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2be83da85a
This patch introduces a new interface for device drivers connected to
devfreq_cooling in the thermal framework: get_real_power().
Some devices have more sophisticated methods (like power counters)
to approximate the actual power that they use.
In the previous implementation we had a pre-calculated power
table which was then scaled by 'utilization'
('busy_time' and 'total_time' taken from devfreq 'last_status').
With this new interface the driver can provide more precise data
regarding actual power to the thermal governor every time the power
budget is calculated. We then use this value and calculate the real
resource utilization scaling factor.
Reviewed-by: Chris Diamand <chris.diamand@arm.com>
Acked-by: Javi Merino <javi.merino@kernel.org>
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
104 lines
3.5 KiB
C
104 lines
3.5 KiB
C
/*
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* devfreq_cooling: Thermal cooling device implementation for devices using
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* devfreq
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*
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* Copyright (C) 2014-2015 ARM Limited
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed "as is" WITHOUT ANY WARRANTY of any
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* kind, whether express or implied; without even the implied warranty
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* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#ifndef __DEVFREQ_COOLING_H__
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#define __DEVFREQ_COOLING_H__
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#include <linux/devfreq.h>
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#include <linux/thermal.h>
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/**
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* struct devfreq_cooling_power - Devfreq cooling power ops
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* @get_static_power: Take voltage, in mV, and return the static power
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* in mW. If NULL, the static power is assumed
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* to be 0.
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* @get_dynamic_power: Take voltage, in mV, and frequency, in HZ, and
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* return the dynamic power draw in mW. If NULL,
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* a simple power model is used.
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* @dyn_power_coeff: Coefficient for the simple dynamic power model in
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* mW/(MHz mV mV).
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* If get_dynamic_power() is NULL, then the
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* dynamic power is calculated as
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* @dyn_power_coeff * frequency * voltage^2
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* @get_real_power: When this is set, the framework uses it to ask the
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* device driver for the actual power.
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* Some devices have more sophisticated methods
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* (like power counters) to approximate the actual power
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* that they use.
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* This function provides more accurate data to the
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* thermal governor. When the driver does not provide
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* such function, framework just uses pre-calculated
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* table and scale the power by 'utilization'
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* (based on 'busy_time' and 'total_time' taken from
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* devfreq 'last_status').
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* The value returned by this function must be lower
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* or equal than the maximum power value
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* for the current state
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* (which can be found in power_table[state]).
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* When this interface is used, the power_table holds
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* max total (static + dynamic) power value for each OPP.
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*/
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struct devfreq_cooling_power {
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unsigned long (*get_static_power)(struct devfreq *devfreq,
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unsigned long voltage);
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unsigned long (*get_dynamic_power)(struct devfreq *devfreq,
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unsigned long freq,
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unsigned long voltage);
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int (*get_real_power)(struct devfreq *df, u32 *power,
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unsigned long freq, unsigned long voltage);
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unsigned long dyn_power_coeff;
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};
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#ifdef CONFIG_DEVFREQ_THERMAL
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struct thermal_cooling_device *
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of_devfreq_cooling_register_power(struct device_node *np, struct devfreq *df,
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struct devfreq_cooling_power *dfc_power);
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struct thermal_cooling_device *
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of_devfreq_cooling_register(struct device_node *np, struct devfreq *df);
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struct thermal_cooling_device *devfreq_cooling_register(struct devfreq *df);
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void devfreq_cooling_unregister(struct thermal_cooling_device *dfc);
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#else /* !CONFIG_DEVFREQ_THERMAL */
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struct thermal_cooling_device *
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of_devfreq_cooling_register_power(struct device_node *np, struct devfreq *df,
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struct devfreq_cooling_power *dfc_power)
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{
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return ERR_PTR(-EINVAL);
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}
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static inline struct thermal_cooling_device *
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of_devfreq_cooling_register(struct device_node *np, struct devfreq *df)
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{
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return ERR_PTR(-EINVAL);
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}
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static inline struct thermal_cooling_device *
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devfreq_cooling_register(struct devfreq *df)
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{
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return ERR_PTR(-EINVAL);
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}
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static inline void
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devfreq_cooling_unregister(struct thermal_cooling_device *dfc)
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{
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}
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#endif /* CONFIG_DEVFREQ_THERMAL */
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#endif /* __DEVFREQ_COOLING_H__ */
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