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
  23 struct scmi_data {
  24         int domain_id;
  25         int nr_opp;
  26         struct device *cpu_dev;
  27         cpumask_var_t opp_shared_cpus;
  28 };
  29
  30 static struct scmi_protocol_handle *ph;
  31 static const struct scmi_perf_proto_ops *perf_ops;
  32
  33 static unsigned int scmi_cpufreq_get_rate(unsigned int cpu)
  34 {
  35         struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
  36         struct scmi_data *priv = policy->driver_data;
  37         unsigned long rate;
  38         int ret;
  39
  40         ret = perf_ops->freq_get(ph, priv->domain_id, &rate, false);
  41         if (ret)
  42                 return 0;
  43         return rate / 1000;
  44 }
  45
  46 /*
  47  * perf_ops->freq_set is not a synchronous, the actual OPP change will
  48  * happen asynchronously and can get notified if the events are
  49  * subscribed for by the SCMI firmware
  50  */
  51 static int
  52 scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
  53 {
  54         struct scmi_data *priv = policy->driver_data;
  55         u64 freq = policy->freq_table[index].frequency;
  56
  57         return perf_ops->freq_set(ph, priv->domain_id, freq * 1000, false);
  58 }
  59
  60 static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy,
  61                                              unsigned int target_freq)
  62 {
  63         struct scmi_data *priv = policy->driver_data;
  64
  65         if (!perf_ops->freq_set(ph, priv->domain_id,
  66                                 target_freq * 1000, true))
  67                 return target_freq;
  68
  69         return 0;
  70 }
  71
  72 static int
  73 scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
  74 {
  75         int cpu, domain, tdomain;
  76         struct device *tcpu_dev;
  77
  78         domain = perf_ops->device_domain_id(cpu_dev);
  79         if (domain < 0)
  80                 return domain;
  81
  82         for_each_possible_cpu(cpu) {
  83                 if (cpu == cpu_dev->id)
  84                         continue;
  85
  86                 tcpu_dev = get_cpu_device(cpu);
  87                 if (!tcpu_dev)
  88                         continue;
  89
  90                 tdomain = perf_ops->device_domain_id(tcpu_dev);
  91                 if (tdomain == domain)
  92                         cpumask_set_cpu(cpu, cpumask);
  93         }
  94
  95         return 0;
  96 }
  97
  98 static int __maybe_unused
  99 scmi_get_cpu_power(struct device *cpu_dev, unsigned long *power,
 100                    unsigned long *KHz)
 101 {
 102         unsigned long Hz;
 103         int ret, domain;
 104
 105         domain = perf_ops->device_domain_id(cpu_dev);
 106         if (domain < 0)
 107                 return domain;
 108
 109         /* Get the power cost of the performance domain. */
 110         Hz = *KHz * 1000;
 111         ret = perf_ops->est_power_get(ph, domain, &Hz, power);
 112         if (ret)
 113                 return ret;
 114
 115         /* The EM framework specifies the frequency in KHz. */
 116         *KHz = Hz / 1000;
 117
 118         return 0;
 119 }
 120
 121 static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 122 {
 123         int ret, nr_opp;
 124         unsigned int latency;
 125         struct device *cpu_dev;
 126         struct scmi_data *priv;
 127         struct cpufreq_frequency_table *freq_table;
 128
 129         cpu_dev = get_cpu_device(policy->cpu);
 130         if (!cpu_dev) {
 131                 pr_err("failed to get cpu%d device\n", policy->cpu);
 132                 return -ENODEV;
 133         }
 134
 135         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 136         if (!priv)
 137                 return -ENOMEM;
 138
 139         if (!zalloc_cpumask_var(&priv->opp_shared_cpus, GFP_KERNEL)) {
 140                 ret = -ENOMEM;
 141                 goto out_free_priv;
 142         }
 143
 144         /* Obtain CPUs that share SCMI performance controls */
 145         ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus);
 146         if (ret) {
 147                 dev_warn(cpu_dev, "failed to get sharing cpumask\n");
 148                 goto out_free_cpumask;
 149         }
 150
 151         /*
 152          * Obtain CPUs that share performance levels.
 153          * The OPP 'sharing cpus' info may come from DT through an empty opp
 154          * table and opp-shared.
 155          */
 156         ret = dev_pm_opp_of_get_sharing_cpus(cpu_dev, priv->opp_shared_cpus);
 157         if (ret || cpumask_empty(priv->opp_shared_cpus)) {
 158                 /*
 159                  * Either opp-table is not set or no opp-shared was found.
 160                  * Use the CPU mask from SCMI to designate CPUs sharing an OPP
 161                  * table.
 162                  */
 163                 cpumask_copy(priv->opp_shared_cpus, policy->cpus);
 164         }
 165
 166          /*
 167           * A previous CPU may have marked OPPs as shared for a few CPUs, based on
 168           * what OPP core provided. If the current CPU is part of those few, then
 169           * there is no need to add OPPs again.
 170           */
 171         nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
 172         if (nr_opp <= 0) {
 173                 ret = perf_ops->device_opps_add(ph, cpu_dev);
 174                 if (ret) {
 175                         dev_warn(cpu_dev, "failed to add opps to the device\n");
 176                         goto out_free_cpumask;
 177                 }
 178
 179                 nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
 180                 if (nr_opp <= 0) {
 181                         dev_err(cpu_dev, "%s: No OPPs for this device: %d\n",
 182                                 __func__, nr_opp);
 183
 184                         ret = -ENODEV;
 185                         goto out_free_opp;
 186                 }
 187
 188                 ret = dev_pm_opp_set_sharing_cpus(cpu_dev, priv->opp_shared_cpus);
 189                 if (ret) {
 190                         dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
 191                                 __func__, ret);
 192
 193                         goto out_free_opp;
 194                 }
 195
 196                 priv->nr_opp = nr_opp;
 197         }
 198
 199         ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
 200         if (ret) {
 201                 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
 202                 goto out_free_opp;
 203         }
 204
 205         priv->cpu_dev = cpu_dev;
 206         priv->domain_id = perf_ops->device_domain_id(cpu_dev);
 207
 208         policy->driver_data = priv;
 209         policy->freq_table = freq_table;
 210
 211         /* SCMI allows DVFS request for any domain from any CPU */
 212         policy->dvfs_possible_from_any_cpu = true;
 213
 214         latency = perf_ops->transition_latency_get(ph, cpu_dev);
 215         if (!latency)
 216                 latency = CPUFREQ_ETERNAL;
 217
 218         policy->cpuinfo.transition_latency = latency;
 219
 220         policy->fast_switch_possible =
 221                 perf_ops->fast_switch_possible(ph, cpu_dev);
 222
 223         return 0;
 224
 225 out_free_opp:
 226         dev_pm_opp_remove_all_dynamic(cpu_dev);
 227
 228 out_free_cpumask:
 229         free_cpumask_var(priv->opp_shared_cpus);
 230
 231 out_free_priv:
 232         kfree(priv);
 233
 234         return ret;
 235 }
 236
 237 static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
 238 {
 239         struct scmi_data *priv = policy->driver_data;
 240
 241         dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
 242         dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
 243         free_cpumask_var(priv->opp_shared_cpus);
 244         kfree(priv);
 245
 246         return 0;
 247 }
 248
 249 static void scmi_cpufreq_register_em(struct cpufreq_policy *policy)
 250 {
 251         struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
 252         bool power_scale_mw = perf_ops->power_scale_mw_get(ph);
 253         struct scmi_data *priv = policy->driver_data;
 254
 255         /*
 256          * This callback will be called for each policy, but we don't need to
 257          * register with EM every time. Despite not being part of the same
 258          * policy, some CPUs may still share their perf-domains, and a CPU from
 259          * another policy may already have registered with EM on behalf of CPUs
 260          * of this policy.
 261          */
 262         if (!priv->nr_opp)
 263                 return;
 264
 265         em_dev_register_perf_domain(get_cpu_device(policy->cpu), priv->nr_opp,
 266                                     &em_cb, priv->opp_shared_cpus,
 267                                     power_scale_mw);
 268 }
 269
 270 static struct cpufreq_driver scmi_cpufreq_driver = {
 271         .name   = "scmi",
 272         .flags  = CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
 273                   CPUFREQ_NEED_INITIAL_FREQ_CHECK |
 274                   CPUFREQ_IS_COOLING_DEV,
 275         .verify = cpufreq_generic_frequency_table_verify,
 276         .attr   = cpufreq_generic_attr,
 277         .target_index   = scmi_cpufreq_set_target,
 278         .fast_switch    = scmi_cpufreq_fast_switch,
 279         .get    = scmi_cpufreq_get_rate,
 280         .init   = scmi_cpufreq_init,
 281         .exit   = scmi_cpufreq_exit,
 282         .register_em    = scmi_cpufreq_register_em,
 283 };
 284
 285 static int scmi_cpufreq_probe(struct scmi_device *sdev)
 286 {
 287         int ret;
 288         struct device *dev = &sdev->dev;
 289         const struct scmi_handle *handle;
 290
 291         handle = sdev->handle;
 292
 293         if (!handle)
 294                 return -ENODEV;
 295
 296         perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
 297         if (IS_ERR(perf_ops))
 298                 return PTR_ERR(perf_ops);
 299
 300 #ifdef CONFIG_COMMON_CLK
 301         /* dummy clock provider as needed by OPP if clocks property is used */
 302         if (of_find_property(dev->of_node, "#clock-cells", NULL))
 303                 devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, NULL);
 304 #endif
 305
 306         ret = cpufreq_register_driver(&scmi_cpufreq_driver);
 307         if (ret) {
 308                 dev_err(dev, "%s: registering cpufreq failed, err: %d\n",
 309                         __func__, ret);
 310         }
 311
 312         return ret;
 313 }
 314
 315 static void scmi_cpufreq_remove(struct scmi_device *sdev)
 316 {
 317         cpufreq_unregister_driver(&scmi_cpufreq_driver);
 318 }
 319
 320 static const struct scmi_device_id scmi_id_table[] = {
 321         { SCMI_PROTOCOL_PERF, "cpufreq" },
 322         { },
 323 };
 324 MODULE_DEVICE_TABLE(scmi, scmi_id_table);
 325
 326 static struct scmi_driver scmi_cpufreq_drv = {
 327         .name           = "scmi-cpufreq",
 328         .probe          = scmi_cpufreq_probe,
 329         .remove         = scmi_cpufreq_remove,
 330         .id_table       = scmi_id_table,
 331 };
 332 module_scmi_driver(scmi_cpufreq_drv);
 333
 334 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
 335 MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
 336 MODULE_LICENSE("GPL v2");