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