[POWERPC] 4xx: logical/bitand typo in powerpc/boot/4xx.c
[linux-2.6/openmoko-kernel/knife-kernel.git] / kernel / time.c
blob09d3c45c4da78d9af2bec9e10f89e37bfeec01d5
1 /*
2 * linux/kernel/time.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * This file contains the interface functions for the various
7 * time related system calls: time, stime, gettimeofday, settimeofday,
8 * adjtime
9 */
11 * Modification history kernel/time.c
13 * 1993-09-02 Philip Gladstone
14 * Created file with time related functions from sched.c and adjtimex()
15 * 1993-10-08 Torsten Duwe
16 * adjtime interface update and CMOS clock write code
17 * 1995-08-13 Torsten Duwe
18 * kernel PLL updated to 1994-12-13 specs (rfc-1589)
19 * 1999-01-16 Ulrich Windl
20 * Introduced error checking for many cases in adjtimex().
21 * Updated NTP code according to technical memorandum Jan '96
22 * "A Kernel Model for Precision Timekeeping" by Dave Mills
23 * Allow time_constant larger than MAXTC(6) for NTP v4 (MAXTC == 10)
24 * (Even though the technical memorandum forbids it)
25 * 2004-07-14 Christoph Lameter
26 * Added getnstimeofday to allow the posix timer functions to return
27 * with nanosecond accuracy
30 #include <linux/module.h>
31 #include <linux/timex.h>
32 #include <linux/capability.h>
33 #include <linux/clocksource.h>
34 #include <linux/errno.h>
35 #include <linux/syscalls.h>
36 #include <linux/security.h>
37 #include <linux/fs.h>
39 #include <asm/uaccess.h>
40 #include <asm/unistd.h>
43 * The timezone where the local system is located. Used as a default by some
44 * programs who obtain this value by using gettimeofday.
46 struct timezone sys_tz;
48 EXPORT_SYMBOL(sys_tz);
50 #ifdef __ARCH_WANT_SYS_TIME
53 * sys_time() can be implemented in user-level using
54 * sys_gettimeofday(). Is this for backwards compatibility? If so,
55 * why not move it into the appropriate arch directory (for those
56 * architectures that need it).
58 asmlinkage long sys_time(time_t __user * tloc)
60 time_t i = get_seconds();
62 if (tloc) {
63 if (put_user(i,tloc))
64 i = -EFAULT;
66 return i;
70 * sys_stime() can be implemented in user-level using
71 * sys_settimeofday(). Is this for backwards compatibility? If so,
72 * why not move it into the appropriate arch directory (for those
73 * architectures that need it).
76 asmlinkage long sys_stime(time_t __user *tptr)
78 struct timespec tv;
79 int err;
81 if (get_user(tv.tv_sec, tptr))
82 return -EFAULT;
84 tv.tv_nsec = 0;
86 err = security_settime(&tv, NULL);
87 if (err)
88 return err;
90 do_settimeofday(&tv);
91 return 0;
94 #endif /* __ARCH_WANT_SYS_TIME */
96 asmlinkage long sys_gettimeofday(struct timeval __user *tv, struct timezone __user *tz)
98 if (likely(tv != NULL)) {
99 struct timeval ktv;
100 do_gettimeofday(&ktv);
101 if (copy_to_user(tv, &ktv, sizeof(ktv)))
102 return -EFAULT;
104 if (unlikely(tz != NULL)) {
105 if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
106 return -EFAULT;
108 return 0;
112 * Adjust the time obtained from the CMOS to be UTC time instead of
113 * local time.
115 * This is ugly, but preferable to the alternatives. Otherwise we
116 * would either need to write a program to do it in /etc/rc (and risk
117 * confusion if the program gets run more than once; it would also be
118 * hard to make the program warp the clock precisely n hours) or
119 * compile in the timezone information into the kernel. Bad, bad....
121 * - TYT, 1992-01-01
123 * The best thing to do is to keep the CMOS clock in universal time (UTC)
124 * as real UNIX machines always do it. This avoids all headaches about
125 * daylight saving times and warping kernel clocks.
127 static inline void warp_clock(void)
129 write_seqlock_irq(&xtime_lock);
130 wall_to_monotonic.tv_sec -= sys_tz.tz_minuteswest * 60;
131 xtime.tv_sec += sys_tz.tz_minuteswest * 60;
132 write_sequnlock_irq(&xtime_lock);
133 clock_was_set();
137 * In case for some reason the CMOS clock has not already been running
138 * in UTC, but in some local time: The first time we set the timezone,
139 * we will warp the clock so that it is ticking UTC time instead of
140 * local time. Presumably, if someone is setting the timezone then we
141 * are running in an environment where the programs understand about
142 * timezones. This should be done at boot time in the /etc/rc script,
143 * as soon as possible, so that the clock can be set right. Otherwise,
144 * various programs will get confused when the clock gets warped.
147 int do_sys_settimeofday(struct timespec *tv, struct timezone *tz)
149 static int firsttime = 1;
150 int error = 0;
152 if (tv && !timespec_valid(tv))
153 return -EINVAL;
155 error = security_settime(tv, tz);
156 if (error)
157 return error;
159 if (tz) {
160 /* SMP safe, global irq locking makes it work. */
161 sys_tz = *tz;
162 update_vsyscall_tz();
163 if (firsttime) {
164 firsttime = 0;
165 if (!tv)
166 warp_clock();
169 if (tv)
171 /* SMP safe, again the code in arch/foo/time.c should
172 * globally block out interrupts when it runs.
174 return do_settimeofday(tv);
176 return 0;
179 asmlinkage long sys_settimeofday(struct timeval __user *tv,
180 struct timezone __user *tz)
182 struct timeval user_tv;
183 struct timespec new_ts;
184 struct timezone new_tz;
186 if (tv) {
187 if (copy_from_user(&user_tv, tv, sizeof(*tv)))
188 return -EFAULT;
189 new_ts.tv_sec = user_tv.tv_sec;
190 new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
192 if (tz) {
193 if (copy_from_user(&new_tz, tz, sizeof(*tz)))
194 return -EFAULT;
197 return do_sys_settimeofday(tv ? &new_ts : NULL, tz ? &new_tz : NULL);
200 asmlinkage long sys_adjtimex(struct timex __user *txc_p)
202 struct timex txc; /* Local copy of parameter */
203 int ret;
205 /* Copy the user data space into the kernel copy
206 * structure. But bear in mind that the structures
207 * may change
209 if(copy_from_user(&txc, txc_p, sizeof(struct timex)))
210 return -EFAULT;
211 ret = do_adjtimex(&txc);
212 return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret;
216 * current_fs_time - Return FS time
217 * @sb: Superblock.
219 * Return the current time truncated to the time granularity supported by
220 * the fs.
222 struct timespec current_fs_time(struct super_block *sb)
224 struct timespec now = current_kernel_time();
225 return timespec_trunc(now, sb->s_time_gran);
227 EXPORT_SYMBOL(current_fs_time);
230 * Convert jiffies to milliseconds and back.
232 * Avoid unnecessary multiplications/divisions in the
233 * two most common HZ cases:
235 unsigned int inline jiffies_to_msecs(const unsigned long j)
237 #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
238 return (MSEC_PER_SEC / HZ) * j;
239 #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
240 return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC);
241 #else
242 return (j * MSEC_PER_SEC) / HZ;
243 #endif
245 EXPORT_SYMBOL(jiffies_to_msecs);
247 unsigned int inline jiffies_to_usecs(const unsigned long j)
249 #if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ)
250 return (USEC_PER_SEC / HZ) * j;
251 #elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
252 return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC);
253 #else
254 return (j * USEC_PER_SEC) / HZ;
255 #endif
257 EXPORT_SYMBOL(jiffies_to_usecs);
260 * timespec_trunc - Truncate timespec to a granularity
261 * @t: Timespec
262 * @gran: Granularity in ns.
264 * Truncate a timespec to a granularity. gran must be smaller than a second.
265 * Always rounds down.
267 * This function should be only used for timestamps returned by
268 * current_kernel_time() or CURRENT_TIME, not with do_gettimeofday() because
269 * it doesn't handle the better resolution of the later.
271 struct timespec timespec_trunc(struct timespec t, unsigned gran)
274 * Division is pretty slow so avoid it for common cases.
275 * Currently current_kernel_time() never returns better than
276 * jiffies resolution. Exploit that.
278 if (gran <= jiffies_to_usecs(1) * 1000) {
279 /* nothing */
280 } else if (gran == 1000000000) {
281 t.tv_nsec = 0;
282 } else {
283 t.tv_nsec -= t.tv_nsec % gran;
285 return t;
287 EXPORT_SYMBOL(timespec_trunc);
289 #ifndef CONFIG_GENERIC_TIME
291 * Simulate gettimeofday using do_gettimeofday which only allows a timeval
292 * and therefore only yields usec accuracy
294 void getnstimeofday(struct timespec *tv)
296 struct timeval x;
298 do_gettimeofday(&x);
299 tv->tv_sec = x.tv_sec;
300 tv->tv_nsec = x.tv_usec * NSEC_PER_USEC;
302 EXPORT_SYMBOL_GPL(getnstimeofday);
303 #endif
305 /* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
306 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
307 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
309 * [For the Julian calendar (which was used in Russia before 1917,
310 * Britain & colonies before 1752, anywhere else before 1582,
311 * and is still in use by some communities) leave out the
312 * -year/100+year/400 terms, and add 10.]
314 * This algorithm was first published by Gauss (I think).
316 * WARNING: this function will overflow on 2106-02-07 06:28:16 on
317 * machines were long is 32-bit! (However, as time_t is signed, we
318 * will already get problems at other places on 2038-01-19 03:14:08)
320 unsigned long
321 mktime(const unsigned int year0, const unsigned int mon0,
322 const unsigned int day, const unsigned int hour,
323 const unsigned int min, const unsigned int sec)
325 unsigned int mon = mon0, year = year0;
327 /* 1..12 -> 11,12,1..10 */
328 if (0 >= (int) (mon -= 2)) {
329 mon += 12; /* Puts Feb last since it has leap day */
330 year -= 1;
333 return ((((unsigned long)
334 (year/4 - year/100 + year/400 + 367*mon/12 + day) +
335 year*365 - 719499
336 )*24 + hour /* now have hours */
337 )*60 + min /* now have minutes */
338 )*60 + sec; /* finally seconds */
341 EXPORT_SYMBOL(mktime);
344 * set_normalized_timespec - set timespec sec and nsec parts and normalize
346 * @ts: pointer to timespec variable to be set
347 * @sec: seconds to set
348 * @nsec: nanoseconds to set
350 * Set seconds and nanoseconds field of a timespec variable and
351 * normalize to the timespec storage format
353 * Note: The tv_nsec part is always in the range of
354 * 0 <= tv_nsec < NSEC_PER_SEC
355 * For negative values only the tv_sec field is negative !
357 void set_normalized_timespec(struct timespec *ts, time_t sec, long nsec)
359 while (nsec >= NSEC_PER_SEC) {
360 nsec -= NSEC_PER_SEC;
361 ++sec;
363 while (nsec < 0) {
364 nsec += NSEC_PER_SEC;
365 --sec;
367 ts->tv_sec = sec;
368 ts->tv_nsec = nsec;
372 * ns_to_timespec - Convert nanoseconds to timespec
373 * @nsec: the nanoseconds value to be converted
375 * Returns the timespec representation of the nsec parameter.
377 struct timespec ns_to_timespec(const s64 nsec)
379 struct timespec ts;
381 if (!nsec)
382 return (struct timespec) {0, 0};
384 ts.tv_sec = div_long_long_rem_signed(nsec, NSEC_PER_SEC, &ts.tv_nsec);
385 if (unlikely(nsec < 0))
386 set_normalized_timespec(&ts, ts.tv_sec, ts.tv_nsec);
388 return ts;
390 EXPORT_SYMBOL(ns_to_timespec);
393 * ns_to_timeval - Convert nanoseconds to timeval
394 * @nsec: the nanoseconds value to be converted
396 * Returns the timeval representation of the nsec parameter.
398 struct timeval ns_to_timeval(const s64 nsec)
400 struct timespec ts = ns_to_timespec(nsec);
401 struct timeval tv;
403 tv.tv_sec = ts.tv_sec;
404 tv.tv_usec = (suseconds_t) ts.tv_nsec / 1000;
406 return tv;
408 EXPORT_SYMBOL(ns_to_timeval);
411 * When we convert to jiffies then we interpret incoming values
412 * the following way:
414 * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)
416 * - 'too large' values [that would result in larger than
417 * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
419 * - all other values are converted to jiffies by either multiplying
420 * the input value by a factor or dividing it with a factor
422 * We must also be careful about 32-bit overflows.
424 unsigned long msecs_to_jiffies(const unsigned int m)
427 * Negative value, means infinite timeout:
429 if ((int)m < 0)
430 return MAX_JIFFY_OFFSET;
432 #if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
434 * HZ is equal to or smaller than 1000, and 1000 is a nice
435 * round multiple of HZ, divide with the factor between them,
436 * but round upwards:
438 return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ);
439 #elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
441 * HZ is larger than 1000, and HZ is a nice round multiple of
442 * 1000 - simply multiply with the factor between them.
444 * But first make sure the multiplication result cannot
445 * overflow:
447 if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
448 return MAX_JIFFY_OFFSET;
450 return m * (HZ / MSEC_PER_SEC);
451 #else
453 * Generic case - multiply, round and divide. But first
454 * check that if we are doing a net multiplication, that
455 * we wouldnt overflow:
457 if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
458 return MAX_JIFFY_OFFSET;
460 return (m * HZ + MSEC_PER_SEC - 1) / MSEC_PER_SEC;
461 #endif
463 EXPORT_SYMBOL(msecs_to_jiffies);
465 unsigned long usecs_to_jiffies(const unsigned int u)
467 if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET))
468 return MAX_JIFFY_OFFSET;
469 #if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ)
470 return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ);
471 #elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
472 return u * (HZ / USEC_PER_SEC);
473 #else
474 return (u * HZ + USEC_PER_SEC - 1) / USEC_PER_SEC;
475 #endif
477 EXPORT_SYMBOL(usecs_to_jiffies);
480 * The TICK_NSEC - 1 rounds up the value to the next resolution. Note
481 * that a remainder subtract here would not do the right thing as the
482 * resolution values don't fall on second boundries. I.e. the line:
483 * nsec -= nsec % TICK_NSEC; is NOT a correct resolution rounding.
485 * Rather, we just shift the bits off the right.
487 * The >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) converts the scaled nsec
488 * value to a scaled second value.
490 unsigned long
491 timespec_to_jiffies(const struct timespec *value)
493 unsigned long sec = value->tv_sec;
494 long nsec = value->tv_nsec + TICK_NSEC - 1;
496 if (sec >= MAX_SEC_IN_JIFFIES){
497 sec = MAX_SEC_IN_JIFFIES;
498 nsec = 0;
500 return (((u64)sec * SEC_CONVERSION) +
501 (((u64)nsec * NSEC_CONVERSION) >>
502 (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
505 EXPORT_SYMBOL(timespec_to_jiffies);
507 void
508 jiffies_to_timespec(const unsigned long jiffies, struct timespec *value)
511 * Convert jiffies to nanoseconds and separate with
512 * one divide.
514 u64 nsec = (u64)jiffies * TICK_NSEC;
515 value->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &value->tv_nsec);
517 EXPORT_SYMBOL(jiffies_to_timespec);
519 /* Same for "timeval"
521 * Well, almost. The problem here is that the real system resolution is
522 * in nanoseconds and the value being converted is in micro seconds.
523 * Also for some machines (those that use HZ = 1024, in-particular),
524 * there is a LARGE error in the tick size in microseconds.
526 * The solution we use is to do the rounding AFTER we convert the
527 * microsecond part. Thus the USEC_ROUND, the bits to be shifted off.
528 * Instruction wise, this should cost only an additional add with carry
529 * instruction above the way it was done above.
531 unsigned long
532 timeval_to_jiffies(const struct timeval *value)
534 unsigned long sec = value->tv_sec;
535 long usec = value->tv_usec;
537 if (sec >= MAX_SEC_IN_JIFFIES){
538 sec = MAX_SEC_IN_JIFFIES;
539 usec = 0;
541 return (((u64)sec * SEC_CONVERSION) +
542 (((u64)usec * USEC_CONVERSION + USEC_ROUND) >>
543 (USEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
545 EXPORT_SYMBOL(timeval_to_jiffies);
547 void jiffies_to_timeval(const unsigned long jiffies, struct timeval *value)
550 * Convert jiffies to nanoseconds and separate with
551 * one divide.
553 u64 nsec = (u64)jiffies * TICK_NSEC;
554 long tv_usec;
556 value->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &tv_usec);
557 tv_usec /= NSEC_PER_USEC;
558 value->tv_usec = tv_usec;
560 EXPORT_SYMBOL(jiffies_to_timeval);
563 * Convert jiffies/jiffies_64 to clock_t and back.
565 clock_t jiffies_to_clock_t(long x)
567 #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
568 return x / (HZ / USER_HZ);
569 #else
570 u64 tmp = (u64)x * TICK_NSEC;
571 do_div(tmp, (NSEC_PER_SEC / USER_HZ));
572 return (long)tmp;
573 #endif
575 EXPORT_SYMBOL(jiffies_to_clock_t);
577 unsigned long clock_t_to_jiffies(unsigned long x)
579 #if (HZ % USER_HZ)==0
580 if (x >= ~0UL / (HZ / USER_HZ))
581 return ~0UL;
582 return x * (HZ / USER_HZ);
583 #else
584 u64 jif;
586 /* Don't worry about loss of precision here .. */
587 if (x >= ~0UL / HZ * USER_HZ)
588 return ~0UL;
590 /* .. but do try to contain it here */
591 jif = x * (u64) HZ;
592 do_div(jif, USER_HZ);
593 return jif;
594 #endif
596 EXPORT_SYMBOL(clock_t_to_jiffies);
598 u64 jiffies_64_to_clock_t(u64 x)
600 #if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
601 do_div(x, HZ / USER_HZ);
602 #else
604 * There are better ways that don't overflow early,
605 * but even this doesn't overflow in hundreds of years
606 * in 64 bits, so..
608 x *= TICK_NSEC;
609 do_div(x, (NSEC_PER_SEC / USER_HZ));
610 #endif
611 return x;
614 EXPORT_SYMBOL(jiffies_64_to_clock_t);
616 u64 nsec_to_clock_t(u64 x)
618 #if (NSEC_PER_SEC % USER_HZ) == 0
619 do_div(x, (NSEC_PER_SEC / USER_HZ));
620 #elif (USER_HZ % 512) == 0
621 x *= USER_HZ/512;
622 do_div(x, (NSEC_PER_SEC / 512));
623 #else
625 * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024,
626 * overflow after 64.99 years.
627 * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ...
629 x *= 9;
630 do_div(x, (unsigned long)((9ull * NSEC_PER_SEC + (USER_HZ/2)) /
631 USER_HZ));
632 #endif
633 return x;
636 #if (BITS_PER_LONG < 64)
637 u64 get_jiffies_64(void)
639 unsigned long seq;
640 u64 ret;
642 do {
643 seq = read_seqbegin(&xtime_lock);
644 ret = jiffies_64;
645 } while (read_seqretry(&xtime_lock, seq));
646 return ret;
649 EXPORT_SYMBOL(get_jiffies_64);
650 #endif
652 EXPORT_SYMBOL(jiffies);