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/*-

 * Copyright (c) 2005-2007, Kohsuke Ohtani

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. Neither the name of the author nor the names of any co-contributors

 *    may be used to endorse or promote products derived from this software

 *    without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND

 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE

 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL

 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS

 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)

 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY

 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF

 * SUCH DAMAGE.

 */

/*

 * delay.c - driver delay routine

 */

#include <driver.h>

#ifdef DEBUG

#define DPRINTF(a) printf a

#else

#define DPRINTF(a)

#endif

static u_long delay_count;        /* Loop count for 1ms */

static

void delay_loop(u_long count)

{

        volatile u_long i;

        for (i = 0; i < count; i++);

}

/*

 * Delay micro seconds (non-blocking)

 * timer_udelay() can be called from ISR at interrupt level.

 */

void

delay_usec(u_long usec)

{

        delay_loop(delay_count * usec / 1000);

}

/*

 * Compute the loop count for 1ms.

 * Assumes clock interrupt is enabled.

 */

void

calibrate_delay(void)

{

        u_long ticks, test_bit;

        DPRINTF(("Calibrating delay loop... "));

        delay_count = 1;

        for (;;) {

                delay_count <<= 1;

                ticks = timer_ticks();

                while (ticks == timer_ticks());

                ticks = timer_ticks();

                delay_loop(delay_count);

                if (ticks != timer_ticks())

                        break;

        }

        delay_count >>= 1;

        test_bit = delay_count;

        for (;;) {

                test_bit >>= 1;

                if (test_bit == 0)

                        break;

                delay_count |= test_bit;

                ticks = timer_ticks();

                while (ticks == timer_ticks());

                ticks = timer_ticks();

                delay_loop(delay_count);

                if (ticks != timer_ticks())

                        delay_count &= ~test_bit;

        }

        delay_count *= 1000;        /* count per 1sec */

        delay_count /= 1000;        /* count per 1ms */

        DPRINTF(("ok count=%ld\n", delay_count));

}