Android Hardware Abstraction Layer
power.h
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1 /*
2  * Copyright (C) 2012 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef ANDROID_INCLUDE_HARDWARE_POWER_H
18 #define ANDROID_INCLUDE_HARDWARE_POWER_H
19 
20 #include <stdint.h>
21 #include <sys/cdefs.h>
22 #include <sys/types.h>
23 
24 #include <hardware/hardware.h>
25 
26 __BEGIN_DECLS
27 
28 #define POWER_MODULE_API_VERSION_0_1 HARDWARE_MODULE_API_VERSION(0, 1)
29 #define POWER_MODULE_API_VERSION_0_2 HARDWARE_MODULE_API_VERSION(0, 2)
30 
31 /**
32  * The id of this module
33  */
34 #define POWER_HARDWARE_MODULE_ID "power"
35 
36 /*
37  * Power hint identifiers passed to (*powerHint)
38  */
39 
40 typedef enum {
41  POWER_HINT_VSYNC = 0x00000001,
42  POWER_HINT_INTERACTION = 0x00000002,
43  /* DO NOT USE POWER_HINT_VIDEO_ENCODE/_DECODE! They will be removed in
44  * KLP.
45  */
48 } power_hint_t;
49 
50 /**
51  * Every hardware module must have a data structure named HAL_MODULE_INFO_SYM
52  * and the fields of this data structure must begin with hw_module_t
53  * followed by module specific information.
54  */
55 typedef struct power_module {
57 
58  /*
59  * (*init)() performs power management setup actions at runtime
60  * startup, such as to set default cpufreq parameters. This is
61  * called only by the Power HAL instance loaded by
62  * PowerManagerService.
63  */
64  void (*init)(struct power_module *module);
65 
66  /*
67  * (*setInteractive)() performs power management actions upon the
68  * system entering interactive state (that is, the system is awake
69  * and ready for interaction, often with UI devices such as
70  * display and touchscreen enabled) or non-interactive state (the
71  * system appears asleep, display usually turned off). The
72  * non-interactive state is usually entered after a period of
73  * inactivity, in order to conserve battery power during
74  * such inactive periods.
75  *
76  * Typical actions are to turn on or off devices and adjust
77  * cpufreq parameters. This function may also call the
78  * appropriate interfaces to allow the kernel to suspend the
79  * system to low-power sleep state when entering non-interactive
80  * state, and to disallow low-power suspend when the system is in
81  * interactive state. When low-power suspend state is allowed, the
82  * kernel may suspend the system whenever no wakelocks are held.
83  *
84  * on is non-zero when the system is transitioning to an
85  * interactive / awake state, and zero when transitioning to a
86  * non-interactive / asleep state.
87  *
88  * This function is called to enter non-interactive state after
89  * turning off the screen (if present), and called to enter
90  * interactive state prior to turning on the screen.
91  */
92  void (*setInteractive)(struct power_module *module, int on);
93 
94  /*
95  * (*powerHint) is called to pass hints on power requirements, which
96  * may result in adjustment of power/performance parameters of the
97  * cpufreq governor and other controls. The possible hints are:
98  *
99  * POWER_HINT_VSYNC
100  *
101  * Foreground app has started or stopped requesting a VSYNC pulse
102  * from SurfaceFlinger. If the app has started requesting VSYNC
103  * then CPU and GPU load is expected soon, and it may be appropriate
104  * to raise speeds of CPU, memory bus, etc. The data parameter is
105  * non-zero to indicate VSYNC pulse is now requested, or zero for
106  * VSYNC pulse no longer requested.
107  *
108  * POWER_HINT_INTERACTION
109  *
110  * User is interacting with the device, for example, touchscreen
111  * events are incoming. CPU and GPU load may be expected soon,
112  * and it may be appropriate to raise speeds of CPU, memory bus,
113  * etc. The data parameter is unused.
114  *
115  * A particular platform may choose to ignore any hint.
116  *
117  * availability: version 0.2
118  *
119  */
120  void (*powerHint)(struct power_module *module, power_hint_t hint,
121  void *data);
123 
124 
125 __END_DECLS
126 
127 #endif // ANDROID_INCLUDE_HARDWARE_POWER_H