summaryrefslogtreecommitdiff
path: root/drivers/thermal/step_wise.c
blob: 3f9cfcf66ccdfd743066cc87a71b012d4a6d36ad (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
/*
 *  step_wise.c - A step-by-step Thermal throttling governor
 *
 *  Copyright (C) 2012 Intel Corp
 *  Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com>
 *
 *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; version 2 of the License.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/thermal.h>

#include "thermal_core.h"

/*
 * If the temperature is higher than a trip point,
 *    a. if the trend is THERMAL_TREND_RAISING, use higher cooling
 *       state for this trip point
 *    b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
 *       state for this trip point
 */
static unsigned long get_target_state(struct thermal_instance *instance,
					enum thermal_trend trend)
{
	struct thermal_cooling_device *cdev = instance->cdev;
	unsigned long cur_state;

	cdev->ops->get_cur_state(cdev, &cur_state);

	if (trend == THERMAL_TREND_RAISING) {
		cur_state = cur_state < instance->upper ?
			    (cur_state + 1) : instance->upper;
	} else if (trend == THERMAL_TREND_DROPPING) {
		cur_state = cur_state > instance->lower ?
			    (cur_state - 1) : instance->lower;
	}

	return cur_state;
}

static void update_passive_instance(struct thermal_zone_device *tz,
				enum thermal_trip_type type, int value)
{
	/*
	 * If value is +1, activate a passive instance.
	 * If value is -1, deactivate a passive instance.
	 */
	if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE)
		tz->passive += value;
}

static void update_instance_for_throttle(struct thermal_zone_device *tz,
				int trip, enum thermal_trip_type trip_type,
				enum thermal_trend trend)
{
	struct thermal_instance *instance;

	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
		if (instance->trip != trip)
			continue;

		instance->target = get_target_state(instance, trend);

		/* Activate a passive thermal instance */
		if (instance->target == THERMAL_NO_TARGET)
			update_passive_instance(tz, trip_type, 1);

		instance->cdev->updated = false; /* cdev needs update */
	}
}

static void update_instance_for_dethrottle(struct thermal_zone_device *tz,
				int trip, enum thermal_trip_type trip_type)
{
	struct thermal_instance *instance;
	struct thermal_cooling_device *cdev;
	unsigned long cur_state;

	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
		if (instance->trip != trip ||
			instance->target == THERMAL_NO_TARGET)
			continue;

		cdev = instance->cdev;
		cdev->ops->get_cur_state(cdev, &cur_state);

		instance->target = cur_state > instance->lower ?
			    (cur_state - 1) : THERMAL_NO_TARGET;

		/* Deactivate a passive thermal instance */
		if (instance->target == THERMAL_NO_TARGET)
			update_passive_instance(tz, trip_type, -1);

		cdev->updated = false; /* cdev needs update */
	}
}

static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
{
	long trip_temp;
	enum thermal_trip_type trip_type;
	enum thermal_trend trend;

	if (trip == THERMAL_TRIPS_NONE) {
		trip_temp = tz->forced_passive;
		trip_type = THERMAL_TRIPS_NONE;
	} else {
		tz->ops->get_trip_temp(tz, trip, &trip_temp);
		tz->ops->get_trip_type(tz, trip, &trip_type);
	}

	trend = get_tz_trend(tz, trip);

	mutex_lock(&tz->lock);

	if (tz->temperature >= trip_temp)
		update_instance_for_throttle(tz, trip, trip_type, trend);
	else
		update_instance_for_dethrottle(tz, trip, trip_type);

	mutex_unlock(&tz->lock);
}

/**
 * step_wise_throttle - throttles devices asscciated with the given zone
 * @tz - thermal_zone_device
 * @trip - the trip point
 * @trip_type - type of the trip point
 *
 * Throttling Logic: This uses the trend of the thermal zone to throttle.
 * If the thermal zone is 'heating up' this throttles all the cooling
 * devices associated with the zone and its particular trip point, by one
 * step. If the zone is 'cooling down' it brings back the performance of
 * the devices by one step.
 */
int step_wise_throttle(struct thermal_zone_device *tz, int trip)
{
	struct thermal_instance *instance;

	thermal_zone_trip_update(tz, trip);

	if (tz->forced_passive)
		thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);

	mutex_lock(&tz->lock);

	list_for_each_entry(instance, &tz->thermal_instances, tz_node)
		thermal_cdev_update(instance->cdev);

	mutex_unlock(&tz->lock);

	return 0;
}

struct thermal_governor thermal_gov_step_wise = {
	.name		= DEFAULT_THERMAL_GOVERNOR,
	.throttle	= step_wise_throttle,
	.owner		= THIS_MODULE,
};

static int __init thermal_gov_step_wise_init(void)
{
	return thermal_register_governor(&thermal_gov_step_wise);
}

static void __exit thermal_gov_step_wise_exit(void)
{
	thermal_unregister_governor(&thermal_gov_step_wise);
}

/* This should load after thermal framework */
fs_initcall(thermal_gov_step_wise_init);
module_exit(thermal_gov_step_wise_exit);

MODULE_AUTHOR("Durgadoss R");
MODULE_DESCRIPTION("A step-by-step thermal throttling governor");
MODULE_LICENSE("GPL");