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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.

 */

/*

 * clock.c - clock driver for i8254.

 */

#include <kernel.h>

#include <timer.h>

#include <irq.h>

#include <sys/ipl.h>

#include <cpufunc.h>

/* Interrupt vector for clock */

#define CLOCK_IRQ        0

/* The internal tick rate in ticks per second */

#define PIT_TICK        1193180L

/* The latch count value for the current HZ setting */

#define PIT_LATCH        ((PIT_TICK + (HZ / 2)) / HZ)

/* I/O port for programmable interval timer */

#define PIT_CH0                0x40

#define PIT_CTRL        0x43

/*

 * Clock interrupt service routine.

 * No H/W reprogram is required.

 */

static int

clock_isr(void *arg)

{

        int s;

        s = splhigh();

        timer_handler();

        splx(s);

        return INT_DONE;

}

/*

 * Initialize clock H/W chip.

 * Setup clock tick rate and install clock ISR.

 */

void

clock_init(void)

{

        irq_t clock_irq;

        outb_p(PIT_CTRL, 0x34);                /* Command to set generator mode */

        outb_p(PIT_CH0, (u_char)(PIT_LATCH & 0xff));                /* LSB */

        outb_p(PIT_CH0, (u_char)((PIT_LATCH >> 8) & 0xff));        /* MSB */

        clock_irq = irq_attach(CLOCK_IRQ, IPL_CLOCK, 0, &clock_isr,

                               IST_NONE, NULL);

        DPRINTF(("Clock rate: %d ticks/sec\n", CONFIG_HZ));

}