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/*

 * linux/include/asm-arm/arch-sa1100/time.h

 *

 * 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.

 *

 */

#define RTC_DEF_DIVIDER         (32768 - 1)

#define RTC_DEF_TRIM            0

static unsigned long __init sa1100_get_rtc_time(void)

{

        /*

         * According to the manual we should be able to let RTTR be zero

         * and then a default diviser for a 32.768KHz clock is used.

         * Apparently this doesn't work, at least for my SA1110 rev 5.

         * If the clock divider is uninitialized then reset it to the

         * default value to get the 1Hz clock.

         */

        if (RTTR == 0) {

                RTTR = RTC_DEF_DIVIDER + (RTC_DEF_TRIM << 16);

                printk(KERN_WARNING "Warning: uninitialized Real Time Clock\n");

                /* The current RTC value probably doesn't make sense either */

                RCNR = 0;

                return 0;

        }

        return RCNR;

}

static int sa1100_set_rtc(void)

{

        unsigned long current_time = xtime.tv_sec;

        if (RTSR & RTSR_ALE) {

                /* make sure not to forward the clock over an alarm */

                unsigned long alarm = RTAR;

                if (current_time >= alarm && alarm >= RCNR)

                        return -ERESTARTSYS;

        }

        RCNR = current_time;

        return 0;

}

/* IRQs are disabled before entering here from do_gettimeofday() */

static unsigned long sa1100_gettimeoffset (void)

{

        unsigned long ticks_to_match, elapsed, usec;

        /* Get ticks before next timer match */

        ticks_to_match = OSMR0 - OSCR;

        /* We need elapsed ticks since last match */

        elapsed = LATCH - ticks_to_match;

        /* Now convert them to usec */

        usec = (unsigned long)(elapsed*tick)/LATCH;

        return usec;

}

static void sa1100_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)

{

        unsigned int next_match;

        unsigned long flags;

        do {

                do_leds();

                local_irq_save(flags);

                do_timer(regs);

                OSSR = OSSR_M0;  /* Clear match on timer 0 */

                next_match = (OSMR0 += LATCH);

                local_irq_restore(flags);

                do_set_rtc();

        } while ((signed long)(next_match - OSCR) <= 0);

        do_profile(regs);

}

static inline void setup_timer (void)

{

        gettimeoffset = sa1100_gettimeoffset;

        set_rtc = sa1100_set_rtc;

        xtime.tv_sec = sa1100_get_rtc_time();

        timer_irq.handler = sa1100_timer_interrupt;

        OSMR0 = 0;               /* set initial match at 0 */

        OSSR = 0xf;             /* clear status on all timers */

        setup_arm_irq(IRQ_OST0, &timer_irq);

        OIER |= OIER_E0;        /* enable match on timer 0 to cause interrupts */

        OSCR = 0;                /* initialize free-running timer, force first match */

}