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