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linux-next/include/linux/devfreq.h
Chanwoo Choi 996133119f PM / devfreq: Add new passive governor
This patch adds the new passive governor for DEVFREQ framework. The following
governors are already present and used for DVFS (Dynamic Voltage and Frequency
Scaling) drivers. The following governors are independently used for one device
driver which don't give the influence to other device drviers and also don't
receive the effect from other device drivers.
- ondemand / performance / powersave / userspace

The passive governor depends on operation of parent driver with specific
governos extremely and is not able to decide the new frequency by oneself.
According to the decided new frequency of parent driver with governor,
the passive governor uses it to decide the appropriate frequency for own
device driver. The passive governor must need the following information
from device tree:
- the source clock and OPP tables
- the instance of parent device

For exameple,
there are one more devfreq device drivers which need to change their source
clock according to their utilization on runtime. But, they share the same
power line (e.g., regulator). So, specific device driver is operated as parent
with ondemand governor and then the rest device driver with passive governor
is influenced by parent device.

Suggested-by: Myungjoo Ham <myungjoo.ham@samsung.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
[tjakobi: Reported RCU locking issue and cw00.choi fix it]
Reported-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
[linux.amoon: Reported possible recursive locking and cw00.choi fix it]
Reported-by: Anand Moon <linux.amoon@gmail.com>
Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
Acked-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
2016-05-03 11:20:07 +09:00

416 lines
14 KiB
C

/*
* devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework
* for Non-CPU Devices.
*
* Copyright (C) 2011 Samsung Electronics
* MyungJoo Ham <myungjoo.ham@samsung.com>
*
* 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.
*/
#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 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_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.
* @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_governor - Devfreq policy governor
* @node: list node - contains registered devfreq governors
* @name: Governor's name
* @get_target_freq: Returns desired operating frequency for the device.
* Basically, get_target_freq will run
* devfreq_dev_profile.get_dev_status() to get the
* status of the device (load = busy_time / total_time).
* If no_central_polling is set, this callback is called
* only with update_devfreq() notified by OPP.
* @event_handler: Callback for devfreq core framework to notify events
* to governors. Events include per device governor
* init and exit, opp changes out of devfreq, suspend
* and resume of per device devfreq during device idle.
*
* Note that the callbacks are called with devfreq->lock locked by devfreq.
*/
struct devfreq_governor {
struct list_head node;
const char name[DEVFREQ_NAME_LEN];
int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
int (*event_handler)(struct devfreq *devfreq,
unsigned int event, void *data);
};
/**
* 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)
* @stop_polling: devfreq polling status of 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;
bool stop_polling;
/* 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);
/* 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);
/**
* devfreq_update_stats() - update the last_status pointer in struct devfreq
* @df: the devfreq instance whose status needs updating
*
* Governors are recommended to use this function along with last_status,
* which allows other entities to reuse the last_status without affecting
* the values fetched later by governors.
*/
static inline int devfreq_update_stats(struct devfreq *df)
{
return df->profile->get_dev_status(df->dev.parent, &df->last_status);
}
#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 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__ */