drivers/powercap/dtpm_cpu.c

   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
  28 struct dtpm_cpu {
  29         struct dtpm dtpm;
  30         struct freq_qos_request qos_req;
  31         int cpu;
  32 };
  33
  34 static DEFINE_PER_CPU(struct dtpm_cpu *, dtpm_per_cpu);
  35
  36 static struct dtpm_cpu *to_dtpm_cpu(struct dtpm *dtpm)
  37 {
  38         return container_of(dtpm, struct dtpm_cpu, dtpm);
  39 }
  40
  41 static 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(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(&cpus, cpu_online_mask, to_cpumask(pd->cpus));
  52         nr_cpus = cpumask_weight(&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(&dtpm_cpu->qos_req, freq);
  69
  70         return power_limit;
  71 }
  72
  73 static 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(cpumask_first(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
  90 static 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(dtpm_cpu->cpu);
 101
 102         pd_mask = em_span_cpus(pd);
 103
 104         freq = cpufreq_quick_get(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, table[i].power);
 114                 break;
 115         }
 116         rcu_read_unlock();
 117
 118         return power;
 119 }
 120
 121 static 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(dtpm_cpu->cpu);
 125         struct em_perf_state *table;
 126         struct cpumask cpus;
 127         int nr_cpus;
 128
 129         cpumask_and(&cpus, cpu_online_mask, to_cpumask(em->cpus));
 130         nr_cpus = cpumask_weight(&cpus);
 131
 132         rcu_read_lock();
 133         table = em_perf_state_from_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
 146 static 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(&dtpm_cpu->qos_req))
 152                 freq_qos_remove_request(&dtpm_cpu->qos_req);
 153
 154         policy = cpufreq_cpu_get(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(dtpm_cpu);
 163 }
 164
 165 static 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
 172 static 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_cpu->dtpm);
 179
 180         return 0;
 181 }
 182
 183 static 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_cpu->dtpm);
 190
 191         return 0;
 192 }
 193
 194 static 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(sizeof(*dtpm_cpu), GFP_KERNEL);
 218         if (!dtpm_cpu) {
 219                 ret = -ENOMEM;
 220                 goto release_policy;
 221         }
 222
 223         dtpm_init(&dtpm_cpu->dtpm, &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(name, sizeof(name), "cpu%d-cpufreq", dtpm_cpu->cpu);
 230
 231         ret = dtpm_register(name, &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(&policy->constraints,
 238                                    &dtpm_cpu->qos_req, FREQ_QOS_MAX,
 239                                    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
 247 out_dtpm_unregister:
 248         dtpm_unregister(&dtpm_cpu->dtpm);
 249         dtpm_cpu = NULL;
 250
 251 out_kfree_dtpm_cpu:
 252         for_each_cpu(cpu, policy->related_cpus)
 253                 per_cpu(dtpm_per_cpu, cpu) = NULL;
 254         kfree(dtpm_cpu);
 255
 256 release_policy:
 257         cpufreq_cpu_put(policy);
 258         return ret;
 259 }
 260
 261 static 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, dtpm);
 270 }
 271
 272 static 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(CPUHP_AP_DTPM_CPU_DEAD, "dtpm_cpu:offline",
 298                                 NULL, cpuhp_dtpm_cpu_offline);
 299         if (ret < 0)
 300                 return ret;
 301
 302         ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "dtpm_cpu:online",
 303                                 cpuhp_dtpm_cpu_online, NULL);
 304         if (ret < 0)
 305                 return ret;
 306
 307         return 0;
 308 }
 309
 310 static void dtpm_cpu_exit(void)
 311 {
 312         cpuhp_remove_state_nocalls(CPUHP_AP_ONLINE_DYN);
 313         cpuhp_remove_state_nocalls(CPUHP_AP_DTPM_CPU_DEAD);
 314 }
 315
 316 struct 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 };