drivers/cpufreq/scmi-cpufreq.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * System Control and Power Interface (SCMI) based CPUFreq Interface driver
   4  *
   5  * Copyright (C) 2018-2021 ARM Ltd.
   6  * Sudeep Holla <sudeep.holla@arm.com>
   7  */
   8
   9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  10
  11 #include <linux/clk-provider.h>
  12 #include <linux/cpu.h>
  13 #include <linux/cpufreq.h>
  14 #include <linux/cpumask.h>
  15 #include <linux/energy_model.h>
  16 #include <linux/export.h>
  17 #include <linux/module.h>
  18 #include <linux/pm_opp.h>
  19 #include <linux/slab.h>
  20 #include <linux/scmi_protocol.h>
  21 #include <linux/types.h>
  22 #include <linux/units.h>
  23
  24 struct scmi_data {
  25         int domain_id;
  26         int nr_opp;
  27         struct device *cpu_dev;
  28         cpumask_var_t opp_shared_cpus;
  29 };
  30
  31 static struct scmi_protocol_handle *ph;
  32 static const struct scmi_perf_proto_ops *perf_ops;
  33 static struct cpufreq_driver scmi_cpufreq_driver;
  34
  35 static unsigned int scmi_cpufreq_get_rate(unsigned int cpu)
  36 {
  37         struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
  38         struct scmi_data *priv = policy->driver_data;
  39         unsigned long rate;
  40         int ret;
  41
  42         ret = perf_ops->freq_get(ph, priv->domain_id, &rate, false);
  43         if (ret)
  44                 return 0;
  45         return rate / 1000;
  46 }
  47
  48 /*
  49  * perf_ops->freq_set is not a synchronous, the actual OPP change will
  50  * happen asynchronously and can get notified if the events are
  51  * subscribed for by the SCMI firmware
  52  */
  53 static int
  54 scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
  55 {
  56         struct scmi_data *priv = policy->driver_data;
  57         u64 freq = policy->freq_table[index].frequency;
  58
  59         return perf_ops->freq_set(ph, priv->domain_id, freq * 1000, false);
  60 }
  61
  62 static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy,
  63                                              unsigned int target_freq)
  64 {
  65         struct scmi_data *priv = policy->driver_data;
  66
  67         if (!perf_ops->freq_set(ph, priv->domain_id,
  68                                 target_freq * 1000, true))
  69                 return target_freq;
  70
  71         return 0;
  72 }
  73
  74 static int scmi_cpu_domain_id(struct device *cpu_dev)
  75 {
  76         struct device_node *np = cpu_dev->of_node;
  77         struct of_phandle_args domain_id;
  78         int index;
  79
  80         if (of_parse_phandle_with_args(np, "clocks", "#clock-cells", 0,
  81                                        &domain_id)) {
  82                 /* Find the corresponding index for power-domain "perf". */
  83                 index = of_property_match_string(np, "power-domain-names",
  84                                                  "perf");
  85                 if (index < 0)
  86                         return -EINVAL;
  87
  88                 if (of_parse_phandle_with_args(np, "power-domains",
  89                                                "#power-domain-cells", index,
  90                                                &domain_id))
  91                         return -EINVAL;
  92         }
  93
  94         return domain_id.args[0];
  95 }
  96
  97 static int
  98 scmi_get_sharing_cpus(struct device *cpu_dev, int domain,
  99                       struct cpumask *cpumask)
 100 {
 101         int cpu, tdomain;
 102         struct device *tcpu_dev;
 103
 104         for_each_possible_cpu(cpu) {
 105                 if (cpu == cpu_dev->id)
 106                         continue;
 107
 108                 tcpu_dev = get_cpu_device(cpu);
 109                 if (!tcpu_dev)
 110                         continue;
 111
 112                 tdomain = scmi_cpu_domain_id(tcpu_dev);
 113                 if (tdomain == domain)
 114                         cpumask_set_cpu(cpu, cpumask);
 115         }
 116
 117         return 0;
 118 }
 119
 120 static int __maybe_unused
 121 scmi_get_cpu_power(struct device *cpu_dev, unsigned long *power,
 122                    unsigned long *KHz)
 123 {
 124         enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph);
 125         unsigned long Hz;
 126         int ret, domain;
 127
 128         domain = scmi_cpu_domain_id(cpu_dev);
 129         if (domain < 0)
 130                 return domain;
 131
 132         /* Get the power cost of the performance domain. */
 133         Hz = *KHz * 1000;
 134         ret = perf_ops->est_power_get(ph, domain, &Hz, power);
 135         if (ret)
 136                 return ret;
 137
 138         /* Convert the power to uW if it is mW (ignore bogoW) */
 139         if (power_scale == SCMI_POWER_MILLIWATTS)
 140                 *power *= MICROWATT_PER_MILLIWATT;
 141
 142         /* The EM framework specifies the frequency in KHz. */
 143         *KHz = Hz / 1000;
 144
 145         return 0;
 146 }
 147
 148 static int
 149 scmi_get_rate_limit(u32 domain, bool has_fast_switch)
 150 {
 151         int ret, rate_limit;
 152
 153         if (has_fast_switch) {
 154                 /*
 155                  * Fast channels are used whenever available,
 156                  * so use their rate_limit value if populated.
 157                  */
 158                 ret = perf_ops->fast_switch_rate_limit(ph, domain,
 159                                                        &rate_limit);
 160                 if (!ret && rate_limit)
 161                         return rate_limit;
 162         }
 163
 164         ret = perf_ops->rate_limit_get(ph, domain, &rate_limit);
 165         if (ret)
 166                 return 0;
 167
 168         return rate_limit;
 169 }
 170
 171 static struct freq_attr *scmi_cpufreq_hw_attr[] = {
 172         &cpufreq_freq_attr_scaling_available_freqs,
 173         NULL,
 174         NULL,
 175 };
 176
 177 static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 178 {
 179         int ret, nr_opp, domain;
 180         unsigned int latency;
 181         struct device *cpu_dev;
 182         struct scmi_data *priv;
 183         struct cpufreq_frequency_table *freq_table;
 184
 185         cpu_dev = get_cpu_device(policy->cpu);
 186         if (!cpu_dev) {
 187                 pr_err("failed to get cpu%d device\n", policy->cpu);
 188                 return -ENODEV;
 189         }
 190
 191         domain = scmi_cpu_domain_id(cpu_dev);
 192         if (domain < 0)
 193                 return domain;
 194
 195         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 196         if (!priv)
 197                 return -ENOMEM;
 198
 199         if (!zalloc_cpumask_var(&priv->opp_shared_cpus, GFP_KERNEL)) {
 200                 ret = -ENOMEM;
 201                 goto out_free_priv;
 202         }
 203
 204         /* Obtain CPUs that share SCMI performance controls */
 205         ret = scmi_get_sharing_cpus(cpu_dev, domain, policy->cpus);
 206         if (ret) {
 207                 dev_warn(cpu_dev, "failed to get sharing cpumask\n");
 208                 goto out_free_cpumask;
 209         }
 210
 211         /*
 212          * Obtain CPUs that share performance levels.
 213          * The OPP 'sharing cpus' info may come from DT through an empty opp
 214          * table and opp-shared.
 215          */
 216         ret = dev_pm_opp_of_get_sharing_cpus(cpu_dev, priv->opp_shared_cpus);
 217         if (ret || cpumask_empty(priv->opp_shared_cpus)) {
 218                 /*
 219                  * Either opp-table is not set or no opp-shared was found.
 220                  * Use the CPU mask from SCMI to designate CPUs sharing an OPP
 221                  * table.
 222                  */
 223                 cpumask_copy(priv->opp_shared_cpus, policy->cpus);
 224         }
 225
 226          /*
 227           * A previous CPU may have marked OPPs as shared for a few CPUs, based on
 228           * what OPP core provided. If the current CPU is part of those few, then
 229           * there is no need to add OPPs again.
 230           */
 231         nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
 232         if (nr_opp <= 0) {
 233                 ret = perf_ops->device_opps_add(ph, cpu_dev, domain);
 234                 if (ret) {
 235                         dev_warn(cpu_dev, "failed to add opps to the device\n");
 236                         goto out_free_cpumask;
 237                 }
 238
 239                 nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
 240                 if (nr_opp <= 0) {
 241                         dev_err(cpu_dev, "%s: No OPPs for this device: %d\n",
 242                                 __func__, nr_opp);
 243
 244                         ret = -ENODEV;
 245                         goto out_free_opp;
 246                 }
 247
 248                 ret = dev_pm_opp_set_sharing_cpus(cpu_dev, priv->opp_shared_cpus);
 249                 if (ret) {
 250                         dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
 251                                 __func__, ret);
 252
 253                         goto out_free_opp;
 254                 }
 255
 256                 priv->nr_opp = nr_opp;
 257         }
 258
 259         ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
 260         if (ret) {
 261                 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
 262                 goto out_free_opp;
 263         }
 264
 265         priv->cpu_dev = cpu_dev;
 266         priv->domain_id = domain;
 267
 268         policy->driver_data = priv;
 269         policy->freq_table = freq_table;
 270
 271         /* SCMI allows DVFS request for any domain from any CPU */
 272         policy->dvfs_possible_from_any_cpu = true;
 273
 274         latency = perf_ops->transition_latency_get(ph, domain);
 275         if (!latency)
 276                 latency = CPUFREQ_ETERNAL;
 277
 278         policy->cpuinfo.transition_latency = latency;
 279
 280         policy->fast_switch_possible =
 281                 perf_ops->fast_switch_possible(ph, domain);
 282
 283         policy->transition_delay_us =
 284                 scmi_get_rate_limit(domain, policy->fast_switch_possible);
 285
 286         if (policy_has_boost_freq(policy)) {
 287                 ret = cpufreq_enable_boost_support();
 288                 if (ret) {
 289                         dev_warn(cpu_dev, "failed to enable boost: %d\n", ret);
 290                         goto out_free_opp;
 291                 } else {
 292                         scmi_cpufreq_hw_attr[1] = &cpufreq_freq_attr_scaling_boost_freqs;
 293                         scmi_cpufreq_driver.boost_enabled = true;
 294                 }
 295         }
 296
 297         return 0;
 298
 299 out_free_opp:
 300         dev_pm_opp_remove_all_dynamic(cpu_dev);
 301
 302 out_free_cpumask:
 303         free_cpumask_var(priv->opp_shared_cpus);
 304
 305 out_free_priv:
 306         kfree(priv);
 307
 308         return ret;
 309 }
 310
 311 static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
 312 {
 313         struct scmi_data *priv = policy->driver_data;
 314
 315         dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
 316         dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
 317         free_cpumask_var(priv->opp_shared_cpus);
 318         kfree(priv);
 319
 320         return 0;
 321 }
 322
 323 static void scmi_cpufreq_register_em(struct cpufreq_policy *policy)
 324 {
 325         struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
 326         enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph);
 327         struct scmi_data *priv = policy->driver_data;
 328         bool em_power_scale = false;
 329
 330         /*
 331          * This callback will be called for each policy, but we don't need to
 332          * register with EM every time. Despite not being part of the same
 333          * policy, some CPUs may still share their perf-domains, and a CPU from
 334          * another policy may already have registered with EM on behalf of CPUs
 335          * of this policy.
 336          */
 337         if (!priv->nr_opp)
 338                 return;
 339
 340         if (power_scale == SCMI_POWER_MILLIWATTS
 341             || power_scale == SCMI_POWER_MICROWATTS)
 342                 em_power_scale = true;
 343
 344         em_dev_register_perf_domain(get_cpu_device(policy->cpu), priv->nr_opp,
 345                                     &em_cb, priv->opp_shared_cpus,
 346                                     em_power_scale);
 347 }
 348
 349 static struct cpufreq_driver scmi_cpufreq_driver = {
 350         .name   = "scmi",
 351         .flags  = CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
 352                   CPUFREQ_NEED_INITIAL_FREQ_CHECK |
 353                   CPUFREQ_IS_COOLING_DEV,
 354         .verify = cpufreq_generic_frequency_table_verify,
 355         .attr   = scmi_cpufreq_hw_attr,
 356         .target_index   = scmi_cpufreq_set_target,
 357         .fast_switch    = scmi_cpufreq_fast_switch,
 358         .get    = scmi_cpufreq_get_rate,
 359         .init   = scmi_cpufreq_init,
 360         .exit   = scmi_cpufreq_exit,
 361         .register_em    = scmi_cpufreq_register_em,
 362 };
 363
 364 static int scmi_cpufreq_probe(struct scmi_device *sdev)
 365 {
 366         int ret;
 367         struct device *dev = &sdev->dev;
 368         const struct scmi_handle *handle;
 369
 370         handle = sdev->handle;
 371
 372         if (!handle)
 373                 return -ENODEV;
 374
 375         perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
 376         if (IS_ERR(perf_ops))
 377                 return PTR_ERR(perf_ops);
 378
 379 #ifdef CONFIG_COMMON_CLK
 380         /* dummy clock provider as needed by OPP if clocks property is used */
 381         if (of_property_present(dev->of_node, "#clock-cells")) {
 382                 ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, NULL);
 383                 if (ret)
 384                         return dev_err_probe(dev, ret, "%s: registering clock provider failed\n", __func__);
 385         }
 386 #endif
 387
 388         ret = cpufreq_register_driver(&scmi_cpufreq_driver);
 389         if (ret) {
 390                 dev_err(dev, "%s: registering cpufreq failed, err: %d\n",
 391                         __func__, ret);
 392         }
 393
 394         return ret;
 395 }
 396
 397 static void scmi_cpufreq_remove(struct scmi_device *sdev)
 398 {
 399         cpufreq_unregister_driver(&scmi_cpufreq_driver);
 400 }
 401
 402 static const struct scmi_device_id scmi_id_table[] = {
 403         { SCMI_PROTOCOL_PERF, "cpufreq" },
 404         { },
 405 };
 406 MODULE_DEVICE_TABLE(scmi, scmi_id_table);
 407
 408 static struct scmi_driver scmi_cpufreq_drv = {
 409         .name           = "scmi-cpufreq",
 410         .probe          = scmi_cpufreq_probe,
 411         .remove         = scmi_cpufreq_remove,
 412         .id_table       = scmi_id_table,
 413 };
 414 module_scmi_driver(scmi_cpufreq_drv);
 415
 416 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
 417 MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
 418 MODULE_LICENSE("GPL v2");