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/errno.h>
36 #include <linux/module.h>
37 #include <linux/sched.h>
38 #include <linux/kernel.h>
39 #include <linux/param.h>
40 #include <linux/string.h>
42 #include <linux/interrupt.h>
43 #include <linux/timex.h>
44 #include <linux/kernel_stat.h>
45 #include <linux/time.h>
46 #include <linux/init.h>
47 #include <linux/profile.h>
48 #include <linux/cpu.h>
49 #include <linux/security.h>
50 #include <linux/percpu.h>
51 #include <linux/rtc.h>
52 #include <linux/jiffies.h>
53 #include <linux/posix-timers.h>
54 #include <linux/irq.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>
68 #include <asm/firmware.h>
69 #ifdef CONFIG_PPC_ISERIES
70 #include <asm/iseries/it_lp_queue.h>
71 #include <asm/iseries/hv_call_xm.h>
74 /* powerpc clocksource/clockevent code */
76 #include <linux/clockchips.h>
77 #include <linux/clocksource.h>
79 static cycle_t rtc_read(void);
80 static struct clocksource clocksource_rtc = {
83 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
84 .mask = CLOCKSOURCE_MASK(64),
86 .mult = 0, /* To be filled in */
90 static cycle_t timebase_read(void);
91 static struct clocksource clocksource_timebase = {
94 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
95 .mask = CLOCKSOURCE_MASK(64),
97 .mult = 0, /* To be filled in */
98 .read = timebase_read,
101 #define DECREMENTER_MAX 0x7fffffff
103 static int decrementer_set_next_event(unsigned long evt,
104 struct clock_event_device *dev);
105 static void decrementer_set_mode(enum clock_event_mode mode,
106 struct clock_event_device *dev);
108 static struct clock_event_device decrementer_clockevent = {
109 .name = "decrementer",
112 .mult = 0, /* To be filled in */
114 .set_next_event = decrementer_set_next_event,
115 .set_mode = decrementer_set_mode,
116 .features = CLOCK_EVT_FEAT_ONESHOT,
119 static DEFINE_PER_CPU(struct clock_event_device, decrementers);
120 void init_decrementer_clockevent(void);
121 static DEFINE_PER_CPU(u64, decrementer_next_tb);
123 #ifdef CONFIG_PPC_ISERIES
124 static unsigned long __initdata iSeries_recal_titan;
125 static signed long __initdata iSeries_recal_tb;
127 /* Forward declaration is only needed for iSereis compiles */
128 void __init clocksource_init(void);
131 #define XSEC_PER_SEC (1024*1024)
134 #define SCALE_XSEC(xsec, max) (((xsec) * max) / XSEC_PER_SEC)
136 /* compute ((xsec << 12) * max) >> 32 */
137 #define SCALE_XSEC(xsec, max) mulhwu((xsec) << 12, max)
140 unsigned long tb_ticks_per_jiffy;
141 unsigned long tb_ticks_per_usec = 100; /* sane default */
142 EXPORT_SYMBOL(tb_ticks_per_usec);
143 unsigned long tb_ticks_per_sec;
144 EXPORT_SYMBOL(tb_ticks_per_sec); /* for cputime_t conversions */
148 #define TICKLEN_SCALE TICK_LENGTH_SHIFT
149 u64 last_tick_len; /* units are ns / 2^TICKLEN_SCALE */
150 u64 ticklen_to_xs; /* 0.64 fraction */
152 /* If last_tick_len corresponds to about 1/HZ seconds, then
153 last_tick_len << TICKLEN_SHIFT will be about 2^63. */
154 #define TICKLEN_SHIFT (63 - 30 - TICKLEN_SCALE + SHIFT_HZ)
156 DEFINE_SPINLOCK(rtc_lock);
157 EXPORT_SYMBOL_GPL(rtc_lock);
159 static u64 tb_to_ns_scale __read_mostly;
160 static unsigned tb_to_ns_shift __read_mostly;
161 static unsigned long boot_tb __read_mostly;
163 struct gettimeofday_struct do_gtod;
165 extern struct timezone sys_tz;
166 static long timezone_offset;
168 unsigned long ppc_proc_freq;
169 EXPORT_SYMBOL(ppc_proc_freq);
170 unsigned long ppc_tb_freq;
172 static u64 tb_last_jiffy __cacheline_aligned_in_smp;
173 static DEFINE_PER_CPU(u64, last_jiffy);
175 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
177 * Factors for converting from cputime_t (timebase ticks) to
178 * jiffies, milliseconds, seconds, and clock_t (1/USER_HZ seconds).
179 * These are all stored as 0.64 fixed-point binary fractions.
181 u64 __cputime_jiffies_factor;
182 EXPORT_SYMBOL(__cputime_jiffies_factor);
183 u64 __cputime_msec_factor;
184 EXPORT_SYMBOL(__cputime_msec_factor);
185 u64 __cputime_sec_factor;
186 EXPORT_SYMBOL(__cputime_sec_factor);
187 u64 __cputime_clockt_factor;
188 EXPORT_SYMBOL(__cputime_clockt_factor);
190 static void calc_cputime_factors(void)
192 struct div_result res;
194 div128_by_32(HZ, 0, tb_ticks_per_sec, &res);
195 __cputime_jiffies_factor = res.result_low;
196 div128_by_32(1000, 0, tb_ticks_per_sec, &res);
197 __cputime_msec_factor = res.result_low;
198 div128_by_32(1, 0, tb_ticks_per_sec, &res);
199 __cputime_sec_factor = res.result_low;
200 div128_by_32(USER_HZ, 0, tb_ticks_per_sec, &res);
201 __cputime_clockt_factor = res.result_low;
205 * Read the PURR on systems that have it, otherwise the timebase.
207 static u64 read_purr(void)
209 if (cpu_has_feature(CPU_FTR_PURR))
210 return mfspr(SPRN_PURR);
215 * Account time for a transition between system, hard irq
218 void account_system_vtime(struct task_struct *tsk)
223 local_irq_save(flags);
225 delta = now - get_paca()->startpurr;
226 get_paca()->startpurr = now;
227 if (!in_interrupt()) {
228 delta += get_paca()->system_time;
229 get_paca()->system_time = 0;
231 account_system_time(tsk, 0, delta);
232 local_irq_restore(flags);
236 * Transfer the user and system times accumulated in the paca
237 * by the exception entry and exit code to the generic process
238 * user and system time records.
239 * Must be called with interrupts disabled.
241 void account_process_vtime(struct task_struct *tsk)
245 utime = get_paca()->user_time;
246 get_paca()->user_time = 0;
247 account_user_time(tsk, utime);
250 static void account_process_time(struct pt_regs *regs)
252 int cpu = smp_processor_id();
254 account_process_vtime(current);
256 if (rcu_pending(cpu))
257 rcu_check_callbacks(cpu, user_mode(regs));
259 run_posix_cpu_timers(current);
263 * Stuff for accounting stolen time.
265 struct cpu_purr_data {
266 int initialized; /* thread is running */
267 u64 tb; /* last TB value read */
268 u64 purr; /* last PURR value read */
272 * Each entry in the cpu_purr_data array is manipulated only by its
273 * "owner" cpu -- usually in the timer interrupt but also occasionally
274 * in process context for cpu online. As long as cpus do not touch
275 * each others' cpu_purr_data, disabling local interrupts is
276 * sufficient to serialize accesses.
278 static DEFINE_PER_CPU(struct cpu_purr_data, cpu_purr_data);
280 static void snapshot_tb_and_purr(void *data)
283 struct cpu_purr_data *p = &__get_cpu_var(cpu_purr_data);
285 local_irq_save(flags);
286 p->tb = get_tb_or_rtc();
287 p->purr = mfspr(SPRN_PURR);
290 local_irq_restore(flags);
294 * Called during boot when all cpus have come up.
296 void snapshot_timebases(void)
298 if (!cpu_has_feature(CPU_FTR_PURR))
300 on_each_cpu(snapshot_tb_and_purr, NULL, 0, 1);
304 * Must be called with interrupts disabled.
306 void calculate_steal_time(void)
310 struct cpu_purr_data *pme;
312 if (!cpu_has_feature(CPU_FTR_PURR))
314 pme = &per_cpu(cpu_purr_data, smp_processor_id());
315 if (!pme->initialized)
316 return; /* this can happen in early boot */
318 purr = mfspr(SPRN_PURR);
319 stolen = (tb - pme->tb) - (purr - pme->purr);
321 account_steal_time(current, stolen);
326 #ifdef CONFIG_PPC_SPLPAR
328 * Must be called before the cpu is added to the online map when
329 * a cpu is being brought up at runtime.
331 static void snapshot_purr(void)
333 struct cpu_purr_data *pme;
336 if (!cpu_has_feature(CPU_FTR_PURR))
338 local_irq_save(flags);
339 pme = &per_cpu(cpu_purr_data, smp_processor_id());
341 pme->purr = mfspr(SPRN_PURR);
342 pme->initialized = 1;
343 local_irq_restore(flags);
346 #endif /* CONFIG_PPC_SPLPAR */
348 #else /* ! CONFIG_VIRT_CPU_ACCOUNTING */
349 #define calc_cputime_factors()
350 #define account_process_time(regs) update_process_times(user_mode(regs))
351 #define calculate_steal_time() do { } while (0)
354 #if !(defined(CONFIG_VIRT_CPU_ACCOUNTING) && defined(CONFIG_PPC_SPLPAR))
355 #define snapshot_purr() do { } while (0)
359 * Called when a cpu comes up after the system has finished booting,
360 * i.e. as a result of a hotplug cpu action.
362 void snapshot_timebase(void)
364 __get_cpu_var(last_jiffy) = get_tb_or_rtc();
368 void __delay(unsigned long loops)
376 /* the RTCL register wraps at 1000000000 */
377 diff = get_rtcl() - start;
380 } while (diff < loops);
383 while (get_tbl() - start < loops)
388 EXPORT_SYMBOL(__delay);
390 void udelay(unsigned long usecs)
392 __delay(tb_ticks_per_usec * usecs);
394 EXPORT_SYMBOL(udelay);
398 * There are two copies of tb_to_xs and stamp_xsec so that no
399 * lock is needed to access and use these values in
400 * do_gettimeofday. We alternate the copies and as long as a
401 * reasonable time elapses between changes, there will never
402 * be inconsistent values. ntpd has a minimum of one minute
405 static inline void update_gtod(u64 new_tb_stamp, u64 new_stamp_xsec,
409 struct gettimeofday_vars *temp_varp;
411 temp_idx = (do_gtod.var_idx == 0);
412 temp_varp = &do_gtod.vars[temp_idx];
414 temp_varp->tb_to_xs = new_tb_to_xs;
415 temp_varp->tb_orig_stamp = new_tb_stamp;
416 temp_varp->stamp_xsec = new_stamp_xsec;
418 do_gtod.varp = temp_varp;
419 do_gtod.var_idx = temp_idx;
422 * tb_update_count is used to allow the userspace gettimeofday code
423 * to assure itself that it sees a consistent view of the tb_to_xs and
424 * stamp_xsec variables. It reads the tb_update_count, then reads
425 * tb_to_xs and stamp_xsec and then reads tb_update_count again. If
426 * the two values of tb_update_count match and are even then the
427 * tb_to_xs and stamp_xsec values are consistent. If not, then it
428 * loops back and reads them again until this criteria is met.
429 * We expect the caller to have done the first increment of
430 * vdso_data->tb_update_count already.
432 vdso_data->tb_orig_stamp = new_tb_stamp;
433 vdso_data->stamp_xsec = new_stamp_xsec;
434 vdso_data->tb_to_xs = new_tb_to_xs;
435 vdso_data->wtom_clock_sec = wall_to_monotonic.tv_sec;
436 vdso_data->wtom_clock_nsec = wall_to_monotonic.tv_nsec;
438 ++(vdso_data->tb_update_count);
442 unsigned long profile_pc(struct pt_regs *regs)
444 unsigned long pc = instruction_pointer(regs);
446 if (in_lock_functions(pc))
451 EXPORT_SYMBOL(profile_pc);
454 #ifdef CONFIG_PPC_ISERIES
457 * This function recalibrates the timebase based on the 49-bit time-of-day
458 * value in the Titan chip. The Titan is much more accurate than the value
459 * returned by the service processor for the timebase frequency.
462 static int __init iSeries_tb_recal(void)
464 struct div_result divres;
465 unsigned long titan, tb;
467 /* Make sure we only run on iSeries */
468 if (!firmware_has_feature(FW_FEATURE_ISERIES))
472 titan = HvCallXm_loadTod();
473 if ( iSeries_recal_titan ) {
474 unsigned long tb_ticks = tb - iSeries_recal_tb;
475 unsigned long titan_usec = (titan - iSeries_recal_titan) >> 12;
476 unsigned long new_tb_ticks_per_sec = (tb_ticks * USEC_PER_SEC)/titan_usec;
477 unsigned long new_tb_ticks_per_jiffy = (new_tb_ticks_per_sec+(HZ/2))/HZ;
478 long tick_diff = new_tb_ticks_per_jiffy - tb_ticks_per_jiffy;
480 /* make sure tb_ticks_per_sec and tb_ticks_per_jiffy are consistent */
481 new_tb_ticks_per_sec = new_tb_ticks_per_jiffy * HZ;
483 if ( tick_diff < 0 ) {
484 tick_diff = -tick_diff;
488 if ( tick_diff < tb_ticks_per_jiffy/25 ) {
489 printk( "Titan recalibrate: new tb_ticks_per_jiffy = %lu (%c%ld)\n",
490 new_tb_ticks_per_jiffy, sign, tick_diff );
491 tb_ticks_per_jiffy = new_tb_ticks_per_jiffy;
492 tb_ticks_per_sec = new_tb_ticks_per_sec;
493 calc_cputime_factors();
494 div128_by_32( XSEC_PER_SEC, 0, tb_ticks_per_sec, &divres );
495 do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
496 tb_to_xs = divres.result_low;
497 do_gtod.varp->tb_to_xs = tb_to_xs;
498 vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
499 vdso_data->tb_to_xs = tb_to_xs;
502 printk( "Titan recalibrate: FAILED (difference > 4 percent)\n"
503 " new tb_ticks_per_jiffy = %lu\n"
504 " old tb_ticks_per_jiffy = %lu\n",
505 new_tb_ticks_per_jiffy, tb_ticks_per_jiffy );
509 iSeries_recal_titan = titan;
510 iSeries_recal_tb = tb;
512 /* Called here as now we know accurate values for the timebase */
516 late_initcall(iSeries_tb_recal);
518 /* Called from platform early init */
519 void __init iSeries_time_init_early(void)
521 iSeries_recal_tb = get_tb();
522 iSeries_recal_titan = HvCallXm_loadTod();
524 #endif /* CONFIG_PPC_ISERIES */
527 * For iSeries shared processors, we have to let the hypervisor
528 * set the hardware decrementer. We set a virtual decrementer
529 * in the lppaca and call the hypervisor if the virtual
530 * decrementer is less than the current value in the hardware
531 * decrementer. (almost always the new decrementer value will
532 * be greater than the current hardware decementer so the hypervisor
533 * call will not be needed)
537 * timer_interrupt - gets called when the decrementer overflows,
538 * with interrupts disabled.
540 void timer_interrupt(struct pt_regs * regs)
542 struct pt_regs *old_regs;
543 int cpu = smp_processor_id();
544 struct clock_event_device *evt = &per_cpu(decrementers, cpu);
547 /* Ensure a positive value is written to the decrementer, or else
548 * some CPUs will continuue to take decrementer exceptions */
549 set_dec(DECREMENTER_MAX);
552 if (atomic_read(&ppc_n_lost_interrupts) != 0)
556 now = get_tb_or_rtc();
557 if (now < per_cpu(decrementer_next_tb, cpu)) {
558 /* not time for this event yet */
559 now = per_cpu(decrementer_next_tb, cpu) - now;
560 if (now <= DECREMENTER_MAX)
561 set_dec((unsigned int)now - 1);
564 old_regs = set_irq_regs(regs);
567 calculate_steal_time();
569 #ifdef CONFIG_PPC_ISERIES
570 if (firmware_has_feature(FW_FEATURE_ISERIES))
571 get_lppaca()->int_dword.fields.decr_int = 0;
575 * We cannot disable the decrementer, so in the period
576 * between this cpu's being marked offline in cpu_online_map
577 * and calling stop-self, it is taking timer interrupts.
578 * Avoid calling into the scheduler rebalancing code if this
581 if (!cpu_is_offline(cpu))
582 account_process_time(regs);
584 if (evt->event_handler)
585 evt->event_handler(evt);
587 evt->set_next_event(DECREMENTER_MAX, evt);
589 #ifdef CONFIG_PPC_ISERIES
590 if (firmware_has_feature(FW_FEATURE_ISERIES) && hvlpevent_is_pending())
591 process_hvlpevents();
595 /* collect purr register values often, for accurate calculations */
596 if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
597 struct cpu_usage *cu = &__get_cpu_var(cpu_usage_array);
598 cu->current_tb = mfspr(SPRN_PURR);
603 set_irq_regs(old_regs);
606 void wakeup_decrementer(void)
611 * The timebase gets saved on sleep and restored on wakeup,
612 * so all we need to do is to reset the decrementer.
614 ticks = tb_ticks_since(__get_cpu_var(last_jiffy));
615 if (ticks < tb_ticks_per_jiffy)
616 ticks = tb_ticks_per_jiffy - ticks;
623 void __init smp_space_timers(unsigned int max_cpus)
626 u64 previous_tb = per_cpu(last_jiffy, boot_cpuid);
628 /* make sure tb > per_cpu(last_jiffy, cpu) for all cpus always */
629 previous_tb -= tb_ticks_per_jiffy;
631 for_each_possible_cpu(i) {
634 per_cpu(last_jiffy, i) = previous_tb;
640 * Scheduler clock - returns current time in nanosec units.
642 * Note: mulhdu(a, b) (multiply high double unsigned) returns
643 * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
644 * are 64-bit unsigned numbers.
646 unsigned long long sched_clock(void)
650 return mulhdu(get_tb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
653 static int __init get_freq(char *name, int cells, unsigned long *val)
655 struct device_node *cpu;
656 const unsigned int *fp;
659 /* The cpu node should have timebase and clock frequency properties */
660 cpu = of_find_node_by_type(NULL, "cpu");
663 fp = of_get_property(cpu, name, NULL);
666 *val = of_read_ulong(fp, cells);
675 void __init generic_calibrate_decr(void)
677 ppc_tb_freq = DEFAULT_TB_FREQ; /* hardcoded default */
679 if (!get_freq("ibm,extended-timebase-frequency", 2, &ppc_tb_freq) &&
680 !get_freq("timebase-frequency", 1, &ppc_tb_freq)) {
682 printk(KERN_ERR "WARNING: Estimating decrementer frequency "
686 ppc_proc_freq = DEFAULT_PROC_FREQ; /* hardcoded default */
688 if (!get_freq("ibm,extended-clock-frequency", 2, &ppc_proc_freq) &&
689 !get_freq("clock-frequency", 1, &ppc_proc_freq)) {
691 printk(KERN_ERR "WARNING: Estimating processor frequency "
695 #if defined(CONFIG_BOOKE) || defined(CONFIG_40x)
696 /* Set the time base to zero */
700 /* Clear any pending timer interrupts */
701 mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS);
703 /* Enable decrementer interrupt */
704 mtspr(SPRN_TCR, TCR_DIE);
708 int update_persistent_clock(struct timespec now)
712 if (!ppc_md.set_rtc_time)
715 to_tm(now.tv_sec + 1 + timezone_offset, &tm);
719 return ppc_md.set_rtc_time(&tm);
722 unsigned long read_persistent_clock(void)
725 static int first = 1;
727 /* XXX this is a litle fragile but will work okay in the short term */
730 if (ppc_md.time_init)
731 timezone_offset = ppc_md.time_init();
733 /* get_boot_time() isn't guaranteed to be safe to call late */
734 if (ppc_md.get_boot_time)
735 return ppc_md.get_boot_time() -timezone_offset;
737 if (!ppc_md.get_rtc_time)
739 ppc_md.get_rtc_time(&tm);
740 return mktime(tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday,
741 tm.tm_hour, tm.tm_min, tm.tm_sec);
744 /* clocksource code */
745 static cycle_t rtc_read(void)
747 return (cycle_t)get_rtc();
750 static cycle_t timebase_read(void)
752 return (cycle_t)get_tb();
755 void update_vsyscall(struct timespec *wall_time, struct clocksource *clock)
759 if (clock != &clocksource_timebase)
762 /* Make userspace gettimeofday spin until we're done. */
763 ++vdso_data->tb_update_count;
766 /* XXX this assumes clock->shift == 22 */
767 /* 4611686018 ~= 2^(20+64-22) / 1e9 */
768 t2x = (u64) clock->mult * 4611686018ULL;
769 stamp_xsec = (u64) xtime.tv_nsec * XSEC_PER_SEC;
770 do_div(stamp_xsec, 1000000000);
771 stamp_xsec += (u64) xtime.tv_sec * XSEC_PER_SEC;
772 update_gtod(clock->cycle_last, stamp_xsec, t2x);
775 void update_vsyscall_tz(void)
777 /* Make userspace gettimeofday spin until we're done. */
778 ++vdso_data->tb_update_count;
780 vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
781 vdso_data->tz_dsttime = sys_tz.tz_dsttime;
783 ++vdso_data->tb_update_count;
786 void __init clocksource_init(void)
788 struct clocksource *clock;
791 clock = &clocksource_rtc;
793 clock = &clocksource_timebase;
795 clock->mult = clocksource_hz2mult(tb_ticks_per_sec, clock->shift);
797 if (clocksource_register(clock)) {
798 printk(KERN_ERR "clocksource: %s is already registered\n",
803 printk(KERN_INFO "clocksource: %s mult[%x] shift[%d] registered\n",
804 clock->name, clock->mult, clock->shift);
807 static int decrementer_set_next_event(unsigned long evt,
808 struct clock_event_device *dev)
810 __get_cpu_var(decrementer_next_tb) = get_tb_or_rtc() + evt;
811 /* The decrementer interrupts on the 0 -> -1 transition */
818 static void decrementer_set_mode(enum clock_event_mode mode,
819 struct clock_event_device *dev)
821 if (mode != CLOCK_EVT_MODE_ONESHOT)
822 decrementer_set_next_event(DECREMENTER_MAX, dev);
825 static void register_decrementer_clockevent(int cpu)
827 struct clock_event_device *dec = &per_cpu(decrementers, cpu);
829 *dec = decrementer_clockevent;
830 dec->cpumask = cpumask_of_cpu(cpu);
832 printk(KERN_ERR "clockevent: %s mult[%lx] shift[%d] cpu[%d]\n",
833 dec->name, dec->mult, dec->shift, cpu);
835 clockevents_register_device(dec);
838 void init_decrementer_clockevent(void)
840 int cpu = smp_processor_id();
842 decrementer_clockevent.mult = div_sc(ppc_tb_freq, NSEC_PER_SEC,
843 decrementer_clockevent.shift);
844 decrementer_clockevent.max_delta_ns =
845 clockevent_delta2ns(DECREMENTER_MAX, &decrementer_clockevent);
846 decrementer_clockevent.min_delta_ns = 1000;
848 register_decrementer_clockevent(cpu);
851 void secondary_cpu_time_init(void)
853 /* FIME: Should make unrelatred change to move snapshot_timebase
855 register_decrementer_clockevent(smp_processor_id());
858 /* This function is only called on the boot processor */
859 void __init time_init(void)
862 struct div_result res;
867 /* 601 processor: dec counts down by 128 every 128ns */
868 ppc_tb_freq = 1000000000;
869 tb_last_jiffy = get_rtcl();
871 /* Normal PowerPC with timebase register */
872 ppc_md.calibrate_decr();
873 printk(KERN_DEBUG "time_init: decrementer frequency = %lu.%.6lu MHz\n",
874 ppc_tb_freq / 1000000, ppc_tb_freq % 1000000);
875 printk(KERN_DEBUG "time_init: processor frequency = %lu.%.6lu MHz\n",
876 ppc_proc_freq / 1000000, ppc_proc_freq % 1000000);
877 tb_last_jiffy = get_tb();
880 tb_ticks_per_jiffy = ppc_tb_freq / HZ;
881 tb_ticks_per_sec = ppc_tb_freq;
882 tb_ticks_per_usec = ppc_tb_freq / 1000000;
883 tb_to_us = mulhwu_scale_factor(ppc_tb_freq, 1000000);
884 calc_cputime_factors();
887 * Calculate the length of each tick in ns. It will not be
888 * exactly 1e9/HZ unless ppc_tb_freq is divisible by HZ.
889 * We compute 1e9 * tb_ticks_per_jiffy / ppc_tb_freq,
892 x = (u64) NSEC_PER_SEC * tb_ticks_per_jiffy + ppc_tb_freq - 1;
893 do_div(x, ppc_tb_freq);
895 last_tick_len = x << TICKLEN_SCALE;
898 * Compute ticklen_to_xs, which is a factor which gets multiplied
899 * by (last_tick_len << TICKLEN_SHIFT) to get a tb_to_xs value.
901 * ticklen_to_xs = 2^N / (tb_ticks_per_jiffy * 1e9)
902 * where N = 64 + 20 - TICKLEN_SCALE - TICKLEN_SHIFT
903 * which turns out to be N = 51 - SHIFT_HZ.
904 * This gives the result as a 0.64 fixed-point fraction.
905 * That value is reduced by an offset amounting to 1 xsec per
906 * 2^31 timebase ticks to avoid problems with time going backwards
907 * by 1 xsec when we do timer_recalc_offset due to losing the
908 * fractional xsec. That offset is equal to ppc_tb_freq/2^51
909 * since there are 2^20 xsec in a second.
911 div128_by_32((1ULL << 51) - ppc_tb_freq, 0,
912 tb_ticks_per_jiffy << SHIFT_HZ, &res);
913 div128_by_32(res.result_high, res.result_low, NSEC_PER_SEC, &res);
914 ticklen_to_xs = res.result_low;
916 /* Compute tb_to_xs from tick_nsec */
917 tb_to_xs = mulhdu(last_tick_len << TICKLEN_SHIFT, ticklen_to_xs);
920 * Compute scale factor for sched_clock.
921 * The calibrate_decr() function has set tb_ticks_per_sec,
922 * which is the timebase frequency.
923 * We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
924 * the 128-bit result as a 64.64 fixed-point number.
925 * We then shift that number right until it is less than 1.0,
926 * giving us the scale factor and shift count to use in
929 div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
930 scale = res.result_low;
931 for (shift = 0; res.result_high != 0; ++shift) {
932 scale = (scale >> 1) | (res.result_high << 63);
933 res.result_high >>= 1;
935 tb_to_ns_scale = scale;
936 tb_to_ns_shift = shift;
937 /* Save the current timebase to pretty up CONFIG_PRINTK_TIME */
938 boot_tb = get_tb_or_rtc();
940 write_seqlock_irqsave(&xtime_lock, flags);
942 /* If platform provided a timezone (pmac), we correct the time */
943 if (timezone_offset) {
944 sys_tz.tz_minuteswest = -timezone_offset / 60;
945 sys_tz.tz_dsttime = 0;
948 do_gtod.varp = &do_gtod.vars[0];
950 do_gtod.varp->tb_orig_stamp = tb_last_jiffy;
951 __get_cpu_var(last_jiffy) = tb_last_jiffy;
952 do_gtod.varp->stamp_xsec = (u64) xtime.tv_sec * XSEC_PER_SEC;
953 do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
954 do_gtod.varp->tb_to_xs = tb_to_xs;
955 do_gtod.tb_to_us = tb_to_us;
957 vdso_data->tb_orig_stamp = tb_last_jiffy;
958 vdso_data->tb_update_count = 0;
959 vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
960 vdso_data->stamp_xsec = (u64) xtime.tv_sec * XSEC_PER_SEC;
961 vdso_data->tb_to_xs = tb_to_xs;
965 write_sequnlock_irqrestore(&xtime_lock, flags);
967 /* Register the clocksource, if we're not running on iSeries */
968 if (!firmware_has_feature(FW_FEATURE_ISERIES))
971 init_decrementer_clockevent();
976 #define STARTOFTIME 1970
977 #define SECDAY 86400L
978 #define SECYR (SECDAY * 365)
979 #define leapyear(year) ((year) % 4 == 0 && \
980 ((year) % 100 != 0 || (year) % 400 == 0))
981 #define days_in_year(a) (leapyear(a) ? 366 : 365)
982 #define days_in_month(a) (month_days[(a) - 1])
984 static int month_days[12] = {
985 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
989 * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
991 void GregorianDay(struct rtc_time * tm)
996 int MonthOffset[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
998 lastYear = tm->tm_year - 1;
1001 * Number of leap corrections to apply up to end of last year
1003 leapsToDate = lastYear / 4 - lastYear / 100 + lastYear / 400;
1006 * This year is a leap year if it is divisible by 4 except when it is
1007 * divisible by 100 unless it is divisible by 400
1009 * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 was
1011 day = tm->tm_mon > 2 && leapyear(tm->tm_year);
1013 day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] +
1016 tm->tm_wday = day % 7;
1019 void to_tm(int tim, struct rtc_time * tm)
1022 register long hms, day;
1027 /* Hours, minutes, seconds are easy */
1028 tm->tm_hour = hms / 3600;
1029 tm->tm_min = (hms % 3600) / 60;
1030 tm->tm_sec = (hms % 3600) % 60;
1032 /* Number of years in days */
1033 for (i = STARTOFTIME; day >= days_in_year(i); i++)
1034 day -= days_in_year(i);
1037 /* Number of months in days left */
1038 if (leapyear(tm->tm_year))
1039 days_in_month(FEBRUARY) = 29;
1040 for (i = 1; day >= days_in_month(i); i++)
1041 day -= days_in_month(i);
1042 days_in_month(FEBRUARY) = 28;
1045 /* Days are what is left over (+1) from all that. */
1046 tm->tm_mday = day + 1;
1049 * Determine the day of week
1054 /* Auxiliary function to compute scaling factors */
1055 /* Actually the choice of a timebase running at 1/4 the of the bus
1056 * frequency giving resolution of a few tens of nanoseconds is quite nice.
1057 * It makes this computation very precise (27-28 bits typically) which
1058 * is optimistic considering the stability of most processor clock
1059 * oscillators and the precision with which the timebase frequency
1060 * is measured but does not harm.
1062 unsigned mulhwu_scale_factor(unsigned inscale, unsigned outscale)
1064 unsigned mlt=0, tmp, err;
1065 /* No concern for performance, it's done once: use a stupid
1066 * but safe and compact method to find the multiplier.
1069 for (tmp = 1U<<31; tmp != 0; tmp >>= 1) {
1070 if (mulhwu(inscale, mlt|tmp) < outscale)
1074 /* We might still be off by 1 for the best approximation.
1075 * A side effect of this is that if outscale is too large
1076 * the returned value will be zero.
1077 * Many corner cases have been checked and seem to work,
1078 * some might have been forgotten in the test however.
1081 err = inscale * (mlt+1);
1082 if (err <= inscale/2)
1088 * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
1091 void div128_by_32(u64 dividend_high, u64 dividend_low,
1092 unsigned divisor, struct div_result *dr)
1094 unsigned long a, b, c, d;
1095 unsigned long w, x, y, z;
1098 a = dividend_high >> 32;
1099 b = dividend_high & 0xffffffff;
1100 c = dividend_low >> 32;
1101 d = dividend_low & 0xffffffff;
1104 ra = ((u64)(a - (w * divisor)) << 32) + b;
1106 rb = ((u64) do_div(ra, divisor) << 32) + c;
1109 rc = ((u64) do_div(rb, divisor) << 32) + d;
1112 do_div(rc, divisor);
1115 dr->result_high = ((u64)w << 32) + x;
1116 dr->result_low = ((u64)y << 32) + z;