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 ARM Ltd.
   6  * Sudeep Holla <sudeep.holla@arm.com>
   7  */
   8
   9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  10
  11 #include <linux/cpu.h>
  12 #include <linux/cpufreq.h>
  13 #include <linux/cpumask.h>
  14 #include <linux/cpu_cooling.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         struct device *cpu_dev;
  26         struct thermal_cooling_device *cdev;
  27 };
  28
  29 static const struct scmi_handle *handle;
  30
  31 static unsigned int scmi_cpufreq_get_rate(unsigned int cpu)
  32 {
  33         struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
  34         struct scmi_perf_ops *perf_ops = handle->perf_ops;
  35         struct scmi_data *priv = policy->driver_data;
  36         unsigned long rate;
  37         int ret;
  38
  39         ret = perf_ops->freq_get(handle, priv->domain_id, &rate, false);
  40         if (ret)
  41                 return 0;
  42         return rate / 1000;
  43 }
  44
  45 /*
  46  * perf_ops->freq_set is not a synchronous, the actual OPP change will
  47  * happen asynchronously and can get notified if the events are
  48  * subscribed for by the SCMI firmware
  49  */
  50 static int
  51 scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
  52 {
  53         int ret;
  54         struct scmi_data *priv = policy->driver_data;
  55         struct scmi_perf_ops *perf_ops = handle->perf_ops;
  56         u64 freq = policy->freq_table[index].frequency;
  57
  58         ret = perf_ops->freq_set(handle, priv->domain_id, freq * 1000, false);
  59         if (!ret)
  60                 arch_set_freq_scale(policy->related_cpus, freq,
  61                                     policy->cpuinfo.max_freq);
  62         return ret;
  63 }
  64
  65 static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy,
  66                                              unsigned int target_freq)
  67 {
  68         struct scmi_data *priv = policy->driver_data;
  69         struct scmi_perf_ops *perf_ops = handle->perf_ops;
  70
  71         if (!perf_ops->freq_set(handle, priv->domain_id,
  72                                 target_freq * 1000, true)) {
  73                 arch_set_freq_scale(policy->related_cpus, target_freq,
  74                                     policy->cpuinfo.max_freq);
  75                 return target_freq;
  76         }
  77
  78         return 0;
  79 }
  80
  81 static int
  82 scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
  83 {
  84         int cpu, domain, tdomain;
  85         struct device *tcpu_dev;
  86
  87         domain = handle->perf_ops->device_domain_id(cpu_dev);
  88         if (domain < 0)
  89                 return domain;
  90
  91         for_each_possible_cpu(cpu) {
  92                 if (cpu == cpu_dev->id)
  93                         continue;
  94
  95                 tcpu_dev = get_cpu_device(cpu);
  96                 if (!tcpu_dev)
  97                         continue;
  98
  99                 tdomain = handle->perf_ops->device_domain_id(tcpu_dev);
 100                 if (tdomain == domain)
 101                         cpumask_set_cpu(cpu, cpumask);
 102         }
 103
 104         return 0;
 105 }
 106
 107 static int __maybe_unused
 108 scmi_get_cpu_power(unsigned long *power, unsigned long *KHz, int cpu)
 109 {
 110         struct device *cpu_dev = get_cpu_device(cpu);
 111         unsigned long Hz;
 112         int ret, domain;
 113
 114         if (!cpu_dev) {
 115                 pr_err("failed to get cpu%d device\n", cpu);
 116                 return -ENODEV;
 117         }
 118
 119         domain = handle->perf_ops->device_domain_id(cpu_dev);
 120         if (domain < 0)
 121                 return domain;
 122
 123         /* Get the power cost of the performance domain. */
 124         Hz = *KHz * 1000;
 125         ret = handle->perf_ops->est_power_get(handle, domain, &Hz, power);
 126         if (ret)
 127                 return ret;
 128
 129         /* The EM framework specifies the frequency in KHz. */
 130         *KHz = Hz / 1000;
 131
 132         return 0;
 133 }
 134
 135 static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 136 {
 137         int ret, nr_opp;
 138         unsigned int latency;
 139         struct device *cpu_dev;
 140         struct scmi_data *priv;
 141         struct cpufreq_frequency_table *freq_table;
 142         struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
 143
 144         cpu_dev = get_cpu_device(policy->cpu);
 145         if (!cpu_dev) {
 146                 pr_err("failed to get cpu%d device\n", policy->cpu);
 147                 return -ENODEV;
 148         }
 149
 150         ret = handle->perf_ops->device_opps_add(handle, cpu_dev);
 151         if (ret) {
 152                 dev_warn(cpu_dev, "failed to add opps to the device\n");
 153                 return ret;
 154         }
 155
 156         ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus);
 157         if (ret) {
 158                 dev_warn(cpu_dev, "failed to get sharing cpumask\n");
 159                 return ret;
 160         }
 161
 162         ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus);
 163         if (ret) {
 164                 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
 165                         __func__, ret);
 166                 return ret;
 167         }
 168
 169         nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
 170         if (nr_opp <= 0) {
 171                 dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n");
 172                 ret = -EPROBE_DEFER;
 173                 goto out_free_opp;
 174         }
 175
 176         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 177         if (!priv) {
 178                 ret = -ENOMEM;
 179                 goto out_free_opp;
 180         }
 181
 182         ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
 183         if (ret) {
 184                 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
 185                 goto out_free_priv;
 186         }
 187
 188         priv->cpu_dev = cpu_dev;
 189         priv->domain_id = handle->perf_ops->device_domain_id(cpu_dev);
 190
 191         policy->driver_data = priv;
 192         policy->freq_table = freq_table;
 193
 194         /* SCMI allows DVFS request for any domain from any CPU */
 195         policy->dvfs_possible_from_any_cpu = true;
 196
 197         latency = handle->perf_ops->transition_latency_get(handle, cpu_dev);
 198         if (!latency)
 199                 latency = CPUFREQ_ETERNAL;
 200
 201         policy->cpuinfo.transition_latency = latency;
 202
 203         policy->fast_switch_possible = true;
 204
 205         em_register_perf_domain(policy->cpus, nr_opp, &em_cb);
 206
 207         return 0;
 208
 209 out_free_priv:
 210         kfree(priv);
 211 out_free_opp:
 212         dev_pm_opp_remove_all_dynamic(cpu_dev);
 213
 214         return ret;
 215 }
 216
 217 static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
 218 {
 219         struct scmi_data *priv = policy->driver_data;
 220
 221         cpufreq_cooling_unregister(priv->cdev);
 222         dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
 223         kfree(priv);
 224         dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
 225
 226         return 0;
 227 }
 228
 229 static void scmi_cpufreq_ready(struct cpufreq_policy *policy)
 230 {
 231         struct scmi_data *priv = policy->driver_data;
 232
 233         priv->cdev = of_cpufreq_cooling_register(policy);
 234 }
 235
 236 static struct cpufreq_driver scmi_cpufreq_driver = {
 237         .name   = "scmi",
 238         .flags  = CPUFREQ_STICKY | CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
 239                   CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 240         .verify = cpufreq_generic_frequency_table_verify,
 241         .attr   = cpufreq_generic_attr,
 242         .target_index   = scmi_cpufreq_set_target,
 243         .fast_switch    = scmi_cpufreq_fast_switch,
 244         .get    = scmi_cpufreq_get_rate,
 245         .init   = scmi_cpufreq_init,
 246         .exit   = scmi_cpufreq_exit,
 247         .ready  = scmi_cpufreq_ready,
 248 };
 249
 250 static int scmi_cpufreq_probe(struct scmi_device *sdev)
 251 {
 252         int ret;
 253
 254         handle = sdev->handle;
 255
 256         if (!handle || !handle->perf_ops)
 257                 return -ENODEV;
 258
 259         ret = cpufreq_register_driver(&scmi_cpufreq_driver);
 260         if (ret) {
 261                 dev_err(&sdev->dev, "%s: registering cpufreq failed, err: %d\n",
 262                         __func__, ret);
 263         }
 264
 265         return ret;
 266 }
 267
 268 static void scmi_cpufreq_remove(struct scmi_device *sdev)
 269 {
 270         cpufreq_unregister_driver(&scmi_cpufreq_driver);
 271 }
 272
 273 static const struct scmi_device_id scmi_id_table[] = {
 274         { SCMI_PROTOCOL_PERF },
 275         { },
 276 };
 277 MODULE_DEVICE_TABLE(scmi, scmi_id_table);
 278
 279 static struct scmi_driver scmi_cpufreq_drv = {
 280         .name           = "scmi-cpufreq",
 281         .probe          = scmi_cpufreq_probe,
 282         .remove         = scmi_cpufreq_remove,
 283         .id_table       = scmi_id_table,
 284 };
 285 module_scmi_driver(scmi_cpufreq_drv);
 286
 287 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
 288 MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
 289 MODULE_LICENSE("GPL v2");