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