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 #include <asm/cputime.h>
70 #ifdef CONFIG_PPC_ISERIES
71 #include <asm/iseries/it_lp_queue.h>
72 #include <asm/iseries/hv_call_xm.h>
75 /* powerpc clocksource/clockevent code */
77 #include <linux/clockchips.h>
78 #include <linux/clocksource.h>
80 static cycle_t rtc_read(void);
81 static struct clocksource clocksource_rtc = {
84 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
85 .mask = CLOCKSOURCE_MASK(64),
87 .mult = 0, /* To be filled in */
91 static cycle_t timebase_read(void);
92 static struct clocksource clocksource_timebase = {
95 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
96 .mask = CLOCKSOURCE_MASK(64),
98 .mult = 0, /* To be filled in */
99 .read = timebase_read,
102 #define DECREMENTER_MAX 0x7fffffff
104 static int decrementer_set_next_event(unsigned long evt,
105 struct clock_event_device *dev);
106 static void decrementer_set_mode(enum clock_event_mode mode,
107 struct clock_event_device *dev);
109 static struct clock_event_device decrementer_clockevent = {
110 .name = "decrementer",
113 .mult = 0, /* To be filled in */
115 .set_next_event = decrementer_set_next_event,
116 .set_mode = decrementer_set_mode,
117 .features = CLOCK_EVT_FEAT_ONESHOT,
120 struct decrementer_clock {
121 struct clock_event_device event;
125 static DEFINE_PER_CPU(struct decrementer_clock, decrementers);
127 #ifdef CONFIG_PPC_ISERIES
128 static unsigned long __initdata iSeries_recal_titan;
129 static signed long __initdata iSeries_recal_tb;
131 /* Forward declaration is only needed for iSereis compiles */
132 static void __init clocksource_init(void);
135 #define XSEC_PER_SEC (1024*1024)
138 #define SCALE_XSEC(xsec, max) (((xsec) * max) / XSEC_PER_SEC)
140 /* compute ((xsec << 12) * max) >> 32 */
141 #define SCALE_XSEC(xsec, max) mulhwu((xsec) << 12, max)
144 unsigned long tb_ticks_per_jiffy;
145 unsigned long tb_ticks_per_usec = 100; /* sane default */
146 EXPORT_SYMBOL(tb_ticks_per_usec);
147 unsigned long tb_ticks_per_sec;
148 EXPORT_SYMBOL(tb_ticks_per_sec); /* for cputime_t conversions */
152 #define TICKLEN_SCALE NTP_SCALE_SHIFT
153 static u64 last_tick_len; /* units are ns / 2^TICKLEN_SCALE */
154 static u64 ticklen_to_xs; /* 0.64 fraction */
156 /* If last_tick_len corresponds to about 1/HZ seconds, then
157 last_tick_len << TICKLEN_SHIFT will be about 2^63. */
158 #define TICKLEN_SHIFT (63 - 30 - TICKLEN_SCALE + SHIFT_HZ)
160 DEFINE_SPINLOCK(rtc_lock);
161 EXPORT_SYMBOL_GPL(rtc_lock);
163 static u64 tb_to_ns_scale __read_mostly;
164 static unsigned tb_to_ns_shift __read_mostly;
165 static unsigned long boot_tb __read_mostly;
167 extern struct timezone sys_tz;
168 static long timezone_offset;
170 unsigned long ppc_proc_freq;
171 EXPORT_SYMBOL(ppc_proc_freq);
172 unsigned long ppc_tb_freq;
174 static u64 tb_last_jiffy __cacheline_aligned_in_smp;
175 static DEFINE_PER_CPU(u64, last_jiffy);
177 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
179 * Factors for converting from cputime_t (timebase ticks) to
180 * jiffies, milliseconds, seconds, and clock_t (1/USER_HZ seconds).
181 * These are all stored as 0.64 fixed-point binary fractions.
183 u64 __cputime_jiffies_factor;
184 EXPORT_SYMBOL(__cputime_jiffies_factor);
185 u64 __cputime_msec_factor;
186 EXPORT_SYMBOL(__cputime_msec_factor);
187 u64 __cputime_sec_factor;
188 EXPORT_SYMBOL(__cputime_sec_factor);
189 u64 __cputime_clockt_factor;
190 EXPORT_SYMBOL(__cputime_clockt_factor);
191 DEFINE_PER_CPU(unsigned long, cputime_last_delta);
192 DEFINE_PER_CPU(unsigned long, cputime_scaled_last_delta);
194 static void calc_cputime_factors(void)
196 struct div_result res;
198 div128_by_32(HZ, 0, tb_ticks_per_sec, &res);
199 __cputime_jiffies_factor = res.result_low;
200 div128_by_32(1000, 0, tb_ticks_per_sec, &res);
201 __cputime_msec_factor = res.result_low;
202 div128_by_32(1, 0, tb_ticks_per_sec, &res);
203 __cputime_sec_factor = res.result_low;
204 div128_by_32(USER_HZ, 0, tb_ticks_per_sec, &res);
205 __cputime_clockt_factor = res.result_low;
209 * Read the PURR on systems that have it, otherwise the timebase.
211 static u64 read_purr(void)
213 if (cpu_has_feature(CPU_FTR_PURR))
214 return mfspr(SPRN_PURR);
219 * Read the SPURR on systems that have it, otherwise the purr
221 static u64 read_spurr(u64 purr)
224 * cpus without PURR won't have a SPURR
225 * We already know the former when we use this, so tell gcc
227 if (cpu_has_feature(CPU_FTR_PURR) && cpu_has_feature(CPU_FTR_SPURR))
228 return mfspr(SPRN_SPURR);
233 * Account time for a transition between system, hard irq
236 void account_system_vtime(struct task_struct *tsk)
238 u64 now, nowscaled, delta, deltascaled, sys_time;
241 local_irq_save(flags);
243 nowscaled = read_spurr(now);
244 delta = now - get_paca()->startpurr;
245 deltascaled = nowscaled - get_paca()->startspurr;
246 get_paca()->startpurr = now;
247 get_paca()->startspurr = nowscaled;
248 if (!in_interrupt()) {
249 /* deltascaled includes both user and system time.
250 * Hence scale it based on the purr ratio to estimate
252 sys_time = get_paca()->system_time;
253 if (get_paca()->user_time)
254 deltascaled = deltascaled * sys_time /
255 (sys_time + get_paca()->user_time);
257 get_paca()->system_time = 0;
259 account_system_time(tsk, 0, delta, deltascaled);
260 per_cpu(cputime_last_delta, smp_processor_id()) = delta;
261 per_cpu(cputime_scaled_last_delta, smp_processor_id()) = deltascaled;
262 local_irq_restore(flags);
266 * Transfer the user and system times accumulated in the paca
267 * by the exception entry and exit code to the generic process
268 * user and system time records.
269 * Must be called with interrupts disabled.
271 void account_process_tick(struct task_struct *tsk, int user_tick)
273 cputime_t utime, utimescaled;
275 utime = get_paca()->user_time;
276 get_paca()->user_time = 0;
277 utimescaled = cputime_to_scaled(utime);
278 account_user_time(tsk, utime, utimescaled);
282 * Stuff for accounting stolen time.
284 struct cpu_purr_data {
285 int initialized; /* thread is running */
286 u64 tb; /* last TB value read */
287 u64 purr; /* last PURR value read */
288 u64 spurr; /* last SPURR value read */
292 * Each entry in the cpu_purr_data array is manipulated only by its
293 * "owner" cpu -- usually in the timer interrupt but also occasionally
294 * in process context for cpu online. As long as cpus do not touch
295 * each others' cpu_purr_data, disabling local interrupts is
296 * sufficient to serialize accesses.
298 static DEFINE_PER_CPU(struct cpu_purr_data, cpu_purr_data);
300 static void snapshot_tb_and_purr(void *data)
303 struct cpu_purr_data *p = &__get_cpu_var(cpu_purr_data);
305 local_irq_save(flags);
306 p->tb = get_tb_or_rtc();
307 p->purr = mfspr(SPRN_PURR);
310 local_irq_restore(flags);
314 * Called during boot when all cpus have come up.
316 void snapshot_timebases(void)
318 if (!cpu_has_feature(CPU_FTR_PURR))
320 on_each_cpu(snapshot_tb_and_purr, NULL, 1);
324 * Must be called with interrupts disabled.
326 void calculate_steal_time(void)
330 struct cpu_purr_data *pme;
332 pme = &__get_cpu_var(cpu_purr_data);
333 if (!pme->initialized)
334 return; /* !CPU_FTR_PURR or early in early boot */
336 purr = mfspr(SPRN_PURR);
337 stolen = (tb - pme->tb) - (purr - pme->purr);
339 account_steal_time(current, stolen);
344 #ifdef CONFIG_PPC_SPLPAR
346 * Must be called before the cpu is added to the online map when
347 * a cpu is being brought up at runtime.
349 static void snapshot_purr(void)
351 struct cpu_purr_data *pme;
354 if (!cpu_has_feature(CPU_FTR_PURR))
356 local_irq_save(flags);
357 pme = &__get_cpu_var(cpu_purr_data);
359 pme->purr = mfspr(SPRN_PURR);
360 pme->initialized = 1;
361 local_irq_restore(flags);
364 #endif /* CONFIG_PPC_SPLPAR */
366 #else /* ! CONFIG_VIRT_CPU_ACCOUNTING */
367 #define calc_cputime_factors()
368 #define calculate_steal_time() do { } while (0)
371 #if !(defined(CONFIG_VIRT_CPU_ACCOUNTING) && defined(CONFIG_PPC_SPLPAR))
372 #define snapshot_purr() do { } while (0)
376 * Called when a cpu comes up after the system has finished booting,
377 * i.e. as a result of a hotplug cpu action.
379 void snapshot_timebase(void)
381 __get_cpu_var(last_jiffy) = get_tb_or_rtc();
385 void __delay(unsigned long loops)
393 /* the RTCL register wraps at 1000000000 */
394 diff = get_rtcl() - start;
397 } while (diff < loops);
400 while (get_tbl() - start < loops)
405 EXPORT_SYMBOL(__delay);
407 void udelay(unsigned long usecs)
409 __delay(tb_ticks_per_usec * usecs);
411 EXPORT_SYMBOL(udelay);
413 static inline void update_gtod(u64 new_tb_stamp, u64 new_stamp_xsec,
417 * tb_update_count is used to allow the userspace gettimeofday code
418 * to assure itself that it sees a consistent view of the tb_to_xs and
419 * stamp_xsec variables. It reads the tb_update_count, then reads
420 * tb_to_xs and stamp_xsec and then reads tb_update_count again. If
421 * the two values of tb_update_count match and are even then the
422 * tb_to_xs and stamp_xsec values are consistent. If not, then it
423 * loops back and reads them again until this criteria is met.
424 * We expect the caller to have done the first increment of
425 * vdso_data->tb_update_count already.
427 vdso_data->tb_orig_stamp = new_tb_stamp;
428 vdso_data->stamp_xsec = new_stamp_xsec;
429 vdso_data->tb_to_xs = new_tb_to_xs;
430 vdso_data->wtom_clock_sec = wall_to_monotonic.tv_sec;
431 vdso_data->wtom_clock_nsec = wall_to_monotonic.tv_nsec;
432 vdso_data->stamp_xtime = xtime;
434 ++(vdso_data->tb_update_count);
438 unsigned long profile_pc(struct pt_regs *regs)
440 unsigned long pc = instruction_pointer(regs);
442 if (in_lock_functions(pc))
447 EXPORT_SYMBOL(profile_pc);
450 #ifdef CONFIG_PPC_ISERIES
453 * This function recalibrates the timebase based on the 49-bit time-of-day
454 * value in the Titan chip. The Titan is much more accurate than the value
455 * returned by the service processor for the timebase frequency.
458 static int __init iSeries_tb_recal(void)
460 struct div_result divres;
461 unsigned long titan, tb;
463 /* Make sure we only run on iSeries */
464 if (!firmware_has_feature(FW_FEATURE_ISERIES))
468 titan = HvCallXm_loadTod();
469 if ( iSeries_recal_titan ) {
470 unsigned long tb_ticks = tb - iSeries_recal_tb;
471 unsigned long titan_usec = (titan - iSeries_recal_titan) >> 12;
472 unsigned long new_tb_ticks_per_sec = (tb_ticks * USEC_PER_SEC)/titan_usec;
473 unsigned long new_tb_ticks_per_jiffy = (new_tb_ticks_per_sec+(HZ/2))/HZ;
474 long tick_diff = new_tb_ticks_per_jiffy - tb_ticks_per_jiffy;
476 /* make sure tb_ticks_per_sec and tb_ticks_per_jiffy are consistent */
477 new_tb_ticks_per_sec = new_tb_ticks_per_jiffy * HZ;
479 if ( tick_diff < 0 ) {
480 tick_diff = -tick_diff;
484 if ( tick_diff < tb_ticks_per_jiffy/25 ) {
485 printk( "Titan recalibrate: new tb_ticks_per_jiffy = %lu (%c%ld)\n",
486 new_tb_ticks_per_jiffy, sign, tick_diff );
487 tb_ticks_per_jiffy = new_tb_ticks_per_jiffy;
488 tb_ticks_per_sec = new_tb_ticks_per_sec;
489 calc_cputime_factors();
490 div128_by_32( XSEC_PER_SEC, 0, tb_ticks_per_sec, &divres );
491 tb_to_xs = divres.result_low;
492 vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
493 vdso_data->tb_to_xs = tb_to_xs;
496 printk( "Titan recalibrate: FAILED (difference > 4 percent)\n"
497 " new tb_ticks_per_jiffy = %lu\n"
498 " old tb_ticks_per_jiffy = %lu\n",
499 new_tb_ticks_per_jiffy, tb_ticks_per_jiffy );
503 iSeries_recal_titan = titan;
504 iSeries_recal_tb = tb;
506 /* Called here as now we know accurate values for the timebase */
510 late_initcall(iSeries_tb_recal);
512 /* Called from platform early init */
513 void __init iSeries_time_init_early(void)
515 iSeries_recal_tb = get_tb();
516 iSeries_recal_titan = HvCallXm_loadTod();
518 #endif /* CONFIG_PPC_ISERIES */
521 * For iSeries shared processors, we have to let the hypervisor
522 * set the hardware decrementer. We set a virtual decrementer
523 * in the lppaca and call the hypervisor if the virtual
524 * decrementer is less than the current value in the hardware
525 * decrementer. (almost always the new decrementer value will
526 * be greater than the current hardware decementer so the hypervisor
527 * call will not be needed)
531 * timer_interrupt - gets called when the decrementer overflows,
532 * with interrupts disabled.
534 void timer_interrupt(struct pt_regs * regs)
536 struct pt_regs *old_regs;
537 struct decrementer_clock *decrementer = &__get_cpu_var(decrementers);
538 struct clock_event_device *evt = &decrementer->event;
541 /* Ensure a positive value is written to the decrementer, or else
542 * some CPUs will continuue to take decrementer exceptions */
543 set_dec(DECREMENTER_MAX);
546 if (atomic_read(&ppc_n_lost_interrupts) != 0)
550 now = get_tb_or_rtc();
551 if (now < decrementer->next_tb) {
552 /* not time for this event yet */
553 now = decrementer->next_tb - now;
554 if (now <= DECREMENTER_MAX)
558 old_regs = set_irq_regs(regs);
561 calculate_steal_time();
563 #ifdef CONFIG_PPC_ISERIES
564 if (firmware_has_feature(FW_FEATURE_ISERIES))
565 get_lppaca()->int_dword.fields.decr_int = 0;
568 if (evt->event_handler)
569 evt->event_handler(evt);
571 #ifdef CONFIG_PPC_ISERIES
572 if (firmware_has_feature(FW_FEATURE_ISERIES) && hvlpevent_is_pending())
573 process_hvlpevents();
577 /* collect purr register values often, for accurate calculations */
578 if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
579 struct cpu_usage *cu = &__get_cpu_var(cpu_usage_array);
580 cu->current_tb = mfspr(SPRN_PURR);
585 set_irq_regs(old_regs);
588 void wakeup_decrementer(void)
593 * The timebase gets saved on sleep and restored on wakeup,
594 * so all we need to do is to reset the decrementer.
596 ticks = tb_ticks_since(__get_cpu_var(last_jiffy));
597 if (ticks < tb_ticks_per_jiffy)
598 ticks = tb_ticks_per_jiffy - ticks;
604 #ifdef CONFIG_SUSPEND
605 void generic_suspend_disable_irqs(void)
609 /* Disable the decrementer, so that it doesn't interfere
618 void generic_suspend_enable_irqs(void)
620 wakeup_decrementer();
626 /* Overrides the weak version in kernel/power/main.c */
627 void arch_suspend_disable_irqs(void)
629 if (ppc_md.suspend_disable_irqs)
630 ppc_md.suspend_disable_irqs();
631 generic_suspend_disable_irqs();
634 /* Overrides the weak version in kernel/power/main.c */
635 void arch_suspend_enable_irqs(void)
637 generic_suspend_enable_irqs();
638 if (ppc_md.suspend_enable_irqs)
639 ppc_md.suspend_enable_irqs();
644 void __init smp_space_timers(unsigned int max_cpus)
647 u64 previous_tb = per_cpu(last_jiffy, boot_cpuid);
649 /* make sure tb > per_cpu(last_jiffy, cpu) for all cpus always */
650 previous_tb -= tb_ticks_per_jiffy;
652 for_each_possible_cpu(i) {
655 per_cpu(last_jiffy, i) = previous_tb;
661 * Scheduler clock - returns current time in nanosec units.
663 * Note: mulhdu(a, b) (multiply high double unsigned) returns
664 * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
665 * are 64-bit unsigned numbers.
667 unsigned long long sched_clock(void)
671 return mulhdu(get_tb() - boot_tb, tb_to_ns_scale) << tb_to_ns_shift;
674 static int __init get_freq(char *name, int cells, unsigned long *val)
676 struct device_node *cpu;
677 const unsigned int *fp;
680 /* The cpu node should have timebase and clock frequency properties */
681 cpu = of_find_node_by_type(NULL, "cpu");
684 fp = of_get_property(cpu, name, NULL);
687 *val = of_read_ulong(fp, cells);
696 void __init generic_calibrate_decr(void)
698 ppc_tb_freq = DEFAULT_TB_FREQ; /* hardcoded default */
700 if (!get_freq("ibm,extended-timebase-frequency", 2, &ppc_tb_freq) &&
701 !get_freq("timebase-frequency", 1, &ppc_tb_freq)) {
703 printk(KERN_ERR "WARNING: Estimating decrementer frequency "
707 ppc_proc_freq = DEFAULT_PROC_FREQ; /* hardcoded default */
709 if (!get_freq("ibm,extended-clock-frequency", 2, &ppc_proc_freq) &&
710 !get_freq("clock-frequency", 1, &ppc_proc_freq)) {
712 printk(KERN_ERR "WARNING: Estimating processor frequency "
716 #if defined(CONFIG_BOOKE) || defined(CONFIG_40x)
717 /* Clear any pending timer interrupts */
718 mtspr(SPRN_TSR, TSR_ENW | TSR_WIS | TSR_DIS | TSR_FIS);
720 /* Enable decrementer interrupt */
721 mtspr(SPRN_TCR, TCR_DIE);
725 int update_persistent_clock(struct timespec now)
729 if (!ppc_md.set_rtc_time)
732 to_tm(now.tv_sec + 1 + timezone_offset, &tm);
736 return ppc_md.set_rtc_time(&tm);
739 unsigned long read_persistent_clock(void)
742 static int first = 1;
744 /* XXX this is a litle fragile but will work okay in the short term */
747 if (ppc_md.time_init)
748 timezone_offset = ppc_md.time_init();
750 /* get_boot_time() isn't guaranteed to be safe to call late */
751 if (ppc_md.get_boot_time)
752 return ppc_md.get_boot_time() -timezone_offset;
754 if (!ppc_md.get_rtc_time)
756 ppc_md.get_rtc_time(&tm);
757 return mktime(tm.tm_year+1900, tm.tm_mon+1, tm.tm_mday,
758 tm.tm_hour, tm.tm_min, tm.tm_sec);
761 /* clocksource code */
762 static cycle_t rtc_read(void)
764 return (cycle_t)get_rtc();
767 static cycle_t timebase_read(void)
769 return (cycle_t)get_tb();
772 void update_vsyscall(struct timespec *wall_time, struct clocksource *clock)
776 if (clock != &clocksource_timebase)
779 /* Make userspace gettimeofday spin until we're done. */
780 ++vdso_data->tb_update_count;
783 /* XXX this assumes clock->shift == 22 */
784 /* 4611686018 ~= 2^(20+64-22) / 1e9 */
785 t2x = (u64) clock->mult * 4611686018ULL;
786 stamp_xsec = (u64) xtime.tv_nsec * XSEC_PER_SEC;
787 do_div(stamp_xsec, 1000000000);
788 stamp_xsec += (u64) xtime.tv_sec * XSEC_PER_SEC;
789 update_gtod(clock->cycle_last, stamp_xsec, t2x);
792 void update_vsyscall_tz(void)
794 /* Make userspace gettimeofday spin until we're done. */
795 ++vdso_data->tb_update_count;
797 vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
798 vdso_data->tz_dsttime = sys_tz.tz_dsttime;
800 ++vdso_data->tb_update_count;
803 static void __init clocksource_init(void)
805 struct clocksource *clock;
808 clock = &clocksource_rtc;
810 clock = &clocksource_timebase;
812 clock->mult = clocksource_hz2mult(tb_ticks_per_sec, clock->shift);
814 if (clocksource_register(clock)) {
815 printk(KERN_ERR "clocksource: %s is already registered\n",
820 printk(KERN_INFO "clocksource: %s mult[%x] shift[%d] registered\n",
821 clock->name, clock->mult, clock->shift);
824 static int decrementer_set_next_event(unsigned long evt,
825 struct clock_event_device *dev)
827 __get_cpu_var(decrementers).next_tb = get_tb_or_rtc() + evt;
832 static void decrementer_set_mode(enum clock_event_mode mode,
833 struct clock_event_device *dev)
835 if (mode != CLOCK_EVT_MODE_ONESHOT)
836 decrementer_set_next_event(DECREMENTER_MAX, dev);
839 static void register_decrementer_clockevent(int cpu)
841 struct clock_event_device *dec = &per_cpu(decrementers, cpu).event;
843 *dec = decrementer_clockevent;
844 dec->cpumask = cpumask_of_cpu(cpu);
846 printk(KERN_DEBUG "clockevent: %s mult[%lx] shift[%d] cpu[%d]\n",
847 dec->name, dec->mult, dec->shift, cpu);
849 clockevents_register_device(dec);
852 static void __init init_decrementer_clockevent(void)
854 int cpu = smp_processor_id();
856 decrementer_clockevent.mult = div_sc(ppc_tb_freq, NSEC_PER_SEC,
857 decrementer_clockevent.shift);
858 decrementer_clockevent.max_delta_ns =
859 clockevent_delta2ns(DECREMENTER_MAX, &decrementer_clockevent);
860 decrementer_clockevent.min_delta_ns =
861 clockevent_delta2ns(2, &decrementer_clockevent);
863 register_decrementer_clockevent(cpu);
866 void secondary_cpu_time_init(void)
868 /* FIME: Should make unrelatred change to move snapshot_timebase
870 register_decrementer_clockevent(smp_processor_id());
873 /* This function is only called on the boot processor */
874 void __init time_init(void)
877 struct div_result res;
882 /* 601 processor: dec counts down by 128 every 128ns */
883 ppc_tb_freq = 1000000000;
884 tb_last_jiffy = get_rtcl();
886 /* Normal PowerPC with timebase register */
887 ppc_md.calibrate_decr();
888 printk(KERN_DEBUG "time_init: decrementer frequency = %lu.%.6lu MHz\n",
889 ppc_tb_freq / 1000000, ppc_tb_freq % 1000000);
890 printk(KERN_DEBUG "time_init: processor frequency = %lu.%.6lu MHz\n",
891 ppc_proc_freq / 1000000, ppc_proc_freq % 1000000);
892 tb_last_jiffy = get_tb();
895 tb_ticks_per_jiffy = ppc_tb_freq / HZ;
896 tb_ticks_per_sec = ppc_tb_freq;
897 tb_ticks_per_usec = ppc_tb_freq / 1000000;
898 tb_to_us = mulhwu_scale_factor(ppc_tb_freq, 1000000);
899 calc_cputime_factors();
902 * Calculate the length of each tick in ns. It will not be
903 * exactly 1e9/HZ unless ppc_tb_freq is divisible by HZ.
904 * We compute 1e9 * tb_ticks_per_jiffy / ppc_tb_freq,
907 x = (u64) NSEC_PER_SEC * tb_ticks_per_jiffy + ppc_tb_freq - 1;
908 do_div(x, ppc_tb_freq);
910 last_tick_len = x << TICKLEN_SCALE;
913 * Compute ticklen_to_xs, which is a factor which gets multiplied
914 * by (last_tick_len << TICKLEN_SHIFT) to get a tb_to_xs value.
916 * ticklen_to_xs = 2^N / (tb_ticks_per_jiffy * 1e9)
917 * where N = 64 + 20 - TICKLEN_SCALE - TICKLEN_SHIFT
918 * which turns out to be N = 51 - SHIFT_HZ.
919 * This gives the result as a 0.64 fixed-point fraction.
920 * That value is reduced by an offset amounting to 1 xsec per
921 * 2^31 timebase ticks to avoid problems with time going backwards
922 * by 1 xsec when we do timer_recalc_offset due to losing the
923 * fractional xsec. That offset is equal to ppc_tb_freq/2^51
924 * since there are 2^20 xsec in a second.
926 div128_by_32((1ULL << 51) - ppc_tb_freq, 0,
927 tb_ticks_per_jiffy << SHIFT_HZ, &res);
928 div128_by_32(res.result_high, res.result_low, NSEC_PER_SEC, &res);
929 ticklen_to_xs = res.result_low;
931 /* Compute tb_to_xs from tick_nsec */
932 tb_to_xs = mulhdu(last_tick_len << TICKLEN_SHIFT, ticklen_to_xs);
935 * Compute scale factor for sched_clock.
936 * The calibrate_decr() function has set tb_ticks_per_sec,
937 * which is the timebase frequency.
938 * We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
939 * the 128-bit result as a 64.64 fixed-point number.
940 * We then shift that number right until it is less than 1.0,
941 * giving us the scale factor and shift count to use in
944 div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
945 scale = res.result_low;
946 for (shift = 0; res.result_high != 0; ++shift) {
947 scale = (scale >> 1) | (res.result_high << 63);
948 res.result_high >>= 1;
950 tb_to_ns_scale = scale;
951 tb_to_ns_shift = shift;
952 /* Save the current timebase to pretty up CONFIG_PRINTK_TIME */
953 boot_tb = get_tb_or_rtc();
955 write_seqlock_irqsave(&xtime_lock, flags);
957 /* If platform provided a timezone (pmac), we correct the time */
958 if (timezone_offset) {
959 sys_tz.tz_minuteswest = -timezone_offset / 60;
960 sys_tz.tz_dsttime = 0;
963 vdso_data->tb_orig_stamp = tb_last_jiffy;
964 vdso_data->tb_update_count = 0;
965 vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
966 vdso_data->stamp_xsec = (u64) xtime.tv_sec * XSEC_PER_SEC;
967 vdso_data->tb_to_xs = tb_to_xs;
969 write_sequnlock_irqrestore(&xtime_lock, flags);
971 /* Register the clocksource, if we're not running on iSeries */
972 if (!firmware_has_feature(FW_FEATURE_ISERIES))
975 init_decrementer_clockevent();
980 #define STARTOFTIME 1970
981 #define SECDAY 86400L
982 #define SECYR (SECDAY * 365)
983 #define leapyear(year) ((year) % 4 == 0 && \
984 ((year) % 100 != 0 || (year) % 400 == 0))
985 #define days_in_year(a) (leapyear(a) ? 366 : 365)
986 #define days_in_month(a) (month_days[(a) - 1])
988 static int month_days[12] = {
989 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
993 * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
995 void GregorianDay(struct rtc_time * tm)
1000 int MonthOffset[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
1002 lastYear = tm->tm_year - 1;
1005 * Number of leap corrections to apply up to end of last year
1007 leapsToDate = lastYear / 4 - lastYear / 100 + lastYear / 400;
1010 * This year is a leap year if it is divisible by 4 except when it is
1011 * divisible by 100 unless it is divisible by 400
1013 * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 was
1015 day = tm->tm_mon > 2 && leapyear(tm->tm_year);
1017 day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] +
1020 tm->tm_wday = day % 7;
1023 void to_tm(int tim, struct rtc_time * tm)
1026 register long hms, day;
1031 /* Hours, minutes, seconds are easy */
1032 tm->tm_hour = hms / 3600;
1033 tm->tm_min = (hms % 3600) / 60;
1034 tm->tm_sec = (hms % 3600) % 60;
1036 /* Number of years in days */
1037 for (i = STARTOFTIME; day >= days_in_year(i); i++)
1038 day -= days_in_year(i);
1041 /* Number of months in days left */
1042 if (leapyear(tm->tm_year))
1043 days_in_month(FEBRUARY) = 29;
1044 for (i = 1; day >= days_in_month(i); i++)
1045 day -= days_in_month(i);
1046 days_in_month(FEBRUARY) = 28;
1049 /* Days are what is left over (+1) from all that. */
1050 tm->tm_mday = day + 1;
1053 * Determine the day of week
1058 /* Auxiliary function to compute scaling factors */
1059 /* Actually the choice of a timebase running at 1/4 the of the bus
1060 * frequency giving resolution of a few tens of nanoseconds is quite nice.
1061 * It makes this computation very precise (27-28 bits typically) which
1062 * is optimistic considering the stability of most processor clock
1063 * oscillators and the precision with which the timebase frequency
1064 * is measured but does not harm.
1066 unsigned mulhwu_scale_factor(unsigned inscale, unsigned outscale)
1068 unsigned mlt=0, tmp, err;
1069 /* No concern for performance, it's done once: use a stupid
1070 * but safe and compact method to find the multiplier.
1073 for (tmp = 1U<<31; tmp != 0; tmp >>= 1) {
1074 if (mulhwu(inscale, mlt|tmp) < outscale)
1078 /* We might still be off by 1 for the best approximation.
1079 * A side effect of this is that if outscale is too large
1080 * the returned value will be zero.
1081 * Many corner cases have been checked and seem to work,
1082 * some might have been forgotten in the test however.
1085 err = inscale * (mlt+1);
1086 if (err <= inscale/2)
1092 * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
1095 void div128_by_32(u64 dividend_high, u64 dividend_low,
1096 unsigned divisor, struct div_result *dr)
1098 unsigned long a, b, c, d;
1099 unsigned long w, x, y, z;
1102 a = dividend_high >> 32;
1103 b = dividend_high & 0xffffffff;
1104 c = dividend_low >> 32;
1105 d = dividend_low & 0xffffffff;
1108 ra = ((u64)(a - (w * divisor)) << 32) + b;
1110 rb = ((u64) do_div(ra, divisor) << 32) + c;
1113 rc = ((u64) do_div(rb, divisor) << 32) + d;
1116 do_div(rc, divisor);
1119 dr->result_high = ((u64)w << 32) + x;
1120 dr->result_low = ((u64)y << 32) + z;