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time.c

/* time.c: FRV arch-specific time handling
 *
 * Copyright (C) 2003-5 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 * - Derived from arch/m68k/kernel/time.c
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/param.h>
#include <linux/string.h>
#include <linux/interrupt.h>
#include <linux/profile.h>
#include <linux/irq.h>
#include <linux/mm.h>

#include <asm/io.h>
#include <asm/timer-regs.h>
#include <asm/mb-regs.h>
#include <asm/mb86943a.h>

#include <linux/timex.h>

#define TICK_SIZE (tick_nsec / 1000)

unsigned long __nongprelbss __clkin_clock_speed_HZ;
unsigned long __nongprelbss __ext_bus_clock_speed_HZ;
unsigned long __nongprelbss __res_bus_clock_speed_HZ;
unsigned long __nongprelbss __sdram_clock_speed_HZ;
unsigned long __nongprelbss __core_bus_clock_speed_HZ;
unsigned long __nongprelbss __core_clock_speed_HZ;
unsigned long __nongprelbss __dsu_clock_speed_HZ;
unsigned long __nongprelbss __serial_clock_speed_HZ;
unsigned long __delay_loops_MHz;

static irqreturn_t timer_interrupt(int irq, void *dummy);

static struct irqaction timer_irq  = {
      .handler = timer_interrupt,
      .flags = IRQF_DISABLED,
      .name = "timer",
};

static inline int set_rtc_mmss(unsigned long nowtime)
{
      return -1;
}

/*
 * timer_interrupt() needs to keep up the real-time clock,
 * as well as call the "do_timer()" routine every clocktick
 */
static irqreturn_t timer_interrupt(int irq, void *dummy)
{
      /* last time the cmos clock got updated */
      static long last_rtc_update = 0;

      profile_tick(CPU_PROFILING);
      /*
       * Here we are in the timer irq handler. We just have irqs locally
       * disabled but we don't know if the timer_bh is running on the other
       * CPU. We need to avoid to SMP race with it. NOTE: we don't need
       * the irq version of write_lock because as just said we have irq
       * locally disabled. -arca
       */
      write_seqlock(&xtime_lock);

      do_timer(1);

      /*
       * If we have an externally synchronized Linux clock, then update
       * CMOS clock accordingly every ~11 minutes. Set_rtc_mmss() has to be
       * called as close as possible to 500 ms before the new second starts.
       */
      if (ntp_synced() &&
          xtime.tv_sec > last_rtc_update + 660 &&
          (xtime.tv_nsec / 1000) >= 500000 - ((unsigned) TICK_SIZE) / 2 &&
          (xtime.tv_nsec / 1000) <= 500000 + ((unsigned) TICK_SIZE) / 2
          ) {
            if (set_rtc_mmss(xtime.tv_sec) == 0)
                  last_rtc_update = xtime.tv_sec;
            else
                  last_rtc_update = xtime.tv_sec - 600; /* do it again in 60 s */
      }

#ifdef CONFIG_HEARTBEAT
      static unsigned short n;
      n++;
      __set_LEDS(n);
#endif /* CONFIG_HEARTBEAT */

      write_sequnlock(&xtime_lock);

      update_process_times(user_mode(get_irq_regs()));

      return IRQ_HANDLED;
}

void time_divisor_init(void)
{
      unsigned short base, pre, prediv;

      /* set the scheduling timer going */
      pre = 1;
      prediv = 4;
      base = __res_bus_clock_speed_HZ / pre / HZ / (1 << prediv);

      __set_TPRV(pre);
      __set_TxCKSL_DATA(0, prediv);
      __set_TCTR(TCTR_SC_CTR0 | TCTR_RL_RW_LH8 | TCTR_MODE_2);
      __set_TCSR_DATA(0, base & 0xff);
      __set_TCSR_DATA(0, base >> 8);
}

void time_init(void)
{
      unsigned int year, mon, day, hour, min, sec;

      extern void arch_gettod(int *year, int *mon, int *day, int *hour, int *min, int *sec);

      /* FIX by dqg : Set to zero for platforms that don't have tod */
      /* without this time is undefined and can overflow time_t, causing  */
      /* very strange errors */
      year = 1980;
      mon = day = 1;
      hour = min = sec = 0;
      arch_gettod (&year, &mon, &day, &hour, &min, &sec);

      if ((year += 1900) < 1970)
            year += 100;
      xtime.tv_sec = mktime(year, mon, day, hour, min, sec);
      xtime.tv_nsec = 0;

      /* install scheduling interrupt handler */
      setup_irq(IRQ_CPU_TIMER0, &timer_irq);

      time_divisor_init();
}

/*
 * Scheduler clock - returns current time in nanosec units.
 */
unsigned long long sched_clock(void)
{
      return jiffies_64 * (1000000000 / HZ);
}

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