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 */
setCurrentTimeMillis(int64_t millis)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 */
uptimeMillis()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 */
elapsedRealtime()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
checkTimeStamps(int64_t timestamp,int64_t volatile * prevTimestampPtr,int volatile * prevMethodPtr,int curMethod)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 */
elapsedRealtimeNano()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