1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  *  thermal_helpers.c - helper functions to handle thermal devices
4  *
5  *  Copyright (C) 2016 Eduardo Valentin <edubezval@gmail.com>
6  *
7  *  Highly based on original thermal_core.c
8  *  Copyright (C) 2008 Intel Corp
9  *  Copyright (C) 2008 Zhang Rui <rui.zhang@intel.com>
10  *  Copyright (C) 2008 Sujith Thomas <sujith.thomas@intel.com>
11  */
12 
13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
14 
15 #include <linux/device.h>
16 #include <linux/err.h>
17 #include <linux/export.h>
18 #include <linux/slab.h>
19 #include <linux/string.h>
20 #include <linux/sysfs.h>
21 
22 #include <trace/events/thermal.h>
23 
24 #include "thermal_core.h"
25 
26 int get_tz_trend(struct thermal_zone_device *tz, int trip)
27 {
28 	enum thermal_trend trend;
29 
30 	if (tz->emul_temperature || !tz->ops->get_trend ||
31 	    tz->ops->get_trend(tz, trip, &trend)) {
32 		if (tz->temperature > tz->last_temperature)
33 			trend = THERMAL_TREND_RAISING;
34 		else if (tz->temperature < tz->last_temperature)
35 			trend = THERMAL_TREND_DROPPING;
36 		else
37 			trend = THERMAL_TREND_STABLE;
38 	}
39 
40 	return trend;
41 }
42 
43 struct thermal_instance *
44 get_thermal_instance(struct thermal_zone_device *tz,
45 		     struct thermal_cooling_device *cdev, int trip)
46 {
47 	struct thermal_instance *pos = NULL;
48 	struct thermal_instance *target_instance = NULL;
49 
50 	mutex_lock(&tz->lock);
51 	mutex_lock(&cdev->lock);
52 
53 	list_for_each_entry(pos, &tz->thermal_instances, tz_node) {
54 		if (pos->tz == tz && pos->trip == trip && pos->cdev == cdev) {
55 			target_instance = pos;
56 			break;
57 		}
58 	}
59 
60 	mutex_unlock(&cdev->lock);
61 	mutex_unlock(&tz->lock);
62 
63 	return target_instance;
64 }
65 EXPORT_SYMBOL(get_thermal_instance);
66 
67 /**
68  * __thermal_zone_get_temp() - returns the temperature of a thermal zone
69  * @tz: a valid pointer to a struct thermal_zone_device
70  * @temp: a valid pointer to where to store the resulting temperature.
71  *
72  * When a valid thermal zone reference is passed, it will fetch its
73  * temperature and fill @temp.
74  *
75  * Both tz and tz->ops must be valid pointers when calling this function,
76  * and the tz->ops->get_temp callback must be provided.
77  * The function must be called under tz->lock.
78  *
79  * Return: On success returns 0, an error code otherwise
80  */
81 int __thermal_zone_get_temp(struct thermal_zone_device *tz, int *temp)
82 {
83 	int ret = -EINVAL;
84 	int count;
85 	int crit_temp = INT_MAX;
86 	enum thermal_trip_type type;
87 
88 	lockdep_assert_held(&tz->lock);
89 
90 	ret = tz->ops->get_temp(tz, temp);
91 
92 	if (IS_ENABLED(CONFIG_THERMAL_EMULATION) && tz->emul_temperature) {
93 		for (count = 0; count < tz->num_trips; count++) {
94 			ret = tz->ops->get_trip_type(tz, count, &type);
95 			if (!ret && type == THERMAL_TRIP_CRITICAL) {
96 				ret = tz->ops->get_trip_temp(tz, count,
97 						&crit_temp);
98 				break;
99 			}
100 		}
101 
102 		/*
103 		 * Only allow emulating a temperature when the real temperature
104 		 * is below the critical temperature so that the emulation code
105 		 * cannot hide critical conditions.
106 		 */
107 		if (!ret && *temp < crit_temp)
108 			*temp = tz->emul_temperature;
109 	}
110 
111 	return ret;
112 }
113 
114 /**
115  * thermal_zone_get_temp() - returns the temperature of a thermal zone
116  * @tz: a valid pointer to a struct thermal_zone_device
117  * @temp: a valid pointer to where to store the resulting temperature.
118  *
119  * When a valid thermal zone reference is passed, it will fetch its
120  * temperature and fill @temp.
121  *
122  * Return: On success returns 0, an error code otherwise
123  */
124 int thermal_zone_get_temp(struct thermal_zone_device *tz, int *temp)
125 {
126 	int ret;
127 
128 	if (IS_ERR_OR_NULL(tz))
129 		return -EINVAL;
130 
131 	mutex_lock(&tz->lock);
132 
133 	if (!tz->ops->get_temp) {
134 		ret = -EINVAL;
135 		goto unlock;
136 	}
137 
138 	if (device_is_registered(&tz->device))
139 		ret = __thermal_zone_get_temp(tz, temp);
140 	else
141 		ret = -ENODEV;
142 
143 unlock:
144 	mutex_unlock(&tz->lock);
145 
146 	return ret;
147 }
148 EXPORT_SYMBOL_GPL(thermal_zone_get_temp);
149 
150 /**
151  * __thermal_zone_set_trips - Computes the next trip points for the driver
152  * @tz: a pointer to a thermal zone device structure
153  *
154  * The function computes the next temperature boundaries by browsing
155  * the trip points. The result is the closer low and high trip points
156  * to the current temperature. These values are passed to the backend
157  * driver to let it set its own notification mechanism (usually an
158  * interrupt).
159  *
160  * This function must be called with tz->lock held. Both tz and tz->ops
161  * must be valid pointers.
162  *
163  * It does not return a value
164  */
165 void __thermal_zone_set_trips(struct thermal_zone_device *tz)
166 {
167 	int low = -INT_MAX;
168 	int high = INT_MAX;
169 	int trip_temp, hysteresis;
170 	int i, ret;
171 
172 	lockdep_assert_held(&tz->lock);
173 
174 	if (!tz->ops->set_trips || !tz->ops->get_trip_hyst)
175 		return;
176 
177 	for (i = 0; i < tz->num_trips; i++) {
178 		int trip_low;
179 
180 		tz->ops->get_trip_temp(tz, i, &trip_temp);
181 		tz->ops->get_trip_hyst(tz, i, &hysteresis);
182 
183 		trip_low = trip_temp - hysteresis;
184 
185 		if (trip_low < tz->temperature && trip_low > low)
186 			low = trip_low;
187 
188 		if (trip_temp > tz->temperature && trip_temp < high)
189 			high = trip_temp;
190 	}
191 
192 	/* No need to change trip points */
193 	if (tz->prev_low_trip == low && tz->prev_high_trip == high)
194 		return;
195 
196 	tz->prev_low_trip = low;
197 	tz->prev_high_trip = high;
198 
199 	dev_dbg(&tz->device,
200 		"new temperature boundaries: %d < x < %d\n", low, high);
201 
202 	/*
203 	 * Set a temperature window. When this window is left the driver
204 	 * must inform the thermal core via thermal_zone_device_update.
205 	 */
206 	ret = tz->ops->set_trips(tz, low, high);
207 	if (ret)
208 		dev_err(&tz->device, "Failed to set trips: %d\n", ret);
209 }
210 
211 static void thermal_cdev_set_cur_state(struct thermal_cooling_device *cdev,
212 				       int target)
213 {
214 	if (cdev->ops->set_cur_state(cdev, target))
215 		return;
216 
217 	thermal_notify_cdev_state_update(cdev->id, target);
218 	thermal_cooling_device_stats_update(cdev, target);
219 }
220 
221 void __thermal_cdev_update(struct thermal_cooling_device *cdev)
222 {
223 	struct thermal_instance *instance;
224 	unsigned long target = 0;
225 
226 	/* Make sure cdev enters the deepest cooling state */
227 	list_for_each_entry(instance, &cdev->thermal_instances, cdev_node) {
228 		dev_dbg(&cdev->device, "zone%d->target=%lu\n",
229 			instance->tz->id, instance->target);
230 		if (instance->target == THERMAL_NO_TARGET)
231 			continue;
232 		if (instance->target > target)
233 			target = instance->target;
234 	}
235 
236 	thermal_cdev_set_cur_state(cdev, target);
237 
238 	trace_cdev_update(cdev, target);
239 	dev_dbg(&cdev->device, "set to state %lu\n", target);
240 }
241 
242 /**
243  * thermal_cdev_update - update cooling device state if needed
244  * @cdev:	pointer to struct thermal_cooling_device
245  *
246  * Update the cooling device state if there is a need.
247  */
248 void thermal_cdev_update(struct thermal_cooling_device *cdev)
249 {
250 	mutex_lock(&cdev->lock);
251 	if (!cdev->updated) {
252 		__thermal_cdev_update(cdev);
253 		cdev->updated = true;
254 	}
255 	mutex_unlock(&cdev->lock);
256 }
257 
258 /**
259  * thermal_zone_get_slope - return the slope attribute of the thermal zone
260  * @tz: thermal zone device with the slope attribute
261  *
262  * Return: If the thermal zone device has a slope attribute, return it, else
263  * return 1.
264  */
265 int thermal_zone_get_slope(struct thermal_zone_device *tz)
266 {
267 	if (tz && tz->tzp)
268 		return tz->tzp->slope;
269 	return 1;
270 }
271 EXPORT_SYMBOL_GPL(thermal_zone_get_slope);
272 
273 /**
274  * thermal_zone_get_offset - return the offset attribute of the thermal zone
275  * @tz: thermal zone device with the offset attribute
276  *
277  * Return: If the thermal zone device has a offset attribute, return it, else
278  * return 0.
279  */
280 int thermal_zone_get_offset(struct thermal_zone_device *tz)
281 {
282 	if (tz && tz->tzp)
283 		return tz->tzp->offset;
284 	return 0;
285 }
286 EXPORT_SYMBOL_GPL(thermal_zone_get_offset);
287