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