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/pm_qos.h>
20 #include <linux/slab.h>
21 #include <linux/scmi_protocol.h>
22 #include <linux/types.h>
23 #include <linux/units.h>
24
25 struct scmi_data {
26 int domain_id;
27 int nr_opp;
28 struct device *cpu_dev;
29 cpumask_var_t opp_shared_cpus;
30 struct notifier_block limit_notify_nb;
31 struct freq_qos_request limits_freq_req;
32 };
33
34 static struct scmi_protocol_handle *ph;
35 static const struct scmi_perf_proto_ops *perf_ops;
36 static struct cpufreq_driver scmi_cpufreq_driver;
37
scmi_cpufreq_get_rate(unsigned int cpu)38 static unsigned int scmi_cpufreq_get_rate(unsigned int cpu)
39 {
40 struct cpufreq_policy *policy;
41 struct scmi_data *priv;
42 unsigned long rate;
43 int ret;
44
45 policy = cpufreq_cpu_get_raw(cpu);
46 if (unlikely(!policy))
47 return 0;
48
49 priv = policy->driver_data;
50
51 ret = perf_ops->freq_get(ph, priv->domain_id, &rate, false);
52 if (ret)
53 return 0;
54 return rate / 1000;
55 }
56
57 /*
58 * perf_ops->freq_set is not a synchronous, the actual OPP change will
59 * happen asynchronously and can get notified if the events are
60 * subscribed for by the SCMI firmware
61 */
62 static int
scmi_cpufreq_set_target(struct cpufreq_policy * policy,unsigned int index)63 scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
64 {
65 struct scmi_data *priv = policy->driver_data;
66 u64 freq = policy->freq_table[index].frequency;
67
68 return perf_ops->freq_set(ph, priv->domain_id, freq * 1000, false);
69 }
70
scmi_cpufreq_fast_switch(struct cpufreq_policy * policy,unsigned int target_freq)71 static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy,
72 unsigned int target_freq)
73 {
74 struct scmi_data *priv = policy->driver_data;
75 unsigned long freq = target_freq;
76
77 if (!perf_ops->freq_set(ph, priv->domain_id, freq * 1000, true))
78 return target_freq;
79
80 return 0;
81 }
82
scmi_cpu_domain_id(struct device * cpu_dev)83 static int scmi_cpu_domain_id(struct device *cpu_dev)
84 {
85 struct device_node *np = cpu_dev->of_node;
86 struct of_phandle_args domain_id;
87 int index;
88
89 if (of_parse_phandle_with_args(np, "clocks", "#clock-cells", 0,
90 &domain_id)) {
91 /* Find the corresponding index for power-domain "perf". */
92 index = of_property_match_string(np, "power-domain-names",
93 "perf");
94 if (index < 0)
95 return -EINVAL;
96
97 if (of_parse_phandle_with_args(np, "power-domains",
98 "#power-domain-cells", index,
99 &domain_id))
100 return -EINVAL;
101 }
102
103 return domain_id.args[0];
104 }
105
106 static int
scmi_get_sharing_cpus(struct device * cpu_dev,int domain,struct cpumask * cpumask)107 scmi_get_sharing_cpus(struct device *cpu_dev, int domain,
108 struct cpumask *cpumask)
109 {
110 int cpu, tdomain;
111 struct device *tcpu_dev;
112
113 for_each_present_cpu(cpu) {
114 if (cpu == cpu_dev->id)
115 continue;
116
117 tcpu_dev = get_cpu_device(cpu);
118 if (!tcpu_dev)
119 continue;
120
121 tdomain = scmi_cpu_domain_id(tcpu_dev);
122 if (tdomain == domain)
123 cpumask_set_cpu(cpu, cpumask);
124 }
125
126 return 0;
127 }
128
129 static int __maybe_unused
scmi_get_cpu_power(struct device * cpu_dev,unsigned long * power,unsigned long * KHz)130 scmi_get_cpu_power(struct device *cpu_dev, unsigned long *power,
131 unsigned long *KHz)
132 {
133 enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph);
134 unsigned long Hz;
135 int ret, domain;
136
137 domain = scmi_cpu_domain_id(cpu_dev);
138 if (domain < 0)
139 return domain;
140
141 /* Get the power cost of the performance domain. */
142 Hz = *KHz * 1000;
143 ret = perf_ops->est_power_get(ph, domain, &Hz, power);
144 if (ret)
145 return ret;
146
147 /* Convert the power to uW if it is mW (ignore bogoW) */
148 if (power_scale == SCMI_POWER_MILLIWATTS)
149 *power *= MICROWATT_PER_MILLIWATT;
150
151 /* The EM framework specifies the frequency in KHz. */
152 *KHz = Hz / 1000;
153
154 return 0;
155 }
156
157 static int
scmi_get_rate_limit(u32 domain,bool has_fast_switch)158 scmi_get_rate_limit(u32 domain, bool has_fast_switch)
159 {
160 int ret, rate_limit;
161
162 if (has_fast_switch) {
163 /*
164 * Fast channels are used whenever available,
165 * so use their rate_limit value if populated.
166 */
167 ret = perf_ops->fast_switch_rate_limit(ph, domain,
168 &rate_limit);
169 if (!ret && rate_limit)
170 return rate_limit;
171 }
172
173 ret = perf_ops->rate_limit_get(ph, domain, &rate_limit);
174 if (ret)
175 return 0;
176
177 return rate_limit;
178 }
179
scmi_limit_notify_cb(struct notifier_block * nb,unsigned long event,void * data)180 static int scmi_limit_notify_cb(struct notifier_block *nb, unsigned long event, void *data)
181 {
182 struct scmi_data *priv = container_of(nb, struct scmi_data, limit_notify_nb);
183 struct scmi_perf_limits_report *limit_notify = data;
184 unsigned int limit_freq_khz;
185 int ret;
186
187 limit_freq_khz = limit_notify->range_max_freq / HZ_PER_KHZ;
188
189 ret = freq_qos_update_request(&priv->limits_freq_req, limit_freq_khz);
190 if (ret < 0)
191 pr_warn("failed to update freq constraint: %d\n", ret);
192
193 return NOTIFY_OK;
194 }
195
scmi_cpufreq_init(struct cpufreq_policy * policy)196 static int scmi_cpufreq_init(struct cpufreq_policy *policy)
197 {
198 int ret, nr_opp, domain;
199 unsigned int latency;
200 struct device *cpu_dev;
201 struct scmi_data *priv;
202 struct cpufreq_frequency_table *freq_table;
203 struct scmi_device *sdev = cpufreq_get_driver_data();
204
205 cpu_dev = get_cpu_device(policy->cpu);
206 if (!cpu_dev) {
207 pr_err("failed to get cpu%d device\n", policy->cpu);
208 return -ENODEV;
209 }
210
211 domain = scmi_cpu_domain_id(cpu_dev);
212 if (domain < 0)
213 return domain;
214
215 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
216 if (!priv)
217 return -ENOMEM;
218
219 if (!zalloc_cpumask_var(&priv->opp_shared_cpus, GFP_KERNEL)) {
220 ret = -ENOMEM;
221 goto out_free_priv;
222 }
223
224 /* Obtain CPUs that share SCMI performance controls */
225 ret = scmi_get_sharing_cpus(cpu_dev, domain, policy->cpus);
226 if (ret) {
227 dev_warn(cpu_dev, "failed to get sharing cpumask\n");
228 goto out_free_cpumask;
229 }
230
231 /*
232 * Obtain CPUs that share performance levels.
233 * The OPP 'sharing cpus' info may come from DT through an empty opp
234 * table and opp-shared.
235 */
236 ret = dev_pm_opp_of_get_sharing_cpus(cpu_dev, priv->opp_shared_cpus);
237 if (ret || cpumask_empty(priv->opp_shared_cpus)) {
238 /*
239 * Either opp-table is not set or no opp-shared was found.
240 * Use the CPU mask from SCMI to designate CPUs sharing an OPP
241 * table.
242 */
243 cpumask_copy(priv->opp_shared_cpus, policy->cpus);
244 }
245
246 /*
247 * A previous CPU may have marked OPPs as shared for a few CPUs, based on
248 * what OPP core provided. If the current CPU is part of those few, then
249 * there is no need to add OPPs again.
250 */
251 nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
252 if (nr_opp <= 0) {
253 ret = perf_ops->device_opps_add(ph, cpu_dev, domain);
254 if (ret) {
255 dev_warn(cpu_dev, "failed to add opps to the device\n");
256 goto out_free_cpumask;
257 }
258
259 nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
260 if (nr_opp <= 0) {
261 dev_err(cpu_dev, "%s: No OPPs for this device: %d\n",
262 __func__, nr_opp);
263
264 ret = -ENODEV;
265 goto out_free_opp;
266 }
267
268 ret = dev_pm_opp_set_sharing_cpus(cpu_dev, priv->opp_shared_cpus);
269 if (ret) {
270 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
271 __func__, ret);
272
273 goto out_free_opp;
274 }
275
276 priv->nr_opp = nr_opp;
277 }
278
279 ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
280 if (ret) {
281 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
282 goto out_free_opp;
283 }
284
285 priv->cpu_dev = cpu_dev;
286 priv->domain_id = domain;
287
288 policy->driver_data = priv;
289 policy->freq_table = freq_table;
290
291 /* SCMI allows DVFS request for any domain from any CPU */
292 policy->dvfs_possible_from_any_cpu = true;
293
294 latency = perf_ops->transition_latency_get(ph, domain);
295 if (!latency)
296 latency = CPUFREQ_ETERNAL;
297
298 policy->cpuinfo.transition_latency = latency;
299
300 policy->fast_switch_possible =
301 perf_ops->fast_switch_possible(ph, domain);
302
303 policy->transition_delay_us =
304 scmi_get_rate_limit(domain, policy->fast_switch_possible);
305
306 ret = freq_qos_add_request(&policy->constraints, &priv->limits_freq_req, FREQ_QOS_MAX,
307 FREQ_QOS_MAX_DEFAULT_VALUE);
308 if (ret < 0) {
309 dev_err(cpu_dev, "failed to add qos limits request: %d\n", ret);
310 goto out_free_table;
311 }
312
313 priv->limit_notify_nb.notifier_call = scmi_limit_notify_cb;
314 ret = sdev->handle->notify_ops->event_notifier_register(sdev->handle, SCMI_PROTOCOL_PERF,
315 SCMI_EVENT_PERFORMANCE_LIMITS_CHANGED,
316 &priv->domain_id,
317 &priv->limit_notify_nb);
318 if (ret)
319 dev_warn(&sdev->dev,
320 "failed to register for limits change notifier for domain %d\n",
321 priv->domain_id);
322
323 return 0;
324
325 out_free_table:
326 dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table);
327 out_free_opp:
328 dev_pm_opp_remove_all_dynamic(cpu_dev);
329
330 out_free_cpumask:
331 free_cpumask_var(priv->opp_shared_cpus);
332
333 out_free_priv:
334 kfree(priv);
335
336 return ret;
337 }
338
scmi_cpufreq_exit(struct cpufreq_policy * policy)339 static void scmi_cpufreq_exit(struct cpufreq_policy *policy)
340 {
341 struct scmi_data *priv = policy->driver_data;
342 struct scmi_device *sdev = cpufreq_get_driver_data();
343
344 sdev->handle->notify_ops->event_notifier_unregister(sdev->handle, SCMI_PROTOCOL_PERF,
345 SCMI_EVENT_PERFORMANCE_LIMITS_CHANGED,
346 &priv->domain_id,
347 &priv->limit_notify_nb);
348 freq_qos_remove_request(&priv->limits_freq_req);
349 dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
350 dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
351 free_cpumask_var(priv->opp_shared_cpus);
352 kfree(priv);
353 }
354
scmi_cpufreq_register_em(struct cpufreq_policy * policy)355 static void scmi_cpufreq_register_em(struct cpufreq_policy *policy)
356 {
357 struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
358 enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph);
359 struct scmi_data *priv = policy->driver_data;
360 bool em_power_scale = false;
361
362 /*
363 * This callback will be called for each policy, but we don't need to
364 * register with EM every time. Despite not being part of the same
365 * policy, some CPUs may still share their perf-domains, and a CPU from
366 * another policy may already have registered with EM on behalf of CPUs
367 * of this policy.
368 */
369 if (!priv->nr_opp)
370 return;
371
372 if (power_scale == SCMI_POWER_MILLIWATTS
373 || power_scale == SCMI_POWER_MICROWATTS)
374 em_power_scale = true;
375
376 em_dev_register_perf_domain(get_cpu_device(policy->cpu), priv->nr_opp,
377 &em_cb, priv->opp_shared_cpus,
378 em_power_scale);
379 }
380
381 static struct cpufreq_driver scmi_cpufreq_driver = {
382 .name = "scmi",
383 .flags = CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
384 CPUFREQ_NEED_INITIAL_FREQ_CHECK |
385 CPUFREQ_IS_COOLING_DEV,
386 .verify = cpufreq_generic_frequency_table_verify,
387 .target_index = scmi_cpufreq_set_target,
388 .fast_switch = scmi_cpufreq_fast_switch,
389 .get = scmi_cpufreq_get_rate,
390 .init = scmi_cpufreq_init,
391 .exit = scmi_cpufreq_exit,
392 .register_em = scmi_cpufreq_register_em,
393 .set_boost = cpufreq_boost_set_sw,
394 };
395
scmi_dev_used_by_cpus(struct device * scmi_dev)396 static bool scmi_dev_used_by_cpus(struct device *scmi_dev)
397 {
398 struct device_node *scmi_np = dev_of_node(scmi_dev);
399 struct device_node *cpu_np, *np;
400 struct device *cpu_dev;
401 int cpu, idx;
402
403 if (!scmi_np)
404 return false;
405
406 for_each_possible_cpu(cpu) {
407 cpu_dev = get_cpu_device(cpu);
408 if (!cpu_dev)
409 continue;
410
411 cpu_np = dev_of_node(cpu_dev);
412
413 np = of_parse_phandle(cpu_np, "clocks", 0);
414 of_node_put(np);
415
416 if (np == scmi_np)
417 return true;
418
419 idx = of_property_match_string(cpu_np, "power-domain-names", "perf");
420 np = of_parse_phandle(cpu_np, "power-domains", idx);
421 of_node_put(np);
422
423 if (np == scmi_np)
424 return true;
425 }
426
427 return false;
428 }
429
scmi_cpufreq_probe(struct scmi_device * sdev)430 static int scmi_cpufreq_probe(struct scmi_device *sdev)
431 {
432 int ret;
433 struct device *dev = &sdev->dev;
434 const struct scmi_handle *handle;
435
436 handle = sdev->handle;
437
438 if (!handle || !scmi_dev_used_by_cpus(dev))
439 return -ENODEV;
440
441 scmi_cpufreq_driver.driver_data = sdev;
442
443 perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
444 if (IS_ERR(perf_ops))
445 return PTR_ERR(perf_ops);
446
447 #ifdef CONFIG_COMMON_CLK
448 /* dummy clock provider as needed by OPP if clocks property is used */
449 if (of_property_present(dev->of_node, "#clock-cells")) {
450 ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, NULL);
451 if (ret)
452 return dev_err_probe(dev, ret, "%s: registering clock provider failed\n", __func__);
453 }
454 #endif
455
456 ret = cpufreq_register_driver(&scmi_cpufreq_driver);
457 if (ret) {
458 dev_err(dev, "%s: registering cpufreq failed, err: %d\n",
459 __func__, ret);
460 }
461
462 return ret;
463 }
464
scmi_cpufreq_remove(struct scmi_device * sdev)465 static void scmi_cpufreq_remove(struct scmi_device *sdev)
466 {
467 cpufreq_unregister_driver(&scmi_cpufreq_driver);
468 }
469
470 static const struct scmi_device_id scmi_id_table[] = {
471 { SCMI_PROTOCOL_PERF, "cpufreq" },
472 { },
473 };
474 MODULE_DEVICE_TABLE(scmi, scmi_id_table);
475
476 static struct scmi_driver scmi_cpufreq_drv = {
477 .name = "scmi-cpufreq",
478 .probe = scmi_cpufreq_probe,
479 .remove = scmi_cpufreq_remove,
480 .id_table = scmi_id_table,
481 };
482 module_scmi_driver(scmi_cpufreq_drv);
483
484 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
485 MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
486 MODULE_LICENSE("GPL v2");
487