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 66 if (!perf_ops->freq_set(ph, priv->domain_id, 67 target_freq * 1000, true)) 68 return target_freq; 69 70 return 0; 71 } 72 73 static int scmi_cpu_domain_id(struct device *cpu_dev) 74 { 75 struct device_node *np = cpu_dev->of_node; 76 struct of_phandle_args domain_id; 77 int index; 78 79 if (of_parse_phandle_with_args(np, "clocks", "#clock-cells", 0, 80 &domain_id)) { 81 /* Find the corresponding index for power-domain "perf". */ 82 index = of_property_match_string(np, "power-domain-names", 83 "perf"); 84 if (index < 0) 85 return -EINVAL; 86 87 if (of_parse_phandle_with_args(np, "power-domains", 88 "#power-domain-cells", index, 89 &domain_id)) 90 return -EINVAL; 91 } 92 93 return domain_id.args[0]; 94 } 95 96 static int 97 scmi_get_sharing_cpus(struct device *cpu_dev, int domain, 98 struct cpumask *cpumask) 99 { 100 int cpu, tdomain; 101 struct device *tcpu_dev; 102 103 for_each_possible_cpu(cpu) { 104 if (cpu == cpu_dev->id) 105 continue; 106 107 tcpu_dev = get_cpu_device(cpu); 108 if (!tcpu_dev) 109 continue; 110 111 tdomain = scmi_cpu_domain_id(tcpu_dev); 112 if (tdomain == domain) 113 cpumask_set_cpu(cpu, cpumask); 114 } 115 116 return 0; 117 } 118 119 static int __maybe_unused 120 scmi_get_cpu_power(struct device *cpu_dev, unsigned long *power, 121 unsigned long *KHz) 122 { 123 enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph); 124 unsigned long Hz; 125 int ret, domain; 126 127 domain = scmi_cpu_domain_id(cpu_dev); 128 if (domain < 0) 129 return domain; 130 131 /* Get the power cost of the performance domain. */ 132 Hz = *KHz * 1000; 133 ret = perf_ops->est_power_get(ph, domain, &Hz, power); 134 if (ret) 135 return ret; 136 137 /* Convert the power to uW if it is mW (ignore bogoW) */ 138 if (power_scale == SCMI_POWER_MILLIWATTS) 139 *power *= MICROWATT_PER_MILLIWATT; 140 141 /* The EM framework specifies the frequency in KHz. */ 142 *KHz = Hz / 1000; 143 144 return 0; 145 } 146 147 static int 148 scmi_get_rate_limit(u32 domain, bool has_fast_switch) 149 { 150 int ret, rate_limit; 151 152 if (has_fast_switch) { 153 /* 154 * Fast channels are used whenever available, 155 * so use their rate_limit value if populated. 156 */ 157 ret = perf_ops->fast_switch_rate_limit(ph, domain, 158 &rate_limit); 159 if (!ret && rate_limit) 160 return rate_limit; 161 } 162 163 ret = perf_ops->rate_limit_get(ph, domain, &rate_limit); 164 if (ret) 165 return 0; 166 167 return rate_limit; 168 } 169 170 static int scmi_cpufreq_init(struct cpufreq_policy *policy) 171 { 172 int ret, nr_opp, domain; 173 unsigned int latency; 174 struct device *cpu_dev; 175 struct scmi_data *priv; 176 struct cpufreq_frequency_table *freq_table; 177 178 cpu_dev = get_cpu_device(policy->cpu); 179 if (!cpu_dev) { 180 pr_err("failed to get cpu%d device\n", policy->cpu); 181 return -ENODEV; 182 } 183 184 domain = scmi_cpu_domain_id(cpu_dev); 185 if (domain < 0) 186 return domain; 187 188 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 189 if (!priv) 190 return -ENOMEM; 191 192 if (!zalloc_cpumask_var(&priv->opp_shared_cpus, GFP_KERNEL)) { 193 ret = -ENOMEM; 194 goto out_free_priv; 195 } 196 197 /* Obtain CPUs that share SCMI performance controls */ 198 ret = scmi_get_sharing_cpus(cpu_dev, domain, policy->cpus); 199 if (ret) { 200 dev_warn(cpu_dev, "failed to get sharing cpumask\n"); 201 goto out_free_cpumask; 202 } 203 204 /* 205 * Obtain CPUs that share performance levels. 206 * The OPP 'sharing cpus' info may come from DT through an empty opp 207 * table and opp-shared. 208 */ 209 ret = dev_pm_opp_of_get_sharing_cpus(cpu_dev, priv->opp_shared_cpus); 210 if (ret || cpumask_empty(priv->opp_shared_cpus)) { 211 /* 212 * Either opp-table is not set or no opp-shared was found. 213 * Use the CPU mask from SCMI to designate CPUs sharing an OPP 214 * table. 215 */ 216 cpumask_copy(priv->opp_shared_cpus, policy->cpus); 217 } 218 219 /* 220 * A previous CPU may have marked OPPs as shared for a few CPUs, based on 221 * what OPP core provided. If the current CPU is part of those few, then 222 * there is no need to add OPPs again. 223 */ 224 nr_opp = dev_pm_opp_get_opp_count(cpu_dev); 225 if (nr_opp <= 0) { 226 ret = perf_ops->device_opps_add(ph, cpu_dev, domain); 227 if (ret) { 228 dev_warn(cpu_dev, "failed to add opps to the device\n"); 229 goto out_free_cpumask; 230 } 231 232 nr_opp = dev_pm_opp_get_opp_count(cpu_dev); 233 if (nr_opp <= 0) { 234 dev_err(cpu_dev, "%s: No OPPs for this device: %d\n", 235 __func__, nr_opp); 236 237 ret = -ENODEV; 238 goto out_free_opp; 239 } 240 241 ret = dev_pm_opp_set_sharing_cpus(cpu_dev, priv->opp_shared_cpus); 242 if (ret) { 243 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n", 244 __func__, ret); 245 246 goto out_free_opp; 247 } 248 249 priv->nr_opp = nr_opp; 250 } 251 252 ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table); 253 if (ret) { 254 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret); 255 goto out_free_opp; 256 } 257 258 priv->cpu_dev = cpu_dev; 259 priv->domain_id = domain; 260 261 policy->driver_data = priv; 262 policy->freq_table = freq_table; 263 264 /* SCMI allows DVFS request for any domain from any CPU */ 265 policy->dvfs_possible_from_any_cpu = true; 266 267 latency = perf_ops->transition_latency_get(ph, domain); 268 if (!latency) 269 latency = CPUFREQ_ETERNAL; 270 271 policy->cpuinfo.transition_latency = latency; 272 273 policy->fast_switch_possible = 274 perf_ops->fast_switch_possible(ph, domain); 275 276 policy->transition_delay_us = 277 scmi_get_rate_limit(domain, policy->fast_switch_possible); 278 279 return 0; 280 281 out_free_opp: 282 dev_pm_opp_remove_all_dynamic(cpu_dev); 283 284 out_free_cpumask: 285 free_cpumask_var(priv->opp_shared_cpus); 286 287 out_free_priv: 288 kfree(priv); 289 290 return ret; 291 } 292 293 static int scmi_cpufreq_exit(struct cpufreq_policy *policy) 294 { 295 struct scmi_data *priv = policy->driver_data; 296 297 dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table); 298 dev_pm_opp_remove_all_dynamic(priv->cpu_dev); 299 free_cpumask_var(priv->opp_shared_cpus); 300 kfree(priv); 301 302 return 0; 303 } 304 305 static void scmi_cpufreq_register_em(struct cpufreq_policy *policy) 306 { 307 struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power); 308 enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph); 309 struct scmi_data *priv = policy->driver_data; 310 bool em_power_scale = false; 311 312 /* 313 * This callback will be called for each policy, but we don't need to 314 * register with EM every time. Despite not being part of the same 315 * policy, some CPUs may still share their perf-domains, and a CPU from 316 * another policy may already have registered with EM on behalf of CPUs 317 * of this policy. 318 */ 319 if (!priv->nr_opp) 320 return; 321 322 if (power_scale == SCMI_POWER_MILLIWATTS 323 || power_scale == SCMI_POWER_MICROWATTS) 324 em_power_scale = true; 325 326 em_dev_register_perf_domain(get_cpu_device(policy->cpu), priv->nr_opp, 327 &em_cb, priv->opp_shared_cpus, 328 em_power_scale); 329 } 330 331 static struct cpufreq_driver scmi_cpufreq_driver = { 332 .name = "scmi", 333 .flags = CPUFREQ_HAVE_GOVERNOR_PER_POLICY | 334 CPUFREQ_NEED_INITIAL_FREQ_CHECK | 335 CPUFREQ_IS_COOLING_DEV, 336 .verify = cpufreq_generic_frequency_table_verify, 337 .attr = cpufreq_generic_attr, 338 .target_index = scmi_cpufreq_set_target, 339 .fast_switch = scmi_cpufreq_fast_switch, 340 .get = scmi_cpufreq_get_rate, 341 .init = scmi_cpufreq_init, 342 .exit = scmi_cpufreq_exit, 343 .register_em = scmi_cpufreq_register_em, 344 }; 345 346 static int scmi_cpufreq_probe(struct scmi_device *sdev) 347 { 348 int ret; 349 struct device *dev = &sdev->dev; 350 const struct scmi_handle *handle; 351 352 handle = sdev->handle; 353 354 if (!handle) 355 return -ENODEV; 356 357 perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph); 358 if (IS_ERR(perf_ops)) 359 return PTR_ERR(perf_ops); 360 361 #ifdef CONFIG_COMMON_CLK 362 /* dummy clock provider as needed by OPP if clocks property is used */ 363 if (of_property_present(dev->of_node, "#clock-cells")) { 364 ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, NULL); 365 if (ret) 366 return dev_err_probe(dev, ret, "%s: registering clock provider failed\n", __func__); 367 } 368 #endif 369 370 ret = cpufreq_register_driver(&scmi_cpufreq_driver); 371 if (ret) { 372 dev_err(dev, "%s: registering cpufreq failed, err: %d\n", 373 __func__, ret); 374 } 375 376 return ret; 377 } 378 379 static void scmi_cpufreq_remove(struct scmi_device *sdev) 380 { 381 cpufreq_unregister_driver(&scmi_cpufreq_driver); 382 } 383 384 static const struct scmi_device_id scmi_id_table[] = { 385 { SCMI_PROTOCOL_PERF, "cpufreq" }, 386 { }, 387 }; 388 MODULE_DEVICE_TABLE(scmi, scmi_id_table); 389 390 static struct scmi_driver scmi_cpufreq_drv = { 391 .name = "scmi-cpufreq", 392 .probe = scmi_cpufreq_probe, 393 .remove = scmi_cpufreq_remove, 394 .id_table = scmi_id_table, 395 }; 396 module_scmi_driver(scmi_cpufreq_drv); 397 398 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>"); 399 MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver"); 400 MODULE_LICENSE("GPL v2"); 401