1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright 2020 Linaro Limited
4 *
5 * Author: Daniel Lezcano <daniel.lezcano@linaro.org>
6 *
7 * The DTPM CPU is based on the energy model. It hooks the CPU in the
8 * DTPM tree which in turns update the power number by propagating the
9 * power number from the CPU energy model information to the parents.
10 *
11 * The association between the power and the performance state, allows
12 * to set the power of the CPU at the OPP granularity.
13 *
14 * The CPU hotplug is supported and the power numbers will be updated
15 * if a CPU is hot plugged / unplugged.
16 */
17#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18
19#include <linux/cpumask.h>
20#include <linux/cpufreq.h>
21#include <linux/cpuhotplug.h>
22#include <linux/dtpm.h>
23#include <linux/energy_model.h>
24#include <linux/of.h>
25#include <linux/pm_qos.h>
26#include <linux/slab.h>
27
28struct dtpm_cpu {
29 struct dtpm dtpm;
30 struct freq_qos_request qos_req;
31 int cpu;
32};
33
34static DEFINE_PER_CPU(struct dtpm_cpu *, dtpm_per_cpu);
35
36static struct dtpm_cpu *to_dtpm_cpu(struct dtpm *dtpm)
37{
38 return container_of(dtpm, struct dtpm_cpu, dtpm);
39}
40
41static u64 set_pd_power_limit(struct dtpm *dtpm, u64 power_limit)
42{
43 struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
44 struct em_perf_domain *pd = em_cpu_get(cpu: dtpm_cpu->cpu);
45 struct em_perf_state *table;
46 struct cpumask cpus;
47 unsigned long freq;
48 u64 power;
49 int i, nr_cpus;
50
51 cpumask_and(dstp: &cpus, cpu_online_mask, to_cpumask(pd->cpus));
52 nr_cpus = cpumask_weight(srcp: &cpus);
53
54 rcu_read_lock();
55 table = em_perf_state_from_pd(pd);
56 for (i = 0; i < pd->nr_perf_states; i++) {
57
58 power = table[i].power * nr_cpus;
59
60 if (power > power_limit)
61 break;
62 }
63
64 freq = table[i - 1].frequency;
65 power_limit = table[i - 1].power * nr_cpus;
66 rcu_read_unlock();
67
68 freq_qos_update_request(req: &dtpm_cpu->qos_req, new_value: freq);
69
70 return power_limit;
71}
72
73static u64 scale_pd_power_uw(struct cpumask *pd_mask, u64 power)
74{
75 unsigned long max, sum_util = 0;
76 int cpu;
77
78 /*
79 * The capacity is the same for all CPUs belonging to
80 * the same perf domain.
81 */
82 max = arch_scale_cpu_capacity(cpu: cpumask_first(srcp: pd_mask));
83
84 for_each_cpu_and(cpu, pd_mask, cpu_online_mask)
85 sum_util += sched_cpu_util(cpu);
86
87 return (power * ((sum_util << 10) / max)) >> 10;
88}
89
90static u64 get_pd_power_uw(struct dtpm *dtpm)
91{
92 struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
93 struct em_perf_state *table;
94 struct em_perf_domain *pd;
95 struct cpumask *pd_mask;
96 unsigned long freq;
97 u64 power = 0;
98 int i;
99
100 pd = em_cpu_get(cpu: dtpm_cpu->cpu);
101
102 pd_mask = em_span_cpus(pd);
103
104 freq = cpufreq_quick_get(cpu: dtpm_cpu->cpu);
105
106 rcu_read_lock();
107 table = em_perf_state_from_pd(pd);
108 for (i = 0; i < pd->nr_perf_states; i++) {
109
110 if (table[i].frequency < freq)
111 continue;
112
113 power = scale_pd_power_uw(pd_mask, power: table[i].power);
114 break;
115 }
116 rcu_read_unlock();
117
118 return power;
119}
120
121static int update_pd_power_uw(struct dtpm *dtpm)
122{
123 struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
124 struct em_perf_domain *em = em_cpu_get(cpu: dtpm_cpu->cpu);
125 struct em_perf_state *table;
126 struct cpumask cpus;
127 int nr_cpus;
128
129 cpumask_and(dstp: &cpus, cpu_online_mask, to_cpumask(em->cpus));
130 nr_cpus = cpumask_weight(srcp: &cpus);
131
132 rcu_read_lock();
133 table = em_perf_state_from_pd(pd: em);
134
135 dtpm->power_min = table[0].power;
136 dtpm->power_min *= nr_cpus;
137
138 dtpm->power_max = table[em->nr_perf_states - 1].power;
139 dtpm->power_max *= nr_cpus;
140
141 rcu_read_unlock();
142
143 return 0;
144}
145
146static void pd_release(struct dtpm *dtpm)
147{
148 struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
149 struct cpufreq_policy *policy;
150
151 if (freq_qos_request_active(req: &dtpm_cpu->qos_req))
152 freq_qos_remove_request(req: &dtpm_cpu->qos_req);
153
154 policy = cpufreq_cpu_get(cpu: dtpm_cpu->cpu);
155 if (policy) {
156 for_each_cpu(dtpm_cpu->cpu, policy->related_cpus)
157 per_cpu(dtpm_per_cpu, dtpm_cpu->cpu) = NULL;
158
159 cpufreq_cpu_put(policy);
160 }
161
162 kfree(objp: dtpm_cpu);
163}
164
165static struct dtpm_ops dtpm_ops = {
166 .set_power_uw = set_pd_power_limit,
167 .get_power_uw = get_pd_power_uw,
168 .update_power_uw = update_pd_power_uw,
169 .release = pd_release,
170};
171
172static int cpuhp_dtpm_cpu_offline(unsigned int cpu)
173{
174 struct dtpm_cpu *dtpm_cpu;
175
176 dtpm_cpu = per_cpu(dtpm_per_cpu, cpu);
177 if (dtpm_cpu)
178 dtpm_update_power(dtpm: &dtpm_cpu->dtpm);
179
180 return 0;
181}
182
183static int cpuhp_dtpm_cpu_online(unsigned int cpu)
184{
185 struct dtpm_cpu *dtpm_cpu;
186
187 dtpm_cpu = per_cpu(dtpm_per_cpu, cpu);
188 if (dtpm_cpu)
189 return dtpm_update_power(dtpm: &dtpm_cpu->dtpm);
190
191 return 0;
192}
193
194static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
195{
196 struct dtpm_cpu *dtpm_cpu;
197 struct cpufreq_policy *policy;
198 struct em_perf_state *table;
199 struct em_perf_domain *pd;
200 char name[CPUFREQ_NAME_LEN];
201 int ret = -ENOMEM;
202
203 dtpm_cpu = per_cpu(dtpm_per_cpu, cpu);
204 if (dtpm_cpu)
205 return 0;
206
207 policy = cpufreq_cpu_get(cpu);
208 if (!policy)
209 return 0;
210
211 pd = em_cpu_get(cpu);
212 if (!pd || em_is_artificial(pd)) {
213 ret = -EINVAL;
214 goto release_policy;
215 }
216
217 dtpm_cpu = kzalloc(size: sizeof(*dtpm_cpu), GFP_KERNEL);
218 if (!dtpm_cpu) {
219 ret = -ENOMEM;
220 goto release_policy;
221 }
222
223 dtpm_init(dtpm: &dtpm_cpu->dtpm, ops: &dtpm_ops);
224 dtpm_cpu->cpu = cpu;
225
226 for_each_cpu(cpu, policy->related_cpus)
227 per_cpu(dtpm_per_cpu, cpu) = dtpm_cpu;
228
229 snprintf(buf: name, size: sizeof(name), fmt: "cpu%d-cpufreq", dtpm_cpu->cpu);
230
231 ret = dtpm_register(name, dtpm: &dtpm_cpu->dtpm, parent);
232 if (ret)
233 goto out_kfree_dtpm_cpu;
234
235 rcu_read_lock();
236 table = em_perf_state_from_pd(pd);
237 ret = freq_qos_add_request(qos: &policy->constraints,
238 req: &dtpm_cpu->qos_req, type: FREQ_QOS_MAX,
239 value: table[pd->nr_perf_states - 1].frequency);
240 rcu_read_unlock();
241 if (ret < 0)
242 goto out_dtpm_unregister;
243
244 cpufreq_cpu_put(policy);
245 return 0;
246
247out_dtpm_unregister:
248 dtpm_unregister(dtpm: &dtpm_cpu->dtpm);
249 dtpm_cpu = NULL;
250
251out_kfree_dtpm_cpu:
252 for_each_cpu(cpu, policy->related_cpus)
253 per_cpu(dtpm_per_cpu, cpu) = NULL;
254 kfree(objp: dtpm_cpu);
255
256release_policy:
257 cpufreq_cpu_put(policy);
258 return ret;
259}
260
261static int dtpm_cpu_setup(struct dtpm *dtpm, struct device_node *np)
262{
263 int cpu;
264
265 cpu = of_cpu_node_to_id(np);
266 if (cpu < 0)
267 return 0;
268
269 return __dtpm_cpu_setup(cpu, parent: dtpm);
270}
271
272static int dtpm_cpu_init(void)
273{
274 int ret;
275
276 /*
277 * The callbacks at CPU hotplug time are calling
278 * dtpm_update_power() which in turns calls update_pd_power().
279 *
280 * The function update_pd_power() uses the online mask to
281 * figure out the power consumption limits.
282 *
283 * At CPUHP_AP_ONLINE_DYN, the CPU is present in the CPU
284 * online mask when the cpuhp_dtpm_cpu_online function is
285 * called, but the CPU is still in the online mask for the
286 * tear down callback. So the power can not be updated when
287 * the CPU is unplugged.
288 *
289 * At CPUHP_AP_DTPM_CPU_DEAD, the situation is the opposite as
290 * above. The CPU online mask is not up to date when the CPU
291 * is plugged in.
292 *
293 * For this reason, we need to call the online and offline
294 * callbacks at different moments when the CPU online mask is
295 * consistent with the power numbers we want to update.
296 */
297 ret = cpuhp_setup_state(state: CPUHP_AP_DTPM_CPU_DEAD, name: "dtpm_cpu:offline",
298 NULL, teardown: cpuhp_dtpm_cpu_offline);
299 if (ret < 0)
300 return ret;
301
302 ret = cpuhp_setup_state(state: CPUHP_AP_ONLINE_DYN, name: "dtpm_cpu:online",
303 startup: cpuhp_dtpm_cpu_online, NULL);
304 if (ret < 0)
305 return ret;
306
307 return 0;
308}
309
310static void dtpm_cpu_exit(void)
311{
312 cpuhp_remove_state_nocalls(state: CPUHP_AP_ONLINE_DYN);
313 cpuhp_remove_state_nocalls(state: CPUHP_AP_DTPM_CPU_DEAD);
314}
315
316struct dtpm_subsys_ops dtpm_cpu_ops = {
317 .name = KBUILD_MODNAME,
318 .init = dtpm_cpu_init,
319 .exit = dtpm_cpu_exit,
320 .setup = dtpm_cpu_setup,
321};
322

source code of linux/drivers/powercap/dtpm_cpu.c