 if (cpuid_topo->package_id != -1)
200 goto topology_populated;
201
202 mpidr = read_cpuid_mpidr();
203
204 /* create cpu topology mapping */
205 if ((mpidr & MPIDR_SMP_BITMASK) == MPIDR_SMP_VALUE) {
206 /*
207 * This is a multiprocessor system
208 * multiprocessor format & multiprocessor mode field are set
209 */
210
211 if (mpidr & MPIDR_MT_BITMASK) {
212 /* core performance interdependency */
213 cpuid_topo->thread_id = MPIDR_AFFINITY_LEVEL(mpidr, 0);
214 cpuid_topo->core_id = MPIDR_AFFINITY_LEVEL(mpidr, 1);
215 cpuid_topo->package_id = MPIDR_AFFINITY_LEVEL(mpidr, 2);
216 } else {
217 /* largely independent cores */
218 cpuid_topo->thread_id = -1;
219 cpuid_topo->core_id = MPIDR_AFFINITY_LEVEL(mpidr, 0);
220 cpuid_topo->package_id = MPIDR_AFFINITY_LEVEL(mpidr, 1);
221 }
222 } else {
223 /*
224 * This is an uniprocessor system
225 * we are in multiprocessor format but uniprocessor system
226 * or in the old uniprocessor format
227 */
228 cpuid_topo->thread_id = -1;
229 cpuid_topo->core_id = 0;
230 cpuid_topo->package_id = -1;
231 }
232
233 update_cpu_capacity(cpuid);
234
235 pr_info("CPU%u: thread %d, cpu %d, socket %d, mpidr %x\n",
236 cpuid, cpu_topology[cpuid].thread_id,
237 cpu_topology[cpuid].core_id,
238 cpu_topology[cpuid].package_id, mpidr);
239
240topology_populated:
241 update_siblings_masks(cpuid);
242}
243
244static inline int cpu_corepower_flags(void)
245{
246 return SD_SHARE_PKG_RESOURCES | SD_SHARE_POWERDOMAIN;
247}
248
249static struct sched_domain_topology_level arm_topology[] = {
250#ifdef CONFIG_SCHED_MC
251 { cpu_corepower_mask, cpu_corepower_flags, SD_INIT_NAME(GMC) },
252 { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
253#endif
254 { cpu_cpu_mask, SD_INIT_NAME(DIE) },
255 { NULL, },
256};
257
258/*
259 * init_cpu_topology is called at boot when only one cpu is running
260 * which prevent simultaneous write access to cpu_topology array
261 */
262void __init init_cpu_topology(void)
263{
264 reset_cpu_topology();
265 smp_wmb();
266
267 parse_dt_topology();
268
269 /* Set scheduler topology descriptor */
270 set_sched_topology(arm_topology);
271}
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/arch_topology.h>
15#include <linux/cpu.h>
16#include <linux/cpufreq.h>
17#include <linux/cpumask.h>
18#include <linux/export.h>
19#include <linux/init.h>
20#include <linux/percpu.h>
21#include <linux/node.h>
22#include <linux/nodemask.h>
23#include <linux/of.h>
24#include <linux/sched.h>
25#include <linux/sched/topology.h>
26#include <linux/slab.h>
27#include <linux/string.h>
28
29#include <asm/cpu.h>
30#include <asm/cputype.h>
31#include <asm/topology.h>
32
33/*
34 * cpu capacity scale management
35 */
36
37/*
38 * cpu capacity table
39 * This per cpu data structure describes the relative capacity of each core.
40 * On a heteregenous system, cores don't have the same computation capacity
41 * and we reflect that difference in the cpu_capacity field so the scheduler
42 * can take this difference into account during load balance. A per cpu
43 * structure is preferred because each CPU updates its own cpu_capacity field
44 * during the load balance except for idle cores. One idle core is selected
45 * to run the rebalance_domains for all idle cores and the cpu_capacity can be
46 * updated during this sequence.
47 */
48
49#ifdef CONFIG_OF
50struct cpu_efficiency {
51 const char *compatible;
52 unsigned long efficiency;
53};
54
55/*
56 * Table of relative efficiency of each processors
57 * The efficiency value must fit in 20bit and the final
58 * cpu_scale value must be in the range
59 * 0 < cpu_scale < 3*SCHED_CAPACITY_SCALE/2
60 * in order to return at most 1 when DIV_ROUND_CLOSEST
61 * is used to compute the capacity of a CPU.
62 * Processors that are not defined in the table,
63 * use the default SCHED_CAPACITY_SCALE value for cpu_scale.
64 */
65static const struct cpu_efficiency table_efficiency[] = {
66 {"arm,cortex-a15", 3891},
67 {"arm,cortex-a7", 2048},
68 {NULL, },
69};
70
71static unsigned long *__cpu_capacity;
72#define cpu_capacity(cpu) __cpu_capacity[cpu]
73
74static unsigned long middle_capacity = 1;
75static bool cap_from_dt = true;
76
77/*
78 * Iterate all CPUs' descriptor in DT and compute the efficiency
79 * (as per table_efficiency). Also calculate a middle efficiency
80 * as close as possible to (max{eff_i} - min{eff_i}) / 2
81 * This is later used to scale the cpu_capacity field such that an
82 * 'average' CPU is of middle capacity. Also see the comments near
83 * table_efficiency[] and update_cpu_capacity().
84 */
85static void __init parse_dt_topology(void)
86{
87 const struct cpu_efficiency *cpu_eff;
88 struct device_node *cn = NULL;
89 unsigned long min_capacity = ULONG_MAX;
90 unsigned long max_capacity = 0;
91 unsigned long capacity = 0;
92 int cpu = 0;
93
94 __cpu_capacity = kcalloc(nr_cpu_ids, sizeof(*__cpu_capacity),
95 GFP_NOWAIT);
96
97 cn = of_find_node_by_path("/cpus");
98 if (!cn) {
99 pr_err("No CPU information found in DT\n");
100 return;
101 }
102
103 for_each_possible_cpu(cpu) {
104 const u32 *rate;
105 int len;
106
107 /* too early to use cpu->of_node */
108 cn = of_get_cpu_node(cpu, NULL);
109 if (!cn) {
110 pr_err("missing device node for CPU %d\n", cpu);
111 continue;
112 }
113
114 if (topology_parse_cpu_capacity(cn, cpu)) {
115 of_node_put(cn);
116 continue;
117 }
118
119 cap_from_dt = false;
120
121 for (cpu_eff = table_efficiency; cpu_eff->compatible; cpu_eff++)
122 if (of_device_is_compatible(cn, cpu_eff->compatible))
123 break;
124
125 if (cpu_eff->compatible == NULL)
126 continue;
127
128 rate = of_get_property(cn, "clock-frequency", &len);
129 if (!rate || len != 4) {
130 pr_err("%pOF missing clock-frequency property\n", cn);
131 continue;
132 }
133
134 capacity = ((be32_to_cpup(rate)) >> 20) * cpu_eff->efficiency;
135
136 /* Save min capacity of the system */
137 if (capacity < min_capacity)
138 min_capacity = capacity;
139
140 /* Save max capacity of the system */
141 if (capacity > max_capacity)
142 max_capacity = capacity;
143
144 cpu_capacity(cpu) = capacity;
145 }
146
147 /* If min and max capacities are equals, we bypass the update of the
148 * cpu_scale because all CPUs have the same capacity. Otherwise, we
149 * compute a middle_capacity factor that will ensure that the capacity
150 * of an 'average' CPU of the system will be as close as possible to
151 * SCHED_CAPACITY_SCALE, which is the default value, but with the
152 * constraint explained near table_efficiency[].
153 */
154 if (4*max_capacity < (3*(max_capacity + min_capacity)))
155 middle_capacity = (min_capacity + max_capacity)
156 >> (SCHED_CAPACITY_SHIFT+1);
157 else
158 middle_capacity = ((max_capacity / 3)
159 >> (SCHED_CAPACITY_SHIFT-1)) + 1;
160
161 if (cap_from_dt)
162 topology_normalize_cpu_scale();
163}
164
165/*
166 * Look for a customed capacity of a CPU in the cpu_capacity table during the
167 * boot. The update of all CPUs is in O(n^2) for heteregeneous system but the
168 * function returns directly for SMP system.
169 */
170static void update_cpu_capacity(unsigned int cpu)
171{
172 if (!cpu_capacity(cpu) || cap_from_dt)
173 return;
174
175 topology_set_cpu_scale(cpu, cpu_capacity(cpu) / middle_capacity);
176
177 pr_info("CPU%u: update cpu_capacity %lu\n",
178 cpu, topology_get_cpu_scale(NULL, cpu));
179}
180
181#else
182static inline void parse_dt_topology(void) {}
183static inline void update_cpu_capacity(unsigned int cpuid) {}
184#endif
185
186 /*
187 * cpu topology table
188 */
189struct cputopo_arm cpu_topology[NR_CPUS];
190EXPORT_SYMBOL_GPL(cpu_topology);
191
192const struct cpumask *cpu_coregroup_mask(int cpu)
193{
194 return &cpu_topology[cpu].core_sibling;
195}
196
197/*
198 * The current assumption is that we can power gate each core independently.
199 * This will be superseded by DT binding once available.
200 */
201const struct cpumask *cpu_corepower_mask(int cpu)
202{
203 return &cpu_topology[cpu].thread_sibling;
204}
205
206static void update_siblings_masks(unsigned int cpuid)
207{
208 struct cputopo_arm *cpu_topo, *cpuid_topo = &cpu_topology[cpuid];
209 int cpu;
210
211 /* update core and thread sibling masks */
212 for_each_possible_cpu(cpu) {
213 cpu_topo = &cpu_topology[cpu];
214
215 if (cpuid_topo->socket_id != cpu_topo->socket_id)
216 continue;
217
218 cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
219 if (cpu != cpuid)
220 cpumask_set_cpu(cpu, &cpuid_topo->core_sibling);
221
222 if (cpuid_topo->core_id != cpu_topo->core_id)
223 continue;
224
225 cpumask_set_cpu(cpuid, &cpu_topo->thread_sibling);
226 if (cpu != cpuid)
227 cpumask_set_cpu(cpu, &cpuid_topo->thread_sibling);
228 }
229 smp_wmb();
230}
231
232/*
233 * store_cpu_topology is called at boot when only one cpu is running
234 * and with the mutex cpu_hotplug.lock locked, when several cpus have booted,
235 * which prevents simultaneous write access to cpu_topology array
236 */
237void store_cpu_topology(unsigned int cpuid)
238{
239 struct cputopo_arm *cpuid_topo = &cpu_topology[cpuid];
240 unsigned int mpidr;
241
242 /* If the cpu topology has been already set, just return */
243 if (cpuid_topo->core_id != -1)
244 return;
245
246 mpidr = read_cpuid_mpidr();
247
248 /* create cpu topology mapping */
249 if ((mpidr & MPIDR_SMP_BITMASK) == MPIDR_SMP_VALUE) {
250 /*
251 * This is a multiprocessor system
252 * multiprocessor format & multiprocessor mode field are set
253 */
254
255 if (mpidr & MPIDR_MT_BITMASK) {
256 /* core performance interdependency */
257 cpuid_topo->thread_id = MPIDR_AFFINITY_LEVEL(mpidr, 0);
258 cpuid_topo->core_id = MPIDR_AFFINITY_LEVEL(mpidr, 1);
259 cpuid_topo->socket_id = MPIDR_AFFINITY_LEVEL(mpidr, 2);
260 } else {
261 /* largely independent cores */
262 cpuid_topo->thread_id = -1;
263 cpuid_topo->core_id = MPIDR_AFFINITY_LEVEL(mpidr, 0);
264 cpuid_topo->socket_id = MPIDR_AFFINITY_LEVEL(mpidr, 1);
265 }
266 } else {
267 /*
268 * This is an uniprocessor system
269 * we are in multiprocessor format but uniprocessor system
270 * or in the old uniprocessor format
271 */
272 cpuid_topo->thread_id = -1;
273 cpuid_topo->core_id = 0;
274 cpuid_topo->socket_id = -1;
275 }
276
277 update_siblings_masks(cpuid);
278
279 update_cpu_capacity(cpuid);
280
281 pr_info("CPU%u: thread %d, cpu %d, socket %d, mpidr %x\n",
282 cpuid, cpu_topology[cpuid].thread_id,
283 cpu_topology[cpuid].core_id,
284 cpu_topology[cpuid].socket_id, mpidr);
285}
286
287static inline int cpu_corepower_flags(void)
288{
289 return SD_SHARE_PKG_RESOURCES | SD_SHARE_POWERDOMAIN;
290}
291
292static struct sched_domain_topology_level arm_topology[] = {
293#ifdef CONFIG_SCHED_MC
294 { cpu_corepower_mask, cpu_corepower_flags, SD_INIT_NAME(GMC) },
295 { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
296#endif
297 { cpu_cpu_mask, SD_INIT_NAME(DIE) },
298 { NULL, },
299};
300
301/*
302 * init_cpu_topology is called at boot when only one cpu is running
303 * which prevent simultaneous write access to cpu_topology array
304 */
305void __init init_cpu_topology(void)
306{
307 unsigned int cpu;
308
309 /* init core mask and capacity */
310 for_each_possible_cpu(cpu) {
311 struct cputopo_arm *cpu_topo = &(cpu_topology[cpu]);
312
313 cpu_topo->thread_id = -1;
314 cpu_topo->core_id = -1;
315 cpu_topo->socket_id = -1;
316 cpumask_clear(&cpu_topo->core_sibling);
317 cpumask_clear(&cpu_topo->thread_sibling);
318 }
319 smp_wmb();
320
321 parse_dt_topology();
322
323 /* Set scheduler topology descriptor */
324 set_sched_topology(arm_topology);
325}