| /* |
| * A power allocator to manage temperature |
| * |
| * Copyright (C) 2014 ARM Ltd. |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| * |
| * This program is distributed "as is" WITHOUT ANY WARRANTY of any |
| * kind, whether express or implied; without even the implied warranty |
| * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| */ |
| |
| #define pr_fmt(fmt) "Power allocator: " fmt |
| |
| #include <linux/ratelimit.h> |
| #include <linux/rculist.h> |
| #include <linux/slab.h> |
| #include <linux/thermal.h> |
| |
| #define CREATE_TRACE_POINTS |
| #include <trace/events/thermal_power_allocator.h> |
| |
| #include "thermal_core.h" |
| |
| #define INVALID_TRIP -1 |
| |
| #define FRAC_BITS 10 |
| #define int_to_frac(x) ((x) << FRAC_BITS) |
| #define frac_to_int(x) ((x) >> FRAC_BITS) |
| |
| DEFINE_RATELIMIT_STATE(power_allocator_ratelimit_state, 30 * HZ, 1); |
| |
| static int power_allocator_ratelimit(void) |
| { |
| return __ratelimit(&power_allocator_ratelimit_state); |
| } |
| |
| /** |
| * mul_frac() - multiply two fixed-point numbers |
| * @x: first multiplicand |
| * @y: second multiplicand |
| * |
| * Return: the result of multiplying two fixed-point numbers. The |
| * result is also a fixed-point number. |
| */ |
| static inline s64 mul_frac(s64 x, s64 y) |
| { |
| return (x * y) >> FRAC_BITS; |
| } |
| |
| /** |
| * div_frac() - divide two fixed-point numbers |
| * @x: the dividend |
| * @y: the divisor |
| * |
| * Return: the result of dividing two fixed-point numbers. The |
| * result is also a fixed-point number. |
| */ |
| static inline s64 div_frac(s64 x, s64 y) |
| { |
| return div_s64(x << FRAC_BITS, y); |
| } |
| |
| /** |
| * struct power_allocator_params - parameters for the power allocator governor |
| * @allocated_tzp: whether we have allocated tzp for this thermal zone and |
| * it needs to be freed on unbind |
| * @err_integral: accumulated error in the PID controller. |
| * @prev_err: error in the previous iteration of the PID controller. |
| * Used to calculate the derivative term. |
| * @trip_switch_on: first passive trip point of the thermal zone. The |
| * governor switches on when this trip point is crossed. |
| * If the thermal zone only has one passive trip point, |
| * @trip_switch_on should be INVALID_TRIP. |
| * @trip_max_desired_temperature: last passive trip point of the thermal |
| * zone. The temperature we are |
| * controlling for. |
| */ |
| struct power_allocator_params { |
| bool allocated_tzp; |
| s64 err_integral; |
| s32 prev_err; |
| int trip_switch_on; |
| int trip_max_desired_temperature; |
| }; |
| |
| /** |
| * estimate_sustainable_power() - Estimate the sustainable power of a thermal zone |
| * @tz: thermal zone we are operating in |
| * |
| * For thermal zones that don't provide a sustainable_power in their |
| * thermal_zone_params, estimate one. Calculate it using the minimum |
| * power of all the cooling devices as that gives a valid value that |
| * can give some degree of functionality. For optimal performance of |
| * this governor, provide a sustainable_power in the thermal zone's |
| * thermal_zone_params. |
| */ |
| static u32 estimate_sustainable_power(struct thermal_zone_device *tz) |
| { |
| u32 sustainable_power = 0; |
| struct thermal_instance *instance; |
| struct power_allocator_params *params = tz->governor_data; |
| |
| list_for_each_entry(instance, &tz->thermal_instances, tz_node) { |
| struct thermal_cooling_device *cdev = instance->cdev; |
| u32 min_power; |
| |
| if (instance->trip != params->trip_max_desired_temperature) |
| continue; |
| |
| if (power_actor_get_min_power(cdev, tz, &min_power)) |
| continue; |
| |
| sustainable_power += min_power; |
| } |
| |
| return sustainable_power; |
| } |
| |
| /** |
| * estimate_pid_constants() - Estimate the constants for the PID controller |
| * @tz: thermal zone for which to estimate the constants |
| * @sustainable_power: sustainable power for the thermal zone |
| * @trip_switch_on: trip point number for the switch on temperature |
| * @control_temp: target temperature for the power allocator governor |
| * @force: whether to force the update of the constants |
| * |
| * This function is used to update the estimation of the PID |
| * controller constants in struct thermal_zone_parameters. |
| * Sustainable power is provided in case it was estimated. The |
| * estimated sustainable_power should not be stored in the |
| * thermal_zone_parameters so it has to be passed explicitly to this |
| * function. |
| * |
| * If @force is not set, the values in the thermal zone's parameters |
| * are preserved if they are not zero. If @force is set, the values |
| * in thermal zone's parameters are overwritten. |
| */ |
| static void estimate_pid_constants(struct thermal_zone_device *tz, |
| u32 sustainable_power, int trip_switch_on, |
| int control_temp, bool force) |
| { |
| int ret; |
| int switch_on_temp; |
| u32 temperature_threshold; |
| |
| ret = tz->ops->get_trip_temp(tz, trip_switch_on, &switch_on_temp); |
| if (ret) |
| switch_on_temp = 0; |
| |
| temperature_threshold = control_temp - switch_on_temp; |
| /* |
| * estimate_pid_constants() tries to find appropriate default |
| * values for thermal zones that don't provide them. If a |
| * system integrator has configured a thermal zone with two |
| * passive trip points at the same temperature, that person |
| * hasn't put any effort to set up the thermal zone properly |
| * so just give up. |
| */ |
| if (!temperature_threshold) |
| return; |
| |
| if (!tz->tzp->k_po || force) |
| tz->tzp->k_po = int_to_frac(sustainable_power) / |
| temperature_threshold; |
| |
| if (!tz->tzp->k_pu || force) |
| tz->tzp->k_pu = int_to_frac(2 * sustainable_power) / |
| temperature_threshold; |
| |
| if (!tz->tzp->k_i || force) |
| tz->tzp->k_i = int_to_frac(10) / 1000; |
| /* |
| * The default for k_d and integral_cutoff is 0, so we can |
| * leave them as they are. |
| */ |
| } |
| |
| /** |
| * pid_controller() - PID controller |
| * @tz: thermal zone we are operating in |
| * @control_temp: the target temperature in millicelsius |
| * @max_allocatable_power: maximum allocatable power for this thermal zone |
| * |
| * This PID controller increases the available power budget so that the |
| * temperature of the thermal zone gets as close as possible to |
| * @control_temp and limits the power if it exceeds it. k_po is the |
| * proportional term when we are overshooting, k_pu is the |
| * proportional term when we are undershooting. integral_cutoff is a |
| * threshold below which we stop accumulating the error. The |
| * accumulated error is only valid if the requested power will make |
| * the system warmer. If the system is mostly idle, there's no point |
| * in accumulating positive error. |
| * |
| * Return: The power budget for the next period. |
| */ |
| static u32 pid_controller(struct thermal_zone_device *tz, |
| int control_temp, |
| u32 max_allocatable_power) |
| { |
| s64 p, i, d, power_range; |
| s32 err, max_power_frac; |
| u32 sustainable_power; |
| struct power_allocator_params *params = tz->governor_data; |
| |
| max_power_frac = int_to_frac(max_allocatable_power); |
| |
| if (tz->tzp->sustainable_power) { |
| sustainable_power = tz->tzp->sustainable_power; |
| } else { |
| sustainable_power = estimate_sustainable_power(tz); |
| estimate_pid_constants(tz, sustainable_power, |
| params->trip_switch_on, control_temp, |
| true); |
| } |
| |
| err = control_temp - tz->temperature; |
| err = int_to_frac(err); |
| |
| /* Calculate the proportional term */ |
| p = mul_frac(err < 0 ? tz->tzp->k_po : tz->tzp->k_pu, err); |
| |
| /* |
| * Calculate the integral term |
| * |
| * if the error is less than cut off allow integration (but |
| * the integral is limited to max power) |
| */ |
| i = mul_frac(tz->tzp->k_i, params->err_integral); |
| |
| if (err < int_to_frac(tz->tzp->integral_cutoff)) { |
| s64 i_next = i + mul_frac(tz->tzp->k_i, err); |
| |
| if (abs(i_next) < max_power_frac) { |
| i = i_next; |
| params->err_integral += err; |
| } |
| } |
| |
| /* |
| * Calculate the derivative term |
| * |
| * We do err - prev_err, so with a positive k_d, a decreasing |
| * error (i.e. driving closer to the line) results in less |
| * power being applied, slowing down the controller) |
| */ |
| d = mul_frac(tz->tzp->k_d, err - params->prev_err); |
| d = div_frac(d, tz->passive_delay); |
| params->prev_err = err; |
| |
| power_range = p + i + d; |
| |
| /* feed-forward the known sustainable dissipatable power */ |
| power_range = sustainable_power + frac_to_int(power_range); |
| |
| power_range = clamp(power_range, (s64)0, (s64)max_allocatable_power); |
| |
| trace_thermal_power_allocator_pid(tz, frac_to_int(err), |
| frac_to_int(params->err_integral), |
| frac_to_int(p), frac_to_int(i), |
| frac_to_int(d), power_range); |
| |
| return power_range; |
| } |
| |
| /** |
| * divvy_up_power() - divvy the allocated power between the actors |
| * @req_power: each actor's requested power |
| * @max_power: each actor's maximum available power |
| * @num_actors: size of the @req_power, @max_power and @granted_power's array |
| * @total_req_power: sum of @req_power |
| * @power_range: total allocated power |
| * @granted_power: output array: each actor's granted power |
| * @extra_actor_power: an appropriately sized array to be used in the |
| * function as temporary storage of the extra power given |
| * to the actors |
| * |
| * This function divides the total allocated power (@power_range) |
| * fairly between the actors. It first tries to give each actor a |
| * share of the @power_range according to how much power it requested |
| * compared to the rest of the actors. For example, if only one actor |
| * requests power, then it receives all the @power_range. If |
| * three actors each requests 1mW, each receives a third of the |
| * @power_range. |
| * |
| * If any actor received more than their maximum power, then that |
| * surplus is re-divvied among the actors based on how far they are |
| * from their respective maximums. |
| * |
| * Granted power for each actor is written to @granted_power, which |
| * should've been allocated by the calling function. |
| */ |
| static void divvy_up_power(u32 *req_power, u32 *max_power, int num_actors, |
| u32 total_req_power, u32 power_range, |
| u32 *granted_power, u32 *extra_actor_power) |
| { |
| u32 extra_power, capped_extra_power; |
| int i; |
| |
| /* |
| * Prevent division by 0 if none of the actors request power. |
| */ |
| if (!total_req_power) |
| total_req_power = 1; |
| |
| capped_extra_power = 0; |
| extra_power = 0; |
| for (i = 0; i < num_actors; i++) { |
| u64 req_range = (u64)req_power[i] * power_range; |
| |
| granted_power[i] = DIV_ROUND_CLOSEST_ULL(req_range, |
| total_req_power); |
| |
| if (granted_power[i] > max_power[i]) { |
| extra_power += granted_power[i] - max_power[i]; |
| granted_power[i] = max_power[i]; |
| } |
| |
| extra_actor_power[i] = max_power[i] - granted_power[i]; |
| capped_extra_power += extra_actor_power[i]; |
| } |
| |
| if (!extra_power) |
| return; |
| |
| /* |
| * Re-divvy the reclaimed extra among actors based on |
| * how far they are from the max |
| */ |
| extra_power = min(extra_power, capped_extra_power); |
| if (capped_extra_power > 0) |
| for (i = 0; i < num_actors; i++) |
| granted_power[i] += (extra_actor_power[i] * |
| extra_power) / capped_extra_power; |
| } |
| |
| static int allocate_power(struct thermal_zone_device *tz, |
| int control_temp) |
| { |
| struct thermal_instance *instance; |
| struct power_allocator_params *params = tz->governor_data; |
| u32 *req_power, *max_power, *granted_power, *extra_actor_power; |
| u32 *weighted_req_power; |
| u32 total_req_power, max_allocatable_power, total_weighted_req_power; |
| u32 total_granted_power, power_range; |
| int i, num_actors, total_weight, ret = 0; |
| int trip_max_desired_temperature = params->trip_max_desired_temperature; |
| |
| mutex_lock(&tz->lock); |
| |
| num_actors = 0; |
| total_weight = 0; |
| list_for_each_entry(instance, &tz->thermal_instances, tz_node) { |
| if ((instance->trip == trip_max_desired_temperature) && |
| cdev_is_power_actor(instance->cdev)) { |
| num_actors++; |
| total_weight += instance->weight; |
| } |
| } |
| |
| if (!num_actors) { |
| ret = -ENODEV; |
| goto unlock; |
| } |
| |
| /* |
| * We need to allocate five arrays of the same size: |
| * req_power, max_power, granted_power, extra_actor_power and |
| * weighted_req_power. They are going to be needed until this |
| * function returns. Allocate them all in one go to simplify |
| * the allocation and deallocation logic. |
| */ |
| BUILD_BUG_ON(sizeof(*req_power) != sizeof(*max_power)); |
| BUILD_BUG_ON(sizeof(*req_power) != sizeof(*granted_power)); |
| BUILD_BUG_ON(sizeof(*req_power) != sizeof(*extra_actor_power)); |
| BUILD_BUG_ON(sizeof(*req_power) != sizeof(*weighted_req_power)); |
| req_power = kcalloc(num_actors * 5, sizeof(*req_power), GFP_KERNEL); |
| if (!req_power) { |
| ret = -ENOMEM; |
| goto unlock; |
| } |
| |
| max_power = &req_power[num_actors]; |
| granted_power = &req_power[2 * num_actors]; |
| extra_actor_power = &req_power[3 * num_actors]; |
| weighted_req_power = &req_power[4 * num_actors]; |
| |
| i = 0; |
| total_weighted_req_power = 0; |
| total_req_power = 0; |
| max_allocatable_power = 0; |
| |
| list_for_each_entry(instance, &tz->thermal_instances, tz_node) { |
| int weight; |
| struct thermal_cooling_device *cdev = instance->cdev; |
| |
| if (instance->trip != trip_max_desired_temperature) |
| continue; |
| |
| if (!cdev_is_power_actor(cdev)) |
| continue; |
| |
| if (cdev->ops->get_requested_power(cdev, tz, &req_power[i])) |
| continue; |
| |
| if (!total_weight) |
| weight = 1 << FRAC_BITS; |
| else |
| weight = instance->weight; |
| |
| weighted_req_power[i] = frac_to_int(weight * req_power[i]); |
| |
| if (power_actor_get_max_power(cdev, tz, &max_power[i])) |
| continue; |
| |
| total_req_power += req_power[i]; |
| max_allocatable_power += max_power[i]; |
| total_weighted_req_power += weighted_req_power[i]; |
| |
| i++; |
| } |
| |
| power_range = pid_controller(tz, control_temp, max_allocatable_power); |
| |
| divvy_up_power(weighted_req_power, max_power, num_actors, |
| total_weighted_req_power, power_range, granted_power, |
| extra_actor_power); |
| |
| total_granted_power = 0; |
| i = 0; |
| list_for_each_entry(instance, &tz->thermal_instances, tz_node) { |
| if (instance->trip != trip_max_desired_temperature) |
| continue; |
| |
| if (!cdev_is_power_actor(instance->cdev)) |
| continue; |
| |
| power_actor_set_power(instance->cdev, instance, |
| granted_power[i]); |
| total_granted_power += granted_power[i]; |
| |
| i++; |
| } |
| |
| trace_thermal_power_allocator(tz, req_power, total_req_power, |
| granted_power, total_granted_power, |
| num_actors, power_range, |
| max_allocatable_power, tz->temperature, |
| control_temp - tz->temperature); |
| |
| if (total_granted_power < total_req_power && |
| power_allocator_ratelimit()) { |
| dev_info(&tz->device, "Controlling power: control_temp=%d " |
| "last_temp=%d, curr_temp=%d total_requested_power=%d " |
| "total_granted_power=%d\n", control_temp, |
| tz->last_temperature, tz->temperature, |
| total_req_power, total_granted_power); |
| } |
| |
| kfree(req_power); |
| unlock: |
| mutex_unlock(&tz->lock); |
| |
| return ret; |
| } |
| |
| /** |
| * get_governor_trips() - get the number of the two trip points that are key for this governor |
| * @tz: thermal zone to operate on |
| * @params: pointer to private data for this governor |
| * |
| * The power allocator governor works optimally with two trips points: |
| * a "switch on" trip point and a "maximum desired temperature". These |
| * are defined as the first and last passive trip points. |
| * |
| * If there is only one trip point, then that's considered to be the |
| * "maximum desired temperature" trip point and the governor is always |
| * on. If there are no passive or active trip points, then the |
| * governor won't do anything. In fact, its throttle function |
| * won't be called at all. |
| */ |
| static void get_governor_trips(struct thermal_zone_device *tz, |
| struct power_allocator_params *params) |
| { |
| int i, last_active, last_passive; |
| bool found_first_passive; |
| |
| found_first_passive = false; |
| last_active = INVALID_TRIP; |
| last_passive = INVALID_TRIP; |
| |
| for (i = 0; i < tz->trips; i++) { |
| enum thermal_trip_type type; |
| int ret; |
| |
| ret = tz->ops->get_trip_type(tz, i, &type); |
| if (ret) { |
| dev_warn(&tz->device, |
| "Failed to get trip point %d type: %d\n", i, |
| ret); |
| continue; |
| } |
| |
| if (type == THERMAL_TRIP_PASSIVE) { |
| if (!found_first_passive) { |
| params->trip_switch_on = i; |
| found_first_passive = true; |
| } else { |
| last_passive = i; |
| } |
| } else if (type == THERMAL_TRIP_ACTIVE) { |
| last_active = i; |
| } else { |
| break; |
| } |
| } |
| |
| if (last_passive != INVALID_TRIP) { |
| params->trip_max_desired_temperature = last_passive; |
| } else if (found_first_passive) { |
| params->trip_max_desired_temperature = params->trip_switch_on; |
| params->trip_switch_on = INVALID_TRIP; |
| } else { |
| params->trip_switch_on = INVALID_TRIP; |
| params->trip_max_desired_temperature = last_active; |
| } |
| } |
| |
| static void reset_pid_controller(struct power_allocator_params *params) |
| { |
| params->err_integral = 0; |
| params->prev_err = 0; |
| } |
| |
| static void allow_maximum_power(struct thermal_zone_device *tz) |
| { |
| struct thermal_instance *instance; |
| struct power_allocator_params *params = tz->governor_data; |
| |
| mutex_lock(&tz->lock); |
| list_for_each_entry(instance, &tz->thermal_instances, tz_node) { |
| if ((instance->trip != params->trip_max_desired_temperature) || |
| (!cdev_is_power_actor(instance->cdev))) |
| continue; |
| |
| instance->target = 0; |
| mutex_lock(&instance->cdev->lock); |
| instance->cdev->updated = false; |
| mutex_unlock(&instance->cdev->lock); |
| thermal_cdev_update(instance->cdev); |
| } |
| mutex_unlock(&tz->lock); |
| } |
| |
| /** |
| * power_allocator_bind() - bind the power_allocator governor to a thermal zone |
| * @tz: thermal zone to bind it to |
| * |
| * Initialize the PID controller parameters and bind it to the thermal |
| * zone. |
| * |
| * Return: 0 on success, or -ENOMEM if we ran out of memory. |
| */ |
| static int power_allocator_bind(struct thermal_zone_device *tz) |
| { |
| int ret; |
| struct power_allocator_params *params; |
| int control_temp; |
| |
| params = kzalloc(sizeof(*params), GFP_KERNEL); |
| if (!params) |
| return -ENOMEM; |
| |
| if (!tz->tzp) { |
| tz->tzp = kzalloc(sizeof(*tz->tzp), GFP_KERNEL); |
| if (!tz->tzp) { |
| ret = -ENOMEM; |
| goto free_params; |
| } |
| |
| params->allocated_tzp = true; |
| } |
| |
| if (!tz->tzp->sustainable_power) |
| dev_warn(&tz->device, "power_allocator: sustainable_power will be estimated\n"); |
| |
| get_governor_trips(tz, params); |
| |
| if (tz->trips > 0) { |
| ret = tz->ops->get_trip_temp(tz, |
| params->trip_max_desired_temperature, |
| &control_temp); |
| if (!ret) |
| estimate_pid_constants(tz, tz->tzp->sustainable_power, |
| params->trip_switch_on, |
| control_temp, false); |
| } |
| |
| reset_pid_controller(params); |
| |
| tz->governor_data = params; |
| |
| return 0; |
| |
| free_params: |
| kfree(params); |
| |
| return ret; |
| } |
| |
| static void power_allocator_unbind(struct thermal_zone_device *tz) |
| { |
| struct power_allocator_params *params = tz->governor_data; |
| |
| dev_dbg(&tz->device, "Unbinding from thermal zone %d\n", tz->id); |
| |
| if (params->allocated_tzp) { |
| kfree(tz->tzp); |
| tz->tzp = NULL; |
| } |
| |
| kfree(tz->governor_data); |
| tz->governor_data = NULL; |
| } |
| |
| static int power_allocator_throttle(struct thermal_zone_device *tz, int trip) |
| { |
| int ret; |
| int switch_on_temp, control_temp; |
| struct power_allocator_params *params = tz->governor_data; |
| |
| /* |
| * We get called for every trip point but we only need to do |
| * our calculations once |
| */ |
| if (trip != params->trip_max_desired_temperature) |
| return 0; |
| |
| ret = tz->ops->get_trip_temp(tz, params->trip_switch_on, |
| &switch_on_temp); |
| if (!ret && (tz->temperature < switch_on_temp)) { |
| tz->passive = 0; |
| reset_pid_controller(params); |
| allow_maximum_power(tz); |
| return 0; |
| } |
| |
| tz->passive = 1; |
| |
| ret = tz->ops->get_trip_temp(tz, params->trip_max_desired_temperature, |
| &control_temp); |
| if (ret) { |
| dev_warn(&tz->device, |
| "Failed to get the maximum desired temperature: %d\n", |
| ret); |
| return ret; |
| } |
| |
| return allocate_power(tz, control_temp); |
| } |
| |
| static struct thermal_governor thermal_gov_power_allocator = { |
| .name = "power_allocator", |
| .bind_to_tz = power_allocator_bind, |
| .unbind_from_tz = power_allocator_unbind, |
| .throttle = power_allocator_throttle, |
| }; |
| THERMAL_GOVERNOR_DECLARE(thermal_gov_power_allocator); |