Logo Search packages:      
Sourcecode: linux version File versions  Download package

time.c

/*
 * 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 nsec_per_ccount;            /* nsec per ccount increment */
#endif

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);
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;

      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 delta;

      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!
       */

      delta = CCOUNT_PER_JIFFY;
      delta += get_ccount() - get_linux_timer();
      nsec -= delta * NSEC_PER_CCOUNT;

      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 volatile sec, usec, delta, seq;

      do {
            seq = read_seqbegin_irqsave(&xtime_lock, flags);

            sec = xtime.tv_sec;
            usec = (xtime.tv_nsec / NSEC_PER_USEC);

            delta = get_linux_timer() - get_ccount();

      } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));

      usec += (((unsigned long) CCOUNT_PER_JIFFY - delta)
             * (unsigned long) NSEC_PER_CCOUNT) / 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)
{

      unsigned long next;

      next = get_linux_timer();

again:
      while ((signed long)(get_ccount() - next) > 0) {

            profile_tick(CPU_PROFILING);
#ifndef CONFIG_SMP
            update_process_times(user_mode(get_irq_regs()));
#endif

            write_seqlock(&xtime_lock);

            do_timer(1); /* Linux handler in kernel/timer.c */

            /* Note that writing CCOMPARE clears the interrupt. */

            next += CCOUNT_PER_JIFFY;
            set_linux_timer(next);

            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);
      }

      /* Allow platform to do something useful (Wdog). */

      platform_heartbeat();

      /* Make sure we didn't miss any tick... */

      if ((signed long)(get_ccount() - next) > 0)
            goto again;

      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


Generated by  Doxygen 1.6.0   Back to index