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 * @exit An optional callback that is called when devfreq
70 * is removing the devfreq object due to error or
71 * from devfreq_remove_device() call. If the user
72 * has registered devfreq->nb at a notifier-head,
73 * this is the time to unregister it.
75 struct devfreq_dev_profile
{
76 unsigned long initial_freq
;
77 unsigned int polling_ms
;
79 int (*target
)(struct device
*dev
, unsigned long *freq
, u32 flags
);
80 int (*get_dev_status
)(struct device
*dev
,
81 struct devfreq_dev_status
*stat
);
82 void (*exit
)(struct device
*dev
);
86 * struct devfreq_governor - Devfreq policy governor
87 * @name Governor's name
88 * @get_target_freq Returns desired operating frequency for the device.
89 * Basically, get_target_freq will run
90 * devfreq_dev_profile.get_dev_status() to get the
91 * status of the device (load = busy_time / total_time).
92 * If no_central_polling is set, this callback is called
93 * only with update_devfreq() notified by OPP.
94 * @event_handler Callback for devfreq core framework to notify events
95 * to governors. Events include per device governor
96 * init and exit, opp changes out of devfreq, suspend
97 * and resume of per device devfreq during device idle.
99 * Note that the callbacks are called with devfreq->lock locked by devfreq.
101 struct devfreq_governor
{
102 const char name
[DEVFREQ_NAME_LEN
];
103 int (*get_target_freq
)(struct devfreq
*this, unsigned long *freq
);
104 int (*event_handler
)(struct devfreq
*devfreq
,
105 unsigned int event
, void *data
);
109 * struct devfreq - Device devfreq structure
110 * @node list node - contains the devices with devfreq that have been
112 * @lock a mutex to protect accessing devfreq.
113 * @dev device registered by devfreq class. dev.parent is the device
115 * @profile device-specific devfreq profile
116 * @governor method how to choose frequency based on the usage.
117 * @nb notifier block used to notify devfreq object that it should
118 * reevaluate operable frequencies. Devfreq users may use
119 * devfreq.nb to the corresponding register notifier call chain.
120 * @work delayed work for load monitoring.
121 * @previous_freq previously configured frequency value.
122 * @data Private data of the governor. The devfreq framework does not
124 * @min_freq Limit minimum frequency requested by user (0: none)
125 * @max_freq Limit maximum frequency requested by user (0: none)
126 * @stop_polling devfreq polling status of a device.
128 * This structure stores the devfreq information for a give device.
130 * Note that when a governor accesses entries in struct devfreq in its
131 * functions except for the context of callbacks defined in struct
132 * devfreq_governor, the governor should protect its access with the
133 * struct mutex lock in struct devfreq. A governor may use this mutex
134 * to protect its own private data in void *data as well.
137 struct list_head node
;
141 struct devfreq_dev_profile
*profile
;
142 const struct devfreq_governor
*governor
;
143 struct notifier_block nb
;
144 struct delayed_work work
;
146 unsigned long previous_freq
;
148 void *data
; /* private data for governors */
150 unsigned long min_freq
;
151 unsigned long max_freq
;
155 #if defined(CONFIG_PM_DEVFREQ)
156 extern struct devfreq
*devfreq_add_device(struct device
*dev
,
157 struct devfreq_dev_profile
*profile
,
158 const struct devfreq_governor
*governor
,
160 extern int devfreq_remove_device(struct devfreq
*devfreq
);
162 /* Helper functions for devfreq user device driver with OPP. */
163 extern struct opp
*devfreq_recommended_opp(struct device
*dev
,
164 unsigned long *freq
, u32 flags
);
165 extern int devfreq_register_opp_notifier(struct device
*dev
,
166 struct devfreq
*devfreq
);
167 extern int devfreq_unregister_opp_notifier(struct device
*dev
,
168 struct devfreq
*devfreq
);
170 #ifdef CONFIG_DEVFREQ_GOV_POWERSAVE
171 extern const struct devfreq_governor devfreq_powersave
;
173 #ifdef CONFIG_DEVFREQ_GOV_PERFORMANCE
174 extern const struct devfreq_governor devfreq_performance
;
176 #ifdef CONFIG_DEVFREQ_GOV_USERSPACE
177 extern const struct devfreq_governor devfreq_userspace
;
179 #ifdef CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND
180 extern const struct devfreq_governor devfreq_simple_ondemand
;
182 * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
183 * and devfreq_add_device
184 * @ upthreshold If the load is over this value, the frequency jumps.
185 * Specify 0 to use the default. Valid value = 0 to 100.
186 * @ downdifferential If the load is under upthreshold - downdifferential,
187 * the governor may consider slowing the frequency down.
188 * Specify 0 to use the default. Valid value = 0 to 100.
189 * downdifferential < upthreshold must hold.
191 * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
192 * the governor uses the default values.
194 struct devfreq_simple_ondemand_data
{
195 unsigned int upthreshold
;
196 unsigned int downdifferential
;
200 #else /* !CONFIG_PM_DEVFREQ */
201 static struct devfreq
*devfreq_add_device(struct device
*dev
,
202 struct devfreq_dev_profile
*profile
,
203 struct devfreq_governor
*governor
,
209 static int devfreq_remove_device(struct devfreq
*devfreq
)
214 static struct opp
*devfreq_recommended_opp(struct device
*dev
,
215 unsigned long *freq
, u32 flags
)
220 static int devfreq_register_opp_notifier(struct device
*dev
,
221 struct devfreq
*devfreq
)
226 static int devfreq_unregister_opp_notifier(struct device
*dev
,
227 struct devfreq
*devfreq
)
232 #define devfreq_powersave NULL
233 #define devfreq_performance NULL
234 #define devfreq_userspace NULL
235 #define devfreq_simple_ondemand NULL
237 #endif /* CONFIG_PM_DEVFREQ */
239 #endif /* __LINUX_DEVFREQ_H__ */