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>
53 #include <linux/jiffies.h>
54 #include <linux/posix-timers.h>
57 #include <asm/processor.h>
58 #include <asm/nvram.h>
59 #include <asm/cache.h>
60 #include <asm/machdep.h>
61 #include <asm/uaccess.h>
65 #include <asm/div64.h>
67 #include <asm/vdso_datapage.h>
69 #include <asm/firmware.h>
71 #ifdef CONFIG_PPC_ISERIES
72 #include <asm/iseries/it_lp_queue.h>
73 #include <asm/iseries/hv_call_xm.h>
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;
102 EXPORT_SYMBOL(tb_ticks_per_sec); /* for cputime_t conversions */
106 #define TICKLEN_SCALE (SHIFT_SCALE - 10)
107 u64 last_tick_len; /* units are ns / 2^TICKLEN_SCALE */
108 u64 ticklen_to_xs; /* 0.64 fraction */
110 /* If last_tick_len corresponds to about 1/HZ seconds, then
111 last_tick_len << TICKLEN_SHIFT will be about 2^63. */
112 #define TICKLEN_SHIFT (63 - 30 - TICKLEN_SCALE + SHIFT_HZ)
114 DEFINE_SPINLOCK(rtc_lock);
115 EXPORT_SYMBOL_GPL(rtc_lock);
118 unsigned tb_to_ns_shift;
120 struct gettimeofday_struct do_gtod;
122 extern unsigned long wall_jiffies;
124 extern struct timezone sys_tz;
125 static long timezone_offset;
127 unsigned long ppc_proc_freq;
128 unsigned long ppc_tb_freq;
130 u64 tb_last_jiffy __cacheline_aligned_in_smp;
131 unsigned long tb_last_stamp;
134 * Note that on ppc32 this only stores the bottom 32 bits of
135 * the timebase value, but that's enough to tell when a jiffy
138 DEFINE_PER_CPU(unsigned long, last_jiffy);
140 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
142 * Factors for converting from cputime_t (timebase ticks) to
143 * jiffies, milliseconds, seconds, and clock_t (1/USER_HZ seconds).
144 * These are all stored as 0.64 fixed-point binary fractions.
146 u64 __cputime_jiffies_factor;
147 EXPORT_SYMBOL(__cputime_jiffies_factor);
148 u64 __cputime_msec_factor;
149 EXPORT_SYMBOL(__cputime_msec_factor);
150 u64 __cputime_sec_factor;
151 EXPORT_SYMBOL(__cputime_sec_factor);
152 u64 __cputime_clockt_factor;
153 EXPORT_SYMBOL(__cputime_clockt_factor);
155 static void calc_cputime_factors(void)
157 struct div_result res;
159 div128_by_32(HZ, 0, tb_ticks_per_sec, &res);
160 __cputime_jiffies_factor = res.result_low;
161 div128_by_32(1000, 0, tb_ticks_per_sec, &res);
162 __cputime_msec_factor = res.result_low;
163 div128_by_32(1, 0, tb_ticks_per_sec, &res);
164 __cputime_sec_factor = res.result_low;
165 div128_by_32(USER_HZ, 0, tb_ticks_per_sec, &res);
166 __cputime_clockt_factor = res.result_low;
170 * Read the PURR on systems that have it, otherwise the timebase.
172 static u64 read_purr(void)
174 if (cpu_has_feature(CPU_FTR_PURR))
175 return mfspr(SPRN_PURR);
180 * Account time for a transition between system, hard irq
183 void account_system_vtime(struct task_struct *tsk)
188 local_irq_save(flags);
190 delta = now - get_paca()->startpurr;
191 get_paca()->startpurr = now;
192 if (!in_interrupt()) {
193 delta += get_paca()->system_time;
194 get_paca()->system_time = 0;
196 account_system_time(tsk, 0, delta);
197 local_irq_restore(flags);
201 * Transfer the user and system times accumulated in the paca
202 * by the exception entry and exit code to the generic process
203 * user and system time records.
204 * Must be called with interrupts disabled.
206 void account_process_vtime(struct task_struct *tsk)
210 utime = get_paca()->user_time;
211 get_paca()->user_time = 0;
212 account_user_time(tsk, utime);
215 static void account_process_time(struct pt_regs *regs)
217 int cpu = smp_processor_id();
219 account_process_vtime(current);
221 if (rcu_pending(cpu))
222 rcu_check_callbacks(cpu, user_mode(regs));
224 run_posix_cpu_timers(current);
227 #ifdef CONFIG_PPC_SPLPAR
229 * Stuff for accounting stolen time.
231 struct cpu_purr_data {
232 int initialized; /* thread is running */
233 u64 tb0; /* timebase at origin time */
234 u64 purr0; /* PURR at origin time */
235 u64 tb; /* last TB value read */
236 u64 purr; /* last PURR value read */
237 u64 stolen; /* stolen time so far */
241 static DEFINE_PER_CPU(struct cpu_purr_data, cpu_purr_data);
243 static void snapshot_tb_and_purr(void *data)
245 struct cpu_purr_data *p = &__get_cpu_var(cpu_purr_data);
248 p->purr0 = mfspr(SPRN_PURR);
256 * Called during boot when all cpus have come up.
258 void snapshot_timebases(void)
262 if (!cpu_has_feature(CPU_FTR_PURR))
265 spin_lock_init(&per_cpu(cpu_purr_data, cpu).lock);
266 on_each_cpu(snapshot_tb_and_purr, NULL, 0, 1);
269 void calculate_steal_time(void)
273 struct cpu_purr_data *p0, *pme, *phim;
276 if (!cpu_has_feature(CPU_FTR_PURR))
278 cpu = smp_processor_id();
279 pme = &per_cpu(cpu_purr_data, cpu);
280 if (!pme->initialized)
281 return; /* this can happen in early boot */
282 p0 = &per_cpu(cpu_purr_data, cpu & ~1);
283 phim = &per_cpu(cpu_purr_data, cpu ^ 1);
284 spin_lock(&p0->lock);
286 purr = mfspr(SPRN_PURR) - pme->purr0;
287 if (!phim->initialized || !cpu_online(cpu ^ 1)) {
288 stolen = (tb - pme->tb) - (purr - pme->purr);
293 stolen = phim->tb - t0 - phim->purr - purr - p0->stolen;
296 account_steal_time(current, stolen);
297 p0->stolen += stolen;
301 spin_unlock(&p0->lock);
305 * Must be called before the cpu is added to the online map when
306 * a cpu is being brought up at runtime.
308 static void snapshot_purr(void)
312 struct cpu_purr_data *p0, *pme, *phim;
315 if (!cpu_has_feature(CPU_FTR_PURR))
317 cpu = smp_processor_id();
318 pme = &per_cpu(cpu_purr_data, cpu);
319 p0 = &per_cpu(cpu_purr_data, cpu & ~1);
320 phim = &per_cpu(cpu_purr_data, cpu ^ 1);
321 spin_lock_irqsave(&p0->lock, flags);
322 pme->tb = pme->tb0 = mftb();
323 purr = mfspr(SPRN_PURR);
324 if (!phim->initialized) {
328 /* set p->purr and p->purr0 for no change in p0->stolen */
329 pme->purr = phim->tb - phim->tb0 - phim->purr - p0->stolen;
330 pme->purr0 = purr - pme->purr;
332 pme->initialized = 1;
333 spin_unlock_irqrestore(&p0->lock, flags);
336 #endif /* CONFIG_PPC_SPLPAR */
338 #else /* ! CONFIG_VIRT_CPU_ACCOUNTING */
339 #define calc_cputime_factors()
340 #define account_process_time(regs) update_process_times(user_mode(regs))
341 #define calculate_steal_time() do { } while (0)
344 #if !(defined(CONFIG_VIRT_CPU_ACCOUNTING) && defined(CONFIG_PPC_SPLPAR))
345 #define snapshot_purr() do { } while (0)
349 * Called when a cpu comes up after the system has finished booting,
350 * i.e. as a result of a hotplug cpu action.
352 void snapshot_timebase(void)
354 __get_cpu_var(last_jiffy) = get_tb();
358 void __delay(unsigned long loops)
366 /* the RTCL register wraps at 1000000000 */
367 diff = get_rtcl() - start;
370 } while (diff < loops);
373 while (get_tbl() - start < loops)
378 EXPORT_SYMBOL(__delay);
380 void udelay(unsigned long usecs)
382 __delay(tb_ticks_per_usec * usecs);
384 EXPORT_SYMBOL(udelay);
386 static __inline__ void timer_check_rtc(void)
389 * update the rtc when needed, this should be performed on the
390 * right fraction of a second. Half or full second ?
391 * Full second works on mk48t59 clocks, others need testing.
392 * Note that this update is basically only used through
393 * the adjtimex system calls. Setting the HW clock in
394 * any other way is a /dev/rtc and userland business.
395 * This is still wrong by -0.5/+1.5 jiffies because of the
396 * timer interrupt resolution and possible delay, but here we
397 * hit a quantization limit which can only be solved by higher
398 * resolution timers and decoupling time management from timer
399 * interrupts. This is also wrong on the clocks
400 * which require being written at the half second boundary.
401 * We should have an rtc call that only sets the minutes and
402 * seconds like on Intel to avoid problems with non UTC clocks.
404 if (ppc_md.set_rtc_time && ntp_synced() &&
405 xtime.tv_sec - last_rtc_update >= 659 &&
406 abs((xtime.tv_nsec/1000) - (1000000-1000000/HZ)) < 500000/HZ) {
408 to_tm(xtime.tv_sec + 1 + timezone_offset, &tm);
411 if (ppc_md.set_rtc_time(&tm) == 0)
412 last_rtc_update = xtime.tv_sec + 1;
414 /* Try again one minute later */
415 last_rtc_update += 60;
420 * This version of gettimeofday has microsecond resolution.
422 static inline void __do_gettimeofday(struct timeval *tv, u64 tb_val)
424 unsigned long sec, usec;
426 struct gettimeofday_vars *temp_varp;
427 u64 temp_tb_to_xs, temp_stamp_xsec;
430 * These calculations are faster (gets rid of divides)
431 * if done in units of 1/2^20 rather than microseconds.
432 * The conversion to microseconds at the end is done
433 * without a divide (and in fact, without a multiply)
435 temp_varp = do_gtod.varp;
436 tb_ticks = tb_val - temp_varp->tb_orig_stamp;
437 temp_tb_to_xs = temp_varp->tb_to_xs;
438 temp_stamp_xsec = temp_varp->stamp_xsec;
439 xsec = temp_stamp_xsec + mulhdu(tb_ticks, temp_tb_to_xs);
440 sec = xsec / XSEC_PER_SEC;
441 usec = (unsigned long)xsec & (XSEC_PER_SEC - 1);
442 usec = SCALE_XSEC(usec, 1000000);
448 void do_gettimeofday(struct timeval *tv)
451 /* do this the old way */
452 unsigned long flags, seq;
453 unsigned int sec, nsec, usec;
456 seq = read_seqbegin_irqsave(&xtime_lock, flags);
458 nsec = xtime.tv_nsec + tb_ticks_since(tb_last_stamp);
459 } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
461 while (usec >= 1000000) {
469 __do_gettimeofday(tv, get_tb());
472 EXPORT_SYMBOL(do_gettimeofday);
475 * There are two copies of tb_to_xs and stamp_xsec so that no
476 * lock is needed to access and use these values in
477 * do_gettimeofday. We alternate the copies and as long as a
478 * reasonable time elapses between changes, there will never
479 * be inconsistent values. ntpd has a minimum of one minute
482 static inline void update_gtod(u64 new_tb_stamp, u64 new_stamp_xsec,
486 struct gettimeofday_vars *temp_varp;
488 temp_idx = (do_gtod.var_idx == 0);
489 temp_varp = &do_gtod.vars[temp_idx];
491 temp_varp->tb_to_xs = new_tb_to_xs;
492 temp_varp->tb_orig_stamp = new_tb_stamp;
493 temp_varp->stamp_xsec = new_stamp_xsec;
495 do_gtod.varp = temp_varp;
496 do_gtod.var_idx = temp_idx;
499 * tb_update_count is used to allow the userspace gettimeofday code
500 * to assure itself that it sees a consistent view of the tb_to_xs and
501 * stamp_xsec variables. It reads the tb_update_count, then reads
502 * tb_to_xs and stamp_xsec and then reads tb_update_count again. If
503 * the two values of tb_update_count match and are even then the
504 * tb_to_xs and stamp_xsec values are consistent. If not, then it
505 * loops back and reads them again until this criteria is met.
507 ++(vdso_data->tb_update_count);
509 vdso_data->tb_orig_stamp = new_tb_stamp;
510 vdso_data->stamp_xsec = new_stamp_xsec;
511 vdso_data->tb_to_xs = new_tb_to_xs;
512 vdso_data->wtom_clock_sec = wall_to_monotonic.tv_sec;
513 vdso_data->wtom_clock_nsec = wall_to_monotonic.tv_nsec;
515 ++(vdso_data->tb_update_count);
519 * When the timebase - tb_orig_stamp gets too big, we do a manipulation
520 * between tb_orig_stamp and stamp_xsec. The goal here is to keep the
521 * difference tb - tb_orig_stamp small enough to always fit inside a
522 * 32 bits number. This is a requirement of our fast 32 bits userland
523 * implementation in the vdso. If we "miss" a call to this function
524 * (interrupt latency, CPU locked in a spinlock, ...) and we end up
525 * with a too big difference, then the vdso will fallback to calling
528 static __inline__ void timer_recalc_offset(u64 cur_tb)
530 unsigned long offset;
536 tlen = current_tick_length();
537 offset = cur_tb - do_gtod.varp->tb_orig_stamp;
538 if (tlen == last_tick_len && offset < 0x80000000u) {
539 /* check that we're still in sync; if not, resync */
541 __do_gettimeofday(&tv, cur_tb);
542 if (tv.tv_sec <= xtime.tv_sec &&
543 (tv.tv_sec < xtime.tv_sec ||
544 tv.tv_usec * 1000 <= xtime.tv_nsec))
547 if (tlen != last_tick_len) {
548 t2x = mulhdu(tlen << TICKLEN_SHIFT, ticklen_to_xs);
549 last_tick_len = tlen;
551 t2x = do_gtod.varp->tb_to_xs;
552 new_stamp_xsec = (u64) xtime.tv_nsec * XSEC_PER_SEC;
553 do_div(new_stamp_xsec, 1000000000);
554 new_stamp_xsec += (u64) xtime.tv_sec * XSEC_PER_SEC;
555 update_gtod(cur_tb, new_stamp_xsec, t2x);
559 unsigned long profile_pc(struct pt_regs *regs)
561 unsigned long pc = instruction_pointer(regs);
563 if (in_lock_functions(pc))
568 EXPORT_SYMBOL(profile_pc);
571 #ifdef CONFIG_PPC_ISERIES
574 * This function recalibrates the timebase based on the 49-bit time-of-day
575 * value in the Titan chip. The Titan is much more accurate than the value
576 * returned by the service processor for the timebase frequency.
579 static void iSeries_tb_recal(void)
581 struct div_result divres;
582 unsigned long titan, tb;
584 titan = HvCallXm_loadTod();
585 if ( iSeries_recal_titan ) {
586 unsigned long tb_ticks = tb - iSeries_recal_tb;
587 unsigned long titan_usec = (titan - iSeries_recal_titan) >> 12;
588 unsigned long new_tb_ticks_per_sec = (tb_ticks * USEC_PER_SEC)/titan_usec;
589 unsigned long new_tb_ticks_per_jiffy = (new_tb_ticks_per_sec+(HZ/2))/HZ;
590 long tick_diff = new_tb_ticks_per_jiffy - tb_ticks_per_jiffy;
592 /* make sure tb_ticks_per_sec and tb_ticks_per_jiffy are consistent */
593 new_tb_ticks_per_sec = new_tb_ticks_per_jiffy * HZ;
595 if ( tick_diff < 0 ) {
596 tick_diff = -tick_diff;
600 if ( tick_diff < tb_ticks_per_jiffy/25 ) {
601 printk( "Titan recalibrate: new tb_ticks_per_jiffy = %lu (%c%ld)\n",
602 new_tb_ticks_per_jiffy, sign, tick_diff );
603 tb_ticks_per_jiffy = new_tb_ticks_per_jiffy;
604 tb_ticks_per_sec = new_tb_ticks_per_sec;
605 calc_cputime_factors();
606 div128_by_32( XSEC_PER_SEC, 0, tb_ticks_per_sec, &divres );
607 do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
608 tb_to_xs = divres.result_low;
609 do_gtod.varp->tb_to_xs = tb_to_xs;
610 vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
611 vdso_data->tb_to_xs = tb_to_xs;
614 printk( "Titan recalibrate: FAILED (difference > 4 percent)\n"
615 " new tb_ticks_per_jiffy = %lu\n"
616 " old tb_ticks_per_jiffy = %lu\n",
617 new_tb_ticks_per_jiffy, tb_ticks_per_jiffy );
621 iSeries_recal_titan = titan;
622 iSeries_recal_tb = tb;
627 * For iSeries shared processors, we have to let the hypervisor
628 * set the hardware decrementer. We set a virtual decrementer
629 * in the lppaca and call the hypervisor if the virtual
630 * decrementer is less than the current value in the hardware
631 * decrementer. (almost always the new decrementer value will
632 * be greater than the current hardware decementer so the hypervisor
633 * call will not be needed)
637 * timer_interrupt - gets called when the decrementer overflows,
638 * with interrupts disabled.
640 void timer_interrupt(struct pt_regs * regs)
643 int cpu = smp_processor_id();
647 if (atomic_read(&ppc_n_lost_interrupts) != 0)
653 profile_tick(CPU_PROFILING, regs);
654 calculate_steal_time();
656 #ifdef CONFIG_PPC_ISERIES
657 get_lppaca()->int_dword.fields.decr_int = 0;
660 while ((ticks = tb_ticks_since(per_cpu(last_jiffy, cpu)))
661 >= tb_ticks_per_jiffy) {
662 /* Update last_jiffy */
663 per_cpu(last_jiffy, cpu) += tb_ticks_per_jiffy;
664 /* Handle RTCL overflow on 601 */
665 if (__USE_RTC() && per_cpu(last_jiffy, cpu) >= 1000000000)
666 per_cpu(last_jiffy, cpu) -= 1000000000;
669 * We cannot disable the decrementer, so in the period
670 * between this cpu's being marked offline in cpu_online_map
671 * and calling stop-self, it is taking timer interrupts.
672 * Avoid calling into the scheduler rebalancing code if this
675 if (!cpu_is_offline(cpu))
676 account_process_time(regs);
679 * No need to check whether cpu is offline here; boot_cpuid
680 * should have been fixed up by now.
682 if (cpu != boot_cpuid)
685 write_seqlock(&xtime_lock);
686 tb_last_jiffy += tb_ticks_per_jiffy;
687 tb_last_stamp = per_cpu(last_jiffy, cpu);
689 timer_recalc_offset(tb_last_jiffy);
691 write_sequnlock(&xtime_lock);
694 next_dec = tb_ticks_per_jiffy - ticks;
697 #ifdef CONFIG_PPC_ISERIES
698 if (hvlpevent_is_pending())
699 process_hvlpevents(regs);
703 /* collect purr register values often, for accurate calculations */
704 if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
705 struct cpu_usage *cu = &__get_cpu_var(cpu_usage_array);
706 cu->current_tb = mfspr(SPRN_PURR);
713 void wakeup_decrementer(void)
718 * The timebase gets saved on sleep and restored on wakeup,
719 * so all we need to do is to reset the decrementer.
721 ticks = tb_ticks_since(__get_cpu_var(last_jiffy));
722 if (ticks < tb_ticks_per_jiffy)
723 ticks = tb_ticks_per_jiffy - ticks;
730 void __init smp_space_timers(unsigned int max_cpus)
733 unsigned long half = tb_ticks_per_jiffy / 2;
734 unsigned long offset = tb_ticks_per_jiffy / max_cpus;
735 unsigned long previous_tb = per_cpu(last_jiffy, boot_cpuid);
737 /* make sure tb > per_cpu(last_jiffy, cpu) for all cpus always */
738 previous_tb -= tb_ticks_per_jiffy;
740 * The stolen time calculation for POWER5 shared-processor LPAR
741 * systems works better if the two threads' timebase interrupts
742 * are staggered by half a jiffy with respect to each other.
747 if (i == (boot_cpuid ^ 1))
748 per_cpu(last_jiffy, i) =
749 per_cpu(last_jiffy, boot_cpuid) - half;
751 per_cpu(last_jiffy, i) =
752 per_cpu(last_jiffy, i ^ 1) + half;
754 previous_tb += offset;
755 per_cpu(last_jiffy, i) = previous_tb;
762 * Scheduler clock - returns current time in nanosec units.
764 * Note: mulhdu(a, b) (multiply high double unsigned) returns
765 * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
766 * are 64-bit unsigned numbers.
768 unsigned long long sched_clock(void)
772 return mulhdu(get_tb(), tb_to_ns_scale) << tb_to_ns_shift;
775 int do_settimeofday(struct timespec *tv)
777 time_t wtm_sec, new_sec = tv->tv_sec;
778 long wtm_nsec, new_nsec = tv->tv_nsec;
781 unsigned long tb_delta;
783 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
786 write_seqlock_irqsave(&xtime_lock, flags);
789 * Updating the RTC is not the job of this code. If the time is
790 * stepped under NTP, the RTC will be updated after STA_UNSYNC
791 * is cleared. Tools like clock/hwclock either copy the RTC
792 * to the system time, in which case there is no point in writing
793 * to the RTC again, or write to the RTC but then they don't call
794 * settimeofday to perform this operation.
796 #ifdef CONFIG_PPC_ISERIES
797 if (first_settimeofday) {
799 first_settimeofday = 0;
804 * Subtract off the number of nanoseconds since the
805 * beginning of the last tick.
806 * Note that since we don't increment jiffies_64 anywhere other
807 * than in do_timer (since we don't have a lost tick problem),
808 * wall_jiffies will always be the same as jiffies,
809 * and therefore the (jiffies - wall_jiffies) computation
812 tb_delta = tb_ticks_since(tb_last_stamp);
813 tb_delta = mulhdu(tb_delta, do_gtod.varp->tb_to_xs); /* in xsec */
814 new_nsec -= SCALE_XSEC(tb_delta, 1000000000);
816 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - new_sec);
817 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - new_nsec);
819 set_normalized_timespec(&xtime, new_sec, new_nsec);
820 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
822 /* In case of a large backwards jump in time with NTP, we want the
823 * clock to be updated as soon as the PLL is again in lock.
825 last_rtc_update = new_sec - 658;
829 new_xsec = xtime.tv_nsec;
831 new_xsec *= XSEC_PER_SEC;
832 do_div(new_xsec, NSEC_PER_SEC);
834 new_xsec += (u64)xtime.tv_sec * XSEC_PER_SEC;
835 update_gtod(tb_last_jiffy, new_xsec, do_gtod.varp->tb_to_xs);
837 vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
838 vdso_data->tz_dsttime = sys_tz.tz_dsttime;
840 write_sequnlock_irqrestore(&xtime_lock, flags);
845 EXPORT_SYMBOL(do_settimeofday);
847 void __init generic_calibrate_decr(void)
849 struct device_node *cpu;
854 * The cpu node should have a timebase-frequency property
855 * to tell us the rate at which the decrementer counts.
857 cpu = of_find_node_by_type(NULL, "cpu");
859 ppc_tb_freq = DEFAULT_TB_FREQ; /* hardcoded default */
862 fp = (unsigned int *)get_property(cpu, "timebase-frequency",
870 printk(KERN_ERR "WARNING: Estimating decrementer frequency "
873 ppc_proc_freq = DEFAULT_PROC_FREQ;
876 fp = (unsigned int *)get_property(cpu, "clock-frequency",
884 /* Set the time base to zero */
888 /* Clear any pending timer interrupts */
889 mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS);
891 /* Enable decrementer interrupt */
892 mtspr(SPRN_TCR, TCR_DIE);
895 printk(KERN_ERR "WARNING: Estimating processor frequency "
901 unsigned long get_boot_time(void)
905 if (ppc_md.get_boot_time)
906 return ppc_md.get_boot_time();
907 if (!ppc_md.get_rtc_time)
909 ppc_md.get_rtc_time(&tm);
910 return mktime(tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday,
911 tm.tm_hour, tm.tm_min, tm.tm_sec);
914 /* This function is only called on the boot processor */
915 void __init time_init(void)
918 unsigned long tm = 0;
919 struct div_result res;
923 if (ppc_md.time_init != NULL)
924 timezone_offset = ppc_md.time_init();
927 /* 601 processor: dec counts down by 128 every 128ns */
928 ppc_tb_freq = 1000000000;
929 tb_last_stamp = get_rtcl();
930 tb_last_jiffy = tb_last_stamp;
932 /* Normal PowerPC with timebase register */
933 ppc_md.calibrate_decr();
934 printk(KERN_INFO "time_init: decrementer frequency = %lu.%.6lu MHz\n",
935 ppc_tb_freq / 1000000, ppc_tb_freq % 1000000);
936 printk(KERN_INFO "time_init: processor frequency = %lu.%.6lu MHz\n",
937 ppc_proc_freq / 1000000, ppc_proc_freq % 1000000);
938 tb_last_stamp = tb_last_jiffy = get_tb();
941 tb_ticks_per_jiffy = ppc_tb_freq / HZ;
942 tb_ticks_per_sec = ppc_tb_freq;
943 tb_ticks_per_usec = ppc_tb_freq / 1000000;
944 tb_to_us = mulhwu_scale_factor(ppc_tb_freq, 1000000);
945 calc_cputime_factors();
948 * Calculate the length of each tick in ns. It will not be
949 * exactly 1e9/HZ unless ppc_tb_freq is divisible by HZ.
950 * We compute 1e9 * tb_ticks_per_jiffy / ppc_tb_freq,
953 x = (u64) NSEC_PER_SEC * tb_ticks_per_jiffy + ppc_tb_freq - 1;
954 do_div(x, ppc_tb_freq);
956 last_tick_len = x << TICKLEN_SCALE;
959 * Compute ticklen_to_xs, which is a factor which gets multiplied
960 * by (last_tick_len << TICKLEN_SHIFT) to get a tb_to_xs value.
962 * ticklen_to_xs = 2^N / (tb_ticks_per_jiffy * 1e9)
963 * where N = 64 + 20 - TICKLEN_SCALE - TICKLEN_SHIFT
964 * so as to give the result as a 0.64 fixed-point fraction.
966 div128_by_32(1ULL << (64 + 20 - TICKLEN_SCALE - TICKLEN_SHIFT), 0,
967 tb_ticks_per_jiffy, &res);
968 div128_by_32(res.result_high, res.result_low, NSEC_PER_SEC, &res);
969 ticklen_to_xs = res.result_low;
971 /* Compute tb_to_xs from tick_nsec */
972 tb_to_xs = mulhdu(last_tick_len << TICKLEN_SHIFT, ticklen_to_xs);
975 * Compute scale factor for sched_clock.
976 * The calibrate_decr() function has set tb_ticks_per_sec,
977 * which is the timebase frequency.
978 * We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
979 * the 128-bit result as a 64.64 fixed-point number.
980 * We then shift that number right until it is less than 1.0,
981 * giving us the scale factor and shift count to use in
984 div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
985 scale = res.result_low;
986 for (shift = 0; res.result_high != 0; ++shift) {
987 scale = (scale >> 1) | (res.result_high << 63);
988 res.result_high >>= 1;
990 tb_to_ns_scale = scale;
991 tb_to_ns_shift = shift;
993 #ifdef CONFIG_PPC_ISERIES
994 if (!piranha_simulator)
996 tm = get_boot_time();
998 write_seqlock_irqsave(&xtime_lock, flags);
1000 /* If platform provided a timezone (pmac), we correct the time */
1001 if (timezone_offset) {
1002 sys_tz.tz_minuteswest = -timezone_offset / 60;
1003 sys_tz.tz_dsttime = 0;
1004 tm -= timezone_offset;
1009 do_gtod.varp = &do_gtod.vars[0];
1010 do_gtod.var_idx = 0;
1011 do_gtod.varp->tb_orig_stamp = tb_last_jiffy;
1012 __get_cpu_var(last_jiffy) = tb_last_stamp;
1013 do_gtod.varp->stamp_xsec = (u64) xtime.tv_sec * XSEC_PER_SEC;
1014 do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
1015 do_gtod.varp->tb_to_xs = tb_to_xs;
1016 do_gtod.tb_to_us = tb_to_us;
1018 vdso_data->tb_orig_stamp = tb_last_jiffy;
1019 vdso_data->tb_update_count = 0;
1020 vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
1021 vdso_data->stamp_xsec = (u64) xtime.tv_sec * XSEC_PER_SEC;
1022 vdso_data->tb_to_xs = tb_to_xs;
1026 last_rtc_update = xtime.tv_sec;
1027 set_normalized_timespec(&wall_to_monotonic,
1028 -xtime.tv_sec, -xtime.tv_nsec);
1029 write_sequnlock_irqrestore(&xtime_lock, flags);
1031 /* Not exact, but the timer interrupt takes care of this */
1032 set_dec(tb_ticks_per_jiffy);
1037 #define STARTOFTIME 1970
1038 #define SECDAY 86400L
1039 #define SECYR (SECDAY * 365)
1040 #define leapyear(year) ((year) % 4 == 0 && \
1041 ((year) % 100 != 0 || (year) % 400 == 0))
1042 #define days_in_year(a) (leapyear(a) ? 366 : 365)
1043 #define days_in_month(a) (month_days[(a) - 1])
1045 static int month_days[12] = {
1046 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
1050 * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
1052 void GregorianDay(struct rtc_time * tm)
1057 int MonthOffset[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
1059 lastYear = tm->tm_year - 1;
1062 * Number of leap corrections to apply up to end of last year
1064 leapsToDate = lastYear / 4 - lastYear / 100 + lastYear / 400;
1067 * This year is a leap year if it is divisible by 4 except when it is
1068 * divisible by 100 unless it is divisible by 400
1070 * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 was
1072 day = tm->tm_mon > 2 && leapyear(tm->tm_year);
1074 day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] +
1077 tm->tm_wday = day % 7;
1080 void to_tm(int tim, struct rtc_time * tm)
1083 register long hms, day;
1088 /* Hours, minutes, seconds are easy */
1089 tm->tm_hour = hms / 3600;
1090 tm->tm_min = (hms % 3600) / 60;
1091 tm->tm_sec = (hms % 3600) % 60;
1093 /* Number of years in days */
1094 for (i = STARTOFTIME; day >= days_in_year(i); i++)
1095 day -= days_in_year(i);
1098 /* Number of months in days left */
1099 if (leapyear(tm->tm_year))
1100 days_in_month(FEBRUARY) = 29;
1101 for (i = 1; day >= days_in_month(i); i++)
1102 day -= days_in_month(i);
1103 days_in_month(FEBRUARY) = 28;
1106 /* Days are what is left over (+1) from all that. */
1107 tm->tm_mday = day + 1;
1110 * Determine the day of week
1115 /* Auxiliary function to compute scaling factors */
1116 /* Actually the choice of a timebase running at 1/4 the of the bus
1117 * frequency giving resolution of a few tens of nanoseconds is quite nice.
1118 * It makes this computation very precise (27-28 bits typically) which
1119 * is optimistic considering the stability of most processor clock
1120 * oscillators and the precision with which the timebase frequency
1121 * is measured but does not harm.
1123 unsigned mulhwu_scale_factor(unsigned inscale, unsigned outscale)
1125 unsigned mlt=0, tmp, err;
1126 /* No concern for performance, it's done once: use a stupid
1127 * but safe and compact method to find the multiplier.
1130 for (tmp = 1U<<31; tmp != 0; tmp >>= 1) {
1131 if (mulhwu(inscale, mlt|tmp) < outscale)
1135 /* We might still be off by 1 for the best approximation.
1136 * A side effect of this is that if outscale is too large
1137 * the returned value will be zero.
1138 * Many corner cases have been checked and seem to work,
1139 * some might have been forgotten in the test however.
1142 err = inscale * (mlt+1);
1143 if (err <= inscale/2)
1149 * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
1152 void div128_by_32(u64 dividend_high, u64 dividend_low,
1153 unsigned divisor, struct div_result *dr)
1155 unsigned long a, b, c, d;
1156 unsigned long w, x, y, z;
1159 a = dividend_high >> 32;
1160 b = dividend_high & 0xffffffff;
1161 c = dividend_low >> 32;
1162 d = dividend_low & 0xffffffff;
1165 ra = ((u64)(a - (w * divisor)) << 32) + b;
1167 rb = ((u64) do_div(ra, divisor) << 32) + c;
1170 rc = ((u64) do_div(rb, divisor) << 32) + d;
1173 do_div(rc, divisor);
1176 dr->result_high = ((u64)w << 32) + x;
1177 dr->result_low = ((u64)y << 32) + z;