2 * linux/arch/v850/kernel/time.c -- Arch-dependent timer functions
4 * Copyright (C) 1991, 1992, 1995, 2001, 2002 Linus Torvalds
6 * This file contains the v850-specific time handling details.
7 * Most of the stuff is located in the machine specific files.
9 * 1997-09-10 Updated NTP code according to technical memorandum Jan '96
10 * "A Kernel Model for Precision Timekeeping" by Dave Mills
13 #include <linux/errno.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/param.h>
17 #include <linux/string.h>
19 #include <linux/interrupt.h>
20 #include <linux/time.h>
21 #include <linux/timex.h>
22 #include <linux/profile.h>
28 #define TICK_SIZE (tick_nsec / 1000)
31 * timer_interrupt() needs to keep up the real-time clock,
32 * as well as call the "do_timer()" routine every clocktick
34 static irqreturn_t
timer_interrupt (int irq
, void *dummy
, struct pt_regs
*regs
)
37 /* last time the cmos clock got updated */
38 static long last_rtc_update
=0;
41 /* may need to kick the hardware timer */
47 update_process_times(user_mode(regs
));
49 profile_tick(CPU_PROFILING
, regs
);
52 * If we have an externally synchronized Linux clock, then update
53 * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
54 * called as close as possible to 500 ms before the new second starts.
57 xtime
.tv_sec
> last_rtc_update
+ 660 &&
58 (xtime
.tv_nsec
/ 1000) >= 500000 - ((unsigned) TICK_SIZE
) / 2 &&
59 (xtime
.tv_nsec
/ 1000) <= 500000 + ((unsigned) TICK_SIZE
) / 2) {
60 if (set_rtc_mmss (xtime
.tv_sec
) == 0)
61 last_rtc_update
= xtime
.tv_sec
;
63 last_rtc_update
= xtime
.tv_sec
- 600; /* do it again in 60 s */
65 #ifdef CONFIG_HEARTBEAT
66 /* use power LED as a heartbeat instead -- much more useful
67 for debugging -- based on the version for PReP by Cort */
68 /* acts like an actual heart beat -- ie thump-thump-pause... */
70 static unsigned cnt
= 0, period
= 0, dist
= 0;
72 if (cnt
== 0 || cnt
== dist
)
74 else if (cnt
== 7 || cnt
== dist
+7)
79 /* The hyperbolic function below modifies the heartbeat period
80 * length in dependency of the current (5min) load. It goes
81 * through the points f(0)=126, f(1)=86, f(5)=51,
83 period
= ((672<<FSHIFT
)/(5*avenrun
[0]+(7<<FSHIFT
))) + 30;
87 #endif /* CONFIG_HEARTBEAT */
94 * This version of gettimeofday has near microsecond resolution.
96 void do_gettimeofday (struct timeval
*tv
)
98 #if 0 /* DAVIDM later if possible */
99 extern volatile unsigned long lost_ticks
;
103 unsigned long usec
, sec
;
107 seq
= read_seqbegin_irqsave(&xtime_lock
, flags
);
110 usec
= mach_gettimeoffset
? mach_gettimeoffset () : 0;
114 #if 0 /* DAVIDM later if possible */
117 usec
+= lost
* (1000000/HZ
);
120 usec
+= xtime
.tv_nsec
/ 1000;
121 } while (read_seqretry_irqrestore(&xtime_lock
, seq
, flags
));
123 while (usec
>= 1000000) {
132 EXPORT_SYMBOL(do_gettimeofday
);
134 int do_settimeofday(struct timespec
*tv
)
136 if ((unsigned long)tv
->tv_nsec
>= NSEC_PER_SEC
)
139 write_seqlock_irq (&xtime_lock
);
141 /* This is revolting. We need to set the xtime.tv_nsec
142 * correctly. However, the value in this location is
143 * is value at the last tick.
144 * Discover what correction gettimeofday
145 * would have done, and then undo it!
148 tv
->tv_nsec
-= mach_gettimeoffset() * 1000;
151 while (tv
->tv_nsec
< 0) {
152 tv
->tv_nsec
+= NSEC_PER_SEC
;
156 xtime
.tv_sec
= tv
->tv_sec
;
157 xtime
.tv_nsec
= tv
->tv_nsec
;
161 write_sequnlock_irq (&xtime_lock
);
166 EXPORT_SYMBOL(do_settimeofday
);
168 static int timer_dev_id
;
169 static struct irqaction timer_irqaction
= {
178 void time_init (void)
180 mach_gettimeofday (&xtime
);
181 mach_sched_init (&timer_irqaction
);