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/cpu_cooling.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 struct thermal_cooling_device *cdev; 26 }; 27 28 static const struct scmi_handle *handle; 29 30 static unsigned int scmi_cpufreq_get_rate(unsigned int cpu) 31 { 32 struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu); 33 struct scmi_perf_ops *perf_ops = handle->perf_ops; 34 struct scmi_data *priv = policy->driver_data; 35 unsigned long rate; 36 int ret; 37 38 ret = perf_ops->freq_get(handle, 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 int ret; 53 struct scmi_data *priv = policy->driver_data; 54 struct scmi_perf_ops *perf_ops = handle->perf_ops; 55 u64 freq = policy->freq_table[index].frequency; 56 57 ret = perf_ops->freq_set(handle, priv->domain_id, freq * 1000, false); 58 if (!ret) 59 arch_set_freq_scale(policy->related_cpus, freq, 60 policy->cpuinfo.max_freq); 61 return ret; 62 } 63 64 static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy, 65 unsigned int target_freq) 66 { 67 struct scmi_data *priv = policy->driver_data; 68 struct scmi_perf_ops *perf_ops = handle->perf_ops; 69 70 if (!perf_ops->freq_set(handle, priv->domain_id, 71 target_freq * 1000, true)) { 72 arch_set_freq_scale(policy->related_cpus, target_freq, 73 policy->cpuinfo.max_freq); 74 return target_freq; 75 } 76 77 return 0; 78 } 79 80 static int 81 scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask) 82 { 83 int cpu, domain, tdomain; 84 struct device *tcpu_dev; 85 86 domain = handle->perf_ops->device_domain_id(cpu_dev); 87 if (domain < 0) 88 return domain; 89 90 for_each_possible_cpu(cpu) { 91 if (cpu == cpu_dev->id) 92 continue; 93 94 tcpu_dev = get_cpu_device(cpu); 95 if (!tcpu_dev) 96 continue; 97 98 tdomain = handle->perf_ops->device_domain_id(tcpu_dev); 99 if (tdomain == domain) 100 cpumask_set_cpu(cpu, cpumask); 101 } 102 103 return 0; 104 } 105 106 static int scmi_cpufreq_init(struct cpufreq_policy *policy) 107 { 108 int ret; 109 unsigned int latency; 110 struct device *cpu_dev; 111 struct scmi_data *priv; 112 struct cpufreq_frequency_table *freq_table; 113 114 cpu_dev = get_cpu_device(policy->cpu); 115 if (!cpu_dev) { 116 pr_err("failed to get cpu%d device\n", policy->cpu); 117 return -ENODEV; 118 } 119 120 ret = handle->perf_ops->device_opps_add(handle, cpu_dev); 121 if (ret) { 122 dev_warn(cpu_dev, "failed to add opps to the device\n"); 123 return ret; 124 } 125 126 ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus); 127 if (ret) { 128 dev_warn(cpu_dev, "failed to get sharing cpumask\n"); 129 return ret; 130 } 131 132 ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus); 133 if (ret) { 134 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n", 135 __func__, ret); 136 return ret; 137 } 138 139 ret = dev_pm_opp_get_opp_count(cpu_dev); 140 if (ret <= 0) { 141 dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n"); 142 ret = -EPROBE_DEFER; 143 goto out_free_opp; 144 } 145 146 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 147 if (!priv) { 148 ret = -ENOMEM; 149 goto out_free_opp; 150 } 151 152 ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table); 153 if (ret) { 154 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret); 155 goto out_free_priv; 156 } 157 158 priv->cpu_dev = cpu_dev; 159 priv->domain_id = handle->perf_ops->device_domain_id(cpu_dev); 160 161 policy->driver_data = priv; 162 policy->freq_table = freq_table; 163 164 /* SCMI allows DVFS request for any domain from any CPU */ 165 policy->dvfs_possible_from_any_cpu = true; 166 167 latency = handle->perf_ops->transition_latency_get(handle, cpu_dev); 168 if (!latency) 169 latency = CPUFREQ_ETERNAL; 170 171 policy->cpuinfo.transition_latency = latency; 172 173 policy->fast_switch_possible = true; 174 return 0; 175 176 out_free_priv: 177 kfree(priv); 178 out_free_opp: 179 dev_pm_opp_remove_all_dynamic(cpu_dev); 180 181 return ret; 182 } 183 184 static int scmi_cpufreq_exit(struct cpufreq_policy *policy) 185 { 186 struct scmi_data *priv = policy->driver_data; 187 188 cpufreq_cooling_unregister(priv->cdev); 189 dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table); 190 kfree(priv); 191 dev_pm_opp_remove_all_dynamic(priv->cpu_dev); 192 193 return 0; 194 } 195 196 static void scmi_cpufreq_ready(struct cpufreq_policy *policy) 197 { 198 struct scmi_data *priv = policy->driver_data; 199 200 priv->cdev = of_cpufreq_cooling_register(policy); 201 } 202 203 static struct cpufreq_driver scmi_cpufreq_driver = { 204 .name = "scmi", 205 .flags = CPUFREQ_STICKY | CPUFREQ_HAVE_GOVERNOR_PER_POLICY | 206 CPUFREQ_NEED_INITIAL_FREQ_CHECK, 207 .verify = cpufreq_generic_frequency_table_verify, 208 .attr = cpufreq_generic_attr, 209 .target_index = scmi_cpufreq_set_target, 210 .fast_switch = scmi_cpufreq_fast_switch, 211 .get = scmi_cpufreq_get_rate, 212 .init = scmi_cpufreq_init, 213 .exit = scmi_cpufreq_exit, 214 .ready = scmi_cpufreq_ready, 215 }; 216 217 static int scmi_cpufreq_probe(struct scmi_device *sdev) 218 { 219 int ret; 220 221 handle = sdev->handle; 222 223 if (!handle || !handle->perf_ops) 224 return -ENODEV; 225 226 ret = cpufreq_register_driver(&scmi_cpufreq_driver); 227 if (ret) { 228 dev_err(&sdev->dev, "%s: registering cpufreq failed, err: %d\n", 229 __func__, ret); 230 } 231 232 return ret; 233 } 234 235 static void scmi_cpufreq_remove(struct scmi_device *sdev) 236 { 237 cpufreq_unregister_driver(&scmi_cpufreq_driver); 238 } 239 240 static const struct scmi_device_id scmi_id_table[] = { 241 { SCMI_PROTOCOL_PERF }, 242 { }, 243 }; 244 MODULE_DEVICE_TABLE(scmi, scmi_id_table); 245 246 static struct scmi_driver scmi_cpufreq_drv = { 247 .name = "scmi-cpufreq", 248 .probe = scmi_cpufreq_probe, 249 .remove = scmi_cpufreq_remove, 250 .id_table = scmi_id_table, 251 }; 252 module_scmi_driver(scmi_cpufreq_drv); 253 254 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>"); 255 MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver"); 256 MODULE_LICENSE("GPL v2"); 257