power.h revision 2f143fba74f6be91fe8805ef8bbdffe5b8ece8b4 
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/**
29 * The id of this module
30 */
31#define POWER_HARDWARE_MODULE_ID "power"
32
33/*
34 * Power hint identifiers passed to (*powerHint)
35 */
36
37typedef enum {
38    /*
39     * VSYNC pulse request from SurfaceFlinger started or stopped.
40     */
41    POWER_HINT_VSYNC = 0x00000001,
42} power_hint_t;
43
44/**
45 * Every hardware module must have a data structure named HAL_MODULE_INFO_SYM
46 * and the fields of this data structure must begin with hw_module_t
47 * followed by module specific information.
48 */
49typedef struct power_module {
50    struct hw_module_t common;
51
52    /*
53     * (*init)() performs power management setup actions at runtime
54     * startup, such as to set default cpufreq parameters.  This is
55     * called only by the Power HAL instance loaded by
56     * PowerManagerService.
57     */
58    void (*init)(struct power_module *module);
59
60    /*
61     * (*setInteractive)() performs power management actions upon the
62     * system entering interactive state (that is, the system is awake
63     * and ready for interaction, often with UI devices such as
64     * display and touchscreen enabled) or non-interactive state (the
65     * system appears asleep, display usually turned off).  The
66     * non-interactive state is usually entered after a period of
67     * inactivity, in order to conserve battery power during
68     * such inactive periods.
69     *
70     * Typical actions are to turn on or off devices and adjust
71     * cpufreq parameters.  This function may also call the
72     * appropriate interfaces to allow the kernel to suspend the
73     * system to low-power sleep state when entering non-interactive
74     * state, and to disallow low-power suspend when the system is in
75     * interactive state.  When low-power suspend state is allowed, the
76     * kernel may suspend the system whenever no wakelocks are held.
77     *
78     * on is non-zero when the system is transitioning to an
79     * interactive / awake state, and zero when transitioning to a
80     * non-interactive / asleep state.
81     *
82     * This function is called to enter non-interactive state after
83     * turning off the screen (if present), and called to enter
84     * interactive state prior to turning on the screen.
85     */
86    void (*setInteractive)(struct power_module *module, int on);
87
88    /*
89     * (*powerHint) is called to pass hints on power requirements, which
90     * may result in adjustment of power/performance parameters of the
91     * cpufreq governor and other controls.  The possible hints are:
92     *
93     * POWER_HINT_VSYNC
94     *
95     *     Foreground app has started or stopped requesting a VSYNC pulse
96     *     from SurfaceFlinger.  If the app has started requesting VSYNC
97     *     then CPU and GPU load is expected soon, and it may be appropriate
98     *     to raise speeds of CPU, memory bus, etc.  The data parameter is
99     *     non-zero to indicate VSYNC pulse is now requested, or zero for
100     *     VSYNC pulse no longer requested.
101     *
102     * A particular platform may choose to ignore any hint.
103     */
104    void (*powerHint)(struct power_module *module, power_hint_t hint,
105                      void *data);
106} power_module_t;
107
108
109__END_DECLS
110
111#endif  // ANDROID_INCLUDE_HARDWARE_POWER_H
112