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time.c

/*
 * linux/arch/arm/mach-sa1100/time.c
 *
 * Copyright (C) 1998 Deborah Wallach.
 * Twiddles  (C) 1999   Hugo Fiennes <hugo@empeg.com>
 * 
 * 2000/03/29 (C) Nicolas Pitre <nico@cam.org>
 *    Rewritten: big cleanup, much simpler, better HZ accuracy.
 *
 */
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/timex.h>
#include <linux/clockchips.h>

#include <asm/mach/time.h>
#include <mach/hardware.h>

#define MIN_OSCR_DELTA 2

static irqreturn_t sa1100_ost0_interrupt(int irq, void *dev_id)
{
      struct clock_event_device *c = dev_id;

      /* Disarm the compare/match, signal the event. */
      OIER &= ~OIER_E0;
      OSSR = OSSR_M0;
      c->event_handler(c);

      return IRQ_HANDLED;
}

static int
sa1100_osmr0_set_next_event(unsigned long delta, struct clock_event_device *c)
{
      unsigned long flags, next, oscr;

      raw_local_irq_save(flags);
      OIER |= OIER_E0;
      next = OSCR + delta;
      OSMR0 = next;
      oscr = OSCR;
      raw_local_irq_restore(flags);

      return (signed)(next - oscr) <= MIN_OSCR_DELTA ? -ETIME : 0;
}

static void
sa1100_osmr0_set_mode(enum clock_event_mode mode, struct clock_event_device *c)
{
      unsigned long flags;

      switch (mode) {
      case CLOCK_EVT_MODE_ONESHOT:
      case CLOCK_EVT_MODE_UNUSED:
      case CLOCK_EVT_MODE_SHUTDOWN:
            raw_local_irq_save(flags);
            OIER &= ~OIER_E0;
            OSSR = OSSR_M0;
            raw_local_irq_restore(flags);
            break;

      case CLOCK_EVT_MODE_RESUME:
      case CLOCK_EVT_MODE_PERIODIC:
            break;
      }
}

static struct clock_event_device ckevt_sa1100_osmr0 = {
      .name       = "osmr0",
      .features   = CLOCK_EVT_FEAT_ONESHOT,
      .shift            = 32,
      .rating           = 200,
      .cpumask    = CPU_MASK_CPU0,
      .set_next_event   = sa1100_osmr0_set_next_event,
      .set_mode   = sa1100_osmr0_set_mode,
};

static cycle_t sa1100_read_oscr(void)
{
      return OSCR;
}

static struct clocksource cksrc_sa1100_oscr = {
      .name       = "oscr",
      .rating           = 200,
      .read       = sa1100_read_oscr,
      .mask       = CLOCKSOURCE_MASK(32),
      .shift            = 20,
      .flags            = CLOCK_SOURCE_IS_CONTINUOUS,
};

static struct irqaction sa1100_timer_irq = {
      .name       = "ost0",
      .flags            = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
      .handler    = sa1100_ost0_interrupt,
      .dev_id           = &ckevt_sa1100_osmr0,
};

static void __init sa1100_timer_init(void)
{
      OIER = 0;         /* disable any timer interrupts */
      OSSR = 0xf;       /* clear status on all timers */

      ckevt_sa1100_osmr0.mult =
            div_sc(3686400, NSEC_PER_SEC, ckevt_sa1100_osmr0.shift);
      ckevt_sa1100_osmr0.max_delta_ns =
            clockevent_delta2ns(0x7fffffff, &ckevt_sa1100_osmr0);
      ckevt_sa1100_osmr0.min_delta_ns =
            clockevent_delta2ns(MIN_OSCR_DELTA * 2, &ckevt_sa1100_osmr0) + 1;

      cksrc_sa1100_oscr.mult =
            clocksource_hz2mult(CLOCK_TICK_RATE, cksrc_sa1100_oscr.shift);

      setup_irq(IRQ_OST0, &sa1100_timer_irq);

      clocksource_register(&cksrc_sa1100_oscr);
      clockevents_register_device(&ckevt_sa1100_osmr0);
}

#ifdef CONFIG_PM
unsigned long osmr[4], oier;

static void sa1100_timer_suspend(void)
{
      osmr[0] = OSMR0;
      osmr[1] = OSMR1;
      osmr[2] = OSMR2;
      osmr[3] = OSMR3;
      oier = OIER;
}

static void sa1100_timer_resume(void)
{
      OSSR = 0x0f;
      OSMR0 = osmr[0];
      OSMR1 = osmr[1];
      OSMR2 = osmr[2];
      OSMR3 = osmr[3];
      OIER = oier;

      /*
       * OSMR0 is the system timer: make sure OSCR is sufficiently behind
       */
      OSCR = OSMR0 - LATCH;
}
#else
#define sa1100_timer_suspend NULL
#define sa1100_timer_resume NULL
#endif

struct sys_timer sa1100_timer = {
      .init       = sa1100_timer_init,
      .suspend    = sa1100_timer_suspend,
      .resume           = sa1100_timer_resume,
};

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