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