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-rw-r--r--arch/ppc64/kernel/time.c881
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diff --git a/arch/ppc64/kernel/time.c b/arch/ppc64/kernel/time.c
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1/*
2 *
3 * Common time routines among all ppc machines.
4 *
5 * Written by Cort Dougan (cort@cs.nmt.edu) to merge
6 * Paul Mackerras' version and mine for PReP and Pmac.
7 * MPC8xx/MBX changes by Dan Malek (dmalek@jlc.net).
8 * Converted for 64-bit by Mike Corrigan (mikejc@us.ibm.com)
9 *
10 * First round of bugfixes by Gabriel Paubert (paubert@iram.es)
11 * to make clock more stable (2.4.0-test5). The only thing
12 * that this code assumes is that the timebases have been synchronized
13 * by firmware on SMP and are never stopped (never do sleep
14 * on SMP then, nap and doze are OK).
15 *
16 * Speeded up do_gettimeofday by getting rid of references to
17 * xtime (which required locks for consistency). (mikejc@us.ibm.com)
18 *
19 * TODO (not necessarily in this file):
20 * - improve precision and reproducibility of timebase frequency
21 * measurement at boot time. (for iSeries, we calibrate the timebase
22 * against the Titan chip's clock.)
23 * - for astronomical applications: add a new function to get
24 * non ambiguous timestamps even around leap seconds. This needs
25 * a new timestamp format and a good name.
26 *
27 * 1997-09-10 Updated NTP code according to technical memorandum Jan '96
28 * "A Kernel Model for Precision Timekeeping" by Dave Mills
29 *
30 * This program is free software; you can redistribute it and/or
31 * modify it under the terms of the GNU General Public License
32 * as published by the Free Software Foundation; either version
33 * 2 of the License, or (at your option) any later version.
34 */
35
36#include <linux/config.h>
37#include <linux/errno.h>
38#include <linux/module.h>
39#include <linux/sched.h>
40#include <linux/kernel.h>
41#include <linux/param.h>
42#include <linux/string.h>
43#include <linux/mm.h>
44#include <linux/interrupt.h>
45#include <linux/timex.h>
46#include <linux/kernel_stat.h>
47#include <linux/mc146818rtc.h>
48#include <linux/time.h>
49#include <linux/init.h>
50#include <linux/profile.h>
51#include <linux/cpu.h>
52#include <linux/security.h>
53
54#include <asm/io.h>
55#include <asm/processor.h>
56#include <asm/nvram.h>
57#include <asm/cache.h>
58#include <asm/machdep.h>
59#ifdef CONFIG_PPC_ISERIES
60#include <asm/iSeries/ItLpQueue.h>
61#include <asm/iSeries/HvCallXm.h>
62#endif
63#include <asm/uaccess.h>
64#include <asm/time.h>
65#include <asm/ppcdebug.h>
66#include <asm/prom.h>
67#include <asm/sections.h>
68#include <asm/systemcfg.h>
69#include <asm/firmware.h>
70
71u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
72
73EXPORT_SYMBOL(jiffies_64);
74
75/* keep track of when we need to update the rtc */
76time_t last_rtc_update;
77extern int piranha_simulator;
78#ifdef CONFIG_PPC_ISERIES
79unsigned long iSeries_recal_titan = 0;
80unsigned long iSeries_recal_tb = 0;
81static unsigned long first_settimeofday = 1;
82#endif
83
84#define XSEC_PER_SEC (1024*1024)
85
86unsigned long tb_ticks_per_jiffy;
87unsigned long tb_ticks_per_usec = 100; /* sane default */
88EXPORT_SYMBOL(tb_ticks_per_usec);
89unsigned long tb_ticks_per_sec;
90unsigned long tb_to_xs;
91unsigned tb_to_us;
92unsigned long processor_freq;
93DEFINE_SPINLOCK(rtc_lock);
94EXPORT_SYMBOL_GPL(rtc_lock);
95
96unsigned long tb_to_ns_scale;
97unsigned long tb_to_ns_shift;
98
99struct gettimeofday_struct do_gtod;
100
101extern unsigned long wall_jiffies;
102extern int smp_tb_synchronized;
103
104extern struct timezone sys_tz;
105
106void ppc_adjtimex(void);
107
108static unsigned adjusting_time = 0;
109
110unsigned long ppc_proc_freq;
111unsigned long ppc_tb_freq;
112
113static __inline__ void timer_check_rtc(void)
114{
115 /*
116 * update the rtc when needed, this should be performed on the
117 * right fraction of a second. Half or full second ?
118 * Full second works on mk48t59 clocks, others need testing.
119 * Note that this update is basically only used through
120 * the adjtimex system calls. Setting the HW clock in
121 * any other way is a /dev/rtc and userland business.
122 * This is still wrong by -0.5/+1.5 jiffies because of the
123 * timer interrupt resolution and possible delay, but here we
124 * hit a quantization limit which can only be solved by higher
125 * resolution timers and decoupling time management from timer
126 * interrupts. This is also wrong on the clocks
127 * which require being written at the half second boundary.
128 * We should have an rtc call that only sets the minutes and
129 * seconds like on Intel to avoid problems with non UTC clocks.
130 */
131 if (ntp_synced() &&
132 xtime.tv_sec - last_rtc_update >= 659 &&
133 abs((xtime.tv_nsec/1000) - (1000000-1000000/HZ)) < 500000/HZ &&
134 jiffies - wall_jiffies == 1) {
135 struct rtc_time tm;
136 to_tm(xtime.tv_sec+1, &tm);
137 tm.tm_year -= 1900;
138 tm.tm_mon -= 1;
139 if (ppc_md.set_rtc_time(&tm) == 0)
140 last_rtc_update = xtime.tv_sec+1;
141 else
142 /* Try again one minute later */
143 last_rtc_update += 60;
144 }
145}
146
147/*
148 * This version of gettimeofday has microsecond resolution.
149 */
150static inline void __do_gettimeofday(struct timeval *tv, unsigned long tb_val)
151{
152 unsigned long sec, usec, tb_ticks;
153 unsigned long xsec, tb_xsec;
154 struct gettimeofday_vars * temp_varp;
155 unsigned long temp_tb_to_xs, temp_stamp_xsec;
156
157 /*
158 * These calculations are faster (gets rid of divides)
159 * if done in units of 1/2^20 rather than microseconds.
160 * The conversion to microseconds at the end is done
161 * without a divide (and in fact, without a multiply)
162 */
163 temp_varp = do_gtod.varp;
164 tb_ticks = tb_val - temp_varp->tb_orig_stamp;
165 temp_tb_to_xs = temp_varp->tb_to_xs;
166 temp_stamp_xsec = temp_varp->stamp_xsec;
167 tb_xsec = mulhdu( tb_ticks, temp_tb_to_xs );
168 xsec = temp_stamp_xsec + tb_xsec;
169 sec = xsec / XSEC_PER_SEC;
170 xsec -= sec * XSEC_PER_SEC;
171 usec = (xsec * USEC_PER_SEC)/XSEC_PER_SEC;
172
173 tv->tv_sec = sec;
174 tv->tv_usec = usec;
175}
176
177void do_gettimeofday(struct timeval *tv)
178{
179 __do_gettimeofday(tv, get_tb());
180}
181
182EXPORT_SYMBOL(do_gettimeofday);
183
184/* Synchronize xtime with do_gettimeofday */
185
186static inline void timer_sync_xtime(unsigned long cur_tb)
187{
188 struct timeval my_tv;
189
190 __do_gettimeofday(&my_tv, cur_tb);
191
192 if (xtime.tv_sec <= my_tv.tv_sec) {
193 xtime.tv_sec = my_tv.tv_sec;
194 xtime.tv_nsec = my_tv.tv_usec * 1000;
195 }
196}
197
198/*
199 * When the timebase - tb_orig_stamp gets too big, we do a manipulation
200 * between tb_orig_stamp and stamp_xsec. The goal here is to keep the
201 * difference tb - tb_orig_stamp small enough to always fit inside a
202 * 32 bits number. This is a requirement of our fast 32 bits userland
203 * implementation in the vdso. If we "miss" a call to this function
204 * (interrupt latency, CPU locked in a spinlock, ...) and we end up
205 * with a too big difference, then the vdso will fallback to calling
206 * the syscall
207 */
208static __inline__ void timer_recalc_offset(unsigned long cur_tb)
209{
210 struct gettimeofday_vars * temp_varp;
211 unsigned temp_idx;
212 unsigned long offset, new_stamp_xsec, new_tb_orig_stamp;
213
214 if (((cur_tb - do_gtod.varp->tb_orig_stamp) & 0x80000000u) == 0)
215 return;
216
217 temp_idx = (do_gtod.var_idx == 0);
218 temp_varp = &do_gtod.vars[temp_idx];
219
220 new_tb_orig_stamp = cur_tb;
221 offset = new_tb_orig_stamp - do_gtod.varp->tb_orig_stamp;
222 new_stamp_xsec = do_gtod.varp->stamp_xsec + mulhdu(offset, do_gtod.varp->tb_to_xs);
223
224 temp_varp->tb_to_xs = do_gtod.varp->tb_to_xs;
225 temp_varp->tb_orig_stamp = new_tb_orig_stamp;
226 temp_varp->stamp_xsec = new_stamp_xsec;
227 smp_mb();
228 do_gtod.varp = temp_varp;
229 do_gtod.var_idx = temp_idx;
230
231 ++(systemcfg->tb_update_count);
232 smp_wmb();
233 systemcfg->tb_orig_stamp = new_tb_orig_stamp;
234 systemcfg->stamp_xsec = new_stamp_xsec;
235 smp_wmb();
236 ++(systemcfg->tb_update_count);
237}
238
239#ifdef CONFIG_SMP
240unsigned long profile_pc(struct pt_regs *regs)
241{
242 unsigned long pc = instruction_pointer(regs);
243
244 if (in_lock_functions(pc))
245 return regs->link;
246
247 return pc;
248}
249EXPORT_SYMBOL(profile_pc);
250#endif
251
252#ifdef CONFIG_PPC_ISERIES
253
254/*
255 * This function recalibrates the timebase based on the 49-bit time-of-day
256 * value in the Titan chip. The Titan is much more accurate than the value
257 * returned by the service processor for the timebase frequency.
258 */
259
260static void iSeries_tb_recal(void)
261{
262 struct div_result divres;
263 unsigned long titan, tb;
264 tb = get_tb();
265 titan = HvCallXm_loadTod();
266 if ( iSeries_recal_titan ) {
267 unsigned long tb_ticks = tb - iSeries_recal_tb;
268 unsigned long titan_usec = (titan - iSeries_recal_titan) >> 12;
269 unsigned long new_tb_ticks_per_sec = (tb_ticks * USEC_PER_SEC)/titan_usec;
270 unsigned long new_tb_ticks_per_jiffy = (new_tb_ticks_per_sec+(HZ/2))/HZ;
271 long tick_diff = new_tb_ticks_per_jiffy - tb_ticks_per_jiffy;
272 char sign = '+';
273 /* make sure tb_ticks_per_sec and tb_ticks_per_jiffy are consistent */
274 new_tb_ticks_per_sec = new_tb_ticks_per_jiffy * HZ;
275
276 if ( tick_diff < 0 ) {
277 tick_diff = -tick_diff;
278 sign = '-';
279 }
280 if ( tick_diff ) {
281 if ( tick_diff < tb_ticks_per_jiffy/25 ) {
282 printk( "Titan recalibrate: new tb_ticks_per_jiffy = %lu (%c%ld)\n",
283 new_tb_ticks_per_jiffy, sign, tick_diff );
284 tb_ticks_per_jiffy = new_tb_ticks_per_jiffy;
285 tb_ticks_per_sec = new_tb_ticks_per_sec;
286 div128_by_32( XSEC_PER_SEC, 0, tb_ticks_per_sec, &divres );
287 do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
288 tb_to_xs = divres.result_low;
289 do_gtod.varp->tb_to_xs = tb_to_xs;
290 systemcfg->tb_ticks_per_sec = tb_ticks_per_sec;
291 systemcfg->tb_to_xs = tb_to_xs;
292 }
293 else {
294 printk( "Titan recalibrate: FAILED (difference > 4 percent)\n"
295 " new tb_ticks_per_jiffy = %lu\n"
296 " old tb_ticks_per_jiffy = %lu\n",
297 new_tb_ticks_per_jiffy, tb_ticks_per_jiffy );
298 }
299 }
300 }
301 iSeries_recal_titan = titan;
302 iSeries_recal_tb = tb;
303}
304#endif
305
306/*
307 * For iSeries shared processors, we have to let the hypervisor
308 * set the hardware decrementer. We set a virtual decrementer
309 * in the lppaca and call the hypervisor if the virtual
310 * decrementer is less than the current value in the hardware
311 * decrementer. (almost always the new decrementer value will
312 * be greater than the current hardware decementer so the hypervisor
313 * call will not be needed)
314 */
315
316unsigned long tb_last_stamp __cacheline_aligned_in_smp;
317
318/*
319 * timer_interrupt - gets called when the decrementer overflows,
320 * with interrupts disabled.
321 */
322int timer_interrupt(struct pt_regs * regs)
323{
324 int next_dec;
325 unsigned long cur_tb;
326 struct paca_struct *lpaca = get_paca();
327 unsigned long cpu = smp_processor_id();
328
329 irq_enter();
330
331 profile_tick(CPU_PROFILING, regs);
332
333 lpaca->lppaca.int_dword.fields.decr_int = 0;
334
335 while (lpaca->next_jiffy_update_tb <= (cur_tb = get_tb())) {
336 /*
337 * We cannot disable the decrementer, so in the period
338 * between this cpu's being marked offline in cpu_online_map
339 * and calling stop-self, it is taking timer interrupts.
340 * Avoid calling into the scheduler rebalancing code if this
341 * is the case.
342 */
343 if (!cpu_is_offline(cpu))
344 update_process_times(user_mode(regs));
345 /*
346 * No need to check whether cpu is offline here; boot_cpuid
347 * should have been fixed up by now.
348 */
349 if (cpu == boot_cpuid) {
350 write_seqlock(&xtime_lock);
351 tb_last_stamp = lpaca->next_jiffy_update_tb;
352 timer_recalc_offset(lpaca->next_jiffy_update_tb);
353 do_timer(regs);
354 timer_sync_xtime(lpaca->next_jiffy_update_tb);
355 timer_check_rtc();
356 write_sequnlock(&xtime_lock);
357 if ( adjusting_time && (time_adjust == 0) )
358 ppc_adjtimex();
359 }
360 lpaca->next_jiffy_update_tb += tb_ticks_per_jiffy;
361 }
362
363 next_dec = lpaca->next_jiffy_update_tb - cur_tb;
364 if (next_dec > lpaca->default_decr)
365 next_dec = lpaca->default_decr;
366 set_dec(next_dec);
367
368#ifdef CONFIG_PPC_ISERIES
369 if (hvlpevent_is_pending())
370 process_hvlpevents(regs);
371#endif
372
373 /* collect purr register values often, for accurate calculations */
374 if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
375 struct cpu_usage *cu = &__get_cpu_var(cpu_usage_array);
376 cu->current_tb = mfspr(SPRN_PURR);
377 }
378
379 irq_exit();
380
381 return 1;
382}
383
384/*
385 * Scheduler clock - returns current time in nanosec units.
386 *
387 * Note: mulhdu(a, b) (multiply high double unsigned) returns
388 * the high 64 bits of a * b, i.e. (a * b) >> 64, where a and b
389 * are 64-bit unsigned numbers.
390 */
391unsigned long long sched_clock(void)
392{
393 return mulhdu(get_tb(), tb_to_ns_scale) << tb_to_ns_shift;
394}
395
396int do_settimeofday(struct timespec *tv)
397{
398 time_t wtm_sec, new_sec = tv->tv_sec;
399 long wtm_nsec, new_nsec = tv->tv_nsec;
400 unsigned long flags;
401 unsigned long delta_xsec;
402 long int tb_delta;
403 unsigned long new_xsec;
404
405 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
406 return -EINVAL;
407
408 write_seqlock_irqsave(&xtime_lock, flags);
409 /* Updating the RTC is not the job of this code. If the time is
410 * stepped under NTP, the RTC will be update after STA_UNSYNC
411 * is cleared. Tool like clock/hwclock either copy the RTC
412 * to the system time, in which case there is no point in writing
413 * to the RTC again, or write to the RTC but then they don't call
414 * settimeofday to perform this operation.
415 */
416#ifdef CONFIG_PPC_ISERIES
417 if ( first_settimeofday ) {
418 iSeries_tb_recal();
419 first_settimeofday = 0;
420 }
421#endif
422 tb_delta = tb_ticks_since(tb_last_stamp);
423 tb_delta += (jiffies - wall_jiffies) * tb_ticks_per_jiffy;
424
425 new_nsec -= tb_delta / tb_ticks_per_usec / 1000;
426
427 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - new_sec);
428 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - new_nsec);
429
430 set_normalized_timespec(&xtime, new_sec, new_nsec);
431 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
432
433 /* In case of a large backwards jump in time with NTP, we want the
434 * clock to be updated as soon as the PLL is again in lock.
435 */
436 last_rtc_update = new_sec - 658;
437
438 ntp_clear();
439
440 delta_xsec = mulhdu( (tb_last_stamp-do_gtod.varp->tb_orig_stamp),
441 do_gtod.varp->tb_to_xs );
442
443 new_xsec = (new_nsec * XSEC_PER_SEC) / NSEC_PER_SEC;
444 new_xsec += new_sec * XSEC_PER_SEC;
445 if ( new_xsec > delta_xsec ) {
446 do_gtod.varp->stamp_xsec = new_xsec - delta_xsec;
447 systemcfg->stamp_xsec = new_xsec - delta_xsec;
448 }
449 else {
450 /* This is only for the case where the user is setting the time
451 * way back to a time such that the boot time would have been
452 * before 1970 ... eg. we booted ten days ago, and we are setting
453 * the time to Jan 5, 1970 */
454 do_gtod.varp->stamp_xsec = new_xsec;
455 do_gtod.varp->tb_orig_stamp = tb_last_stamp;
456 systemcfg->stamp_xsec = new_xsec;
457 systemcfg->tb_orig_stamp = tb_last_stamp;
458 }
459
460 systemcfg->tz_minuteswest = sys_tz.tz_minuteswest;
461 systemcfg->tz_dsttime = sys_tz.tz_dsttime;
462
463 write_sequnlock_irqrestore(&xtime_lock, flags);
464 clock_was_set();
465 return 0;
466}
467
468EXPORT_SYMBOL(do_settimeofday);
469
470#if defined(CONFIG_PPC_PSERIES) || defined(CONFIG_PPC_MAPLE) || defined(CONFIG_PPC_BPA)
471void __init generic_calibrate_decr(void)
472{
473 struct device_node *cpu;
474 struct div_result divres;
475 unsigned int *fp;
476 int node_found;
477
478 /*
479 * The cpu node should have a timebase-frequency property
480 * to tell us the rate at which the decrementer counts.
481 */
482 cpu = of_find_node_by_type(NULL, "cpu");
483
484 ppc_tb_freq = DEFAULT_TB_FREQ; /* hardcoded default */
485 node_found = 0;
486 if (cpu != 0) {
487 fp = (unsigned int *)get_property(cpu, "timebase-frequency",
488 NULL);
489 if (fp != 0) {
490 node_found = 1;
491 ppc_tb_freq = *fp;
492 }
493 }
494 if (!node_found)
495 printk(KERN_ERR "WARNING: Estimating decrementer frequency "
496 "(not found)\n");
497
498 ppc_proc_freq = DEFAULT_PROC_FREQ;
499 node_found = 0;
500 if (cpu != 0) {
501 fp = (unsigned int *)get_property(cpu, "clock-frequency",
502 NULL);
503 if (fp != 0) {
504 node_found = 1;
505 ppc_proc_freq = *fp;
506 }
507 }
508 if (!node_found)
509 printk(KERN_ERR "WARNING: Estimating processor frequency "
510 "(not found)\n");
511
512 of_node_put(cpu);
513
514 printk(KERN_INFO "time_init: decrementer frequency = %lu.%.6lu MHz\n",
515 ppc_tb_freq/1000000, ppc_tb_freq%1000000);
516 printk(KERN_INFO "time_init: processor frequency = %lu.%.6lu MHz\n",
517 ppc_proc_freq/1000000, ppc_proc_freq%1000000);
518
519 tb_ticks_per_jiffy = ppc_tb_freq / HZ;
520 tb_ticks_per_sec = tb_ticks_per_jiffy * HZ;
521 tb_ticks_per_usec = ppc_tb_freq / 1000000;
522 tb_to_us = mulhwu_scale_factor(ppc_tb_freq, 1000000);
523 div128_by_32(1024*1024, 0, tb_ticks_per_sec, &divres);
524 tb_to_xs = divres.result_low;
525
526 setup_default_decr();
527}
528#endif
529
530void __init time_init(void)
531{
532 /* This function is only called on the boot processor */
533 unsigned long flags;
534 struct rtc_time tm;
535 struct div_result res;
536 unsigned long scale, shift;
537
538 ppc_md.calibrate_decr();
539
540 /*
541 * Compute scale factor for sched_clock.
542 * The calibrate_decr() function has set tb_ticks_per_sec,
543 * which is the timebase frequency.
544 * We compute 1e9 * 2^64 / tb_ticks_per_sec and interpret
545 * the 128-bit result as a 64.64 fixed-point number.
546 * We then shift that number right until it is less than 1.0,
547 * giving us the scale factor and shift count to use in
548 * sched_clock().
549 */
550 div128_by_32(1000000000, 0, tb_ticks_per_sec, &res);
551 scale = res.result_low;
552 for (shift = 0; res.result_high != 0; ++shift) {
553 scale = (scale >> 1) | (res.result_high << 63);
554 res.result_high >>= 1;
555 }
556 tb_to_ns_scale = scale;
557 tb_to_ns_shift = shift;
558
559#ifdef CONFIG_PPC_ISERIES
560 if (!piranha_simulator)
561#endif
562 ppc_md.get_boot_time(&tm);
563
564 write_seqlock_irqsave(&xtime_lock, flags);
565 xtime.tv_sec = mktime(tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
566 tm.tm_hour, tm.tm_min, tm.tm_sec);
567 tb_last_stamp = get_tb();
568 do_gtod.varp = &do_gtod.vars[0];
569 do_gtod.var_idx = 0;
570 do_gtod.varp->tb_orig_stamp = tb_last_stamp;
571 get_paca()->next_jiffy_update_tb = tb_last_stamp + tb_ticks_per_jiffy;
572 do_gtod.varp->stamp_xsec = xtime.tv_sec * XSEC_PER_SEC;
573 do_gtod.tb_ticks_per_sec = tb_ticks_per_sec;
574 do_gtod.varp->tb_to_xs = tb_to_xs;
575 do_gtod.tb_to_us = tb_to_us;
576 systemcfg->tb_orig_stamp = tb_last_stamp;
577 systemcfg->tb_update_count = 0;
578 systemcfg->tb_ticks_per_sec = tb_ticks_per_sec;
579 systemcfg->stamp_xsec = xtime.tv_sec * XSEC_PER_SEC;
580 systemcfg->tb_to_xs = tb_to_xs;
581
582 time_freq = 0;
583
584 xtime.tv_nsec = 0;
585 last_rtc_update = xtime.tv_sec;
586 set_normalized_timespec(&wall_to_monotonic,
587 -xtime.tv_sec, -xtime.tv_nsec);
588 write_sequnlock_irqrestore(&xtime_lock, flags);
589
590 /* Not exact, but the timer interrupt takes care of this */
591 set_dec(tb_ticks_per_jiffy);
592}
593
594/*
595 * After adjtimex is called, adjust the conversion of tb ticks
596 * to microseconds to keep do_gettimeofday synchronized
597 * with ntpd.
598 *
599 * Use the time_adjust, time_freq and time_offset computed by adjtimex to
600 * adjust the frequency.
601 */
602
603/* #define DEBUG_PPC_ADJTIMEX 1 */
604
605void ppc_adjtimex(void)
606{
607 unsigned long den, new_tb_ticks_per_sec, tb_ticks, old_xsec, new_tb_to_xs, new_xsec, new_stamp_xsec;
608 unsigned long tb_ticks_per_sec_delta;
609 long delta_freq, ltemp;
610 struct div_result divres;
611 unsigned long flags;
612 struct gettimeofday_vars * temp_varp;
613 unsigned temp_idx;
614 long singleshot_ppm = 0;
615
616 /* Compute parts per million frequency adjustment to accomplish the time adjustment
617 implied by time_offset to be applied over the elapsed time indicated by time_constant.
618 Use SHIFT_USEC to get it into the same units as time_freq. */
619 if ( time_offset < 0 ) {
620 ltemp = -time_offset;
621 ltemp <<= SHIFT_USEC - SHIFT_UPDATE;
622 ltemp >>= SHIFT_KG + time_constant;
623 ltemp = -ltemp;
624 }
625 else {
626 ltemp = time_offset;
627 ltemp <<= SHIFT_USEC - SHIFT_UPDATE;
628 ltemp >>= SHIFT_KG + time_constant;
629 }
630
631 /* If there is a single shot time adjustment in progress */
632 if ( time_adjust ) {
633#ifdef DEBUG_PPC_ADJTIMEX
634 printk("ppc_adjtimex: ");
635 if ( adjusting_time == 0 )
636 printk("starting ");
637 printk("single shot time_adjust = %ld\n", time_adjust);
638#endif
639
640 adjusting_time = 1;
641
642 /* Compute parts per million frequency adjustment to match time_adjust */
643 singleshot_ppm = tickadj * HZ;
644 /*
645 * The adjustment should be tickadj*HZ to match the code in
646 * linux/kernel/timer.c, but experiments show that this is too
647 * large. 3/4 of tickadj*HZ seems about right
648 */
649 singleshot_ppm -= singleshot_ppm / 4;
650 /* Use SHIFT_USEC to get it into the same units as time_freq */
651 singleshot_ppm <<= SHIFT_USEC;
652 if ( time_adjust < 0 )
653 singleshot_ppm = -singleshot_ppm;
654 }
655 else {
656#ifdef DEBUG_PPC_ADJTIMEX
657 if ( adjusting_time )
658 printk("ppc_adjtimex: ending single shot time_adjust\n");
659#endif
660 adjusting_time = 0;
661 }
662
663 /* Add up all of the frequency adjustments */
664 delta_freq = time_freq + ltemp + singleshot_ppm;
665
666 /* Compute a new value for tb_ticks_per_sec based on the frequency adjustment */
667 den = 1000000 * (1 << (SHIFT_USEC - 8));
668 if ( delta_freq < 0 ) {
669 tb_ticks_per_sec_delta = ( tb_ticks_per_sec * ( (-delta_freq) >> (SHIFT_USEC - 8))) / den;
670 new_tb_ticks_per_sec = tb_ticks_per_sec + tb_ticks_per_sec_delta;
671 }
672 else {
673 tb_ticks_per_sec_delta = ( tb_ticks_per_sec * ( delta_freq >> (SHIFT_USEC - 8))) / den;
674 new_tb_ticks_per_sec = tb_ticks_per_sec - tb_ticks_per_sec_delta;
675 }
676
677#ifdef DEBUG_PPC_ADJTIMEX
678 printk("ppc_adjtimex: ltemp = %ld, time_freq = %ld, singleshot_ppm = %ld\n", ltemp, time_freq, singleshot_ppm);
679 printk("ppc_adjtimex: tb_ticks_per_sec - base = %ld new = %ld\n", tb_ticks_per_sec, new_tb_ticks_per_sec);
680#endif
681
682 /* Compute a new value of tb_to_xs (used to convert tb to microseconds and a new value of
683 stamp_xsec which is the time (in 1/2^20 second units) corresponding to tb_orig_stamp. This
684 new value of stamp_xsec compensates for the change in frequency (implied by the new tb_to_xs)
685 which guarantees that the current time remains the same */
686 write_seqlock_irqsave( &xtime_lock, flags );
687 tb_ticks = get_tb() - do_gtod.varp->tb_orig_stamp;
688 div128_by_32( 1024*1024, 0, new_tb_ticks_per_sec, &divres );
689 new_tb_to_xs = divres.result_low;
690 new_xsec = mulhdu( tb_ticks, new_tb_to_xs );
691
692 old_xsec = mulhdu( tb_ticks, do_gtod.varp->tb_to_xs );
693 new_stamp_xsec = do_gtod.varp->stamp_xsec + old_xsec - new_xsec;
694
695 /* There are two copies of tb_to_xs and stamp_xsec so that no lock is needed to access and use these
696 values in do_gettimeofday. We alternate the copies and as long as a reasonable time elapses between
697 changes, there will never be inconsistent values. ntpd has a minimum of one minute between updates */
698
699 temp_idx = (do_gtod.var_idx == 0);
700 temp_varp = &do_gtod.vars[temp_idx];
701
702 temp_varp->tb_to_xs = new_tb_to_xs;
703 temp_varp->stamp_xsec = new_stamp_xsec;
704 temp_varp->tb_orig_stamp = do_gtod.varp->tb_orig_stamp;
705 smp_mb();
706 do_gtod.varp = temp_varp;
707 do_gtod.var_idx = temp_idx;
708
709 /*
710 * tb_update_count is used to allow the problem state gettimeofday code
711 * to assure itself that it sees a consistent view of the tb_to_xs and
712 * stamp_xsec variables. It reads the tb_update_count, then reads
713 * tb_to_xs and stamp_xsec and then reads tb_update_count again. If
714 * the two values of tb_update_count match and are even then the
715 * tb_to_xs and stamp_xsec values are consistent. If not, then it
716 * loops back and reads them again until this criteria is met.
717 */
718 ++(systemcfg->tb_update_count);
719 smp_wmb();
720 systemcfg->tb_to_xs = new_tb_to_xs;
721 systemcfg->stamp_xsec = new_stamp_xsec;
722 smp_wmb();
723 ++(systemcfg->tb_update_count);
724
725 write_sequnlock_irqrestore( &xtime_lock, flags );
726
727}
728
729
730#define TICK_SIZE tick
731#define FEBRUARY 2
732#define STARTOFTIME 1970
733#define SECDAY 86400L
734#define SECYR (SECDAY * 365)
735#define leapyear(year) ((year) % 4 == 0)
736#define days_in_year(a) (leapyear(a) ? 366 : 365)
737#define days_in_month(a) (month_days[(a) - 1])
738
739static int month_days[12] = {
740 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
741};
742
743/*
744 * This only works for the Gregorian calendar - i.e. after 1752 (in the UK)
745 */
746void GregorianDay(struct rtc_time * tm)
747{
748 int leapsToDate;
749 int lastYear;
750 int day;
751 int MonthOffset[] = { 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334 };
752
753 lastYear=tm->tm_year-1;
754
755 /*
756 * Number of leap corrections to apply up to end of last year
757 */
758 leapsToDate = lastYear/4 - lastYear/100 + lastYear/400;
759
760 /*
761 * This year is a leap year if it is divisible by 4 except when it is
762 * divisible by 100 unless it is divisible by 400
763 *
764 * e.g. 1904 was a leap year, 1900 was not, 1996 is, and 2000 will be
765 */
766 if((tm->tm_year%4==0) &&
767 ((tm->tm_year%100!=0) || (tm->tm_year%400==0)) &&
768 (tm->tm_mon>2))
769 {
770 /*
771 * We are past Feb. 29 in a leap year
772 */
773 day=1;
774 }
775 else
776 {
777 day=0;
778 }
779
780 day += lastYear*365 + leapsToDate + MonthOffset[tm->tm_mon-1] +
781 tm->tm_mday;
782
783 tm->tm_wday=day%7;
784}
785
786void to_tm(int tim, struct rtc_time * tm)
787{
788 register int i;
789 register long hms, day;
790
791 day = tim / SECDAY;
792 hms = tim % SECDAY;
793
794 /* Hours, minutes, seconds are easy */
795 tm->tm_hour = hms / 3600;
796 tm->tm_min = (hms % 3600) / 60;
797 tm->tm_sec = (hms % 3600) % 60;
798
799 /* Number of years in days */
800 for (i = STARTOFTIME; day >= days_in_year(i); i++)
801 day -= days_in_year(i);
802 tm->tm_year = i;
803
804 /* Number of months in days left */
805 if (leapyear(tm->tm_year))
806 days_in_month(FEBRUARY) = 29;
807 for (i = 1; day >= days_in_month(i); i++)
808 day -= days_in_month(i);
809 days_in_month(FEBRUARY) = 28;
810 tm->tm_mon = i;
811
812 /* Days are what is left over (+1) from all that. */
813 tm->tm_mday = day + 1;
814
815 /*
816 * Determine the day of week
817 */
818 GregorianDay(tm);
819}
820
821/* Auxiliary function to compute scaling factors */
822/* Actually the choice of a timebase running at 1/4 the of the bus
823 * frequency giving resolution of a few tens of nanoseconds is quite nice.
824 * It makes this computation very precise (27-28 bits typically) which
825 * is optimistic considering the stability of most processor clock
826 * oscillators and the precision with which the timebase frequency
827 * is measured but does not harm.
828 */
829unsigned mulhwu_scale_factor(unsigned inscale, unsigned outscale) {
830 unsigned mlt=0, tmp, err;
831 /* No concern for performance, it's done once: use a stupid
832 * but safe and compact method to find the multiplier.
833 */
834
835 for (tmp = 1U<<31; tmp != 0; tmp >>= 1) {
836 if (mulhwu(inscale, mlt|tmp) < outscale) mlt|=tmp;
837 }
838
839 /* We might still be off by 1 for the best approximation.
840 * A side effect of this is that if outscale is too large
841 * the returned value will be zero.
842 * Many corner cases have been checked and seem to work,
843 * some might have been forgotten in the test however.
844 */
845
846 err = inscale*(mlt+1);
847 if (err <= inscale/2) mlt++;
848 return mlt;
849 }
850
851/*
852 * Divide a 128-bit dividend by a 32-bit divisor, leaving a 128 bit
853 * result.
854 */
855
856void div128_by_32( unsigned long dividend_high, unsigned long dividend_low,
857 unsigned divisor, struct div_result *dr )
858{
859 unsigned long a,b,c,d, w,x,y,z, ra,rb,rc;
860
861 a = dividend_high >> 32;
862 b = dividend_high & 0xffffffff;
863 c = dividend_low >> 32;
864 d = dividend_low & 0xffffffff;
865
866 w = a/divisor;
867 ra = (a - (w * divisor)) << 32;
868
869 x = (ra + b)/divisor;
870 rb = ((ra + b) - (x * divisor)) << 32;
871
872 y = (rb + c)/divisor;
873 rc = ((rb + c) - (y * divisor)) << 32;
874
875 z = (rc + d)/divisor;
876
877 dr->result_high = (w << 32) + x;
878 dr->result_low = (y << 32) + z;
879
880}
881
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