pic.c

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/*
 * Copyright (c) 2014, Michael Müller
 * Copyright (c) 2014, Sebastian Lackner
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT OWNER 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.
 *
 */

#include <hardware/pic.h>
#include <interrupt/interrupt.h>
#include <console/console.h>
#include <util/util.h>
#include <io/io.h>

uint32_t irqBase = 0;

irq_callback irqTable[IRQ_COUNT];

static uint32_t interrupt_irq(uint32_t interrupt, UNUSED uint32_t error, UNUSED struct thread *t)
{
    uint32_t status = INTERRUPT_CONTINUE_EXECUTION;
    uint32_t irq    = interrupt - irqBase;
    assert(irq < IRQ_COUNT);

    /* TODO: handle spurious IRQs */

    /*
     * We should never get irq 2 since it is only used to notify the master PIC
     * about irqs on the slave PIC and the slave IRQs have a higher priority.
     * Since we also send EOI to the master when an IRQ on the slave is
     * signaled, this interrupt should never reach the CPU.
     */
    assert(irq != IRQ_SLAVE);

    if (irqTable[irq])
        status = irqTable[irq](irq);
    else
    {
        consoleWriteString("Unhandled IRQ: ");
        consoleWriteHex32(irq);
        consoleWriteString("\n");
    }

    /* Send EOI */
    if(irq >= 8)
        outb(PIC2_COMMAND_PORT, PIC_EOI);

    outb(PIC1_COMMAND_PORT, PIC_EOI);

    return status;
}

void picInit(uint32_t interruptOffset)
{
    uint32_t i;

    /* the offset must be a multiple of 8 */
    assert((interruptOffset & 7) == 0);
    irqBase = interruptOffset;

    /* Initialize in Cascade mode */
    outb(PIC1_COMMAND_PORT, ICW1_INIT+ICW1_ICW4);
    outb(PIC1_COMMAND_PORT, ICW1_INIT+ICW1_ICW4);

    outb(PIC1_DATA_PORT, interruptOffset);
    outb(PIC2_DATA_PORT, interruptOffset + 8);

    outb(PIC1_DATA_PORT, 4);
    outb(PIC2_DATA_PORT, 2);

    outb(PIC1_DATA_PORT, ICW4_8086);
    outb(PIC2_DATA_PORT, ICW4_8086);

    /*
     *  Disable all IRQs except the slave IRQ, it won't signal until we enable
     *  an IRQ on the slave chip.
     */
    outb(PIC1_DATA_PORT, 0xF & (~IRQ_SLAVE));
    outb(PIC2_DATA_PORT, 0xF);

    /* reset the irqTable */
    for (i = 0; i < IRQ_COUNT; i++)
        irqTable[i] = NULL;

    /* reserve all 16 interrupts which are now connected to an IRQ */
    for (i = 0; i < IRQ_COUNT; i++)
        assert(interruptReserve(interruptOffset + i, interrupt_irq));
}

bool picReserveIRQ(uint32_t irq, irq_callback callback)
{
    uint16_t port;
    uint8_t mask;

    assert(irq < IRQ_COUNT);
    if (irqTable[irq])
        return false;

    assert(irq != IRQ_SLAVE);
    irqTable[irq] = callback;

    /* actually unmask the irq on the PIC */
    if(irq < 8)
    {
        port = PIC1_DATA_PORT;
    }
    else
    {
        port = PIC2_DATA_PORT;
        irq -= 8;
    }

    mask = inb(port);
    mask &= ~(1 << irq);
    outb(port, mask);

    return true;
}
void picFreeIRQ(uint32_t irq)
{
    uint16_t port;
    uint8_t mask;

    assert(irq < IRQ_COUNT);
    if (!irqTable[irq])
        return;

    assert(irq != IRQ_SLAVE);
    irqTable[irq] = NULL;

    if(irq < 8)
    {
        port = PIC1_DATA_PORT;
    }
    else
    {
        port = PIC2_DATA_PORT;
        irq -= 8;
    }

    mask = inb(port);
    mask |= 1 << irq;
    outb(port, mask);
}