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time.c

/*
 *  arch/sh/kernel/time.c
 *
 *  Copyright (C) 1999  Tetsuya Okada & Niibe Yutaka
 *  Copyright (C) 2000  Philipp Rumpf <prumpf@tux.org>
 *  Copyright (C) 2002 - 2007  Paul Mundt
 *  Copyright (C) 2002  M. R. Brown  <mrbrown@linux-sh.org>
 *
 *  Some code taken from i386 version.
 *    Copyright (C) 1991, 1992, 1995  Linus Torvalds
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/profile.h>
#include <linux/timex.h>
#include <linux/sched.h>
#include <linux/clockchips.h>
#include <asm/clock.h>
#include <asm/rtc.h>
#include <asm/timer.h>
#include <asm/kgdb.h>

struct sys_timer *sys_timer;

/* Move this somewhere more sensible.. */
DEFINE_SPINLOCK(rtc_lock);
EXPORT_SYMBOL(rtc_lock);

/* Dummy RTC ops */
static void null_rtc_get_time(struct timespec *tv)
{
      tv->tv_sec = mktime(2000, 1, 1, 0, 0, 0);
      tv->tv_nsec = 0;
}

static int null_rtc_set_time(const time_t secs)
{
      return 0;
}

/*
 * Null high precision timer functions for systems lacking one.
 */
static cycle_t null_hpt_read(void)
{
      return 0;
}

void (*rtc_sh_get_time)(struct timespec *) = null_rtc_get_time;
int (*rtc_sh_set_time)(const time_t) = null_rtc_set_time;

#ifndef CONFIG_GENERIC_TIME
void do_gettimeofday(struct timeval *tv)
{
      unsigned long flags;
      unsigned long seq;
      unsigned long usec, sec;

      do {
            /*
             * Turn off IRQs when grabbing xtime_lock, so that
             * the sys_timer get_offset code doesn't have to handle it.
             */
            seq = read_seqbegin_irqsave(&xtime_lock, flags);
            usec = get_timer_offset();
            sec = xtime.tv_sec;
            usec += xtime.tv_nsec / NSEC_PER_USEC;
      } while (read_seqretry_irqrestore(&xtime_lock, seq, flags));

      while (usec >= 1000000) {
            usec -= 1000000;
            sec++;
      }

      tv->tv_sec = sec;
      tv->tv_usec = usec;
}
EXPORT_SYMBOL(do_gettimeofday);

int do_settimeofday(struct timespec *tv)
{
      time_t wtm_sec, sec = tv->tv_sec;
      long wtm_nsec, nsec = tv->tv_nsec;

      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!
       */
      nsec -= get_timer_offset() * NSEC_PER_USEC;

      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);
      clock_was_set();

      return 0;
}
EXPORT_SYMBOL(do_settimeofday);
#endif /* !CONFIG_GENERIC_TIME */

#ifndef CONFIG_GENERIC_CLOCKEVENTS
/* last time the RTC clock got updated */
static long last_rtc_update;

/*
 * handle_timer_tick() needs to keep up the real-time clock,
 * as well as call the "do_timer()" routine every clocktick
 */
void handle_timer_tick(void)
{
      do_timer(1);
#ifndef CONFIG_SMP
      update_process_times(user_mode(get_irq_regs()));
#endif
      if (current->pid)
            profile_tick(CPU_PROFILING);

#ifdef CONFIG_HEARTBEAT
      if (sh_mv.mv_heartbeat != NULL)
            sh_mv.mv_heartbeat();
#endif

      /*
       * If we have an externally synchronized Linux clock, then update
       * RTC 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 (rtc_sh_set_time(xtime.tv_sec) == 0)
                  last_rtc_update = xtime.tv_sec;
            else
                  /* do it again in 60s */
                  last_rtc_update = xtime.tv_sec - 600;
      }
}
#endif /* !CONFIG_GENERIC_CLOCKEVENTS */

#ifdef CONFIG_PM
int timer_suspend(struct sys_device *dev, pm_message_t state)
{
      struct sys_timer *sys_timer = container_of(dev, struct sys_timer, dev);

      sys_timer->ops->stop();

      return 0;
}

int timer_resume(struct sys_device *dev)
{
      struct sys_timer *sys_timer = container_of(dev, struct sys_timer, dev);

      sys_timer->ops->start();

      return 0;
}
#else
#define timer_suspend NULL
#define timer_resume NULL
#endif

static struct sysdev_class timer_sysclass = {
      set_kset_name("timer"),
      .suspend = timer_suspend,
      .resume      = timer_resume,
};

static int __init timer_init_sysfs(void)
{
      int ret = sysdev_class_register(&timer_sysclass);
      if (ret != 0)
            return ret;

      sys_timer->dev.cls = &timer_sysclass;
      return sysdev_register(&sys_timer->dev);
}
device_initcall(timer_init_sysfs);

void (*board_time_init)(void);

/*
 * Shamelessly based on the MIPS and Sparc64 work.
 */
static unsigned long timer_ticks_per_nsec_quotient __read_mostly;
unsigned long sh_hpt_frequency = 0;

#define NSEC_PER_CYC_SHIFT    10

struct clocksource clocksource_sh = {
      .name       = "SuperH",
      .rating           = 200,
      .mask       = CLOCKSOURCE_MASK(32),
      .read       = null_hpt_read,
      .shift            = 16,
      .flags            = CLOCK_SOURCE_IS_CONTINUOUS,
};

static void __init init_sh_clocksource(void)
{
      if (!sh_hpt_frequency || clocksource_sh.read == null_hpt_read)
            return;

      clocksource_sh.mult = clocksource_hz2mult(sh_hpt_frequency,
                                      clocksource_sh.shift);

      timer_ticks_per_nsec_quotient =
            clocksource_hz2mult(sh_hpt_frequency, NSEC_PER_CYC_SHIFT);

      clocksource_register(&clocksource_sh);
}

#ifdef CONFIG_GENERIC_TIME
unsigned long long sched_clock(void)
{
      unsigned long long ticks = clocksource_sh.read();
      return (ticks * timer_ticks_per_nsec_quotient) >> NSEC_PER_CYC_SHIFT;
}
#endif

void __init time_init(void)
{
      if (board_time_init)
            board_time_init();

      clk_init();

      rtc_sh_get_time(&xtime);
      set_normalized_timespec(&wall_to_monotonic,
                        -xtime.tv_sec, -xtime.tv_nsec);

      /*
       * Find the timer to use as the system timer, it will be
       * initialized for us.
       */
      sys_timer = get_sys_timer();
      printk(KERN_INFO "Using %s for system timer\n", sys_timer->name);

      if (sys_timer->ops->read)
            clocksource_sh.read = sys_timer->ops->read;

      init_sh_clocksource();

      if (sh_hpt_frequency)
            printk("Using %lu.%03lu MHz high precision timer.\n",
                   ((sh_hpt_frequency + 500) / 1000) / 1000,
                   ((sh_hpt_frequency + 500) / 1000) % 1000);

#if defined(CONFIG_SH_KGDB)
      /*
       * Set up kgdb as requested. We do it here because the serial
       * init uses the timer vars we just set up for figuring baud.
       */
      kgdb_init();
#endif
}

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