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