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/cache.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)
50 DEFINE_SPINLOCK(rtc_lock
);
53 * By default we provide the null RTC ops
55 static unsigned long null_rtc_get_time(void)
57 return mktime(2000, 1, 1, 0, 0, 0);
60 static int null_rtc_set_time(unsigned long sec
)
65 unsigned long (*rtc_mips_get_time
)(void) = null_rtc_get_time
;
66 int (*rtc_mips_set_time
)(unsigned long) = null_rtc_set_time
;
67 int (*rtc_mips_set_mmss
)(unsigned long);
70 /* usecs per counter cycle, shifted to left by 32 bits */
71 static unsigned int sll32_usecs_per_cycle
;
73 /* how many counter cycles in a jiffy */
74 static unsigned long cycles_per_jiffy __read_mostly
;
76 /* Cycle counter value at the previous timer interrupt.. */
77 static unsigned int timerhi
, timerlo
;
79 /* expirelo is the count value for next CPU timer interrupt */
80 static unsigned int expirelo
;
84 * Null timer ack for systems not needing one (e.g. i8254).
86 static void null_timer_ack(void) { /* nothing */ }
89 * Null high precision timer functions for systems lacking one.
91 static unsigned int null_hpt_read(void)
96 static void null_hpt_init(unsigned int count
)
103 * Timer ack for an R4k-compatible timer of a known frequency.
105 static void c0_timer_ack(void)
109 #ifndef CONFIG_SOC_PNX8550 /* pnx8550 resets to zero */
110 /* Ack this timer interrupt and set the next one. */
111 expirelo
+= cycles_per_jiffy
;
113 write_c0_compare(expirelo
);
115 /* Check to see if we have missed any timer interrupts. */
116 while (((count
= read_c0_count()) - expirelo
) < 0x7fffffff) {
117 /* missed_timer_count++; */
118 expirelo
= count
+ cycles_per_jiffy
;
119 write_c0_compare(expirelo
);
124 * High precision timer functions for a R4k-compatible timer.
126 static unsigned int c0_hpt_read(void)
128 return read_c0_count();
131 /* For use solely as a high precision timer. */
132 static void c0_hpt_init(unsigned int count
)
134 write_c0_count(read_c0_count() - count
);
137 /* For use both as a high precision timer and an interrupt source. */
138 static void c0_hpt_timer_init(unsigned int count
)
140 count
= read_c0_count() - count
;
141 expirelo
= (count
/ cycles_per_jiffy
+ 1) * cycles_per_jiffy
;
142 write_c0_count(expirelo
- cycles_per_jiffy
);
143 write_c0_compare(expirelo
);
144 write_c0_count(count
);
147 int (*mips_timer_state
)(void);
148 void (*mips_timer_ack
)(void);
149 unsigned int (*mips_hpt_read
)(void);
150 void (*mips_hpt_init
)(unsigned int);
154 * This version of gettimeofday has microsecond resolution and better than
155 * microsecond precision on fast machines with cycle counter.
157 void do_gettimeofday(struct timeval
*tv
)
160 unsigned long usec
, sec
;
161 unsigned long max_ntp_tick
;
164 seq
= read_seqbegin(&xtime_lock
);
166 usec
= do_gettimeoffset();
169 * If time_adjust is negative then NTP is slowing the clock
170 * so make sure not to go into next possible interval.
171 * Better to lose some accuracy than have time go backwards..
173 if (unlikely(time_adjust
< 0)) {
174 max_ntp_tick
= (USEC_PER_SEC
/ HZ
) - tickadj
;
175 usec
= min(usec
, max_ntp_tick
);
179 usec
+= (xtime
.tv_nsec
/ 1000);
181 } while (read_seqretry(&xtime_lock
, seq
));
183 while (usec
>= 1000000) {
192 EXPORT_SYMBOL(do_gettimeofday
);
194 int do_settimeofday(struct timespec
*tv
)
196 time_t wtm_sec
, sec
= tv
->tv_sec
;
197 long wtm_nsec
, nsec
= tv
->tv_nsec
;
199 if ((unsigned long)tv
->tv_nsec
>= NSEC_PER_SEC
)
202 write_seqlock_irq(&xtime_lock
);
205 * This is revolting. We need to set "xtime" correctly. However,
206 * the value in this location is the value at the most recent update
207 * of wall time. Discover what correction gettimeofday() would have
208 * made, and then undo it!
210 nsec
-= do_gettimeoffset() * NSEC_PER_USEC
;
212 wtm_sec
= wall_to_monotonic
.tv_sec
+ (xtime
.tv_sec
- sec
);
213 wtm_nsec
= wall_to_monotonic
.tv_nsec
+ (xtime
.tv_nsec
- nsec
);
215 set_normalized_timespec(&xtime
, sec
, nsec
);
216 set_normalized_timespec(&wall_to_monotonic
, wtm_sec
, wtm_nsec
);
219 write_sequnlock_irq(&xtime_lock
);
224 EXPORT_SYMBOL(do_settimeofday
);
227 * Gettimeoffset routines. These routines returns the time duration
228 * since last timer interrupt in usecs.
230 * If the exact CPU counter frequency is known, use fixed_rate_gettimeoffset.
231 * Otherwise use calibrate_gettimeoffset()
233 * If the CPU does not have the counter register, you can either supply
234 * your own gettimeoffset() routine, or use null_gettimeoffset(), which
235 * gives the same resolution as HZ.
238 static unsigned long null_gettimeoffset(void)
244 /* The function pointer to one of the gettimeoffset funcs. */
245 unsigned long (*do_gettimeoffset
)(void) = null_gettimeoffset
;
248 static unsigned long fixed_rate_gettimeoffset(void)
253 /* Get last timer tick in absolute kernel time */
254 count
= mips_hpt_read();
256 /* .. relative to previous jiffy (32 bits is enough) */
259 __asm__("multu %1,%2"
261 : "r" (count
), "r" (sll32_usecs_per_cycle
)
262 : "lo", GCC_REG_ACCUM
);
265 * Due to possible jiffies inconsistencies, we need to check
266 * the result so that we'll get a timer that is monotonic.
268 if (res
>= USECS_PER_JIFFY
)
269 res
= USECS_PER_JIFFY
- 1;
276 * Cached "1/(clocks per usec) * 2^32" value.
277 * It has to be recalculated once each jiffy.
279 static unsigned long cached_quotient
;
281 /* Last jiffy when calibrate_divXX_gettimeoffset() was called. */
282 static unsigned long last_jiffies
;
285 * This is moved from dec/time.c:do_ioasic_gettimeoffset() by Maciej.
287 static unsigned long calibrate_div32_gettimeoffset(void)
290 unsigned long res
, tmp
;
291 unsigned long quotient
;
295 quotient
= cached_quotient
;
297 if (last_jiffies
!= tmp
) {
299 if (last_jiffies
!= 0) {
301 do_div64_32(r0
, timerhi
, timerlo
, tmp
);
302 do_div64_32(quotient
, USECS_PER_JIFFY
,
303 USECS_PER_JIFFY_FRAC
, r0
);
304 cached_quotient
= quotient
;
308 /* Get last timer tick in absolute kernel time */
309 count
= mips_hpt_read();
311 /* .. relative to previous jiffy (32 bits is enough) */
314 __asm__("multu %1,%2"
316 : "r" (count
), "r" (quotient
)
317 : "lo", GCC_REG_ACCUM
);
320 * Due to possible jiffies inconsistencies, we need to check
321 * the result so that we'll get a timer that is monotonic.
323 if (res
>= USECS_PER_JIFFY
)
324 res
= USECS_PER_JIFFY
- 1;
329 static unsigned long calibrate_div64_gettimeoffset(void)
332 unsigned long res
, tmp
;
333 unsigned long quotient
;
337 quotient
= cached_quotient
;
339 if (last_jiffies
!= tmp
) {
343 __asm__(".set push\n\t"
355 : "=&r" (quotient
), "=&r" (r0
)
356 : "r" (timerhi
), "m" (timerlo
),
357 "r" (tmp
), "r" (USECS_PER_JIFFY
),
358 "r" (USECS_PER_JIFFY_FRAC
)
359 : "hi", "lo", GCC_REG_ACCUM
);
360 cached_quotient
= quotient
;
364 /* Get last timer tick in absolute kernel time */
365 count
= mips_hpt_read();
367 /* .. relative to previous jiffy (32 bits is enough) */
370 __asm__("multu %1,%2"
372 : "r" (count
), "r" (quotient
)
373 : "lo", GCC_REG_ACCUM
);
376 * Due to possible jiffies inconsistencies, we need to check
377 * the result so that we'll get a timer that is monotonic.
379 if (res
>= USECS_PER_JIFFY
)
380 res
= USECS_PER_JIFFY
- 1;
386 /* last time when xtime and rtc are sync'ed up */
387 static long last_rtc_update
;
390 * local_timer_interrupt() does profiling and process accounting
391 * on a per-CPU basis.
393 * In UP mode, it is invoked from the (global) timer_interrupt.
395 * In SMP mode, it might invoked by per-CPU timer interrupt, or
396 * a broadcasted inter-processor interrupt which itself is triggered
397 * by the global timer interrupt.
399 void local_timer_interrupt(int irq
, void *dev_id
, struct pt_regs
*regs
)
402 profile_tick(CPU_PROFILING
, regs
);
403 update_process_times(user_mode(regs
));
407 * High-level timer interrupt service routines. This function
408 * is set as irqaction->handler and is invoked through do_IRQ.
410 irqreturn_t
timer_interrupt(int irq
, void *dev_id
, struct pt_regs
*regs
)
415 write_seqlock(&xtime_lock
);
417 count
= mips_hpt_read();
420 /* Update timerhi/timerlo for intra-jiffy calibration. */
421 timerhi
+= count
< timerlo
; /* Wrap around */
425 * call the generic timer interrupt handling
430 * If we have an externally synchronized Linux clock, then update
431 * CMOS clock accordingly every ~11 minutes. rtc_mips_set_time() has to be
432 * called as close as possible to 500 ms before the new second starts.
435 xtime
.tv_sec
> last_rtc_update
+ 660 &&
436 (xtime
.tv_nsec
/ 1000) >= 500000 - ((unsigned) TICK_SIZE
) / 2 &&
437 (xtime
.tv_nsec
/ 1000) <= 500000 + ((unsigned) TICK_SIZE
) / 2) {
438 if (rtc_mips_set_mmss(xtime
.tv_sec
) == 0) {
439 last_rtc_update
= xtime
.tv_sec
;
441 /* do it again in 60 s */
442 last_rtc_update
= xtime
.tv_sec
- 600;
447 * If jiffies has overflown in this timer_interrupt, we must
448 * update the timer[hi]/[lo] to make fast gettimeoffset funcs
449 * quotient calc still valid. -arca
451 * The first timer interrupt comes late as interrupts are
452 * enabled long after timers are initialized. Therefore the
453 * high precision timer is fast, leading to wrong gettimeoffset()
454 * calculations. We deal with it by setting it based on the
455 * number of its ticks between the second and the third interrupt.
456 * That is still somewhat imprecise, but it's a good estimate.
461 static unsigned int prev_count
;
462 static int hpt_initialized
;
466 timerhi
= timerlo
= 0;
467 mips_hpt_init(count
);
473 if (!hpt_initialized
) {
474 unsigned int c3
= 3 * (count
- prev_count
);
478 mips_hpt_init(count
- c3
);
487 write_sequnlock(&xtime_lock
);
490 * In UP mode, we call local_timer_interrupt() to do profiling
491 * and process accouting.
493 * In SMP mode, local_timer_interrupt() is invoked by appropriate
494 * low-level local timer interrupt handler.
496 local_timer_interrupt(irq
, dev_id
, regs
);
501 int null_perf_irq(struct pt_regs
*regs
)
506 int (*perf_irq
)(struct pt_regs
*regs
) = null_perf_irq
;
508 EXPORT_SYMBOL(null_perf_irq
);
509 EXPORT_SYMBOL(perf_irq
);
511 asmlinkage
void ll_timer_interrupt(int irq
, struct pt_regs
*regs
)
513 int r2
= cpu_has_mips_r2
;
516 kstat_this_cpu
.irqs
[irq
]++;
520 * Before R2 of the architecture there was no way to see if a
521 * performance counter interrupt was pending, so we have to run the
522 * performance counter interrupt handler anyway.
524 if (!r2
|| (read_c0_cause() & (1 << 26)))
528 /* we keep interrupt disabled all the time */
529 if (!r2
|| (read_c0_cause() & (1 << 30)))
530 timer_interrupt(irq
, NULL
, regs
);
536 asmlinkage
void ll_local_timer_interrupt(int irq
, struct pt_regs
*regs
)
539 if (smp_processor_id() != 0)
540 kstat_this_cpu
.irqs
[irq
]++;
542 /* we keep interrupt disabled all the time */
543 local_timer_interrupt(irq
, NULL
, regs
);
549 * time_init() - it does the following things.
551 * 1) board_time_init() -
552 * a) (optional) set up RTC routines,
553 * b) (optional) calibrate and set the mips_hpt_frequency
554 * (only needed if you intended to use fixed_rate_gettimeoffset
555 * or use cpu counter as timer interrupt source)
556 * 2) setup xtime based on rtc_mips_get_time().
557 * 3) choose a appropriate gettimeoffset routine.
558 * 4) calculate a couple of cached variables for later usage
559 * 5) plat_timer_setup() -
560 * a) (optional) over-write any choices made above by time_init().
561 * b) machine specific code should setup the timer irqaction.
562 * c) enable the timer interrupt
565 void (*board_time_init
)(void);
567 unsigned int mips_hpt_frequency
;
569 static struct irqaction timer_irqaction
= {
570 .handler
= timer_interrupt
,
571 .flags
= IRQF_DISABLED
,
575 static unsigned int __init
calibrate_hpt(void)
578 u32 hpt_start
, hpt_end
, hpt_count
, hz
;
580 const int loops
= HZ
/ 10;
585 * We want to calibrate for 0.1s, but to avoid a 64-bit
586 * division we round the number of loops up to the nearest
589 while (loops
> 1 << log_2_loops
)
591 i
= 1 << log_2_loops
;
594 * Wait for a rising edge of the timer interrupt.
596 while (mips_timer_state());
597 while (!mips_timer_state());
600 * Now see how many high precision timer ticks happen
601 * during the calculated number of periods between timer
604 hpt_start
= mips_hpt_read();
606 while (mips_timer_state());
607 while (!mips_timer_state());
609 hpt_end
= mips_hpt_read();
611 hpt_count
= hpt_end
- hpt_start
;
613 frequency
= (u64
)hpt_count
* (u64
)hz
;
615 return frequency
>> log_2_loops
;
618 void __init
time_init(void)
623 if (!rtc_mips_set_mmss
)
624 rtc_mips_set_mmss
= rtc_mips_set_time
;
626 xtime
.tv_sec
= rtc_mips_get_time();
629 set_normalized_timespec(&wall_to_monotonic
,
630 -xtime
.tv_sec
, -xtime
.tv_nsec
);
632 /* Choose appropriate high precision timer routines. */
633 if (!cpu_has_counter
&& !mips_hpt_read
) {
634 /* No high precision timer -- sorry. */
635 mips_hpt_read
= null_hpt_read
;
636 mips_hpt_init
= null_hpt_init
;
637 } else if (!mips_hpt_frequency
&& !mips_timer_state
) {
638 /* A high precision timer of unknown frequency. */
639 if (!mips_hpt_read
) {
640 /* No external high precision timer -- use R4k. */
641 mips_hpt_read
= c0_hpt_read
;
642 mips_hpt_init
= c0_hpt_init
;
645 if (cpu_has_mips32r1
|| cpu_has_mips32r2
||
646 (current_cpu_data
.isa_level
== MIPS_CPU_ISA_I
) ||
647 (current_cpu_data
.isa_level
== MIPS_CPU_ISA_II
))
649 * We need to calibrate the counter but we don't have
652 do_gettimeoffset
= calibrate_div32_gettimeoffset
;
655 * We need to calibrate the counter but we *do* have
658 do_gettimeoffset
= calibrate_div64_gettimeoffset
;
660 /* We know counter frequency. Or we can get it. */
661 if (!mips_hpt_read
) {
662 /* No external high precision timer -- use R4k. */
663 mips_hpt_read
= c0_hpt_read
;
665 if (mips_timer_state
)
666 mips_hpt_init
= c0_hpt_init
;
668 /* No external timer interrupt -- use R4k. */
669 mips_hpt_init
= c0_hpt_timer_init
;
670 mips_timer_ack
= c0_timer_ack
;
673 if (!mips_hpt_frequency
)
674 mips_hpt_frequency
= calibrate_hpt();
676 do_gettimeoffset
= fixed_rate_gettimeoffset
;
678 /* Calculate cache parameters. */
679 cycles_per_jiffy
= (mips_hpt_frequency
+ HZ
/ 2) / HZ
;
681 /* sll32_usecs_per_cycle = 10^6 * 2^32 / mips_counter_freq */
682 do_div64_32(sll32_usecs_per_cycle
,
683 1000000, mips_hpt_frequency
/ 2,
686 /* Report the high precision timer rate for a reference. */
687 printk("Using %u.%03u MHz high precision timer.\n",
688 ((mips_hpt_frequency
+ 500) / 1000) / 1000,
689 ((mips_hpt_frequency
+ 500) / 1000) % 1000);
693 /* No timer interrupt ack (e.g. i8254). */
694 mips_timer_ack
= null_timer_ack
;
696 /* This sets up the high precision timer for the first interrupt. */
697 mips_hpt_init(mips_hpt_read());
700 * Call board specific timer interrupt setup.
702 * this pointer must be setup in machine setup routine.
704 * Even if a machine chooses to use a low-level timer interrupt,
705 * it still needs to setup the timer_irqaction.
706 * In that case, it might be better to set timer_irqaction.handler
707 * to be NULL function so that we are sure the high-level code
708 * is not invoked accidentally.
710 plat_timer_setup(&timer_irqaction
);
714 #define STARTOFTIME 1970
715 #define SECDAY 86400L
716 #define SECYR (SECDAY * 365)
717 #define leapyear(y) ((!((y) % 4) && ((y) % 100)) || !((y) % 400))
718 #define days_in_year(y) (leapyear(y) ? 366 : 365)
719 #define days_in_month(m) (month_days[(m) - 1])
721 static int month_days
[12] = {
722 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
725 void to_tm(unsigned long tim
, struct rtc_time
*tm
)
730 gday
= day
= tim
/ SECDAY
;
733 /* Hours, minutes, seconds are easy */
734 tm
->tm_hour
= hms
/ 3600;
735 tm
->tm_min
= (hms
% 3600) / 60;
736 tm
->tm_sec
= (hms
% 3600) % 60;
738 /* Number of years in days */
739 for (i
= STARTOFTIME
; day
>= days_in_year(i
); i
++)
740 day
-= days_in_year(i
);
743 /* Number of months in days left */
744 if (leapyear(tm
->tm_year
))
745 days_in_month(FEBRUARY
) = 29;
746 for (i
= 1; day
>= days_in_month(i
); i
++)
747 day
-= days_in_month(i
);
748 days_in_month(FEBRUARY
) = 28;
749 tm
->tm_mon
= i
- 1; /* tm_mon starts from 0 to 11 */
751 /* Days are what is left over (+1) from all that. */
752 tm
->tm_mday
= day
+ 1;
755 * Determine the day of week
757 tm
->tm_wday
= (gday
+ 4) % 7; /* 1970/1/1 was Thursday */
760 EXPORT_SYMBOL(rtc_lock
);
761 EXPORT_SYMBOL(to_tm
);
762 EXPORT_SYMBOL(rtc_mips_set_time
);
763 EXPORT_SYMBOL(rtc_mips_get_time
);
765 unsigned long long sched_clock(void)
767 return (unsigned long long)jiffies
*(1000000000/HZ
);