power.h revision bcdb4cd34b9c2a4a3ccebf0048137892e5586fe8 
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/**
33 * The id of this module
34 */
35#define POWER_HARDWARE_MODULE_ID "power"
36
37/*
38 * Power hint identifiers passed to (*powerHint)
39 */
40
41typedef enum {
42    POWER_HINT_VSYNC = 0x00000001,
43    POWER_HINT_INTERACTION = 0x00000002,
44} power_hint_t;
45
46/**
47 * Every hardware module must have a data structure named HAL_MODULE_INFO_SYM
48 * and the fields of this data structure must begin with hw_module_t
49 * followed by module specific information.
50 */
51typedef struct power_module {
52    struct hw_module_t common;
53
54    /*
55     * (*init)() performs power management setup actions at runtime
56     * startup, such as to set default cpufreq parameters.  This is
57     * called only by the Power HAL instance loaded by
58     * PowerManagerService.
59     */
60    void (*init)(struct power_module *module);
61
62    /*
63     * (*setInteractive)() performs power management actions upon the
64     * system entering interactive state (that is, the system is awake
65     * and ready for interaction, often with UI devices such as
66     * display and touchscreen enabled) or non-interactive state (the
67     * system appears asleep, display usually turned off).  The
68     * non-interactive state is usually entered after a period of
69     * inactivity, in order to conserve battery power during
70     * such inactive periods.
71     *
72     * Typical actions are to turn on or off devices and adjust
73     * cpufreq parameters.  This function may also call the
74     * appropriate interfaces to allow the kernel to suspend the
75     * system to low-power sleep state when entering non-interactive
76     * state, and to disallow low-power suspend when the system is in
77     * interactive state.  When low-power suspend state is allowed, the
78     * kernel may suspend the system whenever no wakelocks are held.
79     *
80     * on is non-zero when the system is transitioning to an
81     * interactive / awake state, and zero when transitioning to a
82     * non-interactive / asleep state.
83     *
84     * This function is called to enter non-interactive state after
85     * turning off the screen (if present), and called to enter
86     * interactive state prior to turning on the screen.
87     */
88    void (*setInteractive)(struct power_module *module, int on);
89
90    /*
91     * (*powerHint) is called to pass hints on power requirements, which
92     * may result in adjustment of power/performance parameters of the
93     * cpufreq governor and other controls.  The possible hints are:
94     *
95     * POWER_HINT_VSYNC
96     *
97     *     Foreground app has started or stopped requesting a VSYNC pulse
98     *     from SurfaceFlinger.  If the app has started requesting VSYNC
99     *     then CPU and GPU load is expected soon, and it may be appropriate
100     *     to raise speeds of CPU, memory bus, etc.  The data parameter is
101     *     non-zero to indicate VSYNC pulse is now requested, or zero for
102     *     VSYNC pulse no longer requested.
103     *
104     * POWER_HINT_INTERACTION
105     *
106     *     User is interacting with the device, for example, touchscreen
107     *     events are incoming.  CPU and GPU load may be expected soon,
108     *     and it may be appropriate to raise speeds of CPU, memory bus,
109     *     etc.  The data parameter is unused.
110     *
111     * A particular platform may choose to ignore any hint.
112     *
113     * availability: version 0.2
114     *
115     */
116    void (*powerHint)(struct power_module *module, power_hint_t hint,
117                      void *data);
118} power_module_t;
119
120
121__END_DECLS
122
123#endif  // ANDROID_INCLUDE_HARDWARE_POWER_H
124