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
41namespace android {
42
43/*
44 * native public static long uptimeMillis();
45 */
46int64_t uptimeMillis()
47{
48    int64_t when = systemTime(SYSTEM_TIME_MONOTONIC);
49    return (int64_t) nanoseconds_to_milliseconds(when);
50}
51
52/*
53 * native public static long elapsedRealtime();
54 */
55int64_t elapsedRealtime()
56{
57	return nanoseconds_to_milliseconds(elapsedRealtimeNano());
58}
59
60#define METHOD_CLOCK_GETTIME    0
61#define METHOD_IOCTL            1
62#define METHOD_SYSTEMTIME       2
63
64/*
65 * To debug/verify the timestamps returned by the kernel, change
66 * DEBUG_TIMESTAMP to 1 and call the timestamp routine from a single thread
67 * in the test program. b/10899829
68 */
69#define DEBUG_TIMESTAMP         0
70
71static const char *gettime_method_names[] = {
72    "clock_gettime",
73    "ioctl",
74    "systemTime",
75};
76
77#if DEBUG_TIMESTAMP
78static inline void checkTimeStamps(int64_t timestamp,
79                                   int64_t volatile *prevTimestampPtr,
80                                   int volatile *prevMethodPtr,
81                                   int curMethod)
82{
83    /*
84     * Disable the check for SDK since the prebuilt toolchain doesn't contain
85     * gettid, and int64_t is different on the ARM platform
86     * (ie long vs long long).
87     */
88#ifdef ARCH_ARM
89    int64_t prevTimestamp = *prevTimestampPtr;
90    int prevMethod = *prevMethodPtr;
91
92    if (timestamp < prevTimestamp) {
93        ALOGW("time going backwards: prev %lld(%s) vs now %lld(%s), tid=%d",
94              prevTimestamp, gettime_method_names[prevMethod],
95              timestamp, gettime_method_names[curMethod],
96              gettid());
97    }
98    // NOTE - not atomic and may generate spurious warnings if the 64-bit
99    // write is interrupted or not observed as a whole.
100    *prevTimestampPtr = timestamp;
101    *prevMethodPtr = curMethod;
102#endif
103}
104#else
105#define checkTimeStamps(timestamp, prevTimestampPtr, prevMethodPtr, curMethod)
106#endif
107
108/*
109 * native public static long elapsedRealtimeNano();
110 */
111int64_t elapsedRealtimeNano()
112{
113#ifdef HAVE_ANDROID_OS
114    struct timespec ts;
115    int result;
116    int64_t timestamp;
117#if DEBUG_TIMESTAMP
118    static volatile int64_t prevTimestamp;
119    static volatile int prevMethod;
120#endif
121
122#if 0
123    /*
124     * b/7100774
125     * clock_gettime appears to have clock skews and can sometimes return
126     * backwards values. Disable its use until we find out what's wrong.
127     */
128    result = clock_gettime(CLOCK_BOOTTIME, &ts);
129    if (result == 0) {
130        timestamp = seconds_to_nanoseconds(ts.tv_sec) + ts.tv_nsec;
131        checkTimeStamps(timestamp, &prevTimestamp, &prevMethod,
132                        METHOD_CLOCK_GETTIME);
133        return timestamp;
134    }
135#endif
136
137    // CLOCK_BOOTTIME doesn't exist, fallback to /dev/alarm
138    static int s_fd = -1;
139
140    if (s_fd == -1) {
141        int fd = open("/dev/alarm", O_RDONLY);
142        if (android_atomic_cmpxchg(-1, fd, &s_fd)) {
143            close(fd);
144        }
145    }
146
147    result = ioctl(s_fd,
148            ANDROID_ALARM_GET_TIME(ANDROID_ALARM_ELAPSED_REALTIME), &ts);
149
150    if (result == 0) {
151        timestamp = seconds_to_nanoseconds(ts.tv_sec) + ts.tv_nsec;
152        checkTimeStamps(timestamp, &prevTimestamp, &prevMethod, METHOD_IOCTL);
153        return timestamp;
154    }
155
156    // XXX: there was an error, probably because the driver didn't
157    // exist ... this should return
158    // a real error, like an exception!
159    timestamp = systemTime(SYSTEM_TIME_MONOTONIC);
160    checkTimeStamps(timestamp, &prevTimestamp, &prevMethod,
161                    METHOD_SYSTEMTIME);
162    return timestamp;
163#else
164    return systemTime(SYSTEM_TIME_MONOTONIC);
165#endif
166}
167
168}; // namespace android
169