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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/drivers/devfreq/governor_passive.c
4 *
5 * Copyright (C) 2016 Samsung Electronics
6 * Author: Chanwoo Choi <[email protected]>
7 * Author: MyungJoo Ham <[email protected]>
8 */
9
10#include <linux/module.h>
11#include <linux/cpu.h>
12#include <linux/cpufreq.h>
13#include <linux/cpumask.h>
14#include <linux/slab.h>
15#include <linux/device.h>
16#include <linux/devfreq.h>
17#include <linux/devfreq-governor.h>
18#include <linux/units.h>
19
20/**
21 * struct devfreq_cpu_data - Hold the per-cpu data
22 * @node: list node
23 * @dev: reference to cpu device.
24 * @first_cpu: the cpumask of the first cpu of a policy.
25 * @opp_table: reference to cpu opp table.
26 * @cur_freq: the current frequency of the cpu.
27 * @min_freq: the min frequency of the cpu.
28 * @max_freq: the max frequency of the cpu.
29 *
30 * This structure stores the required cpu_data of a cpu.
31 * This is auto-populated by the governor.
32 */
33struct devfreq_cpu_data {
34 struct list_head node;
35
36 struct device *dev;
37 unsigned int first_cpu;
38
39 struct opp_table *opp_table;
40 unsigned int cur_freq;
41 unsigned int min_freq;
42 unsigned int max_freq;
43};
44
45static struct devfreq_cpu_data *
46get_parent_cpu_data(struct devfreq_passive_data *p_data,
47 struct cpufreq_policy *policy)
48{
49 struct devfreq_cpu_data *parent_cpu_data;
50
51 if (!p_data || !policy)
52 return NULL;
53
54 list_for_each_entry(parent_cpu_data, &p_data->cpu_data_list, node)
55 if (parent_cpu_data->first_cpu == cpumask_first(policy->related_cpus))
56 return parent_cpu_data;
57
58 return NULL;
59}
60
61static void delete_parent_cpu_data(struct devfreq_passive_data *p_data)
62{
63 struct devfreq_cpu_data *parent_cpu_data, *tmp;
64
65 list_for_each_entry_safe(parent_cpu_data, tmp, &p_data->cpu_data_list, node) {
66 list_del(&parent_cpu_data->node);
67
68 if (parent_cpu_data->opp_table)
69 dev_pm_opp_put_opp_table(parent_cpu_data->opp_table);
70
71 kfree(parent_cpu_data);
72 }
73}
74
75static unsigned long get_target_freq_by_required_opp(struct device *p_dev,
76 struct opp_table *p_opp_table,
77 struct opp_table *opp_table,
78 unsigned long *freq)
79{
80 struct dev_pm_opp *opp = NULL, *p_opp = NULL;
81 unsigned long target_freq;
82
83 if (!p_dev || !p_opp_table || !opp_table || !freq)
84 return 0;
85
86 p_opp = devfreq_recommended_opp(p_dev, freq, 0);
87 if (IS_ERR(p_opp))
88 return 0;
89
90 opp = dev_pm_opp_xlate_required_opp(p_opp_table, opp_table, p_opp);
91 dev_pm_opp_put(p_opp);
92
93 if (IS_ERR(opp))
94 return 0;
95
96 target_freq = dev_pm_opp_get_freq(opp);
97 dev_pm_opp_put(opp);
98
99 return target_freq;
100}
101
102static int get_target_freq_with_cpufreq(struct devfreq *devfreq,
103 unsigned long *target_freq)
104{
105 struct devfreq_passive_data *p_data =
106 (struct devfreq_passive_data *)devfreq->data;
107 struct devfreq_cpu_data *parent_cpu_data;
108 struct cpufreq_policy *policy;
109 unsigned long cpu, cpu_cur, cpu_min, cpu_max, cpu_percent;
110 unsigned long dev_min, dev_max;
111 unsigned long freq = 0;
112 int ret = 0;
113
114 for_each_online_cpu(cpu) {
115 policy = cpufreq_cpu_get(cpu);
116 if (!policy) {
117 ret = -EINVAL;
118 continue;
119 }
120
121 parent_cpu_data = get_parent_cpu_data(p_data, policy);
122 if (!parent_cpu_data) {
123 cpufreq_cpu_put(policy);
124 continue;
125 }
126
127 /* Get target freq via required opps */
128 cpu_cur = parent_cpu_data->cur_freq * HZ_PER_KHZ;
129 freq = get_target_freq_by_required_opp(parent_cpu_data->dev,
130 parent_cpu_data->opp_table,
131 devfreq->opp_table, &cpu_cur);
132 if (freq) {
133 *target_freq = max(freq, *target_freq);
134 cpufreq_cpu_put(policy);
135 continue;
136 }
137
138 /* Use interpolation if required opps is not available */
139 devfreq_get_freq_range(devfreq, &dev_min, &dev_max);
140
141 cpu_min = parent_cpu_data->min_freq;
142 cpu_max = parent_cpu_data->max_freq;
143 cpu_cur = parent_cpu_data->cur_freq;
144
145 cpu_percent = ((cpu_cur - cpu_min) * 100) / (cpu_max - cpu_min);
146 freq = dev_min + mult_frac(dev_max - dev_min, cpu_percent, 100);
147
148 *target_freq = max(freq, *target_freq);
149 cpufreq_cpu_put(policy);
150 }
151
152 return ret;
153}
154
155static int get_target_freq_with_devfreq(struct devfreq *devfreq,
156 unsigned long *freq)
157{
158 struct devfreq_passive_data *p_data
159 = (struct devfreq_passive_data *)devfreq->data;
160 struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent;
161 unsigned long child_freq = ULONG_MAX;
162 int i, count;
163
164 /* Get target freq via required opps */
165 child_freq = get_target_freq_by_required_opp(parent_devfreq->dev.parent,
166 parent_devfreq->opp_table,
167 devfreq->opp_table, freq);
168 if (child_freq)
169 goto out;
170
171 /* Use interpolation if required opps is not available */
172 for (i = 0; i < parent_devfreq->max_state; i++)
173 if (parent_devfreq->freq_table[i] == *freq)
174 break;
175
176 if (i == parent_devfreq->max_state)
177 return -EINVAL;
178
179 if (i < devfreq->max_state) {
180 child_freq = devfreq->freq_table[i];
181 } else {
182 count = devfreq->max_state;
183 child_freq = devfreq->freq_table[count - 1];
184 }
185
186out:
187 *freq = child_freq;
188
189 return 0;
190}
191
192static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
193 unsigned long *freq)
194{
195 struct devfreq_passive_data *p_data =
196 (struct devfreq_passive_data *)devfreq->data;
197 int ret;
198
199 if (!p_data)
200 return -EINVAL;
201
202 /*
203 * If the devfreq device with passive governor has the specific method
204 * to determine the next frequency, should use the get_target_freq()
205 * of struct devfreq_passive_data.
206 */
207 if (p_data->get_target_freq)
208 return p_data->get_target_freq(devfreq, freq);
209
210 switch (p_data->parent_type) {
211 case DEVFREQ_PARENT_DEV:
212 ret = get_target_freq_with_devfreq(devfreq, freq);
213 break;
214 case CPUFREQ_PARENT_DEV:
215 ret = get_target_freq_with_cpufreq(devfreq, freq);
216 break;
217 default:
218 ret = -EINVAL;
219 dev_err(&devfreq->dev, "Invalid parent type\n");
220 break;
221 }
222
223 return ret;
224}
225
226static int cpufreq_passive_notifier_call(struct notifier_block *nb,
227 unsigned long event, void *ptr)
228{
229 struct devfreq_passive_data *p_data =
230 container_of(nb, struct devfreq_passive_data, nb);
231 struct devfreq *devfreq = (struct devfreq *)p_data->this;
232 struct devfreq_cpu_data *parent_cpu_data;
233 struct cpufreq_freqs *freqs = ptr;
234 unsigned int cur_freq;
235 int ret;
236
237 if (event != CPUFREQ_POSTCHANGE || !freqs)
238 return 0;
239
240 parent_cpu_data = get_parent_cpu_data(p_data, freqs->policy);
241 if (!parent_cpu_data || parent_cpu_data->cur_freq == freqs->new)
242 return 0;
243
244 cur_freq = parent_cpu_data->cur_freq;
245 parent_cpu_data->cur_freq = freqs->new;
246
247 mutex_lock(&devfreq->lock);
248 ret = devfreq_update_target(devfreq, freqs->new);
249 mutex_unlock(&devfreq->lock);
250 if (ret) {
251 parent_cpu_data->cur_freq = cur_freq;
252 dev_err(&devfreq->dev, "failed to update the frequency.\n");
253 return ret;
254 }
255
256 return 0;
257}
258
259static int cpufreq_passive_unregister_notifier(struct devfreq *devfreq)
260{
261 struct devfreq_passive_data *p_data
262 = (struct devfreq_passive_data *)devfreq->data;
263 int ret;
264
265 if (p_data->nb.notifier_call) {
266 ret = cpufreq_unregister_notifier(&p_data->nb,
267 CPUFREQ_TRANSITION_NOTIFIER);
268 if (ret < 0)
269 return ret;
270 }
271
272 delete_parent_cpu_data(p_data);
273
274 return 0;
275}
276
277static int cpufreq_passive_register_notifier(struct devfreq *devfreq)
278{
279 struct devfreq_passive_data *p_data
280 = (struct devfreq_passive_data *)devfreq->data;
281 struct device *dev = devfreq->dev.parent;
282 struct opp_table *opp_table = NULL;
283 struct devfreq_cpu_data *parent_cpu_data;
284 struct cpufreq_policy *policy;
285 struct device *cpu_dev;
286 unsigned int cpu;
287 int ret;
288
289 p_data->cpu_data_list
290 = (struct list_head)LIST_HEAD_INIT(p_data->cpu_data_list);
291
292 p_data->nb.notifier_call = cpufreq_passive_notifier_call;
293 ret = cpufreq_register_notifier(&p_data->nb, CPUFREQ_TRANSITION_NOTIFIER);
294 if (ret) {
295 dev_err(dev, "failed to register cpufreq notifier\n");
296 p_data->nb.notifier_call = NULL;
297 goto err;
298 }
299
300 for_each_possible_cpu(cpu) {
301 policy = cpufreq_cpu_get(cpu);
302 if (!policy) {
303 ret = -EPROBE_DEFER;
304 goto err;
305 }
306
307 parent_cpu_data = get_parent_cpu_data(p_data, policy);
308 if (parent_cpu_data) {
309 cpufreq_cpu_put(policy);
310 continue;
311 }
312
313 parent_cpu_data = kzalloc_obj(*parent_cpu_data);
314 if (!parent_cpu_data) {
315 ret = -ENOMEM;
316 goto err_put_policy;
317 }
318
319 cpu_dev = get_cpu_device(cpu);
320 if (!cpu_dev) {
321 dev_err(dev, "failed to get cpu device\n");
322 ret = -ENODEV;
323 goto err_free_cpu_data;
324 }
325
326 opp_table = dev_pm_opp_get_opp_table(cpu_dev);
327 if (IS_ERR(opp_table)) {
328 dev_err(dev, "failed to get opp_table of cpu%d\n", cpu);
329 ret = PTR_ERR(opp_table);
330 goto err_free_cpu_data;
331 }
332
333 parent_cpu_data->dev = cpu_dev;
334 parent_cpu_data->opp_table = opp_table;
335 parent_cpu_data->first_cpu = cpumask_first(policy->related_cpus);
336 parent_cpu_data->cur_freq = policy->cur;
337 parent_cpu_data->min_freq = policy->cpuinfo.min_freq;
338 parent_cpu_data->max_freq = policy->cpuinfo.max_freq;
339
340 list_add_tail(&parent_cpu_data->node, &p_data->cpu_data_list);
341 cpufreq_cpu_put(policy);
342 }
343
344 mutex_lock(&devfreq->lock);
345 ret = devfreq_update_target(devfreq, 0L);
346 mutex_unlock(&devfreq->lock);
347 if (ret)
348 dev_err(dev, "failed to update the frequency\n");
349
350 return ret;
351
352err_free_cpu_data:
353 kfree(parent_cpu_data);
354err_put_policy:
355 cpufreq_cpu_put(policy);
356err:
357
358 return ret;
359}
360
361static int devfreq_passive_notifier_call(struct notifier_block *nb,
362 unsigned long event, void *ptr)
363{
364 struct devfreq_passive_data *data
365 = container_of(nb, struct devfreq_passive_data, nb);
366 struct devfreq *devfreq = (struct devfreq *)data->this;
367 struct devfreq *parent = (struct devfreq *)data->parent;
368 struct devfreq_freqs *freqs = (struct devfreq_freqs *)ptr;
369 unsigned long freq = freqs->new;
370 int ret = 0;
371
372 mutex_lock_nested(&devfreq->lock, SINGLE_DEPTH_NESTING);
373 switch (event) {
374 case DEVFREQ_PRECHANGE:
375 if (parent->previous_freq > freq)
376 ret = devfreq_update_target(devfreq, freq);
377
378 break;
379 case DEVFREQ_POSTCHANGE:
380 if (parent->previous_freq < freq)
381 ret = devfreq_update_target(devfreq, freq);
382 break;
383 }
384 mutex_unlock(&devfreq->lock);
385
386 if (ret < 0)
387 dev_warn(&devfreq->dev,
388 "failed to update devfreq using passive governor\n");
389
390 return NOTIFY_DONE;
391}
392
393static int devfreq_passive_unregister_notifier(struct devfreq *devfreq)
394{
395 struct devfreq_passive_data *p_data
396 = (struct devfreq_passive_data *)devfreq->data;
397 struct devfreq *parent = (struct devfreq *)p_data->parent;
398 struct notifier_block *nb = &p_data->nb;
399
400 return devfreq_unregister_notifier(parent, nb, DEVFREQ_TRANSITION_NOTIFIER);
401}
402
403static int devfreq_passive_register_notifier(struct devfreq *devfreq)
404{
405 struct devfreq_passive_data *p_data
406 = (struct devfreq_passive_data *)devfreq->data;
407 struct devfreq *parent = (struct devfreq *)p_data->parent;
408 struct notifier_block *nb = &p_data->nb;
409
410 if (!parent)
411 return -EPROBE_DEFER;
412
413 nb->notifier_call = devfreq_passive_notifier_call;
414 return devfreq_register_notifier(parent, nb, DEVFREQ_TRANSITION_NOTIFIER);
415}
416
417static int devfreq_passive_event_handler(struct devfreq *devfreq,
418 unsigned int event, void *data)
419{
420 struct devfreq_passive_data *p_data
421 = (struct devfreq_passive_data *)devfreq->data;
422 int ret = 0;
423
424 if (!p_data)
425 return -EINVAL;
426
427 p_data->this = devfreq;
428
429 switch (event) {
430 case DEVFREQ_GOV_START:
431 if (p_data->parent_type == DEVFREQ_PARENT_DEV)
432 ret = devfreq_passive_register_notifier(devfreq);
433 else if (p_data->parent_type == CPUFREQ_PARENT_DEV)
434 ret = cpufreq_passive_register_notifier(devfreq);
435 break;
436 case DEVFREQ_GOV_STOP:
437 if (p_data->parent_type == DEVFREQ_PARENT_DEV)
438 WARN_ON(devfreq_passive_unregister_notifier(devfreq));
439 else if (p_data->parent_type == CPUFREQ_PARENT_DEV)
440 WARN_ON(cpufreq_passive_unregister_notifier(devfreq));
441 break;
442 default:
443 break;
444 }
445
446 return ret;
447}
448
449static struct devfreq_governor devfreq_passive = {
450 .name = DEVFREQ_GOV_PASSIVE,
451 .flags = DEVFREQ_GOV_FLAG_IMMUTABLE,
452 .get_target_freq = devfreq_passive_get_target_freq,
453 .event_handler = devfreq_passive_event_handler,
454};
455
456static int __init devfreq_passive_init(void)
457{
458 return devfreq_add_governor(&devfreq_passive);
459}
460subsys_initcall(devfreq_passive_init);
461
462static void __exit devfreq_passive_exit(void)
463{
464 int ret;
465
466 ret = devfreq_remove_governor(&devfreq_passive);
467 if (ret)
468 pr_err("%s: failed remove governor %d\n", __func__, ret);
469}
470module_exit(devfreq_passive_exit);
471
472MODULE_AUTHOR("Chanwoo Choi <[email protected]>");
473MODULE_AUTHOR("MyungJoo Ham <[email protected]>");
474MODULE_DESCRIPTION("DEVFREQ Passive governor");
475MODULE_LICENSE("GPL v2");