2 * Common time routines among all ppc machines.
4 * Written by Cort Dougan (cort@cs.nmt.edu) to merge
5 * Paul Mackerras' version and mine for PReP and Pmac.
6 * MPC8xx/MBX changes by Dan Malek (dmalek@jlc.net).
7 * Converted for 64-bit by Mike Corrigan (mikejc@us.ibm.com)
9 * First round of bugfixes by Gabriel Paubert (paubert@iram.es)
10 * to make clock more stable (2.4.0-test5). The only thing
11 * that this code assumes is that the timebases have been synchronized
12 * by firmware on SMP and are never stopped (never do sleep
13 * on SMP then, nap and doze are OK).
15 * Speeded up do_gettimeofday by getting rid of references to
16 * xtime (which required locks for consistency). (mikejc@us.ibm.com)
18 * TODO (not necessarily in this file):
19 * - improve precision and reproducibility of timebase frequency
20 * measurement at boot time. (for iSeries, we calibrate the timebase
21 * against the Titan chip's clock.)
22 * - for astronomical applications: add a new function to get
23 * non ambiguous timestamps even around leap seconds. This needs
24 * a new timestamp format and a good name.
26 * 1997-09-10 Updated NTP code according to technical memorandum Jan '96
27 * "A Kernel Model for Precision Timekeeping" by Dave Mills
29 * This program is free software; you can redistribute it and/or
30 * modify it under the terms of the GNU General Public License
31 * as published by the Free Software Foundation; either version
32 * 2 of the License, or (at your option) any later version.
35 #include <linux/config.h>
36 #include <linux/errno.h>
37 #include <linux/module.h>
38 #include <linux/sched.h>
39 #include <linux/kernel.h>
40 #include <linux/param.h>
41 #include <linux/string.h>
43 #include <linux/interrupt.h>
44 #include <linux/timex.h>
45 #include <linux/kernel_stat.h>
46 #include <linux/time.h>
47 #include <linux/init.h>
48 #include <linux/profile.h>
49 #include <linux/cpu.h>
50 #include <linux/security.h>
51 #include <linux/percpu.h>
52 #include <linux/rtc.h>
53 #include <linux/jiffies.h>
56 #include <asm/processor.h>
57 #include <asm/nvram.h>
58 #include <asm/cache.h>
59 #include <asm/machdep.h>
60 #include <asm/uaccess.h>
64 #include <asm/div64.h>
66 #include <asm/vdso_datapage.h>
68 #include <asm/firmware.h>
70 #ifdef CONFIG_PPC_ISERIES
71 #include <asm/iseries/it_lp_queue.h>
72 #include <asm/iseries/hv_call_xm.h>
76 /* keep track of when we need to update the rtc */
77 time_t last_rtc_update
;
78 extern int piranha_simulator
;
79 #ifdef CONFIG_PPC_ISERIES
80 unsigned long iSeries_recal_titan
= 0;
81 unsigned long iSeries_recal_tb
= 0;
82 static unsigned long first_settimeofday
= 1;
85 /* The decrementer counts down by 128 every 128ns on a 601. */
86 #define DECREMENTER_COUNT_601 (1000000000 / HZ)
88 #define XSEC_PER_SEC (1024*1024)
91 #define SCALE_XSEC(xsec, max) (((xsec) * max) / XSEC_PER_SEC)
93 /* compute ((xsec << 12) * max) >> 32 */
94 #define SCALE_XSEC(xsec, max) mulhwu((xsec) << 12, max)
97 unsigned long tb_ticks_per_jiffy
;
98 unsigned long tb_ticks_per_usec
= 100; /* sane default */
99 EXPORT_SYMBOL(tb_ticks_per_usec
);
100 unsigned long tb_ticks_per_sec
;
104 #define TICKLEN_SCALE (SHIFT_SCALE - 10)
105 u64 last_tick_len
; /* units are ns / 2^TICKLEN_SCALE */
106 u64 ticklen_to_xs
; /* 0.64 fraction */
108 /* If last_tick_len corresponds to about 1/HZ seconds, then
109 last_tick_len << TICKLEN_SHIFT will be about 2^63. */
110 #define TICKLEN_SHIFT (63 - 30 - TICKLEN_SCALE + SHIFT_HZ)
112 DEFINE_SPINLOCK(rtc_lock
);
113 EXPORT_SYMBOL_GPL(rtc_lock
);
116 unsigned tb_to_ns_shift
;
118 struct gettimeofday_struct do_gtod
;
120 extern unsigned long wall_jiffies
;
122 extern struct timezone sys_tz
;
123 static long timezone_offset
;
125 unsigned long ppc_proc_freq
;
126 unsigned long ppc_tb_freq
;
128 u64 tb_last_jiffy __cacheline_aligned_in_smp
;
129 unsigned long tb_last_stamp
;
132 * Note that on ppc32 this only stores the bottom 32 bits of
133 * the timebase value, but that's enough to tell when a jiffy
136 DEFINE_PER_CPU(unsigned long, last_jiffy
);
138 void __delay(unsigned long loops
)
146 /* the RTCL register wraps at 1000000000 */
147 diff
= get_rtcl() - start
;
150 } while (diff
< loops
);
153 while (get_tbl() - start
< loops
)
158 EXPORT_SYMBOL(__delay
);
160 void udelay(unsigned long usecs
)
162 __delay(tb_ticks_per_usec
* usecs
);
164 EXPORT_SYMBOL(udelay
);
166 static __inline__
void timer_check_rtc(void)
169 * update the rtc when needed, this should be performed on the
170 * right fraction of a second. Half or full second ?
171 * Full second works on mk48t59 clocks, others need testing.
172 * Note that this update is basically only used through
173 * the adjtimex system calls. Setting the HW clock in
174 * any other way is a /dev/rtc and userland business.
175 * This is still wrong by -0.5/+1.5 jiffies because of the
176 * timer interrupt resolution and possible delay, but here we
177 * hit a quantization limit which can only be solved by higher
178 * resolution timers and decoupling time management from timer
179 * interrupts. This is also wrong on the clocks
180 * which require being written at the half second boundary.
181 * We should have an rtc call that only sets the minutes and
182 * seconds like on Intel to avoid problems with non UTC clocks.
184 if (ppc_md
.set_rtc_time
&& ntp_synced() &&
185 xtime
.tv_sec
- last_rtc_update
>= 659 &&
186 abs((xtime
.tv_nsec
/1000) - (1000000-1000000/HZ
)) < 500000/HZ
) {
188 to_tm(xtime
.tv_sec
+ 1 + timezone_offset
, &tm
);
191 if (ppc_md
.set_rtc_time(&tm
) == 0)
192 last_rtc_update
= xtime
.tv_sec
+ 1;
194 /* Try again one minute later */
195 last_rtc_update
+= 60;
200 * This version of gettimeofday has microsecond resolution.
202 static inline void __do_gettimeofday(struct timeval
*tv
, u64 tb_val
)
204 unsigned long sec
, usec
;
206 struct gettimeofday_vars
*temp_varp
;
207 u64 temp_tb_to_xs
, temp_stamp_xsec
;
210 * These calculations are faster (gets rid of divides)
211 * if done in units of 1/2^20 rather than microseconds.
212 * The conversion to microseconds at the end is done
213 * without a divide (and in fact, without a multiply)
215 temp_varp
= do_gtod
.varp
;
216 tb_ticks
= tb_val
- temp_varp
->tb_orig_stamp
;
217 temp_tb_to_xs
= temp_varp
->tb_to_xs
;
218 temp_stamp_xsec
= temp_varp
->stamp_xsec
;
219 xsec
= temp_stamp_xsec
+ mulhdu(tb_ticks
, temp_tb_to_xs
);
220 sec
= xsec
/ XSEC_PER_SEC
;
221 usec
= (unsigned long)xsec
& (XSEC_PER_SEC
- 1);
222 usec
= SCALE_XSEC(usec
, 1000000);
228 void do_gettimeofday(struct timeval
*tv
)
231 /* do this the old way */
232 unsigned long flags
, seq
;
233 unsigned int sec
, nsec
, usec
;
236 seq
= read_seqbegin_irqsave(&xtime_lock
, flags
);
238 nsec
= xtime
.tv_nsec
+ tb_ticks_since(tb_last_stamp
);
239 } while (read_seqretry_irqrestore(&xtime_lock
, seq
, flags
));
241 while (usec
>= 1000000) {
249 __do_gettimeofday(tv
, get_tb());
252 EXPORT_SYMBOL(do_gettimeofday
);
255 * There are two copies of tb_to_xs and stamp_xsec so that no
256 * lock is needed to access and use these values in
257 * do_gettimeofday. We alternate the copies and as long as a
258 * reasonable time elapses between changes, there will never
259 * be inconsistent values. ntpd has a minimum of one minute
262 static inline void update_gtod(u64 new_tb_stamp
, u64 new_stamp_xsec
,
266 struct gettimeofday_vars
*temp_varp
;
268 temp_idx
= (do_gtod
.var_idx
== 0);
269 temp_varp
= &do_gtod
.vars
[temp_idx
];
271 temp_varp
->tb_to_xs
= new_tb_to_xs
;
272 temp_varp
->tb_orig_stamp
= new_tb_stamp
;
273 temp_varp
->stamp_xsec
= new_stamp_xsec
;
275 do_gtod
.varp
= temp_varp
;
276 do_gtod
.var_idx
= temp_idx
;
279 * tb_update_count is used to allow the userspace gettimeofday code
280 * to assure itself that it sees a consistent view of the tb_to_xs and
281 * stamp_xsec variables. It reads the tb_update_count, then reads
282 * tb_to_xs and stamp_xsec and then reads tb_update_count again. If
283 * the two values of tb_update_count match and are even then the
284 * tb_to_xs and stamp_xsec values are consistent. If not, then it
285 * loops back and reads them again until this criteria is met.
286 * We expect the caller to have done the first increment of
287 * vdso_data->tb_update_count already.
289 vdso_data
->tb_orig_stamp
= new_tb_stamp
;
290 vdso_data
->stamp_xsec
= new_stamp_xsec
;
291 vdso_data
->tb_to_xs
= new_tb_to_xs
;
292 vdso_data
->wtom_clock_sec
= wall_to_monotonic
.tv_sec
;
293 vdso_data
->wtom_clock_nsec
= wall_to_monotonic
.tv_nsec
;
295 ++(vdso_data
->tb_update_count
);
299 * When the timebase - tb_orig_stamp gets too big, we do a manipulation
300 * between tb_orig_stamp and stamp_xsec. The goal here is to keep the
301 * difference tb - tb_orig_stamp small enough to always fit inside a
302 * 32 bits number. This is a requirement of our fast 32 bits userland
303 * implementation in the vdso. If we "miss" a call to this function
304 * (interrupt latency, CPU locked in a spinlock, ...) and we end up
305 * with a too big difference, then the vdso will fallback to calling
308 static __inline__
void timer_recalc_offset(u64 cur_tb
)
310 unsigned long offset
;
313 u64 tb
, xsec_old
, xsec_new
;
314 struct gettimeofday_vars
*varp
;
318 tlen
= current_tick_length();
319 offset
= cur_tb
- do_gtod
.varp
->tb_orig_stamp
;
320 if (tlen
== last_tick_len
&& offset
< 0x80000000u
)
322 if (tlen
!= last_tick_len
) {
323 t2x
= mulhdu(tlen
<< TICKLEN_SHIFT
, ticklen_to_xs
);
324 last_tick_len
= tlen
;
326 t2x
= do_gtod
.varp
->tb_to_xs
;
327 new_stamp_xsec
= (u64
) xtime
.tv_nsec
* XSEC_PER_SEC
;
328 do_div(new_stamp_xsec
, 1000000000);
329 new_stamp_xsec
+= (u64
) xtime
.tv_sec
* XSEC_PER_SEC
;
331 ++vdso_data
->tb_update_count
;
335 * Make sure time doesn't go backwards for userspace gettimeofday.
339 xsec_old
= mulhdu(tb
- varp
->tb_orig_stamp
, varp
->tb_to_xs
)
341 xsec_new
= mulhdu(tb
- cur_tb
, t2x
) + new_stamp_xsec
;
342 if (xsec_new
< xsec_old
)
343 new_stamp_xsec
+= xsec_old
- xsec_new
;
345 update_gtod(cur_tb
, new_stamp_xsec
, t2x
);
349 unsigned long profile_pc(struct pt_regs
*regs
)
351 unsigned long pc
= instruction_pointer(regs
);
353 if (in_lock_functions(pc
))
358 EXPORT_SYMBOL(profile_pc
);
361 #ifdef CONFIG_PPC_ISERIES
364 * This function recalibrates the timebase based on the 49-bit time-of-day
365 * value in the Titan chip. The Titan is much more accurate than the value
366 * returned by the service processor for the timebase frequency.
369 static void iSeries_tb_recal(void)
371 struct div_result divres
;
372 unsigned long titan
, tb
;
374 titan
= HvCallXm_loadTod();
375 if ( iSeries_recal_titan
) {
376 unsigned long tb_ticks
= tb
- iSeries_recal_tb
;
377 unsigned long titan_usec
= (titan
- iSeries_recal_titan
) >> 12;
378 unsigned long new_tb_ticks_per_sec
= (tb_ticks
* USEC_PER_SEC
)/titan_usec
;
379 unsigned long new_tb_ticks_per_jiffy
= (new_tb_ticks_per_sec
+(HZ
/2))/HZ
;
380 long tick_diff
= new_tb_ticks_per_jiffy
- tb_ticks_per_jiffy
;
382 /* make sure tb_ticks_per_sec and tb_ticks_per_jiffy are consistent */
383 new_tb_ticks_per_sec
= new_tb_ticks_per_jiffy
* HZ
;
385 if ( tick_diff
< 0 ) {
386 tick_diff
= -tick_diff
;
390 if ( tick_diff
< tb_ticks_per_jiffy
/25 ) {
391 printk( "Titan recalibrate: new tb_ticks_per_jiffy = %lu (%c%ld)\n",
392 new_tb_ticks_per_jiffy
, sign
, tick_diff
);
393 tb_ticks_per_jiffy
= new_tb_ticks_per_jiffy
;
394 tb_ticks_per_sec
= new_tb_ticks_per_sec
;
395 div128_by_32( XSEC_PER_SEC
, 0, tb_ticks_per_sec
, &divres
);
396 do_gtod
.tb_ticks_per_sec
= tb_ticks_per_sec
;
397 tb_to_xs
= divres
.result_low
;
398 do_gtod
.varp
->tb_to_xs
= tb_to_xs
;
399 vdso_data
->tb_ticks_per_sec
= tb_ticks_per_sec
;
400 vdso_data
->tb_to_xs
= tb_to_xs
;
403 printk( "Titan recalibrate: FAILED (difference > 4 percent)\n"
404 " new tb_ticks_per_jiffy = %lu\n"
405 " old tb_ticks_per_jiffy = %lu\n",
406 new_tb_ticks_per_jiffy
, tb_ticks_per_jiffy
);
410 iSeries_recal_titan
= titan
;
411 iSeries_recal_tb
= tb
;
416 * For iSeries shared processors, we have to let the hypervisor
417 * set the hardware decrementer. We set a virtual decrementer
418 * in the lppaca and call the hypervisor if the virtual
419 * decrementer is less than the current value in the hardware
420 * decrementer. (almost always the new decrementer value will
421 * be greater than the current hardware decementer so the hypervisor
422 * call will not be needed)
426 * timer_interrupt - gets called when the decrementer overflows,
427 * with interrupts disabled.
429 void timer_interrupt(struct pt_regs
* regs
)
432 int cpu
= smp_processor_id();
436 if (atomic_read(&ppc_n_lost_interrupts
) != 0)
442 profile_tick(CPU_PROFILING
, regs
);
444 #ifdef CONFIG_PPC_ISERIES
445 get_lppaca()->int_dword
.fields
.decr_int
= 0;
448 while ((ticks
= tb_ticks_since(per_cpu(last_jiffy
, cpu
)))
449 >= tb_ticks_per_jiffy
) {
450 /* Update last_jiffy */
451 per_cpu(last_jiffy
, cpu
) += tb_ticks_per_jiffy
;
452 /* Handle RTCL overflow on 601 */
453 if (__USE_RTC() && per_cpu(last_jiffy
, cpu
) >= 1000000000)
454 per_cpu(last_jiffy
, cpu
) -= 1000000000;
457 * We cannot disable the decrementer, so in the period
458 * between this cpu's being marked offline in cpu_online_map
459 * and calling stop-self, it is taking timer interrupts.
460 * Avoid calling into the scheduler rebalancing code if this
463 if (!cpu_is_offline(cpu
))
464 update_process_times(user_mode(regs
));
467 * No need to check whether cpu is offline here; boot_cpuid
468 * should have been fixed up by now.
470 if (cpu
!= boot_cpuid
)
473 write_seqlock(&xtime_lock
);
474 tb_last_jiffy
+= tb_ticks_per_jiffy
;
475 tb_last_stamp
= per_cpu(last_jiffy
, cpu
);
477 timer_recalc_offset(tb_last_jiffy
);
479 write_sequnlock(&xtime_lock
);
482 next_dec
= tb_ticks_per_jiffy
- ticks
;
485 #ifdef CONFIG_PPC_ISERIES
486 if (hvlpevent_is_pending())
487 process_hvlpevents(regs
);
491 /* collect purr register values often, for accurate calculations */
492 if (firmware_has_feature(FW_FEATURE_SPLPAR
)) {
493 struct cpu_usage
*cu
= &__get_cpu_var(cpu_usage_array
);
494 cu
->current_tb
= mfspr(SPRN_PURR
);
501 void wakeup_decrementer(void)
506 * The timebase gets saved on sleep and restored on wakeup,
507 * so all we need to do is to reset the decrementer.
509 ticks
= tb_ticks_since(__get_cpu_var(last_jiffy
));
510 if (ticks
< tb_ticks_per_jiffy
)
511 ticks
= tb_ticks_per_jiffy
- ticks
;
518 void __init
smp_space_timers(unsigned int max_cpus
)
521 unsigned long offset
= tb_ticks_per_jiffy
/ max_cpus
;
522 unsigned long previous_tb
= per_cpu(last_jiffy
, boot_cpuid
);
524 /* make sure tb > per_cpu(last_jiffy, cpu) for all cpus always */
525 previous_tb
-= tb_ticks_per_jiffy
;
527 if (i
!= boot_cpuid
) {
528 previous_tb
+= offset
;
529 per_cpu(last_jiffy
, i
) = previous_tb
;
536 * Scheduler clock - returns current time in nanosec units.
538 * Note: mulhdu(a, b) (multiply high double unsigned) returns
539 * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
540 * are 64-bit unsigned numbers.
542 unsigned long long sched_clock(void)
546 return mulhdu(get_tb(), tb_to_ns_scale
) << tb_to_ns_shift
;
549 int do_settimeofday(struct timespec
*tv
)
551 time_t wtm_sec
, new_sec
= tv
->tv_sec
;
552 long wtm_nsec
, new_nsec
= tv
->tv_nsec
;
555 unsigned long tb_delta
;
557 if ((unsigned long)tv
->tv_nsec
>= NSEC_PER_SEC
)
560 write_seqlock_irqsave(&xtime_lock
, flags
);
563 * Updating the RTC is not the job of this code. If the time is
564 * stepped under NTP, the RTC will be updated after STA_UNSYNC
565 * is cleared. Tools like clock/hwclock either copy the RTC
566 * to the system time, in which case there is no point in writing
567 * to the RTC again, or write to the RTC but then they don't call
568 * settimeofday to perform this operation.
570 #ifdef CONFIG_PPC_ISERIES
571 if (first_settimeofday
) {
573 first_settimeofday
= 0;
577 /* Make userspace gettimeofday spin until we're done. */
578 ++vdso_data
->tb_update_count
;
582 * Subtract off the number of nanoseconds since the
583 * beginning of the last tick.
584 * Note that since we don't increment jiffies_64 anywhere other
585 * than in do_timer (since we don't have a lost tick problem),
586 * wall_jiffies will always be the same as jiffies,
587 * and therefore the (jiffies - wall_jiffies) computation
590 tb_delta
= tb_ticks_since(tb_last_stamp
);
591 tb_delta
= mulhdu(tb_delta
, do_gtod
.varp
->tb_to_xs
); /* in xsec */
592 new_nsec
-= SCALE_XSEC(tb_delta
, 1000000000);
594 wtm_sec
= wall_to_monotonic
.tv_sec
+ (xtime
.tv_sec
- new_sec
);
595 wtm_nsec
= wall_to_monotonic
.tv_nsec
+ (xtime
.tv_nsec
- new_nsec
);
597 set_normalized_timespec(&xtime
, new_sec
, new_nsec
);
598 set_normalized_timespec(&wall_to_monotonic
, wtm_sec
, wtm_nsec
);
600 /* In case of a large backwards jump in time with NTP, we want the
601 * clock to be updated as soon as the PLL is again in lock.
603 last_rtc_update
= new_sec
- 658;
607 new_xsec
= xtime
.tv_nsec
;
609 new_xsec
*= XSEC_PER_SEC
;
610 do_div(new_xsec
, NSEC_PER_SEC
);
612 new_xsec
+= (u64
)xtime
.tv_sec
* XSEC_PER_SEC
;
613 update_gtod(tb_last_jiffy
, new_xsec
, do_gtod
.varp
->tb_to_xs
);
615 vdso_data
->tz_minuteswest
= sys_tz
.tz_minuteswest
;
616 vdso_data
->tz_dsttime
= sys_tz
.tz_dsttime
;
618 write_sequnlock_irqrestore(&xtime_lock
, flags
);
623 EXPORT_SYMBOL(do_settimeofday
);
625 void __init
generic_calibrate_decr(void)
627 struct device_node
*cpu
;
632 * The cpu node should have a timebase-frequency property
633 * to tell us the rate at which the decrementer counts.
635 cpu
= of_find_node_by_type(NULL
, "cpu");
637 ppc_tb_freq
= DEFAULT_TB_FREQ
; /* hardcoded default */
640 fp
= (unsigned int *)get_property(cpu
, "timebase-frequency",
648 printk(KERN_ERR
"WARNING: Estimating decrementer frequency "
651 ppc_proc_freq
= DEFAULT_PROC_FREQ
;
654 fp
= (unsigned int *)get_property(cpu
, "clock-frequency",
662 /* Set the time base to zero */
666 /* Clear any pending timer interrupts */
667 mtspr(SPRN_TSR
, TSR_ENW
| TSR_WIS
| TSR_DIS
| TSR_FIS
);
669 /* Enable decrementer interrupt */
670 mtspr(SPRN_TCR
, TCR_DIE
);
673 printk(KERN_ERR
"WARNING: Estimating processor frequency "
679 unsigned long get_boot_time(void)
683 if (ppc_md
.get_boot_time
)
684 return ppc_md
.get_boot_time();
685 if (!ppc_md
.get_rtc_time
)
687 ppc_md
.get_rtc_time(&tm
);
688 return mktime(tm
.tm_year
+1900, tm
.tm_mon
+1, tm
.tm_mday
,
689 tm
.tm_hour
, tm
.tm_min
, tm
.tm_sec
);
692 /* This function is only called on the boot processor */
693 void __init
time_init(void)
696 unsigned long tm
= 0;
697 struct div_result res
;
701 if (ppc_md
.time_init
!= NULL
)
702 timezone_offset
= ppc_md
.time_init();
705 /* 601 processor: dec counts down by 128 every 128ns */
706 ppc_tb_freq
= 1000000000;
707 tb_last_stamp
= get_rtcl();
708 tb_last_jiffy
= tb_last_stamp
;
710 /* Normal PowerPC with timebase register */
711 ppc_md
.calibrate_decr();
712 printk(KERN_INFO
"time_init: decrementer frequency = %lu.%.6lu MHz\n",
713 ppc_tb_freq
/ 1000000, ppc_tb_freq
% 1000000);
714 printk(KERN_INFO
"time_init: processor frequency = %lu.%.6lu MHz\n",
715 ppc_proc_freq
/ 1000000, ppc_proc_freq
% 1000000);
716 tb_last_stamp
= tb_last_jiffy
= get_tb();
719 tb_ticks_per_jiffy
= ppc_tb_freq
/ HZ
;
720 tb_ticks_per_sec
= ppc_tb_freq
;
721 tb_ticks_per_usec
= ppc_tb_freq
/ 1000000;
722 tb_to_us
= mulhwu_scale_factor(ppc_tb_freq
, 1000000);
725 * Calculate the length of each tick in ns. It will not be
726 * exactly 1e9/HZ unless ppc_tb_freq is divisible by HZ.
727 * We compute 1e9 * tb_ticks_per_jiffy / ppc_tb_freq,
730 x
= (u64
) NSEC_PER_SEC
* tb_ticks_per_jiffy
+ ppc_tb_freq
- 1;
731 do_div(x
, ppc_tb_freq
);
733 last_tick_len
= x
<< TICKLEN_SCALE
;
736 * Compute ticklen_to_xs, which is a factor which gets multiplied
737 * by (last_tick_len << TICKLEN_SHIFT) to get a tb_to_xs value.
739 * ticklen_to_xs = 2^N / (tb_ticks_per_jiffy * 1e9)
740 * where N = 64 + 20 - TICKLEN_SCALE - TICKLEN_SHIFT
741 * which turns out to be N = 51 - SHIFT_HZ.
742 * This gives the result as a 0.64 fixed-point fraction.
743 * That value is reduced by an offset amounting to 1 xsec per
744 * 2^31 timebase ticks to avoid problems with time going backwards
745 * by 1 xsec when we do timer_recalc_offset due to losing the
746 * fractional xsec. That offset is equal to ppc_tb_freq/2^51
747 * since there are 2^20 xsec in a second.
749 div128_by_32((1ULL << 51) - ppc_tb_freq
, 0,
750 tb_ticks_per_jiffy
<< SHIFT_HZ
, &res
);
751 div128_by_32(res
.result_high
, res
.result_low
, NSEC_PER_SEC
, &res
);
752 ticklen_to_xs
= res
.result_low
;
754 /* Compute tb_to_xs from tick_nsec */
755 tb_to_xs
= mulhdu(last_tick_len
<< TICKLEN_SHIFT
, ticklen_to_xs
);
758 * Compute scale factor for sched_clock.
759 * The calibrate_decr() function has set tb_ticks_per_sec,
760 * which is the timebase frequency.
761 * We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
762 * the 128-bit result as a 64.64 fixed-point number.
763 * We then shift that number right until it is less than 1.0,
764 * giving us the scale factor and shift count to use in
767 div128_by_32(1000000000, 0, tb_ticks_per_sec
, &res
);
768 scale
= res
.result_low
;
769 for (shift
= 0; res
.result_high
!= 0; ++shift
) {
770 scale
= (scale
>> 1) | (res
.result_high
<< 63);
771 res
.result_high
>>= 1;
773 tb_to_ns_scale
= scale
;
774 tb_to_ns_shift
= shift
;
776 #ifdef CONFIG_PPC_ISERIES
777 if (!piranha_simulator
)
779 tm
= get_boot_time();
781 write_seqlock_irqsave(&xtime_lock
, flags
);
783 /* If platform provided a timezone (pmac), we correct the time */
784 if (timezone_offset
) {
785 sys_tz
.tz_minuteswest
= -timezone_offset
/ 60;
786 sys_tz
.tz_dsttime
= 0;
787 tm
-= timezone_offset
;
792 do_gtod
.varp
= &do_gtod
.vars
[0];
794 do_gtod
.varp
->tb_orig_stamp
= tb_last_jiffy
;
795 __get_cpu_var(last_jiffy
) = tb_last_stamp
;
796 do_gtod
.varp
->stamp_xsec
= (u64
) xtime
.tv_sec
* XSEC_PER_SEC
;
797 do_gtod
.tb_ticks_per_sec
= tb_ticks_per_sec
;
798 do_gtod
.varp
->tb_to_xs
= tb_to_xs
;
799 do_gtod
.tb_to_us
= tb_to_us
;
801 vdso_data
->tb_orig_stamp
= tb_last_jiffy
;
802 vdso_data
->tb_update_count
= 0;
803 vdso_data
->tb_ticks_per_sec
= tb_ticks_per_sec
;
804 vdso_data
->stamp_xsec
= (u64
) xtime
.tv_sec
* XSEC_PER_SEC
;
805 vdso_data
->tb_to_xs
= tb_to_xs
;
809 last_rtc_update
= xtime
.tv_sec
;
810 set_normalized_timespec(&wall_to_monotonic
,
811 -xtime
.tv_sec
, -xtime
.tv_nsec
);
812 write_sequnlock_irqrestore(&xtime_lock
, flags
);
814 /* Not exact, but the timer interrupt takes care of this */
815 set_dec(tb_ticks_per_jiffy
);
820 #define STARTOFTIME 1970
821 #define SECDAY 86400L
822 #define SECYR (SECDAY * 365)
823 #define leapyear(year) ((year) % 4 == 0 && \
824 ((year) % 100 != 0 || (year) % 400 == 0))
825 #define days_in_year(a) (leapyear(a) ? 366 : 365)
826 #define days_in_month(a) (month_days[(a) - 1])
828 static int month_days
[12] = {
829 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
833 * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
835 void GregorianDay(struct rtc_time
* tm
)
840 int MonthOffset
[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
842 lastYear
= tm
->tm_year
- 1;
845 * Number of leap corrections to apply up to end of last year
847 leapsToDate
= lastYear
/ 4 - lastYear
/ 100 + lastYear
/ 400;
850 * This year is a leap year if it is divisible by 4 except when it is
851 * divisible by 100 unless it is divisible by 400
853 * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 was
855 day
= tm
->tm_mon
> 2 && leapyear(tm
->tm_year
);
857 day
+= lastYear
*365 + leapsToDate
+ MonthOffset
[tm
->tm_mon
-1] +
860 tm
->tm_wday
= day
% 7;
863 void to_tm(int tim
, struct rtc_time
* tm
)
866 register long hms
, day
;
871 /* Hours, minutes, seconds are easy */
872 tm
->tm_hour
= hms
/ 3600;
873 tm
->tm_min
= (hms
% 3600) / 60;
874 tm
->tm_sec
= (hms
% 3600) % 60;
876 /* Number of years in days */
877 for (i
= STARTOFTIME
; day
>= days_in_year(i
); i
++)
878 day
-= days_in_year(i
);
881 /* Number of months in days left */
882 if (leapyear(tm
->tm_year
))
883 days_in_month(FEBRUARY
) = 29;
884 for (i
= 1; day
>= days_in_month(i
); i
++)
885 day
-= days_in_month(i
);
886 days_in_month(FEBRUARY
) = 28;
889 /* Days are what is left over (+1) from all that. */
890 tm
->tm_mday
= day
+ 1;
893 * Determine the day of week
898 /* Auxiliary function to compute scaling factors */
899 /* Actually the choice of a timebase running at 1/4 the of the bus
900 * frequency giving resolution of a few tens of nanoseconds is quite nice.
901 * It makes this computation very precise (27-28 bits typically) which
902 * is optimistic considering the stability of most processor clock
903 * oscillators and the precision with which the timebase frequency
904 * is measured but does not harm.
906 unsigned mulhwu_scale_factor(unsigned inscale
, unsigned outscale
)
908 unsigned mlt
=0, tmp
, err
;
909 /* No concern for performance, it's done once: use a stupid
910 * but safe and compact method to find the multiplier.
913 for (tmp
= 1U<<31; tmp
!= 0; tmp
>>= 1) {
914 if (mulhwu(inscale
, mlt
|tmp
) < outscale
)
918 /* We might still be off by 1 for the best approximation.
919 * A side effect of this is that if outscale is too large
920 * the returned value will be zero.
921 * Many corner cases have been checked and seem to work,
922 * some might have been forgotten in the test however.
925 err
= inscale
* (mlt
+1);
926 if (err
<= inscale
/2)
932 * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
935 void div128_by_32(u64 dividend_high
, u64 dividend_low
,
936 unsigned divisor
, struct div_result
*dr
)
938 unsigned long a
, b
, c
, d
;
939 unsigned long w
, x
, y
, z
;
942 a
= dividend_high
>> 32;
943 b
= dividend_high
& 0xffffffff;
944 c
= dividend_low
>> 32;
945 d
= dividend_low
& 0xffffffff;
948 ra
= ((u64
)(a
- (w
* divisor
)) << 32) + b
;
950 rb
= ((u64
) do_div(ra
, divisor
) << 32) + c
;
953 rc
= ((u64
) do_div(rb
, divisor
) << 32) + d
;
959 dr
->result_high
= ((u64
)w
<< 32) + x
;
960 dr
->result_low
= ((u64
)y
<< 32) + z
;