Thermal: Allow first cooling device update
[linux-2.6.git] / drivers / thermal / step_wise.c
1 /*
2  *  step_wise.c - A step-by-step Thermal throttling governor
3  *
4  *  Copyright (C) 2012 Intel Corp
5  *  Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com>
6  *
7  *  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
8  *
9  *  This program is free software; you can redistribute it and/or modify
10  *  it under the terms of the GNU General Public License as published by
11  *  the Free Software Foundation; version 2 of the License.
12  *
13  *  This program is distributed in the hope that it will be useful, but
14  *  WITHOUT ANY WARRANTY; without even the implied warranty of
15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16  *  General Public License for more details.
17  *
18  *  You should have received a copy of the GNU General Public License along
19  *  with this program; if not, write to the Free Software Foundation, Inc.,
20  *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
21  *
22  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
23  */
24
25 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
26
27 #include <linux/module.h>
28 #include <linux/thermal.h>
29
30 #include "thermal_core.h"
31
32 /*
33  * If the temperature is higher than a trip point,
34  *    a. if the trend is THERMAL_TREND_RAISING, use higher cooling
35  *       state for this trip point
36  *    b. if the trend is THERMAL_TREND_DROPPING, use lower cooling
37  *       state for this trip point
38  */
39 static unsigned long get_target_state(struct thermal_instance *instance,
40                                         enum thermal_trend trend)
41 {
42         struct thermal_cooling_device *cdev = instance->cdev;
43         unsigned long cur_state;
44
45         cdev->ops->get_cur_state(cdev, &cur_state);
46
47         if (trend == THERMAL_TREND_RAISING) {
48                 cur_state = cur_state < instance->upper ?
49                             (cur_state + 1) : instance->upper;
50         } else if (trend == THERMAL_TREND_DROPPING) {
51                 cur_state = cur_state > instance->lower ?
52                             (cur_state - 1) : instance->lower;
53         }
54
55         return cur_state;
56 }
57
58 static void update_passive_instance(struct thermal_zone_device *tz,
59                                 enum thermal_trip_type type, int value)
60 {
61         /*
62          * If value is +1, activate a passive instance.
63          * If value is -1, deactivate a passive instance.
64          */
65         if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE)
66                 tz->passive += value;
67 }
68
69 static void update_instance_for_throttle(struct thermal_zone_device *tz,
70                                 int trip, enum thermal_trip_type trip_type,
71                                 enum thermal_trend trend)
72 {
73         struct thermal_instance *instance;
74         unsigned long old_target;
75
76         list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
77                 if (instance->trip != trip)
78                         continue;
79
80                 old_target = instance->target;
81                 instance->target = get_target_state(instance, trend);
82
83                 /* Activate a passive thermal instance */
84                 if (old_target == THERMAL_NO_TARGET &&
85                         instance->target != THERMAL_NO_TARGET)
86                         update_passive_instance(tz, trip_type, 1);
87
88                 instance->cdev->updated = false; /* cdev needs update */
89         }
90 }
91
92 static void update_instance_for_dethrottle(struct thermal_zone_device *tz,
93                                 int trip, enum thermal_trip_type trip_type)
94 {
95         struct thermal_instance *instance;
96         struct thermal_cooling_device *cdev;
97         unsigned long cur_state;
98         unsigned long old_target;
99
100         list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
101                 if (instance->trip != trip ||
102                         instance->target == THERMAL_NO_TARGET)
103                         continue;
104
105                 cdev = instance->cdev;
106                 cdev->ops->get_cur_state(cdev, &cur_state);
107
108                 old_target = instance->target;
109                 instance->target = cur_state > instance->lower ?
110                             (cur_state - 1) : THERMAL_NO_TARGET;
111
112                 /* Deactivate a passive thermal instance */
113                 if (old_target != THERMAL_NO_TARGET &&
114                         instance->target == THERMAL_NO_TARGET)
115                         update_passive_instance(tz, trip_type, -1);
116
117                 cdev->updated = false; /* cdev needs update */
118         }
119 }
120
121 static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip)
122 {
123         long trip_temp;
124         enum thermal_trip_type trip_type;
125         enum thermal_trend trend;
126
127         if (trip == THERMAL_TRIPS_NONE) {
128                 trip_temp = tz->forced_passive;
129                 trip_type = THERMAL_TRIPS_NONE;
130         } else {
131                 tz->ops->get_trip_temp(tz, trip, &trip_temp);
132                 tz->ops->get_trip_type(tz, trip, &trip_type);
133         }
134
135         trend = get_tz_trend(tz, trip);
136
137         mutex_lock(&tz->lock);
138
139         if (tz->temperature >= trip_temp)
140                 update_instance_for_throttle(tz, trip, trip_type, trend);
141         else
142                 update_instance_for_dethrottle(tz, trip, trip_type);
143
144         mutex_unlock(&tz->lock);
145 }
146
147 /**
148  * step_wise_throttle - throttles devices asscciated with the given zone
149  * @tz - thermal_zone_device
150  * @trip - the trip point
151  * @trip_type - type of the trip point
152  *
153  * Throttling Logic: This uses the trend of the thermal zone to throttle.
154  * If the thermal zone is 'heating up' this throttles all the cooling
155  * devices associated with the zone and its particular trip point, by one
156  * step. If the zone is 'cooling down' it brings back the performance of
157  * the devices by one step.
158  */
159 static int step_wise_throttle(struct thermal_zone_device *tz, int trip)
160 {
161         struct thermal_instance *instance;
162
163         thermal_zone_trip_update(tz, trip);
164
165         if (tz->forced_passive)
166                 thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE);
167
168         mutex_lock(&tz->lock);
169
170         list_for_each_entry(instance, &tz->thermal_instances, tz_node)
171                 thermal_cdev_update(instance->cdev);
172
173         mutex_unlock(&tz->lock);
174
175         return 0;
176 }
177
178 static struct thermal_governor thermal_gov_step_wise = {
179         .name           = DEFAULT_THERMAL_GOVERNOR,
180         .throttle       = step_wise_throttle,
181         .owner          = THIS_MODULE,
182 };
183
184 static int __init thermal_gov_step_wise_init(void)
185 {
186         return thermal_register_governor(&thermal_gov_step_wise);
187 }
188
189 static void __exit thermal_gov_step_wise_exit(void)
190 {
191         thermal_unregister_governor(&thermal_gov_step_wise);
192 }
193
194 /* This should load after thermal framework */
195 fs_initcall(thermal_gov_step_wise_init);
196 module_exit(thermal_gov_step_wise_exit);
197
198 MODULE_AUTHOR("Durgadoss R");
199 MODULE_DESCRIPTION("A step-by-step thermal throttling governor");
200 MODULE_LICENSE("GPL");