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