2 * Common time routines among all ppc machines.
4 * Written by Cort Dougan (cort@cs.nmt.edu) to merge
5 * Paul Mackerras' version and mine for PReP and Pmac.
6 * MPC8xx/MBX changes by Dan Malek (dmalek@jlc.net).
7 * Converted for 64-bit by Mike Corrigan (mikejc@us.ibm.com)
9 * First round of bugfixes by Gabriel Paubert (paubert@iram.es)
10 * to make clock more stable (2.4.0-test5). The only thing
11 * that this code assumes is that the timebases have been synchronized
12 * by firmware on SMP and are never stopped (never do sleep
13 * on SMP then, nap and doze are OK).
15 * Speeded up do_gettimeofday by getting rid of references to
16 * xtime (which required locks for consistency). (mikejc@us.ibm.com)
18 * TODO (not necessarily in this file):
19 * - improve precision and reproducibility of timebase frequency
20 * measurement at boot time. (for iSeries, we calibrate the timebase
21 * against the Titan chip's clock.)
22 * - for astronomical applications: add a new function to get
23 * non ambiguous timestamps even around leap seconds. This needs
24 * a new timestamp format and a good name.
26 * 1997-09-10 Updated NTP code according to technical memorandum Jan '96
27 * "A Kernel Model for Precision Timekeeping" by Dave Mills
29 * This program is free software; you can redistribute it and/or
30 * modify it under the terms of the GNU General Public License
31 * as published by the Free Software Foundation; either version
32 * 2 of the License, or (at your option) any later version.
35 #include <linux/config.h>
36 #include <linux/errno.h>
37 #include <linux/module.h>
38 #include <linux/sched.h>
39 #include <linux/kernel.h>
40 #include <linux/param.h>
41 #include <linux/string.h>
43 #include <linux/interrupt.h>
44 #include <linux/timex.h>
45 #include <linux/kernel_stat.h>
46 #include <linux/time.h>
47 #include <linux/init.h>
48 #include <linux/profile.h>
49 #include <linux/cpu.h>
50 #include <linux/security.h>
51 #include <linux/percpu.h>
52 #include <linux/rtc.h>
55 #include <asm/processor.h>
56 #include <asm/nvram.h>
57 #include <asm/cache.h>
58 #include <asm/machdep.h>
59 #include <asm/uaccess.h>
63 #include <asm/div64.h>
65 #include <asm/systemcfg.h>
66 #include <asm/firmware.h>
68 #ifdef CONFIG_PPC_ISERIES
69 #include <asm/iSeries/ItLpQueue.h>
70 #include <asm/iSeries/HvCallXm.h>
73 u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
75 EXPORT_SYMBOL(jiffies_64);
77 /* keep track of when we need to update the rtc */
78 time_t last_rtc_update;
79 extern int piranha_simulator;
80 #ifdef CONFIG_PPC_ISERIES
81 unsigned long iSeries_recal_titan = 0;
82 unsigned long iSeries_recal_tb = 0;
83 static unsigned long first_settimeofday = 1;
86 /* The decrementer counts down by 128 every 128ns on a 601. */
87 #define DECREMENTER_COUNT_601 (1000000000 / HZ)
89 #define XSEC_PER_SEC (1024*1024)
92 #define SCALE_XSEC(xsec, max) (((xsec) * max) / XSEC_PER_SEC)
94 /* compute ((xsec << 12) * max) >> 32 */
95 #define SCALE_XSEC(xsec, max) mulhwu((xsec) << 12, max)
98 unsigned long tb_ticks_per_jiffy;
99 unsigned long tb_ticks_per_usec = 100; /* sane default */
100 EXPORT_SYMBOL(tb_ticks_per_usec);
101 unsigned long tb_ticks_per_sec;
104 unsigned long processor_freq;
105 DEFINE_SPINLOCK(rtc_lock);
106 EXPORT_SYMBOL_GPL(rtc_lock);
109 unsigned tb_to_ns_shift;
111 struct gettimeofday_struct do_gtod;
113 extern unsigned long wall_jiffies;
115 extern struct timezone sys_tz;
116 static long timezone_offset;
118 void ppc_adjtimex(void);
120 static unsigned adjusting_time = 0;
122 unsigned long ppc_proc_freq;
123 unsigned long ppc_tb_freq;
125 #ifdef CONFIG_PPC32 /* XXX for now */
129 static __inline__ void timer_check_rtc(void)
132 * update the rtc when needed, this should be performed on the
133 * right fraction of a second. Half or full second ?
134 * Full second works on mk48t59 clocks, others need testing.
135 * Note that this update is basically only used through
136 * the adjtimex system calls. Setting the HW clock in
137 * any other way is a /dev/rtc and userland business.
138 * This is still wrong by -0.5/+1.5 jiffies because of the
139 * timer interrupt resolution and possible delay, but here we
140 * hit a quantization limit which can only be solved by higher
141 * resolution timers and decoupling time management from timer
142 * interrupts. This is also wrong on the clocks
143 * which require being written at the half second boundary.
144 * We should have an rtc call that only sets the minutes and
145 * seconds like on Intel to avoid problems with non UTC clocks.
148 xtime.tv_sec - last_rtc_update >= 659 &&
149 abs((xtime.tv_nsec/1000) - (1000000-1000000/HZ)) < 500000/HZ &&
150 jiffies - wall_jiffies == 1) {
152 to_tm(xtime.tv_sec + 1 + timezone_offset, &tm);
155 if (ppc_md.set_rtc_time(&tm) == 0)
156 last_rtc_update = xtime.tv_sec + 1;
158 /* Try again one minute later */
159 last_rtc_update += 60;
164 * This version of gettimeofday has microsecond resolution.
166 static inline void __do_gettimeofday(struct timeval *tv, u64 tb_val)
168 unsigned long sec, usec;
170 struct gettimeofday_vars *temp_varp;
171 u64 temp_tb_to_xs, temp_stamp_xsec;
174 * These calculations are faster (gets rid of divides)
175 * if done in units of 1/2^20 rather than microseconds.
176 * The conversion to microseconds at the end is done
177 * without a divide (and in fact, without a multiply)
179 temp_varp = do_gtod.varp;
180 tb_ticks = tb_val - temp_varp->tb_orig_stamp;
181 temp_tb_to_xs = temp_varp->tb_to_xs;
182 temp_stamp_xsec = temp_varp->stamp_xsec;
183 xsec = temp_stamp_xsec + mulhdu(tb_ticks, temp_tb_to_xs);
184 sec = xsec / XSEC_PER_SEC;
185 usec = (unsigned long)xsec & (XSEC_PER_SEC - 1);
186 usec = SCALE_XSEC(usec, 1000000);
192 void do_gettimeofday(struct timeval *tv)
194 __do_gettimeofday(tv, get_tb());
197 EXPORT_SYMBOL(do_gettimeofday);
199 /* Synchronize xtime with do_gettimeofday */
201 static inline void timer_sync_xtime(unsigned long cur_tb)
204 /* why do we do this? */
205 struct timeval my_tv;
207 __do_gettimeofday(&my_tv, cur_tb);
209 if (xtime.tv_sec <= my_tv.tv_sec) {
210 xtime.tv_sec = my_tv.tv_sec;
211 xtime.tv_nsec = my_tv.tv_usec * 1000;
217 * There are two copies of tb_to_xs and stamp_xsec so that no
218 * lock is needed to access and use these values in
219 * do_gettimeofday. We alternate the copies and as long as a
220 * reasonable time elapses between changes, there will never
221 * be inconsistent values. ntpd has a minimum of one minute
224 static inline void update_gtod(u64 new_tb_stamp, u64 new_stamp_xsec,
225 unsigned int new_tb_to_xs)
228 struct gettimeofday_vars *temp_varp;
230 temp_idx = (do_gtod.var_idx == 0);
231 temp_varp = &do_gtod.vars[temp_idx];
233 temp_varp->tb_to_xs = new_tb_to_xs;
234 temp_varp->tb_orig_stamp = new_tb_stamp;
235 temp_varp->stamp_xsec = new_stamp_xsec;
237 do_gtod.varp = temp_varp;
238 do_gtod.var_idx = temp_idx;
242 * tb_update_count is used to allow the userspace gettimeofday code
243 * to assure itself that it sees a consistent view of the tb_to_xs and
244 * stamp_xsec variables. It reads the tb_update_count, then reads
245 * tb_to_xs and stamp_xsec and then reads tb_update_count again. If
246 * the two values of tb_update_count match and are even then the
247 * tb_to_xs and stamp_xsec values are consistent. If not, then it
248 * loops back and reads them again until this criteria is met.
250 ++(systemcfg->tb_update_count);
252 systemcfg->tb_orig_stamp = new_tb_stamp;
253 systemcfg->stamp_xsec = new_stamp_xsec;
254 systemcfg->tb_to_xs = new_tb_to_xs;
256 ++(systemcfg->tb_update_count);
261 * When the timebase - tb_orig_stamp gets too big, we do a manipulation
262 * between tb_orig_stamp and stamp_xsec. The goal here is to keep the
263 * difference tb - tb_orig_stamp small enough to always fit inside a
264 * 32 bits number. This is a requirement of our fast 32 bits userland
265 * implementation in the vdso. If we "miss" a call to this function
266 * (interrupt latency, CPU locked in a spinlock, ...) and we end up
267 * with a too big difference, then the vdso will fallback to calling
270 static __inline__ void timer_recalc_offset(u64 cur_tb)
272 unsigned long offset;
275 offset = cur_tb - do_gtod.varp->tb_orig_stamp;
276 if ((offset & 0x80000000u) == 0)
278 new_stamp_xsec = do_gtod.varp->stamp_xsec
279 + mulhdu(offset, do_gtod.varp->tb_to_xs);
280 update_gtod(cur_tb, new_stamp_xsec, do_gtod.varp->tb_to_xs);
284 unsigned long profile_pc(struct pt_regs *regs)
286 unsigned long pc = instruction_pointer(regs);
288 if (in_lock_functions(pc))
293 EXPORT_SYMBOL(profile_pc);
296 #ifdef CONFIG_PPC_ISERIES
299 * This function recalibrates the timebase based on the 49-bit time-of-day
300 * value in the Titan chip. The Titan is much more accurate than the value
301 * returned by the service processor for the timebase frequency.
304 static void iSeries_tb_recal(void)
306 struct div_result divres;
307 unsigned long titan, tb;
309 titan = HvCallXm_loadTod();
310 if ( iSeries_recal_titan ) {
311 unsigned long tb_ticks = tb - iSeries_recal_tb;
312 unsigned long titan_usec = (titan - iSeries_recal_titan) >> 12;
313 unsigned long new_tb_ticks_per_sec = (tb_ticks * USEC_PER_SEC)/titan_usec;
314 unsigned long new_tb_ticks_per_jiffy = (new_tb_ticks_per_sec+(HZ/2))/HZ;
315 long tick_diff = new_tb_ticks_per_jiffy - tb_ticks_per_jiffy;
317 /* make sure tb_ticks_per_sec and tb_ticks_per_jiffy are consistent */
318 new_tb_ticks_per_sec = new_tb_ticks_per_jiffy * HZ;
320 if ( tick_diff < 0 ) {
321 tick_diff = -tick_diff;
325 if ( tick_diff < tb_ticks_per_jiffy/25 ) {
326 printk( "Titan recalibrate: new tb_ticks_per_jiffy = %lu (%c%ld)\n",
327 new_tb_ticks_per_jiffy, sign, tick_diff );
328 tb_ticks_per_jiffy = new_tb_ticks_per_jiffy;
329 tb_ticks_per_sec = new_tb_ticks_per_sec;
330 div128_by_32( XSEC_PER_SEC, 0, tb_ticks_per_sec, &divres );
331 do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
332 tb_to_xs = divres.result_low;
333 do_gtod.varp->tb_to_xs = tb_to_xs;
334 systemcfg->tb_ticks_per_sec = tb_ticks_per_sec;
335 systemcfg->tb_to_xs = tb_to_xs;
338 printk( "Titan recalibrate: FAILED (difference > 4 percent)\n"
339 " new tb_ticks_per_jiffy = %lu\n"
340 " old tb_ticks_per_jiffy = %lu\n",
341 new_tb_ticks_per_jiffy, tb_ticks_per_jiffy );
345 iSeries_recal_titan = titan;
346 iSeries_recal_tb = tb;
351 * For iSeries shared processors, we have to let the hypervisor
352 * set the hardware decrementer. We set a virtual decrementer
353 * in the lppaca and call the hypervisor if the virtual
354 * decrementer is less than the current value in the hardware
355 * decrementer. (almost always the new decrementer value will
356 * be greater than the current hardware decementer so the hypervisor
357 * call will not be needed)
360 u64 tb_last_stamp __cacheline_aligned_in_smp;
363 * Note that on ppc32 this only stores the bottom 32 bits of
364 * the timebase value, but that's enough to tell when a jiffy
367 DEFINE_PER_CPU(unsigned long, last_jiffy);
370 * timer_interrupt - gets called when the decrementer overflows,
371 * with interrupts disabled.
373 void timer_interrupt(struct pt_regs * regs)
376 int cpu = smp_processor_id();
380 if (atomic_read(&ppc_n_lost_interrupts) != 0)
386 profile_tick(CPU_PROFILING, regs);
388 #ifdef CONFIG_PPC_ISERIES
389 get_paca()->lppaca.int_dword.fields.decr_int = 0;
392 while ((ticks = tb_ticks_since(per_cpu(last_jiffy, cpu)))
393 >= tb_ticks_per_jiffy) {
394 /* Update last_jiffy */
395 per_cpu(last_jiffy, cpu) += tb_ticks_per_jiffy;
396 /* Handle RTCL overflow on 601 */
397 if (__USE_RTC() && per_cpu(last_jiffy, cpu) >= 1000000000)
398 per_cpu(last_jiffy, cpu) -= 1000000000;
401 * We cannot disable the decrementer, so in the period
402 * between this cpu's being marked offline in cpu_online_map
403 * and calling stop-self, it is taking timer interrupts.
404 * Avoid calling into the scheduler rebalancing code if this
407 if (!cpu_is_offline(cpu))
408 update_process_times(user_mode(regs));
411 * No need to check whether cpu is offline here; boot_cpuid
412 * should have been fixed up by now.
414 if (cpu != boot_cpuid)
417 write_seqlock(&xtime_lock);
418 tb_last_stamp += tb_ticks_per_jiffy;
419 timer_recalc_offset(tb_last_stamp);
421 timer_sync_xtime(tb_last_stamp);
423 write_sequnlock(&xtime_lock);
424 if (adjusting_time && (time_adjust == 0))
428 next_dec = tb_ticks_per_jiffy - ticks;
431 #ifdef CONFIG_PPC_ISERIES
432 if (hvlpevent_is_pending())
433 process_hvlpevents(regs);
437 /* collect purr register values often, for accurate calculations */
438 if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
439 struct cpu_usage *cu = &__get_cpu_var(cpu_usage_array);
440 cu->current_tb = mfspr(SPRN_PURR);
447 void wakeup_decrementer(void)
451 set_dec(tb_ticks_per_jiffy);
453 * We don't expect this to be called on a machine with a 601,
454 * so using get_tbl is fine.
456 tb_last_stamp = get_tb();
458 per_cpu(last_jiffy, i) = tb_last_stamp;
462 void __init smp_space_timers(unsigned int max_cpus)
465 unsigned long offset = tb_ticks_per_jiffy / max_cpus;
466 unsigned long previous_tb = per_cpu(last_jiffy, boot_cpuid);
469 if (i != boot_cpuid) {
470 previous_tb += offset;
471 per_cpu(last_jiffy, i) = previous_tb;
478 * Scheduler clock - returns current time in nanosec units.
480 * Note: mulhdu(a, b) (multiply high double unsigned) returns
481 * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
482 * are 64-bit unsigned numbers.
484 unsigned long long sched_clock(void)
486 return mulhdu(get_tb(), tb_to_ns_scale) << tb_to_ns_shift;
489 int do_settimeofday(struct timespec *tv)
491 time_t wtm_sec, new_sec = tv->tv_sec;
492 long wtm_nsec, new_nsec = tv->tv_nsec;
497 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
500 write_seqlock_irqsave(&xtime_lock, flags);
503 * Updating the RTC is not the job of this code. If the time is
504 * stepped under NTP, the RTC will be updated after STA_UNSYNC
505 * is cleared. Tools like clock/hwclock either copy the RTC
506 * to the system time, in which case there is no point in writing
507 * to the RTC again, or write to the RTC but then they don't call
508 * settimeofday to perform this operation.
510 #ifdef CONFIG_PPC_ISERIES
511 if (first_settimeofday) {
513 first_settimeofday = 0;
516 tb_delta = tb_ticks_since(tb_last_stamp);
517 tb_delta += (jiffies - wall_jiffies) * tb_ticks_per_jiffy;
519 new_nsec -= 1000 * mulhwu(tb_to_us, tb_delta);
521 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - new_sec);
522 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - new_nsec);
524 set_normalized_timespec(&xtime, new_sec, new_nsec);
525 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
527 /* In case of a large backwards jump in time with NTP, we want the
528 * clock to be updated as soon as the PLL is again in lock.
530 last_rtc_update = new_sec - 658;
534 new_xsec = (u64)new_nsec * XSEC_PER_SEC;
535 do_div(new_xsec, NSEC_PER_SEC);
536 new_xsec += (u64)new_sec * XSEC_PER_SEC;
537 update_gtod(tb_last_stamp, new_xsec, do_gtod.varp->tb_to_xs);
540 systemcfg->tz_minuteswest = sys_tz.tz_minuteswest;
541 systemcfg->tz_dsttime = sys_tz.tz_dsttime;
544 write_sequnlock_irqrestore(&xtime_lock, flags);
549 EXPORT_SYMBOL(do_settimeofday);
551 #if defined(CONFIG_PPC_PSERIES) || defined(CONFIG_PPC_MAPLE) || defined(CONFIG_PPC_BPA) || defined(CONFIG_PPC_ISERIES)
552 void __init generic_calibrate_decr(void)
554 struct device_node *cpu;
555 struct div_result divres;
560 * The cpu node should have a timebase-frequency property
561 * to tell us the rate at which the decrementer counts.
563 cpu = of_find_node_by_type(NULL, "cpu");
565 ppc_tb_freq = DEFAULT_TB_FREQ; /* hardcoded default */
568 fp = (unsigned int *)get_property(cpu, "timebase-frequency",
576 printk(KERN_ERR "WARNING: Estimating decrementer frequency "
579 ppc_proc_freq = DEFAULT_PROC_FREQ;
582 fp = (unsigned int *)get_property(cpu, "clock-frequency",
590 printk(KERN_ERR "WARNING: Estimating processor frequency "
595 printk(KERN_INFO "time_init: decrementer frequency = %lu.%.6lu MHz\n",
596 ppc_tb_freq/1000000, ppc_tb_freq%1000000);
597 printk(KERN_INFO "time_init: processor frequency = %lu.%.6lu MHz\n",
598 ppc_proc_freq/1000000, ppc_proc_freq%1000000);
600 tb_ticks_per_jiffy = ppc_tb_freq / HZ;
601 tb_ticks_per_sec = tb_ticks_per_jiffy * HZ;
602 tb_ticks_per_usec = ppc_tb_freq / 1000000;
603 tb_to_us = mulhwu_scale_factor(ppc_tb_freq, 1000000);
604 div128_by_32(1024*1024, 0, tb_ticks_per_sec, &divres);
605 tb_to_xs = divres.result_low;
609 unsigned long get_boot_time(void)
613 if (ppc_md.get_boot_time)
614 return ppc_md.get_boot_time();
615 if (!ppc_md.get_rtc_time)
617 ppc_md.get_rtc_time(&tm);
618 return mktime(tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday,
619 tm.tm_hour, tm.tm_min, tm.tm_sec);
622 /* This function is only called on the boot processor */
623 void __init time_init(void)
626 unsigned long tm = 0;
627 struct div_result res;
631 if (ppc_md.time_init != NULL)
632 timezone_offset = ppc_md.time_init();
634 ppc_md.calibrate_decr();
637 get_paca()->default_decr = tb_ticks_per_jiffy;
641 * Compute scale factor for sched_clock.
642 * The calibrate_decr() function has set tb_ticks_per_sec,
643 * which is the timebase frequency.
644 * We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
645 * the 128-bit result as a 64.64 fixed-point number.
646 * We then shift that number right until it is less than 1.0,
647 * giving us the scale factor and shift count to use in
650 div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
651 scale = res.result_low;
652 for (shift = 0; res.result_high != 0; ++shift) {
653 scale = (scale >> 1) | (res.result_high << 63);
654 res.result_high >>= 1;
656 tb_to_ns_scale = scale;
657 tb_to_ns_shift = shift;
659 #ifdef CONFIG_PPC_ISERIES
660 if (!piranha_simulator)
662 tm = get_boot_time();
664 write_seqlock_irqsave(&xtime_lock, flags);
667 tb_last_stamp = get_tb();
668 do_gtod.varp = &do_gtod.vars[0];
670 do_gtod.varp->tb_orig_stamp = tb_last_stamp;
671 __get_cpu_var(last_jiffy) = tb_last_stamp;
672 do_gtod.varp->stamp_xsec = (u64) xtime.tv_sec * XSEC_PER_SEC;
673 do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
674 do_gtod.varp->tb_to_xs = tb_to_xs;
675 do_gtod.tb_to_us = tb_to_us;
677 systemcfg->tb_orig_stamp = tb_last_stamp;
678 systemcfg->tb_update_count = 0;
679 systemcfg->tb_ticks_per_sec = tb_ticks_per_sec;
680 systemcfg->stamp_xsec = xtime.tv_sec * XSEC_PER_SEC;
681 systemcfg->tb_to_xs = tb_to_xs;
686 /* If platform provided a timezone (pmac), we correct the time */
687 if (timezone_offset) {
688 sys_tz.tz_minuteswest = -timezone_offset / 60;
689 sys_tz.tz_dsttime = 0;
690 xtime.tv_sec -= timezone_offset;
693 last_rtc_update = xtime.tv_sec;
694 set_normalized_timespec(&wall_to_monotonic,
695 -xtime.tv_sec, -xtime.tv_nsec);
696 write_sequnlock_irqrestore(&xtime_lock, flags);
698 /* Not exact, but the timer interrupt takes care of this */
699 set_dec(tb_ticks_per_jiffy);
703 * After adjtimex is called, adjust the conversion of tb ticks
704 * to microseconds to keep do_gettimeofday synchronized
707 * Use the time_adjust, time_freq and time_offset computed by adjtimex to
708 * adjust the frequency.
711 /* #define DEBUG_PPC_ADJTIMEX 1 */
713 void ppc_adjtimex(void)
716 unsigned long den, new_tb_ticks_per_sec, tb_ticks, old_xsec,
717 new_tb_to_xs, new_xsec, new_stamp_xsec;
718 unsigned long tb_ticks_per_sec_delta;
719 long delta_freq, ltemp;
720 struct div_result divres;
722 long singleshot_ppm = 0;
725 * Compute parts per million frequency adjustment to
726 * accomplish the time adjustment implied by time_offset to be
727 * applied over the elapsed time indicated by time_constant.
728 * Use SHIFT_USEC to get it into the same units as
731 if ( time_offset < 0 ) {
732 ltemp = -time_offset;
733 ltemp <<= SHIFT_USEC - SHIFT_UPDATE;
734 ltemp >>= SHIFT_KG + time_constant;
738 ltemp <<= SHIFT_USEC - SHIFT_UPDATE;
739 ltemp >>= SHIFT_KG + time_constant;
742 /* If there is a single shot time adjustment in progress */
744 #ifdef DEBUG_PPC_ADJTIMEX
745 printk("ppc_adjtimex: ");
746 if ( adjusting_time == 0 )
748 printk("single shot time_adjust = %ld\n", time_adjust);
754 * Compute parts per million frequency adjustment
755 * to match time_adjust
757 singleshot_ppm = tickadj * HZ;
759 * The adjustment should be tickadj*HZ to match the code in
760 * linux/kernel/timer.c, but experiments show that this is too
761 * large. 3/4 of tickadj*HZ seems about right
763 singleshot_ppm -= singleshot_ppm / 4;
764 /* Use SHIFT_USEC to get it into the same units as time_freq */
765 singleshot_ppm <<= SHIFT_USEC;
766 if ( time_adjust < 0 )
767 singleshot_ppm = -singleshot_ppm;
770 #ifdef DEBUG_PPC_ADJTIMEX
771 if ( adjusting_time )
772 printk("ppc_adjtimex: ending single shot time_adjust\n");
777 /* Add up all of the frequency adjustments */
778 delta_freq = time_freq + ltemp + singleshot_ppm;
781 * Compute a new value for tb_ticks_per_sec based on
782 * the frequency adjustment
784 den = 1000000 * (1 << (SHIFT_USEC - 8));
785 if ( delta_freq < 0 ) {
786 tb_ticks_per_sec_delta = ( tb_ticks_per_sec * ( (-delta_freq) >> (SHIFT_USEC - 8))) / den;
787 new_tb_ticks_per_sec = tb_ticks_per_sec + tb_ticks_per_sec_delta;
790 tb_ticks_per_sec_delta = ( tb_ticks_per_sec * ( delta_freq >> (SHIFT_USEC - 8))) / den;
791 new_tb_ticks_per_sec = tb_ticks_per_sec - tb_ticks_per_sec_delta;
794 #ifdef DEBUG_PPC_ADJTIMEX
795 printk("ppc_adjtimex: ltemp = %ld, time_freq = %ld, singleshot_ppm = %ld\n", ltemp, time_freq, singleshot_ppm);
796 printk("ppc_adjtimex: tb_ticks_per_sec - base = %ld new = %ld\n", tb_ticks_per_sec, new_tb_ticks_per_sec);
800 * Compute a new value of tb_to_xs (used to convert tb to
801 * microseconds) and a new value of stamp_xsec which is the
802 * time (in 1/2^20 second units) corresponding to
803 * tb_orig_stamp. This new value of stamp_xsec compensates
804 * for the change in frequency (implied by the new tb_to_xs)
805 * which guarantees that the current time remains the same.
807 write_seqlock_irqsave( &xtime_lock, flags );
808 tb_ticks = get_tb() - do_gtod.varp->tb_orig_stamp;
809 div128_by_32(1024*1024, 0, new_tb_ticks_per_sec, &divres);
810 new_tb_to_xs = divres.result_low;
811 new_xsec = mulhdu(tb_ticks, new_tb_to_xs);
813 old_xsec = mulhdu(tb_ticks, do_gtod.varp->tb_to_xs);
814 new_stamp_xsec = do_gtod.varp->stamp_xsec + old_xsec - new_xsec;
816 update_gtod(do_gtod.varp->tb_orig_stamp, new_stamp_xsec, new_tb_to_xs);
818 write_sequnlock_irqrestore( &xtime_lock, flags );
819 #endif /* CONFIG_PPC64 */
824 #define STARTOFTIME 1970
825 #define SECDAY 86400L
826 #define SECYR (SECDAY * 365)
827 #define leapyear(year) ((year) % 4 == 0 && \
828 ((year) % 100 != 0 || (year) % 400 == 0))
829 #define days_in_year(a) (leapyear(a) ? 366 : 365)
830 #define days_in_month(a) (month_days[(a) - 1])
832 static int month_days[12] = {
833 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
837 * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
839 void GregorianDay(struct rtc_time * tm)
844 int MonthOffset[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
846 lastYear = tm->tm_year - 1;
849 * Number of leap corrections to apply up to end of last year
851 leapsToDate = lastYear / 4 - lastYear / 100 + lastYear / 400;
854 * This year is a leap year if it is divisible by 4 except when it is
855 * divisible by 100 unless it is divisible by 400
857 * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 was
859 day = tm->tm_mon > 2 && leapyear(tm->tm_year);
861 day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] +
864 tm->tm_wday = day % 7;
867 void to_tm(int tim, struct rtc_time * tm)
870 register long hms, day;
875 /* Hours, minutes, seconds are easy */
876 tm->tm_hour = hms / 3600;
877 tm->tm_min = (hms % 3600) / 60;
878 tm->tm_sec = (hms % 3600) % 60;
880 /* Number of years in days */
881 for (i = STARTOFTIME; day >= days_in_year(i); i++)
882 day -= days_in_year(i);
885 /* Number of months in days left */
886 if (leapyear(tm->tm_year))
887 days_in_month(FEBRUARY) = 29;
888 for (i = 1; day >= days_in_month(i); i++)
889 day -= days_in_month(i);
890 days_in_month(FEBRUARY) = 28;
893 /* Days are what is left over (+1) from all that. */
894 tm->tm_mday = day + 1;
897 * Determine the day of week
902 /* Auxiliary function to compute scaling factors */
903 /* Actually the choice of a timebase running at 1/4 the of the bus
904 * frequency giving resolution of a few tens of nanoseconds is quite nice.
905 * It makes this computation very precise (27-28 bits typically) which
906 * is optimistic considering the stability of most processor clock
907 * oscillators and the precision with which the timebase frequency
908 * is measured but does not harm.
910 unsigned mulhwu_scale_factor(unsigned inscale, unsigned outscale)
912 unsigned mlt=0, tmp, err;
913 /* No concern for performance, it's done once: use a stupid
914 * but safe and compact method to find the multiplier.
917 for (tmp = 1U<<31; tmp != 0; tmp >>= 1) {
918 if (mulhwu(inscale, mlt|tmp) < outscale)
922 /* We might still be off by 1 for the best approximation.
923 * A side effect of this is that if outscale is too large
924 * the returned value will be zero.
925 * Many corner cases have been checked and seem to work,
926 * some might have been forgotten in the test however.
929 err = inscale * (mlt+1);
930 if (err <= inscale/2)
936 * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
939 void div128_by_32(u64 dividend_high, u64 dividend_low,
940 unsigned divisor, struct div_result *dr)
942 unsigned long a, b, c, d;
943 unsigned long w, x, y, z;
946 a = dividend_high >> 32;
947 b = dividend_high & 0xffffffff;
948 c = dividend_low >> 32;
949 d = dividend_low & 0xffffffff;
952 ra = ((u64)(a - (w * divisor)) << 32) + b;
956 rb = ((ra - (x * divisor)) << 32) + c;
959 rc = ((rb - (y * divisor)) << 32) + d;
963 /* for 32-bit, use do_div from div64.h */
964 rb = ((u64) do_div(ra, divisor) << 32) + c;
967 rc = ((u64) do_div(rb, divisor) << 32) + d;
974 dr->result_high = ((u64)w << 32) + x;
975 dr->result_low = ((u64)y << 32) + z;