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 int __thermal_zone_get_temp(struct thermal_zone_device *tz, int *temp)
68 {
69 	int ret = -EINVAL;
70 	int count;
71 	int crit_temp = INT_MAX;
72 	enum thermal_trip_type type;
73 
74 	lockdep_assert_held(&tz->lock);
75 
76 	if (!tz || IS_ERR(tz) || !tz->ops->get_temp)
77 		return -EINVAL;
78 
79 	ret = tz->ops->get_temp(tz, temp);
80 
81 	if (IS_ENABLED(CONFIG_THERMAL_EMULATION) && tz->emul_temperature) {
82 		for (count = 0; count < tz->num_trips; count++) {
83 			ret = tz->ops->get_trip_type(tz, count, &type);
84 			if (!ret && type == THERMAL_TRIP_CRITICAL) {
85 				ret = tz->ops->get_trip_temp(tz, count,
86 						&crit_temp);
87 				break;
88 			}
89 		}
90 
91 		/*
92 		 * Only allow emulating a temperature when the real temperature
93 		 * is below the critical temperature so that the emulation code
94 		 * cannot hide critical conditions.
95 		 */
96 		if (!ret && *temp < crit_temp)
97 			*temp = tz->emul_temperature;
98 	}
99 
100 	return ret;
101 }
102 
103 /**
104  * thermal_zone_get_temp() - returns the temperature of a thermal zone
105  * @tz: a valid pointer to a struct thermal_zone_device
106  * @temp: a valid pointer to where to store the resulting temperature.
107  *
108  * When a valid thermal zone reference is passed, it will fetch its
109  * temperature and fill @temp.
110  *
111  * Return: On success returns 0, an error code otherwise
112  */
113 int thermal_zone_get_temp(struct thermal_zone_device *tz, int *temp)
114 {
115 	int ret;
116 
117 	mutex_lock(&tz->lock);
118 	ret = __thermal_zone_get_temp(tz, temp);
119 	mutex_unlock(&tz->lock);
120 
121 	return ret;
122 }
123 EXPORT_SYMBOL_GPL(thermal_zone_get_temp);
124 
125 void __thermal_zone_set_trips(struct thermal_zone_device *tz)
126 {
127 	int low = -INT_MAX;
128 	int high = INT_MAX;
129 	int trip_temp, hysteresis;
130 	int i, ret;
131 
132 	lockdep_assert_held(&tz->lock);
133 
134 	if (!tz->ops->set_trips || !tz->ops->get_trip_hyst)
135 		return;
136 
137 	for (i = 0; i < tz->num_trips; i++) {
138 		int trip_low;
139 
140 		tz->ops->get_trip_temp(tz, i, &trip_temp);
141 		tz->ops->get_trip_hyst(tz, i, &hysteresis);
142 
143 		trip_low = trip_temp - hysteresis;
144 
145 		if (trip_low < tz->temperature && trip_low > low)
146 			low = trip_low;
147 
148 		if (trip_temp > tz->temperature && trip_temp < high)
149 			high = trip_temp;
150 	}
151 
152 	/* No need to change trip points */
153 	if (tz->prev_low_trip == low && tz->prev_high_trip == high)
154 		return;
155 
156 	tz->prev_low_trip = low;
157 	tz->prev_high_trip = high;
158 
159 	dev_dbg(&tz->device,
160 		"new temperature boundaries: %d < x < %d\n", low, high);
161 
162 	/*
163 	 * Set a temperature window. When this window is left the driver
164 	 * must inform the thermal core via thermal_zone_device_update.
165 	 */
166 	ret = tz->ops->set_trips(tz, low, high);
167 	if (ret)
168 		dev_err(&tz->device, "Failed to set trips: %d\n", ret);
169 }
170 
171 /**
172  * thermal_zone_set_trips - Computes the next trip points for the driver
173  * @tz: a pointer to a thermal zone device structure
174  *
175  * The function computes the next temperature boundaries by browsing
176  * the trip points. The result is the closer low and high trip points
177  * to the current temperature. These values are passed to the backend
178  * driver to let it set its own notification mechanism (usually an
179  * interrupt).
180  *
181  * It does not return a value
182  */
183 void thermal_zone_set_trips(struct thermal_zone_device *tz)
184 {
185 	mutex_lock(&tz->lock);
186 	__thermal_zone_set_trips(tz);
187 	mutex_unlock(&tz->lock);
188 }
189 
190 static void thermal_cdev_set_cur_state(struct thermal_cooling_device *cdev,
191 				       int target)
192 {
193 	if (cdev->ops->set_cur_state(cdev, target))
194 		return;
195 
196 	thermal_notify_cdev_state_update(cdev->id, target);
197 	thermal_cooling_device_stats_update(cdev, target);
198 }
199 
200 void __thermal_cdev_update(struct thermal_cooling_device *cdev)
201 {
202 	struct thermal_instance *instance;
203 	unsigned long target = 0;
204 
205 	/* Make sure cdev enters the deepest cooling state */
206 	list_for_each_entry(instance, &cdev->thermal_instances, cdev_node) {
207 		dev_dbg(&cdev->device, "zone%d->target=%lu\n",
208 			instance->tz->id, instance->target);
209 		if (instance->target == THERMAL_NO_TARGET)
210 			continue;
211 		if (instance->target > target)
212 			target = instance->target;
213 	}
214 
215 	thermal_cdev_set_cur_state(cdev, target);
216 
217 	trace_cdev_update(cdev, target);
218 	dev_dbg(&cdev->device, "set to state %lu\n", target);
219 }
220 
221 /**
222  * thermal_cdev_update - update cooling device state if needed
223  * @cdev:	pointer to struct thermal_cooling_device
224  *
225  * Update the cooling device state if there is a need.
226  */
227 void thermal_cdev_update(struct thermal_cooling_device *cdev)
228 {
229 	mutex_lock(&cdev->lock);
230 	if (!cdev->updated) {
231 		__thermal_cdev_update(cdev);
232 		cdev->updated = true;
233 	}
234 	mutex_unlock(&cdev->lock);
235 }
236 
237 /**
238  * thermal_zone_get_slope - return the slope attribute of the thermal zone
239  * @tz: thermal zone device with the slope attribute
240  *
241  * Return: If the thermal zone device has a slope attribute, return it, else
242  * return 1.
243  */
244 int thermal_zone_get_slope(struct thermal_zone_device *tz)
245 {
246 	if (tz && tz->tzp)
247 		return tz->tzp->slope;
248 	return 1;
249 }
250 EXPORT_SYMBOL_GPL(thermal_zone_get_slope);
251 
252 /**
253  * thermal_zone_get_offset - return the offset attribute of the thermal zone
254  * @tz: thermal zone device with the offset attribute
255  *
256  * Return: If the thermal zone device has a offset attribute, return it, else
257  * return 0.
258  */
259 int thermal_zone_get_offset(struct thermal_zone_device *tz)
260 {
261 	if (tz && tz->tzp)
262 		return tz->tzp->offset;
263 	return 0;
264 }
265 EXPORT_SYMBOL_GPL(thermal_zone_get_offset);
266