| /* |
| * Copyright (c) 2011-2012 ARM Limited |
| * All rights reserved |
| * |
| * The license below extends only to copyright in the software and shall |
| * not be construed as granting a license to any other intellectual |
| * property including but not limited to intellectual property relating |
| * to a hardware implementation of the functionality of the software |
| * licensed hereunder. You may use the software subject to the license |
| * terms below provided that you ensure that this notice is replicated |
| * unmodified and in its entirety in all distributions of the software, |
| * modified or unmodified, in source code or in binary form. |
| * |
| * Copyright (c) 2006 The Regents of The University of Michigan |
| * 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 |
| * (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: Ali Saidi |
| * Steve Reinhardt |
| * Andreas Hansson |
| */ |
| |
| /** |
| * @file |
| * Implementation of a memory-mapped bus bridge that connects a master |
| * and a slave through a request and response queue. |
| */ |
| |
| #include "base/trace.hh" |
| #include "debug/BusBridge.hh" |
| #include "mem/bridge.hh" |
| #include "params/Bridge.hh" |
| |
| Bridge::BridgeSlavePort::BridgeSlavePort(const std::string &_name, |
| Bridge* _bridge, |
| BridgeMasterPort& _masterPort, |
| int _delay, int _nack_delay, |
| int _resp_limit, |
| std::vector<Range<Addr> > _ranges) |
| : SlavePort(_name, _bridge), bridge(_bridge), masterPort(_masterPort), |
| delay(_delay), nackDelay(_nack_delay), |
| ranges(_ranges.begin(), _ranges.end()), |
| outstandingResponses(0), inRetry(false), |
| respQueueLimit(_resp_limit), sendEvent(*this) |
| { |
| } |
| |
| Bridge::BridgeMasterPort::BridgeMasterPort(const std::string &_name, |
| Bridge* _bridge, |
| BridgeSlavePort& _slavePort, |
| int _delay, int _req_limit) |
| : MasterPort(_name, _bridge), bridge(_bridge), slavePort(_slavePort), |
| delay(_delay), inRetry(false), reqQueueLimit(_req_limit), |
| sendEvent(*this) |
| { |
| } |
| |
| Bridge::Bridge(Params *p) |
| : MemObject(p), |
| slavePort(p->name + "-slave", this, masterPort, p->delay, |
| p->nack_delay, p->resp_size, p->ranges), |
| masterPort(p->name + "-master", this, slavePort, p->delay, p->req_size), |
| ackWrites(p->write_ack), _params(p) |
| { |
| if (ackWrites) |
| panic("No support for acknowledging writes\n"); |
| } |
| |
| MasterPort& |
| Bridge::getMasterPort(const std::string &if_name, int idx) |
| { |
| if (if_name == "master") |
| return masterPort; |
| else |
| // pass it along to our super class |
| return MemObject::getMasterPort(if_name, idx); |
| } |
| |
| SlavePort& |
| Bridge::getSlavePort(const std::string &if_name, int idx) |
| { |
| if (if_name == "slave") |
| return slavePort; |
| else |
| // pass it along to our super class |
| return MemObject::getSlavePort(if_name, idx); |
| } |
| |
| void |
| Bridge::init() |
| { |
| // make sure both sides are connected and have the same block size |
| if (!slavePort.isConnected() || !masterPort.isConnected()) |
| fatal("Both ports of bus bridge are not connected to a bus.\n"); |
| |
| if (slavePort.peerBlockSize() != masterPort.peerBlockSize()) |
| fatal("Slave port size %d, master port size %d \n " \ |
| "Busses don't have the same block size... Not supported.\n", |
| slavePort.peerBlockSize(), masterPort.peerBlockSize()); |
| |
| // notify the master side of our address ranges |
| slavePort.sendRangeChange(); |
| } |
| |
| bool |
| Bridge::BridgeSlavePort::respQueueFull() |
| { |
| return outstandingResponses == respQueueLimit; |
| } |
| |
| bool |
| Bridge::BridgeMasterPort::reqQueueFull() |
| { |
| return requestQueue.size() == reqQueueLimit; |
| } |
| |
| bool |
| Bridge::BridgeMasterPort::recvTimingResp(PacketPtr pkt) |
| { |
| // all checks are done when the request is accepted on the slave |
| // side, so we are guaranteed to have space for the response |
| DPRINTF(BusBridge, "recvTiming: response %s addr 0x%x\n", |
| pkt->cmdString(), pkt->getAddr()); |
| |
| DPRINTF(BusBridge, "Request queue size: %d\n", requestQueue.size()); |
| |
| slavePort.queueForSendTiming(pkt); |
| |
| return true; |
| } |
| |
| bool |
| Bridge::BridgeSlavePort::recvTimingReq(PacketPtr pkt) |
| { |
| DPRINTF(BusBridge, "recvTiming: request %s addr 0x%x\n", |
| pkt->cmdString(), pkt->getAddr()); |
| |
| DPRINTF(BusBridge, "Response queue size: %d outresp: %d\n", |
| responseQueue.size(), outstandingResponses); |
| |
| if (masterPort.reqQueueFull()) { |
| DPRINTF(BusBridge, "Request queue full, nacking\n"); |
| nackRequest(pkt); |
| return true; |
| } |
| |
| if (pkt->needsResponse()) { |
| if (respQueueFull()) { |
| DPRINTF(BusBridge, |
| "Response queue full, no space for response, nacking\n"); |
| DPRINTF(BusBridge, |
| "queue size: %d outstanding resp: %d\n", |
| responseQueue.size(), outstandingResponses); |
| nackRequest(pkt); |
| return true; |
| } else { |
| DPRINTF(BusBridge, "Request Needs response, reserving space\n"); |
| assert(outstandingResponses != respQueueLimit); |
| ++outstandingResponses; |
| } |
| } |
| |
| masterPort.queueForSendTiming(pkt); |
| |
| return true; |
| } |
| |
| void |
| Bridge::BridgeSlavePort::nackRequest(PacketPtr pkt) |
| { |
| // Nack the packet |
| pkt->makeTimingResponse(); |
| pkt->setNacked(); |
| |
| // The Nack packets are stored in the response queue just like any |
| // other response, but they do not occupy any space as this is |
| // tracked by the outstandingResponses, this guarantees space for |
| // the Nack packets, but implicitly means we have an (unrealistic) |
| // unbounded Nack queue. |
| |
| // put it on the list to send |
| Tick readyTime = curTick() + nackDelay; |
| DeferredResponse resp(pkt, readyTime, true); |
| |
| // nothing on the list, add it and we're done |
| if (responseQueue.empty()) { |
| assert(!sendEvent.scheduled()); |
| bridge->schedule(sendEvent, readyTime); |
| responseQueue.push_back(resp); |
| return; |
| } |
| |
| assert(sendEvent.scheduled() || inRetry); |
| |
| // does it go at the end? |
| if (readyTime >= responseQueue.back().ready) { |
| responseQueue.push_back(resp); |
| return; |
| } |
| |
| // ok, somewhere in the middle, fun |
| std::list<DeferredResponse>::iterator i = responseQueue.begin(); |
| std::list<DeferredResponse>::iterator end = responseQueue.end(); |
| std::list<DeferredResponse>::iterator begin = responseQueue.begin(); |
| bool done = false; |
| |
| while (i != end && !done) { |
| if (readyTime < (*i).ready) { |
| if (i == begin) |
| bridge->reschedule(sendEvent, readyTime); |
| responseQueue.insert(i, resp); |
| done = true; |
| } |
| i++; |
| } |
| assert(done); |
| } |
| |
| void |
| Bridge::BridgeMasterPort::queueForSendTiming(PacketPtr pkt) |
| { |
| Tick readyTime = curTick() + delay; |
| |
| // If we expect to see a response, we need to restore the source |
| // and destination field that is potentially changed by a second |
| // bus |
| if (!pkt->memInhibitAsserted() && pkt->needsResponse()) { |
| // Update the sender state so we can deal with the response |
| // appropriately |
| RequestState *req_state = new RequestState(pkt); |
| pkt->senderState = req_state; |
| } |
| |
| // If we're about to put this packet at the head of the queue, we |
| // need to schedule an event to do the transmit. Otherwise there |
| // should already be an event scheduled for sending the head |
| // packet. |
| if (requestQueue.empty()) { |
| bridge->schedule(sendEvent, readyTime); |
| } |
| |
| assert(requestQueue.size() != reqQueueLimit); |
| |
| requestQueue.push_back(DeferredRequest(pkt, readyTime)); |
| } |
| |
| |
| void |
| Bridge::BridgeSlavePort::queueForSendTiming(PacketPtr pkt) |
| { |
| // This is a response for a request we forwarded earlier. The |
| // corresponding request state should be stored in the packet's |
| // senderState field. |
| RequestState *req_state = dynamic_cast<RequestState*>(pkt->senderState); |
| assert(req_state != NULL); |
| // set up new packet dest & senderState based on values saved |
| // from original request |
| req_state->fixResponse(pkt); |
| |
| // the bridge assumes that at least one bus has set the |
| // destination field of the packet |
| assert(pkt->isDestValid()); |
| DPRINTF(BusBridge, "response, new dest %d\n", pkt->getDest()); |
| delete req_state; |
| |
| Tick readyTime = curTick() + delay; |
| |
| // If we're about to put this packet at the head of the queue, we |
| // need to schedule an event to do the transmit. Otherwise there |
| // should already be an event scheduled for sending the head |
| // packet. |
| if (responseQueue.empty()) { |
| bridge->schedule(sendEvent, readyTime); |
| } |
| responseQueue.push_back(DeferredResponse(pkt, readyTime)); |
| } |
| |
| void |
| Bridge::BridgeMasterPort::trySend() |
| { |
| assert(!requestQueue.empty()); |
| |
| DeferredRequest req = requestQueue.front(); |
| |
| assert(req.ready <= curTick()); |
| |
| PacketPtr pkt = req.pkt; |
| |
| DPRINTF(BusBridge, "trySend request: addr 0x%x\n", pkt->getAddr()); |
| |
| if (sendTimingReq(pkt)) { |
| // send successful |
| requestQueue.pop_front(); |
| |
| // If there are more packets to send, schedule event to try again. |
| if (!requestQueue.empty()) { |
| req = requestQueue.front(); |
| DPRINTF(BusBridge, "Scheduling next send\n"); |
| bridge->schedule(sendEvent, |
| std::max(req.ready, curTick() + 1)); |
| } |
| } else { |
| inRetry = true; |
| } |
| |
| DPRINTF(BusBridge, "trySend: request queue size: %d\n", |
| requestQueue.size()); |
| } |
| |
| void |
| Bridge::BridgeSlavePort::trySend() |
| { |
| assert(!responseQueue.empty()); |
| |
| DeferredResponse resp = responseQueue.front(); |
| |
| assert(resp.ready <= curTick()); |
| |
| PacketPtr pkt = resp.pkt; |
| |
| DPRINTF(BusBridge, "trySend response: dest %d addr 0x%x\n", |
| pkt->getDest(), pkt->getAddr()); |
| |
| bool was_nacked_here = resp.nackedHere; |
| |
| if (sendTimingResp(pkt)) { |
| DPRINTF(BusBridge, " successful\n"); |
| // send successful |
| responseQueue.pop_front(); |
| |
| if (!was_nacked_here) { |
| assert(outstandingResponses != 0); |
| --outstandingResponses; |
| } |
| |
| // If there are more packets to send, schedule event to try again. |
| if (!responseQueue.empty()) { |
| resp = responseQueue.front(); |
| DPRINTF(BusBridge, "Scheduling next send\n"); |
| bridge->schedule(sendEvent, |
| std::max(resp.ready, curTick() + 1)); |
| } |
| } else { |
| DPRINTF(BusBridge, " unsuccessful\n"); |
| inRetry = true; |
| } |
| |
| DPRINTF(BusBridge, "trySend: queue size: %d outstanding resp: %d\n", |
| responseQueue.size(), outstandingResponses); |
| } |
| |
| void |
| Bridge::BridgeMasterPort::recvRetry() |
| { |
| inRetry = false; |
| Tick nextReady = requestQueue.front().ready; |
| if (nextReady <= curTick()) |
| trySend(); |
| else |
| bridge->schedule(sendEvent, nextReady); |
| } |
| |
| void |
| Bridge::BridgeSlavePort::recvRetry() |
| { |
| inRetry = false; |
| Tick nextReady = responseQueue.front().ready; |
| if (nextReady <= curTick()) |
| trySend(); |
| else |
| bridge->schedule(sendEvent, nextReady); |
| } |
| |
| Tick |
| Bridge::BridgeSlavePort::recvAtomic(PacketPtr pkt) |
| { |
| return delay + masterPort.sendAtomic(pkt); |
| } |
| |
| void |
| Bridge::BridgeSlavePort::recvFunctional(PacketPtr pkt) |
| { |
| std::list<DeferredResponse>::iterator i; |
| |
| pkt->pushLabel(name()); |
| |
| // check the response queue |
| for (i = responseQueue.begin(); i != responseQueue.end(); ++i) { |
| if (pkt->checkFunctional((*i).pkt)) { |
| pkt->makeResponse(); |
| return; |
| } |
| } |
| |
| // also check the master port's request queue |
| if (masterPort.checkFunctional(pkt)) { |
| return; |
| } |
| |
| pkt->popLabel(); |
| |
| // fall through if pkt still not satisfied |
| masterPort.sendFunctional(pkt); |
| } |
| |
| bool |
| Bridge::BridgeMasterPort::checkFunctional(PacketPtr pkt) |
| { |
| bool found = false; |
| std::list<DeferredRequest>::iterator i = requestQueue.begin(); |
| |
| while(i != requestQueue.end() && !found) { |
| if (pkt->checkFunctional((*i).pkt)) { |
| pkt->makeResponse(); |
| found = true; |
| } |
| ++i; |
| } |
| |
| return found; |
| } |
| |
| AddrRangeList |
| Bridge::BridgeSlavePort::getAddrRanges() |
| { |
| return ranges; |
| } |
| |
| Bridge * |
| BridgeParams::create() |
| { |
| return new Bridge(this); |
| } |
