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