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>
55 #include <linux/delay.h>
56 #include <linux/perf_event.h>
59 #include <asm/processor.h>
60 #include <asm/nvram.h>
61 #include <asm/cache.h>
62 #include <asm/machdep.h>
63 #include <asm/uaccess.h>
67 #include <asm/div64.h>
69 #include <asm/vdso_datapage.h>
70 #include <asm/firmware.h>
71 #include <asm/cputime.h>
72 #ifdef CONFIG_PPC_ISERIES
73 #include <asm/iseries/it_lp_queue.h>
74 #include <asm/iseries/hv_call_xm.h>
77 /* powerpc clocksource/clockevent code */
79 #include <linux/clockchips.h>
80 #include <linux/clocksource.h>
82 static cycle_t rtc_read(struct clocksource *);
83 static struct clocksource clocksource_rtc = {
86 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
87 .mask = CLOCKSOURCE_MASK(64),
89 .mult = 0, /* To be filled in */
93 static cycle_t timebase_read(struct clocksource *);
94 static struct clocksource clocksource_timebase = {
97 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
98 .mask = CLOCKSOURCE_MASK(64),
100 .mult = 0, /* To be filled in */
101 .read = timebase_read,
104 #define DECREMENTER_MAX 0x7fffffff
106 static int decrementer_set_next_event(unsigned long evt,
107 struct clock_event_device *dev);
108 static void decrementer_set_mode(enum clock_event_mode mode,
109 struct clock_event_device *dev);
111 static struct clock_event_device decrementer_clockevent = {
112 .name = "decrementer",
114 .shift = 0, /* To be filled in */
115 .mult = 0, /* To be filled in */
117 .set_next_event = decrementer_set_next_event,
118 .set_mode = decrementer_set_mode,
119 .features = CLOCK_EVT_FEAT_ONESHOT,
122 struct decrementer_clock {
123 struct clock_event_device event;
127 static DEFINE_PER_CPU(struct decrementer_clock, decrementers);
129 #ifdef CONFIG_PPC_ISERIES
130 static unsigned long __initdata iSeries_recal_titan;
131 static signed long __initdata iSeries_recal_tb;
133 /* Forward declaration is only needed for iSereis compiles */
134 static void __init clocksource_init(void);
137 #define XSEC_PER_SEC (1024*1024)
140 #define SCALE_XSEC(xsec, max) (((xsec) * max) / XSEC_PER_SEC)
142 /* compute ((xsec << 12) * max) >> 32 */
143 #define SCALE_XSEC(xsec, max) mulhwu((xsec) << 12, max)
146 unsigned long tb_ticks_per_jiffy;
147 unsigned long tb_ticks_per_usec = 100; /* sane default */
148 EXPORT_SYMBOL(tb_ticks_per_usec);
149 unsigned long tb_ticks_per_sec;
150 EXPORT_SYMBOL(tb_ticks_per_sec); /* for cputime_t conversions */
154 #define TICKLEN_SCALE NTP_SCALE_SHIFT
155 static u64 last_tick_len; /* units are ns / 2^TICKLEN_SCALE */
156 static u64 ticklen_to_xs; /* 0.64 fraction */
158 /* If last_tick_len corresponds to about 1/HZ seconds, then
159 last_tick_len << TICKLEN_SHIFT will be about 2^63. */
160 #define TICKLEN_SHIFT (63 - 30 - TICKLEN_SCALE + SHIFT_HZ)
162 DEFINE_SPINLOCK(rtc_lock);
163 EXPORT_SYMBOL_GPL(rtc_lock);
165 static u64 tb_to_ns_scale __read_mostly;
166 static unsigned tb_to_ns_shift __read_mostly;
167 static unsigned long boot_tb __read_mostly;
169 extern struct timezone sys_tz;
170 static long timezone_offset;
172 unsigned long ppc_proc_freq;
173 EXPORT_SYMBOL(ppc_proc_freq);
174 unsigned long ppc_tb_freq;
176 static u64 tb_last_jiffy __cacheline_aligned_in_smp;
177 static DEFINE_PER_CPU(u64, last_jiffy);
179 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
181 * Factors for converting from cputime_t (timebase ticks) to
182 * jiffies, milliseconds, seconds, and clock_t (1/USER_HZ seconds).
183 * These are all stored as 0.64 fixed-point binary fractions.
185 u64 __cputime_jiffies_factor;
186 EXPORT_SYMBOL(__cputime_jiffies_factor);
187 u64 __cputime_msec_factor;
188 EXPORT_SYMBOL(__cputime_msec_factor);
189 u64 __cputime_sec_factor;
190 EXPORT_SYMBOL(__cputime_sec_factor);
191 u64 __cputime_clockt_factor;
192 EXPORT_SYMBOL(__cputime_clockt_factor);
193 DEFINE_PER_CPU(unsigned long, cputime_last_delta);
194 DEFINE_PER_CPU(unsigned long, cputime_scaled_last_delta);
196 static void calc_cputime_factors(void)
198 struct div_result res;
200 div128_by_32(HZ, 0, tb_ticks_per_sec, &res);
201 __cputime_jiffies_factor = res.result_low;
202 div128_by_32(1000, 0, tb_ticks_per_sec, &res);
203 __cputime_msec_factor = res.result_low;
204 div128_by_32(1, 0, tb_ticks_per_sec, &res);
205 __cputime_sec_factor = res.result_low;
206 div128_by_32(USER_HZ, 0, tb_ticks_per_sec, &res);
207 __cputime_clockt_factor = res.result_low;
211 * Read the PURR on systems that have it, otherwise the timebase.
213 static u64 read_purr(void)
215 if (cpu_has_feature(CPU_FTR_PURR))
216 return mfspr(SPRN_PURR);
221 * Read the SPURR on systems that have it, otherwise the purr
223 static u64 read_spurr(u64 purr)
226 * cpus without PURR won't have a SPURR
227 * We already know the former when we use this, so tell gcc
229 if (cpu_has_feature(CPU_FTR_PURR) && cpu_has_feature(CPU_FTR_SPURR))
230 return mfspr(SPRN_SPURR);
235 * Account time for a transition between system, hard irq
238 void account_system_vtime(struct task_struct *tsk)
240 u64 now, nowscaled, delta, deltascaled, sys_time;
243 local_irq_save(flags);
245 nowscaled = read_spurr(now);
246 delta = now - get_paca()->startpurr;
247 deltascaled = nowscaled - get_paca()->startspurr;
248 get_paca()->startpurr = now;
249 get_paca()->startspurr = nowscaled;
250 if (!in_interrupt()) {
251 /* deltascaled includes both user and system time.
252 * Hence scale it based on the purr ratio to estimate
254 sys_time = get_paca()->system_time;
255 if (get_paca()->user_time)
256 deltascaled = deltascaled * sys_time /
257 (sys_time + get_paca()->user_time);
259 get_paca()->system_time = 0;
261 if (in_irq() || idle_task(smp_processor_id()) != tsk)
262 account_system_time(tsk, 0, delta, deltascaled);
264 account_idle_time(delta);
265 per_cpu(cputime_last_delta, smp_processor_id()) = delta;
266 per_cpu(cputime_scaled_last_delta, smp_processor_id()) = deltascaled;
267 local_irq_restore(flags);
271 * Transfer the user and system times accumulated in the paca
272 * by the exception entry and exit code to the generic process
273 * user and system time records.
274 * Must be called with interrupts disabled.
276 void account_process_tick(struct task_struct *tsk, int user_tick)
278 cputime_t utime, utimescaled;
280 utime = get_paca()->user_time;
281 get_paca()->user_time = 0;
282 utimescaled = cputime_to_scaled(utime);
283 account_user_time(tsk, utime, utimescaled);
287 * Stuff for accounting stolen time.
289 struct cpu_purr_data {
290 int initialized; /* thread is running */
291 u64 tb; /* last TB value read */
292 u64 purr; /* last PURR value read */
293 u64 spurr; /* last SPURR value read */
297 * Each entry in the cpu_purr_data array is manipulated only by its
298 * "owner" cpu -- usually in the timer interrupt but also occasionally
299 * in process context for cpu online. As long as cpus do not touch
300 * each others' cpu_purr_data, disabling local interrupts is
301 * sufficient to serialize accesses.
303 static DEFINE_PER_CPU(struct cpu_purr_data, cpu_purr_data);
305 static void snapshot_tb_and_purr(void *data)
308 struct cpu_purr_data *p = &__get_cpu_var(cpu_purr_data);
310 local_irq_save(flags);
311 p->tb = get_tb_or_rtc();
312 p->purr = mfspr(SPRN_PURR);
315 local_irq_restore(flags);
319 * Called during boot when all cpus have come up.
321 void snapshot_timebases(void)
323 if (!cpu_has_feature(CPU_FTR_PURR))
325 on_each_cpu(snapshot_tb_and_purr, NULL, 1);
329 * Must be called with interrupts disabled.
331 void calculate_steal_time(void)
335 struct cpu_purr_data *pme;
337 pme = &__get_cpu_var(cpu_purr_data);
338 if (!pme->initialized)
339 return; /* !CPU_FTR_PURR or early in early boot */
341 purr = mfspr(SPRN_PURR);
342 stolen = (tb - pme->tb) - (purr - pme->purr);
344 if (idle_task(smp_processor_id()) != current)
345 account_steal_time(stolen);
347 account_idle_time(stolen);
353 #ifdef CONFIG_PPC_SPLPAR
355 * Must be called before the cpu is added to the online map when
356 * a cpu is being brought up at runtime.
358 static void snapshot_purr(void)
360 struct cpu_purr_data *pme;
363 if (!cpu_has_feature(CPU_FTR_PURR))
365 local_irq_save(flags);
366 pme = &__get_cpu_var(cpu_purr_data);
368 pme->purr = mfspr(SPRN_PURR);
369 pme->initialized = 1;
370 local_irq_restore(flags);
373 #endif /* CONFIG_PPC_SPLPAR */
375 #else /* ! CONFIG_VIRT_CPU_ACCOUNTING */
376 #define calc_cputime_factors()
377 #define calculate_steal_time() do { } while (0)
380 #if !(defined(CONFIG_VIRT_CPU_ACCOUNTING) && defined(CONFIG_PPC_SPLPAR))
381 #define snapshot_purr() do { } while (0)
385 * Called when a cpu comes up after the system has finished booting,
386 * i.e. as a result of a hotplug cpu action.
388 void snapshot_timebase(void)
390 __get_cpu_var(last_jiffy) = get_tb_or_rtc();
394 void __delay(unsigned long loops)
402 /* the RTCL register wraps at 1000000000 */
403 diff = get_rtcl() - start;
406 } while (diff < loops);
409 while (get_tbl() - start < loops)
414 EXPORT_SYMBOL(__delay);
416 void udelay(unsigned long usecs)
418 __delay(tb_ticks_per_usec * usecs);
420 EXPORT_SYMBOL(udelay);
422 static inline void update_gtod(u64 new_tb_stamp, u64 new_stamp_xsec,
426 * tb_update_count is used to allow the userspace gettimeofday code
427 * to assure itself that it sees a consistent view of the tb_to_xs and
428 * stamp_xsec variables. It reads the tb_update_count, then reads
429 * tb_to_xs and stamp_xsec and then reads tb_update_count again. If
430 * the two values of tb_update_count match and are even then the
431 * tb_to_xs and stamp_xsec values are consistent. If not, then it
432 * loops back and reads them again until this criteria is met.
433 * We expect the caller to have done the first increment of
434 * vdso_data->tb_update_count already.
436 vdso_data->tb_orig_stamp = new_tb_stamp;
437 vdso_data->stamp_xsec = new_stamp_xsec;
438 vdso_data->tb_to_xs = new_tb_to_xs;
439 vdso_data->wtom_clock_sec = wall_to_monotonic.tv_sec;
440 vdso_data->wtom_clock_nsec = wall_to_monotonic.tv_nsec;
441 vdso_data->stamp_xtime = xtime;
443 ++(vdso_data->tb_update_count);
447 unsigned long profile_pc(struct pt_regs *regs)
449 unsigned long pc = instruction_pointer(regs);
451 if (in_lock_functions(pc))
456 EXPORT_SYMBOL(profile_pc);
459 #ifdef CONFIG_PPC_ISERIES
462 * This function recalibrates the timebase based on the 49-bit time-of-day
463 * value in the Titan chip. The Titan is much more accurate than the value
464 * returned by the service processor for the timebase frequency.
467 static int __init iSeries_tb_recal(void)
469 struct div_result divres;
470 unsigned long titan, tb;
472 /* Make sure we only run on iSeries */
473 if (!firmware_has_feature(FW_FEATURE_ISERIES))
477 titan = HvCallXm_loadTod();
478 if ( iSeries_recal_titan ) {
479 unsigned long tb_ticks = tb - iSeries_recal_tb;
480 unsigned long titan_usec = (titan - iSeries_recal_titan) >> 12;
481 unsigned long new_tb_ticks_per_sec = (tb_ticks * USEC_PER_SEC)/titan_usec;
482 unsigned long new_tb_ticks_per_jiffy =
483 DIV_ROUND_CLOSEST(new_tb_ticks_per_sec, HZ);
484 long tick_diff = new_tb_ticks_per_jiffy - tb_ticks_per_jiffy;
486 /* make sure tb_ticks_per_sec and tb_ticks_per_jiffy are consistent */
487 new_tb_ticks_per_sec = new_tb_ticks_per_jiffy * HZ;
489 if ( tick_diff < 0 ) {
490 tick_diff = -tick_diff;
494 if ( tick_diff < tb_ticks_per_jiffy/25 ) {
495 printk( "Titan recalibrate: new tb_ticks_per_jiffy = %lu (%c%ld)\n",
496 new_tb_ticks_per_jiffy, sign, tick_diff );
497 tb_ticks_per_jiffy = new_tb_ticks_per_jiffy;
498 tb_ticks_per_sec = new_tb_ticks_per_sec;
499 calc_cputime_factors();
500 div128_by_32( XSEC_PER_SEC, 0, tb_ticks_per_sec, &divres );
501 tb_to_xs = divres.result_low;
502 vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
503 vdso_data->tb_to_xs = tb_to_xs;
506 printk( "Titan recalibrate: FAILED (difference > 4 percent)\n"
507 " new tb_ticks_per_jiffy = %lu\n"
508 " old tb_ticks_per_jiffy = %lu\n",
509 new_tb_ticks_per_jiffy, tb_ticks_per_jiffy );
513 iSeries_recal_titan = titan;
514 iSeries_recal_tb = tb;
516 /* Called here as now we know accurate values for the timebase */
520 late_initcall(iSeries_tb_recal);
522 /* Called from platform early init */
523 void __init iSeries_time_init_early(void)
525 iSeries_recal_tb = get_tb();
526 iSeries_recal_titan = HvCallXm_loadTod();
528 #endif /* CONFIG_PPC_ISERIES */
530 #if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_PPC32)
531 DEFINE_PER_CPU(u8, perf_event_pending);
533 void set_perf_event_pending(void)
535 get_cpu_var(perf_event_pending) = 1;
537 put_cpu_var(perf_event_pending);
540 #define test_perf_event_pending() __get_cpu_var(perf_event_pending)
541 #define clear_perf_event_pending() __get_cpu_var(perf_event_pending) = 0
543 #else /* CONFIG_PERF_EVENTS && CONFIG_PPC32 */
545 #define test_perf_event_pending() 0
546 #define clear_perf_event_pending()
548 #endif /* CONFIG_PERF_EVENTS && CONFIG_PPC32 */
551 * For iSeries shared processors, we have to let the hypervisor
552 * set the hardware decrementer. We set a virtual decrementer
553 * in the lppaca and call the hypervisor if the virtual
554 * decrementer is less than the current value in the hardware
555 * decrementer. (almost always the new decrementer value will
556 * be greater than the current hardware decementer so the hypervisor
557 * call will not be needed)
561 * timer_interrupt - gets called when the decrementer overflows,
562 * with interrupts disabled.
564 void timer_interrupt(struct pt_regs * regs)
566 struct pt_regs *old_regs;
567 struct decrementer_clock *decrementer = &__get_cpu_var(decrementers);
568 struct clock_event_device *evt = &decrementer->event;
571 /* Ensure a positive value is written to the decrementer, or else
572 * some CPUs will continuue to take decrementer exceptions */
573 set_dec(DECREMENTER_MAX);
576 if (test_perf_event_pending()) {
577 clear_perf_event_pending();
578 perf_event_do_pending();
580 if (atomic_read(&ppc_n_lost_interrupts) != 0)
584 now = get_tb_or_rtc();
585 if (now < decrementer->next_tb) {
586 /* not time for this event yet */
587 now = decrementer->next_tb - now;
588 if (now <= DECREMENTER_MAX)
592 old_regs = set_irq_regs(regs);
595 calculate_steal_time();
597 #ifdef CONFIG_PPC_ISERIES
598 if (firmware_has_feature(FW_FEATURE_ISERIES))
599 get_lppaca()->int_dword.fields.decr_int = 0;
602 if (evt->event_handler)
603 evt->event_handler(evt);
605 #ifdef CONFIG_PPC_ISERIES
606 if (firmware_has_feature(FW_FEATURE_ISERIES) && hvlpevent_is_pending())
607 process_hvlpevents();
611 /* collect purr register values often, for accurate calculations */
612 if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
613 struct cpu_usage *cu = &__get_cpu_var(cpu_usage_array);
614 cu->current_tb = mfspr(SPRN_PURR);
619 set_irq_regs(old_regs);
622 void wakeup_decrementer(void)
627 * The timebase gets saved on sleep and restored on wakeup,
628 * so all we need to do is to reset the decrementer.
630 ticks = tb_ticks_since(__get_cpu_var(last_jiffy));
631 if (ticks < tb_ticks_per_jiffy)
632 ticks = tb_ticks_per_jiffy - ticks;
638 #ifdef CONFIG_SUSPEND
639 void generic_suspend_disable_irqs(void)
643 /* Disable the decrementer, so that it doesn't interfere
652 void generic_suspend_enable_irqs(void)
654 wakeup_decrementer();
660 /* Overrides the weak version in kernel/power/main.c */
661 void arch_suspend_disable_irqs(void)
663 if (ppc_md.suspend_disable_irqs)
664 ppc_md.suspend_disable_irqs();
665 generic_suspend_disable_irqs();
668 /* Overrides the weak version in kernel/power/main.c */
669 void arch_suspend_enable_irqs(void)
671 generic_suspend_enable_irqs();
672 if (ppc_md.suspend_enable_irqs)
673 ppc_md.suspend_enable_irqs();
678 void __init smp_space_timers(unsigned int max_cpus)
681 u64 previous_tb = per_cpu(last_jiffy, boot_cpuid);
683 /* make sure tb > per_cpu(last_jiffy, cpu) for all cpus always */
684 previous_tb -= tb_ticks_per_jiffy;
686 for_each_possible_cpu(i) {
689 per_cpu(last_jiffy, i) = previous_tb;
695 * Scheduler clock - returns current time in nanosec units.
697 * Note: mulhdu(a, b) (multiply high double unsigned) returns
698 * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
699 * are 64-bit unsigned numbers.
701 unsigned long long sched_clock(void)
705 return mulhdu(get_tb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
708 static int __init get_freq(char *name, int cells, unsigned long *val)
710 struct device_node *cpu;
711 const unsigned int *fp;
714 /* The cpu node should have timebase and clock frequency properties */
715 cpu = of_find_node_by_type(NULL, "cpu");
718 fp = of_get_property(cpu, name, NULL);
721 *val = of_read_ulong(fp, cells);
730 /* should become __cpuinit when secondary_cpu_time_init also is */
731 void start_cpu_decrementer(void)
733 #if defined(CONFIG_BOOKE) || defined(CONFIG_40x)
734 /* Clear any pending timer interrupts */
735 mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS);
737 /* Enable decrementer interrupt */
738 mtspr(SPRN_TCR, TCR_DIE);
739 #endif /* defined(CONFIG_BOOKE) || defined(CONFIG_40x) */
742 void __init generic_calibrate_decr(void)
744 ppc_tb_freq = DEFAULT_TB_FREQ; /* hardcoded default */
746 if (!get_freq("ibm,extended-timebase-frequency", 2, &ppc_tb_freq) &&
747 !get_freq("timebase-frequency", 1, &ppc_tb_freq)) {
749 printk(KERN_ERR "WARNING: Estimating decrementer frequency "
753 ppc_proc_freq = DEFAULT_PROC_FREQ; /* hardcoded default */
755 if (!get_freq("ibm,extended-clock-frequency", 2, &ppc_proc_freq) &&
756 !get_freq("clock-frequency", 1, &ppc_proc_freq)) {
758 printk(KERN_ERR "WARNING: Estimating processor frequency "
763 int update_persistent_clock(struct timespec now)
767 if (!ppc_md.set_rtc_time)
770 to_tm(now.tv_sec + 1 + timezone_offset, &tm);
774 return ppc_md.set_rtc_time(&tm);
777 void read_persistent_clock(struct timespec *ts)
780 static int first = 1;
783 /* XXX this is a litle fragile but will work okay in the short term */
786 if (ppc_md.time_init)
787 timezone_offset = ppc_md.time_init();
789 /* get_boot_time() isn't guaranteed to be safe to call late */
790 if (ppc_md.get_boot_time) {
791 ts->tv_sec = ppc_md.get_boot_time() - timezone_offset;
795 if (!ppc_md.get_rtc_time) {
799 ppc_md.get_rtc_time(&tm);
800 ts->tv_sec = mktime(tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday,
801 tm.tm_hour, tm.tm_min, tm.tm_sec);
804 /* clocksource code */
805 static cycle_t rtc_read(struct clocksource *cs)
807 return (cycle_t)get_rtc();
810 static cycle_t timebase_read(struct clocksource *cs)
812 return (cycle_t)get_tb();
815 void update_vsyscall(struct timespec *wall_time, struct clocksource *clock)
819 if (clock != &clocksource_timebase)
822 /* Make userspace gettimeofday spin until we're done. */
823 ++vdso_data->tb_update_count;
826 /* XXX this assumes clock->shift == 22 */
827 /* 4611686018 ~= 2^(20+64-22) / 1e9 */
828 t2x = (u64) clock->mult * 4611686018ULL;
829 stamp_xsec = (u64) xtime.tv_nsec * XSEC_PER_SEC;
830 do_div(stamp_xsec, 1000000000);
831 stamp_xsec += (u64) xtime.tv_sec * XSEC_PER_SEC;
832 update_gtod(clock->cycle_last, stamp_xsec, t2x);
835 void update_vsyscall_tz(void)
837 /* Make userspace gettimeofday spin until we're done. */
838 ++vdso_data->tb_update_count;
840 vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
841 vdso_data->tz_dsttime = sys_tz.tz_dsttime;
843 ++vdso_data->tb_update_count;
846 static void __init clocksource_init(void)
848 struct clocksource *clock;
851 clock = &clocksource_rtc;
853 clock = &clocksource_timebase;
855 clock->mult = clocksource_hz2mult(tb_ticks_per_sec, clock->shift);
857 if (clocksource_register(clock)) {
858 printk(KERN_ERR "clocksource: %s is already registered\n",
863 printk(KERN_INFO "clocksource: %s mult[%x] shift[%d] registered\n",
864 clock->name, clock->mult, clock->shift);
867 static int decrementer_set_next_event(unsigned long evt,
868 struct clock_event_device *dev)
870 __get_cpu_var(decrementers).next_tb = get_tb_or_rtc() + evt;
875 static void decrementer_set_mode(enum clock_event_mode mode,
876 struct clock_event_device *dev)
878 if (mode != CLOCK_EVT_MODE_ONESHOT)
879 decrementer_set_next_event(DECREMENTER_MAX, dev);
882 static void __init setup_clockevent_multiplier(unsigned long hz)
884 u64 mult, shift = 32;
887 mult = div_sc(hz, NSEC_PER_SEC, shift);
888 if (mult && (mult >> 32UL) == 0UL)
894 decrementer_clockevent.shift = shift;
895 decrementer_clockevent.mult = mult;
898 static void register_decrementer_clockevent(int cpu)
900 struct clock_event_device *dec = &per_cpu(decrementers, cpu).event;
902 *dec = decrementer_clockevent;
903 dec->cpumask = cpumask_of(cpu);
905 printk(KERN_DEBUG "clockevent: %s mult[%lx] shift[%d] cpu[%d]\n",
906 dec->name, dec->mult, dec->shift, cpu);
908 clockevents_register_device(dec);
911 static void __init init_decrementer_clockevent(void)
913 int cpu = smp_processor_id();
915 setup_clockevent_multiplier(ppc_tb_freq);
916 decrementer_clockevent.max_delta_ns =
917 clockevent_delta2ns(DECREMENTER_MAX, &decrementer_clockevent);
918 decrementer_clockevent.min_delta_ns =
919 clockevent_delta2ns(2, &decrementer_clockevent);
921 register_decrementer_clockevent(cpu);
924 void secondary_cpu_time_init(void)
926 /* Start the decrementer on CPUs that have manual control
929 start_cpu_decrementer();
931 /* FIME: Should make unrelatred change to move snapshot_timebase
933 register_decrementer_clockevent(smp_processor_id());
936 /* This function is only called on the boot processor */
937 void __init time_init(void)
940 struct div_result res;
945 /* 601 processor: dec counts down by 128 every 128ns */
946 ppc_tb_freq = 1000000000;
947 tb_last_jiffy = get_rtcl();
949 /* Normal PowerPC with timebase register */
950 ppc_md.calibrate_decr();
951 printk(KERN_DEBUG "time_init: decrementer frequency = %lu.%.6lu MHz\n",
952 ppc_tb_freq / 1000000, ppc_tb_freq % 1000000);
953 printk(KERN_DEBUG "time_init: processor frequency = %lu.%.6lu MHz\n",
954 ppc_proc_freq / 1000000, ppc_proc_freq % 1000000);
955 tb_last_jiffy = get_tb();
958 tb_ticks_per_jiffy = ppc_tb_freq / HZ;
959 tb_ticks_per_sec = ppc_tb_freq;
960 tb_ticks_per_usec = ppc_tb_freq / 1000000;
961 tb_to_us = mulhwu_scale_factor(ppc_tb_freq, 1000000);
962 calc_cputime_factors();
965 * Calculate the length of each tick in ns. It will not be
966 * exactly 1e9/HZ unless ppc_tb_freq is divisible by HZ.
967 * We compute 1e9 * tb_ticks_per_jiffy / ppc_tb_freq,
970 x = (u64) NSEC_PER_SEC * tb_ticks_per_jiffy + ppc_tb_freq - 1;
971 do_div(x, ppc_tb_freq);
973 last_tick_len = x << TICKLEN_SCALE;
976 * Compute ticklen_to_xs, which is a factor which gets multiplied
977 * by (last_tick_len << TICKLEN_SHIFT) to get a tb_to_xs value.
979 * ticklen_to_xs = 2^N / (tb_ticks_per_jiffy * 1e9)
980 * where N = 64 + 20 - TICKLEN_SCALE - TICKLEN_SHIFT
981 * which turns out to be N = 51 - SHIFT_HZ.
982 * This gives the result as a 0.64 fixed-point fraction.
983 * That value is reduced by an offset amounting to 1 xsec per
984 * 2^31 timebase ticks to avoid problems with time going backwards
985 * by 1 xsec when we do timer_recalc_offset due to losing the
986 * fractional xsec. That offset is equal to ppc_tb_freq/2^51
987 * since there are 2^20 xsec in a second.
989 div128_by_32((1ULL << 51) - ppc_tb_freq, 0,
990 tb_ticks_per_jiffy << SHIFT_HZ, &res);
991 div128_by_32(res.result_high, res.result_low, NSEC_PER_SEC, &res);
992 ticklen_to_xs = res.result_low;
994 /* Compute tb_to_xs from tick_nsec */
995 tb_to_xs = mulhdu(last_tick_len << TICKLEN_SHIFT, ticklen_to_xs);
998 * Compute scale factor for sched_clock.
999 * The calibrate_decr() function has set tb_ticks_per_sec,
1000 * which is the timebase frequency.
1001 * We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
1002 * the 128-bit result as a 64.64 fixed-point number.
1003 * We then shift that number right until it is less than 1.0,
1004 * giving us the scale factor and shift count to use in
1007 div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
1008 scale = res.result_low;
1009 for (shift = 0; res.result_high != 0; ++shift) {
1010 scale = (scale >> 1) | (res.result_high << 63);
1011 res.result_high >>= 1;
1013 tb_to_ns_scale = scale;
1014 tb_to_ns_shift = shift;
1015 /* Save the current timebase to pretty up CONFIG_PRINTK_TIME */
1016 boot_tb = get_tb_or_rtc();
1018 write_seqlock_irqsave(&xtime_lock, flags);
1020 /* If platform provided a timezone (pmac), we correct the time */
1021 if (timezone_offset) {
1022 sys_tz.tz_minuteswest = -timezone_offset / 60;
1023 sys_tz.tz_dsttime = 0;
1026 vdso_data->tb_orig_stamp = tb_last_jiffy;
1027 vdso_data->tb_update_count = 0;
1028 vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
1029 vdso_data->stamp_xsec = (u64) xtime.tv_sec * XSEC_PER_SEC;
1030 vdso_data->tb_to_xs = tb_to_xs;
1032 write_sequnlock_irqrestore(&xtime_lock, flags);
1034 /* Start the decrementer on CPUs that have manual control
1037 start_cpu_decrementer();
1039 /* Register the clocksource, if we're not running on iSeries */
1040 if (!firmware_has_feature(FW_FEATURE_ISERIES))
1043 init_decrementer_clockevent();
1048 #define STARTOFTIME 1970
1049 #define SECDAY 86400L
1050 #define SECYR (SECDAY * 365)
1051 #define leapyear(year) ((year) % 4 == 0 && \
1052 ((year) % 100 != 0 || (year) % 400 == 0))
1053 #define days_in_year(a) (leapyear(a) ? 366 : 365)
1054 #define days_in_month(a) (month_days[(a) - 1])
1056 static int month_days[12] = {
1057 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
1061 * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
1063 void GregorianDay(struct rtc_time * tm)
1068 int MonthOffset[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
1070 lastYear = tm->tm_year - 1;
1073 * Number of leap corrections to apply up to end of last year
1075 leapsToDate = lastYear / 4 - lastYear / 100 + lastYear / 400;
1078 * This year is a leap year if it is divisible by 4 except when it is
1079 * divisible by 100 unless it is divisible by 400
1081 * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 was
1083 day = tm->tm_mon > 2 && leapyear(tm->tm_year);
1085 day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] +
1088 tm->tm_wday = day % 7;
1091 void to_tm(int tim, struct rtc_time * tm)
1094 register long hms, day;
1099 /* Hours, minutes, seconds are easy */
1100 tm->tm_hour = hms / 3600;
1101 tm->tm_min = (hms % 3600) / 60;
1102 tm->tm_sec = (hms % 3600) % 60;
1104 /* Number of years in days */
1105 for (i = STARTOFTIME; day >= days_in_year(i); i++)
1106 day -= days_in_year(i);
1109 /* Number of months in days left */
1110 if (leapyear(tm->tm_year))
1111 days_in_month(FEBRUARY) = 29;
1112 for (i = 1; day >= days_in_month(i); i++)
1113 day -= days_in_month(i);
1114 days_in_month(FEBRUARY) = 28;
1117 /* Days are what is left over (+1) from all that. */
1118 tm->tm_mday = day + 1;
1121 * Determine the day of week
1126 /* Auxiliary function to compute scaling factors */
1127 /* Actually the choice of a timebase running at 1/4 the of the bus
1128 * frequency giving resolution of a few tens of nanoseconds is quite nice.
1129 * It makes this computation very precise (27-28 bits typically) which
1130 * is optimistic considering the stability of most processor clock
1131 * oscillators and the precision with which the timebase frequency
1132 * is measured but does not harm.
1134 unsigned mulhwu_scale_factor(unsigned inscale, unsigned outscale)
1136 unsigned mlt=0, tmp, err;
1137 /* No concern for performance, it's done once: use a stupid
1138 * but safe and compact method to find the multiplier.
1141 for (tmp = 1U<<31; tmp != 0; tmp >>= 1) {
1142 if (mulhwu(inscale, mlt|tmp) < outscale)
1146 /* We might still be off by 1 for the best approximation.
1147 * A side effect of this is that if outscale is too large
1148 * the returned value will be zero.
1149 * Many corner cases have been checked and seem to work,
1150 * some might have been forgotten in the test however.
1153 err = inscale * (mlt+1);
1154 if (err <= inscale/2)
1160 * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
1163 void div128_by_32(u64 dividend_high, u64 dividend_low,
1164 unsigned divisor, struct div_result *dr)
1166 unsigned long a, b, c, d;
1167 unsigned long w, x, y, z;
1170 a = dividend_high >> 32;
1171 b = dividend_high & 0xffffffff;
1172 c = dividend_low >> 32;
1173 d = dividend_low & 0xffffffff;
1176 ra = ((u64)(a - (w * divisor)) << 32) + b;
1178 rb = ((u64) do_div(ra, divisor) << 32) + c;
1181 rc = ((u64) do_div(rb, divisor) << 32) + d;
1184 do_div(rc, divisor);
1187 dr->result_high = ((u64)w << 32) + x;
1188 dr->result_low = ((u64)y << 32) + z;
1192 /* We don't need to calibrate delay, we use the CPU timebase for that */
1193 void calibrate_delay(void)
1195 /* Some generic code (such as spinlock debug) use loops_per_jiffy
1196 * as the number of __delay(1) in a jiffy, so make it so
1198 loops_per_jiffy = tb_ticks_per_jiffy;
1201 static int __init rtc_init(void)
1203 struct platform_device *pdev;
1205 if (!ppc_md.get_rtc_time)
1208 pdev = platform_device_register_simple("rtc-generic", -1, NULL, 0);
1210 return PTR_ERR(pdev);
1215 module_init(rtc_init);