// 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_actor - internal power information for power actor
* @req_power: requested power value (not weighted)
* @max_power: max allocatable power for this actor
* @granted_power: granted power for this actor
* @extra_actor_power: extra power that this actor can receive
* @weighted_req_power: weighted requested power as input to IPA
*/
struct power_actor {
u32 req_power;
u32 max_power;
u32 granted_power;
u32 extra_actor_power;
u32 weighted_req_power;
};
/**
* 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
* @update_cdevs: whether or not update cdevs on the next run
* @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: last passive trip point of the thermal zone. The
* temperature we are controlling for.
* @total_weight: Sum of all thermal instances weights
* @num_actors: number of cooling devices supporting IPA callbacks
* @buffer_size: internal buffer size, to avoid runtime re-calculation
* @power: buffer for all power actors internal power information
*/
struct power_allocator_params {
bool allocated_tzp;
bool update_cdevs;
s64 err_integral;
s32 prev_err;
u32 sustainable_power;
const struct thermal_trip *trip_switch_on;
const struct thermal_trip *trip_max;
int total_weight;
unsigned int num_actors;
unsigned int buffer_size;
struct power_actor *power;
};
static bool power_actor_is_valid(struct power_allocator_params *params,
struct thermal_instance *instance)
{
return (instance->trip == params->trip_max &&
cdev_is_power_actor(instance->cdev));
}
/**
* 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)
{
struct power_allocator_params *params = tz->governor_data;
struct thermal_cooling_device *cdev;
struct thermal_instance *instance;
u32 sustainable_power = 0;
u32 min_power;
list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
if (!power_actor_is_valid(params, instance))
continue;
cdev = instance->cdev;
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)
{
struct power_allocator_params *params = tz->governor_data;
s64 p, i, d, power_range;
s32 err, max_power_frac;
u32 sustainable_power;
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
* @power: buffer for all power actors internal power information
* @num_actors: number of power actors in this thermal zone
* @total_req_power: sum of all weighted requested power for all actors
* @power_range: total allocated power
*
* 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.
*/
static void divvy_up_power(struct power_actor *power, int num_actors,
u32 total_req_power, u32 power_range)
{
u32 capped_extra_power = 0;
u32 extra_power = 0;
int i;
/*
* Prevent division by 0 if none of the actors request power.
*/
if (!total_req_power)
total_req_power = 1;
for (i = 0; i < num_actors; i++) {
struct power_actor *pa = &power[i];
u64 req_range = (u64)pa->req_power * power_range;
pa->granted_power = DIV_ROUND_CLOSEST_ULL(req_range,
total_req_power);
if (pa->granted_power > pa->max_power) {
extra_power += pa->granted_power - pa->max_power;
pa->granted_power = pa->max_power;
}
pa->extra_actor_power = pa->max_power - pa->granted_power;
capped_extra_power += pa->extra_actor_power;
}
if (!extra_power || !capped_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);
for (i = 0; i < num_actors; i++) {
struct power_actor *pa = &power[i];
u64 extra_range = pa->extra_actor_power;
extra_range *= extra_power;
pa->granted_power += DIV_ROUND_CLOSEST_ULL(extra_range,
capped_extra_power);
}
}
static void allocate_power(struct thermal_zone_device *tz, int control_temp)
{
struct power_allocator_params *params = tz->governor_data;
unsigned int num_actors = params->num_actors;
struct power_actor *power = params->power;
struct thermal_cooling_device *cdev;
struct thermal_instance *instance;
u32 total_weighted_req_power = 0;
u32 max_allocatable_power = 0;
u32 total_granted_power = 0;
u32 total_req_power = 0;
u32 power_range, weight;
int i = 0, ret;
if (!num_actors)
return;
/* Clean all buffers for new power estimations */
memset(power, 0, params->buffer_size);
list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
struct power_actor *pa = &power[i];
if (!power_actor_is_valid(params, instance))
continue;
cdev = instance->cdev;
ret = cdev->ops->get_requested_power(cdev, &pa->req_power);
if (ret)
continue;
if (!params->total_weight)
weight = 1 << FRAC_BITS;
else
weight = instance->weight;
pa->weighted_req_power = frac_to_int(weight * pa->req_power);
ret = cdev->ops->state2power(cdev, instance->lower,
&pa->max_power);
if (ret)
continue;
total_req_power += pa->req_power;
max_allocatable_power += pa->max_power;
total_weighted_req_power += pa->weighted_req_power;
i++;
}
power_range = pid_controller(tz, control_temp, max_allocatable_power);
divvy_up_power(power, num_actors, total_weighted_req_power,
power_range);
i = 0;
list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
struct power_actor *pa = &power[i];
if (!power_actor_is_valid(params, instance))
continue;
power_actor_set_power(instance->cdev, instance,
pa->granted_power);
total_granted_power += pa->granted_power;
trace_thermal_power_actor(tz, i, pa->req_power,
pa->granted_power);
i++;
}
trace_thermal_power_allocator(tz, total_req_power, total_granted_power,
num_actors, power_range,
max_allocatable_power, tz->temperature,
control_temp - tz->temperature);
}
/**
* 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_desc *td;
for_each_trip_desc(tz, td) {
const struct thermal_trip *trip = &td->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 = last_passive;
} else if (first_passive) {
params->trip_switch_on = NULL;
params->trip_max = first_passive;
} else {
params->trip_switch_on = NULL;
params->trip_max = 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 power_allocator_params *params = tz->governor_data;
struct thermal_cooling_device *cdev;
struct thermal_instance *instance;
u32 req_power;
list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
if (!power_actor_is_valid(params, instance))
continue;
cdev = instance->cdev;
instance->target = 0;
mutex_lock(&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 (params->update_cdevs)
__thermal_cdev_update(cdev);
mutex_unlock(&cdev->lock);
}
}
/**
* check_power_actors() - Check all cooling devices and warn when they are
* not power actors
* @tz: thermal zone to operate on
* @params: power allocator private data
*
* 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.
*
* If all of the cooling devices currently attached to @tz implement the power
* actor API, return the number of them (which may be 0, because some cooling
* devices may be attached later). Otherwise, return -EINVAL.
*/
static int check_power_actors(struct thermal_zone_device *tz,
struct power_allocator_params *params)
{
struct thermal_instance *instance;
int ret = 0;
list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
if (instance->trip != params->trip_max)
continue;
if (!cdev_is_power_actor(instance->cdev)) {
dev_warn(&tz->device, "power_allocator: %s is not a power actor\n",
instance->cdev->type);
return -EINVAL;
}
ret++;
}
return ret;
}
static int allocate_actors_buffer(struct power_allocator_params *params,
int num_actors)
{
int ret;
kfree(params->power);
/* There might be no cooling devices yet. */
if (!num_actors) {
ret = 0;
goto clean_state;
}
params->power = kcalloc(num_actors, sizeof(struct power_actor),
GFP_KERNEL);
if (!params->power) {
ret = -ENOMEM;
goto clean_state;
}
params->num_actors = num_actors;
params->buffer_size = num_actors * sizeof(struct power_actor);
return 0;
clean_state:
params->num_actors = 0;
params->buffer_size = 0;
params->power = NULL;
return ret;
}
static void power_allocator_update_tz(struct thermal_zone_device *tz,
enum thermal_notify_event reason)
{
struct power_allocator_params *params = tz->governor_data;
struct thermal_instance *instance;
int num_actors = 0;
switch (reason) {
case THERMAL_TZ_BIND_CDEV:
case THERMAL_TZ_UNBIND_CDEV:
list_for_each_entry(instance, &tz->thermal_instances, tz_node)
if (power_actor_is_valid(params, instance))
num_actors++;
if (num_actors == params->num_actors)
return;
allocate_actors_buffer(params, num_actors);
break;
case THERMAL_INSTANCE_WEIGHT_CHANGED:
params->total_weight = 0;
list_for_each_entry(instance, &tz->thermal_instances, tz_node)
if (power_actor_is_valid(params, instance))
params->total_weight += instance->weight;
break;
default:
break;
}
}
/**
* 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)
{
struct power_allocator_params *params;
int ret;
params = kzalloc(sizeof(*params), GFP_KERNEL);
if (!params)
return -ENOMEM;
get_governor_trips(tz, params);
ret = check_power_actors(tz, params);
if (ret < 0) {
dev_warn(&tz->device, "power_allocator: binding failed\n");
kfree(params);
return ret;
}
ret = allocate_actors_buffer(params, ret);
if (ret) {
dev_warn(&tz->device, "power_allocator: allocation failed\n");
kfree(params);
return ret;
}
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");
else
params->sustainable_power = tz->tzp->sustainable_power;
if (params->trip_max)
estimate_pid_constants(tz, tz->tzp->sustainable_power,
params->trip_switch_on,
params->trip_max->temperature);
reset_pid_controller(params);
tz->governor_data = params;
return 0;
free_params:
kfree(params->power);
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(params->power);
kfree(tz->governor_data);
tz->governor_data = NULL;
}
static void power_allocator_manage(struct thermal_zone_device *tz)
{
struct power_allocator_params *params = tz->governor_data;
const struct thermal_trip *trip = params->trip_switch_on;
lockdep_assert_held(&tz->lock);
if (trip && tz->temperature < trip->temperature) {
reset_pid_controller(params);
allow_maximum_power(tz);
params->update_cdevs = false;
return;
}
if (!params->trip_max)
return;
allocate_power(tz, params->trip_max->temperature);
params->update_cdevs = true;
}
static struct thermal_governor thermal_gov_power_allocator = {
.name = "power_allocator",
.bind_to_tz = power_allocator_bind,
.unbind_from_tz = power_allocator_unbind,
.manage = power_allocator_manage,
.update_tz = power_allocator_update_tz,
};
THERMAL_GOVERNOR_DECLARE(thermal_gov_power_allocator);
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