1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * A power allocator to manage temperature
4  *
5  * Copyright (C) 2014 ARM Ltd.
6  *
7  */
8 
9 #define pr_fmt(fmt) "Power allocator: " fmt
10 
11 #include <linux/slab.h>
12 #include <linux/thermal.h>
13 
14 #define CREATE_TRACE_POINTS
15 #include <trace/events/thermal_power_allocator.h>
16 
17 #include "thermal_core.h"
18 
19 #define INVALID_TRIP -1
20 
21 #define FRAC_BITS 10
22 #define int_to_frac(x) ((x) << FRAC_BITS)
23 #define frac_to_int(x) ((x) >> FRAC_BITS)
24 
25 /**
26  * mul_frac() - multiply two fixed-point numbers
27  * @x:	first multiplicand
28  * @y:	second multiplicand
29  *
30  * Return: the result of multiplying two fixed-point numbers.  The
31  * result is also a fixed-point number.
32  */
33 static inline s64 mul_frac(s64 x, s64 y)
34 {
35 	return (x * y) >> FRAC_BITS;
36 }
37 
38 /**
39  * div_frac() - divide two fixed-point numbers
40  * @x:	the dividend
41  * @y:	the divisor
42  *
43  * Return: the result of dividing two fixed-point numbers.  The
44  * result is also a fixed-point number.
45  */
46 static inline s64 div_frac(s64 x, s64 y)
47 {
48 	return div_s64(x << FRAC_BITS, y);
49 }
50 
51 /**
52  * struct power_allocator_params - parameters for the power allocator governor
53  * @allocated_tzp:	whether we have allocated tzp for this thermal zone and
54  *			it needs to be freed on unbind
55  * @err_integral:	accumulated error in the PID controller.
56  * @prev_err:	error in the previous iteration of the PID controller.
57  *		Used to calculate the derivative term.
58  * @trip_switch_on:	first passive trip point of the thermal zone.  The
59  *			governor switches on when this trip point is crossed.
60  *			If the thermal zone only has one passive trip point,
61  *			@trip_switch_on should be INVALID_TRIP.
62  * @trip_max_desired_temperature:	last passive trip point of the thermal
63  *					zone.  The temperature we are
64  *					controlling for.
65  * @sustainable_power:	Sustainable power (heat) that this thermal zone can
66  *			dissipate
67  */
68 struct power_allocator_params {
69 	bool allocated_tzp;
70 	s64 err_integral;
71 	s32 prev_err;
72 	int trip_switch_on;
73 	int trip_max_desired_temperature;
74 	u32 sustainable_power;
75 };
76 
77 /**
78  * estimate_sustainable_power() - Estimate the sustainable power of a thermal zone
79  * @tz: thermal zone we are operating in
80  *
81  * For thermal zones that don't provide a sustainable_power in their
82  * thermal_zone_params, estimate one.  Calculate it using the minimum
83  * power of all the cooling devices as that gives a valid value that
84  * can give some degree of functionality.  For optimal performance of
85  * this governor, provide a sustainable_power in the thermal zone's
86  * thermal_zone_params.
87  */
88 static u32 estimate_sustainable_power(struct thermal_zone_device *tz)
89 {
90 	u32 sustainable_power = 0;
91 	struct thermal_instance *instance;
92 	struct power_allocator_params *params = tz->governor_data;
93 
94 	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
95 		struct thermal_cooling_device *cdev = instance->cdev;
96 		u32 min_power;
97 
98 		if (instance->trip != params->trip_max_desired_temperature)
99 			continue;
100 
101 		if (!cdev_is_power_actor(cdev))
102 			continue;
103 
104 		if (cdev->ops->state2power(cdev, instance->upper, &min_power))
105 			continue;
106 
107 		sustainable_power += min_power;
108 	}
109 
110 	return sustainable_power;
111 }
112 
113 /**
114  * estimate_pid_constants() - Estimate the constants for the PID controller
115  * @tz:		thermal zone for which to estimate the constants
116  * @sustainable_power:	sustainable power for the thermal zone
117  * @trip_switch_on:	trip point number for the switch on temperature
118  * @control_temp:	target temperature for the power allocator governor
119  *
120  * This function is used to update the estimation of the PID
121  * controller constants in struct thermal_zone_parameters.
122  */
123 static void estimate_pid_constants(struct thermal_zone_device *tz,
124 				   u32 sustainable_power, int trip_switch_on,
125 				   int control_temp)
126 {
127 	struct thermal_trip trip;
128 	u32 temperature_threshold = control_temp;
129 	int ret;
130 	s32 k_i;
131 
132 	ret = __thermal_zone_get_trip(tz, trip_switch_on, &trip);
133 	if (!ret)
134 		temperature_threshold -= trip.temperature;
135 
136 	/*
137 	 * estimate_pid_constants() tries to find appropriate default
138 	 * values for thermal zones that don't provide them. If a
139 	 * system integrator has configured a thermal zone with two
140 	 * passive trip points at the same temperature, that person
141 	 * hasn't put any effort to set up the thermal zone properly
142 	 * so just give up.
143 	 */
144 	if (!temperature_threshold)
145 		return;
146 
147 	tz->tzp->k_po = int_to_frac(sustainable_power) /
148 		temperature_threshold;
149 
150 	tz->tzp->k_pu = int_to_frac(2 * sustainable_power) /
151 		temperature_threshold;
152 
153 	k_i = tz->tzp->k_pu / 10;
154 	tz->tzp->k_i = k_i > 0 ? k_i : 1;
155 
156 	/*
157 	 * The default for k_d and integral_cutoff is 0, so we can
158 	 * leave them as they are.
159 	 */
160 }
161 
162 /**
163  * get_sustainable_power() - Get the right sustainable power
164  * @tz:		thermal zone for which to estimate the constants
165  * @params:	parameters for the power allocator governor
166  * @control_temp:	target temperature for the power allocator governor
167  *
168  * This function is used for getting the proper sustainable power value based
169  * on variables which might be updated by the user sysfs interface. If that
170  * happen the new value is going to be estimated and updated. It is also used
171  * after thermal zone binding, where the initial values where set to 0.
172  */
173 static u32 get_sustainable_power(struct thermal_zone_device *tz,
174 				 struct power_allocator_params *params,
175 				 int control_temp)
176 {
177 	u32 sustainable_power;
178 
179 	if (!tz->tzp->sustainable_power)
180 		sustainable_power = estimate_sustainable_power(tz);
181 	else
182 		sustainable_power = tz->tzp->sustainable_power;
183 
184 	/* Check if it's init value 0 or there was update via sysfs */
185 	if (sustainable_power != params->sustainable_power) {
186 		estimate_pid_constants(tz, sustainable_power,
187 				       params->trip_switch_on, control_temp);
188 
189 		/* Do the estimation only once and make available in sysfs */
190 		tz->tzp->sustainable_power = sustainable_power;
191 		params->sustainable_power = sustainable_power;
192 	}
193 
194 	return sustainable_power;
195 }
196 
197 /**
198  * pid_controller() - PID controller
199  * @tz:	thermal zone we are operating in
200  * @control_temp:	the target temperature in millicelsius
201  * @max_allocatable_power:	maximum allocatable power for this thermal zone
202  *
203  * This PID controller increases the available power budget so that the
204  * temperature of the thermal zone gets as close as possible to
205  * @control_temp and limits the power if it exceeds it.  k_po is the
206  * proportional term when we are overshooting, k_pu is the
207  * proportional term when we are undershooting.  integral_cutoff is a
208  * threshold below which we stop accumulating the error.  The
209  * accumulated error is only valid if the requested power will make
210  * the system warmer.  If the system is mostly idle, there's no point
211  * in accumulating positive error.
212  *
213  * Return: The power budget for the next period.
214  */
215 static u32 pid_controller(struct thermal_zone_device *tz,
216 			  int control_temp,
217 			  u32 max_allocatable_power)
218 {
219 	s64 p, i, d, power_range;
220 	s32 err, max_power_frac;
221 	u32 sustainable_power;
222 	struct power_allocator_params *params = tz->governor_data;
223 
224 	max_power_frac = int_to_frac(max_allocatable_power);
225 
226 	sustainable_power = get_sustainable_power(tz, params, control_temp);
227 
228 	err = control_temp - tz->temperature;
229 	err = int_to_frac(err);
230 
231 	/* Calculate the proportional term */
232 	p = mul_frac(err < 0 ? tz->tzp->k_po : tz->tzp->k_pu, err);
233 
234 	/*
235 	 * Calculate the integral term
236 	 *
237 	 * if the error is less than cut off allow integration (but
238 	 * the integral is limited to max power)
239 	 */
240 	i = mul_frac(tz->tzp->k_i, params->err_integral);
241 
242 	if (err < int_to_frac(tz->tzp->integral_cutoff)) {
243 		s64 i_next = i + mul_frac(tz->tzp->k_i, err);
244 
245 		if (abs(i_next) < max_power_frac) {
246 			i = i_next;
247 			params->err_integral += err;
248 		}
249 	}
250 
251 	/*
252 	 * Calculate the derivative term
253 	 *
254 	 * We do err - prev_err, so with a positive k_d, a decreasing
255 	 * error (i.e. driving closer to the line) results in less
256 	 * power being applied, slowing down the controller)
257 	 */
258 	d = mul_frac(tz->tzp->k_d, err - params->prev_err);
259 	d = div_frac(d, jiffies_to_msecs(tz->passive_delay_jiffies));
260 	params->prev_err = err;
261 
262 	power_range = p + i + d;
263 
264 	/* feed-forward the known sustainable dissipatable power */
265 	power_range = sustainable_power + frac_to_int(power_range);
266 
267 	power_range = clamp(power_range, (s64)0, (s64)max_allocatable_power);
268 
269 	trace_thermal_power_allocator_pid(tz, frac_to_int(err),
270 					  frac_to_int(params->err_integral),
271 					  frac_to_int(p), frac_to_int(i),
272 					  frac_to_int(d), power_range);
273 
274 	return power_range;
275 }
276 
277 /**
278  * power_actor_set_power() - limit the maximum power a cooling device consumes
279  * @cdev:	pointer to &thermal_cooling_device
280  * @instance:	thermal instance to update
281  * @power:	the power in milliwatts
282  *
283  * Set the cooling device to consume at most @power milliwatts. The limit is
284  * expected to be a cap at the maximum power consumption.
285  *
286  * Return: 0 on success, -EINVAL if the cooling device does not
287  * implement the power actor API or -E* for other failures.
288  */
289 static int
290 power_actor_set_power(struct thermal_cooling_device *cdev,
291 		      struct thermal_instance *instance, u32 power)
292 {
293 	unsigned long state;
294 	int ret;
295 
296 	ret = cdev->ops->power2state(cdev, power, &state);
297 	if (ret)
298 		return ret;
299 
300 	instance->target = clamp_val(state, instance->lower, instance->upper);
301 	mutex_lock(&cdev->lock);
302 	__thermal_cdev_update(cdev);
303 	mutex_unlock(&cdev->lock);
304 
305 	return 0;
306 }
307 
308 /**
309  * divvy_up_power() - divvy the allocated power between the actors
310  * @req_power:	each actor's requested power
311  * @max_power:	each actor's maximum available power
312  * @num_actors:	size of the @req_power, @max_power and @granted_power's array
313  * @total_req_power: sum of @req_power
314  * @power_range:	total allocated power
315  * @granted_power:	output array: each actor's granted power
316  * @extra_actor_power:	an appropriately sized array to be used in the
317  *			function as temporary storage of the extra power given
318  *			to the actors
319  *
320  * This function divides the total allocated power (@power_range)
321  * fairly between the actors.  It first tries to give each actor a
322  * share of the @power_range according to how much power it requested
323  * compared to the rest of the actors.  For example, if only one actor
324  * requests power, then it receives all the @power_range.  If
325  * three actors each requests 1mW, each receives a third of the
326  * @power_range.
327  *
328  * If any actor received more than their maximum power, then that
329  * surplus is re-divvied among the actors based on how far they are
330  * from their respective maximums.
331  *
332  * Granted power for each actor is written to @granted_power, which
333  * should've been allocated by the calling function.
334  */
335 static void divvy_up_power(u32 *req_power, u32 *max_power, int num_actors,
336 			   u32 total_req_power, u32 power_range,
337 			   u32 *granted_power, u32 *extra_actor_power)
338 {
339 	u32 extra_power, capped_extra_power;
340 	int i;
341 
342 	/*
343 	 * Prevent division by 0 if none of the actors request power.
344 	 */
345 	if (!total_req_power)
346 		total_req_power = 1;
347 
348 	capped_extra_power = 0;
349 	extra_power = 0;
350 	for (i = 0; i < num_actors; i++) {
351 		u64 req_range = (u64)req_power[i] * power_range;
352 
353 		granted_power[i] = DIV_ROUND_CLOSEST_ULL(req_range,
354 							 total_req_power);
355 
356 		if (granted_power[i] > max_power[i]) {
357 			extra_power += granted_power[i] - max_power[i];
358 			granted_power[i] = max_power[i];
359 		}
360 
361 		extra_actor_power[i] = max_power[i] - granted_power[i];
362 		capped_extra_power += extra_actor_power[i];
363 	}
364 
365 	if (!extra_power)
366 		return;
367 
368 	/*
369 	 * Re-divvy the reclaimed extra among actors based on
370 	 * how far they are from the max
371 	 */
372 	extra_power = min(extra_power, capped_extra_power);
373 	if (capped_extra_power > 0)
374 		for (i = 0; i < num_actors; i++) {
375 			u64 extra_range = (u64)extra_actor_power[i] * extra_power;
376 			granted_power[i] += DIV_ROUND_CLOSEST_ULL(extra_range,
377 							 capped_extra_power);
378 		}
379 }
380 
381 static int allocate_power(struct thermal_zone_device *tz,
382 			  int control_temp)
383 {
384 	struct thermal_instance *instance;
385 	struct power_allocator_params *params = tz->governor_data;
386 	u32 *req_power, *max_power, *granted_power, *extra_actor_power;
387 	u32 *weighted_req_power;
388 	u32 total_req_power, max_allocatable_power, total_weighted_req_power;
389 	u32 total_granted_power, power_range;
390 	int i, num_actors, total_weight, ret = 0;
391 	int trip_max_desired_temperature = params->trip_max_desired_temperature;
392 
393 	num_actors = 0;
394 	total_weight = 0;
395 	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
396 		if ((instance->trip == trip_max_desired_temperature) &&
397 		    cdev_is_power_actor(instance->cdev)) {
398 			num_actors++;
399 			total_weight += instance->weight;
400 		}
401 	}
402 
403 	if (!num_actors)
404 		return -ENODEV;
405 
406 	/*
407 	 * We need to allocate five arrays of the same size:
408 	 * req_power, max_power, granted_power, extra_actor_power and
409 	 * weighted_req_power.  They are going to be needed until this
410 	 * function returns.  Allocate them all in one go to simplify
411 	 * the allocation and deallocation logic.
412 	 */
413 	BUILD_BUG_ON(sizeof(*req_power) != sizeof(*max_power));
414 	BUILD_BUG_ON(sizeof(*req_power) != sizeof(*granted_power));
415 	BUILD_BUG_ON(sizeof(*req_power) != sizeof(*extra_actor_power));
416 	BUILD_BUG_ON(sizeof(*req_power) != sizeof(*weighted_req_power));
417 	req_power = kcalloc(num_actors * 5, sizeof(*req_power), GFP_KERNEL);
418 	if (!req_power)
419 		return -ENOMEM;
420 
421 	max_power = &req_power[num_actors];
422 	granted_power = &req_power[2 * num_actors];
423 	extra_actor_power = &req_power[3 * num_actors];
424 	weighted_req_power = &req_power[4 * num_actors];
425 
426 	i = 0;
427 	total_weighted_req_power = 0;
428 	total_req_power = 0;
429 	max_allocatable_power = 0;
430 
431 	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
432 		int weight;
433 		struct thermal_cooling_device *cdev = instance->cdev;
434 
435 		if (instance->trip != trip_max_desired_temperature)
436 			continue;
437 
438 		if (!cdev_is_power_actor(cdev))
439 			continue;
440 
441 		if (cdev->ops->get_requested_power(cdev, &req_power[i]))
442 			continue;
443 
444 		if (!total_weight)
445 			weight = 1 << FRAC_BITS;
446 		else
447 			weight = instance->weight;
448 
449 		weighted_req_power[i] = frac_to_int(weight * req_power[i]);
450 
451 		if (cdev->ops->state2power(cdev, instance->lower,
452 					   &max_power[i]))
453 			continue;
454 
455 		total_req_power += req_power[i];
456 		max_allocatable_power += max_power[i];
457 		total_weighted_req_power += weighted_req_power[i];
458 
459 		i++;
460 	}
461 
462 	power_range = pid_controller(tz, control_temp, max_allocatable_power);
463 
464 	divvy_up_power(weighted_req_power, max_power, num_actors,
465 		       total_weighted_req_power, power_range, granted_power,
466 		       extra_actor_power);
467 
468 	total_granted_power = 0;
469 	i = 0;
470 	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
471 		if (instance->trip != trip_max_desired_temperature)
472 			continue;
473 
474 		if (!cdev_is_power_actor(instance->cdev))
475 			continue;
476 
477 		power_actor_set_power(instance->cdev, instance,
478 				      granted_power[i]);
479 		total_granted_power += granted_power[i];
480 
481 		i++;
482 	}
483 
484 	trace_thermal_power_allocator(tz, req_power, total_req_power,
485 				      granted_power, total_granted_power,
486 				      num_actors, power_range,
487 				      max_allocatable_power, tz->temperature,
488 				      control_temp - tz->temperature);
489 
490 	kfree(req_power);
491 
492 	return ret;
493 }
494 
495 /**
496  * get_governor_trips() - get the number of the two trip points that are key for this governor
497  * @tz:	thermal zone to operate on
498  * @params:	pointer to private data for this governor
499  *
500  * The power allocator governor works optimally with two trips points:
501  * a "switch on" trip point and a "maximum desired temperature".  These
502  * are defined as the first and last passive trip points.
503  *
504  * If there is only one trip point, then that's considered to be the
505  * "maximum desired temperature" trip point and the governor is always
506  * on.  If there are no passive or active trip points, then the
507  * governor won't do anything.  In fact, its throttle function
508  * won't be called at all.
509  */
510 static void get_governor_trips(struct thermal_zone_device *tz,
511 			       struct power_allocator_params *params)
512 {
513 	int i, last_active, last_passive;
514 	bool found_first_passive;
515 
516 	found_first_passive = false;
517 	last_active = INVALID_TRIP;
518 	last_passive = INVALID_TRIP;
519 
520 	for (i = 0; i < tz->num_trips; i++) {
521 		struct thermal_trip trip;
522 		int ret;
523 
524 		ret = __thermal_zone_get_trip(tz, i, &trip);
525 		if (ret) {
526 			dev_warn(&tz->device,
527 				 "Failed to get trip point %d type: %d\n", i,
528 				 ret);
529 			continue;
530 		}
531 
532 		if (trip.type == THERMAL_TRIP_PASSIVE) {
533 			if (!found_first_passive) {
534 				params->trip_switch_on = i;
535 				found_first_passive = true;
536 			} else  {
537 				last_passive = i;
538 			}
539 		} else if (trip.type == THERMAL_TRIP_ACTIVE) {
540 			last_active = i;
541 		} else {
542 			break;
543 		}
544 	}
545 
546 	if (last_passive != INVALID_TRIP) {
547 		params->trip_max_desired_temperature = last_passive;
548 	} else if (found_first_passive) {
549 		params->trip_max_desired_temperature = params->trip_switch_on;
550 		params->trip_switch_on = INVALID_TRIP;
551 	} else {
552 		params->trip_switch_on = INVALID_TRIP;
553 		params->trip_max_desired_temperature = last_active;
554 	}
555 }
556 
557 static void reset_pid_controller(struct power_allocator_params *params)
558 {
559 	params->err_integral = 0;
560 	params->prev_err = 0;
561 }
562 
563 static void allow_maximum_power(struct thermal_zone_device *tz, bool update)
564 {
565 	struct thermal_instance *instance;
566 	struct power_allocator_params *params = tz->governor_data;
567 	u32 req_power;
568 
569 	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
570 		struct thermal_cooling_device *cdev = instance->cdev;
571 
572 		if ((instance->trip != params->trip_max_desired_temperature) ||
573 		    (!cdev_is_power_actor(instance->cdev)))
574 			continue;
575 
576 		instance->target = 0;
577 		mutex_lock(&instance->cdev->lock);
578 		/*
579 		 * Call for updating the cooling devices local stats and avoid
580 		 * periods of dozen of seconds when those have not been
581 		 * maintained.
582 		 */
583 		cdev->ops->get_requested_power(cdev, &req_power);
584 
585 		if (update)
586 			__thermal_cdev_update(instance->cdev);
587 
588 		mutex_unlock(&instance->cdev->lock);
589 	}
590 }
591 
592 /**
593  * check_power_actors() - Check all cooling devices and warn when they are
594  *			not power actors
595  * @tz:		thermal zone to operate on
596  *
597  * Check all cooling devices in the @tz and warn every time they are missing
598  * power actor API. The warning should help to investigate the issue, which
599  * could be e.g. lack of Energy Model for a given device.
600  *
601  * Return: 0 on success, -EINVAL if any cooling device does not implement
602  * the power actor API.
603  */
604 static int check_power_actors(struct thermal_zone_device *tz)
605 {
606 	struct thermal_instance *instance;
607 	int ret = 0;
608 
609 	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
610 		if (!cdev_is_power_actor(instance->cdev)) {
611 			dev_warn(&tz->device, "power_allocator: %s is not a power actor\n",
612 				 instance->cdev->type);
613 			ret = -EINVAL;
614 		}
615 	}
616 
617 	return ret;
618 }
619 
620 /**
621  * power_allocator_bind() - bind the power_allocator governor to a thermal zone
622  * @tz:	thermal zone to bind it to
623  *
624  * Initialize the PID controller parameters and bind it to the thermal
625  * zone.
626  *
627  * Return: 0 on success, or -ENOMEM if we ran out of memory, or -EINVAL
628  * when there are unsupported cooling devices in the @tz.
629  */
630 static int power_allocator_bind(struct thermal_zone_device *tz)
631 {
632 	int ret;
633 	struct power_allocator_params *params;
634 	struct thermal_trip trip;
635 
636 	ret = check_power_actors(tz);
637 	if (ret)
638 		return ret;
639 
640 	params = kzalloc(sizeof(*params), GFP_KERNEL);
641 	if (!params)
642 		return -ENOMEM;
643 
644 	if (!tz->tzp) {
645 		tz->tzp = kzalloc(sizeof(*tz->tzp), GFP_KERNEL);
646 		if (!tz->tzp) {
647 			ret = -ENOMEM;
648 			goto free_params;
649 		}
650 
651 		params->allocated_tzp = true;
652 	}
653 
654 	if (!tz->tzp->sustainable_power)
655 		dev_warn(&tz->device, "power_allocator: sustainable_power will be estimated\n");
656 
657 	get_governor_trips(tz, params);
658 
659 	if (tz->num_trips > 0) {
660 		ret = __thermal_zone_get_trip(tz, params->trip_max_desired_temperature,
661 					      &trip);
662 		if (!ret)
663 			estimate_pid_constants(tz, tz->tzp->sustainable_power,
664 					       params->trip_switch_on,
665 					       trip.temperature);
666 	}
667 
668 	reset_pid_controller(params);
669 
670 	tz->governor_data = params;
671 
672 	return 0;
673 
674 free_params:
675 	kfree(params);
676 
677 	return ret;
678 }
679 
680 static void power_allocator_unbind(struct thermal_zone_device *tz)
681 {
682 	struct power_allocator_params *params = tz->governor_data;
683 
684 	dev_dbg(&tz->device, "Unbinding from thermal zone %d\n", tz->id);
685 
686 	if (params->allocated_tzp) {
687 		kfree(tz->tzp);
688 		tz->tzp = NULL;
689 	}
690 
691 	kfree(tz->governor_data);
692 	tz->governor_data = NULL;
693 }
694 
695 static int power_allocator_throttle(struct thermal_zone_device *tz, int trip_id)
696 {
697 	struct power_allocator_params *params = tz->governor_data;
698 	struct thermal_trip trip;
699 	int ret;
700 	bool update;
701 
702 	lockdep_assert_held(&tz->lock);
703 
704 	/*
705 	 * We get called for every trip point but we only need to do
706 	 * our calculations once
707 	 */
708 	if (trip_id != params->trip_max_desired_temperature)
709 		return 0;
710 
711 	ret = __thermal_zone_get_trip(tz, params->trip_switch_on, &trip);
712 	if (!ret && (tz->temperature < trip.temperature)) {
713 		update = (tz->last_temperature >= trip.temperature);
714 		tz->passive = 0;
715 		reset_pid_controller(params);
716 		allow_maximum_power(tz, update);
717 		return 0;
718 	}
719 
720 	tz->passive = 1;
721 
722 	ret = __thermal_zone_get_trip(tz, params->trip_max_desired_temperature, &trip);
723 	if (ret) {
724 		dev_warn(&tz->device, "Failed to get the maximum desired temperature: %d\n",
725 			 ret);
726 		return ret;
727 	}
728 
729 	return allocate_power(tz, trip.temperature);
730 }
731 
732 static struct thermal_governor thermal_gov_power_allocator = {
733 	.name		= "power_allocator",
734 	.bind_to_tz	= power_allocator_bind,
735 	.unbind_from_tz	= power_allocator_unbind,
736 	.throttle	= power_allocator_throttle,
737 };
738 THERMAL_GOVERNOR_DECLARE(thermal_gov_power_allocator);
739