2 * Copyright 2001 MontaVista Software Inc.
3 * Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
4 * Copyright (c) 2003, 2004 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>
29 #include <asm/compiler.h>
31 #include <asm/cpu-features.h>
32 #include <asm/div64.h>
33 #include <asm/sections.h>
37 * The integer part of the number of usecs per jiffy is taken from tick,
38 * but the fractional part is not recorded, so we calculate it using the
39 * initial value of HZ. This aids systems where tick isn't really an
40 * integer (e.g. for HZ = 128).
42 #define USECS_PER_JIFFY TICK_SIZE
43 #define USECS_PER_JIFFY_FRAC ((unsigned long)(u32)((1000000ULL << 32) / HZ))
45 #define TICK_SIZE (tick_nsec / 1000)
47 u64 jiffies_64 = INITIAL_JIFFIES;
49 EXPORT_SYMBOL(jiffies_64);
54 extern volatile unsigned long wall_jiffies;
56 spinlock_t rtc_lock = SPIN_LOCK_UNLOCKED;
59 * By default we provide the null RTC ops
61 static unsigned long null_rtc_get_time(void)
63 return mktime(2000, 1, 1, 0, 0, 0);
66 static int null_rtc_set_time(unsigned long sec)
71 unsigned long (*rtc_get_time)(void) = null_rtc_get_time;
72 int (*rtc_set_time)(unsigned long) = null_rtc_set_time;
73 int (*rtc_set_mmss)(unsigned long);
76 /* usecs per counter cycle, shifted to left by 32 bits */
77 static unsigned int sll32_usecs_per_cycle;
79 /* how many counter cycles in a jiffy */
80 static unsigned long cycles_per_jiffy;
82 /* Cycle counter value at the previous timer interrupt.. */
83 static unsigned int timerhi, timerlo;
85 /* expirelo is the count value for next CPU timer interrupt */
86 static unsigned int expirelo;
90 * Null timer ack for systems not needing one (e.g. i8254).
92 static void null_timer_ack(void) { /* nothing */ }
95 * Null high precision timer functions for systems lacking one.
97 static unsigned int null_hpt_read(void)
102 static void null_hpt_init(unsigned int count) { /* nothing */ }
106 * Timer ack for an R4k-compatible timer of a known frequency.
108 static void c0_timer_ack(void)
112 /* Ack this timer interrupt and set the next one. */
113 expirelo += cycles_per_jiffy;
114 write_c0_compare(expirelo);
116 /* Check to see if we have missed any timer interrupts. */
117 count = read_c0_count();
118 if ((count - expirelo) < 0x7fffffff) {
119 /* missed_timer_count++; */
120 expirelo = count + cycles_per_jiffy;
121 write_c0_compare(expirelo);
126 * High precision timer functions for a R4k-compatible timer.
128 static unsigned int c0_hpt_read(void)
130 return read_c0_count();
133 /* For use solely as a high precision timer. */
134 static void c0_hpt_init(unsigned int count)
136 write_c0_count(read_c0_count() - count);
139 /* For use both as a high precision timer and an interrupt source. */
140 static void c0_hpt_timer_init(unsigned int count)
142 count = read_c0_count() - count;
143 expirelo = (count / cycles_per_jiffy + 1) * cycles_per_jiffy;
144 write_c0_count(expirelo - cycles_per_jiffy);
145 write_c0_compare(expirelo);
146 write_c0_count(count);
149 int (*mips_timer_state)(void);
150 void (*mips_timer_ack)(void);
151 unsigned int (*mips_hpt_read)(void);
152 void (*mips_hpt_init)(unsigned int);
156 * This version of gettimeofday has microsecond resolution and better than
157 * microsecond precision on fast machines with cycle counter.
159 void do_gettimeofday(struct timeval *tv)
163 unsigned long usec, sec;
164 unsigned long max_ntp_tick = tick_usec - tickadj;
167 seq = read_seqbegin(&xtime_lock);
169 usec = do_gettimeoffset();
171 lost = jiffies - wall_jiffies;
174 * If time_adjust is negative then NTP is slowing the clock
175 * so make sure not to go into next possible interval.
176 * Better to lose some accuracy than have time go backwards..
178 if (unlikely(time_adjust < 0)) {
179 usec = min(usec, max_ntp_tick);
182 usec += lost * max_ntp_tick;
183 } else if (unlikely(lost))
184 usec += lost * tick_usec;
187 usec += (xtime.tv_nsec / 1000);
189 } while (read_seqretry(&xtime_lock, seq));
191 while (usec >= 1000000) {
200 EXPORT_SYMBOL(do_gettimeofday);
202 int do_settimeofday(struct timespec *tv)
204 time_t wtm_sec, sec = tv->tv_sec;
205 long wtm_nsec, nsec = tv->tv_nsec;
207 if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
210 write_seqlock_irq(&xtime_lock);
213 * This is revolting. We need to set "xtime" correctly. However,
214 * the value in this location is the value at the most recent update
215 * of wall time. Discover what correction gettimeofday() would have
216 * made, and then undo it!
218 nsec -= do_gettimeoffset() * NSEC_PER_USEC;
219 nsec -= (jiffies - wall_jiffies) * tick_nsec;
221 wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
222 wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
224 set_normalized_timespec(&xtime, sec, nsec);
225 set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
227 time_adjust = 0; /* stop active adjtime() */
228 time_status |= STA_UNSYNC;
229 time_maxerror = NTP_PHASE_LIMIT;
230 time_esterror = NTP_PHASE_LIMIT;
232 write_sequnlock_irq(&xtime_lock);
237 EXPORT_SYMBOL(do_settimeofday);
240 * Gettimeoffset routines. These routines returns the time duration
241 * since last timer interrupt in usecs.
243 * If the exact CPU counter frequency is known, use fixed_rate_gettimeoffset.
244 * Otherwise use calibrate_gettimeoffset()
246 * If the CPU does not have the counter register, you can either supply
247 * your own gettimeoffset() routine, or use null_gettimeoffset(), which
248 * gives the same resolution as HZ.
251 static unsigned long null_gettimeoffset(void)
257 /* The function pointer to one of the gettimeoffset funcs. */
258 unsigned long (*do_gettimeoffset)(void) = null_gettimeoffset;
261 static unsigned long fixed_rate_gettimeoffset(void)
266 /* Get last timer tick in absolute kernel time */
267 count = mips_hpt_read();
269 /* .. relative to previous jiffy (32 bits is enough) */
272 __asm__("multu %1,%2"
274 : "r" (count), "r" (sll32_usecs_per_cycle)
275 : "lo", GCC_REG_ACCUM);
278 * Due to possible jiffies inconsistencies, we need to check
279 * the result so that we'll get a timer that is monotonic.
281 if (res >= USECS_PER_JIFFY)
282 res = USECS_PER_JIFFY - 1;
289 * Cached "1/(clocks per usec) * 2^32" value.
290 * It has to be recalculated once each jiffy.
292 static unsigned long cached_quotient;
294 /* Last jiffy when calibrate_divXX_gettimeoffset() was called. */
295 static unsigned long last_jiffies;
298 * This is moved from dec/time.c:do_ioasic_gettimeoffset() by Maciej.
300 static unsigned long calibrate_div32_gettimeoffset(void)
303 unsigned long res, tmp;
304 unsigned long quotient;
308 quotient = cached_quotient;
310 if (last_jiffies != tmp) {
312 if (last_jiffies != 0) {
314 do_div64_32(r0, timerhi, timerlo, tmp);
315 do_div64_32(quotient, USECS_PER_JIFFY,
316 USECS_PER_JIFFY_FRAC, r0);
317 cached_quotient = quotient;
321 /* Get last timer tick in absolute kernel time */
322 count = mips_hpt_read();
324 /* .. relative to previous jiffy (32 bits is enough) */
327 __asm__("multu %1,%2"
329 : "r" (count), "r" (quotient)
330 : "lo", GCC_REG_ACCUM);
333 * Due to possible jiffies inconsistencies, we need to check
334 * the result so that we'll get a timer that is monotonic.
336 if (res >= USECS_PER_JIFFY)
337 res = USECS_PER_JIFFY - 1;
342 static unsigned long calibrate_div64_gettimeoffset(void)
345 unsigned long res, tmp;
346 unsigned long quotient;
350 quotient = cached_quotient;
352 if (last_jiffies != tmp) {
356 __asm__(".set push\n\t"
368 : "=&r" (quotient), "=&r" (r0)
369 : "r" (timerhi), "m" (timerlo),
370 "r" (tmp), "r" (USECS_PER_JIFFY),
371 "r" (USECS_PER_JIFFY_FRAC)
372 : "hi", "lo", GCC_REG_ACCUM);
373 cached_quotient = quotient;
377 /* Get last timer tick in absolute kernel time */
378 count = mips_hpt_read();
380 /* .. relative to previous jiffy (32 bits is enough) */
383 __asm__("multu %1,%2"
385 : "r" (count), "r" (quotient)
386 : "lo", GCC_REG_ACCUM);
389 * Due to possible jiffies inconsistencies, we need to check
390 * the result so that we'll get a timer that is monotonic.
392 if (res >= USECS_PER_JIFFY)
393 res = USECS_PER_JIFFY - 1;
399 /* last time when xtime and rtc are sync'ed up */
400 static long last_rtc_update;
403 * local_timer_interrupt() does profiling and process accounting
404 * on a per-CPU basis.
406 * In UP mode, it is invoked from the (global) timer_interrupt.
408 * In SMP mode, it might invoked by per-CPU timer interrupt, or
409 * a broadcasted inter-processor interrupt which itself is triggered
410 * by the global timer interrupt.
412 void local_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
415 profile_tick(CPU_PROFILING, regs);
416 update_process_times(user_mode(regs));
420 * High-level timer interrupt service routines. This function
421 * is set as irqaction->handler and is invoked through do_IRQ.
423 irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
428 count = mips_hpt_read();
431 /* Update timerhi/timerlo for intra-jiffy calibration. */
432 timerhi += count < timerlo; /* Wrap around */
436 * call the generic timer interrupt handling
441 * If we have an externally synchronized Linux clock, then update
442 * CMOS clock accordingly every ~11 minutes. rtc_set_time() has to be
443 * called as close as possible to 500 ms before the new second starts.
445 write_seqlock(&xtime_lock);
446 if ((time_status & STA_UNSYNC) == 0 &&
447 xtime.tv_sec > last_rtc_update + 660 &&
448 (xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
449 (xtime.tv_nsec / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2) {
450 if (rtc_set_mmss(xtime.tv_sec) == 0) {
451 last_rtc_update = xtime.tv_sec;
453 /* do it again in 60 s */
454 last_rtc_update = xtime.tv_sec - 600;
457 write_sequnlock(&xtime_lock);
460 * If jiffies has overflown in this timer_interrupt, we must
461 * update the timer[hi]/[lo] to make fast gettimeoffset funcs
462 * quotient calc still valid. -arca
464 * The first timer interrupt comes late as interrupts are
465 * enabled long after timers are initialized. Therefore the
466 * high precision timer is fast, leading to wrong gettimeoffset()
467 * calculations. We deal with it by setting it based on the
468 * number of its ticks between the second and the third interrupt.
469 * That is still somewhat imprecise, but it's a good estimate.
474 static unsigned int prev_count;
475 static int hpt_initialized;
479 timerhi = timerlo = 0;
480 mips_hpt_init(count);
486 if (!hpt_initialized) {
487 unsigned int c3 = 3 * (count - prev_count);
491 mips_hpt_init(count - c3);
501 * In UP mode, we call local_timer_interrupt() to do profiling
502 * and process accouting.
504 * In SMP mode, local_timer_interrupt() is invoked by appropriate
505 * low-level local timer interrupt handler.
507 local_timer_interrupt(irq, dev_id, regs);
512 asmlinkage void ll_timer_interrupt(int irq, struct pt_regs *regs)
515 kstat_this_cpu.irqs[irq]++;
517 /* we keep interrupt disabled all the time */
518 timer_interrupt(irq, NULL, regs);
523 asmlinkage void ll_local_timer_interrupt(int irq, struct pt_regs *regs)
526 if (smp_processor_id() != 0)
527 kstat_this_cpu.irqs[irq]++;
529 /* we keep interrupt disabled all the time */
530 local_timer_interrupt(irq, NULL, regs);
536 * time_init() - it does the following things.
538 * 1) board_time_init() -
539 * a) (optional) set up RTC routines,
540 * b) (optional) calibrate and set the mips_hpt_frequency
541 * (only needed if you intended to use fixed_rate_gettimeoffset
542 * or use cpu counter as timer interrupt source)
543 * 2) setup xtime based on rtc_get_time().
544 * 3) choose a appropriate gettimeoffset routine.
545 * 4) calculate a couple of cached variables for later usage
546 * 5) board_timer_setup() -
547 * a) (optional) over-write any choices made above by time_init().
548 * b) machine specific code should setup the timer irqaction.
549 * c) enable the timer interrupt
552 void (*board_time_init)(void);
553 void (*board_timer_setup)(struct irqaction *irq);
555 unsigned int mips_hpt_frequency;
557 static struct irqaction timer_irqaction = {
558 .handler = timer_interrupt,
559 .flags = SA_INTERRUPT,
563 static unsigned int __init calibrate_hpt(void)
566 u32 hpt_start, hpt_end, hpt_count, hz;
568 const int loops = HZ / 10;
573 * We want to calibrate for 0.1s, but to avoid a 64-bit
574 * division we round the number of loops up to the nearest
577 while (loops > 1 << log_2_loops)
579 i = 1 << log_2_loops;
582 * Wait for a rising edge of the timer interrupt.
584 while (mips_timer_state());
585 while (!mips_timer_state());
588 * Now see how many high precision timer ticks happen
589 * during the calculated number of periods between timer
592 hpt_start = mips_hpt_read();
594 while (mips_timer_state());
595 while (!mips_timer_state());
597 hpt_end = mips_hpt_read();
599 hpt_count = hpt_end - hpt_start;
601 frequency = (u64)hpt_count * (u64)hz;
603 return frequency >> log_2_loops;
606 void __init time_init(void)
612 rtc_set_mmss = rtc_set_time;
614 xtime.tv_sec = rtc_get_time();
617 set_normalized_timespec(&wall_to_monotonic,
618 -xtime.tv_sec, -xtime.tv_nsec);
620 /* Choose appropriate high precision timer routines. */
621 if (!cpu_has_counter && !mips_hpt_read) {
622 /* No high precision timer -- sorry. */
623 mips_hpt_read = null_hpt_read;
624 mips_hpt_init = null_hpt_init;
625 } else if (!mips_hpt_frequency && !mips_timer_state) {
626 /* A high precision timer of unknown frequency. */
627 if (!mips_hpt_read) {
628 /* No external high precision timer -- use R4k. */
629 mips_hpt_read = c0_hpt_read;
630 mips_hpt_init = c0_hpt_init;
633 if ((current_cpu_data.isa_level == MIPS_CPU_ISA_M32) ||
634 (current_cpu_data.isa_level == MIPS_CPU_ISA_I) ||
635 (current_cpu_data.isa_level == MIPS_CPU_ISA_II))
637 * We need to calibrate the counter but we don't have
640 do_gettimeoffset = calibrate_div32_gettimeoffset;
643 * We need to calibrate the counter but we *do* have
646 do_gettimeoffset = calibrate_div64_gettimeoffset;
648 /* We know counter frequency. Or we can get it. */
649 if (!mips_hpt_read) {
650 /* No external high precision timer -- use R4k. */
651 mips_hpt_read = c0_hpt_read;
653 if (mips_timer_state)
654 mips_hpt_init = c0_hpt_init;
656 /* No external timer interrupt -- use R4k. */
657 mips_hpt_init = c0_hpt_timer_init;
658 mips_timer_ack = c0_timer_ack;
661 if (!mips_hpt_frequency)
662 mips_hpt_frequency = calibrate_hpt();
664 do_gettimeoffset = fixed_rate_gettimeoffset;
666 /* Calculate cache parameters. */
667 cycles_per_jiffy = (mips_hpt_frequency + HZ / 2) / HZ;
669 /* sll32_usecs_per_cycle = 10^6 * 2^32 / mips_counter_freq */
670 do_div64_32(sll32_usecs_per_cycle,
671 1000000, mips_hpt_frequency / 2,
674 /* Report the high precision timer rate for a reference. */
675 printk("Using %u.%03u MHz high precision timer.\n",
676 ((mips_hpt_frequency + 500) / 1000) / 1000,
677 ((mips_hpt_frequency + 500) / 1000) % 1000);
681 /* No timer interrupt ack (e.g. i8254). */
682 mips_timer_ack = null_timer_ack;
684 /* This sets up the high precision timer for the first interrupt. */
685 mips_hpt_init(mips_hpt_read());
688 * Call board specific timer interrupt setup.
690 * this pointer must be setup in machine setup routine.
692 * Even if a machine chooses to use a low-level timer interrupt,
693 * it still needs to setup the timer_irqaction.
694 * In that case, it might be better to set timer_irqaction.handler
695 * to be NULL function so that we are sure the high-level code
696 * is not invoked accidentally.
698 board_timer_setup(&timer_irqaction);
702 #define STARTOFTIME 1970
703 #define SECDAY 86400L
704 #define SECYR (SECDAY * 365)
705 #define leapyear(y) ((!((y) % 4) && ((y) % 100)) || !((y) % 400))
706 #define days_in_year(y) (leapyear(y) ? 366 : 365)
707 #define days_in_month(m) (month_days[(m) - 1])
709 static int month_days[12] = {
710 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
713 void to_tm(unsigned long tim, struct rtc_time *tm)
718 gday = day = tim / SECDAY;
721 /* Hours, minutes, seconds are easy */
722 tm->tm_hour = hms / 3600;
723 tm->tm_min = (hms % 3600) / 60;
724 tm->tm_sec = (hms % 3600) % 60;
726 /* Number of years in days */
727 for (i = STARTOFTIME; day >= days_in_year(i); i++)
728 day -= days_in_year(i);
731 /* Number of months in days left */
732 if (leapyear(tm->tm_year))
733 days_in_month(FEBRUARY) = 29;
734 for (i = 1; day >= days_in_month(i); i++)
735 day -= days_in_month(i);
736 days_in_month(FEBRUARY) = 28;
737 tm->tm_mon = i - 1; /* tm_mon starts from 0 to 11 */
739 /* Days are what is left over (+1) from all that. */
740 tm->tm_mday = day + 1;
743 * Determine the day of week
745 tm->tm_wday = (gday + 4) % 7; /* 1970/1/1 was Thursday */
748 EXPORT_SYMBOL(rtc_lock);
749 EXPORT_SYMBOL(to_tm);
750 EXPORT_SYMBOL(rtc_set_time);
751 EXPORT_SYMBOL(rtc_get_time);
753 unsigned long long sched_clock(void)
755 return (unsigned long long)jiffies*(1000000000/HZ);