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/types.h>
15 #include <linux/kernel.h>
16 #include <linux/init.h>
17 #include <linux/sched.h>
18 #include <linux/param.h>
19 #include <linux/time.h>
20 #include <linux/timex.h>
21 #include <linux/smp.h>
22 #include <linux/kernel_stat.h>
23 #include <linux/spinlock.h>
24 #include <linux/interrupt.h>
25 #include <linux/module.h>
27 #include <asm/bootinfo.h>
28 #include <asm/compiler.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 DEFINE_SPINLOCK(rtc_lock
);
58 * By default we provide the null RTC ops
60 static unsigned long null_rtc_get_time(void)
62 return mktime(2000, 1, 1, 0, 0, 0);
65 static int null_rtc_set_time(unsigned long sec
)
70 unsigned long (*rtc_get_time
)(void) = null_rtc_get_time
;
71 int (*rtc_set_time
)(unsigned long) = null_rtc_set_time
;
72 int (*rtc_set_mmss
)(unsigned long);
75 /* usecs per counter cycle, shifted to left by 32 bits */
76 static unsigned int sll32_usecs_per_cycle
;
78 /* how many counter cycles in a jiffy */
79 static unsigned long cycles_per_jiffy
;
81 /* Cycle counter value at the previous timer interrupt.. */
82 static unsigned int timerhi
, timerlo
;
84 /* expirelo is the count value for next CPU timer interrupt */
85 static unsigned int expirelo
;
89 * Null timer ack for systems not needing one (e.g. i8254).
91 static void null_timer_ack(void) { /* nothing */ }
94 * Null high precision timer functions for systems lacking one.
96 static unsigned int null_hpt_read(void)
101 static void null_hpt_init(unsigned int count
) { /* nothing */ }
105 * Timer ack for an R4k-compatible timer of a known frequency.
107 static void c0_timer_ack(void)
111 /* Ack this timer interrupt and set the next one. */
112 expirelo
+= cycles_per_jiffy
;
113 write_c0_compare(expirelo
);
115 /* Check to see if we have missed any timer interrupts. */
116 count
= read_c0_count();
117 if ((count
- expirelo
) < 0x7fffffff) {
118 /* missed_timer_count++; */
119 expirelo
= count
+ cycles_per_jiffy
;
120 write_c0_compare(expirelo
);
125 * High precision timer functions for a R4k-compatible timer.
127 static unsigned int c0_hpt_read(void)
129 return read_c0_count();
132 /* For use solely as a high precision timer. */
133 static void c0_hpt_init(unsigned int count
)
135 write_c0_count(read_c0_count() - count
);
138 /* For use both as a high precision timer and an interrupt source. */
139 static void c0_hpt_timer_init(unsigned int count
)
141 count
= read_c0_count() - count
;
142 expirelo
= (count
/ cycles_per_jiffy
+ 1) * cycles_per_jiffy
;
143 write_c0_count(expirelo
- cycles_per_jiffy
);
144 write_c0_compare(expirelo
);
145 write_c0_count(count
);
148 int (*mips_timer_state
)(void);
149 void (*mips_timer_ack
)(void);
150 unsigned int (*mips_hpt_read
)(void);
151 void (*mips_hpt_init
)(unsigned int);
155 * This version of gettimeofday has microsecond resolution and better than
156 * microsecond precision on fast machines with cycle counter.
158 void do_gettimeofday(struct timeval
*tv
)
162 unsigned long usec
, sec
;
163 unsigned long max_ntp_tick
= tick_usec
- tickadj
;
166 seq
= read_seqbegin(&xtime_lock
);
168 usec
= do_gettimeoffset();
170 lost
= jiffies
- wall_jiffies
;
173 * If time_adjust is negative then NTP is slowing the clock
174 * so make sure not to go into next possible interval.
175 * Better to lose some accuracy than have time go backwards..
177 if (unlikely(time_adjust
< 0)) {
178 usec
= min(usec
, max_ntp_tick
);
181 usec
+= lost
* max_ntp_tick
;
182 } else if (unlikely(lost
))
183 usec
+= lost
* tick_usec
;
186 usec
+= (xtime
.tv_nsec
/ 1000);
188 } while (read_seqretry(&xtime_lock
, seq
));
190 while (usec
>= 1000000) {
199 EXPORT_SYMBOL(do_gettimeofday
);
201 int do_settimeofday(struct timespec
*tv
)
203 time_t wtm_sec
, sec
= tv
->tv_sec
;
204 long wtm_nsec
, nsec
= tv
->tv_nsec
;
206 if ((unsigned long)tv
->tv_nsec
>= NSEC_PER_SEC
)
209 write_seqlock_irq(&xtime_lock
);
212 * This is revolting. We need to set "xtime" correctly. However,
213 * the value in this location is the value at the most recent update
214 * of wall time. Discover what correction gettimeofday() would have
215 * made, and then undo it!
217 nsec
-= do_gettimeoffset() * NSEC_PER_USEC
;
218 nsec
-= (jiffies
- wall_jiffies
) * tick_nsec
;
220 wtm_sec
= wall_to_monotonic
.tv_sec
+ (xtime
.tv_sec
- sec
);
221 wtm_nsec
= wall_to_monotonic
.tv_nsec
+ (xtime
.tv_nsec
- nsec
);
223 set_normalized_timespec(&xtime
, sec
, nsec
);
224 set_normalized_timespec(&wall_to_monotonic
, wtm_sec
, wtm_nsec
);
228 write_sequnlock_irq(&xtime_lock
);
233 EXPORT_SYMBOL(do_settimeofday
);
236 * Gettimeoffset routines. These routines returns the time duration
237 * since last timer interrupt in usecs.
239 * If the exact CPU counter frequency is known, use fixed_rate_gettimeoffset.
240 * Otherwise use calibrate_gettimeoffset()
242 * If the CPU does not have the counter register, you can either supply
243 * your own gettimeoffset() routine, or use null_gettimeoffset(), which
244 * gives the same resolution as HZ.
247 static unsigned long null_gettimeoffset(void)
253 /* The function pointer to one of the gettimeoffset funcs. */
254 unsigned long (*do_gettimeoffset
)(void) = null_gettimeoffset
;
257 static unsigned long fixed_rate_gettimeoffset(void)
262 /* Get last timer tick in absolute kernel time */
263 count
= mips_hpt_read();
265 /* .. relative to previous jiffy (32 bits is enough) */
268 __asm__("multu %1,%2"
270 : "r" (count
), "r" (sll32_usecs_per_cycle
)
271 : "lo", GCC_REG_ACCUM
);
274 * Due to possible jiffies inconsistencies, we need to check
275 * the result so that we'll get a timer that is monotonic.
277 if (res
>= USECS_PER_JIFFY
)
278 res
= USECS_PER_JIFFY
- 1;
285 * Cached "1/(clocks per usec) * 2^32" value.
286 * It has to be recalculated once each jiffy.
288 static unsigned long cached_quotient
;
290 /* Last jiffy when calibrate_divXX_gettimeoffset() was called. */
291 static unsigned long last_jiffies
;
294 * This is moved from dec/time.c:do_ioasic_gettimeoffset() by Maciej.
296 static unsigned long calibrate_div32_gettimeoffset(void)
299 unsigned long res
, tmp
;
300 unsigned long quotient
;
304 quotient
= cached_quotient
;
306 if (last_jiffies
!= tmp
) {
308 if (last_jiffies
!= 0) {
310 do_div64_32(r0
, timerhi
, timerlo
, tmp
);
311 do_div64_32(quotient
, USECS_PER_JIFFY
,
312 USECS_PER_JIFFY_FRAC
, r0
);
313 cached_quotient
= quotient
;
317 /* Get last timer tick in absolute kernel time */
318 count
= mips_hpt_read();
320 /* .. relative to previous jiffy (32 bits is enough) */
323 __asm__("multu %1,%2"
325 : "r" (count
), "r" (quotient
)
326 : "lo", GCC_REG_ACCUM
);
329 * Due to possible jiffies inconsistencies, we need to check
330 * the result so that we'll get a timer that is monotonic.
332 if (res
>= USECS_PER_JIFFY
)
333 res
= USECS_PER_JIFFY
- 1;
338 static unsigned long calibrate_div64_gettimeoffset(void)
341 unsigned long res
, tmp
;
342 unsigned long quotient
;
346 quotient
= cached_quotient
;
348 if (last_jiffies
!= tmp
) {
352 __asm__(".set push\n\t"
364 : "=&r" (quotient
), "=&r" (r0
)
365 : "r" (timerhi
), "m" (timerlo
),
366 "r" (tmp
), "r" (USECS_PER_JIFFY
),
367 "r" (USECS_PER_JIFFY_FRAC
)
368 : "hi", "lo", GCC_REG_ACCUM
);
369 cached_quotient
= quotient
;
373 /* Get last timer tick in absolute kernel time */
374 count
= mips_hpt_read();
376 /* .. relative to previous jiffy (32 bits is enough) */
379 __asm__("multu %1,%2"
381 : "r" (count
), "r" (quotient
)
382 : "lo", GCC_REG_ACCUM
);
385 * Due to possible jiffies inconsistencies, we need to check
386 * the result so that we'll get a timer that is monotonic.
388 if (res
>= USECS_PER_JIFFY
)
389 res
= USECS_PER_JIFFY
- 1;
395 /* last time when xtime and rtc are sync'ed up */
396 static long last_rtc_update
;
399 * local_timer_interrupt() does profiling and process accounting
400 * on a per-CPU basis.
402 * In UP mode, it is invoked from the (global) timer_interrupt.
404 * In SMP mode, it might invoked by per-CPU timer interrupt, or
405 * a broadcasted inter-processor interrupt which itself is triggered
406 * by the global timer interrupt.
408 void local_timer_interrupt(int irq
, void *dev_id
, struct pt_regs
*regs
)
411 profile_tick(CPU_PROFILING
, regs
);
412 update_process_times(user_mode(regs
));
416 * High-level timer interrupt service routines. This function
417 * is set as irqaction->handler and is invoked through do_IRQ.
419 irqreturn_t
timer_interrupt(int irq
, void *dev_id
, struct pt_regs
*regs
)
424 count
= mips_hpt_read();
427 /* Update timerhi/timerlo for intra-jiffy calibration. */
428 timerhi
+= count
< timerlo
; /* Wrap around */
432 * call the generic timer interrupt handling
437 * If we have an externally synchronized Linux clock, then update
438 * CMOS clock accordingly every ~11 minutes. rtc_set_time() has to be
439 * called as close as possible to 500 ms before the new second starts.
441 write_seqlock(&xtime_lock
);
443 xtime
.tv_sec
> last_rtc_update
+ 660 &&
444 (xtime
.tv_nsec
/ 1000) >= 500000 - ((unsigned) TICK_SIZE
) / 2 &&
445 (xtime
.tv_nsec
/ 1000) <= 500000 + ((unsigned) TICK_SIZE
) / 2) {
446 if (rtc_set_mmss(xtime
.tv_sec
) == 0) {
447 last_rtc_update
= xtime
.tv_sec
;
449 /* do it again in 60 s */
450 last_rtc_update
= xtime
.tv_sec
- 600;
453 write_sequnlock(&xtime_lock
);
456 * If jiffies has overflown in this timer_interrupt, we must
457 * update the timer[hi]/[lo] to make fast gettimeoffset funcs
458 * quotient calc still valid. -arca
460 * The first timer interrupt comes late as interrupts are
461 * enabled long after timers are initialized. Therefore the
462 * high precision timer is fast, leading to wrong gettimeoffset()
463 * calculations. We deal with it by setting it based on the
464 * number of its ticks between the second and the third interrupt.
465 * That is still somewhat imprecise, but it's a good estimate.
470 static unsigned int prev_count
;
471 static int hpt_initialized
;
475 timerhi
= timerlo
= 0;
476 mips_hpt_init(count
);
482 if (!hpt_initialized
) {
483 unsigned int c3
= 3 * (count
- prev_count
);
487 mips_hpt_init(count
- c3
);
497 * In UP mode, we call local_timer_interrupt() to do profiling
498 * and process accouting.
500 * In SMP mode, local_timer_interrupt() is invoked by appropriate
501 * low-level local timer interrupt handler.
503 local_timer_interrupt(irq
, dev_id
, regs
);
508 asmlinkage
void ll_timer_interrupt(int irq
, struct pt_regs
*regs
)
511 kstat_this_cpu
.irqs
[irq
]++;
513 /* we keep interrupt disabled all the time */
514 timer_interrupt(irq
, NULL
, regs
);
519 asmlinkage
void ll_local_timer_interrupt(int irq
, struct pt_regs
*regs
)
522 if (smp_processor_id() != 0)
523 kstat_this_cpu
.irqs
[irq
]++;
525 /* we keep interrupt disabled all the time */
526 local_timer_interrupt(irq
, NULL
, regs
);
532 * time_init() - it does the following things.
534 * 1) board_time_init() -
535 * a) (optional) set up RTC routines,
536 * b) (optional) calibrate and set the mips_hpt_frequency
537 * (only needed if you intended to use fixed_rate_gettimeoffset
538 * or use cpu counter as timer interrupt source)
539 * 2) setup xtime based on rtc_get_time().
540 * 3) choose a appropriate gettimeoffset routine.
541 * 4) calculate a couple of cached variables for later usage
542 * 5) board_timer_setup() -
543 * a) (optional) over-write any choices made above by time_init().
544 * b) machine specific code should setup the timer irqaction.
545 * c) enable the timer interrupt
548 void (*board_time_init
)(void);
549 void (*board_timer_setup
)(struct irqaction
*irq
);
551 unsigned int mips_hpt_frequency
;
553 static struct irqaction timer_irqaction
= {
554 .handler
= timer_interrupt
,
555 .flags
= SA_INTERRUPT
,
559 static unsigned int __init
calibrate_hpt(void)
562 u32 hpt_start
, hpt_end
, hpt_count
, hz
;
564 const int loops
= HZ
/ 10;
569 * We want to calibrate for 0.1s, but to avoid a 64-bit
570 * division we round the number of loops up to the nearest
573 while (loops
> 1 << log_2_loops
)
575 i
= 1 << log_2_loops
;
578 * Wait for a rising edge of the timer interrupt.
580 while (mips_timer_state());
581 while (!mips_timer_state());
584 * Now see how many high precision timer ticks happen
585 * during the calculated number of periods between timer
588 hpt_start
= mips_hpt_read();
590 while (mips_timer_state());
591 while (!mips_timer_state());
593 hpt_end
= mips_hpt_read();
595 hpt_count
= hpt_end
- hpt_start
;
597 frequency
= (u64
)hpt_count
* (u64
)hz
;
599 return frequency
>> log_2_loops
;
602 void __init
time_init(void)
608 rtc_set_mmss
= rtc_set_time
;
610 xtime
.tv_sec
= rtc_get_time();
613 set_normalized_timespec(&wall_to_monotonic
,
614 -xtime
.tv_sec
, -xtime
.tv_nsec
);
616 /* Choose appropriate high precision timer routines. */
617 if (!cpu_has_counter
&& !mips_hpt_read
) {
618 /* No high precision timer -- sorry. */
619 mips_hpt_read
= null_hpt_read
;
620 mips_hpt_init
= null_hpt_init
;
621 } else if (!mips_hpt_frequency
&& !mips_timer_state
) {
622 /* A high precision timer of unknown frequency. */
623 if (!mips_hpt_read
) {
624 /* No external high precision timer -- use R4k. */
625 mips_hpt_read
= c0_hpt_read
;
626 mips_hpt_init
= c0_hpt_init
;
629 if ((current_cpu_data
.isa_level
== MIPS_CPU_ISA_M32
) ||
630 (current_cpu_data
.isa_level
== MIPS_CPU_ISA_I
) ||
631 (current_cpu_data
.isa_level
== MIPS_CPU_ISA_II
))
633 * We need to calibrate the counter but we don't have
636 do_gettimeoffset
= calibrate_div32_gettimeoffset
;
639 * We need to calibrate the counter but we *do* have
642 do_gettimeoffset
= calibrate_div64_gettimeoffset
;
644 /* We know counter frequency. Or we can get it. */
645 if (!mips_hpt_read
) {
646 /* No external high precision timer -- use R4k. */
647 mips_hpt_read
= c0_hpt_read
;
649 if (mips_timer_state
)
650 mips_hpt_init
= c0_hpt_init
;
652 /* No external timer interrupt -- use R4k. */
653 mips_hpt_init
= c0_hpt_timer_init
;
654 mips_timer_ack
= c0_timer_ack
;
657 if (!mips_hpt_frequency
)
658 mips_hpt_frequency
= calibrate_hpt();
660 do_gettimeoffset
= fixed_rate_gettimeoffset
;
662 /* Calculate cache parameters. */
663 cycles_per_jiffy
= (mips_hpt_frequency
+ HZ
/ 2) / HZ
;
665 /* sll32_usecs_per_cycle = 10^6 * 2^32 / mips_counter_freq */
666 do_div64_32(sll32_usecs_per_cycle
,
667 1000000, mips_hpt_frequency
/ 2,
670 /* Report the high precision timer rate for a reference. */
671 printk("Using %u.%03u MHz high precision timer.\n",
672 ((mips_hpt_frequency
+ 500) / 1000) / 1000,
673 ((mips_hpt_frequency
+ 500) / 1000) % 1000);
677 /* No timer interrupt ack (e.g. i8254). */
678 mips_timer_ack
= null_timer_ack
;
680 /* This sets up the high precision timer for the first interrupt. */
681 mips_hpt_init(mips_hpt_read());
684 * Call board specific timer interrupt setup.
686 * this pointer must be setup in machine setup routine.
688 * Even if a machine chooses to use a low-level timer interrupt,
689 * it still needs to setup the timer_irqaction.
690 * In that case, it might be better to set timer_irqaction.handler
691 * to be NULL function so that we are sure the high-level code
692 * is not invoked accidentally.
694 board_timer_setup(&timer_irqaction
);
698 #define STARTOFTIME 1970
699 #define SECDAY 86400L
700 #define SECYR (SECDAY * 365)
701 #define leapyear(y) ((!((y) % 4) && ((y) % 100)) || !((y) % 400))
702 #define days_in_year(y) (leapyear(y) ? 366 : 365)
703 #define days_in_month(m) (month_days[(m) - 1])
705 static int month_days
[12] = {
706 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
709 void to_tm(unsigned long tim
, struct rtc_time
*tm
)
714 gday
= day
= tim
/ SECDAY
;
717 /* Hours, minutes, seconds are easy */
718 tm
->tm_hour
= hms
/ 3600;
719 tm
->tm_min
= (hms
% 3600) / 60;
720 tm
->tm_sec
= (hms
% 3600) % 60;
722 /* Number of years in days */
723 for (i
= STARTOFTIME
; day
>= days_in_year(i
); i
++)
724 day
-= days_in_year(i
);
727 /* Number of months in days left */
728 if (leapyear(tm
->tm_year
))
729 days_in_month(FEBRUARY
) = 29;
730 for (i
= 1; day
>= days_in_month(i
); i
++)
731 day
-= days_in_month(i
);
732 days_in_month(FEBRUARY
) = 28;
733 tm
->tm_mon
= i
- 1; /* tm_mon starts from 0 to 11 */
735 /* Days are what is left over (+1) from all that. */
736 tm
->tm_mday
= day
+ 1;
739 * Determine the day of week
741 tm
->tm_wday
= (gday
+ 4) % 7; /* 1970/1/1 was Thursday */
744 EXPORT_SYMBOL(rtc_lock
);
745 EXPORT_SYMBOL(to_tm
);
746 EXPORT_SYMBOL(rtc_set_time
);
747 EXPORT_SYMBOL(rtc_get_time
);
749 unsigned long long sched_clock(void)
751 return (unsigned long long)jiffies
*(1000000000/HZ
);