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 * The resulting frequency should be at most this. (this bound is the
49 * least upper bound; thus, the resulting freq should be lower or same)
50 * If the flag is not set, the resulting frequency should be at most the
51 * bound (greatest lower bound)
53 #define DEVFREQ_FLAG_LEAST_UPPER_BOUND 0x1
56 * struct devfreq_dev_profile - Devfreq's user device profile
57 * @initial_freq: The operating frequency when devfreq_add_device() is
59 * @polling_ms: The polling interval in ms. 0 disables polling.
60 * @target: The device should set its operating frequency at
61 * freq or lowest-upper-than-freq value. If freq is
62 * higher than any operable frequency, set maximum.
63 * Before returning, target function should set
64 * freq at the current frequency.
65 * The "flags" parameter's possible values are
66 * explained above with "DEVFREQ_FLAG_*" macros.
67 * @get_dev_status: The device should provide the current performance
68 * status to devfreq, which is used by governors.
69 * @get_cur_freq: The device should provide the current frequency
70 * at which it is operating.
71 * @exit: An optional callback that is called when devfreq
72 * is removing the devfreq object due to error or
73 * from devfreq_remove_device() call. If the user
74 * has registered devfreq->nb at a notifier-head,
75 * this is the time to unregister it.
76 * @freq_table: Optional list of frequencies to support statistics.
77 * @max_state: The size of freq_table.
79 struct devfreq_dev_profile
{
80 unsigned long initial_freq
;
81 unsigned int polling_ms
;
83 int (*target
)(struct device
*dev
, unsigned long *freq
, u32 flags
);
84 int (*get_dev_status
)(struct device
*dev
,
85 struct devfreq_dev_status
*stat
);
86 int (*get_cur_freq
)(struct device
*dev
, unsigned long *freq
);
87 void (*exit
)(struct device
*dev
);
89 unsigned int *freq_table
;
90 unsigned int max_state
;
94 * struct devfreq_governor - Devfreq policy governor
95 * @node: list node - contains registered devfreq governors
96 * @name: Governor's name
97 * @get_target_freq: Returns desired operating frequency for the device.
98 * Basically, get_target_freq will run
99 * devfreq_dev_profile.get_dev_status() to get the
100 * status of the device (load = busy_time / total_time).
101 * If no_central_polling is set, this callback is called
102 * only with update_devfreq() notified by OPP.
103 * @event_handler: Callback for devfreq core framework to notify events
104 * to governors. Events include per device governor
105 * init and exit, opp changes out of devfreq, suspend
106 * and resume of per device devfreq during device idle.
108 * Note that the callbacks are called with devfreq->lock locked by devfreq.
110 struct devfreq_governor
{
111 struct list_head node
;
113 const char name
[DEVFREQ_NAME_LEN
];
114 int (*get_target_freq
)(struct devfreq
*this, unsigned long *freq
);
115 int (*event_handler
)(struct devfreq
*devfreq
,
116 unsigned int event
, void *data
);
120 * struct devfreq - Device devfreq structure
121 * @node: list node - contains the devices with devfreq that have been
123 * @lock: a mutex to protect accessing devfreq.
124 * @dev: device registered by devfreq class. dev.parent is the device
126 * @profile: device-specific devfreq profile
127 * @governor: method how to choose frequency based on the usage.
128 * @governor_name: devfreq governor name for use with this devfreq
129 * @nb: notifier block used to notify devfreq object that it should
130 * reevaluate operable frequencies. Devfreq users may use
131 * devfreq.nb to the corresponding register notifier call chain.
132 * @work: delayed work for load monitoring.
133 * @previous_freq: previously configured frequency value.
134 * @data: Private data of the governor. The devfreq framework does not
136 * @min_freq: Limit minimum frequency requested by user (0: none)
137 * @max_freq: Limit maximum frequency requested by user (0: none)
138 * @stop_polling: devfreq polling status of a device.
139 * @total_trans: Number of devfreq transitions
140 * @trans_table: Statistics of devfreq transitions
141 * @time_in_state: Statistics of devfreq states
142 * @last_stat_updated: The last time stat updated
144 * This structure stores the devfreq information for a give device.
146 * Note that when a governor accesses entries in struct devfreq in its
147 * functions except for the context of callbacks defined in struct
148 * devfreq_governor, the governor should protect its access with the
149 * struct mutex lock in struct devfreq. A governor may use this mutex
150 * to protect its own private data in void *data as well.
153 struct list_head node
;
157 struct devfreq_dev_profile
*profile
;
158 const struct devfreq_governor
*governor
;
159 char governor_name
[DEVFREQ_NAME_LEN
];
160 struct notifier_block nb
;
161 struct delayed_work work
;
163 unsigned long previous_freq
;
165 void *data
; /* private data for governors */
167 unsigned long min_freq
;
168 unsigned long max_freq
;
171 /* information for device freqeuncy transition */
172 unsigned int total_trans
;
173 unsigned int *trans_table
;
174 unsigned long *time_in_state
;
175 unsigned long last_stat_updated
;
178 #if defined(CONFIG_PM_DEVFREQ)
179 extern struct devfreq
*devfreq_add_device(struct device
*dev
,
180 struct devfreq_dev_profile
*profile
,
181 const char *governor_name
,
183 extern int devfreq_remove_device(struct devfreq
*devfreq
);
185 /* Supposed to be called by PM_SLEEP/PM_RUNTIME callbacks */
186 extern int devfreq_suspend_device(struct devfreq
*devfreq
);
187 extern int devfreq_resume_device(struct devfreq
*devfreq
);
189 /* Helper functions for devfreq user device driver with OPP. */
190 extern struct dev_pm_opp
*devfreq_recommended_opp(struct device
*dev
,
191 unsigned long *freq
, u32 flags
);
192 extern int devfreq_register_opp_notifier(struct device
*dev
,
193 struct devfreq
*devfreq
);
194 extern int devfreq_unregister_opp_notifier(struct device
*dev
,
195 struct devfreq
*devfreq
);
197 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
199 * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
200 * and devfreq_add_device
201 * @upthreshold: If the load is over this value, the frequency jumps.
202 * Specify 0 to use the default. Valid value = 0 to 100.
203 * @downdifferential: If the load is under upthreshold - downdifferential,
204 * the governor may consider slowing the frequency down.
205 * Specify 0 to use the default. Valid value = 0 to 100.
206 * downdifferential < upthreshold must hold.
208 * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
209 * the governor uses the default values.
211 struct devfreq_simple_ondemand_data
{
212 unsigned int upthreshold
;
213 unsigned int downdifferential
;
217 #else /* !CONFIG_PM_DEVFREQ */
218 static inline struct devfreq
*devfreq_add_device(struct device
*dev
,
219 struct devfreq_dev_profile
*profile
,
220 const char *governor_name
,
226 static inline int devfreq_remove_device(struct devfreq
*devfreq
)
231 static inline int devfreq_suspend_device(struct devfreq
*devfreq
)
236 static inline int devfreq_resume_device(struct devfreq
*devfreq
)
241 static inline struct dev_pm_opp
*devfreq_recommended_opp(struct device
*dev
,
242 unsigned long *freq
, u32 flags
)
244 return ERR_PTR(-EINVAL
);
247 static inline int devfreq_register_opp_notifier(struct device
*dev
,
248 struct devfreq
*devfreq
)
253 static inline int devfreq_unregister_opp_notifier(struct device
*dev
,
254 struct devfreq
*devfreq
)
259 #endif /* CONFIG_PM_DEVFREQ */
261 #endif /* __LINUX_DEVFREQ_H__ */