2 * Copyright 2001 MontaVista Software Inc.
3 * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
4 * Copyright (c) 2003 Maciej W. Rozycki
6 * Common time service routines for MIPS machines. See
7 * Documentation/mips/time.README.
9 * This program is free software; you can redistribute it and/or modify it
10 * under the terms of the GNU General Public License as published by the
11 * Free Software Foundation; either version 2 of the License, or (at your
12 * option) any later version.
14 #include <linux/config.h>
15 #include <linux/types.h>
16 #include <linux/kernel.h>
17 #include <linux/init.h>
18 #include <linux/sched.h>
19 #include <linux/param.h>
20 #include <linux/time.h>
21 #include <linux/timex.h>
22 #include <linux/smp.h>
23 #include <linux/kernel_stat.h>
24 #include <linux/spinlock.h>
25 #include <linux/interrupt.h>
26 #include <linux/module.h>
28 #include <asm/bootinfo.h>
30 #include <asm/cpu-features.h>
31 #include <asm/div64.h>
32 #include <asm/sections.h>
36 * The integer part of the number of usecs per jiffy is taken from tick,
37 * but the fractional part is not recorded, so we calculate it using the
38 * initial value of HZ. This aids systems where tick isn't really an
39 * integer (e.g. for HZ = 128).
41 #define USECS_PER_JIFFY TICK_SIZE
42 #define USECS_PER_JIFFY_FRAC ((unsigned long)(u32)((1000000ULL << 32) / HZ))
44 #define TICK_SIZE (tick_nsec / 1000)
46 u64 jiffies_64 = INITIAL_JIFFIES;
48 EXPORT_SYMBOL(jiffies_64);
53 extern volatile unsigned long wall_jiffies;
55 spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED;
58 * whether we emulate local_timer_interrupts for SMP machines.
60 int emulate_local_timer_interrupt;
64 * By default we provide the null RTC ops
66 static unsigned long null_rtc_get_time(void)
68 return mktime(2000, 1, 1, 0, 0, 0);
71 static int null_rtc_set_time(unsigned long sec)
76 unsigned long (*rtc_get_time)(void) = null_rtc_get_time;
77 int (*rtc_set_time)(unsigned long) = null_rtc_set_time;
78 int (*rtc_set_mmss)(unsigned long);
81 /* usecs per counter cycle, shifted to left by 32 bits */
82 static unsigned int sll32_usecs_per_cycle;
84 /* how many counter cycles in a jiffy */
85 static unsigned long cycles_per_jiffy;
87 /* Cycle counter value at the previous timer interrupt.. */
88 static unsigned int timerhi, timerlo;
90 /* expirelo is the count value for next CPU timer interrupt */
91 static unsigned int expirelo;
95 * Null timer ack for systems not needing one (e.g. i8254).
97 static void null_timer_ack(void) { /* nothing */ }
100 * Null high precision timer functions for systems lacking one.
102 static unsigned int null_hpt_read(void)
107 static void null_hpt_init(unsigned int count) { /* nothing */ }
111 * Timer ack for an R4k-compatible timer of a known frequency.
113 static void c0_timer_ack(void)
117 /* Ack this timer interrupt and set the next one. */
118 expirelo += cycles_per_jiffy;
119 write_c0_compare(expirelo);
121 /* Check to see if we have missed any timer interrupts. */
122 count = read_c0_count();
123 if ((count - expirelo) < 0x7fffffff) {
124 /* missed_timer_count++; */
125 expirelo = count + cycles_per_jiffy;
126 write_c0_compare(expirelo);
131 * High precision timer functions for a R4k-compatible timer.
133 static unsigned int c0_hpt_read(void)
135 return read_c0_count();
138 /* For use solely as a high precision timer. */
139 static void c0_hpt_init(unsigned int count)
141 write_c0_count(read_c0_count() - count);
144 /* For use both as a high precision timer and an interrupt source. */
145 static void c0_hpt_timer_init(unsigned int count)
147 count = read_c0_count() - count;
148 expirelo = (count / cycles_per_jiffy + 1) * cycles_per_jiffy;
149 write_c0_count(expirelo - cycles_per_jiffy);
150 write_c0_compare(expirelo);
151 write_c0_count(count);
154 int (*mips_timer_state)(void);
155 void (*mips_timer_ack)(void);
156 unsigned int (*mips_hpt_read)(void);
157 void (*mips_hpt_init)(unsigned int);
161 * This version of gettimeofday has microsecond resolution and better than
162 * microsecond precision on fast machines with cycle counter.
164 void do_gettimeofday(struct timeval *tv)
168 unsigned long usec, sec;
169 unsigned long max_ntp_tick = tick_usec - tickadj;
172 seq = read_seqbegin(&xtime_lock);
174 usec = do_gettimeoffset();
176 lost = jiffies - wall_jiffies;
179 * If time_adjust is negative then NTP is slowing the clock
180 * so make sure not to go into next possible interval.
181 * Better to lose some accuracy than have time go backwards..
183 if (unlikely(time_adjust < 0)) {
184 usec = min(usec, max_ntp_tick);
187 usec += lost * max_ntp_tick;
188 } else if (unlikely(lost))
189 usec += lost * tick_usec;
192 usec += (xtime.tv_nsec / 1000);
194 } while (read_seqretry(&xtime_lock, seq));
196 while (usec >= 1000000) {
205 EXPORT_SYMBOL(do_gettimeofday);
207 int do_settimeofday(struct timespec *tv)
209 time_t wtm_sec, sec = tv->tv_sec;
210 long wtm_nsec, nsec = tv->tv_nsec;
212 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
215 write_seqlock_irq(&xtime_lock);
218 * This is revolting. We need to set "xtime" correctly. However,
219 * the value in this location is the value at the most recent update
220 * of wall time. Discover what correction gettimeofday() would have
221 * made, and then undo it!
223 nsec -= do_gettimeoffset() * NSEC_PER_USEC;
224 nsec -= (jiffies - wall_jiffies) * tick_nsec;
226 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
227 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
229 set_normalized_timespec(&xtime, sec, nsec);
230 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
232 time_adjust = 0; /* stop active adjtime() */
233 time_status |= STA_UNSYNC;
234 time_maxerror = NTP_PHASE_LIMIT;
235 time_esterror = NTP_PHASE_LIMIT;
237 write_sequnlock_irq(&xtime_lock);
242 EXPORT_SYMBOL(do_settimeofday);
245 * Gettimeoffset routines. These routines returns the time duration
246 * since last timer interrupt in usecs.
248 * If the exact CPU counter frequency is known, use fixed_rate_gettimeoffset.
249 * Otherwise use calibrate_gettimeoffset()
251 * If the CPU does not have the counter register, you can either supply
252 * your own gettimeoffset() routine, or use null_gettimeoffset(), which
253 * gives the same resolution as HZ.
256 static unsigned long null_gettimeoffset(void)
262 /* The function pointer to one of the gettimeoffset funcs. */
263 unsigned long (*do_gettimeoffset)(void) = null_gettimeoffset;
266 static unsigned long fixed_rate_gettimeoffset(void)
271 /* Get last timer tick in absolute kernel time */
272 count = mips_hpt_read();
274 /* .. relative to previous jiffy (32 bits is enough) */
277 __asm__("multu %1,%2"
279 : "r" (count), "r" (sll32_usecs_per_cycle)
283 * Due to possible jiffies inconsistencies, we need to check
284 * the result so that we'll get a timer that is monotonic.
286 if (res >= USECS_PER_JIFFY)
287 res = USECS_PER_JIFFY - 1;
294 * Cached "1/(clocks per usec) * 2^32" value.
295 * It has to be recalculated once each jiffy.
297 static unsigned long cached_quotient;
299 /* Last jiffy when calibrate_divXX_gettimeoffset() was called. */
300 static unsigned long last_jiffies;
303 * This is moved from dec/time.c:do_ioasic_gettimeoffset() by Maciej.
305 static unsigned long calibrate_div32_gettimeoffset(void)
308 unsigned long res, tmp;
309 unsigned long quotient;
313 quotient = cached_quotient;
315 if (last_jiffies != tmp) {
317 if (last_jiffies != 0) {
319 do_div64_32(r0, timerhi, timerlo, tmp);
320 do_div64_32(quotient, USECS_PER_JIFFY,
321 USECS_PER_JIFFY_FRAC, r0);
322 cached_quotient = quotient;
326 /* Get last timer tick in absolute kernel time */
327 count = mips_hpt_read();
329 /* .. relative to previous jiffy (32 bits is enough) */
332 __asm__("multu %1,%2"
334 : "r" (count), "r" (quotient)
338 * Due to possible jiffies inconsistencies, we need to check
339 * the result so that we'll get a timer that is monotonic.
341 if (res >= USECS_PER_JIFFY)
342 res = USECS_PER_JIFFY - 1;
347 static unsigned long calibrate_div64_gettimeoffset(void)
350 unsigned long res, tmp;
351 unsigned long quotient;
355 quotient = cached_quotient;
357 if (last_jiffies != tmp) {
361 __asm__(".set push\n\t"
373 : "=&r" (quotient), "=&r" (r0)
374 : "r" (timerhi), "m" (timerlo),
375 "r" (tmp), "r" (USECS_PER_JIFFY),
376 "r" (USECS_PER_JIFFY_FRAC)
377 : "hi", "lo", "accum");
378 cached_quotient = quotient;
382 /* Get last timer tick in absolute kernel time */
383 count = mips_hpt_read();
385 /* .. relative to previous jiffy (32 bits is enough) */
388 __asm__("multu %1,%2"
390 : "r" (count), "r" (quotient)
394 * Due to possible jiffies inconsistencies, we need to check
395 * the result so that we'll get a timer that is monotonic.
397 if (res >= USECS_PER_JIFFY)
398 res = USECS_PER_JIFFY - 1;
404 /* last time when xtime and rtc are sync'ed up */
405 static long last_rtc_update;
408 * local_timer_interrupt() does profiling and process accounting
409 * on a per-CPU basis.
411 * In UP mode, it is invoked from the (global) timer_interrupt.
413 * In SMP mode, it might invoked by per-CPU timer interrupt, or
414 * a broadcasted inter-processor interrupt which itself is triggered
415 * by the global timer interrupt.
417 void local_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
420 profile_tick(CPU_PROFILING, regs);
422 /* in UP mode, update_process_times() is invoked by do_timer() */
423 update_process_times(user_mode(regs));
428 * High-level timer interrupt service routines. This function
429 * is set as irqaction->handler and is invoked through do_IRQ.
431 irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
436 count = mips_hpt_read();
439 /* Update timerhi/timerlo for intra-jiffy calibration. */
440 timerhi += count < timerlo; /* Wrap around */
444 * call the generic timer interrupt handling
449 * If we have an externally synchronized Linux clock, then update
450 * CMOS clock accordingly every ~11 minutes. rtc_set_time() has to be
451 * called as close as possible to 500 ms before the new second starts.
453 write_seqlock(&xtime_lock);
454 if ((time_status & STA_UNSYNC) == 0 &&
455 xtime.tv_sec > last_rtc_update + 660 &&
456 (xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
457 (xtime.tv_nsec / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2) {
458 if (rtc_set_mmss(xtime.tv_sec) == 0) {
459 last_rtc_update = xtime.tv_sec;
461 /* do it again in 60 s */
462 last_rtc_update = xtime.tv_sec - 600;
465 write_sequnlock(&xtime_lock);
468 * If jiffies has overflown in this timer_interrupt, we must
469 * update the timer[hi]/[lo] to make fast gettimeoffset funcs
470 * quotient calc still valid. -arca
472 * The first timer interrupt comes late as interrupts are
473 * enabled long after timers are initialized. Therefore the
474 * high precision timer is fast, leading to wrong gettimeoffset()
475 * calculations. We deal with it by setting it based on the
476 * number of its ticks between the second and the third interrupt.
477 * That is still somewhat imprecise, but it's a good estimate.
482 static unsigned int prev_count;
483 static int hpt_initialized;
487 timerhi = timerlo = 0;
488 mips_hpt_init(count);
494 if (!hpt_initialized) {
495 unsigned int c3 = 3 * (count - prev_count);
499 mips_hpt_init(count - c3);
508 #if !defined(CONFIG_SMP)
510 * In UP mode, we call local_timer_interrupt() to do profiling
511 * and process accouting.
513 * In SMP mode, local_timer_interrupt() is invoked by appropriate
514 * low-level local timer interrupt handler.
516 local_timer_interrupt(irq, dev_id, regs);
518 #else /* CONFIG_SMP */
520 if (emulate_local_timer_interrupt) {
522 * this is the place where we send out inter-process
523 * interrupts and let each CPU do its own profiling
524 * and process accouting.
526 * Obviously we need to call local_timer_interrupt() for
527 * the current CPU too.
529 panic("Not implemented yet!!!");
531 #endif /* CONFIG_SMP */
536 asmlinkage void ll_timer_interrupt(int irq, struct pt_regs *regs)
539 kstat_this_cpu.irqs[irq]++;
541 /* we keep interrupt disabled all the time */
542 timer_interrupt(irq, NULL, regs);
547 asmlinkage void ll_local_timer_interrupt(int irq, struct pt_regs *regs)
550 if (smp_processor_id() != 0)
551 kstat_this_cpu.irqs[irq]++;
553 /* we keep interrupt disabled all the time */
554 local_timer_interrupt(irq, NULL, regs);
560 * time_init() - it does the following things.
562 * 1) board_time_init() -
563 * a) (optional) set up RTC routines,
564 * b) (optional) calibrate and set the mips_hpt_frequency
565 * (only needed if you intended to use fixed_rate_gettimeoffset
566 * or use cpu counter as timer interrupt source)
567 * 2) setup xtime based on rtc_get_time().
568 * 3) choose a appropriate gettimeoffset routine.
569 * 4) calculate a couple of cached variables for later usage
570 * 5) board_timer_setup() -
571 * a) (optional) over-write any choices made above by time_init().
572 * b) machine specific code should setup the timer irqaction.
573 * c) enable the timer interrupt
576 void (*board_time_init)(void);
577 void (*board_timer_setup)(struct irqaction *irq);
579 unsigned int mips_hpt_frequency;
581 static struct irqaction timer_irqaction = {
582 .handler = timer_interrupt,
583 .flags = SA_INTERRUPT,
587 static unsigned int __init calibrate_hpt(void)
590 u32 hpt_start, hpt_end, hpt_count, hz;
592 const int loops = HZ / 10;
597 * We want to calibrate for 0.1s, but to avoid a 64-bit
598 * division we round the number of loops up to the nearest
601 while (loops > 1 << log_2_loops)
603 i = 1 << log_2_loops;
606 * Wait for a rising edge of the timer interrupt.
608 while (mips_timer_state());
609 while (!mips_timer_state());
612 * Now see how many high precision timer ticks happen
613 * during the calculated number of periods between timer
616 hpt_start = mips_hpt_read();
618 while (mips_timer_state());
619 while (!mips_timer_state());
621 hpt_end = mips_hpt_read();
623 hpt_count = hpt_end - hpt_start;
625 frequency = (u64)hpt_count * (u64)hz;
627 return frequency >> log_2_loops;
630 void __init time_init(void)
636 rtc_set_mmss = rtc_set_time;
638 xtime.tv_sec = rtc_get_time();
641 set_normalized_timespec(&wall_to_monotonic,
642 -xtime.tv_sec, -xtime.tv_nsec);
644 /* Choose appropriate high precision timer routines. */
645 if (!cpu_has_counter && !mips_hpt_read) {
646 /* No high precision timer -- sorry. */
647 mips_hpt_read = null_hpt_read;
648 mips_hpt_init = null_hpt_init;
649 } else if (!mips_hpt_frequency && !mips_timer_state) {
650 /* A high precision timer of unknown frequency. */
651 if (!mips_hpt_read) {
652 /* No external high precision timer -- use R4k. */
653 mips_hpt_read = c0_hpt_read;
654 mips_hpt_init = c0_hpt_init;
657 if ((current_cpu_data.isa_level == MIPS_CPU_ISA_M32) ||
658 (current_cpu_data.isa_level == MIPS_CPU_ISA_I) ||
659 (current_cpu_data.isa_level == MIPS_CPU_ISA_II))
661 * We need to calibrate the counter but we don't have
664 do_gettimeoffset = calibrate_div32_gettimeoffset;
667 * We need to calibrate the counter but we *do* have
670 do_gettimeoffset = calibrate_div64_gettimeoffset;
672 /* We know counter frequency. Or we can get it. */
673 if (!mips_hpt_read) {
674 /* No external high precision timer -- use R4k. */
675 mips_hpt_read = c0_hpt_read;
677 if (mips_timer_state)
678 mips_hpt_init = c0_hpt_init;
680 /* No external timer interrupt -- use R4k. */
681 mips_hpt_init = c0_hpt_timer_init;
682 mips_timer_ack = c0_timer_ack;
685 if (!mips_hpt_frequency)
686 mips_hpt_frequency = calibrate_hpt();
688 do_gettimeoffset = fixed_rate_gettimeoffset;
690 /* Calculate cache parameters. */
691 cycles_per_jiffy = (mips_hpt_frequency + HZ / 2) / HZ;
693 /* sll32_usecs_per_cycle = 10^6 * 2^32 / mips_counter_freq */
694 do_div64_32(sll32_usecs_per_cycle,
695 1000000, mips_hpt_frequency / 2,
698 /* Report the high precision timer rate for a reference. */
699 printk("Using %u.%03u MHz high precision timer.\n",
700 ((mips_hpt_frequency + 500) / 1000) / 1000,
701 ((mips_hpt_frequency + 500) / 1000) % 1000);
705 /* No timer interrupt ack (e.g. i8254). */
706 mips_timer_ack = null_timer_ack;
708 /* This sets up the high precision timer for the first interrupt. */
709 mips_hpt_init(mips_hpt_read());
712 * Call board specific timer interrupt setup.
714 * this pointer must be setup in machine setup routine.
716 * Even if a machine chooses to use a low-level timer interrupt,
717 * it still needs to setup the timer_irqaction.
718 * In that case, it might be better to set timer_irqaction.handler
719 * to be NULL function so that we are sure the high-level code
720 * is not invoked accidentally.
722 board_timer_setup(&timer_irqaction);
726 #define STARTOFTIME 1970
727 #define SECDAY 86400L
728 #define SECYR (SECDAY * 365)
729 #define leapyear(y) ((!((y) % 4) && ((y) % 100)) || !((y) % 400))
730 #define days_in_year(y) (leapyear(y) ? 366 : 365)
731 #define days_in_month(m) (month_days[(m) - 1])
733 static int month_days[12] = {
734 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
737 void to_tm(unsigned long tim, struct rtc_time *tm)
742 gday = day = tim / SECDAY;
745 /* Hours, minutes, seconds are easy */
746 tm->tm_hour = hms / 3600;
747 tm->tm_min = (hms % 3600) / 60;
748 tm->tm_sec = (hms % 3600) % 60;
750 /* Number of years in days */
751 for (i = STARTOFTIME; day >= days_in_year(i); i++)
752 day -= days_in_year(i);
755 /* Number of months in days left */
756 if (leapyear(tm->tm_year))
757 days_in_month(FEBRUARY) = 29;
758 for (i = 1; day >= days_in_month(i); i++)
759 day -= days_in_month(i);
760 days_in_month(FEBRUARY) = 28;
761 tm->tm_mon = i - 1; /* tm_mon starts from 0 to 11 */
763 /* Days are what is left over (+1) from all that. */
764 tm->tm_mday = day + 1;
767 * Determine the day of week
769 tm->tm_wday = (gday + 4) % 7; /* 1970/1/1 was Thursday */
772 EXPORT_SYMBOL(rtc_lock);
773 EXPORT_SYMBOL(to_tm);
774 EXPORT_SYMBOL(rtc_set_time);
775 EXPORT_SYMBOL(rtc_get_time);
777 unsigned long long sched_clock(void)
779 return (unsigned long long)jiffies*(1000000000/HZ);