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/cpu.h> 12 #include <linux/cpufreq.h> 13 #include <linux/cpumask.h> 14 #include <linux/energy_model.h> 15 #include <linux/export.h> 16 #include <linux/module.h> 17 #include <linux/pm_opp.h> 18 #include <linux/slab.h> 19 #include <linux/scmi_protocol.h> 20 #include <linux/types.h> 21 22 struct scmi_data { 23 int domain_id; 24 struct device *cpu_dev; 25 }; 26 27 static const struct scmi_handle *handle; 28 29 static unsigned int scmi_cpufreq_get_rate(unsigned int cpu) 30 { 31 struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu); 32 struct scmi_perf_ops *perf_ops = handle->perf_ops; 33 struct scmi_data *priv = policy->driver_data; 34 unsigned long rate; 35 int ret; 36 37 ret = perf_ops->freq_get(handle, priv->domain_id, &rate, false); 38 if (ret) 39 return 0; 40 return rate / 1000; 41 } 42 43 /* 44 * perf_ops->freq_set is not a synchronous, the actual OPP change will 45 * happen asynchronously and can get notified if the events are 46 * subscribed for by the SCMI firmware 47 */ 48 static int 49 scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index) 50 { 51 int ret; 52 struct scmi_data *priv = policy->driver_data; 53 struct scmi_perf_ops *perf_ops = handle->perf_ops; 54 u64 freq = policy->freq_table[index].frequency; 55 56 ret = perf_ops->freq_set(handle, priv->domain_id, freq * 1000, false); 57 if (!ret) 58 arch_set_freq_scale(policy->related_cpus, freq, 59 policy->cpuinfo.max_freq); 60 return ret; 61 } 62 63 static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy, 64 unsigned int target_freq) 65 { 66 struct scmi_data *priv = policy->driver_data; 67 struct scmi_perf_ops *perf_ops = handle->perf_ops; 68 69 if (!perf_ops->freq_set(handle, priv->domain_id, 70 target_freq * 1000, true)) { 71 arch_set_freq_scale(policy->related_cpus, target_freq, 72 policy->cpuinfo.max_freq); 73 return target_freq; 74 } 75 76 return 0; 77 } 78 79 static int 80 scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask) 81 { 82 int cpu, domain, tdomain; 83 struct device *tcpu_dev; 84 85 domain = handle->perf_ops->device_domain_id(cpu_dev); 86 if (domain < 0) 87 return domain; 88 89 for_each_possible_cpu(cpu) { 90 if (cpu == cpu_dev->id) 91 continue; 92 93 tcpu_dev = get_cpu_device(cpu); 94 if (!tcpu_dev) 95 continue; 96 97 tdomain = handle->perf_ops->device_domain_id(tcpu_dev); 98 if (tdomain == domain) 99 cpumask_set_cpu(cpu, cpumask); 100 } 101 102 return 0; 103 } 104 105 static int __maybe_unused 106 scmi_get_cpu_power(unsigned long *power, unsigned long *KHz, int cpu) 107 { 108 struct device *cpu_dev = get_cpu_device(cpu); 109 unsigned long Hz; 110 int ret, domain; 111 112 if (!cpu_dev) { 113 pr_err("failed to get cpu%d device\n", cpu); 114 return -ENODEV; 115 } 116 117 domain = handle->perf_ops->device_domain_id(cpu_dev); 118 if (domain < 0) 119 return domain; 120 121 /* Get the power cost of the performance domain. */ 122 Hz = *KHz * 1000; 123 ret = handle->perf_ops->est_power_get(handle, domain, &Hz, power); 124 if (ret) 125 return ret; 126 127 /* The EM framework specifies the frequency in KHz. */ 128 *KHz = Hz / 1000; 129 130 return 0; 131 } 132 133 static int scmi_cpufreq_init(struct cpufreq_policy *policy) 134 { 135 int ret, nr_opp; 136 unsigned int latency; 137 struct device *cpu_dev; 138 struct scmi_data *priv; 139 struct cpufreq_frequency_table *freq_table; 140 struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power); 141 142 cpu_dev = get_cpu_device(policy->cpu); 143 if (!cpu_dev) { 144 pr_err("failed to get cpu%d device\n", policy->cpu); 145 return -ENODEV; 146 } 147 148 ret = handle->perf_ops->device_opps_add(handle, cpu_dev); 149 if (ret) { 150 dev_warn(cpu_dev, "failed to add opps to the device\n"); 151 return ret; 152 } 153 154 ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus); 155 if (ret) { 156 dev_warn(cpu_dev, "failed to get sharing cpumask\n"); 157 return ret; 158 } 159 160 ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus); 161 if (ret) { 162 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n", 163 __func__, ret); 164 return ret; 165 } 166 167 nr_opp = dev_pm_opp_get_opp_count(cpu_dev); 168 if (nr_opp <= 0) { 169 dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n"); 170 ret = -EPROBE_DEFER; 171 goto out_free_opp; 172 } 173 174 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 175 if (!priv) { 176 ret = -ENOMEM; 177 goto out_free_opp; 178 } 179 180 ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table); 181 if (ret) { 182 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret); 183 goto out_free_priv; 184 } 185 186 priv->cpu_dev = cpu_dev; 187 priv->domain_id = handle->perf_ops->device_domain_id(cpu_dev); 188 189 policy->driver_data = priv; 190 policy->freq_table = freq_table; 191 192 /* SCMI allows DVFS request for any domain from any CPU */ 193 policy->dvfs_possible_from_any_cpu = true; 194 195 latency = handle->perf_ops->transition_latency_get(handle, cpu_dev); 196 if (!latency) 197 latency = CPUFREQ_ETERNAL; 198 199 policy->cpuinfo.transition_latency = latency; 200 201 policy->fast_switch_possible = true; 202 203 em_register_perf_domain(policy->cpus, nr_opp, &em_cb); 204 205 return 0; 206 207 out_free_priv: 208 kfree(priv); 209 out_free_opp: 210 dev_pm_opp_remove_all_dynamic(cpu_dev); 211 212 return ret; 213 } 214 215 static int scmi_cpufreq_exit(struct cpufreq_policy *policy) 216 { 217 struct scmi_data *priv = policy->driver_data; 218 219 dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table); 220 dev_pm_opp_remove_all_dynamic(priv->cpu_dev); 221 kfree(priv); 222 223 return 0; 224 } 225 226 static struct cpufreq_driver scmi_cpufreq_driver = { 227 .name = "scmi", 228 .flags = CPUFREQ_STICKY | CPUFREQ_HAVE_GOVERNOR_PER_POLICY | 229 CPUFREQ_NEED_INITIAL_FREQ_CHECK | 230 CPUFREQ_IS_COOLING_DEV, 231 .verify = cpufreq_generic_frequency_table_verify, 232 .attr = cpufreq_generic_attr, 233 .target_index = scmi_cpufreq_set_target, 234 .fast_switch = scmi_cpufreq_fast_switch, 235 .get = scmi_cpufreq_get_rate, 236 .init = scmi_cpufreq_init, 237 .exit = scmi_cpufreq_exit, 238 }; 239 240 static int scmi_cpufreq_probe(struct scmi_device *sdev) 241 { 242 int ret; 243 244 handle = sdev->handle; 245 246 if (!handle || !handle->perf_ops) 247 return -ENODEV; 248 249 ret = cpufreq_register_driver(&scmi_cpufreq_driver); 250 if (ret) { 251 dev_err(&sdev->dev, "%s: registering cpufreq failed, err: %d\n", 252 __func__, ret); 253 } 254 255 return ret; 256 } 257 258 static void scmi_cpufreq_remove(struct scmi_device *sdev) 259 { 260 cpufreq_unregister_driver(&scmi_cpufreq_driver); 261 } 262 263 static const struct scmi_device_id scmi_id_table[] = { 264 { SCMI_PROTOCOL_PERF }, 265 { }, 266 }; 267 MODULE_DEVICE_TABLE(scmi, scmi_id_table); 268 269 static struct scmi_driver scmi_cpufreq_drv = { 270 .name = "scmi-cpufreq", 271 .probe = scmi_cpufreq_probe, 272 .remove = scmi_cpufreq_remove, 273 .id_table = scmi_id_table, 274 }; 275 module_scmi_driver(scmi_cpufreq_drv); 276 277 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>"); 278 MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver"); 279 MODULE_LICENSE("GPL v2"); 280