gem5_to_tlm.cc

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 * Copyright (c) 2016, Dresden University of Technology (TU Dresden)
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 * 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.
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 * 3. Neither the name of the copyright holder 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 HOLDER
 * 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.
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#include "systemc/tlm_bridge/gem5_to_tlm.hh"

#include "params/Gem5ToTlmBridge32.hh"
#include "params/Gem5ToTlmBridge64.hh"
#include "sim/system.hh"
#include "systemc/tlm_bridge/sc_ext.hh"
#include "systemc/tlm_bridge/sc_mm.hh"

namespace sc_gem5
{

Gem5SystemC::MemoryManager mm;

tlm::tlm_generic_payload *
packet2payload(PacketPtr packet)
{
    tlm::tlm_generic_payload *trans = mm.allocate();
    trans->acquire();

    trans->set_address(packet->getAddr());

    /* Check if this transaction was allocated by mm */
    sc_assert(trans->has_mm());

    unsigned int size = packet->getSize();
    unsigned char *data = packet->getPtr<unsigned char>();

    trans->set_data_length(size);
    trans->set_streaming_width(size);
    trans->set_data_ptr(data);

    if ((packet->req->getFlags() & Request::NO_ACCESS) != 0) {
        /* Do nothing */
        trans->set_command(tlm::TLM_IGNORE_COMMAND);
    } else if (packet->isRead()) {
        trans->set_command(tlm::TLM_READ_COMMAND);
    } else if (packet->isWrite()) {
        trans->set_command(tlm::TLM_WRITE_COMMAND);
    } else {
        trans->set_command(tlm::TLM_IGNORE_COMMAND);
    }

    // Attach the packet pointer to the TLM transaction to keep track.
    auto *extension = new Gem5SystemC::Gem5Extension(packet);
    trans->set_auto_extension(extension);

    return trans;
}

template <unsigned int BITWIDTH>
void
Gem5ToTlmBridge<BITWIDTH>::pec(
        tlm::tlm_generic_payload &trans, const tlm::tlm_phase &phase)
{
    sc_core::sc_time delay;

    if (phase == tlm::END_REQ ||
            (&trans == blockingRequest && phase == tlm::BEGIN_RESP)) {
        sc_assert(&trans == blockingRequest);
        blockingRequest = nullptr;

        // Did another request arrive while blocked, schedule a retry.
        if (needToSendRequestRetry) {
            needToSendRequestRetry = false;
            bsp.sendRetryReq();
        }
    }
    if (phase == tlm::BEGIN_RESP) {
        auto &extension = Gem5SystemC::Gem5Extension::getExtension(trans);
        auto packet = extension.getPacket();

        sc_assert(!blockingResponse);

        bool need_retry = false;

        /*
         * If the packet was piped through and needs a response, we don't need
         * to touch the packet and can forward it directly as a response.
         * Otherwise, we need to make a response and send the transformed
         * packet.
         */
        if (extension.isPipeThrough()) {
            if (packet->isResponse()) {
                need_retry = !bsp.sendTimingResp(packet);
            }
        } else if (packet->needsResponse()) {
            packet->makeResponse();
            need_retry = !bsp.sendTimingResp(packet);
        }

        if (need_retry) {
            blockingResponse = &trans;
        } else {
            if (phase == tlm::BEGIN_RESP) {
                // Send END_RESP and we're finished:
                tlm::tlm_phase fw_phase = tlm::END_RESP;
                sc_core::sc_time delay = sc_core::SC_ZERO_TIME;
                socket->nb_transport_fw(trans, fw_phase, delay);
                // Release the transaction with all the extensions.
                trans.release();
            }
        }
    }
}

template <unsigned int BITWIDTH>
MemBackdoorPtr
Gem5ToTlmBridge<BITWIDTH>::getBackdoor(tlm::tlm_generic_payload &trans)
{
    sc_dt::uint64 start = trans.get_address();
    sc_dt::uint64 end = start + trans.get_data_length();

    // Check for a back door we already know about.
    AddrRange r(start, end);
    auto it = backdoorMap.contains(r);
    if (it != backdoorMap.end())
        return it->second;

    // If not, ask the target for one.
    tlm::tlm_dmi dmi_data;
    if (!socket->get_direct_mem_ptr(trans, dmi_data))
        return nullptr;

    // If the target gave us one, translate it to a gem5 MemBackdoor and
    // store it in our cache.
    AddrRange dmi_r(dmi_data.get_start_address(), dmi_data.get_end_address());
    auto backdoor = new MemBackdoor(
            dmi_r, dmi_data.get_dmi_ptr(), MemBackdoor::NoAccess);
    backdoor->readable(dmi_data.is_read_allowed());
    backdoor->writeable(dmi_data.is_write_allowed());

    backdoorMap.insert(dmi_r, backdoor);

    return backdoor;
}

// Similar to TLM's blocking transport (LT)
template <unsigned int BITWIDTH>
Tick
Gem5ToTlmBridge<BITWIDTH>::recvAtomic(PacketPtr packet)
{
    panic_if(packet->cacheResponding(),
             "Should not see packets where cache is responding");

    // Prepare the transaction.
    auto *trans = packet2payload(packet);

    sc_core::sc_time delay = sc_core::SC_ZERO_TIME;

    if (trans->get_command() != tlm::TLM_IGNORE_COMMAND) {
        // Execute b_transport:
        socket->b_transport(*trans, delay);
    }

    if (packet->needsResponse())
        packet->makeResponse();

    trans->release();

    return delay.value();
}

template <unsigned int BITWIDTH>
Tick
Gem5ToTlmBridge<BITWIDTH>::recvAtomicBackdoor(
        PacketPtr packet, MemBackdoorPtr &backdoor)
{
    panic_if(packet->cacheResponding(),
             "Should not see packets where cache is responding");

    sc_core::sc_time delay = sc_core::SC_ZERO_TIME;

    // Prepare the transaction.
    auto *trans = packet2payload(packet);

    if (trans->get_command() != tlm::TLM_IGNORE_COMMAND) {
        // Execute b_transport:
        socket->b_transport(*trans, delay);
        // If the hint said we could use DMI, set that up.
        if (trans->is_dmi_allowed())
            backdoor = getBackdoor(*trans);
    } else {
        // There's no transaction to piggy back on, so just request the
        // backdoor normally.
        backdoor = getBackdoor(*trans);
    }

    if (packet->needsResponse())
        packet->makeResponse();

    trans->release();

    return delay.value();
}

template <unsigned int BITWIDTH>
void
Gem5ToTlmBridge<BITWIDTH>::recvFunctionalSnoop(PacketPtr packet)
{
    // Snooping should be implemented with tlm_dbg_transport.
    SC_REPORT_FATAL("Gem5ToTlmBridge",
            "unimplemented func.: recvFunctionalSnoop");
}

// Similar to TLM's non-blocking transport (AT).
template <unsigned int BITWIDTH>
bool
Gem5ToTlmBridge<BITWIDTH>::recvTimingReq(PacketPtr packet)
{
    panic_if(packet->cacheResponding(),
             "Should not see packets where cache is responding");

    // We should never get a second request after noting that a retry is
    // required.
    sc_assert(!needToSendRequestRetry);

    // Remember if a request comes in while we're blocked so that a retry
    // can be sent to gem5.
    if (blockingRequest) {
        needToSendRequestRetry = true;
        return false;
    }

    /*
     * NOTE: normal tlm is blocking here. But in our case we return false
     * and tell gem5 when a retry can be done. This is the main difference
     * in the protocol:
     * if (requestInProgress)
     * {
     *     wait(endRequestEvent);
     * }
     * requestInProgress = trans;
     */

    // Prepare the transaction.
    auto *trans = packet2payload(packet);

    /*
     * Pay for annotated transport delays.
     *
     * The header delay marks the point in time, when the packet first is seen
     * by the transactor. This is the point in time when the transactor needs
     * to send the BEGIN_REQ to the SystemC world.
     *
     * NOTE: We drop the payload delay here. Normally, the receiver would be
     *       responsible for handling the payload delay. In this case, however,
     *       the receiver is a SystemC module and has no notion of the gem5
     *       transport protocol and we cannot simply forward the
     *       payload delay to the receiving module. Instead, we expect the
     *       receiving SystemC module to model the payload delay by deferring
     *       the END_REQ. This could lead to incorrect delays, if the XBar
     *       payload delay is longer than the time the receiver needs to accept
     *       the request (time between BEGIN_REQ and END_REQ).
     *
     * TODO: We could detect the case described above by remembering the
     *       payload delay and comparing it to the time between BEGIN_REQ and
     *       END_REQ. Then, a warning should be printed.
     */
    auto delay = sc_core::sc_time::from_value(packet->payloadDelay);
    // Reset the delays
    packet->payloadDelay = 0;
    packet->headerDelay = 0;

    // Starting TLM non-blocking sequence (AT) Refer to IEEE1666-2011 SystemC
    // Standard Page 507 for a visualisation of the procedure.
    tlm::tlm_phase phase = tlm::BEGIN_REQ;
    tlm::tlm_sync_enum status;
    status = socket->nb_transport_fw(*trans, phase, delay);
    // Check returned value:
    if (status == tlm::TLM_ACCEPTED) {
        sc_assert(phase == tlm::BEGIN_REQ);
        // Accepted but is now blocking until END_REQ (exclusion rule).
        blockingRequest = trans;
    } else if (status == tlm::TLM_UPDATED) {
        // The Timing annotation must be honored:
        sc_assert(phase == tlm::END_REQ || phase == tlm::BEGIN_RESP);
        auto cb = [this, trans, phase]() { pec(*trans, phase); };
        system->schedule(new EventFunctionWrapper(cb, "pec", true),
                         curTick() + delay.value());
    } else if (status == tlm::TLM_COMPLETED) {
        // Transaction is over nothing has do be done.
        sc_assert(phase == tlm::END_RESP);
        trans->release();
    }

    return true;
}

template <unsigned int BITWIDTH>
bool
Gem5ToTlmBridge<BITWIDTH>::recvTimingSnoopResp(PacketPtr packet)
{
    // Snooping should be implemented with tlm_dbg_transport.
    SC_REPORT_FATAL("Gem5ToTlmBridge",
            "unimplemented func.: recvTimingSnoopResp");
    return false;
}

template <unsigned int BITWIDTH>
bool
Gem5ToTlmBridge<BITWIDTH>::tryTiming(PacketPtr packet)
{
    panic("tryTiming(PacketPtr) isn't implemented.");
}

template <unsigned int BITWIDTH>
void
Gem5ToTlmBridge<BITWIDTH>::recvRespRetry()
{
    /* Retry a response */
    sc_assert(blockingResponse);

    tlm::tlm_generic_payload *trans = blockingResponse;
    blockingResponse = nullptr;
    PacketPtr packet =
        Gem5SystemC::Gem5Extension::getExtension(trans).getPacket();

    bool need_retry = !bsp.sendTimingResp(packet);

    sc_assert(!need_retry);

    sc_core::sc_time delay = sc_core::SC_ZERO_TIME;
    tlm::tlm_phase phase = tlm::END_RESP;
    socket->nb_transport_fw(*trans, phase, delay);
    // Release transaction with all the extensions
    trans->release();
}

// Similar to TLM's debug transport.
template <unsigned int BITWIDTH>
void
Gem5ToTlmBridge<BITWIDTH>::recvFunctional(PacketPtr packet)
{
    // Prepare the transaction.
    auto *trans = packet2payload(packet);

    /* Execute Debug Transport: */
    unsigned int bytes = socket->transport_dbg(*trans);
    if (bytes != trans->get_data_length()) {
        SC_REPORT_FATAL("Gem5ToTlmBridge",
                "debug transport was not completed");
    }

    trans->release();
}

template <unsigned int BITWIDTH>
tlm::tlm_sync_enum
Gem5ToTlmBridge<BITWIDTH>::nb_transport_bw(tlm::tlm_generic_payload &trans,
    tlm::tlm_phase &phase, sc_core::sc_time &delay)
{
    auto cb = [this, &trans, phase]() { pec(trans, phase); };
    system->schedule(new EventFunctionWrapper(cb, "pec", true),
                     curTick() + delay.value());
    return tlm::TLM_ACCEPTED;
}

template <unsigned int BITWIDTH>
void
Gem5ToTlmBridge<BITWIDTH>::invalidate_direct_mem_ptr(
        sc_dt::uint64 start_range, sc_dt::uint64 end_range)
{
    AddrRange r(start_range, end_range);

    for (;;) {
        auto it = backdoorMap.intersects(r);
        if (it == backdoorMap.end())
            break;

        it->second->invalidate();
        delete it->second;
        backdoorMap.erase(it);
    };
}

template <unsigned int BITWIDTH>
Gem5ToTlmBridge<BITWIDTH>::Gem5ToTlmBridge(
        Params *params, const sc_core::sc_module_name &mn) :
    Gem5ToTlmBridgeBase(mn), bsp(std::string(name()) + ".gem5", *this),
    socket("tlm_socket"),
    wrapper(socket, std::string(name()) + ".tlm", InvalidPortID),
    system(params->system), blockingRequest(nullptr),
    needToSendRequestRetry(false), blockingResponse(nullptr),
    addrRanges(params->addr_ranges.begin(), params->addr_ranges.end())
{
}

template <unsigned int BITWIDTH>
::Port &
Gem5ToTlmBridge<BITWIDTH>::gem5_getPort(const std::string &if_name, int idx)
{
    if (if_name == "gem5")
        return bsp;
    else if (if_name == "tlm")
        return wrapper;

    return sc_core::sc_module::gem5_getPort(if_name, idx);
}

template <unsigned int BITWIDTH>
void
Gem5ToTlmBridge<BITWIDTH>::before_end_of_elaboration()
{
    bsp.sendRangeChange();

    socket.register_nb_transport_bw(this, &Gem5ToTlmBridge::nb_transport_bw);
    socket.register_invalidate_direct_mem_ptr(
            this, &Gem5ToTlmBridge::invalidate_direct_mem_ptr);
    sc_core::sc_module::before_end_of_elaboration();
}

} // namespace sc_gem5

sc_gem5::Gem5ToTlmBridge<32> *
Gem5ToTlmBridge32Params::create()
{
    return new sc_gem5::Gem5ToTlmBridge<32>(
            this, sc_core::sc_module_name(name.c_str()));
}

sc_gem5::Gem5ToTlmBridge<64> *
Gem5ToTlmBridge64Params::create()
{
    return new sc_gem5::Gem5ToTlmBridge<64>(
            this, sc_core::sc_module_name(name.c_str()));
}