include/linux/devfreq.h - third_party/kernel - Git at Google

 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
  * devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework
  *	    for Non-CPU Devices.
  *
  * Copyright (C) 2011 Samsung Electronics
  *	MyungJoo Ham <myungjoo.ham@samsung.com>
  */

 #ifndef __LINUX_DEVFREQ_H__
 #define __LINUX_DEVFREQ_H__

 #include <linux/device.h>
 #include <linux/notifier.h>
 #include <linux/pm_opp.h>

 #define DEVFREQ_NAME_LEN 16

 /* DEVFREQ governor name */
 #define DEVFREQ_GOV_SIMPLE_ONDEMAND	"simple_ondemand"
 #define DEVFREQ_GOV_PERFORMANCE		"performance"
 #define DEVFREQ_GOV_POWERSAVE		"powersave"
 #define DEVFREQ_GOV_USERSPACE		"userspace"
 #define DEVFREQ_GOV_PASSIVE		"passive"

 /* DEVFREQ notifier interface */
 #define DEVFREQ_TRANSITION_NOTIFIER	(0)

 /* Transition notifiers of DEVFREQ_TRANSITION_NOTIFIER */
 #define	DEVFREQ_PRECHANGE		(0)
 #define DEVFREQ_POSTCHANGE		(1)

 struct devfreq;
 struct devfreq_governor;

 /**
  * struct devfreq_dev_status - Data given from devfreq user device to
  *			     governors. Represents the performance
  *			     statistics.
  * @total_time:		The total time represented by this instance of
  *			devfreq_dev_status
  * @busy_time:		The time that the device was working among the
  *			total_time.
  * @current_frequency:	The operating frequency.
  * @private_data:	An entry not specified by the devfreq framework.
  *			A device and a specific governor may have their
  *			own protocol with private_data. However, because
  *			this is governor-specific, a governor using this
  *			will be only compatible with devices aware of it.
  */
 struct devfreq_dev_status {
 	/* both since the last measure */
 	unsigned long total_time;
 	unsigned long busy_time;
 	unsigned long current_frequency;
 	void *private_data;
 };

 /*
  * The resulting frequency should be at most this. (this bound is the
  * least upper bound; thus, the resulting freq should be lower or same)
  * If the flag is not set, the resulting frequency should be at most the
  * bound (greatest lower bound)
  */
 #define DEVFREQ_FLAG_LEAST_UPPER_BOUND		0x1

 /**
  * struct devfreq_dev_profile - Devfreq's user device profile
  * @initial_freq:	The operating frequency when devfreq_add_device() is
  *			called.
  * @polling_ms:		The polling interval in ms. 0 disables polling.
  * @target:		The device should set its operating frequency at
  *			freq or lowest-upper-than-freq value. If freq is
  *			higher than any operable frequency, set maximum.
  *			Before returning, target function should set
  *			freq at the current frequency.
  *			The "flags" parameter's possible values are
  *			explained above with "DEVFREQ_FLAG_*" macros.
  * @get_dev_status:	The device should provide the current performance
  *			status to devfreq. Governors are recommended not to
  *			use this directly. Instead, governors are recommended
  *			to use devfreq_update_stats() along with
  *			devfreq.last_status.
  * @get_cur_freq:	The device should provide the current frequency
  *			at which it is operating.
  * @exit:		An optional callback that is called when devfreq
  *			is removing the devfreq object due to error or
  *			from devfreq_remove_device() call. If the user
  *			has registered devfreq->nb at a notifier-head,
  *			this is the time to unregister it.
  * @freq_table:		Optional list of frequencies to support statistics
  *			and freq_table must be generated in ascending order.
  * @max_state:		The size of freq_table.
  */
 struct devfreq_dev_profile {
 	unsigned long initial_freq;
 	unsigned int polling_ms;

 	int (*target)(struct device *dev, unsigned long *freq, u32 flags);
 	int (*get_dev_status)(struct device *dev,
 			      struct devfreq_dev_status *stat);
 	int (*get_cur_freq)(struct device *dev, unsigned long *freq);
 	void (*exit)(struct device *dev);

 	unsigned long *freq_table;
 	unsigned int max_state;
 };

 /**
  * struct devfreq - Device devfreq structure
  * @node:	list node - contains the devices with devfreq that have been
  *		registered.
  * @lock:	a mutex to protect accessing devfreq.
  * @dev:	device registered by devfreq class. dev.parent is the device
  *		using devfreq.
  * @profile:	device-specific devfreq profile
  * @governor:	method how to choose frequency based on the usage.
  * @governor_name:	devfreq governor name for use with this devfreq
  * @nb:		notifier block used to notify devfreq object that it should
  *		reevaluate operable frequencies. Devfreq users may use
  *		devfreq.nb to the corresponding register notifier call chain.
  * @work:	delayed work for load monitoring.
  * @previous_freq:	previously configured frequency value.
  * @data:	Private data of the governor. The devfreq framework does not
  *		touch this.
  * @min_freq:	Limit minimum frequency requested by user (0: none)
  * @max_freq:	Limit maximum frequency requested by user (0: none)
  * @scaling_min_freq:	Limit minimum frequency requested by OPP interface
  * @scaling_max_freq:	Limit maximum frequency requested by OPP interface
  * @stop_polling:	 devfreq polling status of a device.
  * @suspend_freq:	 frequency of a device set during suspend phase.
  * @resume_freq:	 frequency of a device set in resume phase.
  * @suspend_count:	 suspend requests counter for a device.
  * @total_trans:	Number of devfreq transitions
  * @trans_table:	Statistics of devfreq transitions
  * @time_in_state:	Statistics of devfreq states
  * @last_stat_updated:	The last time stat updated
  * @transition_notifier_list: list head of DEVFREQ_TRANSITION_NOTIFIER notifier
  *
  * This structure stores the devfreq information for a give device.
  *
  * Note that when a governor accesses entries in struct devfreq in its
  * functions except for the context of callbacks defined in struct
  * devfreq_governor, the governor should protect its access with the
  * struct mutex lock in struct devfreq. A governor may use this mutex
  * to protect its own private data in void *data as well.
  */
 struct devfreq {
 	struct list_head node;

 	struct mutex lock;
 	struct device dev;
 	struct devfreq_dev_profile *profile;
 	const struct devfreq_governor *governor;
 	char governor_name[DEVFREQ_NAME_LEN];
 	struct notifier_block nb;
 	struct delayed_work work;

 	unsigned long previous_freq;
 	struct devfreq_dev_status last_status;

 	void *data; /* private data for governors */

 	unsigned long min_freq;
 	unsigned long max_freq;
 	unsigned long scaling_min_freq;
 	unsigned long scaling_max_freq;
 	bool stop_polling;

 	unsigned long suspend_freq;
 	unsigned long resume_freq;
 	atomic_t suspend_count;

 	/* information for device frequency transition */
 	unsigned int total_trans;
 	unsigned int *trans_table;
 	unsigned long *time_in_state;
 	unsigned long last_stat_updated;

 	struct srcu_notifier_head transition_notifier_list;
 };

 struct devfreq_freqs {
 	unsigned long old;
 	unsigned long new;
 };

 #if defined(CONFIG_PM_DEVFREQ)
 extern struct devfreq *devfreq_add_device(struct device *dev,
 				  struct devfreq_dev_profile *profile,
 				  const char *governor_name,
 				  void *data);
 extern int devfreq_remove_device(struct devfreq *devfreq);
 extern struct devfreq *devm_devfreq_add_device(struct device *dev,
 				  struct devfreq_dev_profile *profile,
 				  const char *governor_name,
 				  void *data);
 extern void devm_devfreq_remove_device(struct device *dev,
 				  struct devfreq *devfreq);

 /* Supposed to be called by PM callbacks */
 extern int devfreq_suspend_device(struct devfreq *devfreq);
 extern int devfreq_resume_device(struct devfreq *devfreq);

 extern void devfreq_suspend(void);
 extern void devfreq_resume(void);

 /**
  * update_devfreq() - Reevaluate the device and configure frequency
  * @devfreq:	the devfreq device
  *
  * Note: devfreq->lock must be held
  */
 extern int update_devfreq(struct devfreq *devfreq);

 /* Helper functions for devfreq user device driver with OPP. */
 extern struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
 					   unsigned long *freq, u32 flags);
 extern int devfreq_register_opp_notifier(struct device *dev,
 					 struct devfreq *devfreq);
 extern int devfreq_unregister_opp_notifier(struct device *dev,
 					   struct devfreq *devfreq);
 extern int devm_devfreq_register_opp_notifier(struct device *dev,
 					      struct devfreq *devfreq);
 extern void devm_devfreq_unregister_opp_notifier(struct device *dev,
 						struct devfreq *devfreq);
 extern int devfreq_register_notifier(struct devfreq *devfreq,
 					struct notifier_block *nb,
 					unsigned int list);
 extern int devfreq_unregister_notifier(struct devfreq *devfreq,
 					struct notifier_block *nb,
 					unsigned int list);
 extern int devm_devfreq_register_notifier(struct device *dev,
 				struct devfreq *devfreq,
 				struct notifier_block *nb,
 				unsigned int list);
 extern void devm_devfreq_unregister_notifier(struct device *dev,
 				struct devfreq *devfreq,
 				struct notifier_block *nb,
 				unsigned int list);
 extern struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
 						int index);

 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
 /**
  * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
  *	and devfreq_add_device
  * @upthreshold:	If the load is over this value, the frequency jumps.
  *			Specify 0 to use the default. Valid value = 0 to 100.
  * @downdifferential:	If the load is under upthreshold - downdifferential,
  *			the governor may consider slowing the frequency down.
  *			Specify 0 to use the default. Valid value = 0 to 100.
  *			downdifferential < upthreshold must hold.
  *
  * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
  * the governor uses the default values.
  */
 struct devfreq_simple_ondemand_data {
 	unsigned int upthreshold;
 	unsigned int downdifferential;
 };
 #endif

 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE)
 /**
  * struct devfreq_passive_data - void *data fed to struct devfreq
  *	and devfreq_add_device
  * @parent:	the devfreq instance of parent device.
  * @get_target_freq:	Optional callback, Returns desired operating frequency
  *			for the device using passive governor. That is called
  *			when passive governor should decide the next frequency
  *			by using the new frequency of parent devfreq device
  *			using governors except for passive governor.
  *			If the devfreq device has the specific method to decide
  *			the next frequency, should use this callback.
  * @this:	the devfreq instance of own device.
  * @nb:		the notifier block for DEVFREQ_TRANSITION_NOTIFIER list
  *
  * The devfreq_passive_data have to set the devfreq instance of parent
  * device with governors except for the passive governor. But, don't need to
  * initialize the 'this' and 'nb' field because the devfreq core will handle
  * them.
  */
 struct devfreq_passive_data {
 	/* Should set the devfreq instance of parent device */
 	struct devfreq *parent;

 	/* Optional callback to decide the next frequency of passvice device */
 	int (*get_target_freq)(struct devfreq *this, unsigned long *freq);

 	/* For passive governor's internal use. Don't need to set them */
 	struct devfreq *this;
 	struct notifier_block nb;
 };
 #endif

 #else /* !CONFIG_PM_DEVFREQ */
 static inline struct devfreq *devfreq_add_device(struct device *dev,
 					  struct devfreq_dev_profile *profile,
 					  const char *governor_name,
 					  void *data)
 {
 	return ERR_PTR(-ENOSYS);
 }

 static inline int devfreq_remove_device(struct devfreq *devfreq)
 {
 	return 0;
 }

 static inline struct devfreq *devm_devfreq_add_device(struct device *dev,
 					struct devfreq_dev_profile *profile,
 					const char *governor_name,
 					void *data)
 {
 	return ERR_PTR(-ENOSYS);
 }

 static inline void devm_devfreq_remove_device(struct device *dev,
 					struct devfreq *devfreq)
 {
 }

 static inline int devfreq_suspend_device(struct devfreq *devfreq)
 {
 	return 0;
 }

 static inline int devfreq_resume_device(struct devfreq *devfreq)
 {
 	return 0;
 }

 static inline void devfreq_suspend(void) {}
 static inline void devfreq_resume(void) {}

 static inline struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
 					   unsigned long *freq, u32 flags)
 {
 	return ERR_PTR(-EINVAL);
 }

 static inline int devfreq_register_opp_notifier(struct device *dev,
 					 struct devfreq *devfreq)
 {
 	return -EINVAL;
 }

 static inline int devfreq_unregister_opp_notifier(struct device *dev,
 					   struct devfreq *devfreq)
 {
 	return -EINVAL;
 }

 static inline int devm_devfreq_register_opp_notifier(struct device *dev,
 						     struct devfreq *devfreq)
 {
 	return -EINVAL;
 }

 static inline void devm_devfreq_unregister_opp_notifier(struct device *dev,
 							struct devfreq *devfreq)
 {
 }

 static inline int devfreq_register_notifier(struct devfreq *devfreq,
 					struct notifier_block *nb,
 					unsigned int list)
 {
 	return 0;
 }

 static inline int devfreq_unregister_notifier(struct devfreq *devfreq,
 					struct notifier_block *nb,
 					unsigned int list)
 {
 	return 0;
 }

 static inline int devm_devfreq_register_notifier(struct device *dev,
 				struct devfreq *devfreq,
 				struct notifier_block *nb,
 				unsigned int list)
 {
 	return 0;
 }

 static inline void devm_devfreq_unregister_notifier(struct device *dev,
 				struct devfreq *devfreq,
 				struct notifier_block *nb,
 				unsigned int list)
 {
 }

 static inline struct devfreq *devfreq_get_devfreq_by_phandle(struct device *dev,
 							int index)
 {
 	return ERR_PTR(-ENODEV);
 }

 static inline int devfreq_update_stats(struct devfreq *df)
 {
 	return -EINVAL;
 }
 #endif /* CONFIG_PM_DEVFREQ */

 #endif /* __LINUX_DEVFREQ_H__ */
	/* SPDX-License-Identifier: GPL-2.0-only */
	/*
	* devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework
	* for Non-CPU Devices.
	*
	* Copyright (C) 2011 Samsung Electronics
	* MyungJoo Ham <myungjoo.ham@samsung.com>
	*/

	#ifndef __LINUX_DEVFREQ_H__
	#define __LINUX_DEVFREQ_H__

	#include <linux/device.h>
	#include <linux/notifier.h>
	#include <linux/pm_opp.h>

	#define DEVFREQ_NAME_LEN 16

	/* DEVFREQ governor name */
	#define DEVFREQ_GOV_SIMPLE_ONDEMAND "simple_ondemand"
	#define DEVFREQ_GOV_PERFORMANCE "performance"
	#define DEVFREQ_GOV_POWERSAVE "powersave"
	#define DEVFREQ_GOV_USERSPACE "userspace"
	#define DEVFREQ_GOV_PASSIVE "passive"

	/* DEVFREQ notifier interface */
	#define DEVFREQ_TRANSITION_NOTIFIER (0)

	/* Transition notifiers of DEVFREQ_TRANSITION_NOTIFIER */
	#define DEVFREQ_PRECHANGE (0)
	#define DEVFREQ_POSTCHANGE (1)

	struct devfreq;
	struct devfreq_governor;

	/**
	* struct devfreq_dev_status - Data given from devfreq user device to
	* governors. Represents the performance
	* statistics.
	* @total_time: The total time represented by this instance of
	* devfreq_dev_status
	* @busy_time: The time that the device was working among the
	* total_time.
	* @current_frequency: The operating frequency.
	* @private_data: An entry not specified by the devfreq framework.
	* A device and a specific governor may have their
	* own protocol with private_data. However, because
	* this is governor-specific, a governor using this
	* will be only compatible with devices aware of it.
	*/
	struct devfreq_dev_status {
	/* both since the last measure */
	unsigned long total_time;
	unsigned long busy_time;
	unsigned long current_frequency;
	void *private_data;
	};

	/*
	* The resulting frequency should be at most this. (this bound is the
	* least upper bound; thus, the resulting freq should be lower or same)
	* If the flag is not set, the resulting frequency should be at most the
	* bound (greatest lower bound)
	*/
	#define DEVFREQ_FLAG_LEAST_UPPER_BOUND 0x1

	/**
	* struct devfreq_dev_profile - Devfreq's user device profile
	* @initial_freq: The operating frequency when devfreq_add_device() is
	* called.
	* @polling_ms: The polling interval in ms. 0 disables polling.
	* @target: The device should set its operating frequency at
	* freq or lowest-upper-than-freq value. If freq is
	* higher than any operable frequency, set maximum.
	* Before returning, target function should set
	* freq at the current frequency.
	* The "flags" parameter's possible values are
	* explained above with "DEVFREQ_FLAG_*" macros.
	* @get_dev_status: The device should provide the current performance
	* status to devfreq. Governors are recommended not to
	* use this directly. Instead, governors are recommended
	* to use devfreq_update_stats() along with
	* devfreq.last_status.
	* @get_cur_freq: The device should provide the current frequency
	* at which it is operating.
	* @exit: An optional callback that is called when devfreq
	* is removing the devfreq object due to error or
	* from devfreq_remove_device() call. If the user
	* has registered devfreq->nb at a notifier-head,
	* this is the time to unregister it.
	* @freq_table: Optional list of frequencies to support statistics
	* and freq_table must be generated in ascending order.
	* @max_state: The size of freq_table.
	*/
	struct devfreq_dev_profile {
	unsigned long initial_freq;
	unsigned int polling_ms;

	int (target)(struct device dev, unsigned long *freq, u32 flags);
	int (get_dev_status)(struct device dev,
	struct devfreq_dev_status *stat);
	int (get_cur_freq)(struct device dev, unsigned long *freq);
	void (exit)(struct device dev);

	unsigned long *freq_table;
	unsigned int max_state;
	};

	/**
	* struct devfreq - Device devfreq structure
	* @node: list node - contains the devices with devfreq that have been
	* registered.
	* @lock: a mutex to protect accessing devfreq.
	* @dev: device registered by devfreq class. dev.parent is the device
	* using devfreq.
	* @profile: device-specific devfreq profile
	* @governor: method how to choose frequency based on the usage.
	* @governor_name: devfreq governor name for use with this devfreq
	* @nb: notifier block used to notify devfreq object that it should
	* reevaluate operable frequencies. Devfreq users may use
	* devfreq.nb to the corresponding register notifier call chain.
	* @work: delayed work for load monitoring.
	* @previous_freq: previously configured frequency value.
	* @data: Private data of the governor. The devfreq framework does not
	* touch this.
	* @min_freq: Limit minimum frequency requested by user (0: none)
	* @max_freq: Limit maximum frequency requested by user (0: none)
	* @scaling_min_freq: Limit minimum frequency requested by OPP interface
	* @scaling_max_freq: Limit maximum frequency requested by OPP interface
	* @stop_polling: devfreq polling status of a device.
	* @suspend_freq: frequency of a device set during suspend phase.
	* @resume_freq: frequency of a device set in resume phase.
	* @suspend_count: suspend requests counter for a device.
	* @total_trans: Number of devfreq transitions
	* @trans_table: Statistics of devfreq transitions
	* @time_in_state: Statistics of devfreq states
	* @last_stat_updated: The last time stat updated
	* @transition_notifier_list: list head of DEVFREQ_TRANSITION_NOTIFIER notifier
	*
	* This structure stores the devfreq information for a give device.
	*
	* Note that when a governor accesses entries in struct devfreq in its
	* functions except for the context of callbacks defined in struct
	* devfreq_governor, the governor should protect its access with the
	* struct mutex lock in struct devfreq. A governor may use this mutex
	* to protect its own private data in void *data as well.
	*/
	struct devfreq {
	struct list_head node;

	struct mutex lock;
	struct device dev;
	struct devfreq_dev_profile *profile;
	const struct devfreq_governor *governor;
	char governor_name[DEVFREQ_NAME_LEN];
	struct notifier_block nb;
	struct delayed_work work;

	unsigned long previous_freq;
	struct devfreq_dev_status last_status;

	void data; / private data for governors */

	unsigned long min_freq;
	unsigned long max_freq;
	unsigned long scaling_min_freq;
	unsigned long scaling_max_freq;
	bool stop_polling;

	unsigned long suspend_freq;
	unsigned long resume_freq;
	atomic_t suspend_count;

	/* information for device frequency transition */
	unsigned int total_trans;
	unsigned int *trans_table;
	unsigned long *time_in_state;
	unsigned long last_stat_updated;

	struct srcu_notifier_head transition_notifier_list;
	};

	struct devfreq_freqs {
	unsigned long old;
	unsigned long new;
	};

	#if defined(CONFIG_PM_DEVFREQ)
	extern struct devfreq devfreq_add_device(struct device dev,
	struct devfreq_dev_profile *profile,
	const char *governor_name,
	void *data);
	extern int devfreq_remove_device(struct devfreq *devfreq);
	extern struct devfreq devm_devfreq_add_device(struct device dev,
	struct devfreq_dev_profile *profile,
	const char *governor_name,
	void *data);
	extern void devm_devfreq_remove_device(struct device *dev,
	struct devfreq *devfreq);

	/* Supposed to be called by PM callbacks */
	extern int devfreq_suspend_device(struct devfreq *devfreq);
	extern int devfreq_resume_device(struct devfreq *devfreq);

	extern void devfreq_suspend(void);
	extern void devfreq_resume(void);

	/**
	* update_devfreq() - Reevaluate the device and configure frequency
	* @devfreq: the devfreq device
	*
	* Note: devfreq->lock must be held
	*/
	extern int update_devfreq(struct devfreq *devfreq);

	/* Helper functions for devfreq user device driver with OPP. */
	extern struct dev_pm_opp devfreq_recommended_opp(struct device dev,
	unsigned long *freq, u32 flags);
	extern int devfreq_register_opp_notifier(struct device *dev,
	struct devfreq *devfreq);
	extern int devfreq_unregister_opp_notifier(struct device *dev,
	struct devfreq *devfreq);
	extern int devm_devfreq_register_opp_notifier(struct device *dev,
	struct devfreq *devfreq);
	extern void devm_devfreq_unregister_opp_notifier(struct device *dev,
	struct devfreq *devfreq);
	extern int devfreq_register_notifier(struct devfreq *devfreq,
	struct notifier_block *nb,
	unsigned int list);
	extern int devfreq_unregister_notifier(struct devfreq *devfreq,
	struct notifier_block *nb,
	unsigned int list);
	extern int devm_devfreq_register_notifier(struct device *dev,
	struct devfreq *devfreq,
	struct notifier_block *nb,
	unsigned int list);
	extern void devm_devfreq_unregister_notifier(struct device *dev,
	struct devfreq *devfreq,
	struct notifier_block *nb,
	unsigned int list);
	extern struct devfreq devfreq_get_devfreq_by_phandle(struct device dev,
	int index);

	#if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
	/**
	* struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
	* and devfreq_add_device
	* @upthreshold: If the load is over this value, the frequency jumps.
	* Specify 0 to use the default. Valid value = 0 to 100.
	* @downdifferential: If the load is under upthreshold - downdifferential,
	* the governor may consider slowing the frequency down.
	* Specify 0 to use the default. Valid value = 0 to 100.
	* downdifferential < upthreshold must hold.
	*
	* If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
	* the governor uses the default values.
	*/
	struct devfreq_simple_ondemand_data {
	unsigned int upthreshold;
	unsigned int downdifferential;
	};
	#endif

	#if IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE)
	/**
	* struct devfreq_passive_data - void *data fed to struct devfreq
	* and devfreq_add_device
	* @parent: the devfreq instance of parent device.
	* @get_target_freq: Optional callback, Returns desired operating frequency
	* for the device using passive governor. That is called
	* when passive governor should decide the next frequency
	* by using the new frequency of parent devfreq device
	* using governors except for passive governor.
	* If the devfreq device has the specific method to decide
	* the next frequency, should use this callback.
	* @this: the devfreq instance of own device.
	* @nb: the notifier block for DEVFREQ_TRANSITION_NOTIFIER list
	*
	* The devfreq_passive_data have to set the devfreq instance of parent
	* device with governors except for the passive governor. But, don't need to
	* initialize the 'this' and 'nb' field because the devfreq core will handle
	* them.
	*/
	struct devfreq_passive_data {
	/* Should set the devfreq instance of parent device */
	struct devfreq *parent;

	/* Optional callback to decide the next frequency of passvice device */
	int (get_target_freq)(struct devfreq this, unsigned long *freq);

	/* For passive governor's internal use. Don't need to set them */
	struct devfreq *this;
	struct notifier_block nb;
	};
	#endif

	#else /* !CONFIG_PM_DEVFREQ */
	static inline struct devfreq devfreq_add_device(struct device dev,
	struct devfreq_dev_profile *profile,
	const char *governor_name,
	void *data)
	{
	return ERR_PTR(-ENOSYS);
	}

	static inline int devfreq_remove_device(struct devfreq *devfreq)
	{
	return 0;
	}

	static inline struct devfreq devm_devfreq_add_device(struct device dev,
	struct devfreq_dev_profile *profile,
	const char *governor_name,
	void *data)
	{
	return ERR_PTR(-ENOSYS);
	}

	static inline void devm_devfreq_remove_device(struct device *dev,
	struct devfreq *devfreq)
	{
	}

	static inline int devfreq_suspend_device(struct devfreq *devfreq)
	{
	return 0;
	}

	static inline int devfreq_resume_device(struct devfreq *devfreq)
	{
	return 0;
	}

	static inline void devfreq_suspend(void) {}
	static inline void devfreq_resume(void) {}

	static inline struct dev_pm_opp devfreq_recommended_opp(struct device dev,
	unsigned long *freq, u32 flags)
	{
	return ERR_PTR(-EINVAL);
	}

	static inline int devfreq_register_opp_notifier(struct device *dev,
	struct devfreq *devfreq)
	{
	return -EINVAL;
	}

	static inline int devfreq_unregister_opp_notifier(struct device *dev,
	struct devfreq *devfreq)
	{
	return -EINVAL;
	}

	static inline int devm_devfreq_register_opp_notifier(struct device *dev,
	struct devfreq *devfreq)
	{
	return -EINVAL;
	}

	static inline void devm_devfreq_unregister_opp_notifier(struct device *dev,
	struct devfreq *devfreq)
	{
	}

	static inline int devfreq_register_notifier(struct devfreq *devfreq,
	struct notifier_block *nb,
	unsigned int list)
	{
	return 0;
	}

	static inline int devfreq_unregister_notifier(struct devfreq *devfreq,
	struct notifier_block *nb,
	unsigned int list)
	{
	return 0;
	}

	static inline int devm_devfreq_register_notifier(struct device *dev,
	struct devfreq *devfreq,
	struct notifier_block *nb,
	unsigned int list)
	{
	return 0;
	}

	static inline void devm_devfreq_unregister_notifier(struct device *dev,
	struct devfreq *devfreq,
	struct notifier_block *nb,
	unsigned int list)
	{
	}

	static inline struct devfreq devfreq_get_devfreq_by_phandle(struct device dev,
	int index)
	{
	return ERR_PTR(-ENODEV);
	}

	static inline int devfreq_update_stats(struct devfreq *df)
	{
	return -EINVAL;
	}
	#endif /* CONFIG_PM_DEVFREQ */

	#endif /* __LINUX_DEVFREQ_H__ */