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      1 /*
      2  * Copyright (C) 2008 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 
     18 /*
     19  * System clock functions.
     20  */
     21 
     22 #ifdef HAVE_ANDROID_OS
     23 #include <linux/ioctl.h>
     24 #include <linux/rtc.h>
     25 #include <utils/Atomic.h>
     26 #include <linux/android_alarm.h>
     27 #endif
     28 
     29 #include <sys/time.h>
     30 #include <limits.h>
     31 #include <fcntl.h>
     32 #include <errno.h>
     33 #include <string.h>
     34 
     35 #include <utils/SystemClock.h>
     36 #include <utils/Timers.h>
     37 
     38 #define LOG_TAG "SystemClock"
     39 #include "utils/Log.h"
     40 
     41 namespace android {
     42 
     43 /*
     44  * Set the current time.  This only works when running as root.
     45  */
     46 int setCurrentTimeMillis(int64_t millis)
     47 {
     48 #if WIN32
     49     // not implemented
     50     return -1;
     51 #else
     52     struct timeval tv;
     53 #ifdef HAVE_ANDROID_OS
     54     struct timespec ts;
     55     int fd;
     56     int res;
     57 #endif
     58     int ret = 0;
     59 
     60     if (millis <= 0 || millis / 1000LL >= INT_MAX) {
     61         return -1;
     62     }
     63 
     64     tv.tv_sec = (time_t) (millis / 1000LL);
     65     tv.tv_usec = (suseconds_t) ((millis % 1000LL) * 1000LL);
     66 
     67     ALOGD("Setting time of day to sec=%d\n", (int) tv.tv_sec);
     68 
     69 #ifdef HAVE_ANDROID_OS
     70     fd = open("/dev/alarm", O_RDWR);
     71     if(fd < 0) {
     72         ALOGW("Unable to open alarm driver: %s\n", strerror(errno));
     73         return -1;
     74     }
     75     ts.tv_sec = tv.tv_sec;
     76     ts.tv_nsec = tv.tv_usec * 1000;
     77     res = ioctl(fd, ANDROID_ALARM_SET_RTC, &ts);
     78     if(res < 0) {
     79         ALOGW("Unable to set rtc to %ld: %s\n", tv.tv_sec, strerror(errno));
     80         ret = -1;
     81     }
     82     close(fd);
     83 #else
     84     if (settimeofday(&tv, NULL) != 0) {
     85         ALOGW("Unable to set clock to %d.%d: %s\n",
     86             (int) tv.tv_sec, (int) tv.tv_usec, strerror(errno));
     87         ret = -1;
     88     }
     89 #endif
     90 
     91     return ret;
     92 #endif // WIN32
     93 }
     94 
     95 /*
     96  * native public static long uptimeMillis();
     97  */
     98 int64_t uptimeMillis()
     99 {
    100     int64_t when = systemTime(SYSTEM_TIME_MONOTONIC);
    101     return (int64_t) nanoseconds_to_milliseconds(when);
    102 }
    103 
    104 /*
    105  * native public static long elapsedRealtime();
    106  */
    107 int64_t elapsedRealtime()
    108 {
    109 	return nanoseconds_to_milliseconds(elapsedRealtimeNano());
    110 }
    111 
    112 #define METHOD_CLOCK_GETTIME    0
    113 #define METHOD_IOCTL            1
    114 #define METHOD_SYSTEMTIME       2
    115 
    116 static const char *gettime_method_names[] = {
    117     "clock_gettime",
    118     "ioctl",
    119     "systemTime",
    120 };
    121 
    122 static inline void checkTimeStamps(int64_t timestamp,
    123                                    int64_t volatile *prevTimestampPtr,
    124                                    int volatile *prevMethodPtr,
    125                                    int curMethod)
    126 {
    127     /*
    128      * Disable the check for SDK since the prebuilt toolchain doesn't contain
    129      * gettid, and int64_t is different on the ARM platform
    130      * (ie long vs long long).
    131      */
    132 #ifdef ARCH_ARM
    133     int64_t prevTimestamp = *prevTimestampPtr;
    134     int prevMethod = *prevMethodPtr;
    135 
    136     if (timestamp < prevTimestamp) {
    137         ALOGW("time going backwards: prev %lld(%s) vs now %lld(%s), tid=%d",
    138               prevTimestamp, gettime_method_names[prevMethod],
    139               timestamp, gettime_method_names[curMethod],
    140               gettid());
    141     }
    142     // NOTE - not atomic and may generate spurious warnings if the 64-bit
    143     // write is interrupted or not observed as a whole.
    144     *prevTimestampPtr = timestamp;
    145     *prevMethodPtr = curMethod;
    146 #endif
    147 }
    148 
    149 /*
    150  * native public static long elapsedRealtimeNano();
    151  */
    152 int64_t elapsedRealtimeNano()
    153 {
    154 #ifdef HAVE_ANDROID_OS
    155     struct timespec ts;
    156     int result;
    157     int64_t timestamp;
    158     static volatile int64_t prevTimestamp;
    159     static volatile int prevMethod;
    160 
    161 #if 0
    162     /*
    163      * b/7100774
    164      * clock_gettime appears to have clock skews and can sometimes return
    165      * backwards values. Disable its use until we find out what's wrong.
    166      */
    167     result = clock_gettime(CLOCK_BOOTTIME, &ts);
    168     if (result == 0) {
    169         timestamp = seconds_to_nanoseconds(ts.tv_sec) + ts.tv_nsec;
    170         checkTimeStamps(timestamp, &prevTimestamp, &prevMethod,
    171                         METHOD_CLOCK_GETTIME);
    172         return timestamp;
    173     }
    174 #endif
    175 
    176     // CLOCK_BOOTTIME doesn't exist, fallback to /dev/alarm
    177     static int s_fd = -1;
    178 
    179     if (s_fd == -1) {
    180         int fd = open("/dev/alarm", O_RDONLY);
    181         if (android_atomic_cmpxchg(-1, fd, &s_fd)) {
    182             close(fd);
    183         }
    184     }
    185 
    186     result = ioctl(s_fd,
    187             ANDROID_ALARM_GET_TIME(ANDROID_ALARM_ELAPSED_REALTIME), &ts);
    188 
    189     if (result == 0) {
    190         timestamp = seconds_to_nanoseconds(ts.tv_sec) + ts.tv_nsec;
    191         checkTimeStamps(timestamp, &prevTimestamp, &prevMethod, METHOD_IOCTL);
    192         return timestamp;
    193     }
    194 
    195     // XXX: there was an error, probably because the driver didn't
    196     // exist ... this should return
    197     // a real error, like an exception!
    198     timestamp = systemTime(SYSTEM_TIME_MONOTONIC);
    199     checkTimeStamps(timestamp, &prevTimestamp, &prevMethod,
    200                     METHOD_SYSTEMTIME);
    201     return timestamp;
    202 #else
    203     return systemTime(SYSTEM_TIME_MONOTONIC);
    204 #endif
    205 }
    206 
    207 }; // namespace android
    208