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,
 107                    struct device *cpu_dev)
 108 {
 109         unsigned long Hz;
 110         int ret, domain;
 111
 112         domain = handle->perf_ops->device_domain_id(cpu_dev);
 113         if (domain < 0)
 114                 return domain;
 115
 116         /* Get the power cost of the performance domain. */
 117         Hz = *KHz * 1000;
 118         ret = handle->perf_ops->est_power_get(handle, domain, &Hz, power);
 119         if (ret)
 120                 return ret;
 121
 122         /* The EM framework specifies the frequency in KHz. */
 123         *KHz = Hz / 1000;
 124
 125         return 0;
 126 }
 127
 128 static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 129 {
 130         int ret, nr_opp;
 131         unsigned int latency;
 132         struct device *cpu_dev;
 133         struct scmi_data *priv;
 134         struct cpufreq_frequency_table *freq_table;
 135         struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
 136
 137         cpu_dev = get_cpu_device(policy->cpu);
 138         if (!cpu_dev) {
 139                 pr_err("failed to get cpu%d device\n", policy->cpu);
 140                 return -ENODEV;
 141         }
 142
 143         ret = handle->perf_ops->device_opps_add(handle, cpu_dev);
 144         if (ret) {
 145                 dev_warn(cpu_dev, "failed to add opps to the device\n");
 146                 return ret;
 147         }
 148
 149         ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus);
 150         if (ret) {
 151                 dev_warn(cpu_dev, "failed to get sharing cpumask\n");
 152                 return ret;
 153         }
 154
 155         ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus);
 156         if (ret) {
 157                 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
 158                         __func__, ret);
 159                 return ret;
 160         }
 161
 162         nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
 163         if (nr_opp <= 0) {
 164                 dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n");
 165                 ret = -EPROBE_DEFER;
 166                 goto out_free_opp;
 167         }
 168
 169         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 170         if (!priv) {
 171                 ret = -ENOMEM;
 172                 goto out_free_opp;
 173         }
 174
 175         ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
 176         if (ret) {
 177                 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
 178                 goto out_free_priv;
 179         }
 180
 181         priv->cpu_dev = cpu_dev;
 182         priv->domain_id = handle->perf_ops->device_domain_id(cpu_dev);
 183
 184         policy->driver_data = priv;
 185         policy->freq_table = freq_table;
 186
 187         /* SCMI allows DVFS request for any domain from any CPU */
 188         policy->dvfs_possible_from_any_cpu = true;
 189
 190         latency = handle->perf_ops->transition_latency_get(handle, cpu_dev);
 191         if (!latency)
 192                 latency = CPUFREQ_ETERNAL;
 193
 194         policy->cpuinfo.transition_latency = latency;
 195
 196         policy->fast_switch_possible =
 197                 handle->perf_ops->fast_switch_possible(handle, cpu_dev);
 198
 199         em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb, policy->cpus);
 200
 201         return 0;
 202
 203 out_free_priv:
 204         kfree(priv);
 205 out_free_opp:
 206         dev_pm_opp_remove_all_dynamic(cpu_dev);
 207
 208         return ret;
 209 }
 210
 211 static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
 212 {
 213         struct scmi_data *priv = policy->driver_data;
 214
 215         dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
 216         dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
 217         kfree(priv);
 218
 219         return 0;
 220 }
 221
 222 static struct cpufreq_driver scmi_cpufreq_driver = {
 223         .name   = "scmi",
 224         .flags  = CPUFREQ_STICKY | CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
 225                   CPUFREQ_NEED_INITIAL_FREQ_CHECK |
 226                   CPUFREQ_IS_COOLING_DEV,
 227         .verify = cpufreq_generic_frequency_table_verify,
 228         .attr   = cpufreq_generic_attr,
 229         .target_index   = scmi_cpufreq_set_target,
 230         .fast_switch    = scmi_cpufreq_fast_switch,
 231         .get    = scmi_cpufreq_get_rate,
 232         .init   = scmi_cpufreq_init,
 233         .exit   = scmi_cpufreq_exit,
 234 };
 235
 236 static int scmi_cpufreq_probe(struct scmi_device *sdev)
 237 {
 238         int ret;
 239
 240         handle = sdev->handle;
 241
 242         if (!handle || !handle->perf_ops)
 243                 return -ENODEV;
 244
 245         ret = cpufreq_register_driver(&scmi_cpufreq_driver);
 246         if (ret) {
 247                 dev_err(&sdev->dev, "%s: registering cpufreq failed, err: %d\n",
 248                         __func__, ret);
 249         }
 250
 251         return ret;
 252 }
 253
 254 static void scmi_cpufreq_remove(struct scmi_device *sdev)
 255 {
 256         cpufreq_unregister_driver(&scmi_cpufreq_driver);
 257 }
 258
 259 static const struct scmi_device_id scmi_id_table[] = {
 260         { SCMI_PROTOCOL_PERF, "cpufreq" },
 261         { },
 262 };
 263 MODULE_DEVICE_TABLE(scmi, scmi_id_table);
 264
 265 static struct scmi_driver scmi_cpufreq_drv = {
 266         .name           = "scmi-cpufreq",
 267         .probe          = scmi_cpufreq_probe,
 268         .remove         = scmi_cpufreq_remove,
 269         .id_table       = scmi_id_table,
 270 };
 271 module_scmi_driver(scmi_cpufreq_drv);
 272
 273 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
 274 MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
 275 MODULE_LICENSE("GPL v2");