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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 #include <errno.h>
     18 #include <stdlib.h>
     19 #include <stdio.h>
     20 #include <string.h>
     21 
     22 #include <unistd.h>
     23 #include <fcntl.h>
     24 
     25 #include <utils/Log.h>
     26 
     27 #include "DisplayHardware/DisplayHardwareBase.h"
     28 #include "SurfaceFlinger.h"
     29 
     30 // ----------------------------------------------------------------------------
     31 namespace android {
     32 
     33 static char const * const kSleepFileName = "/sys/power/wait_for_fb_sleep";
     34 static char const * const kWakeFileName  = "/sys/power/wait_for_fb_wake";
     35 
     36 // ----------------------------------------------------------------------------
     37 
     38 DisplayHardwareBase::DisplayEventThread::DisplayEventThread(
     39         const sp<SurfaceFlinger>& flinger)
     40     : Thread(false), mFlinger(flinger) {
     41 }
     42 
     43 DisplayHardwareBase::DisplayEventThread::~DisplayEventThread() {
     44 }
     45 
     46 status_t DisplayHardwareBase::DisplayEventThread::initCheck() const {
     47     return ((access(kSleepFileName, R_OK) == 0 &&
     48             access(kWakeFileName, R_OK) == 0)) ? NO_ERROR : NO_INIT;
     49 }
     50 
     51 bool DisplayHardwareBase::DisplayEventThread::threadLoop() {
     52 
     53     if (waitForFbSleep() == NO_ERROR) {
     54         sp<SurfaceFlinger> flinger = mFlinger.promote();
     55         ALOGD("About to give-up screen, flinger = %p", flinger.get());
     56         if (flinger != 0) {
     57             flinger->screenReleased();
     58         }
     59         if (waitForFbWake() == NO_ERROR) {
     60             ALOGD("Screen about to return, flinger = %p", flinger.get());
     61             if (flinger != 0) {
     62                 flinger->screenAcquired();
     63             }
     64             return true;
     65         }
     66     }
     67 
     68     // error, exit the thread
     69     return false;
     70 }
     71 
     72 status_t DisplayHardwareBase::DisplayEventThread::waitForFbSleep() {
     73     int err = 0;
     74     char buf;
     75     int fd = open(kSleepFileName, O_RDONLY, 0);
     76     // if the file doesn't exist, the error will be caught in read() below
     77     do {
     78         err = read(fd, &buf, 1);
     79     } while (err < 0 && errno == EINTR);
     80     close(fd);
     81     ALOGE_IF(err<0, "*** ANDROID_WAIT_FOR_FB_SLEEP failed (%s)", strerror(errno));
     82     return err < 0 ? -errno : int(NO_ERROR);
     83 }
     84 
     85 status_t DisplayHardwareBase::DisplayEventThread::waitForFbWake() {
     86     int err = 0;
     87     char buf;
     88     int fd = open(kWakeFileName, O_RDONLY, 0);
     89     // if the file doesn't exist, the error will be caught in read() below
     90     do {
     91         err = read(fd, &buf, 1);
     92     } while (err < 0 && errno == EINTR);
     93     close(fd);
     94     ALOGE_IF(err<0, "*** ANDROID_WAIT_FOR_FB_WAKE failed (%s)", strerror(errno));
     95     return err < 0 ? -errno : int(NO_ERROR);
     96 }
     97 
     98 // ----------------------------------------------------------------------------
     99 
    100 DisplayHardwareBase::DisplayHardwareBase(const sp<SurfaceFlinger>& flinger,
    101         uint32_t displayIndex)
    102 {
    103     mScreenAcquired = true;
    104     mDisplayEventThread = new DisplayEventThread(flinger);
    105 }
    106 
    107 void DisplayHardwareBase::startSleepManagement() const {
    108     if (mDisplayEventThread->initCheck() == NO_ERROR) {
    109         mDisplayEventThread->run("DisplayEventThread", PRIORITY_URGENT_DISPLAY);
    110     } else {
    111         ALOGW("/sys/power/wait_for_fb_{wake|sleep} don't exist");
    112     }
    113 }
    114 
    115 DisplayHardwareBase::~DisplayHardwareBase() {
    116     // request exit
    117     mDisplayEventThread->requestExitAndWait();
    118 }
    119 
    120 bool DisplayHardwareBase::canDraw() const {
    121     return mScreenAcquired;
    122 }
    123 
    124 void DisplayHardwareBase::releaseScreen() const {
    125     mScreenAcquired = false;
    126 }
    127 
    128 void DisplayHardwareBase::acquireScreen() const {
    129     mScreenAcquired = true;
    130 }
    131 
    132 bool DisplayHardwareBase::isScreenAcquired() const {
    133     return mScreenAcquired;
    134 }
    135 
    136 }; // namespace android
    137