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