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