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
22 struct 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 */
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;
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 * @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.
74 */
75 struct devfreq_dev_profile {
76 unsigned long initial_freq;
77 unsigned int polling_ms;
78
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);
83 };
84
85 /**
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 * @init Called when the devfreq is being attached to a device
95 * @exit Called when the devfreq is being removed from a
96 * device. Governor should stop any internal routines
97 * before return because related data may be
98 * freed after exit().
99 * @no_central_polling Do not use devfreq's central polling mechanism.
100 * When this is set, devfreq will not call
101 * get_target_freq with devfreq_monitor(). However,
102 * devfreq will call get_target_freq with
103 * devfreq_update() notified by OPP framework.
104 *
105 * Note that the callbacks are called with devfreq->lock locked by devfreq.
106 */
107 struct devfreq_governor {
108 const char name[DEVFREQ_NAME_LEN];
109 int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
110 int (*init)(struct devfreq *this);
111 void (*exit)(struct devfreq *this);
112 const bool no_central_polling;
113 };
114
115 /**
116 * struct devfreq - Device devfreq structure
117 * @node list node - contains the devices with devfreq that have been
118 * registered.
119 * @lock a mutex to protect accessing devfreq.
120 * @dev device registered by devfreq class. dev.parent is the device
121 * using devfreq.
122 * @profile device-specific devfreq profile
123 * @governor method how to choose frequency based on the usage.
124 * @nb notifier block used to notify devfreq object that it should
125 * reevaluate operable frequencies. Devfreq users may use
126 * devfreq.nb to the corresponding register notifier call chain.
127 * @polling_jiffies interval in jiffies.
128 * @previous_freq previously configured frequency value.
129 * @next_polling the number of remaining jiffies to poll with
130 * "devfreq_monitor" executions to reevaluate
131 * frequency/voltage of the device. Set by
132 * profile's polling_ms interval.
133 * @data Private data of the governor. The devfreq framework does not
134 * touch this.
135 * @being_removed a flag to mark that this object is being removed in
136 * order to prevent trying to remove the object multiple times.
137 * @min_freq Limit minimum frequency requested by user (0: none)
138 * @max_freq Limit maximum frequency requested by user (0: none)
139 *
140 * This structure stores the devfreq information for a give device.
141 *
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.
147 */
148 struct devfreq {
149 struct list_head node;
150
151 struct mutex lock;
152 struct device dev;
153 struct devfreq_dev_profile *profile;
154 const struct devfreq_governor *governor;
155 struct notifier_block nb;
156
157 unsigned long polling_jiffies;
158 unsigned long previous_freq;
159 unsigned int next_polling;
160
161 void *data; /* private data for governors */
162
163 bool being_removed;
164
165 unsigned long min_freq;
166 unsigned long max_freq;
167 };
168
169 #if defined(CONFIG_PM_DEVFREQ)
170 extern struct devfreq *devfreq_add_device(struct device *dev,
171 struct devfreq_dev_profile *profile,
172 const struct devfreq_governor *governor,
173 void *data);
174 extern int devfreq_remove_device(struct devfreq *devfreq);
175
176 /* Helper functions for devfreq user device driver with OPP. */
177 extern struct opp *devfreq_recommended_opp(struct device *dev,
178 unsigned long *freq, u32 flags);
179 extern int devfreq_register_opp_notifier(struct device *dev,
180 struct devfreq *devfreq);
181 extern int devfreq_unregister_opp_notifier(struct device *dev,
182 struct devfreq *devfreq);
183
184 #ifdef CONFIG_DEVFREQ_GOV_POWERSAVE
185 extern const struct devfreq_governor devfreq_powersave;
186 #endif
187 #ifdef CONFIG_DEVFREQ_GOV_PERFORMANCE
188 extern const struct devfreq_governor devfreq_performance;
189 #endif
190 #ifdef CONFIG_DEVFREQ_GOV_USERSPACE
191 extern const struct devfreq_governor devfreq_userspace;
192 #endif
193 #ifdef CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND
194 extern const struct devfreq_governor devfreq_simple_ondemand;
195 /**
196 * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
197 * and devfreq_add_device
198 * @ upthreshold If the load is over this value, the frequency jumps.
199 * Specify 0 to use the default. Valid value = 0 to 100.
200 * @ downdifferential If the load is under upthreshold - downdifferential,
201 * the governor may consider slowing the frequency down.
202 * Specify 0 to use the default. Valid value = 0 to 100.
203 * downdifferential < upthreshold must hold.
204 *
205 * If the fed devfreq_simple_ondemand_data pointer is NULL to the governor,
206 * the governor uses the default values.
207 */
208 struct devfreq_simple_ondemand_data {
209 unsigned int upthreshold;
210 unsigned int downdifferential;
211 };
212 #endif
213
214 #else /* !CONFIG_PM_DEVFREQ */
devfreq_add_device(struct device * dev,struct devfreq_dev_profile * profile,struct devfreq_governor * governor,void * data)215 static struct devfreq *devfreq_add_device(struct device *dev,
216 struct devfreq_dev_profile *profile,
217 struct devfreq_governor *governor,
218 void *data)
219 {
220 return NULL;
221 }
222
devfreq_remove_device(struct devfreq * devfreq)223 static int devfreq_remove_device(struct devfreq *devfreq)
224 {
225 return 0;
226 }
227
devfreq_recommended_opp(struct device * dev,unsigned long * freq,u32 flags)228 static struct opp *devfreq_recommended_opp(struct device *dev,
229 unsigned long *freq, u32 flags)
230 {
231 return -EINVAL;
232 }
233
devfreq_register_opp_notifier(struct device * dev,struct devfreq * devfreq)234 static int devfreq_register_opp_notifier(struct device *dev,
235 struct devfreq *devfreq)
236 {
237 return -EINVAL;
238 }
239
devfreq_unregister_opp_notifier(struct device * dev,struct devfreq * devfreq)240 static int devfreq_unregister_opp_notifier(struct device *dev,
241 struct devfreq *devfreq)
242 {
243 return -EINVAL;
244 }
245
246 #define devfreq_powersave NULL
247 #define devfreq_performance NULL
248 #define devfreq_userspace NULL
249 #define devfreq_simple_ondemand NULL
250
251 #endif /* CONFIG_PM_DEVFREQ */
252
253 #endif /* __LINUX_DEVFREQ_H__ */
254