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