GNU Linux-libre 4.4.289-gnu1
[releases.git] / drivers / thermal / fair_share.c
1 /*
2  *  fair_share.c - A simple weight based Thermal 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 #include <linux/thermal.h>
26 #include <trace/events/thermal.h>
27
28 #include "thermal_core.h"
29
30 /**
31  * get_trip_level: - obtains the current trip level for a zone
32  * @tz:         thermal zone device
33  */
34 static int get_trip_level(struct thermal_zone_device *tz)
35 {
36         int count = 0;
37         int trip_temp;
38         enum thermal_trip_type trip_type;
39
40         if (tz->trips == 0 || !tz->ops->get_trip_temp)
41                 return 0;
42
43         for (count = 0; count < tz->trips; count++) {
44                 tz->ops->get_trip_temp(tz, count, &trip_temp);
45                 if (tz->temperature < trip_temp)
46                         break;
47         }
48
49         /*
50          * count > 0 only if temperature is greater than first trip
51          * point, in which case, trip_point = count - 1
52          */
53         if (count > 0) {
54                 tz->ops->get_trip_type(tz, count - 1, &trip_type);
55                 trace_thermal_zone_trip(tz, count - 1, trip_type);
56         }
57
58         return count;
59 }
60
61 static long get_target_state(struct thermal_zone_device *tz,
62                 struct thermal_cooling_device *cdev, int percentage, int level)
63 {
64         unsigned long max_state;
65
66         cdev->ops->get_max_state(cdev, &max_state);
67
68         return (long)(percentage * level * max_state) / (100 * tz->trips);
69 }
70
71 /**
72  * fair_share_throttle - throttles devices associated with the given zone
73  * @tz - thermal_zone_device
74  *
75  * Throttling Logic: This uses three parameters to calculate the new
76  * throttle state of the cooling devices associated with the given zone.
77  *
78  * Parameters used for Throttling:
79  * P1. max_state: Maximum throttle state exposed by the cooling device.
80  * P2. percentage[i]/100:
81  *      How 'effective' the 'i'th device is, in cooling the given zone.
82  * P3. cur_trip_level/max_no_of_trips:
83  *      This describes the extent to which the devices should be throttled.
84  *      We do not want to throttle too much when we trip a lower temperature,
85  *      whereas the throttling is at full swing if we trip critical levels.
86  *      (Heavily assumes the trip points are in ascending order)
87  * new_state of cooling device = P3 * P2 * P1
88  */
89 static int fair_share_throttle(struct thermal_zone_device *tz, int trip)
90 {
91         struct thermal_instance *instance;
92         int total_weight = 0;
93         int total_instance = 0;
94         int cur_trip_level = get_trip_level(tz);
95
96         mutex_lock(&tz->lock);
97
98         list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
99                 if (instance->trip != trip)
100                         continue;
101
102                 total_weight += instance->weight;
103                 total_instance++;
104         }
105
106         list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
107                 int percentage;
108                 struct thermal_cooling_device *cdev = instance->cdev;
109
110                 if (instance->trip != trip)
111                         continue;
112
113                 if (!total_weight)
114                         percentage = 100 / total_instance;
115                 else
116                         percentage = (instance->weight * 100) / total_weight;
117
118                 instance->target = get_target_state(tz, cdev, percentage,
119                                                     cur_trip_level);
120
121                 instance->cdev->updated = false;
122                 thermal_cdev_update(cdev);
123         }
124
125         mutex_unlock(&tz->lock);
126         return 0;
127 }
128
129 static struct thermal_governor thermal_gov_fair_share = {
130         .name           = "fair_share",
131         .throttle       = fair_share_throttle,
132 };
133
134 int thermal_gov_fair_share_register(void)
135 {
136         return thermal_register_governor(&thermal_gov_fair_share);
137 }
138
139 void thermal_gov_fair_share_unregister(void)
140 {
141         thermal_unregister_governor(&thermal_gov_fair_share);
142 }
143