blob: 379eeb25375db4dfc3f469db68864e4e9f8ad56f
1 | /* 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 source tree. |
8 | */ |
9 | |
10 | #include "libbb.h" |
11 | /* After libbb.h, since it needs sys/types.h on some systems */ |
12 | #include <sys/utsname.h> |
13 | #include "rtc_.h" |
14 | |
15 | /* diff code is disabled: it's not sys/hw clock diff, it's some useless |
16 | * "time between hwclock was started and we saw CMOS tick" quantity. |
17 | * It's useless since hwclock is started at a random moment, |
18 | * thus the quantity is also random, useless. Showing 0.000000 does not |
19 | * deprive us from any useful info. |
20 | * |
21 | * SHOW_HWCLOCK_DIFF code in this file shows the difference between system |
22 | * and hw clock. It is useful, but not compatible with standard hwclock. |
23 | * Thus disabled. |
24 | */ |
25 | #define SHOW_HWCLOCK_DIFF 0 |
26 | |
27 | |
28 | #if !SHOW_HWCLOCK_DIFF |
29 | # define read_rtc(pp_rtcname, sys_tv, utc) read_rtc(pp_rtcname, utc) |
30 | #endif |
31 | static time_t read_rtc(const char **pp_rtcname, struct timeval *sys_tv, int utc) |
32 | { |
33 | struct tm tm_time; |
34 | int fd; |
35 | |
36 | fd = rtc_xopen(pp_rtcname, O_RDONLY); |
37 | |
38 | rtc_read_tm(&tm_time, fd); |
39 | |
40 | #if SHOW_HWCLOCK_DIFF |
41 | { |
42 | int before = tm_time.tm_sec; |
43 | while (1) { |
44 | rtc_read_tm(&tm_time, fd); |
45 | gettimeofday(sys_tv, NULL); |
46 | if (before != (int)tm_time.tm_sec) |
47 | break; |
48 | } |
49 | } |
50 | #endif |
51 | |
52 | if (ENABLE_FEATURE_CLEAN_UP) |
53 | close(fd); |
54 | |
55 | return rtc_tm2time(&tm_time, utc); |
56 | } |
57 | |
58 | static void show_clock(const char **pp_rtcname, int utc) |
59 | { |
60 | #if SHOW_HWCLOCK_DIFF |
61 | struct timeval sys_tv; |
62 | #endif |
63 | time_t t = read_rtc(pp_rtcname, &sys_tv, utc); |
64 | |
65 | #if ENABLE_LOCALE_SUPPORT |
66 | /* Standard hwclock uses locale-specific output format */ |
67 | char cp[64]; |
68 | struct tm *ptm = localtime(&t); |
69 | strftime(cp, sizeof(cp), "%c", ptm); |
70 | #else |
71 | char *cp = ctime(&t); |
72 | strchrnul(cp, '\n')[0] = '\0'; |
73 | #endif |
74 | |
75 | #if !SHOW_HWCLOCK_DIFF |
76 | printf("%s 0.000000 seconds\n", cp); |
77 | #else |
78 | { |
79 | long diff = sys_tv.tv_sec - t; |
80 | if (diff < 0 /*&& tv.tv_usec != 0*/) { |
81 | /* Why we need diff++? */ |
82 | /* diff >= 0 is ok: | diff < 0, can't just use tv.tv_usec: */ |
83 | /* 45.520820 | 43.520820 */ |
84 | /* - 44.000000 | - 45.000000 */ |
85 | /* = 1.520820 | = -1.479180, not -2.520820! */ |
86 | diff++; |
87 | /* Should be 1000000 - tv.tv_usec, but then we must check tv.tv_usec != 0 */ |
88 | sys_tv.tv_usec = 999999 - sys_tv.tv_usec; |
89 | } |
90 | printf("%s %ld.%06lu seconds\n", cp, diff, (unsigned long)sys_tv.tv_usec); |
91 | } |
92 | #endif |
93 | } |
94 | |
95 | static void to_sys_clock(const char **pp_rtcname, int utc) |
96 | { |
97 | struct timeval tv; |
98 | struct timezone tz; |
99 | |
100 | tz.tz_minuteswest = timezone/60 - 60*daylight; |
101 | tz.tz_dsttime = 0; |
102 | |
103 | tv.tv_sec = read_rtc(pp_rtcname, NULL, utc); |
104 | tv.tv_usec = 0; |
105 | if (settimeofday(&tv, &tz)) |
106 | bb_perror_msg_and_die("settimeofday"); |
107 | } |
108 | |
109 | static void from_sys_clock(const char **pp_rtcname, int utc) |
110 | { |
111 | #if 1 |
112 | struct timeval tv; |
113 | struct tm tm_time; |
114 | int rtc; |
115 | |
116 | rtc = rtc_xopen(pp_rtcname, O_WRONLY); |
117 | gettimeofday(&tv, NULL); |
118 | /* Prepare tm_time */ |
119 | if (sizeof(time_t) == sizeof(tv.tv_sec)) { |
120 | if (utc) |
121 | gmtime_r((time_t*)&tv.tv_sec, &tm_time); |
122 | else |
123 | localtime_r((time_t*)&tv.tv_sec, &tm_time); |
124 | } else { |
125 | time_t t = tv.tv_sec; |
126 | if (utc) |
127 | gmtime_r(&t, &tm_time); |
128 | else |
129 | localtime_r(&t, &tm_time); |
130 | } |
131 | #else |
132 | /* Bloated code which tries to set hw clock with better precision. |
133 | * On x86, even though code does set hw clock within <1ms of exact |
134 | * whole seconds, apparently hw clock (at least on some machines) |
135 | * doesn't reset internal fractional seconds to 0, |
136 | * making all this a pointless excercise. |
137 | */ |
138 | /* If we see that we are N usec away from whole second, |
139 | * we'll sleep for N-ADJ usecs. ADJ corrects for the fact |
140 | * that CPU is not infinitely fast. |
141 | * On infinitely fast CPU, next wakeup would be |
142 | * on (exactly_next_whole_second - ADJ). On real CPUs, |
143 | * this difference between current time and whole second |
144 | * is less than ADJ (assuming system isn't heavily loaded). |
145 | */ |
146 | /* Small value of 256us gives very precise sync for 2+ GHz CPUs. |
147 | * Slower CPUs will fail to sync and will go to bigger |
148 | * ADJ values. qemu-emulated armv4tl with ~100 MHz |
149 | * performance ends up using ADJ ~= 4*1024 and it takes |
150 | * 2+ secs (2 tries with successively larger ADJ) |
151 | * to sync. Even straced one on the same qemu (very slow) |
152 | * takes only 4 tries. |
153 | */ |
154 | #define TWEAK_USEC 256 |
155 | unsigned adj = TWEAK_USEC; |
156 | struct tm tm_time; |
157 | struct timeval tv; |
158 | int rtc = rtc_xopen(pp_rtcname, O_WRONLY); |
159 | |
160 | /* Try to catch the moment when whole second is close */ |
161 | while (1) { |
162 | unsigned rem_usec; |
163 | time_t t; |
164 | |
165 | gettimeofday(&tv, NULL); |
166 | |
167 | t = tv.tv_sec; |
168 | rem_usec = 1000000 - tv.tv_usec; |
169 | if (rem_usec < adj) { |
170 | /* Close enough */ |
171 | small_rem: |
172 | t++; |
173 | } |
174 | |
175 | /* Prepare tm_time from t */ |
176 | if (utc) |
177 | gmtime_r(&t, &tm_time); /* may read /etc/xxx (it takes time) */ |
178 | else |
179 | localtime_r(&t, &tm_time); /* same */ |
180 | |
181 | if (adj >= 32*1024) { |
182 | break; /* 32 ms diff and still no luck?? give up trying to sync */ |
183 | } |
184 | |
185 | /* gmtime/localtime took some time, re-get cur time */ |
186 | gettimeofday(&tv, NULL); |
187 | |
188 | if (tv.tv_sec < t /* we are still in old second */ |
189 | || (tv.tv_sec == t && tv.tv_usec < adj) /* not too far into next second */ |
190 | ) { |
191 | break; /* good, we are in sync! */ |
192 | } |
193 | |
194 | rem_usec = 1000000 - tv.tv_usec; |
195 | if (rem_usec < adj) { |
196 | t = tv.tv_sec; |
197 | goto small_rem; /* already close to next sec, don't sleep */ |
198 | } |
199 | |
200 | /* Try to sync up by sleeping */ |
201 | usleep(rem_usec - adj); |
202 | |
203 | /* Jump to 1ms diff, then increase fast (x2): EVERY loop |
204 | * takes ~1 sec, people won't like slowly converging code here! |
205 | */ |
206 | //bb_error_msg("adj:%d tv.tv_usec:%d", adj, (int)tv.tv_usec); |
207 | if (adj < 512) |
208 | adj = 512; |
209 | /* ... and if last "overshoot" does not look insanely big, |
210 | * just use it as adj increment. This makes convergence faster. |
211 | */ |
212 | if (tv.tv_usec < adj * 8) { |
213 | adj += tv.tv_usec; |
214 | continue; |
215 | } |
216 | adj *= 2; |
217 | } |
218 | /* Debug aid to find "optimal" TWEAK_USEC with nearly exact sync. |
219 | * Look for a value which makes tv_usec close to 999999 or 0. |
220 | * For 2.20GHz Intel Core 2: optimal TWEAK_USEC ~= 200 |
221 | */ |
222 | //bb_error_msg("tv.tv_usec:%d", (int)tv.tv_usec); |
223 | #endif |
224 | |
225 | tm_time.tm_isdst = 0; |
226 | xioctl(rtc, RTC_SET_TIME, &tm_time); |
227 | |
228 | if (ENABLE_FEATURE_CLEAN_UP) |
229 | close(rtc); |
230 | } |
231 | |
232 | /* |
233 | * At system boot, kernel may set system time from RTC, |
234 | * but it knows nothing about timezones. If RTC is in local time, |
235 | * then system time is wrong - it is offset by timezone. |
236 | * This option corrects system time if RTC is in local time, |
237 | * and (always) sets in-kernel timezone. |
238 | * |
239 | * This is an alternate option to --hctosys that does not read the |
240 | * hardware clock. |
241 | */ |
242 | static void set_system_clock_timezone(int utc) |
243 | { |
244 | struct timeval tv; |
245 | struct tm *broken; |
246 | struct timezone tz; |
247 | |
248 | gettimeofday(&tv, NULL); |
249 | broken = localtime(&tv.tv_sec); |
250 | tz.tz_minuteswest = timezone / 60; |
251 | if (broken->tm_isdst) |
252 | tz.tz_minuteswest -= 60; |
253 | tz.tz_dsttime = 0; |
254 | gettimeofday(&tv, NULL); |
255 | if (!utc) |
256 | tv.tv_sec += tz.tz_minuteswest * 60; |
257 | if (settimeofday(&tv, &tz)) |
258 | bb_perror_msg_and_die("settimeofday"); |
259 | } |
260 | |
261 | //usage:#define hwclock_trivial_usage |
262 | //usage: IF_FEATURE_HWCLOCK_LONG_OPTIONS( |
263 | //usage: "[-r|--show] [-s|--hctosys] [-w|--systohc] [-t|--systz]" |
264 | //usage: " [-l|--localtime] [-u|--utc]" |
265 | //usage: " [-f|--rtc FILE]" |
266 | //usage: ) |
267 | //usage: IF_NOT_FEATURE_HWCLOCK_LONG_OPTIONS( |
268 | //usage: "[-r] [-s] [-w] [-t] [-l] [-u] [-f FILE]" |
269 | //usage: ) |
270 | //usage:#define hwclock_full_usage "\n\n" |
271 | //usage: "Query and set hardware clock (RTC)\n" |
272 | //usage: "\n -r Show hardware clock time" |
273 | //usage: "\n -s Set system time from hardware clock" |
274 | //usage: "\n -w Set hardware clock from system time" |
275 | //usage: "\n -t Set in-kernel timezone, correct system time" |
276 | //usage: "\n if hardware clock is in local time" |
277 | //usage: "\n -u Assume hardware clock is kept in UTC" |
278 | //usage: "\n -l Assume hardware clock is kept in local time" |
279 | //usage: "\n -f FILE Use specified device (e.g. /dev/rtc2)" |
280 | |
281 | #define HWCLOCK_OPT_LOCALTIME 0x01 |
282 | #define HWCLOCK_OPT_UTC 0x02 |
283 | #define HWCLOCK_OPT_SHOW 0x04 |
284 | #define HWCLOCK_OPT_HCTOSYS 0x08 |
285 | #define HWCLOCK_OPT_SYSTOHC 0x10 |
286 | #define HWCLOCK_OPT_SYSTZ 0x20 |
287 | #define HWCLOCK_OPT_RTCFILE 0x40 |
288 | |
289 | int hwclock_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
290 | int hwclock_main(int argc UNUSED_PARAM, char **argv) |
291 | { |
292 | const char *rtcname = NULL; |
293 | unsigned opt; |
294 | int utc; |
295 | |
296 | #if ENABLE_FEATURE_HWCLOCK_LONG_OPTIONS |
297 | static const char hwclock_longopts[] ALIGN1 = |
298 | "localtime\0" No_argument "l" /* short opt is non-standard */ |
299 | "utc\0" No_argument "u" |
300 | "show\0" No_argument "r" |
301 | "hctosys\0" No_argument "s" |
302 | "systohc\0" No_argument "w" |
303 | "systz\0" No_argument "t" /* short opt is non-standard */ |
304 | "rtc\0" Required_argument "f" |
305 | ; |
306 | applet_long_options = hwclock_longopts; |
307 | #endif |
308 | opt_complementary = "r--wst:w--rst:s--wrt:t--rsw:l--u:u--l"; |
309 | opt = getopt32(argv, "lurswtf:", &rtcname); |
310 | |
311 | /* If -u or -l wasn't given check if we are using utc */ |
312 | if (opt & (HWCLOCK_OPT_UTC | HWCLOCK_OPT_LOCALTIME)) |
313 | utc = (opt & HWCLOCK_OPT_UTC); |
314 | else |
315 | utc = rtc_adjtime_is_utc(); |
316 | |
317 | if (opt & HWCLOCK_OPT_HCTOSYS) |
318 | to_sys_clock(&rtcname, utc); |
319 | else if (opt & HWCLOCK_OPT_SYSTOHC) |
320 | from_sys_clock(&rtcname, utc); |
321 | else if (opt & HWCLOCK_OPT_SYSTZ) |
322 | set_system_clock_timezone(utc); |
323 | else |
324 | /* default HWCLOCK_OPT_SHOW */ |
325 | show_clock(&rtcname, utc); |
326 | |
327 | return 0; |
328 | } |
329 |