2 * devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework
5 * Copyright (C) 2011 Samsung Electronics
6 * MyungJoo Ham <myungjoo.ham@samsung.com>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
13 #ifndef __LINUX_DEVFREQ_H__
14 #define __LINUX_DEVFREQ_H__
16 #include <linux/device.h>
17 #include <linux/notifier.h>
18 #include <linux/opp.h>
20 #define DEVFREQ_NAME_LEN 16
25 * struct devfreq_dev_status - Data given from devfreq user device to
26 * governors. Represents the performance
28 * @total_time The total time represented by this instance of
30 * @busy_time The time that the device was working among the
32 * @current_frequency The operating frequency.
33 * @private_data An entry not specified by the devfreq framework.
34 * A device and a specific governor may have their
35 * own protocol with private_data. However, because
36 * this is governor-specific, a governor using this
37 * will be only compatible with devices aware of it.
39 struct devfreq_dev_status {
40 /* both since the last measure */
41 unsigned long total_time;
42 unsigned long busy_time;
43 unsigned long current_frequency;
48 * struct devfreq_dev_profile - Devfreq's user device profile
49 * @initial_freq The operating frequency when devfreq_add_device() is
51 * @polling_ms The polling interval in ms. 0 disables polling.
52 * @target The device should set its operating frequency at
53 * freq or lowest-upper-than-freq value. If freq is
54 * higher than any operable frequency, set maximum.
55 * Before returning, target function should set
56 * freq at the current frequency.
57 * @get_dev_status The device should provide the current performance
58 * status to devfreq, which is used by governors.
59 * @exit An optional callback that is called when devfreq
60 * is removing the devfreq object due to error or
61 * from devfreq_remove_device() call. If the user
62 * has registered devfreq->nb at a notifier-head,
63 * this is the time to unregister it.
65 struct devfreq_dev_profile {
66 unsigned long initial_freq;
67 unsigned int polling_ms;
69 int (*target)(struct device *dev, unsigned long *freq);
70 int (*get_dev_status)(struct device *dev,
71 struct devfreq_dev_status *stat);
72 void (*exit)(struct device *dev);
76 * struct devfreq_governor - Devfreq policy governor
77 * @name Governor's name
78 * @get_target_freq Returns desired operating frequency for the device.
79 * Basically, get_target_freq will run
80 * devfreq_dev_profile.get_dev_status() to get the
81 * status of the device (load = busy_time / total_time).
82 * If no_central_polling is set, this callback is called
83 * only with update_devfreq() notified by OPP.
84 * @init Called when the devfreq is being attached to a device
85 * @exit Called when the devfreq is being removed from a
86 * device. Governor should stop any internal routines
87 * before return because related data may be
89 * @no_central_polling Do not use devfreq's central polling mechanism.
90 * When this is set, devfreq will not call
91 * get_target_freq with devfreq_monitor(). However,
92 * devfreq will call get_target_freq with
93 * devfreq_update() notified by OPP framework.
95 * Note that the callbacks are called with devfreq->lock locked by devfreq.
97 struct devfreq_governor {
98 const char name[DEVFREQ_NAME_LEN];
99 int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
100 int (*init)(struct devfreq *this);
101 void (*exit)(struct devfreq *this);
102 const bool no_central_polling;
106 * struct devfreq - Device devfreq structure
107 * @node list node - contains the devices with devfreq that have been
109 * @lock a mutex to protect accessing devfreq.
110 * @dev device registered by devfreq class. dev.parent is the device
112 * @profile device-specific devfreq profile
113 * @governor method how to choose frequency based on the usage.
114 * @nb notifier block used to notify devfreq object that it should
115 * reevaluate operable frequencies. Devfreq users may use
116 * devfreq.nb to the corresponding register notifier call chain.
117 * @polling_jiffies interval in jiffies.
118 * @previous_freq previously configured frequency value.
119 * @next_polling the number of remaining jiffies to poll with
120 * "devfreq_monitor" executions to reevaluate
121 * frequency/voltage of the device. Set by
122 * profile's polling_ms interval.
123 * @data Private data of the governor. The devfreq framework does not
125 * @being_removed a flag to mark that this object is being removed in
126 * order to prevent trying to remove the object multiple times.
127 * @min_freq Limit minimum frequency requested by user (0: none)
128 * @max_freq Limit maximum frequency requested by user (0: none)
130 * This structure stores the devfreq information for a give device.
132 * Note that when a governor accesses entries in struct devfreq in its
133 * functions except for the context of callbacks defined in struct
134 * devfreq_governor, the governor should protect its access with the
135 * struct mutex lock in struct devfreq. A governor may use this mutex
136 * to protect its own private data in void *data as well.
139 struct list_head node;
143 struct devfreq_dev_profile *profile;
144 const struct devfreq_governor *governor;
145 struct notifier_block nb;
147 unsigned long polling_jiffies;
148 unsigned long previous_freq;
149 unsigned int next_polling;
151 void *data; /* private data for governors */
155 unsigned long min_freq;
156 unsigned long max_freq;
159 #if defined(CONFIG_PM_DEVFREQ)
160 extern struct devfreq *devfreq_add_device(struct device *dev,
161 struct devfreq_dev_profile *profile,
162 const struct devfreq_governor *governor,
164 extern int devfreq_remove_device(struct devfreq *devfreq);
166 /* Helper functions for devfreq user device driver with OPP. */
167 extern struct opp *devfreq_recommended_opp(struct device *dev,
168 unsigned long *freq);
169 extern int devfreq_register_opp_notifier(struct device *dev,
170 struct devfreq *devfreq);
171 extern int devfreq_unregister_opp_notifier(struct device *dev,
172 struct devfreq *devfreq);
174 #ifdef CONFIG_DEVFREQ_GOV_POWERSAVE
175 extern const struct devfreq_governor devfreq_powersave;
177 #ifdef CONFIG_DEVFREQ_GOV_PERFORMANCE
178 extern const struct devfreq_governor devfreq_performance;
180 #ifdef CONFIG_DEVFREQ_GOV_USERSPACE
181 extern const struct devfreq_governor devfreq_userspace;
183 #ifdef CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND
184 extern const struct devfreq_governor devfreq_simple_ondemand;
186 * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
187 * and devfreq_add_device
188 * @ upthreshold If the load is over this value, the frequency jumps.
189 * Specify 0 to use the default. Valid value = 0 to 100.
190 * @ downdifferential If the load is under upthreshold - downdifferential,
191 * the governor may consider slowing the frequency down.
192 * Specify 0 to use the default. Valid value = 0 to 100.
193 * downdifferential < upthreshold must hold.
195 * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
196 * the governor uses the default values.
198 struct devfreq_simple_ondemand_data {
199 unsigned int upthreshold;
200 unsigned int downdifferential;
204 #else /* !CONFIG_PM_DEVFREQ */
205 static struct devfreq *devfreq_add_device(struct device *dev,
206 struct devfreq_dev_profile *profile,
207 struct devfreq_governor *governor,
213 static int devfreq_remove_device(struct devfreq *devfreq)
218 static struct opp *devfreq_recommended_opp(struct device *dev,
224 static int devfreq_register_opp_notifier(struct device *dev,
225 struct devfreq *devfreq)
230 static int devfreq_unregister_opp_notifier(struct device *dev,
231 struct devfreq *devfreq)
236 #define devfreq_powersave NULL
237 #define devfreq_performance NULL
238 #define devfreq_userspace NULL
239 #define devfreq_simple_ondemand NULL
241 #endif /* CONFIG_PM_DEVFREQ */
243 #endif /* __LINUX_DEVFREQ_H__ */