linux/arch/cris/kernel/time.c
Jesper Nilsson 60dbd66331 CRIS: GENERIC_TIME fixes
GENERIC_TIME was not functional for CRIS, giving random backward
time jumps.

For CRISv32 implement a new clocksource using the free running counter
and ditch the arch_gettimeoffset.

The random time jumps still existed, but turned out to be the write_seqlock
which was missing around our do_timer() call.

So switch over to GENERIC_TIME using the clocksource for CRISv32.

CRISv10 doesn't have the free running counter needed for the
clocksource trick, but we can still use GENERIC_TIME with
arch_gettimeoffset.

Unfortunately, there were problems in using the prescaler register
to timer0 for the gettimeoffset calculation, so it is now ignored,
making our resolution worse by the tune of 40usec (0.4%) worst case.

At the same time, clean up some formatting and use NSEC_PER_SEC
instead of 1000000000.

Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>
2010-08-04 12:58:55 +02:00

169 lines
3.8 KiB
C

/*
* linux/arch/cris/kernel/time.c
*
* Copyright (C) 1991, 1992, 1995 Linus Torvalds
* Copyright (C) 1999, 2000, 2001 Axis Communications AB
*
* 1994-07-02 Alan Modra
* fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
* 1995-03-26 Markus Kuhn
* fixed 500 ms bug at call to set_rtc_mmss, fixed DS12887
* precision CMOS clock update
* 1996-05-03 Ingo Molnar
* fixed time warps in do_[slow|fast]_gettimeoffset()
* 1997-09-10 Updated NTP code according to technical memorandum Jan '96
* "A Kernel Model for Precision Timekeeping" by Dave Mills
*
* Linux/CRIS specific code:
*
* Authors: Bjorn Wesen
* Johan Adolfsson
*
*/
#include <asm/rtc.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/param.h>
#include <linux/jiffies.h>
#include <linux/bcd.h>
#include <linux/timex.h>
#include <linux/init.h>
#include <linux/profile.h>
#include <linux/sched.h> /* just for sched_clock() - funny that */
int have_rtc; /* used to remember if we have an RTC or not */;
#define TICK_SIZE tick
extern unsigned long loops_per_jiffy; /* init/main.c */
unsigned long loops_per_usec;
#ifdef CONFIG_ARCH_USES_GETTIMEOFFSET
extern unsigned long do_slow_gettimeoffset(void);
static unsigned long (*do_gettimeoffset)(void) = do_slow_gettimeoffset;
u32 arch_gettimeoffset(void)
{
return do_gettimeoffset() * 1000;
}
#endif
/*
* BUG: This routine does not handle hour overflow properly; it just
* sets the minutes. Usually you'll only notice that after reboot!
*/
int set_rtc_mmss(unsigned long nowtime)
{
int retval = 0;
int real_seconds, real_minutes, cmos_minutes;
printk(KERN_DEBUG "set_rtc_mmss(%lu)\n", nowtime);
if(!have_rtc)
return 0;
cmos_minutes = CMOS_READ(RTC_MINUTES);
cmos_minutes = bcd2bin(cmos_minutes);
/*
* since we're only adjusting minutes and seconds,
* don't interfere with hour overflow. This avoids
* messing with unknown time zones but requires your
* RTC not to be off by more than 15 minutes
*/
real_seconds = nowtime % 60;
real_minutes = nowtime / 60;
if (((abs(real_minutes - cmos_minutes) + 15)/30) & 1)
real_minutes += 30; /* correct for half hour time zone */
real_minutes %= 60;
if (abs(real_minutes - cmos_minutes) < 30) {
real_seconds = bin2bcd(real_seconds);
real_minutes = bin2bcd(real_minutes);
CMOS_WRITE(real_seconds,RTC_SECONDS);
CMOS_WRITE(real_minutes,RTC_MINUTES);
} else {
printk(KERN_WARNING
"set_rtc_mmss: can't update from %d to %d\n",
cmos_minutes, real_minutes);
retval = -1;
}
return retval;
}
/* grab the time from the RTC chip */
unsigned long
get_cmos_time(void)
{
unsigned int year, mon, day, hour, min, sec;
if(!have_rtc)
return 0;
sec = CMOS_READ(RTC_SECONDS);
min = CMOS_READ(RTC_MINUTES);
hour = CMOS_READ(RTC_HOURS);
day = CMOS_READ(RTC_DAY_OF_MONTH);
mon = CMOS_READ(RTC_MONTH);
year = CMOS_READ(RTC_YEAR);
sec = bcd2bin(sec);
min = bcd2bin(min);
hour = bcd2bin(hour);
day = bcd2bin(day);
mon = bcd2bin(mon);
year = bcd2bin(year);
if ((year += 1900) < 1970)
year += 100;
return mktime(year, mon, day, hour, min, sec);
}
int update_persistent_clock(struct timespec now)
{
return set_rtc_mmss(now.tv_sec);
}
void read_persistent_clock(struct timespec *ts)
{
ts->tv_sec = get_cmos_time();
ts->tv_nsec = 0;
}
extern void cris_profile_sample(struct pt_regs* regs);
void
cris_do_profile(struct pt_regs* regs)
{
#ifdef CONFIG_SYSTEM_PROFILER
cris_profile_sample(regs);
#endif
#ifdef CONFIG_PROFILING
profile_tick(CPU_PROFILING);
#endif
}
unsigned long long sched_clock(void)
{
return (unsigned long long)jiffies * (NSEC_PER_SEC / HZ) +
get_ns_in_jiffie();
}
static int
__init init_udelay(void)
{
loops_per_usec = (loops_per_jiffy * HZ) / 1000000;
return 0;
}
__initcall(init_udelay);