linux/drivers/thermal/gov_power_allocator.c
Rafael J. Wysocki 8c35b1f472 thermal: core: Pass trip pointer to governor throttle callback
Modify the governor .throttle() callback definition so that it takes a
trip pointer instead of a trip index as its second argument, adjust the
governors accordingly and update the core code invoking .throttle().

This causes the governors to become independent of the representation
of the list of trips in the thermal zone structure.

This change is not expected to alter the general functionality.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Daniel Lezcano <daniel.lezcano@linaro.org>
2023-10-20 19:26:37 +02:00

715 lines
20 KiB
C

// 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/slab.h>
#include <linux/thermal.h>
#define CREATE_TRACE_POINTS
#include "thermal_trace_ipa.h"
#include "thermal_core.h"
#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.
* @sustainable_power: Sustainable power (heat) that this thermal zone can
* dissipate
* @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 NULL.
* @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;
u32 sustainable_power;
const struct thermal_trip *trip_switch_on;
const struct thermal_trip *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 (!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 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,
const struct thermal_trip *trip_switch_on,
int control_temp)
{
u32 temperature_threshold = control_temp;
s32 k_i;
if (trip_switch_on)
temperature_threshold -= trip_switch_on->temperature;
/*
* 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;
const struct thermal_trip *trip_max_desired_temperature =
params->trip_max_desired_temperature;
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;
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)
return -ENODEV;
/*
* 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)
return -ENOMEM;
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);
return ret;
}
/**
* get_governor_trips() - get 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)
{
const struct thermal_trip *first_passive = NULL;
const struct thermal_trip *last_passive = NULL;
const struct thermal_trip *last_active = NULL;
const struct thermal_trip *trip;
for_each_trip(tz, trip) {
switch (trip->type) {
case THERMAL_TRIP_PASSIVE:
if (!first_passive) {
first_passive = trip;
break;
}
last_passive = trip;
break;
case THERMAL_TRIP_ACTIVE:
last_active = trip;
break;
default:
break;
}
}
if (last_passive) {
params->trip_switch_on = first_passive;
params->trip_max_desired_temperature = last_passive;
} else if (first_passive) {
params->trip_switch_on = NULL;
params->trip_max_desired_temperature = first_passive;
} else {
params->trip_switch_on = NULL;
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;
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);
}
}
/**
* 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;
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 (params->trip_max_desired_temperature) {
int temp = params->trip_max_desired_temperature->temperature;
estimate_pid_constants(tz, tz->tzp->sustainable_power,
params->trip_switch_on, 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,
const struct thermal_trip *trip)
{
struct power_allocator_params *params = tz->governor_data;
bool update;
lockdep_assert_held(&tz->lock);
/*
* 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;
trip = params->trip_switch_on;
if (trip && tz->temperature < trip->temperature) {
update = tz->last_temperature >= trip->temperature;
tz->passive = 0;
reset_pid_controller(params);
allow_maximum_power(tz, update);
return 0;
}
tz->passive = 1;
return allocate_power(tz, params->trip_max_desired_temperature->temperature);
}
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);