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) 2018-2021 ARM Ltd.
   6  * Sudeep Holla <sudeep.holla@arm.com>
   7  */
   8
   9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  10
  11 #include <linux/clk-provider.h>
  12 #include <linux/cpu.h>
  13 #include <linux/cpufreq.h>
  14 #include <linux/cpumask.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 };
  27
  28 static struct scmi_protocol_handle *ph;
  29 static const struct scmi_perf_proto_ops *perf_ops;
  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_data *priv = policy->driver_data;
  35         unsigned long rate;
  36         int ret;
  37
  38         ret = perf_ops->freq_get(ph, 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         struct scmi_data *priv = policy->driver_data;
  53         u64 freq = policy->freq_table[index].frequency;
  54
  55         return perf_ops->freq_set(ph, 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
  63         if (!perf_ops->freq_set(ph, priv->domain_id,
  64                                 target_freq * 1000, true))
  65                 return target_freq;
  66
  67         return 0;
  68 }
  69
  70 static int
  71 scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
  72 {
  73         int cpu, domain, tdomain;
  74         struct device *tcpu_dev;
  75
  76         domain = perf_ops->device_domain_id(cpu_dev);
  77         if (domain < 0)
  78                 return domain;
  79
  80         for_each_possible_cpu(cpu) {
  81                 if (cpu == cpu_dev->id)
  82                         continue;
  83
  84                 tcpu_dev = get_cpu_device(cpu);
  85                 if (!tcpu_dev)
  86                         continue;
  87
  88                 tdomain = perf_ops->device_domain_id(tcpu_dev);
  89                 if (tdomain == domain)
  90                         cpumask_set_cpu(cpu, cpumask);
  91         }
  92
  93         return 0;
  94 }
  95
  96 static int __maybe_unused
  97 scmi_get_cpu_power(unsigned long *power, unsigned long *KHz,
  98                    struct device *cpu_dev)
  99 {
 100         unsigned long Hz;
 101         int ret, domain;
 102
 103         domain = perf_ops->device_domain_id(cpu_dev);
 104         if (domain < 0)
 105                 return domain;
 106
 107         /* Get the power cost of the performance domain. */
 108         Hz = *KHz * 1000;
 109         ret = perf_ops->est_power_get(ph, domain, &Hz, power);
 110         if (ret)
 111                 return ret;
 112
 113         /* The EM framework specifies the frequency in KHz. */
 114         *KHz = Hz / 1000;
 115
 116         return 0;
 117 }
 118
 119 static int scmi_cpufreq_init(struct cpufreq_policy *policy)
 120 {
 121         int ret, nr_opp;
 122         unsigned int latency;
 123         struct device *cpu_dev;
 124         struct scmi_data *priv;
 125         struct cpufreq_frequency_table *freq_table;
 126         struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
 127         cpumask_var_t opp_shared_cpus;
 128         bool power_scale_mw;
 129
 130         cpu_dev = get_cpu_device(policy->cpu);
 131         if (!cpu_dev) {
 132                 pr_err("failed to get cpu%d device\n", policy->cpu);
 133                 return -ENODEV;
 134         }
 135
 136         if (!zalloc_cpumask_var(&opp_shared_cpus, GFP_KERNEL))
 137                 return -ENOMEM;
 138
 139         /* Obtain CPUs that share SCMI performance controls */
 140         ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus);
 141         if (ret) {
 142                 dev_warn(cpu_dev, "failed to get sharing cpumask\n");
 143                 goto out_free_cpumask;
 144         }
 145
 146         /*
 147          * Obtain CPUs that share performance levels.
 148          * The OPP 'sharing cpus' info may come from DT through an empty opp
 149          * table and opp-shared.
 150          */
 151         ret = dev_pm_opp_of_get_sharing_cpus(cpu_dev, opp_shared_cpus);
 152         if (ret || !cpumask_weight(opp_shared_cpus)) {
 153                 /*
 154                  * Either opp-table is not set or no opp-shared was found.
 155                  * Use the CPU mask from SCMI to designate CPUs sharing an OPP
 156                  * table.
 157                  */
 158                 cpumask_copy(opp_shared_cpus, policy->cpus);
 159         }
 160
 161          /*
 162           * A previous CPU may have marked OPPs as shared for a few CPUs, based on
 163           * what OPP core provided. If the current CPU is part of those few, then
 164           * there is no need to add OPPs again.
 165           */
 166         nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
 167         if (nr_opp <= 0) {
 168                 ret = perf_ops->device_opps_add(ph, cpu_dev);
 169                 if (ret) {
 170                         dev_warn(cpu_dev, "failed to add opps to the device\n");
 171                         goto out_free_cpumask;
 172                 }
 173
 174                 nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
 175                 if (nr_opp <= 0) {
 176                         dev_err(cpu_dev, "%s: No OPPs for this device: %d\n",
 177                                 __func__, nr_opp);
 178
 179                         ret = -ENODEV;
 180                         goto out_free_opp;
 181                 }
 182
 183                 ret = dev_pm_opp_set_sharing_cpus(cpu_dev, opp_shared_cpus);
 184                 if (ret) {
 185                         dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
 186                                 __func__, ret);
 187
 188                         goto out_free_opp;
 189                 }
 190
 191                 power_scale_mw = perf_ops->power_scale_mw_get(ph);
 192                 em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb,
 193                                             opp_shared_cpus, power_scale_mw);
 194         }
 195
 196         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 197         if (!priv) {
 198                 ret = -ENOMEM;
 199                 goto out_free_opp;
 200         }
 201
 202         ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
 203         if (ret) {
 204                 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
 205                 goto out_free_priv;
 206         }
 207
 208         priv->cpu_dev = cpu_dev;
 209         priv->domain_id = perf_ops->device_domain_id(cpu_dev);
 210
 211         policy->driver_data = priv;
 212         policy->freq_table = freq_table;
 213
 214         /* SCMI allows DVFS request for any domain from any CPU */
 215         policy->dvfs_possible_from_any_cpu = true;
 216
 217         latency = perf_ops->transition_latency_get(ph, cpu_dev);
 218         if (!latency)
 219                 latency = CPUFREQ_ETERNAL;
 220
 221         policy->cpuinfo.transition_latency = latency;
 222
 223         policy->fast_switch_possible =
 224                 perf_ops->fast_switch_possible(ph, cpu_dev);
 225
 226         free_cpumask_var(opp_shared_cpus);
 227         return 0;
 228
 229 out_free_priv:
 230         kfree(priv);
 231
 232 out_free_opp:
 233         dev_pm_opp_remove_all_dynamic(cpu_dev);
 234
 235 out_free_cpumask:
 236         free_cpumask_var(opp_shared_cpus);
 237
 238         return ret;
 239 }
 240
 241 static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
 242 {
 243         struct scmi_data *priv = policy->driver_data;
 244
 245         dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
 246         dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
 247         kfree(priv);
 248
 249         return 0;
 250 }
 251
 252 static struct cpufreq_driver scmi_cpufreq_driver = {
 253         .name   = "scmi",
 254         .flags  = CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
 255                   CPUFREQ_NEED_INITIAL_FREQ_CHECK |
 256                   CPUFREQ_IS_COOLING_DEV,
 257         .verify = cpufreq_generic_frequency_table_verify,
 258         .attr   = cpufreq_generic_attr,
 259         .target_index   = scmi_cpufreq_set_target,
 260         .fast_switch    = scmi_cpufreq_fast_switch,
 261         .get    = scmi_cpufreq_get_rate,
 262         .init   = scmi_cpufreq_init,
 263         .exit   = scmi_cpufreq_exit,
 264 };
 265
 266 static int scmi_cpufreq_probe(struct scmi_device *sdev)
 267 {
 268         int ret;
 269         struct device *dev = &sdev->dev;
 270         const struct scmi_handle *handle;
 271
 272         handle = sdev->handle;
 273
 274         if (!handle)
 275                 return -ENODEV;
 276
 277         perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
 278         if (IS_ERR(perf_ops))
 279                 return PTR_ERR(perf_ops);
 280
 281 #ifdef CONFIG_COMMON_CLK
 282         /* dummy clock provider as needed by OPP if clocks property is used */
 283         if (of_find_property(dev->of_node, "#clock-cells", NULL))
 284                 devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, NULL);
 285 #endif
 286
 287         ret = cpufreq_register_driver(&scmi_cpufreq_driver);
 288         if (ret) {
 289                 dev_err(dev, "%s: registering cpufreq failed, err: %d\n",
 290                         __func__, ret);
 291         }
 292
 293         return ret;
 294 }
 295
 296 static void scmi_cpufreq_remove(struct scmi_device *sdev)
 297 {
 298         cpufreq_unregister_driver(&scmi_cpufreq_driver);
 299 }
 300
 301 static const struct scmi_device_id scmi_id_table[] = {
 302         { SCMI_PROTOCOL_PERF, "cpufreq" },
 303         { },
 304 };
 305 MODULE_DEVICE_TABLE(scmi, scmi_id_table);
 306
 307 static struct scmi_driver scmi_cpufreq_drv = {
 308         .name           = "scmi-cpufreq",
 309         .probe          = scmi_cpufreq_probe,
 310         .remove         = scmi_cpufreq_remove,
 311         .id_table       = scmi_id_table,
 312 };
 313 module_scmi_driver(scmi_cpufreq_drv);
 314
 315 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
 316 MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
 317 MODULE_LICENSE("GPL v2");