blob: ffe19149d77006cb6c22db392b0a828962c655d3 [file] [log] [blame]
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
12 *
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
28 */
29
30#include <linux/module.h>
31#include <linux/timex.h>
Randy.Dunlapc59ede72006-01-11 12:17:46 -080032#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070033#include <linux/errno.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070034#include <linux/syscalls.h>
35#include <linux/security.h>
36#include <linux/fs.h>
37#include <linux/module.h>
38
39#include <asm/uaccess.h>
40#include <asm/unistd.h>
41
42/*
43 * 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 Molnar4e44f342007-07-15 23:41:18 -070060 /*
61 * We read xtime.tv_sec atomically - it's updated
62 * atomically by update_wall_time(), so no need to
63 * even read-lock the xtime seqlock:
64 */
65 time_t i = xtime.tv_sec;
Linus Torvalds1da177e2005-04-16 15:20:36 -070066
Ingo Molnar4e44f342007-07-15 23:41:18 -070067 smp_rmb(); /* sys_time() results are coherent */
Linus Torvalds1da177e2005-04-16 15:20:36 -070068
69 if (tloc) {
Ingo Molnar4e44f342007-07-15 23:41:18 -070070 if (put_user(i, tloc))
Linus Torvalds1da177e2005-04-16 15:20:36 -070071 i = -EFAULT;
72 }
73 return i;
74}
75
76/*
77 * sys_stime() can be implemented in user-level using
78 * sys_settimeofday(). Is this for backwards compatibility? If so,
79 * why not move it into the appropriate arch directory (for those
80 * architectures that need it).
81 */
82
83asmlinkage long sys_stime(time_t __user *tptr)
84{
85 struct timespec tv;
86 int err;
87
88 if (get_user(tv.tv_sec, tptr))
89 return -EFAULT;
90
91 tv.tv_nsec = 0;
92
93 err = security_settime(&tv, NULL);
94 if (err)
95 return err;
96
97 do_settimeofday(&tv);
98 return 0;
99}
100
101#endif /* __ARCH_WANT_SYS_TIME */
102
103asmlinkage long sys_gettimeofday(struct timeval __user *tv, struct timezone __user *tz)
104{
105 if (likely(tv != NULL)) {
106 struct timeval ktv;
107 do_gettimeofday(&ktv);
108 if (copy_to_user(tv, &ktv, sizeof(ktv)))
109 return -EFAULT;
110 }
111 if (unlikely(tz != NULL)) {
112 if (copy_to_user(tz, &sys_tz, sizeof(sys_tz)))
113 return -EFAULT;
114 }
115 return 0;
116}
117
118/*
119 * Adjust the time obtained from the CMOS to be UTC time instead of
120 * local time.
121 *
122 * This is ugly, but preferable to the alternatives. Otherwise we
123 * would either need to write a program to do it in /etc/rc (and risk
124 * confusion if the program gets run more than once; it would also be
125 * hard to make the program warp the clock precisely n hours) or
126 * compile in the timezone information into the kernel. Bad, bad....
127 *
128 * - TYT, 1992-01-01
129 *
130 * The best thing to do is to keep the CMOS clock in universal time (UTC)
131 * as real UNIX machines always do it. This avoids all headaches about
132 * daylight saving times and warping kernel clocks.
133 */
Jesper Juhl77933d72005-07-27 11:46:09 -0700134static inline void warp_clock(void)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700135{
136 write_seqlock_irq(&xtime_lock);
137 wall_to_monotonic.tv_sec -= sys_tz.tz_minuteswest * 60;
138 xtime.tv_sec += sys_tz.tz_minuteswest * 60;
139 time_interpolator_reset();
140 write_sequnlock_irq(&xtime_lock);
141 clock_was_set();
142}
143
144/*
145 * In case for some reason the CMOS clock has not already been running
146 * in UTC, but in some local time: The first time we set the timezone,
147 * we will warp the clock so that it is ticking UTC time instead of
148 * local time. Presumably, if someone is setting the timezone then we
149 * are running in an environment where the programs understand about
150 * timezones. This should be done at boot time in the /etc/rc script,
151 * as soon as possible, so that the clock can be set right. Otherwise,
152 * various programs will get confused when the clock gets warped.
153 */
154
155int do_sys_settimeofday(struct timespec *tv, struct timezone *tz)
156{
157 static int firsttime = 1;
158 int error = 0;
159
Linus Torvalds951069e2006-01-31 10:16:55 -0800160 if (tv && !timespec_valid(tv))
Thomas Gleixner718bcce2006-01-09 20:52:29 -0800161 return -EINVAL;
162
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 error = security_settime(tv, tz);
164 if (error)
165 return error;
166
167 if (tz) {
168 /* SMP safe, global irq locking makes it work. */
169 sys_tz = *tz;
170 if (firsttime) {
171 firsttime = 0;
172 if (!tv)
173 warp_clock();
174 }
175 }
176 if (tv)
177 {
178 /* SMP safe, again the code in arch/foo/time.c should
179 * globally block out interrupts when it runs.
180 */
181 return do_settimeofday(tv);
182 }
183 return 0;
184}
185
186asmlinkage long sys_settimeofday(struct timeval __user *tv,
187 struct timezone __user *tz)
188{
189 struct timeval user_tv;
190 struct timespec new_ts;
191 struct timezone new_tz;
192
193 if (tv) {
194 if (copy_from_user(&user_tv, tv, sizeof(*tv)))
195 return -EFAULT;
196 new_ts.tv_sec = user_tv.tv_sec;
197 new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
198 }
199 if (tz) {
200 if (copy_from_user(&new_tz, tz, sizeof(*tz)))
201 return -EFAULT;
202 }
203
204 return do_sys_settimeofday(tv ? &new_ts : NULL, tz ? &new_tz : NULL);
205}
206
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207asmlinkage long sys_adjtimex(struct timex __user *txc_p)
208{
209 struct timex txc; /* Local copy of parameter */
210 int ret;
211
212 /* Copy the user data space into the kernel copy
213 * structure. But bear in mind that the structures
214 * may change
215 */
216 if(copy_from_user(&txc, txc_p, sizeof(struct timex)))
217 return -EFAULT;
218 ret = do_adjtimex(&txc);
219 return copy_to_user(txc_p, &txc, sizeof(struct timex)) ? -EFAULT : ret;
220}
221
222inline struct timespec current_kernel_time(void)
223{
224 struct timespec now;
225 unsigned long seq;
226
227 do {
228 seq = read_seqbegin(&xtime_lock);
229
230 now = xtime;
231 } while (read_seqretry(&xtime_lock, seq));
232
233 return now;
234}
235
236EXPORT_SYMBOL(current_kernel_time);
237
238/**
239 * current_fs_time - Return FS time
240 * @sb: Superblock.
241 *
Kalin KOZHUHAROV8ba8e952006-04-01 01:41:22 +0200242 * Return the current time truncated to the time granularity supported by
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243 * the fs.
244 */
245struct timespec current_fs_time(struct super_block *sb)
246{
247 struct timespec now = current_kernel_time();
248 return timespec_trunc(now, sb->s_time_gran);
249}
250EXPORT_SYMBOL(current_fs_time);
251
Eric Dumazet753e9c52007-05-08 00:25:32 -0700252/*
253 * Convert jiffies to milliseconds and back.
254 *
255 * Avoid unnecessary multiplications/divisions in the
256 * two most common HZ cases:
257 */
258unsigned int inline jiffies_to_msecs(const unsigned long j)
259{
260#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
261 return (MSEC_PER_SEC / HZ) * j;
262#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
263 return (j + (HZ / MSEC_PER_SEC) - 1)/(HZ / MSEC_PER_SEC);
264#else
265 return (j * MSEC_PER_SEC) / HZ;
266#endif
267}
268EXPORT_SYMBOL(jiffies_to_msecs);
269
270unsigned int inline jiffies_to_usecs(const unsigned long j)
271{
272#if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ)
273 return (USEC_PER_SEC / HZ) * j;
274#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
275 return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC);
276#else
277 return (j * USEC_PER_SEC) / HZ;
278#endif
279}
280EXPORT_SYMBOL(jiffies_to_usecs);
281
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282/**
Kalin KOZHUHAROV8ba8e952006-04-01 01:41:22 +0200283 * timespec_trunc - Truncate timespec to a granularity
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 * @t: Timespec
Kalin KOZHUHAROV8ba8e952006-04-01 01:41:22 +0200285 * @gran: Granularity in ns.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700286 *
Kalin KOZHUHAROV8ba8e952006-04-01 01:41:22 +0200287 * Truncate a timespec to a granularity. gran must be smaller than a second.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288 * Always rounds down.
289 *
290 * This function should be only used for timestamps returned by
291 * current_kernel_time() or CURRENT_TIME, not with do_gettimeofday() because
292 * it doesn't handle the better resolution of the later.
293 */
294struct timespec timespec_trunc(struct timespec t, unsigned gran)
295{
296 /*
297 * Division is pretty slow so avoid it for common cases.
298 * Currently current_kernel_time() never returns better than
299 * jiffies resolution. Exploit that.
300 */
301 if (gran <= jiffies_to_usecs(1) * 1000) {
302 /* nothing */
303 } else if (gran == 1000000000) {
304 t.tv_nsec = 0;
305 } else {
306 t.tv_nsec -= t.tv_nsec % gran;
307 }
308 return t;
309}
310EXPORT_SYMBOL(timespec_trunc);
311
312#ifdef CONFIG_TIME_INTERPOLATION
313void getnstimeofday (struct timespec *tv)
314{
315 unsigned long seq,sec,nsec;
316
317 do {
318 seq = read_seqbegin(&xtime_lock);
319 sec = xtime.tv_sec;
320 nsec = xtime.tv_nsec+time_interpolator_get_offset();
321 } while (unlikely(read_seqretry(&xtime_lock, seq)));
322
323 while (unlikely(nsec >= NSEC_PER_SEC)) {
324 nsec -= NSEC_PER_SEC;
325 ++sec;
326 }
327 tv->tv_sec = sec;
328 tv->tv_nsec = nsec;
329}
330EXPORT_SYMBOL_GPL(getnstimeofday);
331
332int do_settimeofday (struct timespec *tv)
333{
334 time_t wtm_sec, sec = tv->tv_sec;
335 long wtm_nsec, nsec = tv->tv_nsec;
336
337 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
338 return -EINVAL;
339
340 write_seqlock_irq(&xtime_lock);
341 {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
343 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
344
345 set_normalized_timespec(&xtime, sec, nsec);
346 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
347
348 time_adjust = 0; /* stop active adjtime() */
349 time_status |= STA_UNSYNC;
350 time_maxerror = NTP_PHASE_LIMIT;
351 time_esterror = NTP_PHASE_LIMIT;
352 time_interpolator_reset();
353 }
354 write_sequnlock_irq(&xtime_lock);
355 clock_was_set();
356 return 0;
357}
Al Viro943eae02005-10-29 07:32:07 +0100358EXPORT_SYMBOL(do_settimeofday);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359
360void do_gettimeofday (struct timeval *tv)
361{
362 unsigned long seq, nsec, usec, sec, offset;
363 do {
364 seq = read_seqbegin(&xtime_lock);
365 offset = time_interpolator_get_offset();
366 sec = xtime.tv_sec;
367 nsec = xtime.tv_nsec;
368 } while (unlikely(read_seqretry(&xtime_lock, seq)));
369
370 usec = (nsec + offset) / 1000;
371
372 while (unlikely(usec >= USEC_PER_SEC)) {
373 usec -= USEC_PER_SEC;
374 ++sec;
375 }
376
377 tv->tv_sec = sec;
378 tv->tv_usec = usec;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379
Ingo Molnar4e44f342007-07-15 23:41:18 -0700380 /*
381 * Make sure xtime.tv_sec [returned by sys_time()] always
382 * follows the gettimeofday() result precisely. This
383 * condition is extremely unlikely, it can hit at most
384 * once per second:
385 */
386 if (unlikely(xtime.tv_sec != tv->tv_sec)) {
387 unsigned long flags;
388
389 write_seqlock_irqsave(&xtime_lock, flags);
390 update_wall_time();
391 write_sequnlock_irqrestore(&xtime_lock, flags);
392 }
393}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700394EXPORT_SYMBOL(do_gettimeofday);
395
Ingo Molnar4e44f342007-07-15 23:41:18 -0700396#else /* CONFIG_TIME_INTERPOLATION */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397
john stultzcf3c7692006-06-26 00:25:08 -0700398#ifndef CONFIG_GENERIC_TIME
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399/*
400 * Simulate gettimeofday using do_gettimeofday which only allows a timeval
401 * and therefore only yields usec accuracy
402 */
403void getnstimeofday(struct timespec *tv)
404{
405 struct timeval x;
406
407 do_gettimeofday(&x);
408 tv->tv_sec = x.tv_sec;
409 tv->tv_nsec = x.tv_usec * NSEC_PER_USEC;
410}
Takashi Iwaic6ecf7e2005-10-14 15:59:03 -0700411EXPORT_SYMBOL_GPL(getnstimeofday);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412#endif
Ingo Molnar4e44f342007-07-15 23:41:18 -0700413#endif /* CONFIG_TIME_INTERPOLATION */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414
Thomas Gleixner753be622006-01-09 20:52:22 -0800415/* Converts Gregorian date to seconds since 1970-01-01 00:00:00.
416 * Assumes input in normal date format, i.e. 1980-12-31 23:59:59
417 * => year=1980, mon=12, day=31, hour=23, min=59, sec=59.
418 *
419 * [For the Julian calendar (which was used in Russia before 1917,
420 * Britain & colonies before 1752, anywhere else before 1582,
421 * and is still in use by some communities) leave out the
422 * -year/100+year/400 terms, and add 10.]
423 *
424 * This algorithm was first published by Gauss (I think).
425 *
426 * WARNING: this function will overflow on 2106-02-07 06:28:16 on
427 * machines were long is 32-bit! (However, as time_t is signed, we
428 * will already get problems at other places on 2038-01-19 03:14:08)
429 */
430unsigned long
Ingo Molnarf4818902006-01-09 20:52:23 -0800431mktime(const unsigned int year0, const unsigned int mon0,
432 const unsigned int day, const unsigned int hour,
433 const unsigned int min, const unsigned int sec)
Thomas Gleixner753be622006-01-09 20:52:22 -0800434{
Ingo Molnarf4818902006-01-09 20:52:23 -0800435 unsigned int mon = mon0, year = year0;
436
437 /* 1..12 -> 11,12,1..10 */
438 if (0 >= (int) (mon -= 2)) {
439 mon += 12; /* Puts Feb last since it has leap day */
Thomas Gleixner753be622006-01-09 20:52:22 -0800440 year -= 1;
441 }
442
443 return ((((unsigned long)
444 (year/4 - year/100 + year/400 + 367*mon/12 + day) +
445 year*365 - 719499
446 )*24 + hour /* now have hours */
447 )*60 + min /* now have minutes */
448 )*60 + sec; /* finally seconds */
449}
450
Andrew Morton199e7052006-01-09 20:52:24 -0800451EXPORT_SYMBOL(mktime);
452
Thomas Gleixner753be622006-01-09 20:52:22 -0800453/**
454 * set_normalized_timespec - set timespec sec and nsec parts and normalize
455 *
456 * @ts: pointer to timespec variable to be set
457 * @sec: seconds to set
458 * @nsec: nanoseconds to set
459 *
460 * Set seconds and nanoseconds field of a timespec variable and
461 * normalize to the timespec storage format
462 *
463 * Note: The tv_nsec part is always in the range of
464 * 0 <= tv_nsec < NSEC_PER_SEC
465 * For negative values only the tv_sec field is negative !
466 */
Ingo Molnarf4818902006-01-09 20:52:23 -0800467void set_normalized_timespec(struct timespec *ts, time_t sec, long nsec)
Thomas Gleixner753be622006-01-09 20:52:22 -0800468{
469 while (nsec >= NSEC_PER_SEC) {
470 nsec -= NSEC_PER_SEC;
471 ++sec;
472 }
473 while (nsec < 0) {
474 nsec += NSEC_PER_SEC;
475 --sec;
476 }
477 ts->tv_sec = sec;
478 ts->tv_nsec = nsec;
479}
480
Thomas Gleixnerf8f46da2006-01-09 20:52:30 -0800481/**
482 * ns_to_timespec - Convert nanoseconds to timespec
483 * @nsec: the nanoseconds value to be converted
484 *
485 * Returns the timespec representation of the nsec parameter.
486 */
Roman Zippeldf869b62006-03-26 01:38:11 -0800487struct timespec ns_to_timespec(const s64 nsec)
Thomas Gleixnerf8f46da2006-01-09 20:52:30 -0800488{
489 struct timespec ts;
490
George Anzinger88fc3892006-02-03 03:04:20 -0800491 if (!nsec)
492 return (struct timespec) {0, 0};
493
494 ts.tv_sec = div_long_long_rem_signed(nsec, NSEC_PER_SEC, &ts.tv_nsec);
495 if (unlikely(nsec < 0))
496 set_normalized_timespec(&ts, ts.tv_sec, ts.tv_nsec);
Thomas Gleixnerf8f46da2006-01-09 20:52:30 -0800497
498 return ts;
499}
Stephen Hemminger85795d62007-03-24 21:35:33 -0700500EXPORT_SYMBOL(ns_to_timespec);
Thomas Gleixnerf8f46da2006-01-09 20:52:30 -0800501
502/**
503 * ns_to_timeval - Convert nanoseconds to timeval
504 * @nsec: the nanoseconds value to be converted
505 *
506 * Returns the timeval representation of the nsec parameter.
507 */
Roman Zippeldf869b62006-03-26 01:38:11 -0800508struct timeval ns_to_timeval(const s64 nsec)
Thomas Gleixnerf8f46da2006-01-09 20:52:30 -0800509{
510 struct timespec ts = ns_to_timespec(nsec);
511 struct timeval tv;
512
513 tv.tv_sec = ts.tv_sec;
514 tv.tv_usec = (suseconds_t) ts.tv_nsec / 1000;
515
516 return tv;
517}
Eric Dumazetb7aa0bf2007-04-19 16:16:32 -0700518EXPORT_SYMBOL(ns_to_timeval);
Thomas Gleixnerf8f46da2006-01-09 20:52:30 -0800519
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800520/*
Ingo Molnar41cf5442007-02-16 01:27:28 -0800521 * When we convert to jiffies then we interpret incoming values
522 * the following way:
523 *
524 * - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)
525 *
526 * - 'too large' values [that would result in larger than
527 * MAX_JIFFY_OFFSET values] mean 'infinite timeout' too.
528 *
529 * - all other values are converted to jiffies by either multiplying
530 * the input value by a factor or dividing it with a factor
531 *
532 * We must also be careful about 32-bit overflows.
533 */
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800534unsigned long msecs_to_jiffies(const unsigned int m)
535{
Ingo Molnar41cf5442007-02-16 01:27:28 -0800536 /*
537 * Negative value, means infinite timeout:
538 */
539 if ((int)m < 0)
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800540 return MAX_JIFFY_OFFSET;
Ingo Molnar41cf5442007-02-16 01:27:28 -0800541
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800542#if HZ <= MSEC_PER_SEC && !(MSEC_PER_SEC % HZ)
Ingo Molnar41cf5442007-02-16 01:27:28 -0800543 /*
544 * HZ is equal to or smaller than 1000, and 1000 is a nice
545 * round multiple of HZ, divide with the factor between them,
546 * but round upwards:
547 */
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800548 return (m + (MSEC_PER_SEC / HZ) - 1) / (MSEC_PER_SEC / HZ);
549#elif HZ > MSEC_PER_SEC && !(HZ % MSEC_PER_SEC)
Ingo Molnar41cf5442007-02-16 01:27:28 -0800550 /*
551 * HZ is larger than 1000, and HZ is a nice round multiple of
552 * 1000 - simply multiply with the factor between them.
553 *
554 * But first make sure the multiplication result cannot
555 * overflow:
556 */
557 if (m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
558 return MAX_JIFFY_OFFSET;
559
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800560 return m * (HZ / MSEC_PER_SEC);
561#else
Ingo Molnar41cf5442007-02-16 01:27:28 -0800562 /*
563 * Generic case - multiply, round and divide. But first
564 * check that if we are doing a net multiplication, that
565 * we wouldnt overflow:
566 */
567 if (HZ > MSEC_PER_SEC && m > jiffies_to_msecs(MAX_JIFFY_OFFSET))
568 return MAX_JIFFY_OFFSET;
569
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800570 return (m * HZ + MSEC_PER_SEC - 1) / MSEC_PER_SEC;
571#endif
572}
573EXPORT_SYMBOL(msecs_to_jiffies);
574
575unsigned long usecs_to_jiffies(const unsigned int u)
576{
577 if (u > jiffies_to_usecs(MAX_JIFFY_OFFSET))
578 return MAX_JIFFY_OFFSET;
579#if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ)
580 return (u + (USEC_PER_SEC / HZ) - 1) / (USEC_PER_SEC / HZ);
581#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
582 return u * (HZ / USEC_PER_SEC);
583#else
584 return (u * HZ + USEC_PER_SEC - 1) / USEC_PER_SEC;
585#endif
586}
587EXPORT_SYMBOL(usecs_to_jiffies);
588
589/*
590 * The TICK_NSEC - 1 rounds up the value to the next resolution. Note
591 * that a remainder subtract here would not do the right thing as the
592 * resolution values don't fall on second boundries. I.e. the line:
593 * nsec -= nsec % TICK_NSEC; is NOT a correct resolution rounding.
594 *
595 * Rather, we just shift the bits off the right.
596 *
597 * The >> (NSEC_JIFFIE_SC - SEC_JIFFIE_SC) converts the scaled nsec
598 * value to a scaled second value.
599 */
600unsigned long
601timespec_to_jiffies(const struct timespec *value)
602{
603 unsigned long sec = value->tv_sec;
604 long nsec = value->tv_nsec + TICK_NSEC - 1;
605
606 if (sec >= MAX_SEC_IN_JIFFIES){
607 sec = MAX_SEC_IN_JIFFIES;
608 nsec = 0;
609 }
610 return (((u64)sec * SEC_CONVERSION) +
611 (((u64)nsec * NSEC_CONVERSION) >>
612 (NSEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
613
614}
615EXPORT_SYMBOL(timespec_to_jiffies);
616
617void
618jiffies_to_timespec(const unsigned long jiffies, struct timespec *value)
619{
620 /*
621 * Convert jiffies to nanoseconds and separate with
622 * one divide.
623 */
624 u64 nsec = (u64)jiffies * TICK_NSEC;
625 value->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &value->tv_nsec);
626}
627EXPORT_SYMBOL(jiffies_to_timespec);
628
629/* Same for "timeval"
630 *
631 * Well, almost. The problem here is that the real system resolution is
632 * in nanoseconds and the value being converted is in micro seconds.
633 * Also for some machines (those that use HZ = 1024, in-particular),
634 * there is a LARGE error in the tick size in microseconds.
635
636 * The solution we use is to do the rounding AFTER we convert the
637 * microsecond part. Thus the USEC_ROUND, the bits to be shifted off.
638 * Instruction wise, this should cost only an additional add with carry
639 * instruction above the way it was done above.
640 */
641unsigned long
642timeval_to_jiffies(const struct timeval *value)
643{
644 unsigned long sec = value->tv_sec;
645 long usec = value->tv_usec;
646
647 if (sec >= MAX_SEC_IN_JIFFIES){
648 sec = MAX_SEC_IN_JIFFIES;
649 usec = 0;
650 }
651 return (((u64)sec * SEC_CONVERSION) +
652 (((u64)usec * USEC_CONVERSION + USEC_ROUND) >>
653 (USEC_JIFFIE_SC - SEC_JIFFIE_SC))) >> SEC_JIFFIE_SC;
654}
Thomas Bittermann456a09d2007-04-04 22:20:54 +0200655EXPORT_SYMBOL(timeval_to_jiffies);
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800656
657void jiffies_to_timeval(const unsigned long jiffies, struct timeval *value)
658{
659 /*
660 * Convert jiffies to nanoseconds and separate with
661 * one divide.
662 */
663 u64 nsec = (u64)jiffies * TICK_NSEC;
664 long tv_usec;
665
666 value->tv_sec = div_long_long_rem(nsec, NSEC_PER_SEC, &tv_usec);
667 tv_usec /= NSEC_PER_USEC;
668 value->tv_usec = tv_usec;
669}
Thomas Bittermann456a09d2007-04-04 22:20:54 +0200670EXPORT_SYMBOL(jiffies_to_timeval);
Ingo Molnar8b9365d2007-02-16 01:27:27 -0800671
672/*
673 * Convert jiffies/jiffies_64 to clock_t and back.
674 */
675clock_t jiffies_to_clock_t(long x)
676{
677#if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
678 return x / (HZ / USER_HZ);
679#else
680 u64 tmp = (u64)x * TICK_NSEC;
681 do_div(tmp, (NSEC_PER_SEC / USER_HZ));
682 return (long)tmp;
683#endif
684}
685EXPORT_SYMBOL(jiffies_to_clock_t);
686
687unsigned long clock_t_to_jiffies(unsigned long x)
688{
689#if (HZ % USER_HZ)==0
690 if (x >= ~0UL / (HZ / USER_HZ))
691 return ~0UL;
692 return x * (HZ / USER_HZ);
693#else
694 u64 jif;
695
696 /* Don't worry about loss of precision here .. */
697 if (x >= ~0UL / HZ * USER_HZ)
698 return ~0UL;
699
700 /* .. but do try to contain it here */
701 jif = x * (u64) HZ;
702 do_div(jif, USER_HZ);
703 return jif;
704#endif
705}
706EXPORT_SYMBOL(clock_t_to_jiffies);
707
708u64 jiffies_64_to_clock_t(u64 x)
709{
710#if (TICK_NSEC % (NSEC_PER_SEC / USER_HZ)) == 0
711 do_div(x, HZ / USER_HZ);
712#else
713 /*
714 * There are better ways that don't overflow early,
715 * but even this doesn't overflow in hundreds of years
716 * in 64 bits, so..
717 */
718 x *= TICK_NSEC;
719 do_div(x, (NSEC_PER_SEC / USER_HZ));
720#endif
721 return x;
722}
723
724EXPORT_SYMBOL(jiffies_64_to_clock_t);
725
726u64 nsec_to_clock_t(u64 x)
727{
728#if (NSEC_PER_SEC % USER_HZ) == 0
729 do_div(x, (NSEC_PER_SEC / USER_HZ));
730#elif (USER_HZ % 512) == 0
731 x *= USER_HZ/512;
732 do_div(x, (NSEC_PER_SEC / 512));
733#else
734 /*
735 * max relative error 5.7e-8 (1.8s per year) for USER_HZ <= 1024,
736 * overflow after 64.99 years.
737 * exact for HZ=60, 72, 90, 120, 144, 180, 300, 600, 900, ...
738 */
739 x *= 9;
740 do_div(x, (unsigned long)((9ull * NSEC_PER_SEC + (USER_HZ/2)) /
741 USER_HZ));
742#endif
743 return x;
744}
745
Linus Torvalds1da177e2005-04-16 15:20:36 -0700746#if (BITS_PER_LONG < 64)
747u64 get_jiffies_64(void)
748{
749 unsigned long seq;
750 u64 ret;
751
752 do {
753 seq = read_seqbegin(&xtime_lock);
754 ret = jiffies_64;
755 } while (read_seqretry(&xtime_lock, seq));
756 return ret;
757}
758
759EXPORT_SYMBOL(get_jiffies_64);
760#endif
761
762EXPORT_SYMBOL(jiffies);