ce26c5bb95
Four cpufreq-like governors are provided as examples. powersave: use the lowest frequency possible. The user (device) should set the polling_ms as 0 because polling is useless for this governor. performance: use the highest freqeuncy possible. The user (device) should set the polling_ms as 0 because polling is useless for this governor. userspace: use the user specified frequency stored at devfreq.user_set_freq. With sysfs support in the following patch, a user may set the value with the sysfs interface. simple_ondemand: simplified version of cpufreq's ondemand governor. When a user updates OPP entries (enable/disable/add), OPP framework automatically notifies devfreq to update operating frequency accordingly. Thus, devfreq users (device drivers) do not need to update devfreq manually with OPP entry updates or set polling_ms for powersave , performance, userspace, or any other "static" governors. Note that these are given only as basic examples for governors and any devices with devfreq may implement their own governors with the drivers and use them. Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com> Reviewed-by: Mike Turquette <mturquette@ti.com> Acked-by: Kevin Hilman <khilman@ti.com> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
239 lines
8 KiB
C
239 lines
8 KiB
C
/*
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* devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework
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* for Non-CPU Devices.
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*
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* Copyright (C) 2011 Samsung Electronics
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* MyungJoo Ham <myungjoo.ham@samsung.com>
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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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#ifndef __LINUX_DEVFREQ_H__
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#define __LINUX_DEVFREQ_H__
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#include <linux/device.h>
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#include <linux/notifier.h>
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#include <linux/opp.h>
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#define DEVFREQ_NAME_LEN 16
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struct devfreq;
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/**
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* struct devfreq_dev_status - Data given from devfreq user device to
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* governors. Represents the performance
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* statistics.
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* @total_time The total time represented by this instance of
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* devfreq_dev_status
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* @busy_time The time that the device was working among the
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* total_time.
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* @current_frequency The operating frequency.
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* @private_data An entry not specified by the devfreq framework.
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* A device and a specific governor may have their
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* own protocol with private_data. However, because
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* this is governor-specific, a governor using this
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* will be only compatible with devices aware of it.
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*/
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struct devfreq_dev_status {
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/* both since the last measure */
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unsigned long total_time;
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unsigned long busy_time;
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unsigned long current_frequency;
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void *private_date;
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};
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/**
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* struct devfreq_dev_profile - Devfreq's user device profile
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* @initial_freq The operating frequency when devfreq_add_device() is
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* called.
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* @polling_ms The polling interval in ms. 0 disables polling.
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* @target The device should set its operating frequency at
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* freq or lowest-upper-than-freq value. If freq is
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* higher than any operable frequency, set maximum.
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* Before returning, target function should set
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* freq at the current frequency.
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* @get_dev_status The device should provide the current performance
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* status to devfreq, which is used by governors.
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* @exit An optional callback that is called when devfreq
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* is removing the devfreq object due to error or
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* from devfreq_remove_device() call. If the user
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* has registered devfreq->nb at a notifier-head,
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* this is the time to unregister it.
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*/
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struct devfreq_dev_profile {
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unsigned long initial_freq;
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unsigned int polling_ms;
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int (*target)(struct device *dev, unsigned long *freq);
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int (*get_dev_status)(struct device *dev,
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struct devfreq_dev_status *stat);
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void (*exit)(struct device *dev);
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};
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/**
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* struct devfreq_governor - Devfreq policy governor
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* @name Governor's name
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* @get_target_freq Returns desired operating frequency for the device.
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* Basically, get_target_freq will run
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* devfreq_dev_profile.get_dev_status() to get the
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* status of the device (load = busy_time / total_time).
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* If no_central_polling is set, this callback is called
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* only with update_devfreq() notified by OPP.
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* @init Called when the devfreq is being attached to a device
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* @exit Called when the devfreq is being removed from a
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* device. Governor should stop any internal routines
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* before return because related data may be
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* freed after exit().
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* @no_central_polling Do not use devfreq's central polling mechanism.
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* When this is set, devfreq will not call
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* get_target_freq with devfreq_monitor(). However,
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* devfreq will call get_target_freq with
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* devfreq_update() notified by OPP framework.
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*
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* Note that the callbacks are called with devfreq->lock locked by devfreq.
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*/
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struct devfreq_governor {
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const char name[DEVFREQ_NAME_LEN];
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int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
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int (*init)(struct devfreq *this);
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void (*exit)(struct devfreq *this);
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const bool no_central_polling;
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};
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/**
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* struct devfreq - Device devfreq structure
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* @node list node - contains the devices with devfreq that have been
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* registered.
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* @lock a mutex to protect accessing devfreq.
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* @dev device registered by devfreq class. dev.parent is the device
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* using devfreq.
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* @profile device-specific devfreq profile
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* @governor method how to choose frequency based on the usage.
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* @nb notifier block used to notify devfreq object that it should
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* reevaluate operable frequencies. Devfreq users may use
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* devfreq.nb to the corresponding register notifier call chain.
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* @polling_jiffies interval in jiffies.
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* @previous_freq previously configured frequency value.
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* @next_polling the number of remaining jiffies to poll with
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* "devfreq_monitor" executions to reevaluate
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* frequency/voltage of the device. Set by
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* profile's polling_ms interval.
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* @data Private data of the governor. The devfreq framework does not
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* touch this.
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* @being_removed a flag to mark that this object is being removed in
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* order to prevent trying to remove the object multiple times.
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*
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* This structure stores the devfreq information for a give device.
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*
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* Note that when a governor accesses entries in struct devfreq in its
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* functions except for the context of callbacks defined in struct
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* devfreq_governor, the governor should protect its access with the
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* struct mutex lock in struct devfreq. A governor may use this mutex
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* to protect its own private data in void *data as well.
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*/
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struct devfreq {
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struct list_head node;
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struct mutex lock;
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struct device dev;
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struct devfreq_dev_profile *profile;
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const struct devfreq_governor *governor;
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struct notifier_block nb;
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unsigned long polling_jiffies;
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unsigned long previous_freq;
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unsigned int next_polling;
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void *data; /* private data for governors */
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bool being_removed;
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};
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#if defined(CONFIG_PM_DEVFREQ)
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extern struct devfreq *devfreq_add_device(struct device *dev,
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struct devfreq_dev_profile *profile,
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const struct devfreq_governor *governor,
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void *data);
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extern int devfreq_remove_device(struct devfreq *devfreq);
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/* Helper functions for devfreq user device driver with OPP. */
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extern struct opp *devfreq_recommended_opp(struct device *dev,
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unsigned long *freq);
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extern int devfreq_register_opp_notifier(struct device *dev,
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struct devfreq *devfreq);
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extern int devfreq_unregister_opp_notifier(struct device *dev,
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struct devfreq *devfreq);
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#ifdef CONFIG_DEVFREQ_GOV_POWERSAVE
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extern const struct devfreq_governor devfreq_powersave;
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#endif
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#ifdef CONFIG_DEVFREQ_GOV_PERFORMANCE
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extern const struct devfreq_governor devfreq_performance;
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#endif
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#ifdef CONFIG_DEVFREQ_GOV_USERSPACE
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extern const struct devfreq_governor devfreq_userspace;
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#endif
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#ifdef CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND
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extern const struct devfreq_governor devfreq_simple_ondemand;
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/**
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* struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
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* and devfreq_add_device
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* @ upthreshold If the load is over this value, the frequency jumps.
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* Specify 0 to use the default. Valid value = 0 to 100.
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* @ downdifferential If the load is under upthreshold - downdifferential,
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* the governor may consider slowing the frequency down.
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* Specify 0 to use the default. Valid value = 0 to 100.
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* downdifferential < upthreshold must hold.
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*
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* If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
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* the governor uses the default values.
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*/
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struct devfreq_simple_ondemand_data {
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unsigned int upthreshold;
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unsigned int downdifferential;
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};
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#endif
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#else /* !CONFIG_PM_DEVFREQ */
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static struct devfreq *devfreq_add_device(struct device *dev,
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struct devfreq_dev_profile *profile,
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struct devfreq_governor *governor,
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void *data);
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{
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return NULL;
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}
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static int devfreq_remove_device(struct devfreq *devfreq);
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{
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return 0;
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}
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static struct opp *devfreq_recommended_opp(struct device *dev,
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unsigned long *freq)
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{
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return -EINVAL;
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}
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static int devfreq_register_opp_notifier(struct device *dev,
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struct devfreq *devfreq)
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{
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return -EINVAL;
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}
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static int devfreq_unregister_opp_notifier(struct device *dev,
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struct devfreq *devfreq)
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{
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return -EINVAL;
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}
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#define devfreq_powersave NULL
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#define devfreq_performance NULL
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#define devfreq_userspace NULL
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#define devfreq_simple_ondemand NULL
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#endif /* CONFIG_PM_DEVFREQ */
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#endif /* __LINUX_DEVFREQ_H__ */
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