On Wed, Jan 28, 2015 at 05:00:35PM +0000, Javi Merino wrote: > The power allocator governor is a thermal governor that controls system > and device power allocation to control temperature. Conceptually, the > implementation divides the sustainable power of a thermal zone among > all the heat sources in that zone. > > This governor relies on "power actors", entities that represent heat > sources. They can report current and maximum power consumption and > can set a given maximum power consumption, usually via a cooling > device. > > The governor uses a Proportional Integral Derivative (PID) controller > driven by the temperature of the thermal zone. The output of the > controller is a power budget that is then allocated to each power > actor that can have bearing on the temperature we are trying to > control. It decides how much power to give each cooling device based > on the performance they are requesting. The PID controller ensures > that the total power budget does not exceed the control temperature. > > Cc: Zhang Rui <[email protected]> > Cc: Eduardo Valentin <[email protected]> > Signed-off-by: Punit Agrawal <[email protected]> > Signed-off-by: Javi Merino <[email protected]> > --- > Documentation/thermal/power_allocator.txt | 241 +++++++++++++++ > drivers/thermal/Kconfig | 15 + > drivers/thermal/Makefile | 1 + > drivers/thermal/power_allocator.c | 478 > ++++++++++++++++++++++++++++++ > drivers/thermal/thermal_core.c | 9 +- > drivers/thermal/thermal_core.h | 8 + > include/linux/thermal.h | 37 ++- > 7 files changed, 782 insertions(+), 7 deletions(-) > create mode 100644 Documentation/thermal/power_allocator.txt > create mode 100644 drivers/thermal/power_allocator.c > > diff --git a/Documentation/thermal/power_allocator.txt > b/Documentation/thermal/power_allocator.txt > new file mode 100644 > index 000000000000..c9604e76c544 > --- /dev/null > +++ b/Documentation/thermal/power_allocator.txt > @@ -0,0 +1,241 @@ > +Power allocator governor tunables > +================================= > + > +Trip points > +----------- > + > +The governor requires the following two passive trip points: > + > +1. "switch on" trip point: temperature above which the governor > + control loop starts operating. > +2. "desired temperature" trip point: it should be higher than the > + "switch on" trip point. This the target temperature the governor > + is controlling for. > + > +PID Controller > +-------------- > + > +The power allocator governor implements a > +Proportional-Integral-Derivative controller (PID controller) with > +temperature as the control input and power as the controlled output: > + > + P_max = k_p * e + k_i * err_integral + k_d * diff_err + sustainable_power > + > +where > + e = desired_temperature - current_temperature > + err_integral is the sum of previous errors > + diff_err = e - previous_error > + > +It is similar to the one depicted below: > + > + k_d > + | > +current_temp | > + | v > + | +----------+ +---+ > + | +----->| diff_err |-->| X |------+ > + | | +----------+ +---+ | > + | | | tdp actor > + | | k_i | | > get_requested_power() > + | | | | | | | > + | | | | | | | ... > + v | v v v v v > + +---+ | +-------+ +---+ +---+ +---+ +----------+ > + | S |-------+----->| sum e |----->| X |--->| S |-->| S |-->|power | > + +---+ | +-------+ +---+ +---+ +---+ |allocation| > + ^ | ^ +----------+ > + | | | | | > + | | +---+ | | | > + | +------->| X |-------------------+ v v > + | +---+ granted > performance > +desired_temperature ^ > + | > + | > + k_po/k_pu > + > +Sustainable power > +----------------- > + > +An estimate of the sustainable dissipatable power (in mW) should be > +provided while registering the thermal zone. This estimates the > +sustained power that can be dissipated at the desired control > +temperature. This is the maximum sustained power for allocation at > +the desired maximum temperature. The actual sustained power can vary > +for a number of reasons. The closed loop controller will take care of > +variations such as environmental conditions, and some factors related > +to the speed-grade of the silicon. `sustainable_power` is therefore > +simply an estimate, and may be tuned to affect the aggressiveness of > +the thermal ramp. For reference, the sustainable power of a 4" phone > +is typically 2000mW, while on a 10" tablet is around 4500mW (may vary > +depending on screen size). > + > +If you are using device tree, do add it as a property of the > +thermal-zone. For example: > + > + thermal-zones { > + soc_thermal { > + polling-delay = <1000>; > + polling-delay-passive = <100>; > + sustainable-power = <2500>; > + ... > + > +Instead, if the thermal zone is registered from the platform code, pass a > +`thermal_zone_params` that has a `sustainable_power`. If no > +`thermal_zone_params` were being passed, then something like below > +will suffice: > + > + static const struct thermal_zone_params tz_params = { > + .sustainable_power = 3500, > + }; > + > +and then pass `tz_params` as the 5th parameter to > +`thermal_zone_device_register()` > + > +k_po and k_pu > +------------- > + > +The implementation of the PID controller in the power allocator > +thermal governor allows the configuration of two proportional term > +constants: `k_po` and `k_pu`. `k_po` is the proportional term > +constant during temperature overshoot periods (current temperature is > +above "desired temperature" trip point). Conversely, `k_pu` is the > +proportional term constant during temperature undershoot periods > +(current temperature below "desired temperature" trip point). > + > +These controls are intended as the primary mechanism for configuring > +the permitted thermal "ramp" of the system. For instance, a lower > +`k_pu` value will provide a slower ramp, at the cost of capping > +available capacity at a low temperature. On the other hand, a high > +value of `k_pu` will result in the governor granting very high power > +whilst temperature is low, and may lead to temperature overshooting. > + > +The default value for `k_pu` is: > + > + 2 * sustainable_power / (desired_temperature - switch_on_temp) > + > +This means that at `switch_on_temp` the output of the controller's > +proportional term will be 2 * `sustainable_power`. The default value > +for `k_po` is: > + > + sustainable_power / (desired_temperature - switch_on_temp) > + > +Focusing on the proportional and feed forward values of the PID > +controller equation we have: > + > + P_max = k_p * e + sustainable_power > + > +The proportional term is proportional to the difference between the > +desired temperature and the current one. When the current temperature > +is the desired one, then the proportional component is zero and > +`P_max` = `sustainable_power`. That is, the system should operate in > +thermal equilibrium under constant load. `sustainable_power` is only > +an estimate, which is the reason for closed-loop control such as this. > + > +Expanding `k_pu` we get: > + P_max = 2 * sustainable_power * (T_set - T) / (T_set - T_on) + > + sustainable_power > + > +where > + T_set is the desired temperature > + T is the current temperature > + T_on is the switch on temperature > + > +When the current temperature is the switch_on temperature, the above > +formula becomes: > + > + P_max = 2 * sustainable_power * (T_set - T_on) / (T_set - T_on) + > + sustainable_power = 2 * sustainable_power + sustainable_power = > + 3 * sustainable_power > + > +Therefore, the proportional term alone linearly decreases power from > +3 * `sustainable_power` to `sustainable_power` as the temperature > +rises from the switch on temperature to the desired temperature. > + > +k_i and integral_cutoff > +----------------------- > + > +`k_i` configures the PID loop's integral term constant. This term > +allows the PID controller to compensate for long term drift and for > +the quantized nature of the output control: cooling devices can't set > +the exact power that the governor requests. When the temperature > +error is below `integral_cutoff`, errors are accumulated in the > +integral term. This term is then multiplied by `k_i` and the result > +added to the output of the controller. Typically `k_i` is set low (1 > +or 2) and `integral_cutoff` is 0. > + > +k_d > +--- > + > +`k_d` configures the PID loop's derivative term constant. It's > +recommended to leave it as the default: 0. > + > +Cooling device power API > +======================== > + > +Cooling devices controlled by this governor must supply the additional > +"power" API in their `cooling_device_ops`. It consists on three ops: > + > +1. int get_requested_power(struct thermal_cooling_device *cdev, > + struct thermal_zone_device *tz, u32 *power); > +@cdev: The `struct thermal_cooling_device` pointer > +@tz: thermal zone in which we are currently operating > +@power: pointer in which to store the calculated power > + > +`get_requested_power()` calculates the power requested by the device > +in milliwatts and stores it in @power . It should return 0 on > +success, -E* on failure. This is currently used by the power > +allocator governor to calculate how much power to give to each cooling > +device. > + > +2. int state2power(struct thermal_cooling_device *cdev, struct > + thermal_zone_device *tz, unsigned long state, u32 *power); > +@cdev: The `struct thermal_cooling_device` pointer > +@tz: thermal zone in which we are currently operating > +@state: A cooling device state > +@power: pointer in which to store the equivalent power > + > +Convert cooling device state @state into power consumption in > +milliwatts and store it in @power. It should return 0 on success, -E* > +on failure. This is currently used by thermal core to calculate the > +maximum power that an actor can consume. > + > +3. int power2state(struct thermal_cooling_device *cdev, u32 power, > + unsigned long *state); > +@cdev: The `struct thermal_cooling_device` pointer > +@power: power in milliwatts > +@state: pointer in which to store the resulting state > + > +Calculate a cooling device state that would make the device consume at > +most @power mW and store it in @state. It should return 0 on success, > +-E* on failure. This is currently used by the thermal core to convert > +a given power set by the power allocator governor to a state that the > +cooling device can set. It is a function because this conversion may > +depend on external factors that may change so this function should the > +best conversion given "current circumstances". > + > +Cooling device weights > +---------------------- > + > +Weights are a mechanism to bias the allocation among cooling > +devices. They express the relative power efficiency of different > +cooling devices. Higher weight can be used to express higher power > +efficiency. Weighting is relative such that if each cooling device > +has a weight of one they are considered equal. This is particularly > +useful in heterogeneous systems where two cooling devices may perform > +the same kind of compute, but with different efficiency. For example, > +a system with two different types of processors. > + > +Weights are passed as part of the thermal zone's > +`thermal_bind_parameters`. > + > +Limitations of the power allocator governor > +=========================================== > + > +The power allocator governor's PID controller works best if there is a > +periodic tick. If you have a driver that calls > +`thermal_zone_device_update()` (or anything that ends up calling the > +governor's `throttle()` function) repetitively, the governor response > +won't be very good. Note that this is not particular to this > +governor, step-wise will also misbehave if you call its throttle() > +faster than the normal thermal framework tick (due to interrupts for > +example) as it will overreact. > diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig > index af40db0df58e..98a46383b19f 100644 > --- a/drivers/thermal/Kconfig > +++ b/drivers/thermal/Kconfig > @@ -71,6 +71,14 @@ config THERMAL_DEFAULT_GOV_USER_SPACE > Select this if you want to let the user space manage the > platform thermals. > > +config THERMAL_DEFAULT_GOV_POWER_ALLOCATOR > + bool "power_allocator" > + select THERMAL_GOV_POWER_ALLOCATOR > + help > + Select this if you want to control temperature based on > + system and device power allocation. This governor can only > + operate on cooling devices that implement the power API. > + > endchoice > > config THERMAL_GOV_FAIR_SHARE > @@ -99,6 +107,13 @@ config THERMAL_GOV_USER_SPACE > help > Enable this to let the user space manage the platform thermals. > > +config THERMAL_GOV_POWER_ALLOCATOR > + bool "Power allocator thermal governor" > + select THERMAL_POWER_ACTOR > + help > + Enable this to manage platform thermals by dynamically > + allocating and limiting power to devices. > + > config CPU_THERMAL > bool "generic cpu cooling support" > depends on CPU_FREQ > diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile > index fa0dc486790f..cd769ab06cbb 100644 > --- a/drivers/thermal/Makefile > +++ b/drivers/thermal/Makefile > @@ -14,6 +14,7 @@ thermal_sys-$(CONFIG_THERMAL_GOV_FAIR_SHARE) += > fair_share.o > thermal_sys-$(CONFIG_THERMAL_GOV_BANG_BANG) += gov_bang_bang.o > thermal_sys-$(CONFIG_THERMAL_GOV_STEP_WISE) += step_wise.o > thermal_sys-$(CONFIG_THERMAL_GOV_USER_SPACE) += user_space.o > +thermal_sys-$(CONFIG_THERMAL_GOV_POWER_ALLOCATOR) += power_allocator.o > > # cpufreq cooling > thermal_sys-$(CONFIG_CPU_THERMAL) += cpu_cooling.o > diff --git a/drivers/thermal/power_allocator.c > b/drivers/thermal/power_allocator.c > new file mode 100644 > index 000000000000..c929143aee67 > --- /dev/null > +++ b/drivers/thermal/power_allocator.c > @@ -0,0 +1,478 @@ > +/* > + * A power allocator to manage temperature > + * > + * Copyright (C) 2014 ARM Ltd. > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License version 2 as > + * published by the Free Software Foundation. > + * > + * This program is distributed "as is" WITHOUT ANY WARRANTY of any > + * kind, whether express or implied; without even the implied warranty > + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the > + * GNU General Public License for more details. > + */ > + > +#define pr_fmt(fmt) "Power allocator: " fmt > + > +#include <linux/rculist.h> > +#include <linux/slab.h> > +#include <linux/thermal.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; > +} > + > +enum power_allocator_trip_levels { > + TRIP_SWITCH_ON = 0, /* Switch on PID controller */ > + TRIP_MAX_DESIRED_TEMPERATURE, /* Temperature we are controlling for */ > + > + THERMAL_TRIP_NUM, > +}; > + > +/** > + * struct power_allocator_params - parameters for the power allocator > governor > + * @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. > + */ > +struct power_allocator_params { > + s64 err_integral; > + s32 prev_err; > +}; > + > +/** > + * pid_controller() - PID controller > + * @tz: thermal zone we are operating in > + * @current_temp: the current temperature in millicelsius > + * @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, > + unsigned long current_temp, > + unsigned long control_temp, > + u32 max_allocatable_power) > +{ > + s64 p, i, d, power_range; > + s32 err, max_power_frac; > + struct power_allocator_params *params = tz->governor_data; > + > + max_power_frac = int_to_frac(max_allocatable_power); > + > + err = ((s32)control_temp - (s32)current_temp); > + 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 (abs64(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); > + params->prev_err = err; > + > + power_range = p + i + d; > + > + /* feed-forward the known sustainable dissipatable power */ > + power_range = tz->tzp->sustainable_power + frac_to_int(power_range); > + > + return clamp(power_range, (s64)0, (s64)max_allocatable_power); > +} > + > +/** > + * 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 > + * > + * 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_power, capped_extra_power, extra_actor_power[num_actors];
Just now I noticed this variable-size array. I know the number of actors
are constant, and in average it should be less than 10 in magnitude, but
I don't believe variable-sized arrays are a good practice in kernel.
Even though I don't see this one as a treat, can we avoid it?
Sparse error:
drivers/thermal/power_allocator.c:172:64: error: bad constant expression
> + 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 = req_power[i] * power_range;
> +
> + granted_power[i] = div_u64(req_range, total_req_power);
> +
> + if (granted_power[i] > max_power[i]) {
> + extra_power += granted_power[i] - max_power[i];
> + granted_power[i] = max_power[i];
> + }
> +
> + extra_actor_power[i] = max_power[i] - granted_power[i];
> + capped_extra_power += extra_actor_power[i];
> + }
> +
> + if (!extra_power)
> + return;
> +
> + /*
> + * Re-divvy the reclaimed extra among actors based on
> + * how far they are from the max
> + */
> + extra_power = min(extra_power, capped_extra_power);
> + if (capped_extra_power > 0)
> + for (i = 0; i < num_actors; i++)
> + granted_power[i] += (extra_actor_power[i] *
> + extra_power) / capped_extra_power;
> +}
> +
> +static int allocate_power(struct thermal_zone_device *tz,
> + unsigned long current_temp,
> + unsigned long control_temp)
> +{
> + struct thermal_instance *instance;
> + u32 *req_power, *max_power, *granted_power;
> + u32 total_req_power, max_allocatable_power;
> + u32 power_range;
> + int i, num_actors, ret = 0;
> +
> + mutex_lock(&tz->lock);
> +
> + num_actors = 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++;
> +
> + req_power = devm_kcalloc(&tz->device, num_actors, sizeof(*req_power),
> + GFP_KERNEL);
> + if (!req_power) {
> + ret = -ENOMEM;
> + goto unlock;
> + }
> +
> + max_power = devm_kcalloc(&tz->device, num_actors, sizeof(*max_power),
> + GFP_KERNEL);
> + if (!max_power) {
> + ret = -ENOMEM;
> + goto free_req_power;
> + }
> +
> + granted_power = devm_kcalloc(&tz->device, num_actors,
> + sizeof(*granted_power), GFP_KERNEL);
> + if (!granted_power) {
> + ret = -ENOMEM;
> + goto free_max_power;
> + }
> +
> + i = 0;
> + total_req_power = 0;
> + max_allocatable_power = 0;
> +
> + list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
> + struct thermal_cooling_device *cdev = instance->cdev;
> +
> + if (instance->trip != TRIP_MAX_DESIRED_TEMPERATURE)
> + continue;
> +
> + if (!cdev_is_power_actor(cdev))
> + continue;
> +
> + if (cdev->ops->get_requested_power(cdev, tz, &req_power[i]))
> + continue;
> +
> + req_power[i] = frac_to_int(instance->weight * req_power[i]);
> +
> + if (power_actor_get_max_power(cdev, tz, &max_power[i]))
> + continue;
> +
> + total_req_power += req_power[i];
> + max_allocatable_power += max_power[i];
> +
> + i++;
> + }
> +
> + power_range = pid_controller(tz, current_temp, control_temp,
> + max_allocatable_power);
> +
> + divvy_up_power(req_power, max_power, num_actors, total_req_power,
> + power_range, granted_power);
> +
> + 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]);
> +
> + i++;
> + }
> +
> + devm_kfree(&tz->device, granted_power);
> +free_max_power:
> + devm_kfree(&tz->device, max_power);
> +free_req_power:
> + devm_kfree(&tz->device, req_power);
> +unlock:
> + mutex_unlock(&tz->lock);
> +
> + return ret;
> +}
> +
> +static int check_trips(struct thermal_zone_device *tz)
> +{
> + int ret;
> + enum thermal_trip_type type;
> +
> + if (tz->trips < THERMAL_TRIP_NUM)
> + return -EINVAL;
> +
> + ret = tz->ops->get_trip_type(tz, TRIP_SWITCH_ON, &type);
> + if (ret)
> + return ret;
> +
> + if (type != THERMAL_TRIP_PASSIVE)
> + return -EINVAL;
> +
> + ret = tz->ops->get_trip_type(tz, TRIP_MAX_DESIRED_TEMPERATURE, &type);
> + if (ret)
> + return ret;
> +
> + if (type != THERMAL_TRIP_PASSIVE)
> + return -EINVAL;
> +
> + return ret;
> +}
> +
> +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;
> +
> + list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
> + if ((instance->trip != TRIP_MAX_DESIRED_TEMPERATURE) ||
> + (!cdev_is_power_actor(instance->cdev)))
> + continue;
> +
> + instance->target = 0;
> + instance->cdev->updated = false;
> + thermal_cdev_update(instance->cdev);
> + }
> +}
> +
> +/**
> + * power_allocator_bind() - bind the power_allocator governor to a thermal
> zone
> + * @tz: thermal zone to bind it to
> + *
> + * Check that the thermal zone is valid for this governor, that is, it
> + * has two thermal trips. If so, initialize the PID controller
> + * parameters and bind it to the thermal zone.
> + *
> + * Return: 0 on success, -EINVAL if the trips were invalid or -ENOMEM
> + * if we ran out of memory.
> + */
> +static int power_allocator_bind(struct thermal_zone_device *tz)
> +{
> + int ret;
> + struct power_allocator_params *params;
> + unsigned long switch_on_temp, control_temp;
> + u32 temperature_threshold;
> +
> + ret = check_trips(tz);
> + if (ret) {
> + dev_err(&tz->device,
> + "thermal zone %s has wrong trip setup for power
> allocator\n",
> + tz->type);
> + return ret;
> + }
> +
> + if (!tz->tzp || !tz->tzp->sustainable_power) {
> + dev_err(&tz->device,
> + "power_allocator: missing sustainable_power\n");
> + return -EINVAL;
> + }
> +
> + params = devm_kzalloc(&tz->device, sizeof(*params), GFP_KERNEL);
> + if (!params)
> + return -ENOMEM;
> +
> + ret = tz->ops->get_trip_temp(tz, TRIP_SWITCH_ON, &switch_on_temp);
> + if (ret)
> + goto free;
> +
> + ret = tz->ops->get_trip_temp(tz, TRIP_MAX_DESIRED_TEMPERATURE,
> + &control_temp);
> + if (ret)
> + goto free;
> +
> + temperature_threshold = control_temp - switch_on_temp;
> +
> + tz->tzp->k_po = tz->tzp->k_po ?:
> + int_to_frac(tz->tzp->sustainable_power) / temperature_threshold;
> + tz->tzp->k_pu = tz->tzp->k_pu ?:
> + int_to_frac(2 * tz->tzp->sustainable_power) /
> + temperature_threshold;
> + tz->tzp->k_i = tz->tzp->k_i ?: int_to_frac(10) / 1000;
> + /*
> + * The default for k_d and integral_cutoff is 0, so we can
> + * leave them as they are.
> + */
> +
> + reset_pid_controller(params);
> +
> + tz->governor_data = params;
> +
> + return 0;
> +
> +free:
> + devm_kfree(&tz->device, params);
> + return ret;
> +}
> +
> +static void power_allocator_unbind(struct thermal_zone_device *tz)
> +{
> + dev_dbg(&tz->device, "Unbinding from thermal zone %d\n", tz->id);
> + devm_kfree(&tz->device, tz->governor_data);
> + tz->governor_data = NULL;
> +}
> +
> +static int power_allocator_throttle(struct thermal_zone_device *tz, int trip)
> +{
> + int ret;
> + unsigned long switch_on_temp, control_temp, current_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 != TRIP_MAX_DESIRED_TEMPERATURE)
> + return 0;
> +
> + ret = thermal_zone_get_temp(tz, ¤t_temp);
> + if (ret) {
> + dev_warn(&tz->device, "Failed to get temperature: %d\n", ret);
> + return ret;
> + }
> +
> + ret = tz->ops->get_trip_temp(tz, TRIP_SWITCH_ON, &switch_on_temp);
> + if (ret) {
> + dev_warn(&tz->device,
> + "Failed to get switch on temperature: %d\n", ret);
> + return ret;
> + }
> +
> + if (current_temp < 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, 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, current_temp, 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,
> +};
> +
> +int thermal_gov_power_allocator_register(void)
> +{
> + return thermal_register_governor(&thermal_gov_power_allocator);
> +}
> +
> +void thermal_gov_power_allocator_unregister(void)
> +{
> + thermal_unregister_governor(&thermal_gov_power_allocator);
> +}
> diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
> index a01d4a72bd93..b77b5416929c 100644
> --- a/drivers/thermal/thermal_core.c
> +++ b/drivers/thermal/thermal_core.c
> @@ -1567,7 +1567,7 @@ static void remove_trip_attrs(struct
> thermal_zone_device *tz)
> struct thermal_zone_device *thermal_zone_device_register(const char *type,
> int trips, int mask, void *devdata,
> struct thermal_zone_device_ops *ops,
> - const struct thermal_zone_params *tzp,
> + struct thermal_zone_params *tzp,
> int passive_delay, int polling_delay)
> {
> struct thermal_zone_device *tz;
> @@ -1923,7 +1923,11 @@ static int __init thermal_register_governors(void)
> if (result)
> return result;
>
> - return thermal_gov_user_space_register();
> + result = thermal_gov_user_space_register();
> + if (result)
> + return result;
> +
> + return thermal_gov_power_allocator_register();
> }
>
> static void thermal_unregister_governors(void)
> @@ -1932,6 +1936,7 @@ static void thermal_unregister_governors(void)
> thermal_gov_fair_share_unregister();
> thermal_gov_bang_bang_unregister();
> thermal_gov_user_space_unregister();
> + thermal_gov_power_allocator_unregister();
> }
>
> static int __init thermal_init(void)
> diff --git a/drivers/thermal/thermal_core.h b/drivers/thermal/thermal_core.h
> index 0531c752fbbb..28aa326806eb 100644
> --- a/drivers/thermal/thermal_core.h
> +++ b/drivers/thermal/thermal_core.h
> @@ -85,6 +85,14 @@ static inline int thermal_gov_user_space_register(void) {
> return 0; }
> static inline void thermal_gov_user_space_unregister(void) {}
> #endif /* CONFIG_THERMAL_GOV_USER_SPACE */
>
> +#ifdef CONFIG_THERMAL_GOV_POWER_ALLOCATOR
> +int thermal_gov_power_allocator_register(void);
> +void thermal_gov_power_allocator_unregister(void);
> +#else
> +static inline int thermal_gov_power_allocator_register(void) { return 0; }
> +static inline void thermal_gov_power_allocator_unregister(void) {}
> +#endif /* CONFIG_THERMAL_GOV_POWER_ALLOCATOR */
> +
> /* device tree support */
> #ifdef CONFIG_THERMAL_OF
> int of_parse_thermal_zones(void);
> diff --git a/include/linux/thermal.h b/include/linux/thermal.h
> index 288ac6fd743d..b42f790bb23c 100644
> --- a/include/linux/thermal.h
> +++ b/include/linux/thermal.h
> @@ -56,6 +56,8 @@
> #define DEFAULT_THERMAL_GOVERNOR "fair_share"
> #elif defined(CONFIG_THERMAL_DEFAULT_GOV_USER_SPACE)
> #define DEFAULT_THERMAL_GOVERNOR "user_space"
> +#elif defined(CONFIG_THERMAL_DEFAULT_GOV_POWER_ALLOCATOR)
> +#define DEFAULT_THERMAL_GOVERNOR "power_allocator"
> #endif
>
> struct thermal_zone_device;
> @@ -151,8 +153,7 @@ struct thermal_attr {
> * @devdata: private pointer for device private data
> * @trips: number of trip points the thermal zone supports
> * @passive_delay: number of milliseconds to wait between polls when
> - * performing passive cooling. Currenty only used by the
> - * step-wise governor
> + * performing passive cooling.
> * @polling_delay: number of milliseconds to wait between polls when
> * checking whether trip points have been crossed (0 for
> * interrupt driven systems)
> @@ -162,7 +163,6 @@ struct thermal_attr {
> * @last_temperature: previous temperature read
> * @emul_temperature: emulated temperature when using
> CONFIG_THERMAL_EMULATION
> * @passive: 1 if you've crossed a passive trip point, 0 otherwise.
> - * Currenty only used by the step-wise governor.
> * @forced_passive: If > 0, temperature at which to switch on all ACPI
> * processor cooling devices. Currently only used by the
> * step-wise governor.
> @@ -194,7 +194,7 @@ struct thermal_zone_device {
> int passive;
> unsigned int forced_passive;
> struct thermal_zone_device_ops *ops;
> - const struct thermal_zone_params *tzp;
> + struct thermal_zone_params *tzp;
> struct thermal_governor *governor;
> void *governor_data;
> struct list_head thermal_instances;
> @@ -269,6 +269,33 @@ struct thermal_zone_params {
>
> int num_tbps; /* Number of tbp entries */
> struct thermal_bind_params *tbp;
> +
> + /*
> + * Sustainable power (heat) that this thermal zone can dissipate in
> + * mW
> + */
> + u32 sustainable_power;
> +
> + /*
> + * Proportional parameter of the PID controller when
> + * overshooting (i.e., when temperature is below the target)
> + */
> + s32 k_po;
> +
> + /*
> + * Proportional parameter of the PID controller when
> + * undershooting
> + */
> + s32 k_pu;
> +
> + /* Integral parameter of the PID controller */
> + s32 k_i;
> +
> + /* Derivative parameter of the PID controller */
> + s32 k_d;
> +
> + /* threshold below which the error is no longer accumulated */
> + s32 integral_cutoff;
> };
>
> struct thermal_genl_event {
> @@ -343,7 +370,7 @@ int power_actor_set_power(struct thermal_cooling_device *,
> struct thermal_instance *, u32);
> struct thermal_zone_device *thermal_zone_device_register(const char *, int,
> int,
> void *, struct thermal_zone_device_ops *,
> - const struct thermal_zone_params *, int, int);
> + struct thermal_zone_params *, int, int);
> void thermal_zone_device_unregister(struct thermal_zone_device *);
>
> int thermal_zone_bind_cooling_device(struct thermal_zone_device *, int,
> --
> 1.9.1
>
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