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 
23 struct scmi_data {
24 	int domain_id;
25 	int nr_opp;
26 	struct device *cpu_dev;
27 	cpumask_var_t opp_shared_cpus;
28 };
29 
30 static struct scmi_protocol_handle *ph;
31 static const struct scmi_perf_proto_ops *perf_ops;
32 
33 static unsigned int scmi_cpufreq_get_rate(unsigned int cpu)
34 {
35 	struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
36 	struct scmi_data *priv = policy->driver_data;
37 	unsigned long rate;
38 	int ret;
39 
40 	ret = perf_ops->freq_get(ph, priv->domain_id, &rate, false);
41 	if (ret)
42 		return 0;
43 	return rate / 1000;
44 }
45 
46 /*
47  * perf_ops->freq_set is not a synchronous, the actual OPP change will
48  * happen asynchronously and can get notified if the events are
49  * subscribed for by the SCMI firmware
50  */
51 static int
52 scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
53 {
54 	struct scmi_data *priv = policy->driver_data;
55 	u64 freq = policy->freq_table[index].frequency;
56 
57 	return perf_ops->freq_set(ph, priv->domain_id, freq * 1000, false);
58 }
59 
60 static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy,
61 					     unsigned int target_freq)
62 {
63 	struct scmi_data *priv = policy->driver_data;
64 
65 	if (!perf_ops->freq_set(ph, priv->domain_id,
66 				target_freq * 1000, true))
67 		return target_freq;
68 
69 	return 0;
70 }
71 
72 static int
73 scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
74 {
75 	int cpu, domain, tdomain;
76 	struct device *tcpu_dev;
77 
78 	domain = perf_ops->device_domain_id(cpu_dev);
79 	if (domain < 0)
80 		return domain;
81 
82 	for_each_possible_cpu(cpu) {
83 		if (cpu == cpu_dev->id)
84 			continue;
85 
86 		tcpu_dev = get_cpu_device(cpu);
87 		if (!tcpu_dev)
88 			continue;
89 
90 		tdomain = perf_ops->device_domain_id(tcpu_dev);
91 		if (tdomain == domain)
92 			cpumask_set_cpu(cpu, cpumask);
93 	}
94 
95 	return 0;
96 }
97 
98 static int __maybe_unused
99 scmi_get_cpu_power(unsigned long *power, unsigned long *KHz,
100 		   struct device *cpu_dev)
101 {
102 	unsigned long Hz;
103 	int ret, domain;
104 
105 	domain = perf_ops->device_domain_id(cpu_dev);
106 	if (domain < 0)
107 		return domain;
108 
109 	/* Get the power cost of the performance domain. */
110 	Hz = *KHz * 1000;
111 	ret = perf_ops->est_power_get(ph, domain, &Hz, power);
112 	if (ret)
113 		return ret;
114 
115 	/* The EM framework specifies the frequency in KHz. */
116 	*KHz = Hz / 1000;
117 
118 	return 0;
119 }
120 
121 static int scmi_cpufreq_init(struct cpufreq_policy *policy)
122 {
123 	int ret, nr_opp;
124 	unsigned int latency;
125 	struct device *cpu_dev;
126 	struct scmi_data *priv;
127 	struct cpufreq_frequency_table *freq_table;
128 
129 	cpu_dev = get_cpu_device(policy->cpu);
130 	if (!cpu_dev) {
131 		pr_err("failed to get cpu%d device\n", policy->cpu);
132 		return -ENODEV;
133 	}
134 
135 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
136 	if (!priv)
137 		return -ENOMEM;
138 
139 	if (!zalloc_cpumask_var(&priv->opp_shared_cpus, GFP_KERNEL)) {
140 		ret = -ENOMEM;
141 		goto out_free_priv;
142 	}
143 
144 	/* Obtain CPUs that share SCMI performance controls */
145 	ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus);
146 	if (ret) {
147 		dev_warn(cpu_dev, "failed to get sharing cpumask\n");
148 		goto out_free_cpumask;
149 	}
150 
151 	/*
152 	 * Obtain CPUs that share performance levels.
153 	 * The OPP 'sharing cpus' info may come from DT through an empty opp
154 	 * table and opp-shared.
155 	 */
156 	ret = dev_pm_opp_of_get_sharing_cpus(cpu_dev, priv->opp_shared_cpus);
157 	if (ret || !cpumask_weight(priv->opp_shared_cpus)) {
158 		/*
159 		 * Either opp-table is not set or no opp-shared was found.
160 		 * Use the CPU mask from SCMI to designate CPUs sharing an OPP
161 		 * table.
162 		 */
163 		cpumask_copy(priv->opp_shared_cpus, policy->cpus);
164 	}
165 
166 	 /*
167 	  * A previous CPU may have marked OPPs as shared for a few CPUs, based on
168 	  * what OPP core provided. If the current CPU is part of those few, then
169 	  * there is no need to add OPPs again.
170 	  */
171 	nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
172 	if (nr_opp <= 0) {
173 		ret = perf_ops->device_opps_add(ph, cpu_dev);
174 		if (ret) {
175 			dev_warn(cpu_dev, "failed to add opps to the device\n");
176 			goto out_free_cpumask;
177 		}
178 
179 		nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
180 		if (nr_opp <= 0) {
181 			dev_err(cpu_dev, "%s: No OPPs for this device: %d\n",
182 				__func__, nr_opp);
183 
184 			ret = -ENODEV;
185 			goto out_free_opp;
186 		}
187 
188 		ret = dev_pm_opp_set_sharing_cpus(cpu_dev, priv->opp_shared_cpus);
189 		if (ret) {
190 			dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
191 				__func__, ret);
192 
193 			goto out_free_opp;
194 		}
195 
196 		priv->nr_opp = nr_opp;
197 	}
198 
199 	ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
200 	if (ret) {
201 		dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
202 		goto out_free_opp;
203 	}
204 
205 	priv->cpu_dev = cpu_dev;
206 	priv->domain_id = perf_ops->device_domain_id(cpu_dev);
207 
208 	policy->driver_data = priv;
209 	policy->freq_table = freq_table;
210 
211 	/* SCMI allows DVFS request for any domain from any CPU */
212 	policy->dvfs_possible_from_any_cpu = true;
213 
214 	latency = perf_ops->transition_latency_get(ph, cpu_dev);
215 	if (!latency)
216 		latency = CPUFREQ_ETERNAL;
217 
218 	policy->cpuinfo.transition_latency = latency;
219 
220 	policy->fast_switch_possible =
221 		perf_ops->fast_switch_possible(ph, cpu_dev);
222 
223 	return 0;
224 
225 out_free_opp:
226 	dev_pm_opp_remove_all_dynamic(cpu_dev);
227 
228 out_free_cpumask:
229 	free_cpumask_var(priv->opp_shared_cpus);
230 
231 out_free_priv:
232 	kfree(priv);
233 
234 	return ret;
235 }
236 
237 static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
238 {
239 	struct scmi_data *priv = policy->driver_data;
240 
241 	dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
242 	dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
243 	free_cpumask_var(priv->opp_shared_cpus);
244 	kfree(priv);
245 
246 	return 0;
247 }
248 
249 static void scmi_cpufreq_register_em(struct cpufreq_policy *policy)
250 {
251 	struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
252 	bool power_scale_mw = perf_ops->power_scale_mw_get(ph);
253 	struct scmi_data *priv = policy->driver_data;
254 
255 	/*
256 	 * This callback will be called for each policy, but we don't need to
257 	 * register with EM every time. Despite not being part of the same
258 	 * policy, some CPUs may still share their perf-domains, and a CPU from
259 	 * another policy may already have registered with EM on behalf of CPUs
260 	 * of this policy.
261 	 */
262 	if (!priv->nr_opp)
263 		return;
264 
265 	em_dev_register_perf_domain(get_cpu_device(policy->cpu), priv->nr_opp,
266 				    &em_cb, priv->opp_shared_cpus,
267 				    power_scale_mw);
268 }
269 
270 static struct cpufreq_driver scmi_cpufreq_driver = {
271 	.name	= "scmi",
272 	.flags	= CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
273 		  CPUFREQ_NEED_INITIAL_FREQ_CHECK |
274 		  CPUFREQ_IS_COOLING_DEV,
275 	.verify	= cpufreq_generic_frequency_table_verify,
276 	.attr	= cpufreq_generic_attr,
277 	.target_index	= scmi_cpufreq_set_target,
278 	.fast_switch	= scmi_cpufreq_fast_switch,
279 	.get	= scmi_cpufreq_get_rate,
280 	.init	= scmi_cpufreq_init,
281 	.exit	= scmi_cpufreq_exit,
282 	.register_em	= scmi_cpufreq_register_em,
283 };
284 
285 static int scmi_cpufreq_probe(struct scmi_device *sdev)
286 {
287 	int ret;
288 	struct device *dev = &sdev->dev;
289 	const struct scmi_handle *handle;
290 
291 	handle = sdev->handle;
292 
293 	if (!handle)
294 		return -ENODEV;
295 
296 	perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
297 	if (IS_ERR(perf_ops))
298 		return PTR_ERR(perf_ops);
299 
300 #ifdef CONFIG_COMMON_CLK
301 	/* dummy clock provider as needed by OPP if clocks property is used */
302 	if (of_find_property(dev->of_node, "#clock-cells", NULL))
303 		devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, NULL);
304 #endif
305 
306 	ret = cpufreq_register_driver(&scmi_cpufreq_driver);
307 	if (ret) {
308 		dev_err(dev, "%s: registering cpufreq failed, err: %d\n",
309 			__func__, ret);
310 	}
311 
312 	return ret;
313 }
314 
315 static void scmi_cpufreq_remove(struct scmi_device *sdev)
316 {
317 	cpufreq_unregister_driver(&scmi_cpufreq_driver);
318 }
319 
320 static const struct scmi_device_id scmi_id_table[] = {
321 	{ SCMI_PROTOCOL_PERF, "cpufreq" },
322 	{ },
323 };
324 MODULE_DEVICE_TABLE(scmi, scmi_id_table);
325 
326 static struct scmi_driver scmi_cpufreq_drv = {
327 	.name		= "scmi-cpufreq",
328 	.probe		= scmi_cpufreq_probe,
329 	.remove		= scmi_cpufreq_remove,
330 	.id_table	= scmi_id_table,
331 };
332 module_scmi_driver(scmi_cpufreq_drv);
333 
334 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
335 MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
336 MODULE_LICENSE("GPL v2");
337