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