Annotation of /trunk/mkinitrd-magellan/busybox/util-linux/hwclock.c
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Revision 990 -
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Sun May 30 11:42:11 2010 UTC (13 years, 11 months ago) by niro
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File size: 7312 byte(s)
Sun May 30 11:42:11 2010 UTC (13 years, 11 months ago) by niro
File MIME type: text/plain
File size: 7312 byte(s)
-added upstream hwclock patch
1 | niro | 532 | /* vi: set sw=4 ts=4: */ |
2 | /* | ||
3 | * Mini hwclock implementation for busybox | ||
4 | * | ||
5 | * Copyright (C) 2002 Robert Griebl <griebl@gmx.de> | ||
6 | * | ||
7 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. | ||
8 | */ | ||
9 | |||
10 | niro | 984 | #include "libbb.h" |
11 | /* After libbb.h, since it needs sys/types.h on some systems */ | ||
12 | niro | 532 | #include <sys/utsname.h> |
13 | niro | 816 | #include "rtc_.h" |
14 | niro | 532 | |
15 | #if ENABLE_FEATURE_HWCLOCK_LONG_OPTIONS | ||
16 | # ifndef _GNU_SOURCE | ||
17 | # define _GNU_SOURCE | ||
18 | # endif | ||
19 | #endif | ||
20 | |||
21 | |||
22 | niro | 984 | /* diff code is disabled: it's not sys/hw clock diff, it's some useless |
23 | * "time between hwclock was started and we saw CMOS tick" quantity. | ||
24 | * It's useless since hwclock is started at a random moment, | ||
25 | * thus the quantity is also random, useless. Showing 0.000000 does not | ||
26 | * deprive us from any useful info. | ||
27 | * | ||
28 | * SHOW_HWCLOCK_DIFF code in this file shows the difference between system | ||
29 | * and hw clock. It is useful, but not compatible with standard hwclock. | ||
30 | * Thus disabled. | ||
31 | */ | ||
32 | #define SHOW_HWCLOCK_DIFF 0 | ||
33 | |||
34 | |||
35 | #if !SHOW_HWCLOCK_DIFF | ||
36 | # define read_rtc(pp_rtcname, sys_tv, utc) read_rtc(pp_rtcname, utc) | ||
37 | #endif | ||
38 | static time_t read_rtc(const char **pp_rtcname, struct timeval *sys_tv, int utc) | ||
39 | niro | 532 | { |
40 | niro | 984 | struct tm tm_time; |
41 | niro | 816 | int fd; |
42 | niro | 532 | |
43 | niro | 984 | fd = rtc_xopen(pp_rtcname, O_RDONLY); |
44 | niro | 532 | |
45 | niro | 984 | rtc_read_tm(&tm_time, fd); |
46 | niro | 532 | |
47 | niro | 984 | #if SHOW_HWCLOCK_DIFF |
48 | { | ||
49 | int before = tm_time.tm_sec; | ||
50 | while (1) { | ||
51 | rtc_read_tm(&tm_time, fd); | ||
52 | gettimeofday(sys_tv, NULL); | ||
53 | if (before != tm_time.tm_sec) | ||
54 | break; | ||
55 | } | ||
56 | } | ||
57 | #endif | ||
58 | niro | 532 | |
59 | niro | 984 | if (ENABLE_FEATURE_CLEAN_UP) |
60 | close(fd); | ||
61 | niro | 532 | |
62 | niro | 984 | return rtc_tm2time(&tm_time, utc); |
63 | niro | 532 | } |
64 | |||
65 | niro | 984 | static void show_clock(const char **pp_rtcname, int utc) |
66 | niro | 532 | { |
67 | niro | 984 | #if SHOW_HWCLOCK_DIFF |
68 | struct timeval sys_tv; | ||
69 | #endif | ||
70 | niro | 532 | time_t t; |
71 | niro | 816 | char *cp; |
72 | niro | 532 | |
73 | niro | 984 | t = read_rtc(pp_rtcname, &sys_tv, utc); |
74 | niro | 816 | cp = ctime(&t); |
75 | niro | 984 | strchrnul(cp, '\n')[0] = '\0'; |
76 | #if !SHOW_HWCLOCK_DIFF | ||
77 | niro | 816 | printf("%s 0.000000 seconds\n", cp); |
78 | niro | 984 | #else |
79 | { | ||
80 | long diff = sys_tv.tv_sec - t; | ||
81 | if (diff < 0 /*&& tv.tv_usec != 0*/) { | ||
82 | /* Why? */ | ||
83 | /* diff >= 0 is ok: diff < 0, can't just use tv.tv_usec: */ | ||
84 | /* 45.520820 43.520820 */ | ||
85 | /* - 44.000000 - 45.000000 */ | ||
86 | /* = 1.520820 = -1.479180, not -2.520820! */ | ||
87 | diff++; | ||
88 | /* should be 1000000 - tv.tv_usec, but then we must check tv.tv_usec != 0 */ | ||
89 | sys_tv.tv_usec = 999999 - sys_tv.tv_usec; | ||
90 | } | ||
91 | printf("%s %ld.%06lu seconds\n", cp, diff, (unsigned long)sys_tv.tv_usec); | ||
92 | } | ||
93 | #endif | ||
94 | niro | 532 | } |
95 | |||
96 | niro | 984 | static void to_sys_clock(const char **pp_rtcname, int utc) |
97 | niro | 532 | { |
98 | niro | 816 | struct timeval tv; |
99 | niro | 984 | struct timezone tz; |
100 | niro | 532 | |
101 | niro | 984 | tz.tz_minuteswest = timezone/60 - 60*daylight; |
102 | tz.tz_dsttime = 0; | ||
103 | |||
104 | tv.tv_sec = read_rtc(pp_rtcname, NULL, utc); | ||
105 | niro | 816 | tv.tv_usec = 0; |
106 | niro | 532 | if (settimeofday(&tv, &tz)) |
107 | niro | 984 | bb_perror_msg_and_die("settimeofday"); |
108 | niro | 532 | } |
109 | |||
110 | niro | 984 | static void from_sys_clock(const char **pp_rtcname, int utc) |
111 | niro | 532 | { |
112 | niro | 990 | #if 1 |
113 | struct timeval tv; | ||
114 | niro | 984 | struct tm tm_time; |
115 | niro | 990 | int rtc; |
116 | |||
117 | rtc = rtc_xopen(pp_rtcname, O_WRONLY); | ||
118 | gettimeofday(&tv, NULL); | ||
119 | /* Prepare tm_time */ | ||
120 | if (sizeof(time_t) == sizeof(tv.tv_sec)) { | ||
121 | if (utc) | ||
122 | gmtime_r((time_t*)&tv.tv_sec, &tm_time); | ||
123 | else | ||
124 | localtime_r((time_t*)&tv.tv_sec, &tm_time); | ||
125 | } else { | ||
126 | time_t t = tv.tv_sec; | ||
127 | if (utc) | ||
128 | gmtime_r(&t, &tm_time); | ||
129 | else | ||
130 | localtime_r(&t, &tm_time); | ||
131 | } | ||
132 | #else | ||
133 | /* Bloated code which tries to set hw clock with better precision. | ||
134 | * On x86, even though code does set hw clock within <1ms of exact | ||
135 | * whole seconds, apparently hw clock (at least on some machines) | ||
136 | * doesn't reset internal fractional seconds to 0, | ||
137 | * making all this a pointless excercise. | ||
138 | */ | ||
139 | /* If we see that we are N usec away from whole second, | ||
140 | * we'll sleep for N-ADJ usecs. ADJ corrects for the fact | ||
141 | * that CPU is not infinitely fast. | ||
142 | * On infinitely fast CPU, next wakeup would be | ||
143 | * on (exactly_next_whole_second - ADJ). On real CPUs, | ||
144 | * this difference between current time and whole second | ||
145 | * is less than ADJ (assuming system isn't heavily loaded). | ||
146 | */ | ||
147 | /* Small value of 256us gives very precise sync for 2+ GHz CPUs. | ||
148 | * Slower CPUs will fail to sync and will go to bigger | ||
149 | * ADJ values. qemu-emulated armv4tl with ~100 MHz | ||
150 | * performance ends up using ADJ ~= 4*1024 and it takes | ||
151 | * 2+ secs (2 tries with successively larger ADJ) | ||
152 | * to sync. Even straced one on the same qemu (very slow) | ||
153 | * takes only 4 tries. | ||
154 | */ | ||
155 | #define TWEAK_USEC 256 | ||
156 | unsigned adj = TWEAK_USEC; | ||
157 | struct tm tm_time; | ||
158 | niro | 816 | struct timeval tv; |
159 | niro | 984 | int rtc = rtc_xopen(pp_rtcname, O_WRONLY); |
160 | niro | 532 | |
161 | niro | 984 | /* Try to catch the moment when whole second is close */ |
162 | while (1) { | ||
163 | unsigned rem_usec; | ||
164 | time_t t; | ||
165 | |||
166 | gettimeofday(&tv, NULL); | ||
167 | |||
168 | t = tv.tv_sec; | ||
169 | rem_usec = 1000000 - tv.tv_usec; | ||
170 | niro | 990 | if (rem_usec < adj) { |
171 | /* Close enough */ | ||
172 | niro | 984 | small_rem: |
173 | t++; | ||
174 | } | ||
175 | |||
176 | niro | 990 | /* Prepare tm_time from t */ |
177 | niro | 984 | if (utc) |
178 | gmtime_r(&t, &tm_time); /* may read /etc/xxx (it takes time) */ | ||
179 | else | ||
180 | localtime_r(&t, &tm_time); /* same */ | ||
181 | |||
182 | niro | 990 | if (adj >= 32*1024) { |
183 | break; /* 32 ms diff and still no luck?? give up trying to sync */ | ||
184 | } | ||
185 | |||
186 | niro | 984 | /* gmtime/localtime took some time, re-get cur time */ |
187 | gettimeofday(&tv, NULL); | ||
188 | |||
189 | niro | 990 | if (tv.tv_sec < t /* we are still in old second */ |
190 | || (tv.tv_sec == t && tv.tv_usec < adj) /* not too far into next second */ | ||
191 | niro | 984 | ) { |
192 | niro | 990 | break; /* good, we are in sync! */ |
193 | niro | 984 | } |
194 | niro | 990 | |
195 | rem_usec = 1000000 - tv.tv_usec; | ||
196 | if (rem_usec < adj) { | ||
197 | t = tv.tv_sec; | ||
198 | goto small_rem; /* already close to next sec, don't sleep */ | ||
199 | niro | 984 | } |
200 | |||
201 | /* Try to sync up by sleeping */ | ||
202 | niro | 990 | usleep(rem_usec - adj); |
203 | |||
204 | /* Jump to 1ms diff, then increase fast (x2): EVERY loop | ||
205 | * takes ~1 sec, people won't like slowly converging code here! | ||
206 | */ | ||
207 | //bb_error_msg("adj:%d tv.tv_usec:%d", adj, (int)tv.tv_usec); | ||
208 | if (adj < 512) | ||
209 | adj = 512; | ||
210 | /* ... and if last "overshoot" does not look insanely big, | ||
211 | * just use it as adj increment. This makes convergence faster. | ||
212 | */ | ||
213 | if (tv.tv_usec < adj * 8) { | ||
214 | adj += tv.tv_usec; | ||
215 | continue; | ||
216 | niro | 984 | } |
217 | niro | 990 | adj *= 2; |
218 | niro | 984 | } |
219 | niro | 990 | /* Debug aid to find "optimal" TWEAK_USEC with nearly exact sync. |
220 | * Look for a value which makes tv_usec close to 999999 or 0. | ||
221 | * For 2.20GHz Intel Core 2: optimal TWEAK_USEC ~= 200 | ||
222 | */ | ||
223 | //bb_error_msg("tv.tv_usec:%d", (int)tv.tv_usec); | ||
224 | #endif | ||
225 | niro | 984 | |
226 | niro | 990 | tm_time.tm_isdst = 0; |
227 | niro | 984 | xioctl(rtc, RTC_SET_TIME, &tm_time); |
228 | |||
229 | if (ENABLE_FEATURE_CLEAN_UP) | ||
230 | close(rtc); | ||
231 | niro | 532 | } |
232 | |||
233 | #define HWCLOCK_OPT_LOCALTIME 0x01 | ||
234 | #define HWCLOCK_OPT_UTC 0x02 | ||
235 | #define HWCLOCK_OPT_SHOW 0x04 | ||
236 | #define HWCLOCK_OPT_HCTOSYS 0x08 | ||
237 | #define HWCLOCK_OPT_SYSTOHC 0x10 | ||
238 | niro | 816 | #define HWCLOCK_OPT_RTCFILE 0x20 |
239 | niro | 532 | |
240 | niro | 816 | int hwclock_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
241 | int hwclock_main(int argc UNUSED_PARAM, char **argv) | ||
242 | niro | 532 | { |
243 | niro | 984 | const char *rtcname = NULL; |
244 | niro | 532 | unsigned opt; |
245 | int utc; | ||
246 | |||
247 | #if ENABLE_FEATURE_HWCLOCK_LONG_OPTIONS | ||
248 | niro | 816 | static const char hwclock_longopts[] ALIGN1 = |
249 | "localtime\0" No_argument "l" | ||
250 | "utc\0" No_argument "u" | ||
251 | "show\0" No_argument "r" | ||
252 | "hctosys\0" No_argument "s" | ||
253 | "systohc\0" No_argument "w" | ||
254 | "file\0" Required_argument "f" | ||
255 | ; | ||
256 | applet_long_options = hwclock_longopts; | ||
257 | niro | 532 | #endif |
258 | niro | 816 | opt_complementary = "r--ws:w--rs:s--wr:l--u:u--l"; |
259 | opt = getopt32(argv, "lurswf:", &rtcname); | ||
260 | niro | 532 | |
261 | /* If -u or -l wasn't given check if we are using utc */ | ||
262 | if (opt & (HWCLOCK_OPT_UTC | HWCLOCK_OPT_LOCALTIME)) | ||
263 | niro | 816 | utc = (opt & HWCLOCK_OPT_UTC); |
264 | niro | 532 | else |
265 | niro | 816 | utc = rtc_adjtime_is_utc(); |
266 | niro | 532 | |
267 | niro | 816 | if (opt & HWCLOCK_OPT_HCTOSYS) |
268 | niro | 984 | to_sys_clock(&rtcname, utc); |
269 | niro | 816 | else if (opt & HWCLOCK_OPT_SYSTOHC) |
270 | niro | 984 | from_sys_clock(&rtcname, utc); |
271 | niro | 816 | else |
272 | niro | 532 | /* default HWCLOCK_OPT_SHOW */ |
273 | niro | 984 | show_clock(&rtcname, utc); |
274 | niro | 816 | |
275 | return 0; | ||
276 | niro | 532 | } |