254 lines
8.6 KiB
C
254 lines
8.6 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_data;
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};
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/*
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* The resulting frequency should be at most this. (this bound is the
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* least upper bound; thus, the resulting freq should be lower or same)
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* If the flag is not set, the resulting frequency should be at most the
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* bound (greatest lower bound)
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*/
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#define DEVFREQ_FLAG_LEAST_UPPER_BOUND 0x1
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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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* The "flags" parameter's possible values are
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* explained above with "DEVFREQ_FLAG_*" macros.
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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, u32 flags);
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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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* @min_freq Limit minimum frequency requested by user (0: none)
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* @max_freq Limit maximum frequency requested by user (0: none)
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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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unsigned long min_freq;
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unsigned long max_freq;
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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, u32 flags);
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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, u32 flags)
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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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