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	unsigned long 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 weight, int level)
63{
64	unsigned long max_state;
65
66	cdev->ops->get_max_state(cdev, &max_state);
67
68	return (long)(weight * level * max_state) / (100 * tz->trips);
69}
70
71/**
72 * fair_share_throttle - throttles devices asscciated 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. weight[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	const struct thermal_zone_params *tzp;
92	struct thermal_cooling_device *cdev;
93	struct thermal_instance *instance;
94	int i;
95	int cur_trip_level = get_trip_level(tz);
96
97	if (!tz->tzp || !tz->tzp->tbp)
98		return -EINVAL;
99
100	tzp = tz->tzp;
101
102	for (i = 0; i < tzp->num_tbps; i++) {
103		if (!tzp->tbp[i].cdev)
104			continue;
105
106		cdev = tzp->tbp[i].cdev;
107		instance = get_thermal_instance(tz, cdev, trip);
108		if (!instance)
109			continue;
110
111		instance->target = get_target_state(tz, cdev,
112					tzp->tbp[i].weight, cur_trip_level);
113
114		instance->cdev->updated = false;
115		thermal_cdev_update(cdev);
116	}
117	return 0;
118}
119
120static struct thermal_governor thermal_gov_fair_share = {
121	.name		= "fair_share",
122	.throttle	= fair_share_throttle,
123};
124
125int thermal_gov_fair_share_register(void)
126{
127	return thermal_register_governor(&thermal_gov_fair_share);
128}
129
130void thermal_gov_fair_share_unregister(void)
131{
132	thermal_unregister_governor(&thermal_gov_fair_share);
133}
134
135