drivers/powercap/dtpm_cpu.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright 2020 Linaro Limited
   4  *
   5  * Author: Daniel Lezcano <[email protected]>
   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/pm_qos.h>
  25 #include <linux/slab.h>
  26 #include <linux/units.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 * MICROWATT_PER_MILLIWATT * 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 *
  66                 MICROWATT_PER_MILLIWATT * nr_cpus;
  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 = 0, sum_util = 0;
  74         int cpu;
  75
  76         for_each_cpu_and(cpu, pd_mask, cpu_online_mask) {
  77
  78                 /*
  79                  * The capacity is the same for all CPUs belonging to
  80                  * the same perf domain, so a single call to
  81                  * arch_scale_cpu_capacity() is enough. However, we
  82                  * need the CPU parameter to be initialized by the
  83                  * loop, so the call ends up in this block.
  84                  *
  85                  * We can initialize 'max' with a cpumask_first() call
  86                  * before the loop but the bits computation is not
  87                  * worth given the arch_scale_cpu_capacity() just
  88                  * returns a value where the resulting assembly code
  89                  * will be optimized by the compiler.
  90                  */
  91                 max = arch_scale_cpu_capacity(cpu);
  92                 sum_util += sched_cpu_util(cpu, max);
  93         }
  94
  95         /*
  96          * In the improbable case where all the CPUs of the perf
  97          * domain are offline, 'max' will be zero and will lead to an
  98          * illegal operation with a zero division.
  99          */
 100         return max ? (power * ((sum_util << 10) / max)) >> 10 : 0;
 101 }
 102
 103 static u64 get_pd_power_uw(struct dtpm *dtpm)
 104 {
 105         struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
 106         struct em_perf_domain *pd;
 107         struct cpumask *pd_mask;
 108         unsigned long freq;
 109         int i;
 110
 111         pd = em_cpu_get(dtpm_cpu->cpu);
 112
 113         pd_mask = em_span_cpus(pd);
 114
 115         freq = cpufreq_quick_get(dtpm_cpu->cpu);
 116
 117         for (i = 0; i < pd->nr_perf_states; i++) {
 118
 119                 if (pd->table[i].frequency < freq)
 120                         continue;
 121
 122                 return scale_pd_power_uw(pd_mask, pd->table[i].power *
 123                                          MICROWATT_PER_MILLIWATT);
 124         }
 125
 126         return 0;
 127 }
 128
 129 static int update_pd_power_uw(struct dtpm *dtpm)
 130 {
 131         struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
 132         struct em_perf_domain *em = em_cpu_get(dtpm_cpu->cpu);
 133         struct cpumask cpus;
 134         int nr_cpus;
 135
 136         cpumask_and(&cpus, cpu_online_mask, to_cpumask(em->cpus));
 137         nr_cpus = cpumask_weight(&cpus);
 138
 139         dtpm->power_min = em->table[0].power;
 140         dtpm->power_min *= MICROWATT_PER_MILLIWATT;
 141         dtpm->power_min *= nr_cpus;
 142
 143         dtpm->power_max = em->table[em->nr_perf_states - 1].power;
 144         dtpm->power_max *= MICROWATT_PER_MILLIWATT;
 145         dtpm->power_max *= nr_cpus;
 146
 147         return 0;
 148 }
 149
 150 static void pd_release(struct dtpm *dtpm)
 151 {
 152         struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
 153
 154         if (freq_qos_request_active(&dtpm_cpu->qos_req))
 155                 freq_qos_remove_request(&dtpm_cpu->qos_req);
 156
 157         kfree(dtpm_cpu);
 158 }
 159
 160 static struct dtpm_ops dtpm_ops = {
 161         .set_power_uw    = set_pd_power_limit,
 162         .get_power_uw    = get_pd_power_uw,
 163         .update_power_uw = update_pd_power_uw,
 164         .release         = pd_release,
 165 };
 166
 167 static int cpuhp_dtpm_cpu_offline(unsigned int cpu)
 168 {
 169         struct em_perf_domain *pd;
 170         struct dtpm_cpu *dtpm_cpu;
 171
 172         pd = em_cpu_get(cpu);
 173         if (!pd)
 174                 return -EINVAL;
 175
 176         dtpm_cpu = per_cpu(dtpm_per_cpu, cpu);
 177
 178         return dtpm_update_power(&dtpm_cpu->dtpm);
 179 }
 180
 181 static int cpuhp_dtpm_cpu_online(unsigned int cpu)
 182 {
 183         struct dtpm_cpu *dtpm_cpu;
 184         struct cpufreq_policy *policy;
 185         struct em_perf_domain *pd;
 186         char name[CPUFREQ_NAME_LEN];
 187         int ret = -ENOMEM;
 188
 189         policy = cpufreq_cpu_get(cpu);
 190         if (!policy)
 191                 return 0;
 192
 193         pd = em_cpu_get(cpu);
 194         if (!pd)
 195                 return -EINVAL;
 196
 197         dtpm_cpu = per_cpu(dtpm_per_cpu, cpu);
 198         if (dtpm_cpu)
 199                 return dtpm_update_power(&dtpm_cpu->dtpm);
 200
 201         dtpm_cpu = kzalloc(sizeof(*dtpm_cpu), GFP_KERNEL);
 202         if (!dtpm_cpu)
 203                 return -ENOMEM;
 204
 205         dtpm_init(&dtpm_cpu->dtpm, &dtpm_ops);
 206         dtpm_cpu->cpu = cpu;
 207
 208         for_each_cpu(cpu, policy->related_cpus)
 209                 per_cpu(dtpm_per_cpu, cpu) = dtpm_cpu;
 210
 211         snprintf(name, sizeof(name), "cpu%d-cpufreq", dtpm_cpu->cpu);
 212
 213         ret = dtpm_register(name, &dtpm_cpu->dtpm, NULL);
 214         if (ret)
 215                 goto out_kfree_dtpm_cpu;
 216
 217         ret = freq_qos_add_request(&policy->constraints,
 218                                    &dtpm_cpu->qos_req, FREQ_QOS_MAX,
 219                                    pd->table[pd->nr_perf_states - 1].frequency);
 220         if (ret)
 221                 goto out_dtpm_unregister;
 222
 223         return 0;
 224
 225 out_dtpm_unregister:
 226         dtpm_unregister(&dtpm_cpu->dtpm);
 227         dtpm_cpu = NULL;
 228
 229 out_kfree_dtpm_cpu:
 230         for_each_cpu(cpu, policy->related_cpus)
 231                 per_cpu(dtpm_per_cpu, cpu) = NULL;
 232         kfree(dtpm_cpu);
 233
 234         return ret;
 235 }
 236
 237 static int __init dtpm_cpu_init(void)
 238 {
 239         int ret;
 240
 241         /*
 242          * The callbacks at CPU hotplug time are calling
 243          * dtpm_update_power() which in turns calls update_pd_power().
 244          *
 245          * The function update_pd_power() uses the online mask to
 246          * figure out the power consumption limits.
 247          *
 248          * At CPUHP_AP_ONLINE_DYN, the CPU is present in the CPU
 249          * online mask when the cpuhp_dtpm_cpu_online function is
 250          * called, but the CPU is still in the online mask for the
 251          * tear down callback. So the power can not be updated when
 252          * the CPU is unplugged.
 253          *
 254          * At CPUHP_AP_DTPM_CPU_DEAD, the situation is the opposite as
 255          * above. The CPU online mask is not up to date when the CPU
 256          * is plugged in.
 257          *
 258          * For this reason, we need to call the online and offline
 259          * callbacks at different moments when the CPU online mask is
 260          * consistent with the power numbers we want to update.
 261          */
 262         ret = cpuhp_setup_state(CPUHP_AP_DTPM_CPU_DEAD, "dtpm_cpu:offline",
 263                                 NULL, cpuhp_dtpm_cpu_offline);
 264         if (ret < 0)
 265                 return ret;
 266
 267         ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "dtpm_cpu:online",
 268                                 cpuhp_dtpm_cpu_online, NULL);
 269         if (ret < 0)
 270                 return ret;
 271
 272         return 0;
 273 }
 274
 275 DTPM_DECLARE(dtpm_cpu, dtpm_cpu_init);