1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * System Control and Power Interface (SCMI) based CPUFreq Interface driver
4 *
5 * Copyright (C) 2018-2021 ARM Ltd.
6 * Sudeep Holla <sudeep.holla@arm.com>
7 */
8
9 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
10
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>
23
24 struct scmi_data {
25 int domain_id;
26 int nr_opp;
27 struct device *cpu_dev;
28 cpumask_var_t opp_shared_cpus;
29 };
30
31 static struct scmi_protocol_handle *ph;
32 static const struct scmi_perf_proto_ops *perf_ops;
33 static struct cpufreq_driver scmi_cpufreq_driver;
34
scmi_cpufreq_get_rate(unsigned int cpu)35 static unsigned int scmi_cpufreq_get_rate(unsigned int cpu)
36 {
37 struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
38 struct scmi_data *priv = policy->driver_data;
39 unsigned long rate;
40 int ret;
41
42 ret = perf_ops->freq_get(ph, priv->domain_id, &rate, false);
43 if (ret)
44 return 0;
45 return rate / 1000;
46 }
47
48 /*
49 * perf_ops->freq_set is not a synchronous, the actual OPP change will
50 * happen asynchronously and can get notified if the events are
51 * subscribed for by the SCMI firmware
52 */
53 static int
scmi_cpufreq_set_target(struct cpufreq_policy * policy,unsigned int index)54 scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
55 {
56 struct scmi_data *priv = policy->driver_data;
57 u64 freq = policy->freq_table[index].frequency;
58
59 return perf_ops->freq_set(ph, priv->domain_id, freq * 1000, false);
60 }
61
scmi_cpufreq_fast_switch(struct cpufreq_policy * policy,unsigned int target_freq)62 static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy,
63 unsigned int target_freq)
64 {
65 struct scmi_data *priv = policy->driver_data;
66 unsigned long freq = target_freq;
67
68 if (!perf_ops->freq_set(ph, priv->domain_id, freq * 1000, true))
69 return target_freq;
70
71 return 0;
72 }
73
scmi_cpu_domain_id(struct device * cpu_dev)74 static int scmi_cpu_domain_id(struct device *cpu_dev)
75 {
76 struct device_node *np = cpu_dev->of_node;
77 struct of_phandle_args domain_id;
78 int index;
79
80 if (of_parse_phandle_with_args(np, "clocks", "#clock-cells", 0,
81 &domain_id)) {
82 /* Find the corresponding index for power-domain "perf". */
83 index = of_property_match_string(np, "power-domain-names",
84 "perf");
85 if (index < 0)
86 return -EINVAL;
87
88 if (of_parse_phandle_with_args(np, "power-domains",
89 "#power-domain-cells", index,
90 &domain_id))
91 return -EINVAL;
92 }
93
94 return domain_id.args[0];
95 }
96
97 static int
scmi_get_sharing_cpus(struct device * cpu_dev,int domain,struct cpumask * cpumask)98 scmi_get_sharing_cpus(struct device *cpu_dev, int domain,
99 struct cpumask *cpumask)
100 {
101 int cpu, tdomain;
102 struct device *tcpu_dev;
103
104 for_each_possible_cpu(cpu) {
105 if (cpu == cpu_dev->id)
106 continue;
107
108 tcpu_dev = get_cpu_device(cpu);
109 if (!tcpu_dev)
110 continue;
111
112 tdomain = scmi_cpu_domain_id(tcpu_dev);
113 if (tdomain == domain)
114 cpumask_set_cpu(cpu, cpumask);
115 }
116
117 return 0;
118 }
119
120 static int __maybe_unused
scmi_get_cpu_power(struct device * cpu_dev,unsigned long * power,unsigned long * KHz)121 scmi_get_cpu_power(struct device *cpu_dev, unsigned long *power,
122 unsigned long *KHz)
123 {
124 enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph);
125 unsigned long Hz;
126 int ret, domain;
127
128 domain = scmi_cpu_domain_id(cpu_dev);
129 if (domain < 0)
130 return domain;
131
132 /* Get the power cost of the performance domain. */
133 Hz = *KHz * 1000;
134 ret = perf_ops->est_power_get(ph, domain, &Hz, power);
135 if (ret)
136 return ret;
137
138 /* Convert the power to uW if it is mW (ignore bogoW) */
139 if (power_scale == SCMI_POWER_MILLIWATTS)
140 *power *= MICROWATT_PER_MILLIWATT;
141
142 /* The EM framework specifies the frequency in KHz. */
143 *KHz = Hz / 1000;
144
145 return 0;
146 }
147
148 static int
scmi_get_rate_limit(u32 domain,bool has_fast_switch)149 scmi_get_rate_limit(u32 domain, bool has_fast_switch)
150 {
151 int ret, rate_limit;
152
153 if (has_fast_switch) {
154 /*
155 * Fast channels are used whenever available,
156 * so use their rate_limit value if populated.
157 */
158 ret = perf_ops->fast_switch_rate_limit(ph, domain,
159 &rate_limit);
160 if (!ret && rate_limit)
161 return rate_limit;
162 }
163
164 ret = perf_ops->rate_limit_get(ph, domain, &rate_limit);
165 if (ret)
166 return 0;
167
168 return rate_limit;
169 }
170
171 static struct freq_attr *scmi_cpufreq_hw_attr[] = {
172 &cpufreq_freq_attr_scaling_available_freqs,
173 NULL,
174 NULL,
175 };
176
scmi_cpufreq_init(struct cpufreq_policy * policy)177 static int scmi_cpufreq_init(struct cpufreq_policy *policy)
178 {
179 int ret, nr_opp, domain;
180 unsigned int latency;
181 struct device *cpu_dev;
182 struct scmi_data *priv;
183 struct cpufreq_frequency_table *freq_table;
184
185 cpu_dev = get_cpu_device(policy->cpu);
186 if (!cpu_dev) {
187 pr_err("failed to get cpu%d device\n", policy->cpu);
188 return -ENODEV;
189 }
190
191 domain = scmi_cpu_domain_id(cpu_dev);
192 if (domain < 0)
193 return domain;
194
195 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
196 if (!priv)
197 return -ENOMEM;
198
199 if (!zalloc_cpumask_var(&priv->opp_shared_cpus, GFP_KERNEL)) {
200 ret = -ENOMEM;
201 goto out_free_priv;
202 }
203
204 /* Obtain CPUs that share SCMI performance controls */
205 ret = scmi_get_sharing_cpus(cpu_dev, domain, policy->cpus);
206 if (ret) {
207 dev_warn(cpu_dev, "failed to get sharing cpumask\n");
208 goto out_free_cpumask;
209 }
210
211 /*
212 * Obtain CPUs that share performance levels.
213 * The OPP 'sharing cpus' info may come from DT through an empty opp
214 * table and opp-shared.
215 */
216 ret = dev_pm_opp_of_get_sharing_cpus(cpu_dev, priv->opp_shared_cpus);
217 if (ret || cpumask_empty(priv->opp_shared_cpus)) {
218 /*
219 * Either opp-table is not set or no opp-shared was found.
220 * Use the CPU mask from SCMI to designate CPUs sharing an OPP
221 * table.
222 */
223 cpumask_copy(priv->opp_shared_cpus, policy->cpus);
224 }
225
226 /*
227 * A previous CPU may have marked OPPs as shared for a few CPUs, based on
228 * what OPP core provided. If the current CPU is part of those few, then
229 * there is no need to add OPPs again.
230 */
231 nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
232 if (nr_opp <= 0) {
233 ret = perf_ops->device_opps_add(ph, cpu_dev, domain);
234 if (ret) {
235 dev_warn(cpu_dev, "failed to add opps to the device\n");
236 goto out_free_cpumask;
237 }
238
239 nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
240 if (nr_opp <= 0) {
241 dev_err(cpu_dev, "%s: No OPPs for this device: %d\n",
242 __func__, nr_opp);
243
244 ret = -ENODEV;
245 goto out_free_opp;
246 }
247
248 ret = dev_pm_opp_set_sharing_cpus(cpu_dev, priv->opp_shared_cpus);
249 if (ret) {
250 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
251 __func__, ret);
252
253 goto out_free_opp;
254 }
255
256 priv->nr_opp = nr_opp;
257 }
258
259 ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
260 if (ret) {
261 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
262 goto out_free_opp;
263 }
264
265 priv->cpu_dev = cpu_dev;
266 priv->domain_id = domain;
267
268 policy->driver_data = priv;
269 policy->freq_table = freq_table;
270
271 /* SCMI allows DVFS request for any domain from any CPU */
272 policy->dvfs_possible_from_any_cpu = true;
273
274 latency = perf_ops->transition_latency_get(ph, domain);
275 if (!latency)
276 latency = CPUFREQ_ETERNAL;
277
278 policy->cpuinfo.transition_latency = latency;
279
280 policy->fast_switch_possible =
281 perf_ops->fast_switch_possible(ph, domain);
282
283 policy->transition_delay_us =
284 scmi_get_rate_limit(domain, policy->fast_switch_possible);
285
286 if (policy_has_boost_freq(policy)) {
287 ret = cpufreq_enable_boost_support();
288 if (ret) {
289 dev_warn(cpu_dev, "failed to enable boost: %d\n", ret);
290 goto out_free_opp;
291 } else {
292 scmi_cpufreq_hw_attr[1] = &cpufreq_freq_attr_scaling_boost_freqs;
293 scmi_cpufreq_driver.boost_enabled = true;
294 }
295 }
296
297 return 0;
298
299 out_free_opp:
300 dev_pm_opp_remove_all_dynamic(cpu_dev);
301
302 out_free_cpumask:
303 free_cpumask_var(priv->opp_shared_cpus);
304
305 out_free_priv:
306 kfree(priv);
307
308 return ret;
309 }
310
scmi_cpufreq_exit(struct cpufreq_policy * policy)311 static void scmi_cpufreq_exit(struct cpufreq_policy *policy)
312 {
313 struct scmi_data *priv = policy->driver_data;
314
315 dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
316 dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
317 free_cpumask_var(priv->opp_shared_cpus);
318 kfree(priv);
319 }
320
scmi_cpufreq_register_em(struct cpufreq_policy * policy)321 static void scmi_cpufreq_register_em(struct cpufreq_policy *policy)
322 {
323 struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
324 enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph);
325 struct scmi_data *priv = policy->driver_data;
326 bool em_power_scale = false;
327
328 /*
329 * This callback will be called for each policy, but we don't need to
330 * register with EM every time. Despite not being part of the same
331 * policy, some CPUs may still share their perf-domains, and a CPU from
332 * another policy may already have registered with EM on behalf of CPUs
333 * of this policy.
334 */
335 if (!priv->nr_opp)
336 return;
337
338 if (power_scale == SCMI_POWER_MILLIWATTS
339 || power_scale == SCMI_POWER_MICROWATTS)
340 em_power_scale = true;
341
342 em_dev_register_perf_domain(get_cpu_device(policy->cpu), priv->nr_opp,
343 &em_cb, priv->opp_shared_cpus,
344 em_power_scale);
345 }
346
347 static struct cpufreq_driver scmi_cpufreq_driver = {
348 .name = "scmi",
349 .flags = CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
350 CPUFREQ_NEED_INITIAL_FREQ_CHECK |
351 CPUFREQ_IS_COOLING_DEV,
352 .verify = cpufreq_generic_frequency_table_verify,
353 .attr = scmi_cpufreq_hw_attr,
354 .target_index = scmi_cpufreq_set_target,
355 .fast_switch = scmi_cpufreq_fast_switch,
356 .get = scmi_cpufreq_get_rate,
357 .init = scmi_cpufreq_init,
358 .exit = scmi_cpufreq_exit,
359 .register_em = scmi_cpufreq_register_em,
360 };
361
scmi_cpufreq_probe(struct scmi_device * sdev)362 static int scmi_cpufreq_probe(struct scmi_device *sdev)
363 {
364 int ret;
365 struct device *dev = &sdev->dev;
366 const struct scmi_handle *handle;
367
368 handle = sdev->handle;
369
370 if (!handle)
371 return -ENODEV;
372
373 perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
374 if (IS_ERR(perf_ops))
375 return PTR_ERR(perf_ops);
376
377 #ifdef CONFIG_COMMON_CLK
378 /* dummy clock provider as needed by OPP if clocks property is used */
379 if (of_property_present(dev->of_node, "#clock-cells")) {
380 ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, NULL);
381 if (ret)
382 return dev_err_probe(dev, ret, "%s: registering clock provider failed\n", __func__);
383 }
384 #endif
385
386 ret = cpufreq_register_driver(&scmi_cpufreq_driver);
387 if (ret) {
388 dev_err(dev, "%s: registering cpufreq failed, err: %d\n",
389 __func__, ret);
390 }
391
392 return ret;
393 }
394
scmi_cpufreq_remove(struct scmi_device * sdev)395 static void scmi_cpufreq_remove(struct scmi_device *sdev)
396 {
397 cpufreq_unregister_driver(&scmi_cpufreq_driver);
398 }
399
400 static const struct scmi_device_id scmi_id_table[] = {
401 { SCMI_PROTOCOL_PERF, "cpufreq" },
402 { },
403 };
404 MODULE_DEVICE_TABLE(scmi, scmi_id_table);
405
406 static struct scmi_driver scmi_cpufreq_drv = {
407 .name = "scmi-cpufreq",
408 .probe = scmi_cpufreq_probe,
409 .remove = scmi_cpufreq_remove,
410 .id_table = scmi_id_table,
411 };
412 module_scmi_driver(scmi_cpufreq_drv);
413
414 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
415 MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
416 MODULE_LICENSE("GPL v2");
417