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/*
* fair_share.c - A simple weight based Thermal 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"
/**
* get_trip_level: - obtains the current trip level for a zone
* @tz: thermal zone device
*/
static int get_trip_level(struct thermal_zone_device *tz)
{
int count = 0;
unsigned long trip_temp;
if (tz->trips == 0 || !tz->ops->get_trip_temp)
return 0;
for (count = 0; count < tz->trips; count++) {
tz->ops->get_trip_temp(tz, count, &trip_temp);
if (tz->temperature < trip_temp)
break;
}
return count;
}
static long get_target_state(struct thermal_zone_device *tz,
struct thermal_cooling_device *cdev, int weight, int level)
{
unsigned long max_state;
cdev->ops->get_max_state(cdev, &max_state);
return (long)(weight * level * max_state) / (100 * tz->trips);
}
/**
* fair_share_throttle - throttles devices asscciated with the given zone
* @tz - thermal_zone_device
*
* Throttling Logic: This uses three parameters to calculate the new
* throttle state of the cooling devices associated with the given zone.
*
* Parameters used for Throttling:
* P1. max_state: Maximum throttle state exposed by the cooling device.
* P2. weight[i]/100:
* How 'effective' the 'i'th device is, in cooling the given zone.
* P3. cur_trip_level/max_no_of_trips:
* This describes the extent to which the devices should be throttled.
* We do not want to throttle too much when we trip a lower temperature,
* whereas the throttling is at full swing if we trip critical levels.
* (Heavily assumes the trip points are in ascending order)
* new_state of cooling device = P3 * P2 * P1
*/
static int fair_share_throttle(struct thermal_zone_device *tz, int trip)
{
const struct thermal_zone_params *tzp;
struct thermal_cooling_device *cdev;
struct thermal_instance *instance;
int i;
int cur_trip_level = get_trip_level(tz);
if (!tz->tzp || !tz->tzp->tbp)
return -EINVAL;
tzp = tz->tzp;
for (i = 0; i < tzp->num_tbps; i++) {
if (!tzp->tbp[i].cdev)
continue;
cdev = tzp->tbp[i].cdev;
instance = get_thermal_instance(tz, cdev, trip);
if (!instance)
continue;
instance->target = get_target_state(tz, cdev,
tzp->tbp[i].weight, cur_trip_level);
instance->cdev->updated = false;
thermal_cdev_update(cdev);
}
return 0;
}
static struct thermal_governor thermal_gov_fair_share = {
.name = "fair_share",
.throttle = fair_share_throttle,
.owner = THIS_MODULE,
};
static int __init thermal_gov_fair_share_init(void)
{
return thermal_register_governor(&thermal_gov_fair_share);
}
static void __exit thermal_gov_fair_share_exit(void)
{
thermal_unregister_governor(&thermal_gov_fair_share);
}
/* This should load after thermal framework */
fs_initcall(thermal_gov_fair_share_init);
module_exit(thermal_gov_fair_share_exit);
MODULE_AUTHOR("Durgadoss R");
MODULE_DESCRIPTION("A simple weight based thermal throttling governor");
MODULE_LICENSE("GPL");
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