hardware/power.h

   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
  41 typedef enum {
  42     POWER_HINT_VSYNC = 0x00000001,
  43     POWER_HINT_INTERACTION = 0x00000002,
  44     POWER_HINT_VIDEO_ENCODE = 0x00000003,
  45     POWER_HINT_CPU_BOOST = 0x00000004,
  46 } power_hint_t;
  47
  48 /**
  49  * Every hardware module must have a data structure named HAL_MODULE_INFO_SYM
  50  * and the fields of this data structure must begin with hw_module_t
  51  * followed by module specific information.
  52  */
  53 typedef struct power_module {
  54     struct hw_module_t common;
  55
  56     /*
  57      * (*init)() performs power management setup actions at runtime
  58      * startup, such as to set default cpufreq parameters.  This is
  59      * called only by the Power HAL instance loaded by
  60      * PowerManagerService.
  61      */
  62     void (*init)(struct power_module *module);
  63
  64     /*
  65      * (*setInteractive)() performs power management actions upon the
  66      * system entering interactive state (that is, the system is awake
  67      * and ready for interaction, often with UI devices such as
  68      * display and touchscreen enabled) or non-interactive state (the
  69      * system appears asleep, display usually turned off).  The
  70      * non-interactive state is usually entered after a period of
  71      * inactivity, in order to conserve battery power during
  72      * such inactive periods.
  73      *
  74      * Typical actions are to turn on or off devices and adjust
  75      * cpufreq parameters.  This function may also call the
  76      * appropriate interfaces to allow the kernel to suspend the
  77      * system to low-power sleep state when entering non-interactive
  78      * state, and to disallow low-power suspend when the system is in
  79      * interactive state.  When low-power suspend state is allowed, the
  80      * kernel may suspend the system whenever no wakelocks are held.
  81      *
  82      * on is non-zero when the system is transitioning to an
  83      * interactive / awake state, and zero when transitioning to a
  84      * non-interactive / asleep state.
  85      *
  86      * This function is called to enter non-interactive state after
  87      * turning off the screen (if present), and called to enter
  88      * interactive state prior to turning on the screen.
  89      */
  90     void (*setInteractive)(struct power_module *module, int on);
  91
  92     /*
  93      * (*powerHint) is called to pass hints on power requirements, which
  94      * may result in adjustment of power/performance parameters of the
  95      * cpufreq governor and other controls.  The possible hints are:
  96      *
  97      * POWER_HINT_VSYNC
  98      *
  99      *     Foreground app has started or stopped requesting a VSYNC pulse
 100      *     from SurfaceFlinger.  If the app has started requesting VSYNC
 101      *     then CPU and GPU load is expected soon, and it may be appropriate
 102      *     to raise speeds of CPU, memory bus, etc.  The data parameter is
 103      *     non-zero to indicate VSYNC pulse is now requested, or zero for
 104      *     VSYNC pulse no longer requested.
 105      *
 106      * POWER_HINT_INTERACTION
 107      *
 108      *     User is interacting with the device, for example, touchscreen
 109      *     events are incoming.  CPU and GPU load may be expected soon,
 110      *     and it may be appropriate to raise speeds of CPU, memory bus,
 111      *     etc.  The data parameter is unused.
 112      *
 113      * POWER_HINT_VIDEO_ENCODE
 114      *
 115      *     The user just started or stopped recording video. When encode
 116      *     begins, large writes to the SD card will be done and this may
 117      *     cause CPU frequency to increase. The data parameter is a string
 118      *     with semicolon-separated 'key:value' pairs. The most common key is
 119      *     'state', which takes 0 or 1 as its value. For instance, To
 120      *     indicate that recording is beginning, the string "state:1" would
 121      *     need to be used. More keys can be provided depending on the data
 122      *     that is to be passed.
 123      *
 124      * POWER_HINT_CPU_BOOST
 125      *
 126      *     An operation is happening where it would be ideal for the CPU to
 127      *     be boosted for a specific duration. The data parameter is an
 128      *     integer value of the boost duration in microseconds.
 129      *
 130      * A particular platform may choose to ignore any hint.
 131      *
 132      * availability: version 0.2
 133      *
 134      */
 135     void (*powerHint)(struct power_module *module, power_hint_t hint,
 136                       void *data);
 137 } power_module_t;
 138
 139
 140 __END_DECLS
 141
 142 #endif  // ANDROID_INCLUDE_HARDWARE_POWER_H