7e6fdd4bad
Prepare devfreq core framework to support devices which can idle. When device idleness is detected perhaps through runtime-pm, need some mechanism to suspend devfreq load monitoring and resume back when device is online. Present code continues monitoring unless device is removed from devfreq core. This patch introduces following design changes, - use per device work instead of global work to monitor device load. This enables suspend/resume of device devfreq and reduces monitoring code complexity. - decouple delayed work based load monitoring logic from core by introducing helpers functions to be used by governors. This provides flexibility for governors either to use delayed work based monitoring functions or to implement their own mechanism. - devfreq core interacts with governors via events to perform specific actions. These events include start/stop devfreq. This sets ground for adding suspend/resume events. The devfreq apis are not modified and are kept intact. Signed-off-by: Rajagopal Venkat <rajagopal.venkat@linaro.org> Acked-by: MyungJoo Ham <myungjoo.ham@samsung.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
240 lines
8 KiB
C
240 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_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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* @event_handler Callback for devfreq core framework to notify events
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* to governors. Events include per device governor
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* init and exit, opp changes out of devfreq, suspend
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* and resume of per device devfreq during device idle.
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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 (*event_handler)(struct devfreq *devfreq,
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unsigned int event, void *data);
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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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* @work delayed work for load monitoring.
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* @previous_freq previously configured frequency value.
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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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* @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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* @stop_polling devfreq polling status of a device.
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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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struct delayed_work work;
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unsigned long previous_freq;
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void *data; /* private data for governors */
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unsigned long min_freq;
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unsigned long max_freq;
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bool stop_polling;
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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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