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 #include <linux/units.h> 23 24 struct scmi_data { 25 int domain_id; 26 int nr_opp; 27 struct device *cpu_dev; 28 cpumask_var_t opp_shared_cpus; 29 }; 30 31 static struct scmi_protocol_handle *ph; 32 static const struct scmi_perf_proto_ops *perf_ops; 33 34 static unsigned int scmi_cpufreq_get_rate(unsigned int cpu) 35 { 36 struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu); 37 struct scmi_data *priv = policy->driver_data; 38 unsigned long rate; 39 int ret; 40 41 ret = perf_ops->freq_get(ph, priv->domain_id, &rate, false); 42 if (ret) 43 return 0; 44 return rate / 1000; 45 } 46 47 /* 48 * perf_ops->freq_set is not a synchronous, the actual OPP change will 49 * happen asynchronously and can get notified if the events are 50 * subscribed for by the SCMI firmware 51 */ 52 static int 53 scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index) 54 { 55 struct scmi_data *priv = policy->driver_data; 56 u64 freq = policy->freq_table[index].frequency; 57 58 return perf_ops->freq_set(ph, priv->domain_id, freq * 1000, false); 59 } 60 61 static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy, 62 unsigned int target_freq) 63 { 64 struct scmi_data *priv = policy->driver_data; 65 unsigned long freq = target_freq; 66 67 if (!perf_ops->freq_set(ph, priv->domain_id, freq * 1000, true)) 68 return target_freq; 69 70 return 0; 71 } 72 73 static int 74 scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask) 75 { 76 int cpu, domain, tdomain; 77 struct device *tcpu_dev; 78 79 domain = perf_ops->device_domain_id(cpu_dev); 80 if (domain < 0) 81 return domain; 82 83 for_each_possible_cpu(cpu) { 84 if (cpu == cpu_dev->id) 85 continue; 86 87 tcpu_dev = get_cpu_device(cpu); 88 if (!tcpu_dev) 89 continue; 90 91 tdomain = perf_ops->device_domain_id(tcpu_dev); 92 if (tdomain == domain) 93 cpumask_set_cpu(cpu, cpumask); 94 } 95 96 return 0; 97 } 98 99 static int __maybe_unused 100 scmi_get_cpu_power(struct device *cpu_dev, unsigned long *power, 101 unsigned long *KHz) 102 { 103 enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph); 104 unsigned long Hz; 105 int ret, domain; 106 107 domain = perf_ops->device_domain_id(cpu_dev); 108 if (domain < 0) 109 return domain; 110 111 /* Get the power cost of the performance domain. */ 112 Hz = *KHz * 1000; 113 ret = perf_ops->est_power_get(ph, domain, &Hz, power); 114 if (ret) 115 return ret; 116 117 /* Convert the power to uW if it is mW (ignore bogoW) */ 118 if (power_scale == SCMI_POWER_MILLIWATTS) 119 *power *= MICROWATT_PER_MILLIWATT; 120 121 /* The EM framework specifies the frequency in KHz. */ 122 *KHz = Hz / 1000; 123 124 return 0; 125 } 126 127 static int scmi_cpufreq_init(struct cpufreq_policy *policy) 128 { 129 int ret, nr_opp; 130 unsigned int latency; 131 struct device *cpu_dev; 132 struct scmi_data *priv; 133 struct cpufreq_frequency_table *freq_table; 134 135 cpu_dev = get_cpu_device(policy->cpu); 136 if (!cpu_dev) { 137 pr_err("failed to get cpu%d device\n", policy->cpu); 138 return -ENODEV; 139 } 140 141 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 142 if (!priv) 143 return -ENOMEM; 144 145 if (!zalloc_cpumask_var(&priv->opp_shared_cpus, GFP_KERNEL)) { 146 ret = -ENOMEM; 147 goto out_free_priv; 148 } 149 150 /* Obtain CPUs that share SCMI performance controls */ 151 ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus); 152 if (ret) { 153 dev_warn(cpu_dev, "failed to get sharing cpumask\n"); 154 goto out_free_cpumask; 155 } 156 157 /* 158 * Obtain CPUs that share performance levels. 159 * The OPP 'sharing cpus' info may come from DT through an empty opp 160 * table and opp-shared. 161 */ 162 ret = dev_pm_opp_of_get_sharing_cpus(cpu_dev, priv->opp_shared_cpus); 163 if (ret || cpumask_empty(priv->opp_shared_cpus)) { 164 /* 165 * Either opp-table is not set or no opp-shared was found. 166 * Use the CPU mask from SCMI to designate CPUs sharing an OPP 167 * table. 168 */ 169 cpumask_copy(priv->opp_shared_cpus, policy->cpus); 170 } 171 172 /* 173 * A previous CPU may have marked OPPs as shared for a few CPUs, based on 174 * what OPP core provided. If the current CPU is part of those few, then 175 * there is no need to add OPPs again. 176 */ 177 nr_opp = dev_pm_opp_get_opp_count(cpu_dev); 178 if (nr_opp <= 0) { 179 ret = perf_ops->device_opps_add(ph, cpu_dev); 180 if (ret) { 181 dev_warn(cpu_dev, "failed to add opps to the device\n"); 182 goto out_free_cpumask; 183 } 184 185 nr_opp = dev_pm_opp_get_opp_count(cpu_dev); 186 if (nr_opp <= 0) { 187 dev_err(cpu_dev, "%s: No OPPs for this device: %d\n", 188 __func__, nr_opp); 189 190 ret = -ENODEV; 191 goto out_free_opp; 192 } 193 194 ret = dev_pm_opp_set_sharing_cpus(cpu_dev, priv->opp_shared_cpus); 195 if (ret) { 196 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n", 197 __func__, ret); 198 199 goto out_free_opp; 200 } 201 202 priv->nr_opp = nr_opp; 203 } 204 205 ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table); 206 if (ret) { 207 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret); 208 goto out_free_opp; 209 } 210 211 priv->cpu_dev = cpu_dev; 212 priv->domain_id = perf_ops->device_domain_id(cpu_dev); 213 214 policy->driver_data = priv; 215 policy->freq_table = freq_table; 216 217 /* SCMI allows DVFS request for any domain from any CPU */ 218 policy->dvfs_possible_from_any_cpu = true; 219 220 latency = perf_ops->transition_latency_get(ph, cpu_dev); 221 if (!latency) 222 latency = CPUFREQ_ETERNAL; 223 224 policy->cpuinfo.transition_latency = latency; 225 226 policy->fast_switch_possible = 227 perf_ops->fast_switch_possible(ph, cpu_dev); 228 229 return 0; 230 231 out_free_opp: 232 dev_pm_opp_remove_all_dynamic(cpu_dev); 233 234 out_free_cpumask: 235 free_cpumask_var(priv->opp_shared_cpus); 236 237 out_free_priv: 238 kfree(priv); 239 240 return ret; 241 } 242 243 static int scmi_cpufreq_exit(struct cpufreq_policy *policy) 244 { 245 struct scmi_data *priv = policy->driver_data; 246 247 dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table); 248 dev_pm_opp_remove_all_dynamic(priv->cpu_dev); 249 free_cpumask_var(priv->opp_shared_cpus); 250 kfree(priv); 251 252 return 0; 253 } 254 255 static void scmi_cpufreq_register_em(struct cpufreq_policy *policy) 256 { 257 struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power); 258 enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph); 259 struct scmi_data *priv = policy->driver_data; 260 bool em_power_scale = false; 261 262 /* 263 * This callback will be called for each policy, but we don't need to 264 * register with EM every time. Despite not being part of the same 265 * policy, some CPUs may still share their perf-domains, and a CPU from 266 * another policy may already have registered with EM on behalf of CPUs 267 * of this policy. 268 */ 269 if (!priv->nr_opp) 270 return; 271 272 if (power_scale == SCMI_POWER_MILLIWATTS 273 || power_scale == SCMI_POWER_MICROWATTS) 274 em_power_scale = true; 275 276 em_dev_register_perf_domain(get_cpu_device(policy->cpu), priv->nr_opp, 277 &em_cb, priv->opp_shared_cpus, 278 em_power_scale); 279 } 280 281 static struct cpufreq_driver scmi_cpufreq_driver = { 282 .name = "scmi", 283 .flags = CPUFREQ_HAVE_GOVERNOR_PER_POLICY | 284 CPUFREQ_NEED_INITIAL_FREQ_CHECK | 285 CPUFREQ_IS_COOLING_DEV, 286 .verify = cpufreq_generic_frequency_table_verify, 287 .attr = cpufreq_generic_attr, 288 .target_index = scmi_cpufreq_set_target, 289 .fast_switch = scmi_cpufreq_fast_switch, 290 .get = scmi_cpufreq_get_rate, 291 .init = scmi_cpufreq_init, 292 .exit = scmi_cpufreq_exit, 293 .register_em = scmi_cpufreq_register_em, 294 }; 295 296 static int scmi_cpufreq_probe(struct scmi_device *sdev) 297 { 298 int ret; 299 struct device *dev = &sdev->dev; 300 const struct scmi_handle *handle; 301 302 handle = sdev->handle; 303 304 if (!handle) 305 return -ENODEV; 306 307 perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph); 308 if (IS_ERR(perf_ops)) 309 return PTR_ERR(perf_ops); 310 311 #ifdef CONFIG_COMMON_CLK 312 /* dummy clock provider as needed by OPP if clocks property is used */ 313 if (of_property_present(dev->of_node, "#clock-cells")) { 314 ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, NULL); 315 if (ret) 316 return dev_err_probe(dev, ret, "%s: registering clock provider failed\n", __func__); 317 } 318 #endif 319 320 ret = cpufreq_register_driver(&scmi_cpufreq_driver); 321 if (ret) { 322 dev_err(dev, "%s: registering cpufreq failed, err: %d\n", 323 __func__, ret); 324 } 325 326 return ret; 327 } 328 329 static void scmi_cpufreq_remove(struct scmi_device *sdev) 330 { 331 cpufreq_unregister_driver(&scmi_cpufreq_driver); 332 } 333 334 static const struct scmi_device_id scmi_id_table[] = { 335 { SCMI_PROTOCOL_PERF, "cpufreq" }, 336 { }, 337 }; 338 MODULE_DEVICE_TABLE(scmi, scmi_id_table); 339 340 static struct scmi_driver scmi_cpufreq_drv = { 341 .name = "scmi-cpufreq", 342 .probe = scmi_cpufreq_probe, 343 .remove = scmi_cpufreq_remove, 344 .id_table = scmi_id_table, 345 }; 346 module_scmi_driver(scmi_cpufreq_drv); 347 348 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>"); 349 MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver"); 350 MODULE_LICENSE("GPL v2"); 351