Linux-libre 4.2-gnu

1 files changed, 544 insertions, 0 deletions

diff --git a/drivers/thermal/power_allocator.c b/drivers/thermal/power_allocator.c
new file mode 100644
index 000000000..251676902
--- /dev/null
+++ b/drivers/thermal/power_allocator.c
@@ -0,0 +1,544 @@
+/*
+ * 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>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/thermal_power_allocator.h>
+
+#include "thermal_core.h"
+
+#define FRAC_BITS 10
+#define int_to_frac(x) ((x) << FRAC_BITS)
+#define frac_to_int(x) ((x) >> FRAC_BITS)
+
+/**
+ * mul_frac() - multiply two fixed-point numbers
+ * @x:	first multiplicand
+ * @y:	second multiplicand
+ *
+ * Return: the result of multiplying two fixed-point numbers.  The
+ * result is also a fixed-point number.
+ */
+static inline s64 mul_frac(s64 x, s64 y)
+{
+	return (x * y) >> FRAC_BITS;
+}
+
+/**
+ * div_frac() - divide two fixed-point numbers
+ * @x:	the dividend
+ * @y:	the divisor
+ *
+ * Return: the result of dividing two fixed-point numbers.  The
+ * result is also a fixed-point number.
+ */
+static inline s64 div_frac(s64 x, s64 y)
+{
+	return div_s64(x << FRAC_BITS, y);
+}
+
+/**
+ * struct power_allocator_params - parameters for the power allocator governor
+ * @err_integral:	accumulated error in the PID controller.
+ * @prev_err:	error in the previous iteration of the PID controller.
+ *		Used to calculate the derivative term.
+ * @trip_switch_on:	first passive trip point of the thermal zone.  The
+ *			governor switches on when this trip point is crossed.
+ * @trip_max_desired_temperature:	last passive trip point of the thermal
+ *					zone.  The temperature we are
+ *					controlling for.
+ */
+struct power_allocator_params {
+	s64 err_integral;
+	s32 prev_err;
+	int trip_switch_on;
+	int trip_max_desired_temperature;
+};
+
+/**
+ * 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);
+	d = div_frac(d, tz->passive_delay);
+	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);
+
+	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;
+}
+
+/**
+ * divvy_up_power() - divvy the allocated power between the actors
+ * @req_power:	each actor's requested power
+ * @max_power:	each actor's maximum available power
+ * @num_actors:	size of the @req_power, @max_power and @granted_power's array
+ * @total_req_power: sum of @req_power
+ * @power_range:	total allocated power
+ * @granted_power:	output array: each actor's granted power
+ * @extra_actor_power:	an appropriately sized array to be used in the
+ *			function as temporary storage of the extra power given
+ *			to the actors
+ *
+ * This function divides the total allocated power (@power_range)
+ * fairly between the actors.  It first tries to give each actor a
+ * share of the @power_range according to how much power it requested
+ * compared to the rest of the actors.  For example, if only one actor
+ * requests power, then it receives all the @power_range.  If
+ * three actors each requests 1mW, each receives a third of the
+ * @power_range.
+ *
+ * If any actor received more than their maximum power, then that
+ * surplus is re-divvied among the actors based on how far they are
+ * from their respective maximums.
+ *
+ * Granted power for each actor is written to @granted_power, which
+ * should've been allocated by the calling function.
+ */
+static void divvy_up_power(u32 *req_power, u32 *max_power, int num_actors,
+			   u32 total_req_power, u32 power_range,
+			   u32 *granted_power, u32 *extra_actor_power)
+{
+	u32 extra_power, capped_extra_power;
+	int i;
+
+	/*
+	 * Prevent division by 0 if none of the actors request power.
+	 */
+	if (!total_req_power)
+		total_req_power = 1;
+
+	capped_extra_power = 0;
+	extra_power = 0;
+	for (i = 0; i < num_actors; i++) {
+		u64 req_range = req_power[i] * power_range;
+
+		granted_power[i] = DIV_ROUND_CLOSEST_ULL(req_range,
+							 total_req_power);
+
+		if (granted_power[i] > max_power[i]) {
+			extra_power += granted_power[i] - max_power[i];
+			granted_power[i] = max_power[i];
+		}
+
+		extra_actor_power[i] = max_power[i] - granted_power[i];
+		capped_extra_power += extra_actor_power[i];
+	}
+
+	if (!extra_power)
+		return;
+
+	/*
+	 * Re-divvy the reclaimed extra among actors based on
+	 * how far they are from the max
+	 */
+	extra_power = min(extra_power, capped_extra_power);
+	if (capped_extra_power > 0)
+		for (i = 0; i < num_actors; i++)
+			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;
+	struct power_allocator_params *params = tz->governor_data;
+	u32 *req_power, *max_power, *granted_power, *extra_actor_power;
+	u32 *weighted_req_power;
+	u32 total_req_power, max_allocatable_power, total_weighted_req_power;
+	u32 total_granted_power, power_range;
+	int i, num_actors, total_weight, ret = 0;
+	int trip_max_desired_temperature = params->trip_max_desired_temperature;
+
+	mutex_lock(&tz->lock);
+
+	num_actors = 0;
+	total_weight = 0;
+	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
+		if ((instance->trip == trip_max_desired_temperature) &&
+		    cdev_is_power_actor(instance->cdev)) {
+			num_actors++;
+			total_weight += instance->weight;
+		}
+	}
+
+	/*
+	 * We need to allocate five arrays of the same size:
+	 * req_power, max_power, granted_power, extra_actor_power and
+	 * weighted_req_power.  They are going to be needed until this
+	 * function returns.  Allocate them all in one go to simplify
+	 * the allocation and deallocation logic.
+	 */
+	BUILD_BUG_ON(sizeof(*req_power) != sizeof(*max_power));
+	BUILD_BUG_ON(sizeof(*req_power) != sizeof(*granted_power));
+	BUILD_BUG_ON(sizeof(*req_power) != sizeof(*extra_actor_power));
+	BUILD_BUG_ON(sizeof(*req_power) != sizeof(*weighted_req_power));
+	req_power = kcalloc(num_actors * 5, sizeof(*req_power), GFP_KERNEL);
+	if (!req_power) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+
+	max_power = &req_power[num_actors];
+	granted_power = &req_power[2 * num_actors];
+	extra_actor_power = &req_power[3 * num_actors];
+	weighted_req_power = &req_power[4 * num_actors];
+
+	i = 0;
+	total_weighted_req_power = 0;
+	total_req_power = 0;
+	max_allocatable_power = 0;
+
+	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
+		int weight;
+		struct thermal_cooling_device *cdev = instance->cdev;
+
+		if (instance->trip != trip_max_desired_temperature)
+			continue;
+
+		if (!cdev_is_power_actor(cdev))
+			continue;
+
+		if (cdev->ops->get_requested_power(cdev, tz, &req_power[i]))
+			continue;
+
+		if (!total_weight)
+			weight = 1 << FRAC_BITS;
+		else
+			weight = instance->weight;
+
+		weighted_req_power[i] = frac_to_int(weight * req_power[i]);
+
+		if (power_actor_get_max_power(cdev, tz, &max_power[i]))
+			continue;
+
+		total_req_power += req_power[i];
+		max_allocatable_power += max_power[i];
+		total_weighted_req_power += weighted_req_power[i];
+
+		i++;
+	}
+
+	power_range = pid_controller(tz, current_temp, control_temp,
+				     max_allocatable_power);
+
+	divvy_up_power(weighted_req_power, max_power, num_actors,
+		       total_weighted_req_power, power_range, granted_power,
+		       extra_actor_power);
+
+	total_granted_power = 0;
+	i = 0;
+	list_for_each_entry(instance, &tz->thermal_instances, tz_node) {
+		if (instance->trip != trip_max_desired_temperature)
+			continue;
+
+		if (!cdev_is_power_actor(instance->cdev))
+			continue;
+
+		power_actor_set_power(instance->cdev, instance,
+				      granted_power[i]);
+		total_granted_power += granted_power[i];
+
+		i++;
+	}
+
+	trace_thermal_power_allocator(tz, req_power, total_req_power,
+				      granted_power, total_granted_power,
+				      num_actors, power_range,
+				      max_allocatable_power, current_temp,
+				      (s32)control_temp - (s32)current_temp);
+
+	kfree(req_power);
+unlock:
+	mutex_unlock(&tz->lock);
+
+	return ret;
+}
+
+static int get_governor_trips(struct thermal_zone_device *tz,
+			      struct power_allocator_params *params)
+{
+	int i, ret, last_passive;
+	bool found_first_passive;
+
+	found_first_passive = false;
+	last_passive = -1;
+	ret = -EINVAL;
+
+	for (i = 0; i < tz->trips; i++) {
+		enum thermal_trip_type type;
+
+		ret = tz->ops->get_trip_type(tz, i, &type);
+		if (ret)
+			return ret;
+
+		if (!found_first_passive) {
+			if (type == THERMAL_TRIP_PASSIVE) {
+				params->trip_switch_on = i;
+				found_first_passive = true;
+			}
+		} else if (type == THERMAL_TRIP_PASSIVE) {
+			last_passive = i;
+		} else {
+			break;
+		}
+	}
+
+	if (last_passive != -1) {
+		params->trip_max_desired_temperature = last_passive;
+		ret = 0;
+	} else {
+		ret = -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;
+	struct power_allocator_params *params = tz->governor_data;
+
+	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;
+		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;
+
+	if (!tz->tzp || !tz->tzp->sustainable_power) {
+		dev_err(&tz->device,
+			"power_allocator: missing sustainable_power\n");
+		return -EINVAL;
+	}
+
+	params = kzalloc(sizeof(*params), GFP_KERNEL);
+	if (!params)
+		return -ENOMEM;
+
+	ret = get_governor_trips(tz, params);
+	if (ret) {
+		dev_err(&tz->device,
+			"thermal zone %s has wrong trip setup for power allocator\n",
+			tz->type);
+		goto free;
+	}
+
+	ret = tz->ops->get_trip_temp(tz, params->trip_switch_on,
+				     &switch_on_temp);
+	if (ret)
+		goto free;
+
+	ret = tz->ops->get_trip_temp(tz, params->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:
+	kfree(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);
+	kfree(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 != params->trip_max_desired_temperature)
+		return 0;
+
+	ret = thermal_zone_get_temp(tz, &current_temp);
+	if (ret) {
+		dev_warn(&tz->device, "Failed to get temperature: %d\n", ret);
+		return ret;
+	}
+
+	ret = tz->ops->get_trip_temp(tz, params->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, 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, 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);
+}