3 * Common time routines among all ppc machines.
5 * Written by Cort Dougan (cort@cs.nmt.edu) to merge
6 * Paul Mackerras' version and mine for PReP and Pmac.
7 * MPC8xx/MBX changes by Dan Malek (dmalek@jlc.net).
8 * Converted for 64-bit by Mike Corrigan (mikejc@us.ibm.com)
10 * First round of bugfixes by Gabriel Paubert (paubert@iram.es)
11 * to make clock more stable (2.4.0-test5). The only thing
12 * that this code assumes is that the timebases have been synchronized
13 * by firmware on SMP and are never stopped (never do sleep
14 * on SMP then, nap and doze are OK).
16 * Speeded up do_gettimeofday by getting rid of references to
17 * xtime (which required locks for consistency). (mikejc@us.ibm.com)
19 * TODO (not necessarily in this file):
20 * - improve precision and reproducibility of timebase frequency
21 * measurement at boot time. (for iSeries, we calibrate the timebase
22 * against the Titan chip's clock.)
23 * - for astronomical applications: add a new function to get
24 * non ambiguous timestamps even around leap seconds. This needs
25 * a new timestamp format and a good name.
27 * 1997-09-10 Updated NTP code according to technical memorandum Jan '96
28 * "A Kernel Model for Precision Timekeeping" by Dave Mills
30 * This program is free software; you can redistribute it and/or
31 * modify it under the terms of the GNU General Public License
32 * as published by the Free Software Foundation; either version
33 * 2 of the License, or (at your option) any later version.
36 #include <linux/config.h>
37 #include <linux/errno.h>
38 #include <linux/module.h>
39 #include <linux/sched.h>
40 #include <linux/kernel.h>
41 #include <linux/param.h>
42 #include <linux/string.h>
44 #include <linux/interrupt.h>
45 #include <linux/timex.h>
46 #include <linux/kernel_stat.h>
47 #include <linux/mc146818rtc.h>
48 #include <linux/time.h>
49 #include <linux/init.h>
50 #include <linux/profile.h>
51 #include <linux/cpu.h>
53 #include <asm/segment.h>
55 #include <asm/processor.h>
56 #include <asm/nvram.h>
57 #include <asm/cache.h>
58 #include <asm/machdep.h>
59 #ifdef CONFIG_PPC_ISERIES
60 #include <asm/iSeries/ItLpQueue.h>
61 #include <asm/iSeries/HvCallXm.h>
63 #include <asm/uaccess.h>
65 #include <asm/ppcdebug.h>
67 #include <asm/sections.h>
69 void smp_local_timer_interrupt(struct pt_regs *);
71 u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
73 EXPORT_SYMBOL(jiffies_64);
75 /* keep track of when we need to update the rtc */
76 time_t last_rtc_update;
77 extern int piranha_simulator;
78 #ifdef CONFIG_PPC_ISERIES
79 unsigned long iSeries_recal_titan = 0;
80 unsigned long iSeries_recal_tb = 0;
81 static unsigned long first_settimeofday = 1;
84 #define XSEC_PER_SEC (1024*1024)
86 unsigned long tb_ticks_per_jiffy;
87 unsigned long tb_ticks_per_usec = 100; /* sane default */
88 unsigned long tb_ticks_per_sec;
89 unsigned long next_xtime_sync_tb;
90 unsigned long xtime_sync_interval;
91 unsigned long tb_to_xs;
93 unsigned long processor_freq;
94 spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED;
96 unsigned long tb_to_ns_scale;
97 unsigned long tb_to_ns_shift;
99 struct gettimeofday_struct do_gtod;
101 extern unsigned long wall_jiffies;
102 extern unsigned long lpevent_count;
103 extern int smp_tb_synchronized;
105 extern struct timezone sys_tz;
107 void ppc_adjtimex(void);
109 static unsigned adjusting_time = 0;
111 static __inline__ void timer_check_rtc(void)
114 * update the rtc when needed, this should be performed on the
115 * right fraction of a second. Half or full second ?
116 * Full second works on mk48t59 clocks, others need testing.
117 * Note that this update is basically only used through
118 * the adjtimex system calls. Setting the HW clock in
119 * any other way is a /dev/rtc and userland business.
120 * This is still wrong by -0.5/+1.5 jiffies because of the
121 * timer interrupt resolution and possible delay, but here we
122 * hit a quantization limit which can only be solved by higher
123 * resolution timers and decoupling time management from timer
124 * interrupts. This is also wrong on the clocks
125 * which require being written at the half second boundary.
126 * We should have an rtc call that only sets the minutes and
127 * seconds like on Intel to avoid problems with non UTC clocks.
129 if ( (time_status & STA_UNSYNC) == 0 &&
130 xtime.tv_sec - last_rtc_update >= 659 &&
131 abs((xtime.tv_nsec/1000) - (1000000-1000000/HZ)) < 500000/HZ &&
132 jiffies - wall_jiffies == 1) {
134 to_tm(xtime.tv_sec+1, &tm);
137 if (ppc_md.set_rtc_time(&tm) == 0)
138 last_rtc_update = xtime.tv_sec+1;
140 /* Try again one minute later */
141 last_rtc_update += 60;
145 /* Synchronize xtime with do_gettimeofday */
147 static __inline__ void timer_sync_xtime( unsigned long cur_tb )
149 struct timeval my_tv;
151 if ( cur_tb > next_xtime_sync_tb ) {
152 next_xtime_sync_tb = cur_tb + xtime_sync_interval;
153 do_gettimeofday( &my_tv );
154 if ( xtime.tv_sec <= my_tv.tv_sec ) {
155 xtime.tv_sec = my_tv.tv_sec;
156 xtime.tv_nsec = my_tv.tv_usec * 1000;
162 unsigned long profile_pc(struct pt_regs *regs)
164 unsigned long pc = instruction_pointer(regs);
166 if (in_lock_functions(pc))
171 EXPORT_SYMBOL(profile_pc);
174 #ifdef CONFIG_PPC_ISERIES
177 * This function recalibrates the timebase based on the 49-bit time-of-day
178 * value in the Titan chip. The Titan is much more accurate than the value
179 * returned by the service processor for the timebase frequency.
182 static void iSeries_tb_recal(void)
184 struct div_result divres;
185 unsigned long titan, tb;
187 titan = HvCallXm_loadTod();
188 if ( iSeries_recal_titan ) {
189 unsigned long tb_ticks = tb - iSeries_recal_tb;
190 unsigned long titan_usec = (titan - iSeries_recal_titan) >> 12;
191 unsigned long new_tb_ticks_per_sec = (tb_ticks * USEC_PER_SEC)/titan_usec;
192 unsigned long new_tb_ticks_per_jiffy = (new_tb_ticks_per_sec+(HZ/2))/HZ;
193 long tick_diff = new_tb_ticks_per_jiffy - tb_ticks_per_jiffy;
195 /* make sure tb_ticks_per_sec and tb_ticks_per_jiffy are consistent */
196 new_tb_ticks_per_sec = new_tb_ticks_per_jiffy * HZ;
198 if ( tick_diff < 0 ) {
199 tick_diff = -tick_diff;
203 if ( tick_diff < tb_ticks_per_jiffy/25 ) {
204 printk( "Titan recalibrate: new tb_ticks_per_jiffy = %lu (%c%ld)\n",
205 new_tb_ticks_per_jiffy, sign, tick_diff );
206 tb_ticks_per_jiffy = new_tb_ticks_per_jiffy;
207 tb_ticks_per_sec = new_tb_ticks_per_sec;
208 div128_by_32( XSEC_PER_SEC, 0, tb_ticks_per_sec, &divres );
209 do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
210 tb_to_xs = divres.result_low;
211 do_gtod.varp->tb_to_xs = tb_to_xs;
212 systemcfg->tb_ticks_per_sec = tb_ticks_per_sec;
213 systemcfg->tb_to_xs = tb_to_xs;
216 printk( "Titan recalibrate: FAILED (difference > 4 percent)\n"
217 " new tb_ticks_per_jiffy = %lu\n"
218 " old tb_ticks_per_jiffy = %lu\n",
219 new_tb_ticks_per_jiffy, tb_ticks_per_jiffy );
223 iSeries_recal_titan = titan;
224 iSeries_recal_tb = tb;
229 * For iSeries shared processors, we have to let the hypervisor
230 * set the hardware decrementer. We set a virtual decrementer
231 * in the ItLpPaca and call the hypervisor if the virtual
232 * decrementer is less than the current value in the hardware
233 * decrementer. (almost always the new decrementer value will
234 * be greater than the current hardware decementer so the hypervisor
235 * call will not be needed)
238 unsigned long tb_last_stamp __cacheline_aligned_in_smp;
241 * timer_interrupt - gets called when the decrementer overflows,
242 * with interrupts disabled.
244 int timer_interrupt(struct pt_regs * regs)
247 unsigned long cur_tb;
248 struct paca_struct *lpaca = get_paca();
249 unsigned long cpu = smp_processor_id();
253 #ifndef CONFIG_PPC_ISERIES
254 profile_tick(CPU_PROFILING, regs);
257 lpaca->lppaca.xIntDword.xFields.xDecrInt = 0;
259 while (lpaca->next_jiffy_update_tb <= (cur_tb = get_tb())) {
263 * We cannot disable the decrementer, so in the period
264 * between this cpu's being marked offline in cpu_online_map
265 * and calling stop-self, it is taking timer interrupts.
266 * Avoid calling into the scheduler rebalancing code if this
269 if (!cpu_is_offline(cpu))
270 smp_local_timer_interrupt(regs);
273 * No need to check whether cpu is offline here; boot_cpuid
274 * should have been fixed up by now.
276 if (cpu == boot_cpuid) {
277 write_seqlock(&xtime_lock);
278 tb_last_stamp = lpaca->next_jiffy_update_tb;
280 timer_sync_xtime( cur_tb );
282 write_sequnlock(&xtime_lock);
283 if ( adjusting_time && (time_adjust == 0) )
286 lpaca->next_jiffy_update_tb += tb_ticks_per_jiffy;
289 next_dec = lpaca->next_jiffy_update_tb - cur_tb;
290 if (next_dec > lpaca->default_decr)
291 next_dec = lpaca->default_decr;
294 #ifdef CONFIG_PPC_ISERIES
296 struct ItLpQueue *lpq = lpaca->lpqueue_ptr;
297 if (lpq && ItLpQueue_isLpIntPending(lpq))
298 lpevent_count += ItLpQueue_process(lpq, regs);
308 * Scheduler clock - returns current time in nanosec units.
310 * Note: mulhdu(a, b) (multiply high double unsigned) returns
311 * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
312 * are 64-bit unsigned numbers.
314 unsigned long long sched_clock(void)
316 return mulhdu(get_tb(), tb_to_ns_scale) << tb_to_ns_shift;
320 * This version of gettimeofday has microsecond resolution.
322 void do_gettimeofday(struct timeval *tv)
324 unsigned long sec, usec, tb_ticks;
325 unsigned long xsec, tb_xsec;
326 struct gettimeofday_vars * temp_varp;
327 unsigned long temp_tb_to_xs, temp_stamp_xsec;
329 /* These calculations are faster (gets rid of divides)
330 * if done in units of 1/2^20 rather than microseconds.
331 * The conversion to microseconds at the end is done
332 * without a divide (and in fact, without a multiply) */
333 tb_ticks = get_tb() - do_gtod.tb_orig_stamp;
334 temp_varp = do_gtod.varp;
335 temp_tb_to_xs = temp_varp->tb_to_xs;
336 temp_stamp_xsec = temp_varp->stamp_xsec;
337 tb_xsec = mulhdu( tb_ticks, temp_tb_to_xs );
338 xsec = temp_stamp_xsec + tb_xsec;
339 sec = xsec / XSEC_PER_SEC;
340 xsec -= sec * XSEC_PER_SEC;
341 usec = (xsec * USEC_PER_SEC)/XSEC_PER_SEC;
347 EXPORT_SYMBOL(do_gettimeofday);
349 int do_settimeofday(struct timespec *tv)
351 time_t wtm_sec, new_sec = tv->tv_sec;
352 long wtm_nsec, new_nsec = tv->tv_nsec;
354 unsigned long delta_xsec;
356 unsigned long new_xsec;
358 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
361 write_seqlock_irqsave(&xtime_lock, flags);
362 /* Updating the RTC is not the job of this code. If the time is
363 * stepped under NTP, the RTC will be update after STA_UNSYNC
364 * is cleared. Tool like clock/hwclock either copy the RTC
365 * to the system time, in which case there is no point in writing
366 * to the RTC again, or write to the RTC but then they don't call
367 * settimeofday to perform this operation.
369 #ifdef CONFIG_PPC_ISERIES
370 if ( first_settimeofday ) {
372 first_settimeofday = 0;
375 tb_delta = tb_ticks_since(tb_last_stamp);
376 tb_delta += (jiffies - wall_jiffies) * tb_ticks_per_jiffy;
378 new_nsec -= tb_delta / tb_ticks_per_usec / 1000;
380 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - new_sec);
381 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - new_nsec);
383 set_normalized_timespec(&xtime, new_sec, new_nsec);
384 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
386 /* In case of a large backwards jump in time with NTP, we want the
387 * clock to be updated as soon as the PLL is again in lock.
389 last_rtc_update = new_sec - 658;
391 time_adjust = 0; /* stop active adjtime() */
392 time_status |= STA_UNSYNC;
393 time_maxerror = NTP_PHASE_LIMIT;
394 time_esterror = NTP_PHASE_LIMIT;
396 delta_xsec = mulhdu( (tb_last_stamp-do_gtod.tb_orig_stamp), do_gtod.varp->tb_to_xs );
397 new_xsec = (new_nsec * XSEC_PER_SEC) / NSEC_PER_SEC;
398 new_xsec += new_sec * XSEC_PER_SEC;
399 if ( new_xsec > delta_xsec ) {
400 do_gtod.varp->stamp_xsec = new_xsec - delta_xsec;
401 systemcfg->stamp_xsec = new_xsec - delta_xsec;
404 /* This is only for the case where the user is setting the time
405 * way back to a time such that the boot time would have been
406 * before 1970 ... eg. we booted ten days ago, and we are setting
407 * the time to Jan 5, 1970 */
408 do_gtod.varp->stamp_xsec = new_xsec;
409 do_gtod.tb_orig_stamp = tb_last_stamp;
410 systemcfg->stamp_xsec = new_xsec;
411 systemcfg->tb_orig_stamp = tb_last_stamp;
414 systemcfg->tz_minuteswest = sys_tz.tz_minuteswest;
415 systemcfg->tz_dsttime = sys_tz.tz_dsttime;
417 write_sequnlock_irqrestore(&xtime_lock, flags);
422 EXPORT_SYMBOL(do_settimeofday);
425 * This function is a copy of the architecture independent function
426 * but which calls do_settimeofday rather than setting the xtime
427 * fields itself. This way, the fields which are used for
428 * do_settimeofday get updated too.
430 long ppc64_sys32_stime(int __user * tptr)
433 struct timespec myTimeval;
435 if (!capable(CAP_SYS_TIME))
438 if (get_user(value, tptr))
441 myTimeval.tv_sec = value;
442 myTimeval.tv_nsec = 0;
444 do_settimeofday(&myTimeval);
450 * This function is a copy of the architecture independent function
451 * but which calls do_settimeofday rather than setting the xtime
452 * fields itself. This way, the fields which are used for
453 * do_settimeofday get updated too.
455 long ppc64_sys_stime(long __user * tptr)
458 struct timespec myTimeval;
460 if (!capable(CAP_SYS_TIME))
463 if (get_user(value, tptr))
466 myTimeval.tv_sec = value;
467 myTimeval.tv_nsec = 0;
469 do_settimeofday(&myTimeval);
474 void __init time_init(void)
476 /* This function is only called on the boot processor */
479 struct div_result res;
480 unsigned long scale, shift;
482 ppc_md.calibrate_decr();
485 * Compute scale factor for sched_clock.
486 * The calibrate_decr() function has set tb_ticks_per_sec,
487 * which is the timebase frequency.
488 * We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
489 * the 128-bit result as a 64.64 fixed-point number.
490 * We then shift that number right until it is less than 1.0,
491 * giving us the scale factor and shift count to use in
494 div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
495 scale = res.result_low;
496 for (shift = 0; res.result_high != 0; ++shift) {
497 scale = (scale >> 1) | (res.result_high << 63);
498 res.result_high >>= 1;
500 tb_to_ns_scale = scale;
501 tb_to_ns_shift = shift;
503 #ifdef CONFIG_PPC_ISERIES
504 if (!piranha_simulator)
506 ppc_md.get_boot_time(&tm);
508 write_seqlock_irqsave(&xtime_lock, flags);
509 xtime.tv_sec = mktime(tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
510 tm.tm_hour, tm.tm_min, tm.tm_sec);
511 tb_last_stamp = get_tb();
512 do_gtod.tb_orig_stamp = tb_last_stamp;
513 do_gtod.varp = &do_gtod.vars[0];
515 do_gtod.varp->stamp_xsec = xtime.tv_sec * XSEC_PER_SEC;
516 do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
517 do_gtod.varp->tb_to_xs = tb_to_xs;
518 do_gtod.tb_to_us = tb_to_us;
519 systemcfg->tb_orig_stamp = tb_last_stamp;
520 systemcfg->tb_update_count = 0;
521 systemcfg->tb_ticks_per_sec = tb_ticks_per_sec;
522 systemcfg->stamp_xsec = xtime.tv_sec * XSEC_PER_SEC;
523 systemcfg->tb_to_xs = tb_to_xs;
525 xtime_sync_interval = tb_ticks_per_sec - (tb_ticks_per_sec/8);
526 next_xtime_sync_tb = tb_last_stamp + xtime_sync_interval;
531 last_rtc_update = xtime.tv_sec;
532 set_normalized_timespec(&wall_to_monotonic,
533 -xtime.tv_sec, -xtime.tv_nsec);
534 write_sequnlock_irqrestore(&xtime_lock, flags);
536 /* Not exact, but the timer interrupt takes care of this */
537 set_dec(tb_ticks_per_jiffy);
541 * After adjtimex is called, adjust the conversion of tb ticks
542 * to microseconds to keep do_gettimeofday synchronized
545 * Use the time_adjust, time_freq and time_offset computed by adjtimex to
546 * adjust the frequency.
549 /* #define DEBUG_PPC_ADJTIMEX 1 */
551 void ppc_adjtimex(void)
553 unsigned long den, new_tb_ticks_per_sec, tb_ticks, old_xsec, new_tb_to_xs, new_xsec, new_stamp_xsec;
554 unsigned long tb_ticks_per_sec_delta;
555 long delta_freq, ltemp;
556 struct div_result divres;
558 struct gettimeofday_vars * temp_varp;
560 long singleshot_ppm = 0;
562 /* Compute parts per million frequency adjustment to accomplish the time adjustment
563 implied by time_offset to be applied over the elapsed time indicated by time_constant.
564 Use SHIFT_USEC to get it into the same units as time_freq. */
565 if ( time_offset < 0 ) {
566 ltemp = -time_offset;
567 ltemp <<= SHIFT_USEC - SHIFT_UPDATE;
568 ltemp >>= SHIFT_KG + time_constant;
573 ltemp <<= SHIFT_USEC - SHIFT_UPDATE;
574 ltemp >>= SHIFT_KG + time_constant;
577 /* If there is a single shot time adjustment in progress */
579 #ifdef DEBUG_PPC_ADJTIMEX
580 printk("ppc_adjtimex: ");
581 if ( adjusting_time == 0 )
583 printk("single shot time_adjust = %ld\n", time_adjust);
588 /* Compute parts per million frequency adjustment to match time_adjust */
589 singleshot_ppm = tickadj * HZ;
591 * The adjustment should be tickadj*HZ to match the code in
592 * linux/kernel/timer.c, but experiments show that this is too
593 * large. 3/4 of tickadj*HZ seems about right
595 singleshot_ppm -= singleshot_ppm / 4;
596 /* Use SHIFT_USEC to get it into the same units as time_freq */
597 singleshot_ppm <<= SHIFT_USEC;
598 if ( time_adjust < 0 )
599 singleshot_ppm = -singleshot_ppm;
602 #ifdef DEBUG_PPC_ADJTIMEX
603 if ( adjusting_time )
604 printk("ppc_adjtimex: ending single shot time_adjust\n");
609 /* Add up all of the frequency adjustments */
610 delta_freq = time_freq + ltemp + singleshot_ppm;
612 /* Compute a new value for tb_ticks_per_sec based on the frequency adjustment */
613 den = 1000000 * (1 << (SHIFT_USEC - 8));
614 if ( delta_freq < 0 ) {
615 tb_ticks_per_sec_delta = ( tb_ticks_per_sec * ( (-delta_freq) >> (SHIFT_USEC - 8))) / den;
616 new_tb_ticks_per_sec = tb_ticks_per_sec + tb_ticks_per_sec_delta;
619 tb_ticks_per_sec_delta = ( tb_ticks_per_sec * ( delta_freq >> (SHIFT_USEC - 8))) / den;
620 new_tb_ticks_per_sec = tb_ticks_per_sec - tb_ticks_per_sec_delta;
623 #ifdef DEBUG_PPC_ADJTIMEX
624 printk("ppc_adjtimex: ltemp = %ld, time_freq = %ld, singleshot_ppm = %ld\n", ltemp, time_freq, singleshot_ppm);
625 printk("ppc_adjtimex: tb_ticks_per_sec - base = %ld new = %ld\n", tb_ticks_per_sec, new_tb_ticks_per_sec);
628 /* Compute a new value of tb_to_xs (used to convert tb to microseconds and a new value of
629 stamp_xsec which is the time (in 1/2^20 second units) corresponding to tb_orig_stamp. This
630 new value of stamp_xsec compensates for the change in frequency (implied by the new tb_to_xs)
631 which guarantees that the current time remains the same */
632 tb_ticks = get_tb() - do_gtod.tb_orig_stamp;
633 div128_by_32( 1024*1024, 0, new_tb_ticks_per_sec, &divres );
634 new_tb_to_xs = divres.result_low;
635 new_xsec = mulhdu( tb_ticks, new_tb_to_xs );
637 write_seqlock_irqsave( &xtime_lock, flags );
638 old_xsec = mulhdu( tb_ticks, do_gtod.varp->tb_to_xs );
639 new_stamp_xsec = do_gtod.varp->stamp_xsec + old_xsec - new_xsec;
641 /* There are two copies of tb_to_xs and stamp_xsec so that no lock is needed to access and use these
642 values in do_gettimeofday. We alternate the copies and as long as a reasonable time elapses between
643 changes, there will never be inconsistent values. ntpd has a minimum of one minute between updates */
645 if (do_gtod.var_idx == 0) {
646 temp_varp = &do_gtod.vars[1];
650 temp_varp = &do_gtod.vars[0];
653 temp_varp->tb_to_xs = new_tb_to_xs;
654 temp_varp->stamp_xsec = new_stamp_xsec;
656 do_gtod.varp = temp_varp;
657 do_gtod.var_idx = temp_idx;
660 * tb_update_count is used to allow the problem state gettimeofday code
661 * to assure itself that it sees a consistent view of the tb_to_xs and
662 * stamp_xsec variables. It reads the tb_update_count, then reads
663 * tb_to_xs and stamp_xsec and then reads tb_update_count again. If
664 * the two values of tb_update_count match and are even then the
665 * tb_to_xs and stamp_xsec values are consistent. If not, then it
666 * loops back and reads them again until this criteria is met.
668 ++(systemcfg->tb_update_count);
670 systemcfg->tb_to_xs = new_tb_to_xs;
671 systemcfg->stamp_xsec = new_stamp_xsec;
673 ++(systemcfg->tb_update_count);
675 write_sequnlock_irqrestore( &xtime_lock, flags );
680 #define TICK_SIZE tick
682 #define STARTOFTIME 1970
683 #define SECDAY 86400L
684 #define SECYR (SECDAY * 365)
685 #define leapyear(year) ((year) % 4 == 0)
686 #define days_in_year(a) (leapyear(a) ? 366 : 365)
687 #define days_in_month(a) (month_days[(a) - 1])
689 static int month_days[12] = {
690 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
694 * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
696 void GregorianDay(struct rtc_time * tm)
701 int MonthOffset[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
703 lastYear=tm->tm_year-1;
706 * Number of leap corrections to apply up to end of last year
708 leapsToDate = lastYear/4 - lastYear/100 + lastYear/400;
711 * This year is a leap year if it is divisible by 4 except when it is
712 * divisible by 100 unless it is divisible by 400
714 * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 will be
716 if((tm->tm_year%4==0) &&
717 ((tm->tm_year%100!=0) || (tm->tm_year%400==0)) &&
721 * We are past Feb. 29 in a leap year
730 day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] +
736 void to_tm(int tim, struct rtc_time * tm)
739 register long hms, day;
744 /* Hours, minutes, seconds are easy */
745 tm->tm_hour = hms / 3600;
746 tm->tm_min = (hms % 3600) / 60;
747 tm->tm_sec = (hms % 3600) % 60;
749 /* Number of years in days */
750 for (i = STARTOFTIME; day >= days_in_year(i); i++)
751 day -= days_in_year(i);
754 /* Number of months in days left */
755 if (leapyear(tm->tm_year))
756 days_in_month(FEBRUARY) = 29;
757 for (i = 1; day >= days_in_month(i); i++)
758 day -= days_in_month(i);
759 days_in_month(FEBRUARY) = 28;
762 /* Days are what is left over (+1) from all that. */
763 tm->tm_mday = day + 1;
766 * Determine the day of week
771 /* Auxiliary function to compute scaling factors */
772 /* Actually the choice of a timebase running at 1/4 the of the bus
773 * frequency giving resolution of a few tens of nanoseconds is quite nice.
774 * It makes this computation very precise (27-28 bits typically) which
775 * is optimistic considering the stability of most processor clock
776 * oscillators and the precision with which the timebase frequency
777 * is measured but does not harm.
779 unsigned mulhwu_scale_factor(unsigned inscale, unsigned outscale) {
780 unsigned mlt=0, tmp, err;
781 /* No concern for performance, it's done once: use a stupid
782 * but safe and compact method to find the multiplier.
785 for (tmp = 1U<<31; tmp != 0; tmp >>= 1) {
786 if (mulhwu(inscale, mlt|tmp) < outscale) mlt|=tmp;
789 /* We might still be off by 1 for the best approximation.
790 * A side effect of this is that if outscale is too large
791 * the returned value will be zero.
792 * Many corner cases have been checked and seem to work,
793 * some might have been forgotten in the test however.
796 err = inscale*(mlt+1);
797 if (err <= inscale/2) mlt++;
802 * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
806 void div128_by_32( unsigned long dividend_high, unsigned long dividend_low,
807 unsigned divisor, struct div_result *dr )
809 unsigned long a,b,c,d, w,x,y,z, ra,rb,rc;
811 a = dividend_high >> 32;
812 b = dividend_high & 0xffffffff;
813 c = dividend_low >> 32;
814 d = dividend_low & 0xffffffff;
817 ra = (a - (w * divisor)) << 32;
819 x = (ra + b)/divisor;
820 rb = ((ra + b) - (x * divisor)) << 32;
822 y = (rb + c)/divisor;
823 rc = ((rb + b) - (y * divisor)) << 32;
825 z = (rc + d)/divisor;
827 dr->result_high = (w << 32) + x;
828 dr->result_low = (y << 32) + z;