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 * Copyright (c) 2021 Huawei International
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 * to a hardware implementation of the functionality of the software
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 * met: redistributions of source code must retain the above copyright
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#include "dev/riscv/clint.hh"

#include "debug/Clint.hh"
#include "mem/packet.hh"
#include "mem/packet_access.hh"
#include "params/Clint.hh"
#include "sim/system.hh"

using namespace RiscvISA;

Clint::Clint(const Params &params) :
    BasicPioDevice(params, params.pio_size),
    system(params.system),
    intrctrl(params.intrctrl),
    signal(params.name + ".signal", 0, this),
    registers(params.name + ".registers", params.pio_addr, this)
{
}

void
Clint::raiseInterruptPin(int id)
{
    // Increment mtime
    uint64_t& mtime = registers.mtime.get();
    mtime++;

    for (int context_id = 0; context_id < nThread; context_id++) {

        // Update misc reg file
        system->threads[context_id]->setMiscRegNoEffect(MISCREG_TIME, mtime);

        // Post timer interrupt
        uint64_t mtimecmp = registers.mtimecmp[context_id].get();
        if (mtime >= mtimecmp) {
                if (mtime == mtimecmp) {
                    DPRINTF(Clint,
                        "MTIP posted - thread: %d, mtime: %d, mtimecmp: %d\n",
                        context_id, mtime, mtimecmp);
                }
            intrctrl->post(context_id, ExceptionCode::INT_TIMER_MACHINE, 0);
        } else {
            intrctrl->clear(context_id, ExceptionCode::INT_TIMER_MACHINE, 0);
        }
    }
}

void
Clint::ClintRegisters::init()
{
    using namespace std::placeholders;

    // Calculate reserved space size
    const size_t reserved0_size = mtimecmpStart - clint->nThread * 4;
    reserved.emplace_back("reserved0", reserved0_size);
    const size_t reserved1_size = mtimeStart
        - mtimecmpStart - clint->nThread * 8;
    reserved.emplace_back("reserved1", reserved1_size);

    // Sanity check
    assert((int) clint->pioSize <= maxBankSize);

    // Initialize registers
    for (int i = 0; i < clint->nThread; i++) {
        msip.emplace_back(std::string("msip") + std::to_string(i), 0);
        mtimecmp.emplace_back(std::string("mtimecmp") + std::to_string(i), 0);
    }

    // Add registers to bank
    for (int i = 0; i < clint->nThread; i++) {
        auto read_cb = std::bind(&Clint::readMSIP, clint, _1, i);
        msip[i].reader(read_cb);
        auto write_cb = std::bind(&Clint::writeMSIP, clint, _1, _2, i);
        msip[i].writer(write_cb);
        addRegister(msip[i]);
    }
    addRegister(reserved[0]);
    for (int i = 0; i < clint->nThread; i++) {
        addRegister(mtimecmp[i]);
    }
    addRegister(reserved[1]);
    mtime.readonly();
    addRegister(mtime);
}

uint32_t
Clint::readMSIP(Register32& reg, const int thread_id)
{
    // To avoid discrepancies if mip is externally set using remote_gdb etc.
    auto tc = system->threads[thread_id];
    RegVal mip = tc->readMiscReg(MISCREG_IP);
    uint32_t msip = bits<uint32_t>(mip, ExceptionCode::INT_SOFTWARE_MACHINE);
    reg.update(msip);
    return reg.get();
};

void
Clint::writeMSIP(Register32& reg, const uint32_t& data, const int thread_id)
{
    reg.update(data);
    assert(data <= 1);
    if (data > 0) {
        DPRINTF(Clint,
            "MSIP posted - thread: %d\n", thread_id);
        intrctrl->post(thread_id,
            ExceptionCode::INT_SOFTWARE_MACHINE, 0);
    } else {
        DPRINTF(Clint,
            "MSIP cleared - thread: %d\n", thread_id);
        intrctrl->clear(thread_id,
            ExceptionCode::INT_SOFTWARE_MACHINE, 0);
    }
};

Tick
Clint::read(PacketPtr pkt)
{
    // Check for atomic operation
    bool is_atomic = pkt->isAtomicOp() && pkt->cmd == MemCmd::SwapReq;
    DPRINTF(Clint,
        "Read request - addr: %#x, size: %#x, atomic:%d\n",
        pkt->getAddr(), pkt->getSize(), is_atomic);

    // Perform register read
    registers.read(pkt->getAddr(), pkt->getPtr<void>(), pkt->getSize());

    if (is_atomic) {
        // Perform atomic operation
        (*(pkt->getAtomicOp()))(pkt->getPtr<uint8_t>());
        return write(pkt);
    } else {
        pkt->makeResponse();
        return pioDelay;
    }
}

Tick
Clint::write(PacketPtr pkt)
{
    DPRINTF(Clint,
        "Write request - addr: %#x, size: %#x\n",
        pkt->getAddr(), pkt->getSize());

    // Perform register write
    registers.write(pkt->getAddr(), pkt->getPtr<void>(), pkt->getSize());

    pkt->makeResponse();
    return pioDelay;
}

void
Clint::init()
{
    nThread = system->threads.size();
    registers.init();
    BasicPioDevice::init();
}

Port &
Clint::getPort(const std::string &if_name, PortID idx)
{
    if (if_name == "int_pin")
        return signal;
    else
        return BasicPioDevice::getPort(if_name, idx);
}

void
Clint::serialize(CheckpointOut &cp) const
{
    for (auto const &reg: registers.msip) {
        paramOut(cp, reg.name(), reg);
    }
    for (auto const &reg: registers.mtimecmp) {
        paramOut(cp, reg.name(), reg);
    }
    paramOut(cp, "mtime", registers.mtime);
}

void
Clint::unserialize(CheckpointIn &cp)
{
    for (auto &reg: registers.msip) {
        paramIn(cp, reg.name(), reg);
    }
    for (auto &reg: registers.mtimecmp) {
        paramIn(cp, reg.name(), reg);
    }
    paramIn(cp, "mtime", registers.mtime);
}