134 lines
3.8 KiB
C
134 lines
3.8 KiB
C
/*
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* fair_share.c - A simple weight based Thermal governor
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*
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* Copyright (C) 2012 Intel Corp
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* Copyright (C) 2012 Durgadoss R <durgadoss.r@intel.com>
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*
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
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*
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* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h>
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#include <linux/thermal.h>
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#include "thermal_core.h"
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/**
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* get_trip_level: - obtains the current trip level for a zone
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* @tz: thermal zone device
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*/
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static int get_trip_level(struct thermal_zone_device *tz)
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{
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int count = 0;
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unsigned long trip_temp;
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if (tz->trips == 0 || !tz->ops->get_trip_temp)
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return 0;
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for (count = 0; count < tz->trips; count++) {
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tz->ops->get_trip_temp(tz, count, &trip_temp);
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if (tz->temperature < trip_temp)
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break;
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}
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return count;
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}
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static long get_target_state(struct thermal_zone_device *tz,
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struct thermal_cooling_device *cdev, int weight, int level)
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{
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unsigned long max_state;
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cdev->ops->get_max_state(cdev, &max_state);
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return (long)(weight * level * max_state) / (100 * tz->trips);
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}
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/**
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* fair_share_throttle - throttles devices asscciated with the given zone
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* @tz - thermal_zone_device
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*
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* Throttling Logic: This uses three parameters to calculate the new
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* throttle state of the cooling devices associated with the given zone.
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*
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* Parameters used for Throttling:
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* P1. max_state: Maximum throttle state exposed by the cooling device.
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* P2. weight[i]/100:
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* How 'effective' the 'i'th device is, in cooling the given zone.
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* P3. cur_trip_level/max_no_of_trips:
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* This describes the extent to which the devices should be throttled.
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* We do not want to throttle too much when we trip a lower temperature,
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* whereas the throttling is at full swing if we trip critical levels.
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* (Heavily assumes the trip points are in ascending order)
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* new_state of cooling device = P3 * P2 * P1
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*/
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static int fair_share_throttle(struct thermal_zone_device *tz, int trip)
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{
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const struct thermal_zone_params *tzp;
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struct thermal_cooling_device *cdev;
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struct thermal_instance *instance;
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int i;
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int cur_trip_level = get_trip_level(tz);
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if (!tz->tzp || !tz->tzp->tbp)
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return -EINVAL;
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tzp = tz->tzp;
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for (i = 0; i < tzp->num_tbps; i++) {
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if (!tzp->tbp[i].cdev)
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continue;
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cdev = tzp->tbp[i].cdev;
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instance = get_thermal_instance(tz, cdev, trip);
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if (!instance)
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continue;
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instance->target = get_target_state(tz, cdev,
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tzp->tbp[i].weight, cur_trip_level);
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instance->cdev->updated = false;
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thermal_cdev_update(cdev);
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}
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return 0;
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}
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static struct thermal_governor thermal_gov_fair_share = {
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.name = "fair_share",
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.throttle = fair_share_throttle,
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.owner = THIS_MODULE,
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};
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static int __init thermal_gov_fair_share_init(void)
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{
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return thermal_register_governor(&thermal_gov_fair_share);
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}
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static void __exit thermal_gov_fair_share_exit(void)
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{
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thermal_unregister_governor(&thermal_gov_fair_share);
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}
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/* This should load after thermal framework */
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fs_initcall(thermal_gov_fair_share_init);
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module_exit(thermal_gov_fair_share_exit);
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MODULE_AUTHOR("Durgadoss R");
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MODULE_DESCRIPTION("A simple weight based thermal throttling governor");
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MODULE_LICENSE("GPL");
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