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/energy_model.h>
  15 #include <linux/export.h>
  16 #include <linux/module.h>
  17 #include <linux/pm_opp.h>
  18 #include <linux/slab.h>
  19 #include <linux/scmi_protocol.h>
  20 #include <linux/types.h>
  21
  22 struct scmi_data {
  23         int domain_id;
  24         struct device *cpu_dev;
  25 };
  26
  27 static const struct scmi_handle *handle;
  28
  29 static unsigned int scmi_cpufreq_get_rate(unsigned int cpu)
  30 {
  31         struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
  32         struct scmi_perf_ops *perf_ops = handle->perf_ops;
  33         struct scmi_data *priv = policy->driver_data;
  34         unsigned long rate;
  35         int ret;
  36
  37         ret = perf_ops->freq_get(handle, priv->domain_id, &rate, false);
  38         if (ret)
  39                 return 0;
  40         return rate / 1000;
  41 }
  42
  43 /*
  44  * perf_ops->freq_set is not a synchronous, the actual OPP change will
  45  * happen asynchronously and can get notified if the events are
  46  * subscribed for by the SCMI firmware
  47  */
  48 static int
  49 scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
  50 {
  51         int ret;
  52         struct scmi_data *priv = policy->driver_data;
  53         struct scmi_perf_ops *perf_ops = handle->perf_ops;
  54         u64 freq = policy->freq_table[index].frequency;
  55
  56         ret = perf_ops->freq_set(handle, priv->domain_id, freq * 1000, false);
  57         if (!ret)
  58                 arch_set_freq_scale(policy->related_cpus, freq,
  59                                     policy->cpuinfo.max_freq);
  60         return ret;
  61 }
  62
  63 static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy,
  64                                              unsigned int target_freq)
  65 {
  66         struct scmi_data *priv = policy->driver_data;
  67         struct scmi_perf_ops *perf_ops = handle->perf_ops;
  68
  69         if (!perf_ops->freq_set(handle, priv->domain_id,
  70                                 target_freq * 1000, true)) {
  71                 arch_set_freq_scale(policy->related_cpus, target_freq,
  72                                     policy->cpuinfo.max_freq);
  73                 return target_freq;
  74         }
  75
  76         return 0;
  77 }
  78
  79 static int
  80 scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
  81 {
  82         int cpu, domain, tdomain;
  83         struct device *tcpu_dev;
  84
  85         domain = handle->perf_ops->device_domain_id(cpu_dev);
  86         if (domain < 0)
  87                 return domain;
  88
  89         for_each_possible_cpu(cpu) {
  90                 if (cpu == cpu_dev->id)
  91                         continue;
  92
  93                 tcpu_dev = get_cpu_device(cpu);
  94                 if (!tcpu_dev)
  95                         continue;
  96
  97                 tdomain = handle->perf_ops->device_domain_id(tcpu_dev);
  98                 if (tdomain == domain)
  99                         cpumask_set_cpu(cpu, cpumask);
 100         }
 101
 102         return 0;
 103 }
 104
 105 static int __maybe_unused
 106 scmi_get_cpu_power(unsigned long *power, unsigned long *KHz, int cpu)
 107 {
 108         struct device *cpu_dev = get_cpu_device(cpu);
 109         unsigned long Hz;
 110         int ret, domain;
 111
 112         if (!cpu_dev) {
 113                 pr_err("failed to get cpu%d device\n", cpu);
 114                 return -ENODEV;
 115         }
 116
 117         domain = handle->perf_ops->device_domain_id(cpu_dev);
 118         if (domain < 0)
 119                 return domain;
 120
 121         /* Get the power cost of the performance domain. */
 122         Hz = *KHz * 1000;
 123         ret = handle->perf_ops->est_power_get(handle, domain, &Hz, power);
 124         if (ret)
 125                 return ret;
 126
 127         /* The EM framework specifies the frequency in KHz. */
 128         *KHz = Hz / 1000;
 129
 130         return 0;
 131 }
 132
 133 static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 134 {
 135         int ret, nr_opp;
 136         unsigned int latency;
 137         struct device *cpu_dev;
 138         struct scmi_data *priv;
 139         struct cpufreq_frequency_table *freq_table;
 140         struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
 141
 142         cpu_dev = get_cpu_device(policy->cpu);
 143         if (!cpu_dev) {
 144                 pr_err("failed to get cpu%d device\n", policy->cpu);
 145                 return -ENODEV;
 146         }
 147
 148         ret = handle->perf_ops->device_opps_add(handle, cpu_dev);
 149         if (ret) {
 150                 dev_warn(cpu_dev, "failed to add opps to the device\n");
 151                 return ret;
 152         }
 153
 154         ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus);
 155         if (ret) {
 156                 dev_warn(cpu_dev, "failed to get sharing cpumask\n");
 157                 return ret;
 158         }
 159
 160         ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus);
 161         if (ret) {
 162                 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
 163                         __func__, ret);
 164                 return ret;
 165         }
 166
 167         nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
 168         if (nr_opp <= 0) {
 169                 dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n");
 170                 ret = -EPROBE_DEFER;
 171                 goto out_free_opp;
 172         }
 173
 174         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 175         if (!priv) {
 176                 ret = -ENOMEM;
 177                 goto out_free_opp;
 178         }
 179
 180         ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
 181         if (ret) {
 182                 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
 183                 goto out_free_priv;
 184         }
 185
 186         priv->cpu_dev = cpu_dev;
 187         priv->domain_id = handle->perf_ops->device_domain_id(cpu_dev);
 188
 189         policy->driver_data = priv;
 190         policy->freq_table = freq_table;
 191
 192         /* SCMI allows DVFS request for any domain from any CPU */
 193         policy->dvfs_possible_from_any_cpu = true;
 194
 195         latency = handle->perf_ops->transition_latency_get(handle, cpu_dev);
 196         if (!latency)
 197                 latency = CPUFREQ_ETERNAL;
 198
 199         policy->cpuinfo.transition_latency = latency;
 200
 201         policy->fast_switch_possible = true;
 202
 203         em_register_perf_domain(policy->cpus, nr_opp, &em_cb);
 204
 205         return 0;
 206
 207 out_free_priv:
 208         kfree(priv);
 209 out_free_opp:
 210         dev_pm_opp_remove_all_dynamic(cpu_dev);
 211
 212         return ret;
 213 }
 214
 215 static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
 216 {
 217         struct scmi_data *priv = policy->driver_data;
 218
 219         dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
 220         dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
 221         kfree(priv);
 222
 223         return 0;
 224 }
 225
 226 static struct cpufreq_driver scmi_cpufreq_driver = {
 227         .name   = "scmi",
 228         .flags  = CPUFREQ_STICKY | CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
 229                   CPUFREQ_NEED_INITIAL_FREQ_CHECK |
 230                   CPUFREQ_IS_COOLING_DEV,
 231         .verify = cpufreq_generic_frequency_table_verify,
 232         .attr   = cpufreq_generic_attr,
 233         .target_index   = scmi_cpufreq_set_target,
 234         .fast_switch    = scmi_cpufreq_fast_switch,
 235         .get    = scmi_cpufreq_get_rate,
 236         .init   = scmi_cpufreq_init,
 237         .exit   = scmi_cpufreq_exit,
 238 };
 239
 240 static int scmi_cpufreq_probe(struct scmi_device *sdev)
 241 {
 242         int ret;
 243
 244         handle = sdev->handle;
 245
 246         if (!handle || !handle->perf_ops)
 247                 return -ENODEV;
 248
 249         ret = cpufreq_register_driver(&scmi_cpufreq_driver);
 250         if (ret) {
 251                 dev_err(&sdev->dev, "%s: registering cpufreq failed, err: %d\n",
 252                         __func__, ret);
 253         }
 254
 255         return ret;
 256 }
 257
 258 static void scmi_cpufreq_remove(struct scmi_device *sdev)
 259 {
 260         cpufreq_unregister_driver(&scmi_cpufreq_driver);
 261 }
 262
 263 static const struct scmi_device_id scmi_id_table[] = {
 264         { SCMI_PROTOCOL_PERF },
 265         { },
 266 };
 267 MODULE_DEVICE_TABLE(scmi, scmi_id_table);
 268
 269 static struct scmi_driver scmi_cpufreq_drv = {
 270         .name           = "scmi-cpufreq",
 271         .probe          = scmi_cpufreq_probe,
 272         .remove         = scmi_cpufreq_remove,
 273         .id_table       = scmi_id_table,
 274 };
 275 module_scmi_driver(scmi_cpufreq_drv);
 276
 277 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
 278 MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
 279 MODULE_LICENSE("GPL v2");