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 const 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 struct scmi_data *priv = policy->driver_data; 52 const struct scmi_perf_ops *perf_ops = handle->perf_ops; 53 u64 freq = policy->freq_table[index].frequency; 54 55 return perf_ops->freq_set(handle, 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 const struct scmi_perf_ops *perf_ops = handle->perf_ops; 63 64 if (!perf_ops->freq_set(handle, priv->domain_id, 65 target_freq * 1000, true)) 66 return target_freq; 67 68 return 0; 69 } 70 71 static int 72 scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask) 73 { 74 int cpu, domain, tdomain; 75 struct device *tcpu_dev; 76 77 domain = handle->perf_ops->device_domain_id(cpu_dev); 78 if (domain < 0) 79 return domain; 80 81 for_each_possible_cpu(cpu) { 82 if (cpu == cpu_dev->id) 83 continue; 84 85 tcpu_dev = get_cpu_device(cpu); 86 if (!tcpu_dev) 87 continue; 88 89 tdomain = handle->perf_ops->device_domain_id(tcpu_dev); 90 if (tdomain == domain) 91 cpumask_set_cpu(cpu, cpumask); 92 } 93 94 return 0; 95 } 96 97 static int __maybe_unused 98 scmi_get_cpu_power(unsigned long *power, unsigned long *KHz, 99 struct device *cpu_dev) 100 { 101 unsigned long Hz; 102 int ret, domain; 103 104 domain = handle->perf_ops->device_domain_id(cpu_dev); 105 if (domain < 0) 106 return domain; 107 108 /* Get the power cost of the performance domain. */ 109 Hz = *KHz * 1000; 110 ret = handle->perf_ops->est_power_get(handle, domain, &Hz, power); 111 if (ret) 112 return ret; 113 114 /* The EM framework specifies the frequency in KHz. */ 115 *KHz = Hz / 1000; 116 117 return 0; 118 } 119 120 static int scmi_cpufreq_init(struct cpufreq_policy *policy) 121 { 122 int ret, nr_opp; 123 unsigned int latency; 124 struct device *cpu_dev; 125 struct scmi_data *priv; 126 struct cpufreq_frequency_table *freq_table; 127 struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power); 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 ret = handle->perf_ops->device_opps_add(handle, cpu_dev); 136 if (ret) { 137 dev_warn(cpu_dev, "failed to add opps to the device\n"); 138 return ret; 139 } 140 141 ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus); 142 if (ret) { 143 dev_warn(cpu_dev, "failed to get sharing cpumask\n"); 144 return ret; 145 } 146 147 ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus); 148 if (ret) { 149 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n", 150 __func__, ret); 151 return ret; 152 } 153 154 nr_opp = dev_pm_opp_get_opp_count(cpu_dev); 155 if (nr_opp <= 0) { 156 dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n"); 157 ret = -EPROBE_DEFER; 158 goto out_free_opp; 159 } 160 161 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 162 if (!priv) { 163 ret = -ENOMEM; 164 goto out_free_opp; 165 } 166 167 ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table); 168 if (ret) { 169 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret); 170 goto out_free_priv; 171 } 172 173 priv->cpu_dev = cpu_dev; 174 priv->domain_id = handle->perf_ops->device_domain_id(cpu_dev); 175 176 policy->driver_data = priv; 177 policy->freq_table = freq_table; 178 179 /* SCMI allows DVFS request for any domain from any CPU */ 180 policy->dvfs_possible_from_any_cpu = true; 181 182 latency = handle->perf_ops->transition_latency_get(handle, cpu_dev); 183 if (!latency) 184 latency = CPUFREQ_ETERNAL; 185 186 policy->cpuinfo.transition_latency = latency; 187 188 policy->fast_switch_possible = 189 handle->perf_ops->fast_switch_possible(handle, cpu_dev); 190 191 em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb, policy->cpus); 192 193 return 0; 194 195 out_free_priv: 196 kfree(priv); 197 out_free_opp: 198 dev_pm_opp_remove_all_dynamic(cpu_dev); 199 200 return ret; 201 } 202 203 static int scmi_cpufreq_exit(struct cpufreq_policy *policy) 204 { 205 struct scmi_data *priv = policy->driver_data; 206 207 dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table); 208 dev_pm_opp_remove_all_dynamic(priv->cpu_dev); 209 kfree(priv); 210 211 return 0; 212 } 213 214 static struct cpufreq_driver scmi_cpufreq_driver = { 215 .name = "scmi", 216 .flags = CPUFREQ_STICKY | CPUFREQ_HAVE_GOVERNOR_PER_POLICY | 217 CPUFREQ_NEED_INITIAL_FREQ_CHECK | 218 CPUFREQ_IS_COOLING_DEV, 219 .verify = cpufreq_generic_frequency_table_verify, 220 .attr = cpufreq_generic_attr, 221 .target_index = scmi_cpufreq_set_target, 222 .fast_switch = scmi_cpufreq_fast_switch, 223 .get = scmi_cpufreq_get_rate, 224 .init = scmi_cpufreq_init, 225 .exit = scmi_cpufreq_exit, 226 }; 227 228 static int scmi_cpufreq_probe(struct scmi_device *sdev) 229 { 230 int ret; 231 232 handle = sdev->handle; 233 234 if (!handle || !handle->perf_ops) 235 return -ENODEV; 236 237 ret = cpufreq_register_driver(&scmi_cpufreq_driver); 238 if (ret) { 239 dev_err(&sdev->dev, "%s: registering cpufreq failed, err: %d\n", 240 __func__, ret); 241 } 242 243 return ret; 244 } 245 246 static void scmi_cpufreq_remove(struct scmi_device *sdev) 247 { 248 cpufreq_unregister_driver(&scmi_cpufreq_driver); 249 } 250 251 static const struct scmi_device_id scmi_id_table[] = { 252 { SCMI_PROTOCOL_PERF, "cpufreq" }, 253 { }, 254 }; 255 MODULE_DEVICE_TABLE(scmi, scmi_id_table); 256 257 static struct scmi_driver scmi_cpufreq_drv = { 258 .name = "scmi-cpufreq", 259 .probe = scmi_cpufreq_probe, 260 .remove = scmi_cpufreq_remove, 261 .id_table = scmi_id_table, 262 }; 263 module_scmi_driver(scmi_cpufreq_drv); 264 265 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>"); 266 MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver"); 267 MODULE_LICENSE("GPL v2"); 268