Contents of /trunk/mkinitrd-magellan/busybox/util-linux/hwclock.c
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Revision 984 -
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Sun May 30 11:32:42 2010 UTC (13 years, 11 months ago) by niro
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File size: 5645 byte(s)
Sun May 30 11:32:42 2010 UTC (13 years, 11 months ago) by niro
File MIME type: text/plain
File size: 5645 byte(s)
-updated to busybox-1.16.1 and enabled blkid/uuid support in default config
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 tarball for details. |
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 | #if ENABLE_FEATURE_HWCLOCK_LONG_OPTIONS |
16 | # ifndef _GNU_SOURCE |
17 | # define _GNU_SOURCE |
18 | # endif |
19 | #endif |
20 | |
21 | |
22 | /* 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 | { |
40 | struct tm tm_time; |
41 | int fd; |
42 | |
43 | fd = rtc_xopen(pp_rtcname, O_RDONLY); |
44 | |
45 | rtc_read_tm(&tm_time, fd); |
46 | |
47 | #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 | |
59 | if (ENABLE_FEATURE_CLEAN_UP) |
60 | close(fd); |
61 | |
62 | return rtc_tm2time(&tm_time, utc); |
63 | } |
64 | |
65 | static void show_clock(const char **pp_rtcname, int utc) |
66 | { |
67 | #if SHOW_HWCLOCK_DIFF |
68 | struct timeval sys_tv; |
69 | #endif |
70 | time_t t; |
71 | char *cp; |
72 | |
73 | t = read_rtc(pp_rtcname, &sys_tv, utc); |
74 | cp = ctime(&t); |
75 | strchrnul(cp, '\n')[0] = '\0'; |
76 | #if !SHOW_HWCLOCK_DIFF |
77 | printf("%s 0.000000 seconds\n", cp); |
78 | #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 | } |
95 | |
96 | static void to_sys_clock(const char **pp_rtcname, int utc) |
97 | { |
98 | struct timeval tv; |
99 | struct timezone tz; |
100 | |
101 | tz.tz_minuteswest = timezone/60 - 60*daylight; |
102 | tz.tz_dsttime = 0; |
103 | |
104 | tv.tv_sec = read_rtc(pp_rtcname, NULL, utc); |
105 | tv.tv_usec = 0; |
106 | if (settimeofday(&tv, &tz)) |
107 | bb_perror_msg_and_die("settimeofday"); |
108 | } |
109 | |
110 | static void from_sys_clock(const char **pp_rtcname, int utc) |
111 | { |
112 | #define TWEAK_USEC 200 |
113 | struct tm tm_time; |
114 | struct timeval tv; |
115 | unsigned adj = TWEAK_USEC; |
116 | int rtc = rtc_xopen(pp_rtcname, O_WRONLY); |
117 | |
118 | /* Try to catch the moment when whole second is close */ |
119 | while (1) { |
120 | unsigned rem_usec; |
121 | time_t t; |
122 | |
123 | gettimeofday(&tv, NULL); |
124 | |
125 | t = tv.tv_sec; |
126 | rem_usec = 1000000 - tv.tv_usec; |
127 | if (rem_usec < 1024) { |
128 | /* Less than 1ms to next second. Good enough */ |
129 | small_rem: |
130 | t++; |
131 | } |
132 | |
133 | /* Prepare tm */ |
134 | if (utc) |
135 | gmtime_r(&t, &tm_time); /* may read /etc/xxx (it takes time) */ |
136 | else |
137 | localtime_r(&t, &tm_time); /* same */ |
138 | tm_time.tm_isdst = 0; |
139 | |
140 | /* gmtime/localtime took some time, re-get cur time */ |
141 | gettimeofday(&tv, NULL); |
142 | |
143 | if (tv.tv_sec < t /* may happen if rem_usec was < 1024 */ |
144 | || (tv.tv_sec == t && tv.tv_usec < 1024) |
145 | ) { |
146 | /* We are not too far into next second. Good. */ |
147 | break; |
148 | } |
149 | adj += 32; /* 2^(10-5) = 2^5 = 32 iterations max */ |
150 | if (adj >= 1024) { |
151 | /* Give up trying to sync */ |
152 | break; |
153 | } |
154 | |
155 | /* Try to sync up by sleeping */ |
156 | rem_usec = 1000000 - tv.tv_usec; |
157 | if (rem_usec < 1024) { |
158 | goto small_rem; /* already close, don't sleep */ |
159 | } |
160 | /* Need to sleep. |
161 | * Note that small adj on slow processors can make us |
162 | * to always overshoot tv.tv_usec < 1024 check on next |
163 | * iteration. That's why adj is increased on each iteration. |
164 | * This also allows it to be reused as a loop limiter. |
165 | */ |
166 | usleep(rem_usec - adj); |
167 | } |
168 | |
169 | xioctl(rtc, RTC_SET_TIME, &tm_time); |
170 | |
171 | /* Debug aid to find "good" TWEAK_USEC. |
172 | * Look for a value which makes tv_usec close to 999999 or 0. |
173 | * for 2.20GHz Intel Core 2: TWEAK_USEC ~= 200 |
174 | */ |
175 | //bb_error_msg("tv.tv_usec:%d adj:%d", (int)tv.tv_usec, adj); |
176 | |
177 | if (ENABLE_FEATURE_CLEAN_UP) |
178 | close(rtc); |
179 | } |
180 | |
181 | #define HWCLOCK_OPT_LOCALTIME 0x01 |
182 | #define HWCLOCK_OPT_UTC 0x02 |
183 | #define HWCLOCK_OPT_SHOW 0x04 |
184 | #define HWCLOCK_OPT_HCTOSYS 0x08 |
185 | #define HWCLOCK_OPT_SYSTOHC 0x10 |
186 | #define HWCLOCK_OPT_RTCFILE 0x20 |
187 | |
188 | int hwclock_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
189 | int hwclock_main(int argc UNUSED_PARAM, char **argv) |
190 | { |
191 | const char *rtcname = NULL; |
192 | unsigned opt; |
193 | int utc; |
194 | |
195 | #if ENABLE_FEATURE_HWCLOCK_LONG_OPTIONS |
196 | static const char hwclock_longopts[] ALIGN1 = |
197 | "localtime\0" No_argument "l" |
198 | "utc\0" No_argument "u" |
199 | "show\0" No_argument "r" |
200 | "hctosys\0" No_argument "s" |
201 | "systohc\0" No_argument "w" |
202 | "file\0" Required_argument "f" |
203 | ; |
204 | applet_long_options = hwclock_longopts; |
205 | #endif |
206 | opt_complementary = "r--ws:w--rs:s--wr:l--u:u--l"; |
207 | opt = getopt32(argv, "lurswf:", &rtcname); |
208 | |
209 | /* If -u or -l wasn't given check if we are using utc */ |
210 | if (opt & (HWCLOCK_OPT_UTC | HWCLOCK_OPT_LOCALTIME)) |
211 | utc = (opt & HWCLOCK_OPT_UTC); |
212 | else |
213 | utc = rtc_adjtime_is_utc(); |
214 | |
215 | if (opt & HWCLOCK_OPT_HCTOSYS) |
216 | to_sys_clock(&rtcname, utc); |
217 | else if (opt & HWCLOCK_OPT_SYSTOHC) |
218 | from_sys_clock(&rtcname, utc); |
219 | else |
220 | /* default HWCLOCK_OPT_SHOW */ |
221 | show_clock(&rtcname, utc); |
222 | |
223 | return 0; |
224 | } |