interrupt.c

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/*
 * Copyright (C) 2003-2004 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - 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.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
 */

#include <interrupt.h>
#include <arch/interrupt.h>
#include <arch/types.h>
#include <arch.h>
#include <arch/cp0.h>
#include <time/clock.h>
#include <arch/drivers/arc.h>

#include <ipc/sysipc.h>

ipl_t interrupts_disable(void)
{
        ipl_t ipl = (ipl_t) cp0_status_read();
        cp0_status_write(ipl & ~cp0_status_ie_enabled_bit);
        return ipl;
}

ipl_t interrupts_enable(void)
{
        ipl_t ipl = (ipl_t) cp0_status_read();
        cp0_status_write(ipl | cp0_status_ie_enabled_bit);
        return ipl;
}

void interrupts_restore(ipl_t ipl)
{
        cp0_status_write(cp0_status_read() | (ipl & cp0_status_ie_enabled_bit));
}

ipl_t interrupts_read(void)
{
        return cp0_status_read();
}

/* TODO: This is SMP unsafe!!! */
static unsigned long nextcount;
static void timer_start(void)
{
        nextcount = cp0_compare_value + cp0_count_read();
        cp0_compare_write(nextcount);
}

static void timer_exception(int n, istate_t *istate)
{
        unsigned long drift;

        drift = cp0_count_read() - nextcount;
        while (drift > cp0_compare_value) {
                drift -= cp0_compare_value;
                CPU->missed_clock_ticks++;
        }
        nextcount = cp0_count_read() + cp0_compare_value - drift;
        cp0_compare_write(nextcount);
        clock();
}

static void swint0(int n, istate_t *istate)
{
        cp0_cause_write(cp0_cause_read() & ~(1 << 8)); /* clear SW0 interrupt */
        ipc_irq_send_notif(0);
}

static void swint1(int n, istate_t *istate)
{
        cp0_cause_write(cp0_cause_read() & ~(1 << 9)); /* clear SW1 interrupt */
        ipc_irq_send_notif(1);
}

/* Initialize basic tables for exception dispatching */
void interrupt_init(void)
{
        int_register(TIMER_IRQ, "timer", timer_exception);
        int_register(0, "swint0", swint0);
        int_register(1, "swint1", swint1);
        timer_start();
}

static void ipc_int(int n, istate_t *istate)
{
        ipc_irq_send_notif(n-INT_OFFSET);
}

/* Reregister irq to be IPC-ready */
void irq_ipc_bind_arch(__native irq)
{
        /* Do not allow to redefine timer */
        /* Swint0, Swint1 are already handled */
        if (irq == TIMER_IRQ || irq < 2)
                return;
        int_register(irq, "ipc_int", ipc_int);
}

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