src/dev/lupio/lupio_tmr.cc

/*
 * Copyright (c) 2021 The Regents of the University of California
 * 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;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * 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
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "dev/lupio/lupio_tmr.hh"

#include "cpu/base.hh"
#include "debug/LupioTMR.hh"
#include "mem/packet_access.hh"
#include "params/LupioTMR.hh"

// Specific fields for CTRL
#define LUPIO_TMR_IE    0x1
#define LUPIO_TMR_PD    0x2

// Specific fields for STAT
#define LUPIO_TMR_EX    0x1

namespace gem5
{

LupioTMR::LupioTMR(const Params &params) :
    BasicPioDevice(params, params.pio_size),
    system(params.system),
    nThread(params.num_threads),
    tmrEvent([this]{ lupioTMRCallback(); }, name()),
    intType(params.int_type)
{
    DPRINTF(LupioTMR, "LupioTMR initalized\n");
}

void
LupioTMR::updateIRQ(int level)
{
    if (nThread > 1) {
        panic("This device currently does not offer SMP support\n");
    }

    auto tc = system->threads[0];
    // post an interrupt
    if (level) {
        tc->getCpuPtr()->postInterrupt(tc->threadId(), intType, 0);
    }
    // clear the interrupt
    else {
        tc->getCpuPtr()->clearInterrupt(tc->threadId(), intType, 0);
    }
}

uint64_t
LupioTMR::lupioTMRCurrentTime()
{
    return curTick() / sim_clock::as_int::ns;
}

void
LupioTMR::lupioTMRSet()
{
    startTime = curTick();
    if (!tmrEvent.scheduled()) {
        schedule(tmrEvent, (reload * sim_clock::as_int::ns) + curTick());
    }
}

void
LupioTMR::lupioTMRCallback()
{
    // Signal expiration
    expired = true;
    if (ie) {
        updateIRQ(1);
    }

    // If periodic timer, reload
    if (pd && reload) {
        lupioTMRSet();
    }
}

uint64_t
LupioTMR::lupioTMRRead(uint8_t addr, int size)
{
    uint64_t r = 0;

    switch (addr >> 2) {
        case LUPIO_TMR_TIME:
            r = lupioTMRCurrentTime();
            DPRINTF(LupioTMR, "Read LUPIO_TMR_TME: %d\n", r);
            break;
        case LUPIO_TMR_LOAD:
            r = reload;
            DPRINTF(LupioTMR, "Read LUPIO_TMR_LOAD: %d\n", r);
            break;
        case LUPIO_TMR_STAT:
            if (expired) {
                r |= LUPIO_TMR_EX;
            }

            // Acknowledge expiration
            expired = false;
            DPRINTF(LupioTMR, "Read LUPIO_TMR_STAT: %d\n", r);
            updateIRQ(0);
            break;

        default:
            panic("Unexpected read to the LupioTMR device at address %#llx!",
                    addr);
            break;
    }
    return r;
}

void
LupioTMR::lupioTMRWrite(uint8_t addr, uint64_t val64, int size)
{
    uint32_t val = val64;

    switch (addr >> 2) {
        case LUPIO_TMR_LOAD:
            reload = val;
            DPRINTF(LupioTMR, "Write LUPIO_TMR_LOAD: %d\n", reload);
            break;

        case LUPIO_TMR_CTRL:
                    ie = val & LUPIO_TMR_IE;
                    pd = val & LUPIO_TMR_PD;
            DPRINTF(LupioTMR, "Write LUPIO_TMR_CTRL\n");

            // Stop current timer if any
            if (curTick() < startTime + (reload * sim_clock::as_int::ns)
                && tmrEvent.scheduled()) {
                deschedule(tmrEvent);
            }

            // If reload isn't 0, start a new one
            if (reload) {
                lupioTMRSet();
            }
            break;

        default:
            panic("Unexpected write to the LupioTMR device at address %#llx!",
                    addr);
            break;
    }
}

Tick
LupioTMR::read(PacketPtr pkt)
{
    Addr tmr_addr = pkt->getAddr() - pioAddr;

    DPRINTF(LupioTMR,
        "Read request - addr: %#x, size: %#x\n", tmr_addr, pkt->getSize());

    uint64_t read_val = lupioTMRRead(tmr_addr, pkt->getSize());
    DPRINTF(LupioTMR, "Packet Read: %#x\n", read_val);
    pkt->setUintX(read_val, byteOrder);
    pkt->makeResponse();

    return pioDelay;
}

Tick
LupioTMR::write(PacketPtr pkt)
{
    Addr tmr_addr = pkt->getAddr() - pioAddr;

    DPRINTF(LupioTMR, "Write register %#x value %#x\n", tmr_addr,
            pkt->getUintX(byteOrder));

    lupioTMRWrite(tmr_addr, pkt->getUintX(byteOrder), pkt->getSize());
    DPRINTF(LupioTMR, "Packet Write Value: %d\n", pkt->getUintX(byteOrder));

    pkt->makeResponse();

    return pioDelay;
}
} // namespace gem5