diff options
Diffstat (limited to 'drivers/thermal/step_wise.c')
| -rw-r--r-- | drivers/thermal/step_wise.c | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/drivers/thermal/step_wise.c b/drivers/thermal/step_wise.c new file mode 100644 index 00000000000..f251521baaa --- /dev/null +++ b/drivers/thermal/step_wise.c @@ -0,0 +1,212 @@ +/* + * step_wise.c - A step-by-step Thermal throttling 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. + * + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + */ + +#include <linux/thermal.h> + +#include "thermal_core.h" + +/* + * If the temperature is higher than a trip point, + * a. if the trend is THERMAL_TREND_RAISING, use higher cooling + * state for this trip point + * b. if the trend is THERMAL_TREND_DROPPING, use lower cooling + * state for this trip point + * c. if the trend is THERMAL_TREND_RAISE_FULL, use upper limit + * for this trip point + * d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit + * for this trip point + * If the temperature is lower than a trip point, + * a. if the trend is THERMAL_TREND_RAISING, do nothing + * b. if the trend is THERMAL_TREND_DROPPING, use lower cooling + * state for this trip point, if the cooling state already + * equals lower limit, deactivate the thermal instance + * c. if the trend is THERMAL_TREND_RAISE_FULL, do nothing + * d. if the trend is THERMAL_TREND_DROP_FULL, use lower limit, + * if the cooling state already equals lower limit, + * deactive the thermal instance + */ +static unsigned long get_target_state(struct thermal_instance *instance, + enum thermal_trend trend, bool throttle) +{ + struct thermal_cooling_device *cdev = instance->cdev; + unsigned long cur_state; + unsigned long next_target; + + /* + * We keep this instance the way it is by default. + * Otherwise, we use the current state of the + * cdev in use to determine the next_target. + */ + cdev->ops->get_cur_state(cdev, &cur_state); + next_target = instance->target; + dev_dbg(&cdev->device, "cur_state=%ld\n", cur_state); + + switch (trend) { + case THERMAL_TREND_RAISING: + if (throttle) { + next_target = cur_state < instance->upper ? + (cur_state + 1) : instance->upper; + if (next_target < instance->lower) + next_target = instance->lower; + } + break; + case THERMAL_TREND_RAISE_FULL: + if (throttle) + next_target = instance->upper; + break; + case THERMAL_TREND_DROPPING: + if (cur_state == instance->lower) { + if (!throttle) + next_target = THERMAL_NO_TARGET; + } else { + next_target = cur_state - 1; + if (next_target > instance->upper) + next_target = instance->upper; + } + break; + case THERMAL_TREND_DROP_FULL: + if (cur_state == instance->lower) { + if (!throttle) + next_target = THERMAL_NO_TARGET; + } else + next_target = instance->lower; + break; + default: + break; + } + + return next_target; +} + +static void update_passive_instance(struct thermal_zone_device *tz, + enum thermal_trip_type type, int value) +{ + /* + * If value is +1, activate a passive instance. + * If value is -1, deactivate a passive instance. + */ + if (type == THERMAL_TRIP_PASSIVE || type == THERMAL_TRIPS_NONE) + tz->passive += value; +} + +static void thermal_zone_trip_update(struct thermal_zone_device *tz, int trip) +{ + long trip_temp; + enum thermal_trip_type trip_type; + enum thermal_trend trend; + struct thermal_instance *instance; + bool throttle = false; + int old_target; + + if (trip == THERMAL_TRIPS_NONE) { + trip_temp = tz->forced_passive; + trip_type = THERMAL_TRIPS_NONE; + } else { + tz->ops->get_trip_temp(tz, trip, &trip_temp); + tz->ops->get_trip_type(tz, trip, &trip_type); + } + + trend = get_tz_trend(tz, trip); + + if (tz->temperature >= trip_temp) + throttle = true; + + dev_dbg(&tz->device, "Trip%d[type=%d,temp=%ld]:trend=%d,throttle=%d\n", + trip, trip_type, trip_temp, trend, throttle); + + mutex_lock(&tz->lock); + + list_for_each_entry(instance, &tz->thermal_instances, tz_node) { + if (instance->trip != trip) + continue; + + old_target = instance->target; + instance->target = get_target_state(instance, trend, throttle); + dev_dbg(&instance->cdev->device, "old_target=%d, target=%d\n", + old_target, (int)instance->target); + + if (old_target == instance->target) + continue; + + /* Activate a passive thermal instance */ + if (old_target == THERMAL_NO_TARGET && + instance->target != THERMAL_NO_TARGET) + update_passive_instance(tz, trip_type, 1); + /* Deactivate a passive thermal instance */ + else if (old_target != THERMAL_NO_TARGET && + instance->target == THERMAL_NO_TARGET) + update_passive_instance(tz, trip_type, -1); + + + instance->cdev->updated = false; /* cdev needs update */ + } + + mutex_unlock(&tz->lock); +} + +/** + * step_wise_throttle - throttles devices asscciated with the given zone + * @tz - thermal_zone_device + * @trip - the trip point + * @trip_type - type of the trip point + * + * Throttling Logic: This uses the trend of the thermal zone to throttle. + * If the thermal zone is 'heating up' this throttles all the cooling + * devices associated with the zone and its particular trip point, by one + * step. If the zone is 'cooling down' it brings back the performance of + * the devices by one step. + */ +static int step_wise_throttle(struct thermal_zone_device *tz, int trip) +{ + struct thermal_instance *instance; + + thermal_zone_trip_update(tz, trip); + + if (tz->forced_passive) + thermal_zone_trip_update(tz, THERMAL_TRIPS_NONE); + + mutex_lock(&tz->lock); + + list_for_each_entry(instance, &tz->thermal_instances, tz_node) + thermal_cdev_update(instance->cdev); + + mutex_unlock(&tz->lock); + + return 0; +} + +static struct thermal_governor thermal_gov_step_wise = { + .name = "step_wise", + .throttle = step_wise_throttle, +}; + +int thermal_gov_step_wise_register(void) +{ + return thermal_register_governor(&thermal_gov_step_wise); +} + +void thermal_gov_step_wise_unregister(void) +{ + thermal_unregister_governor(&thermal_gov_step_wise); +} |