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))
73 static int scmi_cpu_domain_id(struct device *cpu_dev)
75 struct device_node *np = cpu_dev->of_node;
76 struct of_phandle_args domain_id;
79 if (of_parse_phandle_with_args(np, "clocks", "#clock-cells", 0,
81 /* Find the corresponding index for power-domain "perf". */
82 index = of_property_match_string(np, "power-domain-names",
87 if (of_parse_phandle_with_args(np, "power-domains",
88 "#power-domain-cells", index,
93 return domain_id.args[0];
97 scmi_get_sharing_cpus(struct device *cpu_dev, int domain,
98 struct cpumask *cpumask)
101 struct device *tcpu_dev;
103 for_each_possible_cpu(cpu) {
104 if (cpu == cpu_dev->id)
107 tcpu_dev = get_cpu_device(cpu);
111 tdomain = scmi_cpu_domain_id(tcpu_dev);
112 if (tdomain == domain)
113 cpumask_set_cpu(cpu, cpumask);
119 static int __maybe_unused
120 scmi_get_cpu_power(struct device *cpu_dev, unsigned long *power,
123 enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph);
127 domain = scmi_cpu_domain_id(cpu_dev);
131 /* Get the power cost of the performance domain. */
133 ret = perf_ops->est_power_get(ph, domain, &Hz, power);
137 /* Convert the power to uW if it is mW (ignore bogoW) */
138 if (power_scale == SCMI_POWER_MILLIWATTS)
139 *power *= MICROWATT_PER_MILLIWATT;
141 /* The EM framework specifies the frequency in KHz. */
147 static int scmi_cpufreq_init(struct cpufreq_policy *policy)
149 int ret, nr_opp, domain;
150 unsigned int latency;
151 struct device *cpu_dev;
152 struct scmi_data *priv;
153 struct cpufreq_frequency_table *freq_table;
155 cpu_dev = get_cpu_device(policy->cpu);
157 pr_err("failed to get cpu%d device\n", policy->cpu);
161 domain = scmi_cpu_domain_id(cpu_dev);
165 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
169 if (!zalloc_cpumask_var(&priv->opp_shared_cpus, GFP_KERNEL)) {
174 /* Obtain CPUs that share SCMI performance controls */
175 ret = scmi_get_sharing_cpus(cpu_dev, domain, policy->cpus);
177 dev_warn(cpu_dev, "failed to get sharing cpumask\n");
178 goto out_free_cpumask;
182 * Obtain CPUs that share performance levels.
183 * The OPP 'sharing cpus' info may come from DT through an empty opp
184 * table and opp-shared.
186 ret = dev_pm_opp_of_get_sharing_cpus(cpu_dev, priv->opp_shared_cpus);
187 if (ret || cpumask_empty(priv->opp_shared_cpus)) {
189 * Either opp-table is not set or no opp-shared was found.
190 * Use the CPU mask from SCMI to designate CPUs sharing an OPP
193 cpumask_copy(priv->opp_shared_cpus, policy->cpus);
197 * A previous CPU may have marked OPPs as shared for a few CPUs, based on
198 * what OPP core provided. If the current CPU is part of those few, then
199 * there is no need to add OPPs again.
201 nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
203 ret = perf_ops->device_opps_add(ph, cpu_dev, domain);
205 dev_warn(cpu_dev, "failed to add opps to the device\n");
206 goto out_free_cpumask;
209 nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
211 dev_err(cpu_dev, "%s: No OPPs for this device: %d\n",
218 ret = dev_pm_opp_set_sharing_cpus(cpu_dev, priv->opp_shared_cpus);
220 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
226 priv->nr_opp = nr_opp;
229 ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
231 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
235 priv->cpu_dev = cpu_dev;
236 priv->domain_id = domain;
238 policy->driver_data = priv;
239 policy->freq_table = freq_table;
241 /* SCMI allows DVFS request for any domain from any CPU */
242 policy->dvfs_possible_from_any_cpu = true;
244 latency = perf_ops->transition_latency_get(ph, domain);
246 latency = CPUFREQ_ETERNAL;
248 policy->cpuinfo.transition_latency = latency;
250 policy->fast_switch_possible =
251 perf_ops->fast_switch_possible(ph, domain);
256 dev_pm_opp_remove_all_dynamic(cpu_dev);
259 free_cpumask_var(priv->opp_shared_cpus);
267 static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
269 struct scmi_data *priv = policy->driver_data;
271 dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
272 dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
273 free_cpumask_var(priv->opp_shared_cpus);
279 static void scmi_cpufreq_register_em(struct cpufreq_policy *policy)
281 struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
282 enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph);
283 struct scmi_data *priv = policy->driver_data;
284 bool em_power_scale = false;
287 * This callback will be called for each policy, but we don't need to
288 * register with EM every time. Despite not being part of the same
289 * policy, some CPUs may still share their perf-domains, and a CPU from
290 * another policy may already have registered with EM on behalf of CPUs
296 if (power_scale == SCMI_POWER_MILLIWATTS
297 || power_scale == SCMI_POWER_MICROWATTS)
298 em_power_scale = true;
300 em_dev_register_perf_domain(get_cpu_device(policy->cpu), priv->nr_opp,
301 &em_cb, priv->opp_shared_cpus,
305 static struct cpufreq_driver scmi_cpufreq_driver = {
307 .flags = CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
308 CPUFREQ_NEED_INITIAL_FREQ_CHECK |
309 CPUFREQ_IS_COOLING_DEV,
310 .verify = cpufreq_generic_frequency_table_verify,
311 .attr = cpufreq_generic_attr,
312 .target_index = scmi_cpufreq_set_target,
313 .fast_switch = scmi_cpufreq_fast_switch,
314 .get = scmi_cpufreq_get_rate,
315 .init = scmi_cpufreq_init,
316 .exit = scmi_cpufreq_exit,
317 .register_em = scmi_cpufreq_register_em,
320 static int scmi_cpufreq_probe(struct scmi_device *sdev)
323 struct device *dev = &sdev->dev;
324 const struct scmi_handle *handle;
326 handle = sdev->handle;
331 perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
332 if (IS_ERR(perf_ops))
333 return PTR_ERR(perf_ops);
335 #ifdef CONFIG_COMMON_CLK
336 /* dummy clock provider as needed by OPP if clocks property is used */
337 if (of_property_present(dev->of_node, "#clock-cells")) {
338 ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, NULL);
340 return dev_err_probe(dev, ret, "%s: registering clock provider failed\n", __func__);
344 ret = cpufreq_register_driver(&scmi_cpufreq_driver);
346 dev_err(dev, "%s: registering cpufreq failed, err: %d\n",
353 static void scmi_cpufreq_remove(struct scmi_device *sdev)
355 cpufreq_unregister_driver(&scmi_cpufreq_driver);
358 static const struct scmi_device_id scmi_id_table[] = {
359 { SCMI_PROTOCOL_PERF, "cpufreq" },
362 MODULE_DEVICE_TABLE(scmi, scmi_id_table);
364 static struct scmi_driver scmi_cpufreq_drv = {
365 .name = "scmi-cpufreq",
366 .probe = scmi_cpufreq_probe,
367 .remove = scmi_cpufreq_remove,
368 .id_table = scmi_id_table,
370 module_scmi_driver(scmi_cpufreq_drv);
372 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
373 MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
374 MODULE_LICENSE("GPL v2");