/*
 * Copyright 2008, Dustin Howett, dustin.howett@gmail.com. All rights reserved.
 * Copyright 2005, Axel Dörfler, axeld@pinc-software.de. All rights reserved.
 * Distributed under the terms of the MIT License.
 *
 * Copyright 2001, Travis Geiselbrecht. All rights reserved.
 * Distributed under the terms of the NewOS License.
 */

#include <timer.h>
#include <arch/x86/timer.h>

#include <arch/int.h>
#include <arch/cpu.h>

#include "pit.h"


//#define TRACE_PIT
#ifdef TRACE_PIT
#       define TRACE(x...) dprintf("pit: " x)
#else
#       define TRACE(x...) ;
#endif


static bool sPITTimerInitialized = false;

struct timer_info gPITTimer = {
        "PIT",
        &pit_get_prio,
        &pit_set_hardware_timer,
        &pit_clear_hardware_timer,
        &pit_init
};


static int
pit_get_prio(void)
{
        return 1;
}


static int32
pit_timer_interrupt(void *data)
{
        return timer_interrupt();
}


static status_t
pit_set_hardware_timer(bigtime_t relativeTimeout)
{
        uint16 nextEventClocks;

        if (relativeTimeout <= 0)
                nextEventClocks = 2;
        else if (relativeTimeout < PIT_MAX_TIMER_INTERVAL)
                nextEventClocks = relativeTimeout * PIT_CLOCK_RATE / 1000000;
        else
                nextEventClocks = 0xffff;

        out8(PIT_SELCH0 | PIT_RWBOTH | PIT_MD_INTON0, PIT_CTRL);
        out8(nextEventClocks & 0xff, PIT_CNT0);
        out8((nextEventClocks >> 8) & 0xff, PIT_CNT0);

        arch_int_enable_io_interrupt(0);
        return B_OK;
}


static status_t
pit_clear_hardware_timer(void)
{
        arch_int_disable_io_interrupt(0);
        return B_OK;
}


static status_t
pit_init(struct kernel_args *args)
{
        if (sPITTimerInitialized) {
                TRACE("timer is already initialized");
                return B_OK;
        }

        install_io_interrupt_handler(0, &pit_timer_interrupt, NULL, 0);
        pit_clear_hardware_timer();

        sPITTimerInitialized = true;
        TRACE("timer initialized");

        return B_OK;
}