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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_date;
45};
46
47/**
48 * struct devfreq_dev_profile - Devfreq's user device profile
49 * @initial_freq The operating frequency when devfreq_add_device() is
50 * called.
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.
64 */
65struct devfreq_dev_profile {
66 unsigned long initial_freq;
67 unsigned int polling_ms;
68
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);
73};
74
75/**
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
88 * freed after exit().
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.
94 *
95 * Note that the callbacks are called with devfreq->lock locked by devfreq.
96 */
97struct 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;
103};
104
105/**
106 * struct devfreq - Device devfreq structure
107 * @node list node - contains the devices with devfreq that have been
108 * registered.
109 * @lock a mutex to protect accessing devfreq.
110 * @dev device registered by devfreq class. dev.parent is the device
111 * using devfreq.
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
124 * touch this.
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 *
128 * This structure stores the devfreq information for a give device.
129 *
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.
135 */
136struct devfreq {
137 struct list_head node;
138
139 struct mutex lock;
140 struct device dev;
141 struct devfreq_dev_profile *profile;
142 const struct devfreq_governor *governor;
143 struct notifier_block nb;
144
145 unsigned long polling_jiffies;
146 unsigned long previous_freq;
147 unsigned int next_polling;
148
149 void *data; /* private data for governors */
150
151 bool being_removed;
152};
153
154#if defined(CONFIG_PM_DEVFREQ)
155extern struct devfreq *devfreq_add_device(struct device *dev,
156 struct devfreq_dev_profile *profile,
157 const struct devfreq_governor *governor,
158 void *data);
159extern int devfreq_remove_device(struct devfreq *devfreq);
160
161/* Helper functions for devfreq user device driver with OPP. */
162extern struct opp *devfreq_recommended_opp(struct device *dev,
163 unsigned long *freq);
164extern int devfreq_register_opp_notifier(struct device *dev,
165 struct devfreq *devfreq);
166extern int devfreq_unregister_opp_notifier(struct device *dev,
167 struct devfreq *devfreq);
168
169#ifdef CONFIG_DEVFREQ_GOV_POWERSAVE
170extern const struct devfreq_governor devfreq_powersave;
171#endif
172#ifdef CONFIG_DEVFREQ_GOV_PERFORMANCE
173extern const struct devfreq_governor devfreq_performance;
174#endif
175#ifdef CONFIG_DEVFREQ_GOV_USERSPACE
176extern const struct devfreq_governor devfreq_userspace;
177#endif
178#ifdef CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND
179extern const struct devfreq_governor devfreq_simple_ondemand;
180/**
181 * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
182 * and devfreq_add_device
183 * @ upthreshold If the load is over this value, the frequency jumps.
184 * Specify 0 to use the default. Valid value = 0 to 100.
185 * @ downdifferential If the load is under upthreshold - downdifferential,
186 * the governor may consider slowing the frequency down.
187 * Specify 0 to use the default. Valid value = 0 to 100.
188 * downdifferential < upthreshold must hold.
189 *
190 * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
191 * the governor uses the default values.
192 */
193struct devfreq_simple_ondemand_data {
194 unsigned int upthreshold;
195 unsigned int downdifferential;
196};
197#endif
198
199#else /* !CONFIG_PM_DEVFREQ */
200static struct devfreq *devfreq_add_device(struct device *dev,
201 struct devfreq_dev_profile *profile,
202 struct devfreq_governor *governor,
203 void *data);
204{
205 return NULL;
206}
207
208static int devfreq_remove_device(struct devfreq *devfreq);
209{
210 return 0;
211}
212
213static struct opp *devfreq_recommended_opp(struct device *dev,
214 unsigned long *freq)
215{
216 return -EINVAL;
217}
218
219static int devfreq_register_opp_notifier(struct device *dev,
220 struct devfreq *devfreq)
221{
222 return -EINVAL;
223}
224
225static int devfreq_unregister_opp_notifier(struct device *dev,
226 struct devfreq *devfreq)
227{
228 return -EINVAL;
229}
230
231#define devfreq_powersave NULL
232#define devfreq_performance NULL
233#define devfreq_userspace NULL
234#define devfreq_simple_ondemand NULL
235
236#endif /* CONFIG_PM_DEVFREQ */
237
238#endif /* __LINUX_DEVFREQ_H__ */
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