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 #include <linux/units.h>
  28
  29 struct dtpm_cpu {
  30         struct dtpm dtpm;
  31         struct freq_qos_request qos_req;
  32         int cpu;
  33 };
  34
  35 static DEFINE_PER_CPU(struct dtpm_cpu *, dtpm_per_cpu);
  36
  37 static struct dtpm_cpu *to_dtpm_cpu(struct dtpm *dtpm)
  38 {
  39         return container_of(dtpm, struct dtpm_cpu, dtpm);
  40 }
  41
  42 static u64 set_pd_power_limit(struct dtpm *dtpm, u64 power_limit)
  43 {
  44         struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
  45         struct em_perf_domain *pd = em_cpu_get(dtpm_cpu->cpu);
  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         for (i = 0; i < pd->nr_perf_states; i++) {
  55
  56                 power = pd->table[i].power * MICROWATT_PER_MILLIWATT * nr_cpus;
  57
  58                 if (power > power_limit)
  59                         break;
  60         }
  61
  62         freq = pd->table[i - 1].frequency;
  63
  64         freq_qos_update_request(&dtpm_cpu->qos_req, freq);
  65
  66         power_limit = pd->table[i - 1].power *
  67                 MICROWATT_PER_MILLIWATT * nr_cpus;
  68
  69         return power_limit;
  70 }
  71
  72 static u64 scale_pd_power_uw(struct cpumask *pd_mask, u64 power)
  73 {
  74         unsigned long max, sum_util = 0;
  75         int cpu;
  76
  77         /*
  78          * The capacity is the same for all CPUs belonging to
  79          * the same perf domain.
  80          */
  81         max = arch_scale_cpu_capacity(cpumask_first(pd_mask));
  82
  83         for_each_cpu_and(cpu, pd_mask, cpu_online_mask)
  84                 sum_util += sched_cpu_util(cpu);
  85
  86         return (power * ((sum_util << 10) / max)) >> 10;
  87 }
  88
  89 static u64 get_pd_power_uw(struct dtpm *dtpm)
  90 {
  91         struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
  92         struct em_perf_domain *pd;
  93         struct cpumask *pd_mask;
  94         unsigned long freq;
  95         int i;
  96
  97         pd = em_cpu_get(dtpm_cpu->cpu);
  98
  99         pd_mask = em_span_cpus(pd);
 100
 101         freq = cpufreq_quick_get(dtpm_cpu->cpu);
 102
 103         for (i = 0; i < pd->nr_perf_states; i++) {
 104
 105                 if (pd->table[i].frequency < freq)
 106                         continue;
 107
 108                 return scale_pd_power_uw(pd_mask, pd->table[i].power *
 109                                          MICROWATT_PER_MILLIWATT);
 110         }
 111
 112         return 0;
 113 }
 114
 115 static int update_pd_power_uw(struct dtpm *dtpm)
 116 {
 117         struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
 118         struct em_perf_domain *em = em_cpu_get(dtpm_cpu->cpu);
 119         struct cpumask cpus;
 120         int nr_cpus;
 121
 122         cpumask_and(&cpus, cpu_online_mask, to_cpumask(em->cpus));
 123         nr_cpus = cpumask_weight(&cpus);
 124
 125         dtpm->power_min = em->table[0].power;
 126         dtpm->power_min *= MICROWATT_PER_MILLIWATT;
 127         dtpm->power_min *= nr_cpus;
 128
 129         dtpm->power_max = em->table[em->nr_perf_states - 1].power;
 130         dtpm->power_max *= MICROWATT_PER_MILLIWATT;
 131         dtpm->power_max *= nr_cpus;
 132
 133         return 0;
 134 }
 135
 136 static void pd_release(struct dtpm *dtpm)
 137 {
 138         struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
 139         struct cpufreq_policy *policy;
 140
 141         if (freq_qos_request_active(&dtpm_cpu->qos_req))
 142                 freq_qos_remove_request(&dtpm_cpu->qos_req);
 143
 144         policy = cpufreq_cpu_get(dtpm_cpu->cpu);
 145         if (policy) {
 146                 for_each_cpu(dtpm_cpu->cpu, policy->related_cpus)
 147                         per_cpu(dtpm_per_cpu, dtpm_cpu->cpu) = NULL;
 148         }
 149
 150         kfree(dtpm_cpu);
 151 }
 152
 153 static struct dtpm_ops dtpm_ops = {
 154         .set_power_uw    = set_pd_power_limit,
 155         .get_power_uw    = get_pd_power_uw,
 156         .update_power_uw = update_pd_power_uw,
 157         .release         = pd_release,
 158 };
 159
 160 static int cpuhp_dtpm_cpu_offline(unsigned int cpu)
 161 {
 162         struct dtpm_cpu *dtpm_cpu;
 163
 164         dtpm_cpu = per_cpu(dtpm_per_cpu, cpu);
 165         if (dtpm_cpu)
 166                 dtpm_update_power(&dtpm_cpu->dtpm);
 167
 168         return 0;
 169 }
 170
 171 static int cpuhp_dtpm_cpu_online(unsigned int cpu)
 172 {
 173         struct dtpm_cpu *dtpm_cpu;
 174
 175         dtpm_cpu = per_cpu(dtpm_per_cpu, cpu);
 176         if (dtpm_cpu)
 177                 return dtpm_update_power(&dtpm_cpu->dtpm);
 178
 179         return 0;
 180 }
 181
 182 static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
 183 {
 184         struct dtpm_cpu *dtpm_cpu;
 185         struct cpufreq_policy *policy;
 186         struct em_perf_domain *pd;
 187         char name[CPUFREQ_NAME_LEN];
 188         int ret = -ENOMEM;
 189
 190         dtpm_cpu = per_cpu(dtpm_per_cpu, cpu);
 191         if (dtpm_cpu)
 192                 return 0;
 193
 194         policy = cpufreq_cpu_get(cpu);
 195         if (!policy)
 196                 return 0;
 197
 198         pd = em_cpu_get(cpu);
 199         if (!pd || em_is_artificial(pd))
 200                 return -EINVAL;
 201
 202         dtpm_cpu = kzalloc(sizeof(*dtpm_cpu), GFP_KERNEL);
 203         if (!dtpm_cpu)
 204                 return -ENOMEM;
 205
 206         dtpm_init(&dtpm_cpu->dtpm, &dtpm_ops);
 207         dtpm_cpu->cpu = cpu;
 208
 209         for_each_cpu(cpu, policy->related_cpus)
 210                 per_cpu(dtpm_per_cpu, cpu) = dtpm_cpu;
 211
 212         snprintf(name, sizeof(name), "cpu%d-cpufreq", dtpm_cpu->cpu);
 213
 214         ret = dtpm_register(name, &dtpm_cpu->dtpm, parent);
 215         if (ret)
 216                 goto out_kfree_dtpm_cpu;
 217
 218         ret = freq_qos_add_request(&policy->constraints,
 219                                    &dtpm_cpu->qos_req, FREQ_QOS_MAX,
 220                                    pd->table[pd->nr_perf_states - 1].frequency);
 221         if (ret)
 222                 goto out_dtpm_unregister;
 223
 224         return 0;
 225
 226 out_dtpm_unregister:
 227         dtpm_unregister(&dtpm_cpu->dtpm);
 228         dtpm_cpu = NULL;
 229
 230 out_kfree_dtpm_cpu:
 231         for_each_cpu(cpu, policy->related_cpus)
 232                 per_cpu(dtpm_per_cpu, cpu) = NULL;
 233         kfree(dtpm_cpu);
 234
 235         return ret;
 236 }
 237
 238 static int dtpm_cpu_setup(struct dtpm *dtpm, struct device_node *np)
 239 {
 240         int cpu;
 241
 242         cpu = of_cpu_node_to_id(np);
 243         if (cpu < 0)
 244                 return 0;
 245
 246         return __dtpm_cpu_setup(cpu, dtpm);
 247 }
 248
 249 static int dtpm_cpu_init(void)
 250 {
 251         int ret;
 252
 253         /*
 254          * The callbacks at CPU hotplug time are calling
 255          * dtpm_update_power() which in turns calls update_pd_power().
 256          *
 257          * The function update_pd_power() uses the online mask to
 258          * figure out the power consumption limits.
 259          *
 260          * At CPUHP_AP_ONLINE_DYN, the CPU is present in the CPU
 261          * online mask when the cpuhp_dtpm_cpu_online function is
 262          * called, but the CPU is still in the online mask for the
 263          * tear down callback. So the power can not be updated when
 264          * the CPU is unplugged.
 265          *
 266          * At CPUHP_AP_DTPM_CPU_DEAD, the situation is the opposite as
 267          * above. The CPU online mask is not up to date when the CPU
 268          * is plugged in.
 269          *
 270          * For this reason, we need to call the online and offline
 271          * callbacks at different moments when the CPU online mask is
 272          * consistent with the power numbers we want to update.
 273          */
 274         ret = cpuhp_setup_state(CPUHP_AP_DTPM_CPU_DEAD, "dtpm_cpu:offline",
 275                                 NULL, cpuhp_dtpm_cpu_offline);
 276         if (ret < 0)
 277                 return ret;
 278
 279         ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "dtpm_cpu:online",
 280                                 cpuhp_dtpm_cpu_online, NULL);
 281         if (ret < 0)
 282                 return ret;
 283
 284         return 0;
 285 }
 286
 287 static void dtpm_cpu_exit(void)
 288 {
 289         cpuhp_remove_state_nocalls(CPUHP_AP_ONLINE_DYN);
 290         cpuhp_remove_state_nocalls(CPUHP_AP_DTPM_CPU_DEAD);
 291 }
 292
 293 struct dtpm_subsys_ops dtpm_cpu_ops = {
 294         .name = KBUILD_MODNAME,
 295         .init = dtpm_cpu_init,
 296         .exit = dtpm_cpu_exit,
 297         .setup = dtpm_cpu_setup,
 298 };