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/clocksource.h>
78 static cycle_t
rtc_read(void);
79 static struct clocksource clocksource_rtc
= {
82 .flags
= CLOCK_SOURCE_IS_CONTINUOUS
,
83 .mask
= CLOCKSOURCE_MASK(64),
85 .mult
= 0, /* To be filled in */
89 static cycle_t
timebase_read(void);
90 static struct clocksource clocksource_timebase
= {
93 .flags
= CLOCK_SOURCE_IS_CONTINUOUS
,
94 .mask
= CLOCKSOURCE_MASK(64),
96 .mult
= 0, /* To be filled in */
97 .read
= timebase_read
,
100 #ifdef CONFIG_PPC_ISERIES
101 static unsigned long __initdata iSeries_recal_titan
;
102 static signed long __initdata iSeries_recal_tb
;
104 /* Forward declaration is only needed for iSereis compiles */
105 void __init
clocksource_init(void);
108 #define XSEC_PER_SEC (1024*1024)
111 #define SCALE_XSEC(xsec, max) (((xsec) * max) / XSEC_PER_SEC)
113 /* compute ((xsec << 12) * max) >> 32 */
114 #define SCALE_XSEC(xsec, max) mulhwu((xsec) << 12, max)
117 unsigned long tb_ticks_per_jiffy
;
118 unsigned long tb_ticks_per_usec
= 100; /* sane default */
119 EXPORT_SYMBOL(tb_ticks_per_usec
);
120 unsigned long tb_ticks_per_sec
;
121 EXPORT_SYMBOL(tb_ticks_per_sec
); /* for cputime_t conversions */
125 #define TICKLEN_SCALE TICK_LENGTH_SHIFT
126 u64 last_tick_len
; /* units are ns / 2^TICKLEN_SCALE */
127 u64 ticklen_to_xs
; /* 0.64 fraction */
129 /* If last_tick_len corresponds to about 1/HZ seconds, then
130 last_tick_len << TICKLEN_SHIFT will be about 2^63. */
131 #define TICKLEN_SHIFT (63 - 30 - TICKLEN_SCALE + SHIFT_HZ)
133 DEFINE_SPINLOCK(rtc_lock
);
134 EXPORT_SYMBOL_GPL(rtc_lock
);
136 static u64 tb_to_ns_scale __read_mostly
;
137 static unsigned tb_to_ns_shift __read_mostly
;
138 static unsigned long boot_tb __read_mostly
;
140 struct gettimeofday_struct do_gtod
;
142 extern struct timezone sys_tz
;
143 static long timezone_offset
;
145 unsigned long ppc_proc_freq
;
146 EXPORT_SYMBOL(ppc_proc_freq
);
147 unsigned long ppc_tb_freq
;
149 static u64 tb_last_jiffy __cacheline_aligned_in_smp
;
150 static DEFINE_PER_CPU(u64
, last_jiffy
);
152 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
154 * Factors for converting from cputime_t (timebase ticks) to
155 * jiffies, milliseconds, seconds, and clock_t (1/USER_HZ seconds).
156 * These are all stored as 0.64 fixed-point binary fractions.
158 u64 __cputime_jiffies_factor
;
159 EXPORT_SYMBOL(__cputime_jiffies_factor
);
160 u64 __cputime_msec_factor
;
161 EXPORT_SYMBOL(__cputime_msec_factor
);
162 u64 __cputime_sec_factor
;
163 EXPORT_SYMBOL(__cputime_sec_factor
);
164 u64 __cputime_clockt_factor
;
165 EXPORT_SYMBOL(__cputime_clockt_factor
);
167 static void calc_cputime_factors(void)
169 struct div_result res
;
171 div128_by_32(HZ
, 0, tb_ticks_per_sec
, &res
);
172 __cputime_jiffies_factor
= res
.result_low
;
173 div128_by_32(1000, 0, tb_ticks_per_sec
, &res
);
174 __cputime_msec_factor
= res
.result_low
;
175 div128_by_32(1, 0, tb_ticks_per_sec
, &res
);
176 __cputime_sec_factor
= res
.result_low
;
177 div128_by_32(USER_HZ
, 0, tb_ticks_per_sec
, &res
);
178 __cputime_clockt_factor
= res
.result_low
;
182 * Read the PURR on systems that have it, otherwise the timebase.
184 static u64
read_purr(void)
186 if (cpu_has_feature(CPU_FTR_PURR
))
187 return mfspr(SPRN_PURR
);
192 * Account time for a transition between system, hard irq
195 void account_system_vtime(struct task_struct
*tsk
)
200 local_irq_save(flags
);
202 delta
= now
- get_paca()->startpurr
;
203 get_paca()->startpurr
= now
;
204 if (!in_interrupt()) {
205 delta
+= get_paca()->system_time
;
206 get_paca()->system_time
= 0;
208 account_system_time(tsk
, 0, delta
);
209 local_irq_restore(flags
);
213 * Transfer the user and system times accumulated in the paca
214 * by the exception entry and exit code to the generic process
215 * user and system time records.
216 * Must be called with interrupts disabled.
218 void account_process_vtime(struct task_struct
*tsk
)
222 utime
= get_paca()->user_time
;
223 get_paca()->user_time
= 0;
224 account_user_time(tsk
, utime
);
227 static void account_process_time(struct pt_regs
*regs
)
229 int cpu
= smp_processor_id();
231 account_process_vtime(current
);
233 if (rcu_pending(cpu
))
234 rcu_check_callbacks(cpu
, user_mode(regs
));
236 run_posix_cpu_timers(current
);
240 * Stuff for accounting stolen time.
242 struct cpu_purr_data
{
243 int initialized
; /* thread is running */
244 u64 tb
; /* last TB value read */
245 u64 purr
; /* last PURR value read */
249 * Each entry in the cpu_purr_data array is manipulated only by its
250 * "owner" cpu -- usually in the timer interrupt but also occasionally
251 * in process context for cpu online. As long as cpus do not touch
252 * each others' cpu_purr_data, disabling local interrupts is
253 * sufficient to serialize accesses.
255 static DEFINE_PER_CPU(struct cpu_purr_data
, cpu_purr_data
);
257 static void snapshot_tb_and_purr(void *data
)
260 struct cpu_purr_data
*p
= &__get_cpu_var(cpu_purr_data
);
262 local_irq_save(flags
);
263 p
->tb
= get_tb_or_rtc();
264 p
->purr
= mfspr(SPRN_PURR
);
267 local_irq_restore(flags
);
271 * Called during boot when all cpus have come up.
273 void snapshot_timebases(void)
275 if (!cpu_has_feature(CPU_FTR_PURR
))
277 on_each_cpu(snapshot_tb_and_purr
, NULL
, 0, 1);
281 * Must be called with interrupts disabled.
283 void calculate_steal_time(void)
287 struct cpu_purr_data
*pme
;
289 if (!cpu_has_feature(CPU_FTR_PURR
))
291 pme
= &per_cpu(cpu_purr_data
, smp_processor_id());
292 if (!pme
->initialized
)
293 return; /* this can happen in early boot */
295 purr
= mfspr(SPRN_PURR
);
296 stolen
= (tb
- pme
->tb
) - (purr
- pme
->purr
);
298 account_steal_time(current
, stolen
);
303 #ifdef CONFIG_PPC_SPLPAR
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)
310 struct cpu_purr_data
*pme
;
313 if (!cpu_has_feature(CPU_FTR_PURR
))
315 local_irq_save(flags
);
316 pme
= &per_cpu(cpu_purr_data
, smp_processor_id());
318 pme
->purr
= mfspr(SPRN_PURR
);
319 pme
->initialized
= 1;
320 local_irq_restore(flags
);
323 #endif /* CONFIG_PPC_SPLPAR */
325 #else /* ! CONFIG_VIRT_CPU_ACCOUNTING */
326 #define calc_cputime_factors()
327 #define account_process_time(regs) update_process_times(user_mode(regs))
328 #define calculate_steal_time() do { } while (0)
331 #if !(defined(CONFIG_VIRT_CPU_ACCOUNTING) && defined(CONFIG_PPC_SPLPAR))
332 #define snapshot_purr() do { } while (0)
336 * Called when a cpu comes up after the system has finished booting,
337 * i.e. as a result of a hotplug cpu action.
339 void snapshot_timebase(void)
341 __get_cpu_var(last_jiffy
) = get_tb_or_rtc();
345 void __delay(unsigned long loops
)
353 /* the RTCL register wraps at 1000000000 */
354 diff
= get_rtcl() - start
;
357 } while (diff
< loops
);
360 while (get_tbl() - start
< loops
)
365 EXPORT_SYMBOL(__delay
);
367 void udelay(unsigned long usecs
)
369 __delay(tb_ticks_per_usec
* usecs
);
371 EXPORT_SYMBOL(udelay
);
375 * There are two copies of tb_to_xs and stamp_xsec so that no
376 * lock is needed to access and use these values in
377 * do_gettimeofday. We alternate the copies and as long as a
378 * reasonable time elapses between changes, there will never
379 * be inconsistent values. ntpd has a minimum of one minute
382 static inline void update_gtod(u64 new_tb_stamp
, u64 new_stamp_xsec
,
386 struct gettimeofday_vars
*temp_varp
;
388 temp_idx
= (do_gtod
.var_idx
== 0);
389 temp_varp
= &do_gtod
.vars
[temp_idx
];
391 temp_varp
->tb_to_xs
= new_tb_to_xs
;
392 temp_varp
->tb_orig_stamp
= new_tb_stamp
;
393 temp_varp
->stamp_xsec
= new_stamp_xsec
;
395 do_gtod
.varp
= temp_varp
;
396 do_gtod
.var_idx
= temp_idx
;
399 * tb_update_count is used to allow the userspace gettimeofday code
400 * to assure itself that it sees a consistent view of the tb_to_xs and
401 * stamp_xsec variables. It reads the tb_update_count, then reads
402 * tb_to_xs and stamp_xsec and then reads tb_update_count again. If
403 * the two values of tb_update_count match and are even then the
404 * tb_to_xs and stamp_xsec values are consistent. If not, then it
405 * loops back and reads them again until this criteria is met.
406 * We expect the caller to have done the first increment of
407 * vdso_data->tb_update_count already.
409 vdso_data
->tb_orig_stamp
= new_tb_stamp
;
410 vdso_data
->stamp_xsec
= new_stamp_xsec
;
411 vdso_data
->tb_to_xs
= new_tb_to_xs
;
412 vdso_data
->wtom_clock_sec
= wall_to_monotonic
.tv_sec
;
413 vdso_data
->wtom_clock_nsec
= wall_to_monotonic
.tv_nsec
;
415 ++(vdso_data
->tb_update_count
);
419 unsigned long profile_pc(struct pt_regs
*regs
)
421 unsigned long pc
= instruction_pointer(regs
);
423 if (in_lock_functions(pc
))
428 EXPORT_SYMBOL(profile_pc
);
431 #ifdef CONFIG_PPC_ISERIES
434 * This function recalibrates the timebase based on the 49-bit time-of-day
435 * value in the Titan chip. The Titan is much more accurate than the value
436 * returned by the service processor for the timebase frequency.
439 static int __init
iSeries_tb_recal(void)
441 struct div_result divres
;
442 unsigned long titan
, tb
;
444 /* Make sure we only run on iSeries */
445 if (!firmware_has_feature(FW_FEATURE_ISERIES
))
449 titan
= HvCallXm_loadTod();
450 if ( iSeries_recal_titan
) {
451 unsigned long tb_ticks
= tb
- iSeries_recal_tb
;
452 unsigned long titan_usec
= (titan
- iSeries_recal_titan
) >> 12;
453 unsigned long new_tb_ticks_per_sec
= (tb_ticks
* USEC_PER_SEC
)/titan_usec
;
454 unsigned long new_tb_ticks_per_jiffy
= (new_tb_ticks_per_sec
+(HZ
/2))/HZ
;
455 long tick_diff
= new_tb_ticks_per_jiffy
- tb_ticks_per_jiffy
;
457 /* make sure tb_ticks_per_sec and tb_ticks_per_jiffy are consistent */
458 new_tb_ticks_per_sec
= new_tb_ticks_per_jiffy
* HZ
;
460 if ( tick_diff
< 0 ) {
461 tick_diff
= -tick_diff
;
465 if ( tick_diff
< tb_ticks_per_jiffy
/25 ) {
466 printk( "Titan recalibrate: new tb_ticks_per_jiffy = %lu (%c%ld)\n",
467 new_tb_ticks_per_jiffy
, sign
, tick_diff
);
468 tb_ticks_per_jiffy
= new_tb_ticks_per_jiffy
;
469 tb_ticks_per_sec
= new_tb_ticks_per_sec
;
470 calc_cputime_factors();
471 div128_by_32( XSEC_PER_SEC
, 0, tb_ticks_per_sec
, &divres
);
472 do_gtod
.tb_ticks_per_sec
= tb_ticks_per_sec
;
473 tb_to_xs
= divres
.result_low
;
474 do_gtod
.varp
->tb_to_xs
= tb_to_xs
;
475 vdso_data
->tb_ticks_per_sec
= tb_ticks_per_sec
;
476 vdso_data
->tb_to_xs
= tb_to_xs
;
479 printk( "Titan recalibrate: FAILED (difference > 4 percent)\n"
480 " new tb_ticks_per_jiffy = %lu\n"
481 " old tb_ticks_per_jiffy = %lu\n",
482 new_tb_ticks_per_jiffy
, tb_ticks_per_jiffy
);
486 iSeries_recal_titan
= titan
;
487 iSeries_recal_tb
= tb
;
489 /* Called here as now we know accurate values for the timebase */
493 late_initcall(iSeries_tb_recal
);
495 /* Called from platform early init */
496 void __init
iSeries_time_init_early(void)
498 iSeries_recal_tb
= get_tb();
499 iSeries_recal_titan
= HvCallXm_loadTod();
501 #endif /* CONFIG_PPC_ISERIES */
504 * For iSeries shared processors, we have to let the hypervisor
505 * set the hardware decrementer. We set a virtual decrementer
506 * in the lppaca and call the hypervisor if the virtual
507 * decrementer is less than the current value in the hardware
508 * decrementer. (almost always the new decrementer value will
509 * be greater than the current hardware decementer so the hypervisor
510 * call will not be needed)
514 * timer_interrupt - gets called when the decrementer overflows,
515 * with interrupts disabled.
517 void timer_interrupt(struct pt_regs
* regs
)
519 struct pt_regs
*old_regs
;
521 int cpu
= smp_processor_id();
526 if (atomic_read(&ppc_n_lost_interrupts
) != 0)
530 old_regs
= set_irq_regs(regs
);
533 profile_tick(CPU_PROFILING
);
534 calculate_steal_time();
536 #ifdef CONFIG_PPC_ISERIES
537 if (firmware_has_feature(FW_FEATURE_ISERIES
))
538 get_lppaca()->int_dword
.fields
.decr_int
= 0;
541 while ((ticks
= tb_ticks_since(per_cpu(last_jiffy
, cpu
)))
542 >= tb_ticks_per_jiffy
) {
543 /* Update last_jiffy */
544 per_cpu(last_jiffy
, cpu
) += tb_ticks_per_jiffy
;
545 /* Handle RTCL overflow on 601 */
546 if (__USE_RTC() && per_cpu(last_jiffy
, cpu
) >= 1000000000)
547 per_cpu(last_jiffy
, cpu
) -= 1000000000;
550 * We cannot disable the decrementer, so in the period
551 * between this cpu's being marked offline in cpu_online_map
552 * and calling stop-self, it is taking timer interrupts.
553 * Avoid calling into the scheduler rebalancing code if this
556 if (!cpu_is_offline(cpu
))
557 account_process_time(regs
);
560 * No need to check whether cpu is offline here; boot_cpuid
561 * should have been fixed up by now.
563 if (cpu
!= boot_cpuid
)
566 write_seqlock(&xtime_lock
);
567 tb_next_jiffy
= tb_last_jiffy
+ tb_ticks_per_jiffy
;
568 if (__USE_RTC() && tb_next_jiffy
>= 1000000000)
569 tb_next_jiffy
-= 1000000000;
570 if (per_cpu(last_jiffy
, cpu
) >= tb_next_jiffy
) {
571 tb_last_jiffy
= tb_next_jiffy
;
574 write_sequnlock(&xtime_lock
);
577 next_dec
= tb_ticks_per_jiffy
- ticks
;
580 #ifdef CONFIG_PPC_ISERIES
581 if (firmware_has_feature(FW_FEATURE_ISERIES
) && hvlpevent_is_pending())
582 process_hvlpevents();
586 /* collect purr register values often, for accurate calculations */
587 if (firmware_has_feature(FW_FEATURE_SPLPAR
)) {
588 struct cpu_usage
*cu
= &__get_cpu_var(cpu_usage_array
);
589 cu
->current_tb
= mfspr(SPRN_PURR
);
594 set_irq_regs(old_regs
);
597 void wakeup_decrementer(void)
602 * The timebase gets saved on sleep and restored on wakeup,
603 * so all we need to do is to reset the decrementer.
605 ticks
= tb_ticks_since(__get_cpu_var(last_jiffy
));
606 if (ticks
< tb_ticks_per_jiffy
)
607 ticks
= tb_ticks_per_jiffy
- ticks
;
614 void __init
smp_space_timers(unsigned int max_cpus
)
617 u64 previous_tb
= per_cpu(last_jiffy
, boot_cpuid
);
619 /* make sure tb > per_cpu(last_jiffy, cpu) for all cpus always */
620 previous_tb
-= tb_ticks_per_jiffy
;
622 for_each_possible_cpu(i
) {
625 per_cpu(last_jiffy
, i
) = previous_tb
;
631 * Scheduler clock - returns current time in nanosec units.
633 * Note: mulhdu(a, b) (multiply high double unsigned) returns
634 * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
635 * are 64-bit unsigned numbers.
637 unsigned long long sched_clock(void)
641 return mulhdu(get_tb() - boot_tb
, tb_to_ns_scale
) << tb_to_ns_shift
;
644 static int __init
get_freq(char *name
, int cells
, unsigned long *val
)
646 struct device_node
*cpu
;
647 const unsigned int *fp
;
650 /* The cpu node should have timebase and clock frequency properties */
651 cpu
= of_find_node_by_type(NULL
, "cpu");
654 fp
= of_get_property(cpu
, name
, NULL
);
657 *val
= of_read_ulong(fp
, cells
);
666 void __init
generic_calibrate_decr(void)
668 ppc_tb_freq
= DEFAULT_TB_FREQ
; /* hardcoded default */
670 if (!get_freq("ibm,extended-timebase-frequency", 2, &ppc_tb_freq
) &&
671 !get_freq("timebase-frequency", 1, &ppc_tb_freq
)) {
673 printk(KERN_ERR
"WARNING: Estimating decrementer frequency "
677 ppc_proc_freq
= DEFAULT_PROC_FREQ
; /* hardcoded default */
679 if (!get_freq("ibm,extended-clock-frequency", 2, &ppc_proc_freq
) &&
680 !get_freq("clock-frequency", 1, &ppc_proc_freq
)) {
682 printk(KERN_ERR
"WARNING: Estimating processor frequency "
686 #if defined(CONFIG_BOOKE) || defined(CONFIG_40x)
687 /* Set the time base to zero */
691 /* Clear any pending timer interrupts */
692 mtspr(SPRN_TSR
, TSR_ENW
| TSR_WIS
| TSR_DIS
| TSR_FIS
);
694 /* Enable decrementer interrupt */
695 mtspr(SPRN_TCR
, TCR_DIE
);
699 int update_persistent_clock(struct timespec now
)
703 if (!ppc_md
.set_rtc_time
)
706 to_tm(now
.tv_sec
+ 1 + timezone_offset
, &tm
);
710 return ppc_md
.set_rtc_time(&tm
);
713 unsigned long read_persistent_clock(void)
716 static int first
= 1;
718 /* XXX this is a litle fragile but will work okay in the short term */
721 if (ppc_md
.time_init
)
722 timezone_offset
= ppc_md
.time_init();
724 /* get_boot_time() isn't guaranteed to be safe to call late */
725 if (ppc_md
.get_boot_time
)
726 return ppc_md
.get_boot_time() -timezone_offset
;
728 if (!ppc_md
.get_rtc_time
)
730 ppc_md
.get_rtc_time(&tm
);
731 return mktime(tm
.tm_year
+1900, tm
.tm_mon
+1, tm
.tm_mday
,
732 tm
.tm_hour
, tm
.tm_min
, tm
.tm_sec
);
735 /* clocksource code */
736 static cycle_t
rtc_read(void)
738 return (cycle_t
)get_rtc();
741 static cycle_t
timebase_read(void)
743 return (cycle_t
)get_tb();
746 void update_vsyscall(struct timespec
*wall_time
, struct clocksource
*clock
)
750 if (clock
!= &clocksource_timebase
)
753 /* Make userspace gettimeofday spin until we're done. */
754 ++vdso_data
->tb_update_count
;
757 /* XXX this assumes clock->shift == 22 */
758 /* 4611686018 ~= 2^(20+64-22) / 1e9 */
759 t2x
= (u64
) clock
->mult
* 4611686018ULL;
760 stamp_xsec
= (u64
) xtime
.tv_nsec
* XSEC_PER_SEC
;
761 do_div(stamp_xsec
, 1000000000);
762 stamp_xsec
+= (u64
) xtime
.tv_sec
* XSEC_PER_SEC
;
763 update_gtod(clock
->cycle_last
, stamp_xsec
, t2x
);
766 void update_vsyscall_tz(void)
768 /* Make userspace gettimeofday spin until we're done. */
769 ++vdso_data
->tb_update_count
;
771 vdso_data
->tz_minuteswest
= sys_tz
.tz_minuteswest
;
772 vdso_data
->tz_dsttime
= sys_tz
.tz_dsttime
;
774 ++vdso_data
->tb_update_count
;
777 void __init
clocksource_init(void)
779 struct clocksource
*clock
;
782 clock
= &clocksource_rtc
;
784 clock
= &clocksource_timebase
;
786 clock
->mult
= clocksource_hz2mult(tb_ticks_per_sec
, clock
->shift
);
788 if (clocksource_register(clock
)) {
789 printk(KERN_ERR
"clocksource: %s is already registered\n",
794 printk(KERN_INFO
"clocksource: %s mult[%x] shift[%d] registered\n",
795 clock
->name
, clock
->mult
, clock
->shift
);
798 /* This function is only called on the boot processor */
799 void __init
time_init(void)
802 struct div_result res
;
807 /* 601 processor: dec counts down by 128 every 128ns */
808 ppc_tb_freq
= 1000000000;
809 tb_last_jiffy
= get_rtcl();
811 /* Normal PowerPC with timebase register */
812 ppc_md
.calibrate_decr();
813 printk(KERN_DEBUG
"time_init: decrementer frequency = %lu.%.6lu MHz\n",
814 ppc_tb_freq
/ 1000000, ppc_tb_freq
% 1000000);
815 printk(KERN_DEBUG
"time_init: processor frequency = %lu.%.6lu MHz\n",
816 ppc_proc_freq
/ 1000000, ppc_proc_freq
% 1000000);
817 tb_last_jiffy
= get_tb();
820 tb_ticks_per_jiffy
= ppc_tb_freq
/ HZ
;
821 tb_ticks_per_sec
= ppc_tb_freq
;
822 tb_ticks_per_usec
= ppc_tb_freq
/ 1000000;
823 tb_to_us
= mulhwu_scale_factor(ppc_tb_freq
, 1000000);
824 calc_cputime_factors();
827 * Calculate the length of each tick in ns. It will not be
828 * exactly 1e9/HZ unless ppc_tb_freq is divisible by HZ.
829 * We compute 1e9 * tb_ticks_per_jiffy / ppc_tb_freq,
832 x
= (u64
) NSEC_PER_SEC
* tb_ticks_per_jiffy
+ ppc_tb_freq
- 1;
833 do_div(x
, ppc_tb_freq
);
835 last_tick_len
= x
<< TICKLEN_SCALE
;
838 * Compute ticklen_to_xs, which is a factor which gets multiplied
839 * by (last_tick_len << TICKLEN_SHIFT) to get a tb_to_xs value.
841 * ticklen_to_xs = 2^N / (tb_ticks_per_jiffy * 1e9)
842 * where N = 64 + 20 - TICKLEN_SCALE - TICKLEN_SHIFT
843 * which turns out to be N = 51 - SHIFT_HZ.
844 * This gives the result as a 0.64 fixed-point fraction.
845 * That value is reduced by an offset amounting to 1 xsec per
846 * 2^31 timebase ticks to avoid problems with time going backwards
847 * by 1 xsec when we do timer_recalc_offset due to losing the
848 * fractional xsec. That offset is equal to ppc_tb_freq/2^51
849 * since there are 2^20 xsec in a second.
851 div128_by_32((1ULL << 51) - ppc_tb_freq
, 0,
852 tb_ticks_per_jiffy
<< SHIFT_HZ
, &res
);
853 div128_by_32(res
.result_high
, res
.result_low
, NSEC_PER_SEC
, &res
);
854 ticklen_to_xs
= res
.result_low
;
856 /* Compute tb_to_xs from tick_nsec */
857 tb_to_xs
= mulhdu(last_tick_len
<< TICKLEN_SHIFT
, ticklen_to_xs
);
860 * Compute scale factor for sched_clock.
861 * The calibrate_decr() function has set tb_ticks_per_sec,
862 * which is the timebase frequency.
863 * We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
864 * the 128-bit result as a 64.64 fixed-point number.
865 * We then shift that number right until it is less than 1.0,
866 * giving us the scale factor and shift count to use in
869 div128_by_32(1000000000, 0, tb_ticks_per_sec
, &res
);
870 scale
= res
.result_low
;
871 for (shift
= 0; res
.result_high
!= 0; ++shift
) {
872 scale
= (scale
>> 1) | (res
.result_high
<< 63);
873 res
.result_high
>>= 1;
875 tb_to_ns_scale
= scale
;
876 tb_to_ns_shift
= shift
;
877 /* Save the current timebase to pretty up CONFIG_PRINTK_TIME */
878 boot_tb
= get_tb_or_rtc();
880 write_seqlock_irqsave(&xtime_lock
, flags
);
882 /* If platform provided a timezone (pmac), we correct the time */
883 if (timezone_offset
) {
884 sys_tz
.tz_minuteswest
= -timezone_offset
/ 60;
885 sys_tz
.tz_dsttime
= 0;
888 do_gtod
.varp
= &do_gtod
.vars
[0];
890 do_gtod
.varp
->tb_orig_stamp
= tb_last_jiffy
;
891 __get_cpu_var(last_jiffy
) = tb_last_jiffy
;
892 do_gtod
.varp
->stamp_xsec
= (u64
) xtime
.tv_sec
* XSEC_PER_SEC
;
893 do_gtod
.tb_ticks_per_sec
= tb_ticks_per_sec
;
894 do_gtod
.varp
->tb_to_xs
= tb_to_xs
;
895 do_gtod
.tb_to_us
= tb_to_us
;
897 vdso_data
->tb_orig_stamp
= tb_last_jiffy
;
898 vdso_data
->tb_update_count
= 0;
899 vdso_data
->tb_ticks_per_sec
= tb_ticks_per_sec
;
900 vdso_data
->stamp_xsec
= (u64
) xtime
.tv_sec
* XSEC_PER_SEC
;
901 vdso_data
->tb_to_xs
= tb_to_xs
;
905 write_sequnlock_irqrestore(&xtime_lock
, flags
);
907 /* Register the clocksource, if we're not running on iSeries */
908 if (!firmware_has_feature(FW_FEATURE_ISERIES
))
911 /* Not exact, but the timer interrupt takes care of this */
912 set_dec(tb_ticks_per_jiffy
);
917 #define STARTOFTIME 1970
918 #define SECDAY 86400L
919 #define SECYR (SECDAY * 365)
920 #define leapyear(year) ((year) % 4 == 0 && \
921 ((year) % 100 != 0 || (year) % 400 == 0))
922 #define days_in_year(a) (leapyear(a) ? 366 : 365)
923 #define days_in_month(a) (month_days[(a) - 1])
925 static int month_days
[12] = {
926 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
930 * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
932 void GregorianDay(struct rtc_time
* tm
)
937 int MonthOffset
[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
939 lastYear
= tm
->tm_year
- 1;
942 * Number of leap corrections to apply up to end of last year
944 leapsToDate
= lastYear
/ 4 - lastYear
/ 100 + lastYear
/ 400;
947 * This year is a leap year if it is divisible by 4 except when it is
948 * divisible by 100 unless it is divisible by 400
950 * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 was
952 day
= tm
->tm_mon
> 2 && leapyear(tm
->tm_year
);
954 day
+= lastYear
*365 + leapsToDate
+ MonthOffset
[tm
->tm_mon
-1] +
957 tm
->tm_wday
= day
% 7;
960 void to_tm(int tim
, struct rtc_time
* tm
)
963 register long hms
, day
;
968 /* Hours, minutes, seconds are easy */
969 tm
->tm_hour
= hms
/ 3600;
970 tm
->tm_min
= (hms
% 3600) / 60;
971 tm
->tm_sec
= (hms
% 3600) % 60;
973 /* Number of years in days */
974 for (i
= STARTOFTIME
; day
>= days_in_year(i
); i
++)
975 day
-= days_in_year(i
);
978 /* Number of months in days left */
979 if (leapyear(tm
->tm_year
))
980 days_in_month(FEBRUARY
) = 29;
981 for (i
= 1; day
>= days_in_month(i
); i
++)
982 day
-= days_in_month(i
);
983 days_in_month(FEBRUARY
) = 28;
986 /* Days are what is left over (+1) from all that. */
987 tm
->tm_mday
= day
+ 1;
990 * Determine the day of week
995 /* Auxiliary function to compute scaling factors */
996 /* Actually the choice of a timebase running at 1/4 the of the bus
997 * frequency giving resolution of a few tens of nanoseconds is quite nice.
998 * It makes this computation very precise (27-28 bits typically) which
999 * is optimistic considering the stability of most processor clock
1000 * oscillators and the precision with which the timebase frequency
1001 * is measured but does not harm.
1003 unsigned mulhwu_scale_factor(unsigned inscale
, unsigned outscale
)
1005 unsigned mlt
=0, tmp
, err
;
1006 /* No concern for performance, it's done once: use a stupid
1007 * but safe and compact method to find the multiplier.
1010 for (tmp
= 1U<<31; tmp
!= 0; tmp
>>= 1) {
1011 if (mulhwu(inscale
, mlt
|tmp
) < outscale
)
1015 /* We might still be off by 1 for the best approximation.
1016 * A side effect of this is that if outscale is too large
1017 * the returned value will be zero.
1018 * Many corner cases have been checked and seem to work,
1019 * some might have been forgotten in the test however.
1022 err
= inscale
* (mlt
+1);
1023 if (err
<= inscale
/2)
1029 * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
1032 void div128_by_32(u64 dividend_high
, u64 dividend_low
,
1033 unsigned divisor
, struct div_result
*dr
)
1035 unsigned long a
, b
, c
, d
;
1036 unsigned long w
, x
, y
, z
;
1039 a
= dividend_high
>> 32;
1040 b
= dividend_high
& 0xffffffff;
1041 c
= dividend_low
>> 32;
1042 d
= dividend_low
& 0xffffffff;
1045 ra
= ((u64
)(a
- (w
* divisor
)) << 32) + b
;
1047 rb
= ((u64
) do_div(ra
, divisor
) << 32) + c
;
1050 rc
= ((u64
) do_div(rb
, divisor
) << 32) + d
;
1053 do_div(rc
, divisor
);
1056 dr
->result_high
= ((u64
)w
<< 32) + x
;
1057 dr
->result_low
= ((u64
)y
<< 32) + z
;