/*
* arch/xtensa/kernel/time.c
*
* Timer and clock support.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2005 Tensilica Inc.
*
* Chris Zankel <chris@zankel.net>
*/
#include <linux/errno.h>
#include <linux/time.h>
#include <linux/timex.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/irq.h>
#include <linux/profile.h>
#include <linux/delay.h>
#include <asm/timex.h>
#include <asm/platform.h>
DEFINE_SPINLOCK(rtc_lock);
EXPORT_SYMBOL(rtc_lock);
#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
unsigned long ccount_per_jiffy; /* per 1/HZ */
unsigned long ccount_nsec; /* nsec per ccount increment */
#endif
unsigned int last_ccount_stamp;
static long last_rtc_update = 0;
/*
* Scheduler clock - returns current tim in nanosec units.
*/
unsigned long long sched_clock(void)
{
return (unsigned long long)jiffies * (1000000000 / HZ);
}
static irqreturn_t timer_interrupt(int irq, void *dev_id, struct pt_regs *regs);
static struct irqaction timer_irqaction = {
.handler = timer_interrupt,
.flags = IRQF_DISABLED,
.name = "timer",
};
void __init time_init(void)
{
time_t sec_o, sec_n = 0;
/* The platform must provide a function to calibrate the processor
* speed for the CALIBRATE.
*/
#ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
printk("Calibrating CPU frequency ");
platform_calibrate_ccount();
printk("%d.%02d MHz\n", (int)ccount_per_jiffy/(1000000/HZ),
(int)(ccount_per_jiffy/(10000/HZ))%100);
#endif
/* Set time from RTC (if provided) */
if (platform_get_rtc_time(&sec_o) == 0)
while (platform_get_rtc_time(&sec_n))
if (sec_o != sec_n)
break;
xtime.tv_nsec = 0;
last_rtc_update = xtime.tv_sec = sec_n;
last_ccount_stamp = get_ccount();
set_normalized_timespec(&wall_to_monotonic,
-xtime.tv_sec, -xtime.tv_nsec);
/* Initialize the linux timer interrupt. */
setup_irq(LINUX_TIMER_INT, &timer_irqaction);
set_linux_timer(get_ccount() + CCOUNT_PER_JIFFY);
}
int do_settimeofday(struct timespec *tv)
{
time_t wtm_sec, sec = tv->tv_sec;
long wtm_nsec, nsec = tv->tv_nsec;
unsigned long ccount;
if ((unsigned long)tv->tv_nsec >= NSEC_PER_SEC)
return -EINVAL;
write_seqlock_irq(&xtime_lock);
/* This is revolting. We need to set "xtime" correctly. However, the
* value in this location is the value at the most recent update of
* wall time. Discover what correction gettimeofday() would have
* made, and then undo it!
*/
ccount = get_ccount();
nsec -= (ccount - last_ccount_stamp) * CCOUNT_NSEC;
wtm_sec = wall_to_monotonic.tv_sec + (xtime.tv_sec - sec);
wtm_nsec = wall_to_monotonic.tv_nsec + (xtime.tv_nsec - nsec);
set_normalized_timespec(&xtime, sec, nsec);
set_normalized_timespec(&wall_to_monotonic, wtm_sec, wtm_nsec);
ntp_clear();
write_sequnlock_irq(&xtime_lock);
return 0;
}
EXPORT_SYMBOL(do_settimeofday);
void do_gettimeofday(struct timeval *tv)
{
unsigned long flags;
unsigned long sec, usec, delta, seq;
do {
seq = read_seqbegin_irqsave(&xtime_lock, flags);
delta = get_ccount() - last_ccount_stamp;
sec = xtime.tv_sec;
usec = (xtime.tv_nsec / NSEC_PER_USEC);
} while (read_seqretry_irqrestore(&xtime_lock, seq, flags));
usec += (delta * CCOUNT_NSEC) / NSEC_PER_USEC;
for (; usec >= 1000000; sec++, usec -= 1000000)
;
tv->tv_sec = sec;
tv->tv_usec = usec;
}
EXPORT_SYMBOL(do_gettimeofday);
/*
* The timer interrupt is called HZ times per second.
*/
irqreturn_t timer_interrupt (int irq, void *dev_id, struct pt_regs *regs)
{
unsigned long next;
next = get_linux_timer();
again:
while ((signed long)(get_ccount() - next) > 0) {
profile_tick(CPU_PROFILING, regs);
#ifndef CONFIG_SMP
update_process_times(user_mode(regs));
#endif
write_seqlock(&xtime_lock);
last_ccount_stamp = next;
next += CCOUNT_PER_JIFFY;
do_timer (1); /* Linux handler in kernel/timer.c */
if (ntp_synced() &&
xtime.tv_sec - last_rtc_update >= 659 &&
abs((xtime.tv_nsec/1000)-(1000000-1000000/HZ))<5000000/HZ) {
if (platform_set_rtc_time(xtime.tv_sec+1) == 0)
last_rtc_update = xtime.tv_sec+1;
else
/* Do it again in 60 s */
last_rtc_update += 60;
}
write_sequnlock(&xtime_lock);
}
/* NOTE: writing CCOMPAREn clears the interrupt. */
set_linux_timer (next);
/* Make sure we didn't miss any tick... */
if ((signed long)(get_ccount() - next) > 0)
goto again;
/* Allow platform to do something useful (Wdog). */
platform_heartbeat();
return IRQ_HANDLED;
}
#ifndef CONFIG_GENERIC_CALIBRATE_DELAY
void __devinit calibrate_delay(void)
{
loops_per_jiffy = CCOUNT_PER_JIFFY;
printk("Calibrating delay loop (skipped)... "
"%lu.%02lu BogoMIPS preset\n",
loops_per_jiffy/(1000000/HZ),
(loops_per_jiffy/(10000/HZ)) % 100);
}
#endif
