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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/kernel/time.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 *
6 * This file contains the interface functions for the various
7 * time related system calls: time, stime, gettimeofday, settimeofday,
8 * adjtime
9 */
10/*
11 * Modification history kernel/time.c
Daniel Walker6fa6c3b2007-10-18 03:06:03 -070012 *
Linus Torvalds1da177e2005-04-16 15:20:36 -070013 * 1993-09-02 Philip Gladstone
Daniel Walker6fa6c3b2007-10-18 03:06:03 -070014 * Created file with time related functions from sched.c and adjtimex()
Linus Torvalds1da177e2005-04-16 15:20:36 -070015 * 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
28 */
29
30#include <linux/module.h>
31#include <linux/timex.h>
Randy.Dunlapc59ede72006-01-11 12:17:46 -080032#include <linux/capability.h>
Tony Breeds2c622142007-10-18 03:04:57 -070033#include <linux/clocksource.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070034#include <linux/errno.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070035#include <linux/syscalls.h>
36#include <linux/security.h>
37#include <linux/fs.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070038
39#include <asm/uaccess.h>
40#include <asm/unistd.h>
41
Daniel Walker6fa6c3b2007-10-18 03:06:03 -070042/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070043 * The timezone where the local system is located. Used as a default by some
44 * programs who obtain this value by using gettimeofday.
45 */
46struct timezone sys_tz;
47
48EXPORT_SYMBOL(sys_tz);
49
50#ifdef __ARCH_WANT_SYS_TIME
51
52/*
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).
57 */
58asmlinkage long sys_time(time_t __user * tloc)
59{
Ingo Molnarf20bf612007-10-16 16:09:20 +020060 time_t i = get_seconds();
Linus Torvalds1da177e2005-04-16 15:20:36 -070061
62 if (tloc) {
Linus Torvalds20082202007-07-20 13:28:54 -070063 if (put_user(i,tloc))
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 i = -EFAULT;
65 }
66 return i;
67}
68
69/*
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).
74 */
Daniel Walker6fa6c3b2007-10-18 03:06:03 -070075
Linus Torvalds1da177e2005-04-16 15:20:36 -070076asmlinkage long sys_stime(time_t __user *tptr)
77{
78 struct timespec tv;
79 int err;
80
81 if (get_user(tv.tv_sec, tptr))
82 return -EFAULT;
83
84 tv.tv_nsec = 0;
85
86 err = security_settime(&tv, NULL);
87 if (err)
88 return err;
89
90 do_settimeofday(&tv);
91 return 0;
92}
93
94#endif /* __ARCH_WANT_SYS_TIME */
95
96asmlinkage long sys_gettimeofday(struct timeval __user *tv, struct timezone __user *tz)
97{
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;
103 }
104 if (unlikely(tz != NULL)) {
105 if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
106 return -EFAULT;
107 }
108 return 0;
109}
110
111/*
112 * Adjust the time obtained from the CMOS to be UTC time instead of
113 * local time.
Daniel Walker6fa6c3b2007-10-18 03:06:03 -0700114 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700115 * 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
Daniel Walker6fa6c3b2007-10-18 03:06:03 -0700117 * confusion if the program gets run more than once; it would also be
Linus Torvalds1da177e2005-04-16 15:20:36 -0700118 * hard to make the program warp the clock precisely n hours) or
119 * compile in the timezone information into the kernel. Bad, bad....
120 *
121 * - TYT, 1992-01-01
122 *
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.
126 */
Jesper Juhl77933d72005-07-27 11:46:09 -0700127static inline void warp_clock(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128{
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;
Thomas Gleixner1001d0a2008-02-01 17:45:13 +0100132 update_xtime_cache(0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133 write_sequnlock_irq(&xtime_lock);
134 clock_was_set();
135}
136
137/*
138 * In case for some reason the CMOS clock has not already been running
139 * in UTC, but in some local time: The first time we set the timezone,
140 * we will warp the clock so that it is ticking UTC time instead of
141 * local time. Presumably, if someone is setting the timezone then we
142 * are running in an environment where the programs understand about
143 * timezones. This should be done at boot time in the /etc/rc script,
144 * as soon as possible, so that the clock can be set right. Otherwise,
145 * various programs will get confused when the clock gets warped.
146 */
147
148int do_sys_settimeofday(struct timespec *tv, struct timezone *tz)
149{
150 static int firsttime = 1;
151 int error = 0;
152
Linus Torvalds951069e2006-01-31 10:16:55 -0800153 if (tv && !timespec_valid(tv))
Thomas Gleixner718bcce2006-01-09 20:52:29 -0800154 return -EINVAL;
155
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 error = security_settime(tv, tz);
157 if (error)
158 return error;
159
160 if (tz) {
161 /* SMP safe, global irq locking makes it work. */
162 sys_tz = *tz;
Tony Breeds2c622142007-10-18 03:04:57 -0700163 update_vsyscall_tz();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700164 if (firsttime) {
165 firsttime = 0;
166 if (!tv)
167 warp_clock();
168 }
169 }
170 if (tv)
171 {
172 /* SMP safe, again the code in arch/foo/time.c should
173 * globally block out interrupts when it runs.
174 */
175 return do_settimeofday(tv);
176 }
177 return 0;
178}
179
180asmlinkage long sys_settimeofday(struct timeval __user *tv,
181 struct timezone __user *tz)
182{
183 struct timeval user_tv;
184 struct timespec new_ts;
185 struct timezone new_tz;
186
187 if (tv) {
188 if (copy_from_user(&user_tv, tv, sizeof(*tv)))
189 return -EFAULT;
190 new_ts.tv_sec = user_tv.tv_sec;
191 new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
192 }
193 if (tz) {
194 if (copy_from_user(&new_tz, tz, sizeof(*tz)))
195 return -EFAULT;
196 }
197
198 return do_sys_settimeofday(tv ? &new_ts : NULL, tz ? &new_tz : NULL);
199}
200
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201asmlinkage long sys_adjtimex(struct timex __user *txc_p)
202{
203 struct timex txc; /* Local copy of parameter */
204 int ret;
205
206 /* Copy the user data space into the kernel copy
207 * structure. But bear in mind that the structures
208 * may change
209 */
210 if(copy_from_user(&txc, txc_p, sizeof(struct timex)))
211 return -EFAULT;
212 ret = do_adjtimex(&txc);
213 return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret;
214}
215
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216/**
217 * current_fs_time - Return FS time
218 * @sb: Superblock.
219 *
Kalin KOZHUHAROV8ba8e952006-04-01 01:41:22 +0200220 * Return the current time truncated to the time granularity supported by
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221 * the fs.
222 */
223struct timespec current_fs_time(struct super_block *sb)
224{
225 struct timespec now = current_kernel_time();
226 return timespec_trunc(now, sb->s_time_gran);
227}
228EXPORT_SYMBOL(current_fs_time);
229
Eric Dumazet753e9c52007-05-08 00:25:32 -0700230/*
231 * Convert jiffies to milliseconds and back.
232 *
233 * Avoid unnecessary multiplications/divisions in the
234 * two most common HZ cases:
235 */
236unsigned int inline jiffies_to_msecs(const unsigned long j)
237{
238#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
239 return (MSEC_PER_SEC / HZ) * j;
240#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
241 return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC);
242#else
243 return (j * MSEC_PER_SEC) / HZ;
244#endif
245}
246EXPORT_SYMBOL(jiffies_to_msecs);
247
248unsigned int inline jiffies_to_usecs(const unsigned long j)
249{
250#if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ)
251 return (USEC_PER_SEC / HZ) * j;
252#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
253 return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC);
254#else
255 return (j * USEC_PER_SEC) / HZ;
256#endif
257}
258EXPORT_SYMBOL(jiffies_to_usecs);
259
Linus Torvalds1da177e2005-04-16 15:20:36 -0700260/**
Kalin KOZHUHAROV8ba8e952006-04-01 01:41:22 +0200261 * timespec_trunc - Truncate timespec to a granularity
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 * @t: Timespec
Kalin KOZHUHAROV8ba8e952006-04-01 01:41:22 +0200263 * @gran: Granularity in ns.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264 *
Kalin KOZHUHAROV8ba8e952006-04-01 01:41:22 +0200265 * Truncate a timespec to a granularity. gran must be smaller than a second.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266 * Always rounds down.
267 *
268 * This function should be only used for timestamps returned by
269 * current_kernel_time() or CURRENT_TIME, not with do_gettimeofday() because
270 * it doesn't handle the better resolution of the later.
271 */
272struct timespec timespec_trunc(struct timespec t, unsigned gran)
273{
274 /*
275 * Division is pretty slow so avoid it for common cases.
276 * Currently current_kernel_time() never returns better than
277 * jiffies resolution. Exploit that.
278 */
279 if (gran <= jiffies_to_usecs(1) * 1000) {
280 /* nothing */
281 } else if (gran == 1000000000) {
282 t.tv_nsec = 0;
283 } else {
284 t.tv_nsec -= t.tv_nsec % gran;
285 }
286 return t;
287}
288EXPORT_SYMBOL(timespec_trunc);
289
john stultzcf3c7692006-06-26 00:25:08 -0700290#ifndef CONFIG_GENERIC_TIME
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291/*
292 * Simulate gettimeofday using do_gettimeofday which only allows a timeval
293 * and therefore only yields usec accuracy
294 */
295void getnstimeofday(struct timespec *tv)
296{
297 struct timeval x;
298
299 do_gettimeofday(&x);
300 tv->tv_sec = x.tv_sec;
301 tv->tv_nsec = x.tv_usec * NSEC_PER_USEC;
302}
Takashi Iwaic6ecf7e2005-10-14 15:59:03 -0700303EXPORT_SYMBOL_GPL(getnstimeofday);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700304#endif
305
Thomas Gleixner753be622006-01-09 20:52:22 -0800306/* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
307 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
308 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
309 *
310 * [For the Julian calendar (which was used in Russia before 1917,
311 * Britain & colonies before 1752, anywhere else before 1582,
312 * and is still in use by some communities) leave out the
313 * -year/100+year/400 terms, and add 10.]
314 *
315 * This algorithm was first published by Gauss (I think).
316 *
317 * WARNING: this function will overflow on 2106-02-07 06:28:16 on
318 * machines were long is 32-bit! (However, as time_t is signed, we
319 * will already get problems at other places on 2038-01-19 03:14:08)
320 */
321unsigned long
Ingo Molnarf4818902006-01-09 20:52:23 -0800322mktime(const unsigned int year0, const unsigned int mon0,
323 const unsigned int day, const unsigned int hour,
324 const unsigned int min, const unsigned int sec)
Thomas Gleixner753be622006-01-09 20:52:22 -0800325{
Ingo Molnarf4818902006-01-09 20:52:23 -0800326 unsigned int mon = mon0, year = year0;
327
328 /* 1..12 -> 11,12,1..10 */
329 if (0 >= (int) (mon -= 2)) {
330 mon += 12; /* Puts Feb last since it has leap day */
Thomas Gleixner753be622006-01-09 20:52:22 -0800331 year -= 1;
332 }
333
334 return ((((unsigned long)
335 (year/4 - year/100 + year/400 + 367*mon/12 + day) +
336 year*365 - 719499
337 )*24 + hour /* now have hours */
338 )*60 + min /* now have minutes */
339 )*60 + sec; /* finally seconds */
340}
341
Andrew Morton199e7052006-01-09 20:52:24 -0800342EXPORT_SYMBOL(mktime);
343
Thomas Gleixner753be622006-01-09 20:52:22 -0800344/**
345 * set_normalized_timespec - set timespec sec and nsec parts and normalize
346 *
347 * @ts: pointer to timespec variable to be set
348 * @sec: seconds to set
349 * @nsec: nanoseconds to set
350 *
351 * Set seconds and nanoseconds field of a timespec variable and
352 * normalize to the timespec storage format
353 *
354 * Note: The tv_nsec part is always in the range of
355 * 0 <= tv_nsec < NSEC_PER_SEC
356 * For negative values only the tv_sec field is negative !
357 */
Ingo Molnarf4818902006-01-09 20:52:23 -0800358void set_normalized_timespec(struct timespec *ts, time_t sec, long nsec)
Thomas Gleixner753be622006-01-09 20:52:22 -0800359{
360 while (nsec >= NSEC_PER_SEC) {
361 nsec -= NSEC_PER_SEC;
362 ++sec;
363 }
364 while (nsec < 0) {
365 nsec += NSEC_PER_SEC;
366 --sec;
367 }
368 ts->tv_sec = sec;
369 ts->tv_nsec = nsec;
370}
371
Thomas Gleixnerf8f46da2006-01-09 20:52:30 -0800372/**
373 * ns_to_timespec - Convert nanoseconds to timespec
374 * @nsec: the nanoseconds value to be converted
375 *
376 * Returns the timespec representation of the nsec parameter.
377 */
Roman Zippeldf869b62006-03-26 01:38:11 -0800378struct timespec ns_to_timespec(const s64 nsec)
Thomas Gleixnerf8f46da2006-01-09 20:52:30 -0800379{
380 struct timespec ts;
381
George Anzinger88fc3892006-02-03 03:04:20 -0800382 if (!nsec)
383 return (struct timespec) {0, 0};
384
385 ts.tv_sec = div_long_long_rem_signed(nsec, NSEC_PER_SEC, &ts.tv_nsec);
386 if (unlikely(nsec < 0))
387 set_normalized_timespec(&ts, ts.tv_sec, ts.tv_nsec);
Thomas Gleixnerf8f46da2006-01-09 20:52:30 -0800388
389 return ts;
390}
Stephen Hemminger85795d62007-03-24 21:35:33 -0700391EXPORT_SYMBOL(ns_to_timespec);
Thomas Gleixnerf8f46da2006-01-09 20:52:30 -0800392
393/**
394 * ns_to_timeval - Convert nanoseconds to timeval
395 * @nsec: the nanoseconds value to be converted
396 *
397 * Returns the timeval representation of the nsec parameter.
398 */
Roman Zippeldf869b62006-03-26 01:38:11 -0800399struct timeval ns_to_timeval(const s64 nsec)
Thomas Gleixnerf8f46da2006-01-09 20:52:30 -0800400{
401 struct timespec ts = ns_to_timespec(nsec);
402 struct timeval tv;
403
404 tv.tv_sec = ts.tv_sec;
405 tv.tv_usec = (suseconds_t) ts.tv_nsec / 1000;
406
407 return tv;
408}
Eric Dumazetb7aa0bf2007-04-19 16:16:32 -0700409EXPORT_SYMBOL(ns_to_timeval);
Thomas Gleixnerf8f46da2006-01-09 20:52:30 -0800410
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800411/*
Ingo Molnar41cf5442007-02-16 01:27:28 -0800412 * When we convert to jiffies then we interpret incoming values
413 * the following way:
414 *
415 * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)
416 *
417 * - 'too large' values [that would result in larger than
418 * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
419 *
420 * - all other values are converted to jiffies by either multiplying
421 * the input value by a factor or dividing it with a factor
422 *
423 * We must also be careful about 32-bit overflows.
424 */
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800425unsigned long msecs_to_jiffies(const unsigned int m)
426{
Ingo Molnar41cf5442007-02-16 01:27:28 -0800427 /*
428 * Negative value, means infinite timeout:
429 */
430 if ((int)m < 0)
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800431 return MAX_JIFFY_OFFSET;
Ingo Molnar41cf5442007-02-16 01:27:28 -0800432
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800433#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
Ingo Molnar41cf5442007-02-16 01:27:28 -0800434 /*
435 * HZ is equal to or smaller than 1000, and 1000 is a nice
436 * round multiple of HZ, divide with the factor between them,
437 * but round upwards:
438 */
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800439 return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ);
440#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
Ingo Molnar41cf5442007-02-16 01:27:28 -0800441 /*
442 * HZ is larger than 1000, and HZ is a nice round multiple of
443 * 1000 - simply multiply with the factor between them.
444 *
445 * But first make sure the multiplication result cannot
446 * overflow:
447 */
448 if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
449 return MAX_JIFFY_OFFSET;
450
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800451 return m * (HZ / MSEC_PER_SEC);
452#else
Ingo Molnar41cf5442007-02-16 01:27:28 -0800453 /*
454 * Generic case - multiply, round and divide. But first
455 * check that if we are doing a net multiplication, that
456 * we wouldnt overflow:
457 */
458 if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
459 return MAX_JIFFY_OFFSET;
460
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800461 return (m * HZ + MSEC_PER_SEC - 1) / MSEC_PER_SEC;
462#endif
463}
464EXPORT_SYMBOL(msecs_to_jiffies);
465
466unsigned long usecs_to_jiffies(const unsigned int u)
467{
468 if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET))
469 return MAX_JIFFY_OFFSET;
470#if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ)
471 return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ);
472#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
473 return u * (HZ / USEC_PER_SEC);
474#else
475 return (u * HZ + USEC_PER_SEC - 1) / USEC_PER_SEC;
476#endif
477}
478EXPORT_SYMBOL(usecs_to_jiffies);
479
480/*
481 * The TICK_NSEC - 1 rounds up the value to the next resolution. Note
482 * that a remainder subtract here would not do the right thing as the
483 * resolution values don't fall on second boundries. I.e. the line:
484 * nsec -= nsec % TICK_NSEC; is NOT a correct resolution rounding.
485 *
486 * Rather, we just shift the bits off the right.
487 *
488 * The >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) converts the scaled nsec
489 * value to a scaled second value.
490 */
491unsigned long
492timespec_to_jiffies(const struct timespec *value)
493{
494 unsigned long sec = value->tv_sec;
495 long nsec = value->tv_nsec + TICK_NSEC - 1;
496
497 if (sec >= MAX_SEC_IN_JIFFIES){
498 sec = MAX_SEC_IN_JIFFIES;
499 nsec = 0;
500 }
501 return (((u64)sec * SEC_CONVERSION) +
502 (((u64)nsec * NSEC_CONVERSION) >>
503 (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
504
505}
506EXPORT_SYMBOL(timespec_to_jiffies);
507
508void
509jiffies_to_timespec(const unsigned long jiffies, struct timespec *value)
510{
511 /*
512 * Convert jiffies to nanoseconds and separate with
513 * one divide.
514 */
515 u64 nsec = (u64)jiffies * TICK_NSEC;
516 value->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &value->tv_nsec);
517}
518EXPORT_SYMBOL(jiffies_to_timespec);
519
520/* Same for "timeval"
521 *
522 * Well, almost. The problem here is that the real system resolution is
523 * in nanoseconds and the value being converted is in micro seconds.
524 * Also for some machines (those that use HZ = 1024, in-particular),
525 * there is a LARGE error in the tick size in microseconds.
526
527 * The solution we use is to do the rounding AFTER we convert the
528 * microsecond part. Thus the USEC_ROUND, the bits to be shifted off.
529 * Instruction wise, this should cost only an additional add with carry
530 * instruction above the way it was done above.
531 */
532unsigned long
533timeval_to_jiffies(const struct timeval *value)
534{
535 unsigned long sec = value->tv_sec;
536 long usec = value->tv_usec;
537
538 if (sec >= MAX_SEC_IN_JIFFIES){
539 sec = MAX_SEC_IN_JIFFIES;
540 usec = 0;
541 }
542 return (((u64)sec * SEC_CONVERSION) +
543 (((u64)usec * USEC_CONVERSION + USEC_ROUND) >>
544 (USEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
545}
Thomas Bittermann456a09d2007-04-04 22:20:54 +0200546EXPORT_SYMBOL(timeval_to_jiffies);
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800547
548void jiffies_to_timeval(const unsigned long jiffies, struct timeval *value)
549{
550 /*
551 * Convert jiffies to nanoseconds and separate with
552 * one divide.
553 */
554 u64 nsec = (u64)jiffies * TICK_NSEC;
555 long tv_usec;
556
557 value->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &tv_usec);
558 tv_usec /= NSEC_PER_USEC;
559 value->tv_usec = tv_usec;
560}
Thomas Bittermann456a09d2007-04-04 22:20:54 +0200561EXPORT_SYMBOL(jiffies_to_timeval);
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800562
563/*
564 * Convert jiffies/jiffies_64 to clock_t and back.
565 */
566clock_t jiffies_to_clock_t(long x)
567{
568#if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
David Fries6ffc7872008-02-06 01:38:04 -0800569# if HZ < USER_HZ
570 return x * (USER_HZ / HZ);
571# else
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800572 return x / (HZ / USER_HZ);
David Fries6ffc7872008-02-06 01:38:04 -0800573# endif
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800574#else
575 u64 tmp = (u64)x * TICK_NSEC;
576 do_div(tmp, (NSEC_PER_SEC / USER_HZ));
577 return (long)tmp;
578#endif
579}
580EXPORT_SYMBOL(jiffies_to_clock_t);
581
582unsigned long clock_t_to_jiffies(unsigned long x)
583{
584#if (HZ % USER_HZ)==0
585 if (x >= ~0UL / (HZ / USER_HZ))
586 return ~0UL;
587 return x * (HZ / USER_HZ);
588#else
589 u64 jif;
590
591 /* Don't worry about loss of precision here .. */
592 if (x >= ~0UL / HZ * USER_HZ)
593 return ~0UL;
594
595 /* .. but do try to contain it here */
596 jif = x * (u64) HZ;
597 do_div(jif, USER_HZ);
598 return jif;
599#endif
600}
601EXPORT_SYMBOL(clock_t_to_jiffies);
602
603u64 jiffies_64_to_clock_t(u64 x)
604{
605#if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
David Fries6ffc7872008-02-06 01:38:04 -0800606# if HZ < USER_HZ
607 x *= USER_HZ;
608 do_div(x, HZ);
Andrew Mortonec03d702008-02-06 01:38:06 -0800609# elif HZ > USER_HZ
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800610 do_div(x, HZ / USER_HZ);
Andrew Mortonec03d702008-02-06 01:38:06 -0800611# else
612 /* Nothing to do */
David Fries6ffc7872008-02-06 01:38:04 -0800613# endif
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800614#else
615 /*
616 * There are better ways that don't overflow early,
617 * but even this doesn't overflow in hundreds of years
618 * in 64 bits, so..
619 */
620 x *= TICK_NSEC;
621 do_div(x, (NSEC_PER_SEC / USER_HZ));
622#endif
623 return x;
624}
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800625EXPORT_SYMBOL(jiffies_64_to_clock_t);
626
627u64 nsec_to_clock_t(u64 x)
628{
629#if (NSEC_PER_SEC % USER_HZ) == 0
630 do_div(x, (NSEC_PER_SEC / USER_HZ));
631#elif (USER_HZ % 512) == 0
632 x *= USER_HZ/512;
633 do_div(x, (NSEC_PER_SEC / 512));
634#else
635 /*
636 * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024,
637 * overflow after 64.99 years.
638 * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ...
639 */
640 x *= 9;
641 do_div(x, (unsigned long)((9ull * NSEC_PER_SEC + (USER_HZ/2)) /
642 USER_HZ));
643#endif
644 return x;
645}
646
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647#if (BITS_PER_LONG < 64)
648u64 get_jiffies_64(void)
649{
650 unsigned long seq;
651 u64 ret;
652
653 do {
654 seq = read_seqbegin(&xtime_lock);
655 ret = jiffies_64;
656 } while (read_seqretry(&xtime_lock, seq));
657 return ret;
658}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659EXPORT_SYMBOL(get_jiffies_64);
660#endif
661
662EXPORT_SYMBOL(jiffies);