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
24struct scmi_data {
25	int domain_id;
26	int nr_opp;
27	struct device *cpu_dev;
28	cpumask_var_t opp_shared_cpus;
29};
30
31static struct scmi_protocol_handle *ph;
32static const struct scmi_perf_proto_ops *perf_ops;
33static struct cpufreq_driver scmi_cpufreq_driver;
34
35static 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 */
53static int
54scmi_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
62static 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
67	if (!perf_ops->freq_set(ph, priv->domain_id,
68				target_freq * 1000, true))
69		return target_freq;
70
71	return 0;
72}
73
74static 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
97static int
98scmi_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
120static int __maybe_unused
121scmi_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
148static int
149scmi_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
171static struct freq_attr *scmi_cpufreq_hw_attr[] = {
172	&cpufreq_freq_attr_scaling_available_freqs,
173	NULL,
174	NULL,
175};
176
177static 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
299out_free_opp:
300	dev_pm_opp_remove_all_dynamic(cpu_dev);
301
302out_free_cpumask:
303	free_cpumask_var(priv->opp_shared_cpus);
304
305out_free_priv:
306	kfree(priv);
307
308	return ret;
309}
310
311static int 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	return 0;
321}
322
323static void scmi_cpufreq_register_em(struct cpufreq_policy *policy)
324{
325	struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
326	enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph);
327	struct scmi_data *priv = policy->driver_data;
328	bool em_power_scale = false;
329
330	/*
331	 * This callback will be called for each policy, but we don't need to
332	 * register with EM every time. Despite not being part of the same
333	 * policy, some CPUs may still share their perf-domains, and a CPU from
334	 * another policy may already have registered with EM on behalf of CPUs
335	 * of this policy.
336	 */
337	if (!priv->nr_opp)
338		return;
339
340	if (power_scale == SCMI_POWER_MILLIWATTS
341	    || power_scale == SCMI_POWER_MICROWATTS)
342		em_power_scale = true;
343
344	em_dev_register_perf_domain(get_cpu_device(policy->cpu), priv->nr_opp,
345				    &em_cb, priv->opp_shared_cpus,
346				    em_power_scale);
347}
348
349static struct cpufreq_driver scmi_cpufreq_driver = {
350	.name	= "scmi",
351	.flags	= CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
352		  CPUFREQ_NEED_INITIAL_FREQ_CHECK |
353		  CPUFREQ_IS_COOLING_DEV,
354	.verify	= cpufreq_generic_frequency_table_verify,
355	.attr	= scmi_cpufreq_hw_attr,
356	.target_index	= scmi_cpufreq_set_target,
357	.fast_switch	= scmi_cpufreq_fast_switch,
358	.get	= scmi_cpufreq_get_rate,
359	.init	= scmi_cpufreq_init,
360	.exit	= scmi_cpufreq_exit,
361	.register_em	= scmi_cpufreq_register_em,
362};
363
364static int scmi_cpufreq_probe(struct scmi_device *sdev)
365{
366	int ret;
367	struct device *dev = &sdev->dev;
368	const struct scmi_handle *handle;
369
370	handle = sdev->handle;
371
372	if (!handle)
373		return -ENODEV;
374
375	perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
376	if (IS_ERR(perf_ops))
377		return PTR_ERR(perf_ops);
378
379#ifdef CONFIG_COMMON_CLK
380	/* dummy clock provider as needed by OPP if clocks property is used */
381	if (of_property_present(dev->of_node, "#clock-cells")) {
382		ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, NULL);
383		if (ret)
384			return dev_err_probe(dev, ret, "%s: registering clock provider failed\n", __func__);
385	}
386#endif
387
388	ret = cpufreq_register_driver(&scmi_cpufreq_driver);
389	if (ret) {
390		dev_err(dev, "%s: registering cpufreq failed, err: %d\n",
391			__func__, ret);
392	}
393
394	return ret;
395}
396
397static void scmi_cpufreq_remove(struct scmi_device *sdev)
398{
399	cpufreq_unregister_driver(&scmi_cpufreq_driver);
400}
401
402static const struct scmi_device_id scmi_id_table[] = {
403	{ SCMI_PROTOCOL_PERF, "cpufreq" },
404	{ },
405};
406MODULE_DEVICE_TABLE(scmi, scmi_id_table);
407
408static struct scmi_driver scmi_cpufreq_drv = {
409	.name		= "scmi-cpufreq",
410	.probe		= scmi_cpufreq_probe,
411	.remove		= scmi_cpufreq_remove,
412	.id_table	= scmi_id_table,
413};
414module_scmi_driver(scmi_cpufreq_drv);
415
416MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
417MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
418MODULE_LICENSE("GPL v2");
419