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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      */
     46     POWER_HINT_VIDEO_ENCODE = 0x00000003,
     47     POWER_HINT_VIDEO_DECODE = 0x00000004,
     48     POWER_HINT_LOW_POWER = 0x00000005
     49 } power_hint_t;
     50 
     51 /**
     52  * Every hardware module must have a data structure named HAL_MODULE_INFO_SYM
     53  * and the fields of this data structure must begin with hw_module_t
     54  * followed by module specific information.
     55  */
     56 typedef struct power_module {
     57     struct hw_module_t common;
     58 
     59     /*
     60      * (*init)() performs power management setup actions at runtime
     61      * startup, such as to set default cpufreq parameters.  This is
     62      * called only by the Power HAL instance loaded by
     63      * PowerManagerService.
     64      */
     65     void (*init)(struct power_module *module);
     66 
     67     /*
     68      * (*setInteractive)() performs power management actions upon the
     69      * system entering interactive state (that is, the system is awake
     70      * and ready for interaction, often with UI devices such as
     71      * display and touchscreen enabled) or non-interactive state (the
     72      * system appears asleep, display usually turned off).  The
     73      * non-interactive state is usually entered after a period of
     74      * inactivity, in order to conserve battery power during
     75      * such inactive periods.
     76      *
     77      * Typical actions are to turn on or off devices and adjust
     78      * cpufreq parameters.  This function may also call the
     79      * appropriate interfaces to allow the kernel to suspend the
     80      * system to low-power sleep state when entering non-interactive
     81      * state, and to disallow low-power suspend when the system is in
     82      * interactive state.  When low-power suspend state is allowed, the
     83      * kernel may suspend the system whenever no wakelocks are held.
     84      *
     85      * on is non-zero when the system is transitioning to an
     86      * interactive / awake state, and zero when transitioning to a
     87      * non-interactive / asleep state.
     88      *
     89      * This function is called to enter non-interactive state after
     90      * turning off the screen (if present), and called to enter
     91      * interactive state prior to turning on the screen.
     92      */
     93     void (*setInteractive)(struct power_module *module, int on);
     94 
     95     /*
     96      * (*powerHint) is called to pass hints on power requirements, which
     97      * may result in adjustment of power/performance parameters of the
     98      * cpufreq governor and other controls.  The possible hints are:
     99      *
    100      * POWER_HINT_VSYNC
    101      *
    102      *     Foreground app has started or stopped requesting a VSYNC pulse
    103      *     from SurfaceFlinger.  If the app has started requesting VSYNC
    104      *     then CPU and GPU load is expected soon, and it may be appropriate
    105      *     to raise speeds of CPU, memory bus, etc.  The data parameter is
    106      *     non-zero to indicate VSYNC pulse is now requested, or zero for
    107      *     VSYNC pulse no longer requested.
    108      *
    109      * POWER_HINT_INTERACTION
    110      *
    111      *     User is interacting with the device, for example, touchscreen
    112      *     events are incoming.  CPU and GPU load may be expected soon,
    113      *     and it may be appropriate to raise speeds of CPU, memory bus,
    114      *     etc.  The data parameter is unused.
    115      *
    116      * POWER_HINT_LOW_POWER
    117      *
    118      *     Low power mode is activated or deactivated. Low power mode
    119      *     is intended to save battery at the cost of performance. The data
    120      *     parameter is non-zero when low power mode is activated, and zero
    121      *     when deactivated.
    122      *
    123      * A particular platform may choose to ignore any hint.
    124      *
    125      * availability: version 0.2
    126      *
    127      */
    128     void (*powerHint)(struct power_module *module, power_hint_t hint,
    129                       void *data);
    130 } power_module_t;
    131 
    132 
    133 __END_DECLS
    134 
    135 #endif  // ANDROID_INCLUDE_HARDWARE_POWER_H
    136