OSCL-LXR linux-6.0.1/​drivers/​thermal/​gov_power_allocator.c	Source navigation Diff markup Identifier search General search
	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  * A power allocator to manage temperature
  *
  * Copyright (C) 2014 ARM Ltd.
  *
  */
 
 #define pr_fmt(fmt) "Power allocator: " fmt
 
 #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)
 
 /**
  * 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.
  * @sustainable_power:  Sustainable power (heat) that this thermal zone can
  *          dissipate
  */
 struct power_allocator_params {
     bool allocated_tzp;
     s64 err_integral;
     s32 prev_err;
     int trip_switch_on;
     int trip_max_desired_temperature;
     u32 sustainable_power;
 };
 
 /**
  * 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 (!cdev_is_power_actor(cdev))
             continue;
 
         if (cdev->ops->state2power(cdev, instance->upper, &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
  *
  * This function is used to update the estimation of the PID
  * controller constants in struct thermal_zone_parameters.
  */
 static void estimate_pid_constants(struct thermal_zone_device *tz,
                    u32 sustainable_power, int trip_switch_on,
                    int control_temp)
 {
     int ret;
     int switch_on_temp;
     u32 temperature_threshold;
     s32 k_i;
 
     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;
 
     tz->tzp->k_po = int_to_frac(sustainable_power) /
         temperature_threshold;
 
     tz->tzp->k_pu = int_to_frac(2 * sustainable_power) /
         temperature_threshold;
 
     k_i = tz->tzp->k_pu / 10;
     tz->tzp->k_i = k_i > 0 ? k_i : 1;
 
     /*
      * The default for k_d and integral_cutoff is 0, so we can
      * leave them as they are.
      */
 }
 
 /**
  * get_sustainable_power() - Get the right sustainable power
  * @tz:     thermal zone for which to estimate the constants
  * @params: parameters for the power allocator governor
  * @control_temp:   target temperature for the power allocator governor
  *
  * This function is used for getting the proper sustainable power value based
  * on variables which might be updated by the user sysfs interface. If that
  * happen the new value is going to be estimated and updated. It is also used
  * after thermal zone binding, where the initial values where set to 0.
  */
 static u32 get_sustainable_power(struct thermal_zone_device *tz,
                  struct power_allocator_params *params,
                  int control_temp)
 {
     u32 sustainable_power;
 
     if (!tz->tzp->sustainable_power)
         sustainable_power = estimate_sustainable_power(tz);
     else
         sustainable_power = tz->tzp->sustainable_power;
 
     /* Check if it's init value 0 or there was update via sysfs */
     if (sustainable_power != params->sustainable_power) {
         estimate_pid_constants(tz, sustainable_power,
                        params->trip_switch_on, control_temp);
 
         /* Do the estimation only once and make available in sysfs */
         tz->tzp->sustainable_power = sustainable_power;
         params->sustainable_power = sustainable_power;
     }
 
     return sustainable_power;
 }
 
 /**
  * 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);
 
     sustainable_power = get_sustainable_power(tz, params, control_temp);
 
     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, jiffies_to_msecs(tz->passive_delay_jiffies));
     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;
 }
 
 /**
  * power_actor_set_power() - limit the maximum power a cooling device consumes
  * @cdev:   pointer to &thermal_cooling_device
  * @instance:   thermal instance to update
  * @power:  the power in milliwatts
  *
  * Set the cooling device to consume at most @power milliwatts. The limit is
  * expected to be a cap at the maximum power consumption.
  *
  * Return: 0 on success, -EINVAL if the cooling device does not
  * implement the power actor API or -E* for other failures.
  */
 static int
 power_actor_set_power(struct thermal_cooling_device *cdev,
               struct thermal_instance *instance, u32 power)
 {
     unsigned long state;
     int ret;
 
     ret = cdev->ops->power2state(cdev, power, &state);
     if (ret)
         return ret;
 
     instance->target = clamp_val(state, instance->lower, instance->upper);
     mutex_lock(&cdev->lock);
     __thermal_cdev_update(cdev);
     mutex_unlock(&cdev->lock);
 
     return 0;
 }
 
 /**
  * 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++) {
             u64 extra_range = (u64)extra_actor_power[i] * extra_power;
             granted_power[i] += DIV_ROUND_CLOSEST_ULL(extra_range,
                              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, &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 (cdev->ops->state2power(cdev, instance->lower,
                        &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);
 
     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->num_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, bool update)
 {
     struct thermal_instance *instance;
     struct power_allocator_params *params = tz->governor_data;
     u32 req_power;
 
     mutex_lock(&tz->lock);
     list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
         struct thermal_cooling_device *cdev = instance->cdev;
 
         if ((instance->trip != params->trip_max_desired_temperature) ||
             (!cdev_is_power_actor(instance->cdev)))
             continue;
 
         instance->target = 0;
         mutex_lock(&instance->cdev->lock);
         /*
          * Call for updating the cooling devices local stats and avoid
          * periods of dozen of seconds when those have not been
          * maintained.
          */
         cdev->ops->get_requested_power(cdev, &req_power);
 
         if (update)
             __thermal_cdev_update(instance->cdev);
 
         mutex_unlock(&instance->cdev->lock);
     }
     mutex_unlock(&tz->lock);
 }
 
 /**
  * check_power_actors() - Check all cooling devices and warn when they are
  *          not power actors
  * @tz:     thermal zone to operate on
  *
  * Check all cooling devices in the @tz and warn every time they are missing
  * power actor API. The warning should help to investigate the issue, which
  * could be e.g. lack of Energy Model for a given device.
  *
  * Return: 0 on success, -EINVAL if any cooling device does not implement
  * the power actor API.
  */
 static int check_power_actors(struct thermal_zone_device *tz)
 {
     struct thermal_instance *instance;
     int ret = 0;
 
     list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
         if (!cdev_is_power_actor(instance->cdev)) {
             dev_warn(&tz->device, "power_allocator: %s is not a power actor\n",
                  instance->cdev->type);
             ret = -EINVAL;
         }
     }
 
     return ret;
 }
 
 /**
  * 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, or -EINVAL
  * when there are unsupported cooling devices in the @tz.
  */
 static int power_allocator_bind(struct thermal_zone_device *tz)
 {
     int ret;
     struct power_allocator_params *params;
     int control_temp;
 
     ret = check_power_actors(tz);
     if (ret)
         return ret;
 
     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->num_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);
     }
 
     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;
     bool update;
 
     /*
      * 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)) {
         update = (tz->last_temperature >= switch_on_temp);
         tz->passive = 0;
         reset_pid_controller(params);
         allow_maximum_power(tz, update);
         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);

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