Pit.cc

/*
 * Copyright (c) 2008-2014, Pedigree Developers
 *
 * Please see the CONTRIB file in the root of the source tree for a full
 * list of contributors.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include "Pit.h"
#include "pedigree/kernel/compiler.h"
#include "pedigree/kernel/machine/IrqManager.h"
#include "pedigree/kernel/machine/Machine.h"
#include "pedigree/kernel/machine/TimerHandler.h"
#include "pedigree/kernel/processor/types.h"

#ifdef BOCHS
#define PIT_FREQUENCY 10
#else
#define PIT_FREQUENCY 100
#endif

Pit Pit::m_Instance;

bool Pit::registerHandler(TimerHandler *handler)
{
    if (UNLIKELY(handler == 0 && m_Handler != 0))
        return false;

    m_Handler = handler;
    return true;
}

bool Pit::initialise()
{
    // Allocate the PIT I/O range
    if (m_IoPort.allocate(0x40, 4) == false)
        return false;

    // Allocate the IRQ
    IrqManager &irqManager = *Machine::instance().getIrqManager();
    m_IrqId = irqManager.registerIsaIrqHandler(0, this, true);
    if (m_IrqId == 0)
        return false;

    // Set the PIT frequency
    // The value we send to the PIT is the value to divide it's input clock
    // (1193180 Hz) by, to get our required frequency. Important to note is
    // that the divisor must be small enough to fit into 16-bits.
    size_t divisor = 1193180 / PIT_FREQUENCY;

    // Send the command byte.
    m_IoPort.write8(0x36, 3);

    // Divisor has to be sent byte-wise, so split here into upper/lower bytes.
    uint8_t l = divisor & 0xFF;
    uint8_t h = (divisor >> 8) & 0xFF;

    // Send the frequency divisor.
    m_IoPort.write8(l, 0);
    m_IoPort.write8(h, 0);

    return true;
}
void Pit::uninitialise()
{
    // TODO: Reset the PIT frequency

    // Free the IRQ
    if (m_IrqId != 0)
    {
        IrqManager &irqManager = *Machine::instance().getIrqManager();
        irqManager.unregisterHandler(m_IrqId, this);
    }

    // Free the PIT I/O range
    m_IoPort.free();
}

Pit::Pit() : m_IoPort("PIT"), m_IrqId(0), m_Handler(0)
{
}

bool Pit::irq(irq_id_t number, InterruptState &state)
{
    // TODO: Delta is wrong
    if (LIKELY(m_Handler != 0))
        m_Handler->timer(0, state);

    // Processor::information().getScheduler().checkEventState(state.getStackPointer());

    return true;
}