1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * devfreq_cooling: Thermal cooling device implementation for devices using
4  *                  devfreq
5  *
6  * Copyright (C) 2014-2015 ARM Limited
7  *
8  * TODO:
9  *    - If OPPs are added or removed after devfreq cooling has
10  *      registered, the devfreq cooling won't react to it.
11  */
12 
13 #include <linux/devfreq.h>
14 #include <linux/devfreq_cooling.h>
15 #include <linux/energy_model.h>
16 #include <linux/export.h>
17 #include <linux/slab.h>
18 #include <linux/pm_opp.h>
19 #include <linux/pm_qos.h>
20 #include <linux/thermal.h>
21 #include <linux/units.h>
22 
23 #include <trace/events/thermal.h>
24 
25 #define SCALE_ERROR_MITIGATION	100
26 
27 /**
28  * struct devfreq_cooling_device - Devfreq cooling device
29  *		devfreq_cooling_device registered.
30  * @cdev:	Pointer to associated thermal cooling device.
31  * @devfreq:	Pointer to associated devfreq device.
32  * @cooling_state:	Current cooling state.
33  * @freq_table:	Pointer to a table with the frequencies sorted in descending
34  *		order.  You can index the table by cooling device state
35  * @max_state:	It is the last index, that is, one less than the number of the
36  *		OPPs
37  * @power_ops:	Pointer to devfreq_cooling_power, a more precised model.
38  * @res_util:	Resource utilization scaling factor for the power.
39  *		It is multiplied by 100 to minimize the error. It is used
40  *		for estimation of the power budget instead of using
41  *		'utilization' (which is	'busy_time' / 'total_time').
42  *		The 'res_util' range is from 100 to power * 100	for the
43  *		corresponding 'state'.
44  * @capped_state:	index to cooling state with in dynamic power budget
45  * @req_max_freq:	PM QoS request for limiting the maximum frequency
46  *			of the devfreq device.
47  * @em_pd:		Energy Model for the associated Devfreq device
48  */
49 struct devfreq_cooling_device {
50 	struct thermal_cooling_device *cdev;
51 	struct devfreq *devfreq;
52 	unsigned long cooling_state;
53 	u32 *freq_table;
54 	size_t max_state;
55 	struct devfreq_cooling_power *power_ops;
56 	u32 res_util;
57 	int capped_state;
58 	struct dev_pm_qos_request req_max_freq;
59 	struct em_perf_domain *em_pd;
60 };
61 
62 static int devfreq_cooling_get_max_state(struct thermal_cooling_device *cdev,
63 					 unsigned long *state)
64 {
65 	struct devfreq_cooling_device *dfc = cdev->devdata;
66 
67 	*state = dfc->max_state;
68 
69 	return 0;
70 }
71 
72 static int devfreq_cooling_get_cur_state(struct thermal_cooling_device *cdev,
73 					 unsigned long *state)
74 {
75 	struct devfreq_cooling_device *dfc = cdev->devdata;
76 
77 	*state = dfc->cooling_state;
78 
79 	return 0;
80 }
81 
82 static int devfreq_cooling_set_cur_state(struct thermal_cooling_device *cdev,
83 					 unsigned long state)
84 {
85 	struct devfreq_cooling_device *dfc = cdev->devdata;
86 	struct devfreq *df = dfc->devfreq;
87 	struct device *dev = df->dev.parent;
88 	unsigned long freq;
89 	int perf_idx;
90 
91 	if (state == dfc->cooling_state)
92 		return 0;
93 
94 	dev_dbg(dev, "Setting cooling state %lu\n", state);
95 
96 	if (state > dfc->max_state)
97 		return -EINVAL;
98 
99 	if (dfc->em_pd) {
100 		perf_idx = dfc->max_state - state;
101 		freq = dfc->em_pd->table[perf_idx].frequency * 1000;
102 	} else {
103 		freq = dfc->freq_table[state];
104 	}
105 
106 	dev_pm_qos_update_request(&dfc->req_max_freq,
107 				  DIV_ROUND_UP(freq, HZ_PER_KHZ));
108 
109 	dfc->cooling_state = state;
110 
111 	return 0;
112 }
113 
114 /**
115  * get_perf_idx() - get the performance index corresponding to a frequency
116  * @em_pd:	Pointer to device's Energy Model
117  * @freq:	frequency in kHz
118  *
119  * Return: the performance index associated with the @freq, or
120  * -EINVAL if it wasn't found.
121  */
122 static int get_perf_idx(struct em_perf_domain *em_pd, unsigned long freq)
123 {
124 	int i;
125 
126 	for (i = 0; i < em_pd->nr_perf_states; i++) {
127 		if (em_pd->table[i].frequency == freq)
128 			return i;
129 	}
130 
131 	return -EINVAL;
132 }
133 
134 static unsigned long get_voltage(struct devfreq *df, unsigned long freq)
135 {
136 	struct device *dev = df->dev.parent;
137 	unsigned long voltage;
138 	struct dev_pm_opp *opp;
139 
140 	opp = dev_pm_opp_find_freq_exact(dev, freq, true);
141 	if (PTR_ERR(opp) == -ERANGE)
142 		opp = dev_pm_opp_find_freq_exact(dev, freq, false);
143 
144 	if (IS_ERR(opp)) {
145 		dev_err_ratelimited(dev, "Failed to find OPP for frequency %lu: %ld\n",
146 				    freq, PTR_ERR(opp));
147 		return 0;
148 	}
149 
150 	voltage = dev_pm_opp_get_voltage(opp) / 1000; /* mV */
151 	dev_pm_opp_put(opp);
152 
153 	if (voltage == 0) {
154 		dev_err_ratelimited(dev,
155 				    "Failed to get voltage for frequency %lu\n",
156 				    freq);
157 	}
158 
159 	return voltage;
160 }
161 
162 static void _normalize_load(struct devfreq_dev_status *status)
163 {
164 	if (status->total_time > 0xfffff) {
165 		status->total_time >>= 10;
166 		status->busy_time >>= 10;
167 	}
168 
169 	status->busy_time <<= 10;
170 	status->busy_time /= status->total_time ? : 1;
171 
172 	status->busy_time = status->busy_time ? : 1;
173 	status->total_time = 1024;
174 }
175 
176 static int devfreq_cooling_get_requested_power(struct thermal_cooling_device *cdev,
177 					       u32 *power)
178 {
179 	struct devfreq_cooling_device *dfc = cdev->devdata;
180 	struct devfreq *df = dfc->devfreq;
181 	struct devfreq_dev_status status;
182 	unsigned long state;
183 	unsigned long freq;
184 	unsigned long voltage;
185 	int res, perf_idx;
186 
187 	mutex_lock(&df->lock);
188 	status = df->last_status;
189 	mutex_unlock(&df->lock);
190 
191 	freq = status.current_frequency;
192 
193 	if (dfc->power_ops && dfc->power_ops->get_real_power) {
194 		voltage = get_voltage(df, freq);
195 		if (voltage == 0) {
196 			res = -EINVAL;
197 			goto fail;
198 		}
199 
200 		res = dfc->power_ops->get_real_power(df, power, freq, voltage);
201 		if (!res) {
202 			state = dfc->capped_state;
203 			dfc->res_util = dfc->em_pd->table[state].power;
204 			dfc->res_util *= SCALE_ERROR_MITIGATION;
205 
206 			if (*power > 1)
207 				dfc->res_util /= *power;
208 		} else {
209 			goto fail;
210 		}
211 	} else {
212 		/* Energy Model frequencies are in kHz */
213 		perf_idx = get_perf_idx(dfc->em_pd, freq / 1000);
214 		if (perf_idx < 0) {
215 			res = -EAGAIN;
216 			goto fail;
217 		}
218 
219 		_normalize_load(&status);
220 
221 		/* Scale power for utilization */
222 		*power = dfc->em_pd->table[perf_idx].power;
223 		*power *= status.busy_time;
224 		*power >>= 10;
225 	}
226 
227 	trace_thermal_power_devfreq_get_power(cdev, &status, freq, *power);
228 
229 	return 0;
230 fail:
231 	/* It is safe to set max in this case */
232 	dfc->res_util = SCALE_ERROR_MITIGATION;
233 	return res;
234 }
235 
236 static int devfreq_cooling_state2power(struct thermal_cooling_device *cdev,
237 				       unsigned long state, u32 *power)
238 {
239 	struct devfreq_cooling_device *dfc = cdev->devdata;
240 	int perf_idx;
241 
242 	if (state > dfc->max_state)
243 		return -EINVAL;
244 
245 	perf_idx = dfc->max_state - state;
246 	*power = dfc->em_pd->table[perf_idx].power;
247 
248 	return 0;
249 }
250 
251 static int devfreq_cooling_power2state(struct thermal_cooling_device *cdev,
252 				       u32 power, unsigned long *state)
253 {
254 	struct devfreq_cooling_device *dfc = cdev->devdata;
255 	struct devfreq *df = dfc->devfreq;
256 	struct devfreq_dev_status status;
257 	unsigned long freq;
258 	s32 est_power;
259 	int i;
260 
261 	mutex_lock(&df->lock);
262 	status = df->last_status;
263 	mutex_unlock(&df->lock);
264 
265 	freq = status.current_frequency;
266 
267 	if (dfc->power_ops && dfc->power_ops->get_real_power) {
268 		/* Scale for resource utilization */
269 		est_power = power * dfc->res_util;
270 		est_power /= SCALE_ERROR_MITIGATION;
271 	} else {
272 		/* Scale dynamic power for utilization */
273 		_normalize_load(&status);
274 		est_power = power << 10;
275 		est_power /= status.busy_time;
276 	}
277 
278 	/*
279 	 * Find the first cooling state that is within the power
280 	 * budget. The EM power table is sorted ascending.
281 	 */
282 	for (i = dfc->max_state; i > 0; i--)
283 		if (est_power >= dfc->em_pd->table[i].power)
284 			break;
285 
286 	*state = dfc->max_state - i;
287 	dfc->capped_state = *state;
288 
289 	trace_thermal_power_devfreq_limit(cdev, freq, *state, power);
290 	return 0;
291 }
292 
293 static struct thermal_cooling_device_ops devfreq_cooling_ops = {
294 	.get_max_state = devfreq_cooling_get_max_state,
295 	.get_cur_state = devfreq_cooling_get_cur_state,
296 	.set_cur_state = devfreq_cooling_set_cur_state,
297 };
298 
299 /**
300  * devfreq_cooling_gen_tables() - Generate frequency table.
301  * @dfc:	Pointer to devfreq cooling device.
302  * @num_opps:	Number of OPPs
303  *
304  * Generate frequency table which holds the frequencies in descending
305  * order. That way its indexed by cooling device state. This is for
306  * compatibility with drivers which do not register Energy Model.
307  *
308  * Return: 0 on success, negative error code on failure.
309  */
310 static int devfreq_cooling_gen_tables(struct devfreq_cooling_device *dfc,
311 				      int num_opps)
312 {
313 	struct devfreq *df = dfc->devfreq;
314 	struct device *dev = df->dev.parent;
315 	unsigned long freq;
316 	int i;
317 
318 	dfc->freq_table = kcalloc(num_opps, sizeof(*dfc->freq_table),
319 			     GFP_KERNEL);
320 	if (!dfc->freq_table)
321 		return -ENOMEM;
322 
323 	for (i = 0, freq = ULONG_MAX; i < num_opps; i++, freq--) {
324 		struct dev_pm_opp *opp;
325 
326 		opp = dev_pm_opp_find_freq_floor(dev, &freq);
327 		if (IS_ERR(opp)) {
328 			kfree(dfc->freq_table);
329 			return PTR_ERR(opp);
330 		}
331 
332 		dev_pm_opp_put(opp);
333 		dfc->freq_table[i] = freq;
334 	}
335 
336 	return 0;
337 }
338 
339 /**
340  * of_devfreq_cooling_register_power() - Register devfreq cooling device,
341  *                                      with OF and power information.
342  * @np:	Pointer to OF device_node.
343  * @df:	Pointer to devfreq device.
344  * @dfc_power:	Pointer to devfreq_cooling_power.
345  *
346  * Register a devfreq cooling device.  The available OPPs must be
347  * registered on the device.
348  *
349  * If @dfc_power is provided, the cooling device is registered with the
350  * power extensions.  For the power extensions to work correctly,
351  * devfreq should use the simple_ondemand governor, other governors
352  * are not currently supported.
353  */
354 struct thermal_cooling_device *
355 of_devfreq_cooling_register_power(struct device_node *np, struct devfreq *df,
356 				  struct devfreq_cooling_power *dfc_power)
357 {
358 	struct thermal_cooling_device *cdev;
359 	struct device *dev = df->dev.parent;
360 	struct devfreq_cooling_device *dfc;
361 	char *name;
362 	int err, num_opps;
363 
364 	dfc = kzalloc(sizeof(*dfc), GFP_KERNEL);
365 	if (!dfc)
366 		return ERR_PTR(-ENOMEM);
367 
368 	dfc->devfreq = df;
369 
370 	dfc->em_pd = em_pd_get(dev);
371 	if (dfc->em_pd) {
372 		devfreq_cooling_ops.get_requested_power =
373 			devfreq_cooling_get_requested_power;
374 		devfreq_cooling_ops.state2power = devfreq_cooling_state2power;
375 		devfreq_cooling_ops.power2state = devfreq_cooling_power2state;
376 
377 		dfc->power_ops = dfc_power;
378 
379 		num_opps = em_pd_nr_perf_states(dfc->em_pd);
380 	} else {
381 		/* Backward compatibility for drivers which do not use IPA */
382 		dev_dbg(dev, "missing EM for cooling device\n");
383 
384 		num_opps = dev_pm_opp_get_opp_count(dev);
385 
386 		err = devfreq_cooling_gen_tables(dfc, num_opps);
387 		if (err)
388 			goto free_dfc;
389 	}
390 
391 	if (num_opps <= 0) {
392 		err = -EINVAL;
393 		goto free_dfc;
394 	}
395 
396 	/* max_state is an index, not a counter */
397 	dfc->max_state = num_opps - 1;
398 
399 	err = dev_pm_qos_add_request(dev, &dfc->req_max_freq,
400 				     DEV_PM_QOS_MAX_FREQUENCY,
401 				     PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE);
402 	if (err < 0)
403 		goto free_table;
404 
405 	err = -ENOMEM;
406 	name = kasprintf(GFP_KERNEL, "devfreq-%s", dev_name(dev));
407 	if (!name)
408 		goto remove_qos_req;
409 
410 	cdev = thermal_of_cooling_device_register(np, name, dfc,
411 						  &devfreq_cooling_ops);
412 	kfree(name);
413 
414 	if (IS_ERR(cdev)) {
415 		err = PTR_ERR(cdev);
416 		dev_err(dev,
417 			"Failed to register devfreq cooling device (%d)\n",
418 			err);
419 		goto remove_qos_req;
420 	}
421 
422 	dfc->cdev = cdev;
423 
424 	return cdev;
425 
426 remove_qos_req:
427 	dev_pm_qos_remove_request(&dfc->req_max_freq);
428 free_table:
429 	kfree(dfc->freq_table);
430 free_dfc:
431 	kfree(dfc);
432 
433 	return ERR_PTR(err);
434 }
435 EXPORT_SYMBOL_GPL(of_devfreq_cooling_register_power);
436 
437 /**
438  * of_devfreq_cooling_register() - Register devfreq cooling device,
439  *                                with OF information.
440  * @np: Pointer to OF device_node.
441  * @df: Pointer to devfreq device.
442  */
443 struct thermal_cooling_device *
444 of_devfreq_cooling_register(struct device_node *np, struct devfreq *df)
445 {
446 	return of_devfreq_cooling_register_power(np, df, NULL);
447 }
448 EXPORT_SYMBOL_GPL(of_devfreq_cooling_register);
449 
450 /**
451  * devfreq_cooling_register() - Register devfreq cooling device.
452  * @df: Pointer to devfreq device.
453  */
454 struct thermal_cooling_device *devfreq_cooling_register(struct devfreq *df)
455 {
456 	return of_devfreq_cooling_register(NULL, df);
457 }
458 EXPORT_SYMBOL_GPL(devfreq_cooling_register);
459 
460 /**
461  * devfreq_cooling_em_register() - Register devfreq cooling device with
462  *		power information and automatically register Energy Model (EM)
463  * @df:		Pointer to devfreq device.
464  * @dfc_power:	Pointer to devfreq_cooling_power.
465  *
466  * Register a devfreq cooling device and automatically register EM. The
467  * available OPPs must be registered for the device.
468  *
469  * If @dfc_power is provided, the cooling device is registered with the
470  * power extensions. It is using the simple Energy Model which requires
471  * "dynamic-power-coefficient" a devicetree property. To not break drivers
472  * which miss that DT property, the function won't bail out when the EM
473  * registration failed. The cooling device will be registered if everything
474  * else is OK.
475  */
476 struct thermal_cooling_device *
477 devfreq_cooling_em_register(struct devfreq *df,
478 			    struct devfreq_cooling_power *dfc_power)
479 {
480 	struct thermal_cooling_device *cdev;
481 	struct device *dev;
482 	int ret;
483 
484 	if (IS_ERR_OR_NULL(df))
485 		return ERR_PTR(-EINVAL);
486 
487 	dev = df->dev.parent;
488 
489 	ret = dev_pm_opp_of_register_em(dev, NULL);
490 	if (ret)
491 		dev_dbg(dev, "Unable to register EM for devfreq cooling device (%d)\n",
492 			ret);
493 
494 	cdev = of_devfreq_cooling_register_power(dev->of_node, df, dfc_power);
495 
496 	if (IS_ERR_OR_NULL(cdev))
497 		em_dev_unregister_perf_domain(dev);
498 
499 	return cdev;
500 }
501 EXPORT_SYMBOL_GPL(devfreq_cooling_em_register);
502 
503 /**
504  * devfreq_cooling_unregister() - Unregister devfreq cooling device.
505  * @cdev: Pointer to devfreq cooling device to unregister.
506  *
507  * Unregisters devfreq cooling device and related Energy Model if it was
508  * present.
509  */
510 void devfreq_cooling_unregister(struct thermal_cooling_device *cdev)
511 {
512 	struct devfreq_cooling_device *dfc;
513 	struct device *dev;
514 
515 	if (IS_ERR_OR_NULL(cdev))
516 		return;
517 
518 	dfc = cdev->devdata;
519 	dev = dfc->devfreq->dev.parent;
520 
521 	thermal_cooling_device_unregister(dfc->cdev);
522 	dev_pm_qos_remove_request(&dfc->req_max_freq);
523 
524 	em_dev_unregister_perf_domain(dev);
525 
526 	kfree(dfc->freq_table);
527 	kfree(dfc);
528 }
529 EXPORT_SYMBOL_GPL(devfreq_cooling_unregister);
530