tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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 */
34static 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
61static 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 */
89static 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 list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
97 if (instance->trip != trip)
98 continue;
99
100 total_weight += instance->weight;
101 total_instance++;
102 }
103
104 list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
105 int percentage;
106 struct thermal_cooling_device *cdev = instance->cdev;
107
108 if (instance->trip != trip)
109 continue;
110
111 if (!total_weight)
112 percentage = 100 / total_instance;
113 else
114 percentage = (instance->weight * 100) / total_weight;
115
116 instance->target = get_target_state(tz, cdev, percentage,
117 cur_trip_level);
118
119 instance->cdev->updated = false;
120 thermal_cdev_update(cdev);
121 }
122 return 0;
123}
124
125static struct thermal_governor thermal_gov_fair_share = {
126 .name = "fair_share",
127 .throttle = fair_share_throttle,
128};
129
130int thermal_gov_fair_share_register(void)
131{
132 return thermal_register_governor(&thermal_gov_fair_share);
133}
134
135void thermal_gov_fair_share_unregister(void)
136{
137 thermal_unregister_governor(&thermal_gov_fair_share);
138}
139