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 EXPORT_SYMBOL(get_tz_trend);
43 
44 struct thermal_instance *
45 get_thermal_instance(struct thermal_zone_device *tz,
46 		     struct thermal_cooling_device *cdev, int trip)
47 {
48 	struct thermal_instance *pos = NULL;
49 	struct thermal_instance *target_instance = NULL;
50 
51 	mutex_lock(&tz->lock);
52 	mutex_lock(&cdev->lock);
53 
54 	list_for_each_entry(pos, &tz->thermal_instances, tz_node) {
55 		if (pos->tz == tz && pos->trip == trip && pos->cdev == cdev) {
56 			target_instance = pos;
57 			break;
58 		}
59 	}
60 
61 	mutex_unlock(&cdev->lock);
62 	mutex_unlock(&tz->lock);
63 
64 	return target_instance;
65 }
66 EXPORT_SYMBOL(get_thermal_instance);
67 
68 /**
69  * thermal_zone_get_temp() - returns the temperature of a thermal zone
70  * @tz: a valid pointer to a struct thermal_zone_device
71  * @temp: a valid pointer to where to store the resulting temperature.
72  *
73  * When a valid thermal zone reference is passed, it will fetch its
74  * temperature and fill @temp.
75  *
76  * Return: On success returns 0, an error code otherwise
77  */
78 int thermal_zone_get_temp(struct thermal_zone_device *tz, int *temp)
79 {
80 	int ret = -EINVAL;
81 	int count;
82 	int crit_temp = INT_MAX;
83 	enum thermal_trip_type type;
84 
85 	if (!tz || IS_ERR(tz) || !tz->ops->get_temp)
86 		goto exit;
87 
88 	mutex_lock(&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->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 	mutex_unlock(&tz->lock);
112 exit:
113 	return ret;
114 }
115 EXPORT_SYMBOL_GPL(thermal_zone_get_temp);
116 
117 /**
118  * thermal_zone_set_trips - Computes the next trip points for the driver
119  * @tz: a pointer to a thermal zone device structure
120  *
121  * The function computes the next temperature boundaries by browsing
122  * the trip points. The result is the closer low and high trip points
123  * to the current temperature. These values are passed to the backend
124  * driver to let it set its own notification mechanism (usually an
125  * interrupt).
126  *
127  * It does not return a value
128  */
129 void thermal_zone_set_trips(struct thermal_zone_device *tz)
130 {
131 	int low = -INT_MAX;
132 	int high = INT_MAX;
133 	int trip_temp, hysteresis;
134 	int i, ret;
135 
136 	mutex_lock(&tz->lock);
137 
138 	if (!tz->ops->set_trips || !tz->ops->get_trip_hyst)
139 		goto exit;
140 
141 	for (i = 0; i < tz->trips; i++) {
142 		int trip_low;
143 
144 		tz->ops->get_trip_temp(tz, i, &trip_temp);
145 		tz->ops->get_trip_hyst(tz, i, &hysteresis);
146 
147 		trip_low = trip_temp - hysteresis;
148 
149 		if (trip_low < tz->temperature && trip_low > low)
150 			low = trip_low;
151 
152 		if (trip_temp > tz->temperature && trip_temp < high)
153 			high = trip_temp;
154 	}
155 
156 	/* No need to change trip points */
157 	if (tz->prev_low_trip == low && tz->prev_high_trip == high)
158 		goto exit;
159 
160 	tz->prev_low_trip = low;
161 	tz->prev_high_trip = high;
162 
163 	dev_dbg(&tz->device,
164 		"new temperature boundaries: %d < x < %d\n", low, high);
165 
166 	/*
167 	 * Set a temperature window. When this window is left the driver
168 	 * must inform the thermal core via thermal_zone_device_update.
169 	 */
170 	ret = tz->ops->set_trips(tz, low, high);
171 	if (ret)
172 		dev_err(&tz->device, "Failed to set trips: %d\n", ret);
173 
174 exit:
175 	mutex_unlock(&tz->lock);
176 }
177 
178 void thermal_cdev_update(struct thermal_cooling_device *cdev)
179 {
180 	struct thermal_instance *instance;
181 	unsigned long target = 0;
182 
183 	mutex_lock(&cdev->lock);
184 	/* cooling device is updated*/
185 	if (cdev->updated) {
186 		mutex_unlock(&cdev->lock);
187 		return;
188 	}
189 
190 	/* Make sure cdev enters the deepest cooling state */
191 	list_for_each_entry(instance, &cdev->thermal_instances, cdev_node) {
192 		dev_dbg(&cdev->device, "zone%d->target=%lu\n",
193 			instance->tz->id, instance->target);
194 		if (instance->target == THERMAL_NO_TARGET)
195 			continue;
196 		if (instance->target > target)
197 			target = instance->target;
198 	}
199 
200 	if (!cdev->ops->set_cur_state(cdev, target))
201 		thermal_cooling_device_stats_update(cdev, target);
202 
203 	cdev->updated = true;
204 	mutex_unlock(&cdev->lock);
205 	trace_cdev_update(cdev, target);
206 	dev_dbg(&cdev->device, "set to state %lu\n", target);
207 }
208 EXPORT_SYMBOL(thermal_cdev_update);
209 
210 /**
211  * thermal_zone_get_slope - return the slope attribute of the thermal zone
212  * @tz: thermal zone device with the slope attribute
213  *
214  * Return: If the thermal zone device has a slope attribute, return it, else
215  * return 1.
216  */
217 int thermal_zone_get_slope(struct thermal_zone_device *tz)
218 {
219 	if (tz && tz->tzp)
220 		return tz->tzp->slope;
221 	return 1;
222 }
223 EXPORT_SYMBOL_GPL(thermal_zone_get_slope);
224 
225 /**
226  * thermal_zone_get_offset - return the offset attribute of the thermal zone
227  * @tz: thermal zone device with the offset attribute
228  *
229  * Return: If the thermal zone device has a offset attribute, return it, else
230  * return 0.
231  */
232 int thermal_zone_get_offset(struct thermal_zone_device *tz)
233 {
234 	if (tz && tz->tzp)
235 		return tz->tzp->offset;
236 	return 0;
237 }
238 EXPORT_SYMBOL_GPL(thermal_zone_get_offset);
239