src/systemc/tlm_bridge/gem5_to_tlm.cc - public/gem5 - Git at Google

 /*
  * Copyright 2019 Google, Inc.
  *
  * 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
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  * Copyright (c) 2015, University of Kaiserslautern
  * Copyright (c) 2016, Dresden University of Technology (TU Dresden)
  * 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.
  *
  * 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.
  *
  * Authors: Gabe Black
  *          Matthias Jung
  *          Abdul Mutaal Ahmad
  *          Christian Menard
  */

 #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
 {

 /**
  * Instantiate a tlm memory manager that takes care about all the
  * tlm transactions in the system.
  */
 Gem5SystemC::MemoryManager mm;

 /**
  * Convert a gem5 packet to a TLM payload by copying all the relevant
  * information to new tlm payload.
  */
 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->isInvalidate()) {
         /* Do nothing */
         trans->set_command(tlm::TLM_IGNORE_COMMAND);
     } else if (packet->isWrite()) {
         trans->set_command(tlm::TLM_WRITE_COMMAND);
     } else {
         SC_REPORT_FATAL("Gem5ToTlmBridge", "No R/W packet");
     }

     // 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(
         Gem5SystemC::PayloadEvent<Gem5ToTlmBridge<BITWIDTH>> *pe,
         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();
             }
         }
     }
     delete pe;
 }

 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");

     panic_if(!(packet->isRead() || packet->isWrite()),
              "Should only see read and writes at TLM memory\n");


     // 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 *pe = new Gem5SystemC::PayloadEvent<Gem5ToTlmBridge>(
                 *this, &Gem5ToTlmBridge::pec, "PEQ");
         Tick nextEventTick = curTick() + delay.value();
         system->wakeupEventQueue(nextEventTick);
         system->schedule(pe, nextEventTick);
     } 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 *pe = new Gem5SystemC::PayloadEvent<Gem5ToTlmBridge>(
             *this, &Gem5ToTlmBridge::pec, "PE");
     Tick nextEventTick = curTick() + delay.value();
     system->wakeupEventQueue(nextEventTick);
     system->schedule(pe, nextEventTick);
     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()));
 }
	/*
	* Copyright 2019 Google, Inc.
	*
	* 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
	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
	* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	*
	* Copyright (c) 2015, University of Kaiserslautern
	* Copyright (c) 2016, Dresden University of Technology (TU Dresden)
	* 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.
	*
	* 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.
	*
	* Authors: Gabe Black
	* Matthias Jung
	* Abdul Mutaal Ahmad
	* Christian Menard
	*/

	#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
	{

	/**
	* Instantiate a tlm memory manager that takes care about all the
	* tlm transactions in the system.
	*/
	Gem5SystemC::MemoryManager mm;

	/**
	* Convert a gem5 packet to a TLM payload by copying all the relevant
	* information to new tlm payload.
	*/
	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->isInvalidate()) {
	/* Do nothing */
	trans->set_command(tlm::TLM_IGNORE_COMMAND);
	} else if (packet->isWrite()) {
	trans->set_command(tlm::TLM_WRITE_COMMAND);
	} else {
	SC_REPORT_FATAL("Gem5ToTlmBridge", "No R/W packet");
	}

	// 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(
	Gem5SystemC::PayloadEvent<Gem5ToTlmBridge<BITWIDTH>> *pe,
	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();
	}
	}
	}
	delete pe;
	}

	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");

	panic_if(!(packet->isRead() \|\| packet->isWrite()),
	"Should only see read and writes at TLM memory\n");


	// 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 *pe = new Gem5SystemC::PayloadEvent<Gem5ToTlmBridge>(
	*this, &Gem5ToTlmBridge::pec, "PEQ");
	Tick nextEventTick = curTick() + delay.value();
	system->wakeupEventQueue(nextEventTick);
	system->schedule(pe, nextEventTick);
	} 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 *pe = new Gem5SystemC::PayloadEvent<Gem5ToTlmBridge>(
	*this, &Gem5ToTlmBridge::pec, "PE");
	Tick nextEventTick = curTick() + delay.value();
	system->wakeupEventQueue(nextEventTick);
	system->schedule(pe, nextEventTick);
	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()));
	}