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         unsigned long freq;
  47         u64 power;
  48         int i, nr_cpus;
  49
  50         nr_cpus = cpumask_weight_and(cpu_online_mask, to_cpumask(pd->cpus));
  51
  52         rcu_read_lock();
  53         table = em_perf_state_from_pd(pd);
  54         for (i = 0; i < pd->nr_perf_states; i++) {
  55
  56                 power = table[i].power * nr_cpus;
  57
  58                 if (power > power_limit)
  59                         break;
  60         }
  61
  62         freq = table[i - 1].frequency;
  63         power_limit = table[i - 1].power * nr_cpus;
  64         rcu_read_unlock();
  65
  66         freq_qos_update_request(&dtpm_cpu->qos_req, freq);
  67
  68         return power_limit;
  69 }
  70
  71 static u64 scale_pd_power_uw(struct cpumask *pd_mask, u64 power)
  72 {
  73         unsigned long max, sum_util = 0;
  74         int cpu;
  75
  76         /*
  77          * The capacity is the same for all CPUs belonging to
  78          * the same perf domain.
  79          */
  80         max = arch_scale_cpu_capacity(cpumask_first(pd_mask));
  81
  82         for_each_cpu_and(cpu, pd_mask, cpu_online_mask)
  83                 sum_util += sched_cpu_util(cpu);
  84
  85         return (power * ((sum_util << 10) / max)) >> 10;
  86 }
  87
  88 static u64 get_pd_power_uw(struct dtpm *dtpm)
  89 {
  90         struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
  91         struct em_perf_state *table;
  92         struct em_perf_domain *pd;
  93         struct cpumask *pd_mask;
  94         unsigned long freq;
  95         u64 power = 0;
  96         int i;
  97
  98         pd = em_cpu_get(dtpm_cpu->cpu);
  99
 100         pd_mask = em_span_cpus(pd);
 101
 102         freq = cpufreq_quick_get(dtpm_cpu->cpu);
 103
 104         rcu_read_lock();
 105         table = em_perf_state_from_pd(pd);
 106         for (i = 0; i < pd->nr_perf_states; i++) {
 107
 108                 if (table[i].frequency < freq)
 109                         continue;
 110
 111                 power = scale_pd_power_uw(pd_mask, table[i].power);
 112                 break;
 113         }
 114         rcu_read_unlock();
 115
 116         return power;
 117 }
 118
 119 static int update_pd_power_uw(struct dtpm *dtpm)
 120 {
 121         struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
 122         struct em_perf_domain *em = em_cpu_get(dtpm_cpu->cpu);
 123         struct em_perf_state *table;
 124         int nr_cpus;
 125
 126         nr_cpus = cpumask_weight_and(cpu_online_mask, to_cpumask(em->cpus));
 127
 128         rcu_read_lock();
 129         table = em_perf_state_from_pd(em);
 130
 131         dtpm->power_min = table[0].power;
 132         dtpm->power_min *= nr_cpus;
 133
 134         dtpm->power_max = table[em->nr_perf_states - 1].power;
 135         dtpm->power_max *= nr_cpus;
 136
 137         rcu_read_unlock();
 138
 139         return 0;
 140 }
 141
 142 static void pd_release(struct dtpm *dtpm)
 143 {
 144         struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
 145         struct cpufreq_policy *policy;
 146
 147         if (freq_qos_request_active(&dtpm_cpu->qos_req))
 148                 freq_qos_remove_request(&dtpm_cpu->qos_req);
 149
 150         policy = cpufreq_cpu_get(dtpm_cpu->cpu);
 151         if (policy) {
 152                 for_each_cpu(dtpm_cpu->cpu, policy->related_cpus)
 153                         per_cpu(dtpm_per_cpu, dtpm_cpu->cpu) = NULL;
 154
 155                 cpufreq_cpu_put(policy);
 156         }
 157
 158         kfree(dtpm_cpu);
 159 }
 160
 161 static struct dtpm_ops dtpm_ops = {
 162         .set_power_uw    = set_pd_power_limit,
 163         .get_power_uw    = get_pd_power_uw,
 164         .update_power_uw = update_pd_power_uw,
 165         .release         = pd_release,
 166 };
 167
 168 static int cpuhp_dtpm_cpu_offline(unsigned int cpu)
 169 {
 170         struct dtpm_cpu *dtpm_cpu;
 171
 172         dtpm_cpu = per_cpu(dtpm_per_cpu, cpu);
 173         if (dtpm_cpu)
 174                 dtpm_update_power(&dtpm_cpu->dtpm);
 175
 176         return 0;
 177 }
 178
 179 static int cpuhp_dtpm_cpu_online(unsigned int cpu)
 180 {
 181         struct dtpm_cpu *dtpm_cpu;
 182
 183         dtpm_cpu = per_cpu(dtpm_per_cpu, cpu);
 184         if (dtpm_cpu)
 185                 return dtpm_update_power(&dtpm_cpu->dtpm);
 186
 187         return 0;
 188 }
 189
 190 static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
 191 {
 192         struct dtpm_cpu *dtpm_cpu;
 193         struct cpufreq_policy *policy;
 194         struct em_perf_state *table;
 195         struct em_perf_domain *pd;
 196         char name[CPUFREQ_NAME_LEN];
 197         int ret = -ENOMEM;
 198
 199         dtpm_cpu = per_cpu(dtpm_per_cpu, cpu);
 200         if (dtpm_cpu)
 201                 return 0;
 202
 203         policy = cpufreq_cpu_get(cpu);
 204         if (!policy)
 205                 return 0;
 206
 207         pd = em_cpu_get(cpu);
 208         if (!pd || em_is_artificial(pd)) {
 209                 ret = -EINVAL;
 210                 goto release_policy;
 211         }
 212
 213         dtpm_cpu = kzalloc(sizeof(*dtpm_cpu), GFP_KERNEL);
 214         if (!dtpm_cpu) {
 215                 ret = -ENOMEM;
 216                 goto release_policy;
 217         }
 218
 219         dtpm_init(&dtpm_cpu->dtpm, &dtpm_ops);
 220         dtpm_cpu->cpu = cpu;
 221
 222         for_each_cpu(cpu, policy->related_cpus)
 223                 per_cpu(dtpm_per_cpu, cpu) = dtpm_cpu;
 224
 225         snprintf(name, sizeof(name), "cpu%d-cpufreq", dtpm_cpu->cpu);
 226
 227         ret = dtpm_register(name, &dtpm_cpu->dtpm, parent);
 228         if (ret)
 229                 goto out_kfree_dtpm_cpu;
 230
 231         rcu_read_lock();
 232         table = em_perf_state_from_pd(pd);
 233         ret = freq_qos_add_request(&policy->constraints,
 234                                    &dtpm_cpu->qos_req, FREQ_QOS_MAX,
 235                                    table[pd->nr_perf_states - 1].frequency);
 236         rcu_read_unlock();
 237         if (ret < 0)
 238                 goto out_dtpm_unregister;
 239
 240         cpufreq_cpu_put(policy);
 241         return 0;
 242
 243 out_dtpm_unregister:
 244         dtpm_unregister(&dtpm_cpu->dtpm);
 245         dtpm_cpu = NULL;
 246
 247 out_kfree_dtpm_cpu:
 248         for_each_cpu(cpu, policy->related_cpus)
 249                 per_cpu(dtpm_per_cpu, cpu) = NULL;
 250         kfree(dtpm_cpu);
 251
 252 release_policy:
 253         cpufreq_cpu_put(policy);
 254         return ret;
 255 }
 256
 257 static int dtpm_cpu_setup(struct dtpm *dtpm, struct device_node *np)
 258 {
 259         int cpu;
 260
 261         cpu = of_cpu_node_to_id(np);
 262         if (cpu < 0)
 263                 return 0;
 264
 265         return __dtpm_cpu_setup(cpu, dtpm);
 266 }
 267
 268 static int dtpm_cpu_init(void)
 269 {
 270         int ret;
 271
 272         /*
 273          * The callbacks at CPU hotplug time are calling
 274          * dtpm_update_power() which in turns calls update_pd_power().
 275          *
 276          * The function update_pd_power() uses the online mask to
 277          * figure out the power consumption limits.
 278          *
 279          * At CPUHP_AP_ONLINE_DYN, the CPU is present in the CPU
 280          * online mask when the cpuhp_dtpm_cpu_online function is
 281          * called, but the CPU is still in the online mask for the
 282          * tear down callback. So the power can not be updated when
 283          * the CPU is unplugged.
 284          *
 285          * At CPUHP_AP_DTPM_CPU_DEAD, the situation is the opposite as
 286          * above. The CPU online mask is not up to date when the CPU
 287          * is plugged in.
 288          *
 289          * For this reason, we need to call the online and offline
 290          * callbacks at different moments when the CPU online mask is
 291          * consistent with the power numbers we want to update.
 292          */
 293         ret = cpuhp_setup_state(CPUHP_AP_DTPM_CPU_DEAD, "dtpm_cpu:offline",
 294                                 NULL, cpuhp_dtpm_cpu_offline);
 295         if (ret < 0)
 296                 return ret;
 297
 298         ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "dtpm_cpu:online",
 299                                 cpuhp_dtpm_cpu_online, NULL);
 300         if (ret < 0)
 301                 return ret;
 302
 303         return 0;
 304 }
 305
 306 static void dtpm_cpu_exit(void)
 307 {
 308         cpuhp_remove_state_nocalls(CPUHP_AP_ONLINE_DYN);
 309         cpuhp_remove_state_nocalls(CPUHP_AP_DTPM_CPU_DEAD);
 310 }
 311
 312 struct dtpm_subsys_ops dtpm_cpu_ops = {
 313         .name = KBUILD_MODNAME,
 314         .init = dtpm_cpu_init,
 315         .exit = dtpm_cpu_exit,
 316         .setup = dtpm_cpu_setup,
 317 };