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
scmi_cpufreq_get_rate(unsigned int cpu)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
scmi_cpufreq_set_target(struct cpufreq_policy * policy,unsigned int index)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
scmi_cpufreq_fast_switch(struct cpufreq_policy * policy,unsigned int target_freq)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
scmi_get_sharing_cpus(struct device * cpu_dev,struct cpumask * cpumask)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
scmi_get_cpu_power(struct device * cpu_dev,unsigned long * power,unsigned long * KHz)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
scmi_cpufreq_init(struct cpufreq_policy * policy)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
scmi_cpufreq_exit(struct cpufreq_policy * policy)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
scmi_cpufreq_register_em(struct cpufreq_policy * policy)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
scmi_cpufreq_probe(struct scmi_device * sdev)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
scmi_cpufreq_remove(struct scmi_device * sdev)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