power.h revision 501fc0f18249468d485415a3a7f892c644271e63 
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
40typedef enum {
41    POWER_HINT_VSYNC = 0x00000001,
42    POWER_HINT_INTERACTION = 0x00000002,
43    POWER_HINT_VIDEO_ENCODE = 0x00000003,
44    POWER_HINT_VIDEO_DECODE = 0x00000004
45} power_hint_t;
46
47/**
48 * Every hardware module must have a data structure named HAL_MODULE_INFO_SYM
49 * and the fields of this data structure must begin with hw_module_t
50 * followed by module specific information.
51 */
52typedef struct power_module {
53    struct hw_module_t common;
54
55    /*
56     * (*init)() performs power management setup actions at runtime
57     * startup, such as to set default cpufreq parameters.  This is
58     * called only by the Power HAL instance loaded by
59     * PowerManagerService.
60     */
61    void (*init)(struct power_module *module);
62
63    /*
64     * (*setInteractive)() performs power management actions upon the
65     * system entering interactive state (that is, the system is awake
66     * and ready for interaction, often with UI devices such as
67     * display and touchscreen enabled) or non-interactive state (the
68     * system appears asleep, display usually turned off).  The
69     * non-interactive state is usually entered after a period of
70     * inactivity, in order to conserve battery power during
71     * such inactive periods.
72     *
73     * Typical actions are to turn on or off devices and adjust
74     * cpufreq parameters.  This function may also call the
75     * appropriate interfaces to allow the kernel to suspend the
76     * system to low-power sleep state when entering non-interactive
77     * state, and to disallow low-power suspend when the system is in
78     * interactive state.  When low-power suspend state is allowed, the
79     * kernel may suspend the system whenever no wakelocks are held.
80     *
81     * on is non-zero when the system is transitioning to an
82     * interactive / awake state, and zero when transitioning to a
83     * non-interactive / asleep state.
84     *
85     * This function is called to enter non-interactive state after
86     * turning off the screen (if present), and called to enter
87     * interactive state prior to turning on the screen.
88     */
89    void (*setInteractive)(struct power_module *module, int on);
90
91    /*
92     * (*powerHint) is called to pass hints on power requirements, which
93     * may result in adjustment of power/performance parameters of the
94     * cpufreq governor and other controls.  The possible hints are:
95     *
96     * POWER_HINT_VSYNC
97     *
98     *     Foreground app has started or stopped requesting a VSYNC pulse
99     *     from SurfaceFlinger.  If the app has started requesting VSYNC
100     *     then CPU and GPU load is expected soon, and it may be appropriate
101     *     to raise speeds of CPU, memory bus, etc.  The data parameter is
102     *     non-zero to indicate VSYNC pulse is now requested, or zero for
103     *     VSYNC pulse no longer requested.
104     *
105     * POWER_HINT_INTERACTION
106     *
107     *     User is interacting with the device, for example, touchscreen
108     *     events are incoming.  CPU and GPU load may be expected soon,
109     *     and it may be appropriate to raise speeds of CPU, memory bus,
110     *     etc.  The data parameter is unused.
111     *
112     * A particular platform may choose to ignore any hint.
113     *
114     * availability: version 0.2
115     *
116     */
117    void (*powerHint)(struct power_module *module, power_hint_t hint,
118                      void *data);
119} power_module_t;
120
121
122__END_DECLS
123
124#endif  // ANDROID_INCLUDE_HARDWARE_POWER_H
125