1 // SPDX-License-Identifier: GPL-2.0
3 * System Control and Power Interface (SCMI) based CPUFreq Interface driver
5 * Copyright (C) 2018-2021 ARM Ltd.
6 * Sudeep Holla <sudeep.holla@arm.com>
9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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 #include <linux/units.h>
27 struct device *cpu_dev;
28 cpumask_var_t opp_shared_cpus;
31 static struct scmi_protocol_handle *ph;
32 static const struct scmi_perf_proto_ops *perf_ops;
34 static unsigned int scmi_cpufreq_get_rate(unsigned int cpu)
36 struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
37 struct scmi_data *priv = policy->driver_data;
41 ret = perf_ops->freq_get(ph, priv->domain_id, &rate, false);
48 * perf_ops->freq_set is not a synchronous, the actual OPP change will
49 * happen asynchronously and can get notified if the events are
50 * subscribed for by the SCMI firmware
53 scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
55 struct scmi_data *priv = policy->driver_data;
56 u64 freq = policy->freq_table[index].frequency;
58 return perf_ops->freq_set(ph, priv->domain_id, freq * 1000, false);
61 static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy,
62 unsigned int target_freq)
64 struct scmi_data *priv = policy->driver_data;
66 if (!perf_ops->freq_set(ph, priv->domain_id,
67 target_freq * 1000, true))
74 scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
76 int cpu, domain, tdomain;
77 struct device *tcpu_dev;
79 domain = perf_ops->device_domain_id(cpu_dev);
83 for_each_possible_cpu(cpu) {
84 if (cpu == cpu_dev->id)
87 tcpu_dev = get_cpu_device(cpu);
91 tdomain = perf_ops->device_domain_id(tcpu_dev);
92 if (tdomain == domain)
93 cpumask_set_cpu(cpu, cpumask);
99 static int __maybe_unused
100 scmi_get_cpu_power(struct device *cpu_dev, unsigned long *power,
103 bool power_scale_mw = perf_ops->power_scale_mw_get(ph);
107 domain = perf_ops->device_domain_id(cpu_dev);
111 /* Get the power cost of the performance domain. */
113 ret = perf_ops->est_power_get(ph, domain, &Hz, power);
117 /* Provide bigger resolution power to the Energy Model */
119 *power *= MICROWATT_PER_MILLIWATT;
121 /* The EM framework specifies the frequency in KHz. */
127 static int scmi_cpufreq_init(struct cpufreq_policy *policy)
130 unsigned int latency;
131 struct device *cpu_dev;
132 struct scmi_data *priv;
133 struct cpufreq_frequency_table *freq_table;
135 cpu_dev = get_cpu_device(policy->cpu);
137 pr_err("failed to get cpu%d device\n", policy->cpu);
141 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
145 if (!zalloc_cpumask_var(&priv->opp_shared_cpus, GFP_KERNEL)) {
150 /* Obtain CPUs that share SCMI performance controls */
151 ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus);
153 dev_warn(cpu_dev, "failed to get sharing cpumask\n");
154 goto out_free_cpumask;
158 * Obtain CPUs that share performance levels.
159 * The OPP 'sharing cpus' info may come from DT through an empty opp
160 * table and opp-shared.
162 ret = dev_pm_opp_of_get_sharing_cpus(cpu_dev, priv->opp_shared_cpus);
163 if (ret || cpumask_empty(priv->opp_shared_cpus)) {
165 * Either opp-table is not set or no opp-shared was found.
166 * Use the CPU mask from SCMI to designate CPUs sharing an OPP
169 cpumask_copy(priv->opp_shared_cpus, policy->cpus);
173 * A previous CPU may have marked OPPs as shared for a few CPUs, based on
174 * what OPP core provided. If the current CPU is part of those few, then
175 * there is no need to add OPPs again.
177 nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
179 ret = perf_ops->device_opps_add(ph, cpu_dev);
181 dev_warn(cpu_dev, "failed to add opps to the device\n");
182 goto out_free_cpumask;
185 nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
187 dev_err(cpu_dev, "%s: No OPPs for this device: %d\n",
194 ret = dev_pm_opp_set_sharing_cpus(cpu_dev, priv->opp_shared_cpus);
196 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
202 priv->nr_opp = nr_opp;
205 ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
207 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
211 priv->cpu_dev = cpu_dev;
212 priv->domain_id = perf_ops->device_domain_id(cpu_dev);
214 policy->driver_data = priv;
215 policy->freq_table = freq_table;
217 /* SCMI allows DVFS request for any domain from any CPU */
218 policy->dvfs_possible_from_any_cpu = true;
220 latency = perf_ops->transition_latency_get(ph, cpu_dev);
222 latency = CPUFREQ_ETERNAL;
224 policy->cpuinfo.transition_latency = latency;
226 policy->fast_switch_possible =
227 perf_ops->fast_switch_possible(ph, cpu_dev);
232 dev_pm_opp_remove_all_dynamic(cpu_dev);
235 free_cpumask_var(priv->opp_shared_cpus);
243 static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
245 struct scmi_data *priv = policy->driver_data;
247 dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
248 dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
249 free_cpumask_var(priv->opp_shared_cpus);
255 static void scmi_cpufreq_register_em(struct cpufreq_policy *policy)
257 struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
258 bool power_scale_mw = perf_ops->power_scale_mw_get(ph);
259 struct scmi_data *priv = policy->driver_data;
262 * This callback will be called for each policy, but we don't need to
263 * register with EM every time. Despite not being part of the same
264 * policy, some CPUs may still share their perf-domains, and a CPU from
265 * another policy may already have registered with EM on behalf of CPUs
271 em_dev_register_perf_domain(get_cpu_device(policy->cpu), priv->nr_opp,
272 &em_cb, priv->opp_shared_cpus,
276 static struct cpufreq_driver scmi_cpufreq_driver = {
278 .flags = CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
279 CPUFREQ_NEED_INITIAL_FREQ_CHECK |
280 CPUFREQ_IS_COOLING_DEV,
281 .verify = cpufreq_generic_frequency_table_verify,
282 .attr = cpufreq_generic_attr,
283 .target_index = scmi_cpufreq_set_target,
284 .fast_switch = scmi_cpufreq_fast_switch,
285 .get = scmi_cpufreq_get_rate,
286 .init = scmi_cpufreq_init,
287 .exit = scmi_cpufreq_exit,
288 .register_em = scmi_cpufreq_register_em,
291 static int scmi_cpufreq_probe(struct scmi_device *sdev)
294 struct device *dev = &sdev->dev;
295 const struct scmi_handle *handle;
297 handle = sdev->handle;
302 perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
303 if (IS_ERR(perf_ops))
304 return PTR_ERR(perf_ops);
306 #ifdef CONFIG_COMMON_CLK
307 /* dummy clock provider as needed by OPP if clocks property is used */
308 if (of_find_property(dev->of_node, "#clock-cells", NULL))
309 devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, NULL);
312 ret = cpufreq_register_driver(&scmi_cpufreq_driver);
314 dev_err(dev, "%s: registering cpufreq failed, err: %d\n",
321 static void scmi_cpufreq_remove(struct scmi_device *sdev)
323 cpufreq_unregister_driver(&scmi_cpufreq_driver);
326 static const struct scmi_device_id scmi_id_table[] = {
327 { SCMI_PROTOCOL_PERF, "cpufreq" },
330 MODULE_DEVICE_TABLE(scmi, scmi_id_table);
332 static struct scmi_driver scmi_cpufreq_drv = {
333 .name = "scmi-cpufreq",
334 .probe = scmi_cpufreq_probe,
335 .remove = scmi_cpufreq_remove,
336 .id_table = scmi_id_table,
338 module_scmi_driver(scmi_cpufreq_drv);
340 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
341 MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
342 MODULE_LICENSE("GPL v2");