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738 lines
21 KiB
738 lines
21 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* A power allocator to manage temperature |
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* |
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* Copyright (C) 2014 ARM Ltd. |
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* |
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*/ |
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|
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#define pr_fmt(fmt) "Power allocator: " fmt |
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#include <linux/rculist.h> |
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#include <linux/slab.h> |
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#include <linux/thermal.h> |
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|
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#define CREATE_TRACE_POINTS |
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#include <trace/events/thermal_power_allocator.h> |
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#include "thermal_core.h" |
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#define INVALID_TRIP -1 |
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#define FRAC_BITS 10 |
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#define int_to_frac(x) ((x) << FRAC_BITS) |
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#define frac_to_int(x) ((x) >> FRAC_BITS) |
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/** |
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* mul_frac() - multiply two fixed-point numbers |
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* @x: first multiplicand |
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* @y: second multiplicand |
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* |
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* Return: the result of multiplying two fixed-point numbers. The |
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* result is also a fixed-point number. |
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*/ |
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static inline s64 mul_frac(s64 x, s64 y) |
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{ |
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return (x * y) >> FRAC_BITS; |
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} |
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/** |
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* div_frac() - divide two fixed-point numbers |
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* @x: the dividend |
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* @y: the divisor |
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* |
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* Return: the result of dividing two fixed-point numbers. The |
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* result is also a fixed-point number. |
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*/ |
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static inline s64 div_frac(s64 x, s64 y) |
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{ |
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return div_s64(x << FRAC_BITS, y); |
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} |
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/** |
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* struct power_allocator_params - parameters for the power allocator governor |
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* @allocated_tzp: whether we have allocated tzp for this thermal zone and |
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* it needs to be freed on unbind |
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* @err_integral: accumulated error in the PID controller. |
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* @prev_err: error in the previous iteration of the PID controller. |
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* Used to calculate the derivative term. |
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* @trip_switch_on: first passive trip point of the thermal zone. The |
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* governor switches on when this trip point is crossed. |
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* If the thermal zone only has one passive trip point, |
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* @trip_switch_on should be INVALID_TRIP. |
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* @trip_max_desired_temperature: last passive trip point of the thermal |
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* zone. The temperature we are |
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* controlling for. |
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* @sustainable_power: Sustainable power (heat) that this thermal zone can |
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* dissipate |
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*/ |
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struct power_allocator_params { |
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bool allocated_tzp; |
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s64 err_integral; |
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s32 prev_err; |
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int trip_switch_on; |
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int trip_max_desired_temperature; |
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u32 sustainable_power; |
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}; |
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/** |
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* estimate_sustainable_power() - Estimate the sustainable power of a thermal zone |
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* @tz: thermal zone we are operating in |
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* |
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* For thermal zones that don't provide a sustainable_power in their |
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* thermal_zone_params, estimate one. Calculate it using the minimum |
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* power of all the cooling devices as that gives a valid value that |
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* can give some degree of functionality. For optimal performance of |
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* this governor, provide a sustainable_power in the thermal zone's |
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* thermal_zone_params. |
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*/ |
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static u32 estimate_sustainable_power(struct thermal_zone_device *tz) |
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{ |
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u32 sustainable_power = 0; |
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struct thermal_instance *instance; |
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struct power_allocator_params *params = tz->governor_data; |
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list_for_each_entry(instance, &tz->thermal_instances, tz_node) { |
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struct thermal_cooling_device *cdev = instance->cdev; |
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u32 min_power; |
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if (instance->trip != params->trip_max_desired_temperature) |
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continue; |
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if (!cdev_is_power_actor(cdev)) |
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continue; |
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if (cdev->ops->state2power(cdev, instance->upper, &min_power)) |
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continue; |
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sustainable_power += min_power; |
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} |
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return sustainable_power; |
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} |
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/** |
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* estimate_pid_constants() - Estimate the constants for the PID controller |
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* @tz: thermal zone for which to estimate the constants |
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* @sustainable_power: sustainable power for the thermal zone |
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* @trip_switch_on: trip point number for the switch on temperature |
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* @control_temp: target temperature for the power allocator governor |
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* |
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* This function is used to update the estimation of the PID |
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* controller constants in struct thermal_zone_parameters. |
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*/ |
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static void estimate_pid_constants(struct thermal_zone_device *tz, |
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u32 sustainable_power, int trip_switch_on, |
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int control_temp) |
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{ |
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int ret; |
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int switch_on_temp; |
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u32 temperature_threshold; |
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s32 k_i; |
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ret = tz->ops->get_trip_temp(tz, trip_switch_on, &switch_on_temp); |
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if (ret) |
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switch_on_temp = 0; |
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temperature_threshold = control_temp - switch_on_temp; |
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/* |
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* estimate_pid_constants() tries to find appropriate default |
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* values for thermal zones that don't provide them. If a |
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* system integrator has configured a thermal zone with two |
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* passive trip points at the same temperature, that person |
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* hasn't put any effort to set up the thermal zone properly |
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* so just give up. |
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*/ |
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if (!temperature_threshold) |
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return; |
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tz->tzp->k_po = int_to_frac(sustainable_power) / |
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temperature_threshold; |
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tz->tzp->k_pu = int_to_frac(2 * sustainable_power) / |
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temperature_threshold; |
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k_i = tz->tzp->k_pu / 10; |
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tz->tzp->k_i = k_i > 0 ? k_i : 1; |
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/* |
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* The default for k_d and integral_cutoff is 0, so we can |
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* leave them as they are. |
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*/ |
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} |
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/** |
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* get_sustainable_power() - Get the right sustainable power |
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* @tz: thermal zone for which to estimate the constants |
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* @params: parameters for the power allocator governor |
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* @control_temp: target temperature for the power allocator governor |
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* |
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* This function is used for getting the proper sustainable power value based |
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* on variables which might be updated by the user sysfs interface. If that |
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* happen the new value is going to be estimated and updated. It is also used |
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* after thermal zone binding, where the initial values where set to 0. |
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*/ |
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static u32 get_sustainable_power(struct thermal_zone_device *tz, |
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struct power_allocator_params *params, |
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int control_temp) |
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{ |
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u32 sustainable_power; |
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if (!tz->tzp->sustainable_power) |
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sustainable_power = estimate_sustainable_power(tz); |
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else |
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sustainable_power = tz->tzp->sustainable_power; |
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/* Check if it's init value 0 or there was update via sysfs */ |
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if (sustainable_power != params->sustainable_power) { |
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estimate_pid_constants(tz, sustainable_power, |
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params->trip_switch_on, control_temp); |
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/* Do the estimation only once and make available in sysfs */ |
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tz->tzp->sustainable_power = sustainable_power; |
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params->sustainable_power = sustainable_power; |
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} |
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return sustainable_power; |
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} |
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/** |
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* pid_controller() - PID controller |
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* @tz: thermal zone we are operating in |
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* @control_temp: the target temperature in millicelsius |
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* @max_allocatable_power: maximum allocatable power for this thermal zone |
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* |
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* This PID controller increases the available power budget so that the |
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* temperature of the thermal zone gets as close as possible to |
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* @control_temp and limits the power if it exceeds it. k_po is the |
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* proportional term when we are overshooting, k_pu is the |
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* proportional term when we are undershooting. integral_cutoff is a |
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* threshold below which we stop accumulating the error. The |
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* accumulated error is only valid if the requested power will make |
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* the system warmer. If the system is mostly idle, there's no point |
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* in accumulating positive error. |
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* |
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* Return: The power budget for the next period. |
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*/ |
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static u32 pid_controller(struct thermal_zone_device *tz, |
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int control_temp, |
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u32 max_allocatable_power) |
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{ |
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s64 p, i, d, power_range; |
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s32 err, max_power_frac; |
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u32 sustainable_power; |
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struct power_allocator_params *params = tz->governor_data; |
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max_power_frac = int_to_frac(max_allocatable_power); |
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sustainable_power = get_sustainable_power(tz, params, control_temp); |
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err = control_temp - tz->temperature; |
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err = int_to_frac(err); |
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/* Calculate the proportional term */ |
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p = mul_frac(err < 0 ? tz->tzp->k_po : tz->tzp->k_pu, err); |
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/* |
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* Calculate the integral term |
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* |
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* if the error is less than cut off allow integration (but |
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* the integral is limited to max power) |
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*/ |
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i = mul_frac(tz->tzp->k_i, params->err_integral); |
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if (err < int_to_frac(tz->tzp->integral_cutoff)) { |
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s64 i_next = i + mul_frac(tz->tzp->k_i, err); |
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if (abs(i_next) < max_power_frac) { |
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i = i_next; |
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params->err_integral += err; |
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} |
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} |
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/* |
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* Calculate the derivative term |
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* |
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* We do err - prev_err, so with a positive k_d, a decreasing |
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* error (i.e. driving closer to the line) results in less |
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* power being applied, slowing down the controller) |
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*/ |
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d = mul_frac(tz->tzp->k_d, err - params->prev_err); |
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d = div_frac(d, jiffies_to_msecs(tz->passive_delay_jiffies)); |
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params->prev_err = err; |
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power_range = p + i + d; |
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/* feed-forward the known sustainable dissipatable power */ |
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power_range = sustainable_power + frac_to_int(power_range); |
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power_range = clamp(power_range, (s64)0, (s64)max_allocatable_power); |
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trace_thermal_power_allocator_pid(tz, frac_to_int(err), |
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frac_to_int(params->err_integral), |
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frac_to_int(p), frac_to_int(i), |
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frac_to_int(d), power_range); |
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return power_range; |
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} |
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/** |
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* power_actor_set_power() - limit the maximum power a cooling device consumes |
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* @cdev: pointer to &thermal_cooling_device |
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* @instance: thermal instance to update |
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* @power: the power in milliwatts |
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* |
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* Set the cooling device to consume at most @power milliwatts. The limit is |
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* expected to be a cap at the maximum power consumption. |
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* |
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* Return: 0 on success, -EINVAL if the cooling device does not |
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* implement the power actor API or -E* for other failures. |
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*/ |
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static int |
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power_actor_set_power(struct thermal_cooling_device *cdev, |
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struct thermal_instance *instance, u32 power) |
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{ |
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unsigned long state; |
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int ret; |
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ret = cdev->ops->power2state(cdev, power, &state); |
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if (ret) |
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return ret; |
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instance->target = clamp_val(state, instance->lower, instance->upper); |
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mutex_lock(&cdev->lock); |
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cdev->updated = false; |
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mutex_unlock(&cdev->lock); |
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thermal_cdev_update(cdev); |
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return 0; |
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} |
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/** |
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* divvy_up_power() - divvy the allocated power between the actors |
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* @req_power: each actor's requested power |
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* @max_power: each actor's maximum available power |
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* @num_actors: size of the @req_power, @max_power and @granted_power's array |
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* @total_req_power: sum of @req_power |
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* @power_range: total allocated power |
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* @granted_power: output array: each actor's granted power |
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* @extra_actor_power: an appropriately sized array to be used in the |
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* function as temporary storage of the extra power given |
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* to the actors |
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* |
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* This function divides the total allocated power (@power_range) |
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* fairly between the actors. It first tries to give each actor a |
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* share of the @power_range according to how much power it requested |
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* compared to the rest of the actors. For example, if only one actor |
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* requests power, then it receives all the @power_range. If |
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* three actors each requests 1mW, each receives a third of the |
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* @power_range. |
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* |
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* If any actor received more than their maximum power, then that |
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* surplus is re-divvied among the actors based on how far they are |
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* from their respective maximums. |
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* |
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* Granted power for each actor is written to @granted_power, which |
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* should've been allocated by the calling function. |
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*/ |
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static void divvy_up_power(u32 *req_power, u32 *max_power, int num_actors, |
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u32 total_req_power, u32 power_range, |
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u32 *granted_power, u32 *extra_actor_power) |
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{ |
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u32 extra_power, capped_extra_power; |
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int i; |
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|
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/* |
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* Prevent division by 0 if none of the actors request power. |
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*/ |
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if (!total_req_power) |
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total_req_power = 1; |
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capped_extra_power = 0; |
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extra_power = 0; |
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for (i = 0; i < num_actors; i++) { |
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u64 req_range = (u64)req_power[i] * power_range; |
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granted_power[i] = DIV_ROUND_CLOSEST_ULL(req_range, |
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total_req_power); |
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if (granted_power[i] > max_power[i]) { |
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extra_power += granted_power[i] - max_power[i]; |
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granted_power[i] = max_power[i]; |
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} |
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extra_actor_power[i] = max_power[i] - granted_power[i]; |
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capped_extra_power += extra_actor_power[i]; |
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} |
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if (!extra_power) |
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return; |
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|
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/* |
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* Re-divvy the reclaimed extra among actors based on |
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* how far they are from the max |
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*/ |
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extra_power = min(extra_power, capped_extra_power); |
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if (capped_extra_power > 0) |
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for (i = 0; i < num_actors; i++) |
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granted_power[i] += (extra_actor_power[i] * |
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extra_power) / capped_extra_power; |
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} |
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static int allocate_power(struct thermal_zone_device *tz, |
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int control_temp) |
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{ |
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struct thermal_instance *instance; |
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struct power_allocator_params *params = tz->governor_data; |
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u32 *req_power, *max_power, *granted_power, *extra_actor_power; |
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u32 *weighted_req_power; |
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u32 total_req_power, max_allocatable_power, total_weighted_req_power; |
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u32 total_granted_power, power_range; |
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int i, num_actors, total_weight, ret = 0; |
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int trip_max_desired_temperature = params->trip_max_desired_temperature; |
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mutex_lock(&tz->lock); |
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num_actors = 0; |
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total_weight = 0; |
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list_for_each_entry(instance, &tz->thermal_instances, tz_node) { |
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if ((instance->trip == trip_max_desired_temperature) && |
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cdev_is_power_actor(instance->cdev)) { |
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num_actors++; |
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total_weight += instance->weight; |
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} |
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} |
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|
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if (!num_actors) { |
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ret = -ENODEV; |
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goto unlock; |
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} |
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/* |
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* We need to allocate five arrays of the same size: |
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* req_power, max_power, granted_power, extra_actor_power and |
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* weighted_req_power. They are going to be needed until this |
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* function returns. Allocate them all in one go to simplify |
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* the allocation and deallocation logic. |
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*/ |
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BUILD_BUG_ON(sizeof(*req_power) != sizeof(*max_power)); |
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BUILD_BUG_ON(sizeof(*req_power) != sizeof(*granted_power)); |
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BUILD_BUG_ON(sizeof(*req_power) != sizeof(*extra_actor_power)); |
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BUILD_BUG_ON(sizeof(*req_power) != sizeof(*weighted_req_power)); |
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req_power = kcalloc(num_actors * 5, sizeof(*req_power), GFP_KERNEL); |
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if (!req_power) { |
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ret = -ENOMEM; |
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goto unlock; |
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} |
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max_power = &req_power[num_actors]; |
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granted_power = &req_power[2 * num_actors]; |
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extra_actor_power = &req_power[3 * num_actors]; |
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weighted_req_power = &req_power[4 * num_actors]; |
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i = 0; |
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total_weighted_req_power = 0; |
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total_req_power = 0; |
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max_allocatable_power = 0; |
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list_for_each_entry(instance, &tz->thermal_instances, tz_node) { |
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int weight; |
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struct thermal_cooling_device *cdev = instance->cdev; |
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|
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if (instance->trip != trip_max_desired_temperature) |
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continue; |
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|
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if (!cdev_is_power_actor(cdev)) |
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continue; |
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|
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if (cdev->ops->get_requested_power(cdev, &req_power[i])) |
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continue; |
|
|
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if (!total_weight) |
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weight = 1 << FRAC_BITS; |
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else |
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weight = instance->weight; |
|
|
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weighted_req_power[i] = frac_to_int(weight * req_power[i]); |
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|
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if (cdev->ops->state2power(cdev, instance->lower, |
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&max_power[i])) |
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continue; |
|
|
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total_req_power += req_power[i]; |
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max_allocatable_power += max_power[i]; |
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total_weighted_req_power += weighted_req_power[i]; |
|
|
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i++; |
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} |
|
|
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power_range = pid_controller(tz, control_temp, max_allocatable_power); |
|
|
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divvy_up_power(weighted_req_power, max_power, num_actors, |
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total_weighted_req_power, power_range, granted_power, |
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extra_actor_power); |
|
|
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total_granted_power = 0; |
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i = 0; |
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list_for_each_entry(instance, &tz->thermal_instances, tz_node) { |
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if (instance->trip != trip_max_desired_temperature) |
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continue; |
|
|
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if (!cdev_is_power_actor(instance->cdev)) |
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continue; |
|
|
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power_actor_set_power(instance->cdev, instance, |
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granted_power[i]); |
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total_granted_power += granted_power[i]; |
|
|
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i++; |
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} |
|
|
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trace_thermal_power_allocator(tz, req_power, total_req_power, |
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granted_power, total_granted_power, |
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num_actors, power_range, |
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max_allocatable_power, tz->temperature, |
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control_temp - tz->temperature); |
|
|
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kfree(req_power); |
|
unlock: |
|
mutex_unlock(&tz->lock); |
|
|
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return ret; |
|
} |
|
|
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/** |
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* 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 |
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* |
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* The power allocator governor works optimally with two trips points: |
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* a "switch on" trip point and a "maximum desired temperature". These |
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* are defined as the first and last passive trip points. |
|
* |
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* If there is only one trip point, then that's considered to be the |
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* "maximum desired temperature" trip point and the governor is always |
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* on. If there are no passive or active trip points, then the |
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* 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, |
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struct power_allocator_params *params) |
|
{ |
|
int i, last_active, last_passive; |
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bool found_first_passive; |
|
|
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found_first_passive = false; |
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last_active = INVALID_TRIP; |
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last_passive = INVALID_TRIP; |
|
|
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for (i = 0; i < tz->trips; i++) { |
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enum thermal_trip_type type; |
|
int ret; |
|
|
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ret = tz->ops->get_trip_type(tz, i, &type); |
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if (ret) { |
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dev_warn(&tz->device, |
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"Failed to get trip point %d type: %d\n", i, |
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ret); |
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continue; |
|
} |
|
|
|
if (type == THERMAL_TRIP_PASSIVE) { |
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if (!found_first_passive) { |
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params->trip_switch_on = i; |
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found_first_passive = true; |
|
} else { |
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last_passive = i; |
|
} |
|
} else if (type == THERMAL_TRIP_ACTIVE) { |
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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; |
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} |
|
} |
|
|
|
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); |
|
} |
|
|
|
/** |
|
* 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->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; |
|
|
|
/* |
|
* 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);
|
|
|