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