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 * @name: Governor's name
96 * @get_target_freq: Returns desired operating frequency for the device.
97 * Basically, get_target_freq will run
98 * devfreq_dev_profile.get_dev_status() to get the
99 * status of the device (load = busy_time / total_time).
100 * If no_central_polling is set, this callback is called
101 * only with update_devfreq() notified by OPP.
102 * @event_handler: Callback for devfreq core framework to notify events
103 * to governors. Events include per device governor
104 * init and exit, opp changes out of devfreq, suspend
105 * and resume of per device devfreq during device idle.
107 * Note that the callbacks are called with devfreq->lock locked by devfreq.
109 struct devfreq_governor {
110 const char name[DEVFREQ_NAME_LEN];
111 int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
112 int (*event_handler)(struct devfreq *devfreq,
113 unsigned int event, void *data);
117 * struct devfreq - Device devfreq structure
118 * @node: list node - contains the devices with devfreq that have been
120 * @lock: a mutex to protect accessing devfreq.
121 * @dev: device registered by devfreq class. dev.parent is the device
123 * @profile: device-specific devfreq profile
124 * @governor: method how to choose frequency based on the usage.
125 * @nb: notifier block used to notify devfreq object that it should
126 * reevaluate operable frequencies. Devfreq users may use
127 * devfreq.nb to the corresponding register notifier call chain.
128 * @work: delayed work for load monitoring.
129 * @previous_freq: previously configured frequency value.
130 * @data: Private data of the governor. The devfreq framework does not
132 * @min_freq: Limit minimum frequency requested by user (0: none)
133 * @max_freq: Limit maximum frequency requested by user (0: none)
134 * @stop_polling: devfreq polling status of a device.
135 * @total_trans: Number of devfreq transitions
136 * @trans_table: Statistics of devfreq transitions
137 * @time_in_state: Statistics of devfreq states
138 * @last_stat_updated: The last time stat updated
140 * This structure stores the devfreq information for a give device.
142 * Note that when a governor accesses entries in struct devfreq in its
143 * functions except for the context of callbacks defined in struct
144 * devfreq_governor, the governor should protect its access with the
145 * struct mutex lock in struct devfreq. A governor may use this mutex
146 * to protect its own private data in void *data as well.
149 struct list_head node;
153 struct devfreq_dev_profile *profile;
154 const struct devfreq_governor *governor;
155 struct notifier_block nb;
156 struct delayed_work work;
158 unsigned long previous_freq;
160 void *data; /* private data for governors */
162 unsigned long min_freq;
163 unsigned long max_freq;
166 /* information for device freqeuncy transition */
167 unsigned int total_trans;
168 unsigned int *trans_table;
169 unsigned long *time_in_state;
170 unsigned long last_stat_updated;
173 #if defined(CONFIG_PM_DEVFREQ)
174 extern struct devfreq *devfreq_add_device(struct device *dev,
175 struct devfreq_dev_profile *profile,
176 const struct devfreq_governor *governor,
178 extern int devfreq_remove_device(struct devfreq *devfreq);
179 extern int devfreq_suspend_device(struct devfreq *devfreq);
180 extern int devfreq_resume_device(struct devfreq *devfreq);
182 /* Helper functions for devfreq user device driver with OPP. */
183 extern struct opp *devfreq_recommended_opp(struct device *dev,
184 unsigned long *freq, u32 flags);
185 extern int devfreq_register_opp_notifier(struct device *dev,
186 struct devfreq *devfreq);
187 extern int devfreq_unregister_opp_notifier(struct device *dev,
188 struct devfreq *devfreq);
190 #ifdef CONFIG_DEVFREQ_GOV_POWERSAVE
191 extern const struct devfreq_governor devfreq_powersave;
193 #ifdef CONFIG_DEVFREQ_GOV_PERFORMANCE
194 extern const struct devfreq_governor devfreq_performance;
196 #ifdef CONFIG_DEVFREQ_GOV_USERSPACE
197 extern const struct devfreq_governor devfreq_userspace;
199 #ifdef CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND
200 extern const struct devfreq_governor devfreq_simple_ondemand;
202 * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
203 * and devfreq_add_device
204 * @upthreshold: If the load is over this value, the frequency jumps.
205 * Specify 0 to use the default. Valid value = 0 to 100.
206 * @downdifferential: If the load is under upthreshold - downdifferential,
207 * the governor may consider slowing the frequency down.
208 * Specify 0 to use the default. Valid value = 0 to 100.
209 * downdifferential < upthreshold must hold.
211 * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
212 * the governor uses the default values.
214 struct devfreq_simple_ondemand_data {
215 unsigned int upthreshold;
216 unsigned int downdifferential;
220 #else /* !CONFIG_PM_DEVFREQ */
221 static struct devfreq *devfreq_add_device(struct device *dev,
222 struct devfreq_dev_profile *profile,
223 struct devfreq_governor *governor,
229 static int devfreq_remove_device(struct devfreq *devfreq)
234 static int devfreq_suspend_device(struct devfreq *devfreq)
239 static int devfreq_resume_device(struct devfreq *devfreq)
244 static struct opp *devfreq_recommended_opp(struct device *dev,
245 unsigned long *freq, u32 flags)
250 static int devfreq_register_opp_notifier(struct device *dev,
251 struct devfreq *devfreq)
256 static int devfreq_unregister_opp_notifier(struct device *dev,
257 struct devfreq *devfreq)
262 #define devfreq_powersave NULL
263 #define devfreq_performance NULL
264 #define devfreq_userspace NULL
265 #define devfreq_simple_ondemand NULL
267 #endif /* CONFIG_PM_DEVFREQ */
269 #endif /* __LINUX_DEVFREQ_H__ */