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Diffstat (limited to 'include/linux/devfreq.h')
| -rw-r--r-- | include/linux/devfreq.h | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h new file mode 100644 index 00000000000..b3be3d3cbaa --- /dev/null +++ b/include/linux/devfreq.h @@ -0,0 +1,203 @@ +/* + * 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/opp.h> + +#define DEVFREQ_NAME_LEN 16 + +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_date; +}; + +/** + * 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. + * @get_dev_status The device should provide the current performance + * status to devfreq, which is used by governors. + * @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. + */ +struct devfreq_dev_profile { + unsigned long initial_freq; + unsigned int polling_ms; + + int (*target)(struct device *dev, unsigned long *freq); + int (*get_dev_status)(struct device *dev, + struct devfreq_dev_status *stat); + void (*exit)(struct device *dev); +}; + +/** + * struct devfreq_governor - Devfreq policy governor + * @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. + * @init Called when the devfreq is being attached to a device + * @exit Called when the devfreq is being removed from a + * device. Governor should stop any internal routines + * before return because related data may be + * freed after exit(). + * @no_central_polling Do not use devfreq's central polling mechanism. + * When this is set, devfreq will not call + * get_target_freq with devfreq_monitor(). However, + * devfreq will call get_target_freq with + * devfreq_update() notified by OPP framework. + * + * Note that the callbacks are called with devfreq->lock locked by devfreq. + */ +struct devfreq_governor { + const char name[DEVFREQ_NAME_LEN]; + int (*get_target_freq)(struct devfreq *this, unsigned long *freq); + int (*init)(struct devfreq *this); + void (*exit)(struct devfreq *this); + const bool no_central_polling; +}; + +/** + * 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. + * @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. + * @polling_jiffies interval in jiffies. + * @previous_freq previously configured frequency value. + * @next_polling the number of remaining jiffies to poll with + * "devfreq_monitor" executions to reevaluate + * frequency/voltage of the device. Set by + * profile's polling_ms interval. + * @data Private data of the governor. The devfreq framework does not + * touch this. + * @being_removed a flag to mark that this object is being removed in + * order to prevent trying to remove the object multiple times. + * + * 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; + struct notifier_block nb; + + unsigned long polling_jiffies; + unsigned long previous_freq; + unsigned int next_polling; + + void *data; /* private data for governors */ + + bool being_removed; +}; + +#if defined(CONFIG_PM_DEVFREQ) +extern struct devfreq *devfreq_add_device(struct device *dev, + struct devfreq_dev_profile *profile, + const struct devfreq_governor *governor, + void *data); +extern int devfreq_remove_device(struct devfreq *devfreq); + +/* Helper functions for devfreq user device driver with OPP. */ +extern struct opp *devfreq_recommended_opp(struct device *dev, + unsigned long *freq); +extern int devfreq_register_opp_notifier(struct device *dev, + struct devfreq *devfreq); +extern int devfreq_unregister_opp_notifier(struct device *dev, + struct devfreq *devfreq); + +#else /* !CONFIG_PM_DEVFREQ */ +static struct devfreq *devfreq_add_device(struct device *dev, + struct devfreq_dev_profile *profile, + struct devfreq_governor *governor, + void *data); +{ + return NULL; +} + +static int devfreq_remove_device(struct devfreq *devfreq); +{ + return 0; +} + +static struct opp *devfreq_recommended_opp(struct device *dev, + unsigned long *freq) +{ + return -EINVAL; +} + +static int devfreq_register_opp_notifier(struct device *dev, + struct devfreq *devfreq) +{ + return -EINVAL; +} + +static int devfreq_unregister_opp_notifier(struct device *dev, + struct devfreq *devfreq) +{ + return -EINVAL; +} + +#endif /* CONFIG_PM_DEVFREQ */ + +#endif /* __LINUX_DEVFREQ_H__ */ |