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diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
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1/*
2 * devfreq: Generic Dynamic Voltage and Frequency Scaling (DVFS) Framework
3 * for Non-CPU Devices.
4 *
5 * Copyright (C) 2011 Samsung Electronics
6 * MyungJoo Ham <myungjoo.ham@samsung.com>
7 *
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.
11 */
12
13#ifndef __LINUX_DEVFREQ_H__
14#define __LINUX_DEVFREQ_H__
15
16#include <linux/device.h>
17#include <linux/notifier.h>
18#include <linux/opp.h>
19
20#define DEVFREQ_NAME_LEN 16
21
22struct devfreq;
23
24/**
25 * struct devfreq_dev_status - Data given from devfreq user device to
26 * governors. Represents the performance
27 * statistics.
28 * @total_time: The total time represented by this instance of
29 * devfreq_dev_status
30 * @busy_time: The time that the device was working among the
31 * total_time.
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.
38 */
39struct devfreq_dev_status {
40 /* both since the last measure */
41 unsigned long total_time;
42 unsigned long busy_time;
43 unsigned long current_frequency;
44 void *private_data;
45};
46
47/*
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)
52 */
53#define DEVFREQ_FLAG_LEAST_UPPER_BOUND 0x1
54
55/**
56 * struct devfreq_dev_profile - Devfreq's user device profile
57 * @initial_freq: The operating frequency when devfreq_add_device() is
58 * called.
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.
78 */
79struct devfreq_dev_profile {
80 unsigned long initial_freq;
81 unsigned int polling_ms;
82
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);
88
89 unsigned int *freq_table;
90 unsigned int max_state;
91};
92
93/**
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.
107 *
108 * Note that the callbacks are called with devfreq->lock locked by devfreq.
109 */
110struct devfreq_governor {
111 struct list_head node;
112
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);
117};
118
119/**
120 * struct devfreq - Device devfreq structure
121 * @node: list node - contains the devices with devfreq that have been
122 * registered.
123 * @lock: a mutex to protect accessing devfreq.
124 * @dev: device registered by devfreq class. dev.parent is the device
125 * using devfreq.
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
135 * touch this.
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
143 *
144 * This structure stores the devfreq information for a give device.
145 *
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.
151 */
152struct devfreq {
153 struct list_head node;
154
155 struct mutex lock;
156 struct device dev;
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;
162
163 unsigned long previous_freq;
164
165 void *data; /* private data for governors */
166
167 unsigned long min_freq;
168 unsigned long max_freq;
169 bool stop_polling;
170
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;
176};
177
178#if defined(CONFIG_PM_DEVFREQ)
179extern struct devfreq *devfreq_add_device(struct device *dev,
180 struct devfreq_dev_profile *profile,
181 const char *governor_name,
182 void *data);
183extern int devfreq_remove_device(struct devfreq *devfreq);
184extern int devfreq_suspend_device(struct devfreq *devfreq);
185extern int devfreq_resume_device(struct devfreq *devfreq);
186
187/* Helper functions for devfreq user device driver with OPP. */
188extern struct opp *devfreq_recommended_opp(struct device *dev,
189 unsigned long *freq, u32 flags);
190extern int devfreq_register_opp_notifier(struct device *dev,
191 struct devfreq *devfreq);
192extern int devfreq_unregister_opp_notifier(struct device *dev,
193 struct devfreq *devfreq);
194
195#if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)
196/**
197 * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
198 * and devfreq_add_device
199 * @upthreshold: If the load is over this value, the frequency jumps.
200 * Specify 0 to use the default. Valid value = 0 to 100.
201 * @downdifferential: If the load is under upthreshold - downdifferential,
202 * the governor may consider slowing the frequency down.
203 * Specify 0 to use the default. Valid value = 0 to 100.
204 * downdifferential < upthreshold must hold.
205 *
206 * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
207 * the governor uses the default values.
208 */
209struct devfreq_simple_ondemand_data {
210 unsigned int upthreshold;
211 unsigned int downdifferential;
212};
213#endif
214
215#else /* !CONFIG_PM_DEVFREQ */
216static struct devfreq *devfreq_add_device(struct device *dev,
217 struct devfreq_dev_profile *profile,
218 const char *governor_name,
219 void *data)
220{
221 return NULL;
222}
223
224static int devfreq_remove_device(struct devfreq *devfreq)
225{
226 return 0;
227}
228
229static int devfreq_suspend_device(struct devfreq *devfreq)
230{
231 return 0;
232}
233
234static int devfreq_resume_device(struct devfreq *devfreq)
235{
236 return 0;
237}
238
239static struct opp *devfreq_recommended_opp(struct device *dev,
240 unsigned long *freq, u32 flags)
241{
242 return -EINVAL;
243}
244
245static int devfreq_register_opp_notifier(struct device *dev,
246 struct devfreq *devfreq)
247{
248 return -EINVAL;
249}
250
251static int devfreq_unregister_opp_notifier(struct device *dev,
252 struct devfreq *devfreq)
253{
254 return -EINVAL;
255}
256
257#endif /* CONFIG_PM_DEVFREQ */
258
259#endif /* __LINUX_DEVFREQ_H__ */
generated by cgit v1.2.2 (git 2.25.0) at 2026-05-13 02:03:47 -0400