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/of.h>
19#include <linux/pm_opp.h>
20#include <linux/pm_qos.h>
21#include <linux/slab.h>
22#include <linux/scmi_protocol.h>
23#include <linux/types.h>
24#include <linux/units.h>
25
26struct scmi_data {
27 int domain_id;
28 int nr_opp;
29 struct device *cpu_dev;
30 cpumask_var_t opp_shared_cpus;
31 struct notifier_block limit_notify_nb;
32 struct freq_qos_request limits_freq_req;
33};
34
35static struct scmi_protocol_handle *ph;
36static const struct scmi_perf_proto_ops *perf_ops;
37static struct cpufreq_driver scmi_cpufreq_driver;
38
39static unsigned int scmi_cpufreq_get_rate(unsigned int cpu)
40{
41 struct cpufreq_policy *policy;
42 struct scmi_data *priv;
43 unsigned long rate;
44 int ret;
45
46 policy = cpufreq_cpu_get_raw(cpu);
47 if (unlikely(!policy))
48 return 0;
49
50 priv = policy->driver_data;
51
52 ret = perf_ops->freq_get(ph, priv->domain_id, &rate, false);
53 if (ret)
54 return 0;
55 return rate / 1000;
56}
57
58/*
59 * perf_ops->freq_set is not a synchronous, the actual OPP change will
60 * happen asynchronously and can get notified if the events are
61 * subscribed for by the SCMI firmware
62 */
63static int
64scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
65{
66 struct scmi_data *priv = policy->driver_data;
67 u64 freq = policy->freq_table[index].frequency;
68
69 return perf_ops->freq_set(ph, priv->domain_id, freq * 1000, false);
70}
71
72static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy,
73 unsigned int target_freq)
74{
75 struct scmi_data *priv = policy->driver_data;
76 unsigned long freq = target_freq;
77
78 if (!perf_ops->freq_set(ph, priv->domain_id, freq * 1000, true))
79 return target_freq;
80
81 return 0;
82}
83
84static int scmi_cpu_domain_id(struct device *cpu_dev)
85{
86 struct device_node *np = cpu_dev->of_node;
87 struct of_phandle_args domain_id;
88 int index;
89
90 if (of_parse_phandle_with_args(np, list_name: "clocks", cells_name: "#clock-cells", index: 0,
91 out_args: &domain_id)) {
92 /* Find the corresponding index for power-domain "perf". */
93 index = of_property_match_string(np, propname: "power-domain-names",
94 string: "perf");
95 if (index < 0)
96 return -EINVAL;
97
98 if (of_parse_phandle_with_args(np, list_name: "power-domains",
99 cells_name: "#power-domain-cells", index,
100 out_args: &domain_id))
101 return -EINVAL;
102 }
103
104 return domain_id.args[0];
105}
106
107static int
108scmi_get_sharing_cpus(struct device *cpu_dev, int domain,
109 struct cpumask *cpumask)
110{
111 int cpu, tdomain;
112 struct device *tcpu_dev;
113
114 for_each_present_cpu(cpu) {
115 if (cpu == cpu_dev->id)
116 continue;
117
118 tcpu_dev = get_cpu_device(cpu);
119 if (!tcpu_dev)
120 continue;
121
122 tdomain = scmi_cpu_domain_id(cpu_dev: tcpu_dev);
123 if (tdomain == domain)
124 cpumask_set_cpu(cpu, dstp: cpumask);
125 }
126
127 return 0;
128}
129
130static int __maybe_unused
131scmi_get_cpu_power(struct device *cpu_dev, unsigned long *power,
132 unsigned long *KHz)
133{
134 enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph);
135 unsigned long Hz;
136 int ret, domain;
137
138 domain = scmi_cpu_domain_id(cpu_dev);
139 if (domain < 0)
140 return domain;
141
142 /* Get the power cost of the performance domain. */
143 Hz = *KHz * 1000;
144 ret = perf_ops->est_power_get(ph, domain, &Hz, power);
145 if (ret)
146 return ret;
147
148 /* Convert the power to uW if it is mW (ignore bogoW) */
149 if (power_scale == SCMI_POWER_MILLIWATTS)
150 *power *= MICROWATT_PER_MILLIWATT;
151
152 /* The EM framework specifies the frequency in KHz. */
153 *KHz = Hz / 1000;
154
155 return 0;
156}
157
158static int
159scmi_get_rate_limit(u32 domain, bool has_fast_switch)
160{
161 int ret, rate_limit;
162
163 if (has_fast_switch) {
164 /*
165 * Fast channels are used whenever available,
166 * so use their rate_limit value if populated.
167 */
168 ret = perf_ops->fast_switch_rate_limit(ph, domain,
169 &rate_limit);
170 if (!ret && rate_limit)
171 return rate_limit;
172 }
173
174 ret = perf_ops->rate_limit_get(ph, domain, &rate_limit);
175 if (ret)
176 return 0;
177
178 return rate_limit;
179}
180
181static int scmi_limit_notify_cb(struct notifier_block *nb, unsigned long event, void *data)
182{
183 struct scmi_data *priv = container_of(nb, struct scmi_data, limit_notify_nb);
184 struct scmi_perf_limits_report *limit_notify = data;
185 unsigned int limit_freq_khz;
186 int ret;
187
188 limit_freq_khz = limit_notify->range_max_freq / HZ_PER_KHZ;
189
190 ret = freq_qos_update_request(req: &priv->limits_freq_req, new_value: limit_freq_khz);
191 if (ret < 0)
192 pr_warn("failed to update freq constraint: %d\n", ret);
193
194 return NOTIFY_OK;
195}
196
197static int scmi_cpufreq_init(struct cpufreq_policy *policy)
198{
199 int ret, nr_opp, domain;
200 unsigned int latency;
201 struct device *cpu_dev;
202 struct scmi_data *priv;
203 struct cpufreq_frequency_table *freq_table;
204 struct scmi_device *sdev = cpufreq_get_driver_data();
205
206 cpu_dev = get_cpu_device(cpu: policy->cpu);
207 if (!cpu_dev) {
208 pr_err("failed to get cpu%d device\n", policy->cpu);
209 return -ENODEV;
210 }
211
212 domain = scmi_cpu_domain_id(cpu_dev);
213 if (domain < 0)
214 return domain;
215
216 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
217 if (!priv)
218 return -ENOMEM;
219
220 if (!zalloc_cpumask_var(mask: &priv->opp_shared_cpus, GFP_KERNEL)) {
221 ret = -ENOMEM;
222 goto out_free_priv;
223 }
224
225 /* Obtain CPUs that share SCMI performance controls */
226 ret = scmi_get_sharing_cpus(cpu_dev, domain, cpumask: policy->cpus);
227 if (ret) {
228 dev_warn(cpu_dev, "failed to get sharing cpumask\n");
229 goto out_free_cpumask;
230 }
231
232 /*
233 * Obtain CPUs that share performance levels.
234 * The OPP 'sharing cpus' info may come from DT through an empty opp
235 * table and opp-shared.
236 */
237 ret = dev_pm_opp_of_get_sharing_cpus(cpu_dev, cpumask: priv->opp_shared_cpus);
238 if (ret || cpumask_empty(srcp: priv->opp_shared_cpus)) {
239 /*
240 * Either opp-table is not set or no opp-shared was found.
241 * Use the CPU mask from SCMI to designate CPUs sharing an OPP
242 * table.
243 */
244 cpumask_copy(dstp: priv->opp_shared_cpus, srcp: policy->cpus);
245 }
246
247 /*
248 * A previous CPU may have marked OPPs as shared for a few CPUs, based on
249 * what OPP core provided. If the current CPU is part of those few, then
250 * there is no need to add OPPs again.
251 */
252 nr_opp = dev_pm_opp_get_opp_count(dev: cpu_dev);
253 if (nr_opp <= 0) {
254 ret = perf_ops->device_opps_add(ph, cpu_dev, domain);
255 if (ret) {
256 dev_warn(cpu_dev, "failed to add opps to the device\n");
257 goto out_free_cpumask;
258 }
259
260 nr_opp = dev_pm_opp_get_opp_count(dev: cpu_dev);
261 if (nr_opp <= 0) {
262 dev_err(cpu_dev, "%s: No OPPs for this device: %d\n",
263 __func__, nr_opp);
264
265 ret = -ENODEV;
266 goto out_free_opp;
267 }
268
269 ret = dev_pm_opp_set_sharing_cpus(cpu_dev, cpumask: priv->opp_shared_cpus);
270 if (ret) {
271 dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
272 __func__, ret);
273
274 goto out_free_opp;
275 }
276
277 priv->nr_opp = nr_opp;
278 }
279
280 ret = dev_pm_opp_init_cpufreq_table(dev: cpu_dev, table: &freq_table);
281 if (ret) {
282 dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
283 goto out_free_opp;
284 }
285
286 priv->cpu_dev = cpu_dev;
287 priv->domain_id = domain;
288
289 policy->driver_data = priv;
290 policy->freq_table = freq_table;
291
292 /* SCMI allows DVFS request for any domain from any CPU */
293 policy->dvfs_possible_from_any_cpu = true;
294
295 latency = perf_ops->transition_latency_get(ph, domain);
296 if (!latency)
297 latency = CPUFREQ_DEFAULT_TRANSITION_LATENCY_NS;
298
299 policy->cpuinfo.transition_latency = latency;
300
301 policy->fast_switch_possible =
302 perf_ops->fast_switch_possible(ph, domain);
303
304 policy->transition_delay_us =
305 scmi_get_rate_limit(domain, has_fast_switch: policy->fast_switch_possible);
306
307 ret = freq_qos_add_request(qos: &policy->constraints, req: &priv->limits_freq_req, type: FREQ_QOS_MAX,
308 FREQ_QOS_MAX_DEFAULT_VALUE);
309 if (ret < 0) {
310 dev_err(cpu_dev, "failed to add qos limits request: %d\n", ret);
311 goto out_free_table;
312 }
313
314 priv->limit_notify_nb.notifier_call = scmi_limit_notify_cb;
315 ret = sdev->handle->notify_ops->event_notifier_register(sdev->handle, SCMI_PROTOCOL_PERF,
316 SCMI_EVENT_PERFORMANCE_LIMITS_CHANGED,
317 &priv->domain_id,
318 &priv->limit_notify_nb);
319 if (ret)
320 dev_warn(&sdev->dev,
321 "failed to register for limits change notifier for domain %d\n",
322 priv->domain_id);
323
324 return 0;
325
326out_free_table:
327 dev_pm_opp_free_cpufreq_table(dev: cpu_dev, table: &freq_table);
328out_free_opp:
329 dev_pm_opp_remove_all_dynamic(dev: cpu_dev);
330
331out_free_cpumask:
332 free_cpumask_var(mask: priv->opp_shared_cpus);
333
334out_free_priv:
335 kfree(objp: priv);
336
337 return ret;
338}
339
340static void scmi_cpufreq_exit(struct cpufreq_policy *policy)
341{
342 struct scmi_data *priv = policy->driver_data;
343 struct scmi_device *sdev = cpufreq_get_driver_data();
344
345 sdev->handle->notify_ops->event_notifier_unregister(sdev->handle, SCMI_PROTOCOL_PERF,
346 SCMI_EVENT_PERFORMANCE_LIMITS_CHANGED,
347 &priv->domain_id,
348 &priv->limit_notify_nb);
349 freq_qos_remove_request(req: &priv->limits_freq_req);
350 dev_pm_opp_free_cpufreq_table(dev: priv->cpu_dev, table: &policy->freq_table);
351 dev_pm_opp_remove_all_dynamic(dev: priv->cpu_dev);
352 free_cpumask_var(mask: priv->opp_shared_cpus);
353 kfree(objp: priv);
354}
355
356static void scmi_cpufreq_register_em(struct cpufreq_policy *policy)
357{
358 struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
359 enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph);
360 struct scmi_data *priv = policy->driver_data;
361 bool em_power_scale = false;
362
363 /*
364 * This callback will be called for each policy, but we don't need to
365 * register with EM every time. Despite not being part of the same
366 * policy, some CPUs may still share their perf-domains, and a CPU from
367 * another policy may already have registered with EM on behalf of CPUs
368 * of this policy.
369 */
370 if (!priv->nr_opp)
371 return;
372
373 if (power_scale == SCMI_POWER_MILLIWATTS
374 || power_scale == SCMI_POWER_MICROWATTS)
375 em_power_scale = true;
376
377 em_dev_register_perf_domain(dev: get_cpu_device(cpu: policy->cpu), nr_states: priv->nr_opp,
378 cb: &em_cb, cpus: priv->opp_shared_cpus,
379 microwatts: em_power_scale);
380}
381
382static struct cpufreq_driver scmi_cpufreq_driver = {
383 .name = "scmi",
384 .flags = CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
385 CPUFREQ_NEED_INITIAL_FREQ_CHECK |
386 CPUFREQ_IS_COOLING_DEV,
387 .verify = cpufreq_generic_frequency_table_verify,
388 .target_index = scmi_cpufreq_set_target,
389 .fast_switch = scmi_cpufreq_fast_switch,
390 .get = scmi_cpufreq_get_rate,
391 .init = scmi_cpufreq_init,
392 .exit = scmi_cpufreq_exit,
393 .register_em = scmi_cpufreq_register_em,
394 .set_boost = cpufreq_boost_set_sw,
395};
396
397static bool scmi_dev_used_by_cpus(struct device *scmi_dev)
398{
399 struct device_node *scmi_np = dev_of_node(dev: scmi_dev);
400 struct device_node *cpu_np, *np;
401 struct device *cpu_dev;
402 int cpu, idx;
403
404 if (!scmi_np)
405 return false;
406
407 for_each_possible_cpu(cpu) {
408 cpu_dev = get_cpu_device(cpu);
409 if (!cpu_dev)
410 continue;
411
412 cpu_np = dev_of_node(dev: cpu_dev);
413
414 np = of_parse_phandle(np: cpu_np, phandle_name: "clocks", index: 0);
415 of_node_put(node: np);
416
417 if (np == scmi_np)
418 return true;
419
420 idx = of_property_match_string(np: cpu_np, propname: "power-domain-names", string: "perf");
421 np = of_parse_phandle(np: cpu_np, phandle_name: "power-domains", index: idx);
422 of_node_put(node: np);
423
424 if (np == scmi_np)
425 return true;
426 }
427
428 /*
429 * Older Broadcom STB chips had a "clocks" property for CPU node(s)
430 * that did not match the SCMI performance protocol node, if we got
431 * there, it means we had such an older Device Tree, therefore return
432 * true to preserve backwards compatibility.
433 */
434 if (of_machine_is_compatible(compat: "brcm,brcmstb"))
435 return true;
436
437 return false;
438}
439
440static int scmi_cpufreq_probe(struct scmi_device *sdev)
441{
442 int ret;
443 struct device *dev = &sdev->dev;
444 const struct scmi_handle *handle;
445
446 handle = sdev->handle;
447
448 if (!handle || !scmi_dev_used_by_cpus(scmi_dev: dev))
449 return -ENODEV;
450
451 scmi_cpufreq_driver.driver_data = sdev;
452
453 perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
454 if (IS_ERR(ptr: perf_ops))
455 return PTR_ERR(ptr: perf_ops);
456
457#ifdef CONFIG_COMMON_CLK
458 /* dummy clock provider as needed by OPP if clocks property is used */
459 if (of_property_present(np: dev->of_node, propname: "#clock-cells")) {
460 ret = devm_of_clk_add_hw_provider(dev, get: of_clk_hw_simple_get, NULL);
461 if (ret)
462 return dev_err_probe(dev, err: ret, fmt: "%s: registering clock provider failed\n", __func__);
463 }
464#endif
465
466 ret = cpufreq_register_driver(driver_data: &scmi_cpufreq_driver);
467 if (ret) {
468 dev_err(dev, "%s: registering cpufreq failed, err: %d\n",
469 __func__, ret);
470 }
471
472 return ret;
473}
474
475static void scmi_cpufreq_remove(struct scmi_device *sdev)
476{
477 cpufreq_unregister_driver(driver_data: &scmi_cpufreq_driver);
478}
479
480static const struct scmi_device_id scmi_id_table[] = {
481 { SCMI_PROTOCOL_PERF, "cpufreq" },
482 { },
483};
484MODULE_DEVICE_TABLE(scmi, scmi_id_table);
485
486static struct scmi_driver scmi_cpufreq_drv = {
487 .name = "scmi-cpufreq",
488 .probe = scmi_cpufreq_probe,
489 .remove = scmi_cpufreq_remove,
490 .id_table = scmi_id_table,
491};
492module_scmi_driver(scmi_cpufreq_drv);
493
494MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
495MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
496MODULE_LICENSE("GPL v2");
497

source code of linux/drivers/cpufreq/scmi-cpufreq.c