scmi-cpufreq.c

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