/*
- * Copyright (c) 2011-2012 ARM Limited
+ * Copyright (c) 2011-2013 ARM Limited
* All rights reserved
*
* The license below extends only to copyright in the software and shall
/**
* @file
- * Implementation of a memory-mapped bus bridge that connects a master
+ * Implementation of a memory-mapped bridge that connects a master
* and a slave through a request and response queue.
*/
#include "base/trace.hh"
-#include "debug/BusBridge.hh"
+#include "debug/Bridge.hh"
#include "mem/bridge.hh"
#include "params/Bridge.hh"
-Bridge::BridgeSlavePort::BridgeSlavePort(const std::string &_name,
- Bridge* _bridge,
+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),
+ Cycles _delay, int _resp_limit,
+ std::vector<AddrRange> _ranges)
+ : SlavePort(_name, &_bridge), bridge(_bridge), masterPort(_masterPort),
+ delay(_delay), ranges(_ranges.begin(), _ranges.end()),
+ outstandingResponses(0), retryReq(false),
respQueueLimit(_resp_limit), sendEvent(*this)
{
}
-Bridge::BridgeMasterPort::BridgeMasterPort(const std::string &_name,
- Bridge* _bridge,
+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)
+ Cycles _delay, int _req_limit)
+ : MasterPort(_name, &_bridge), bridge(_bridge), slavePort(_slavePort),
+ delay(_delay), 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)
+ slavePort(p->name + ".slave", *this, masterPort,
+ ticksToCycles(p->delay), p->resp_size, p->ranges),
+ masterPort(p->name + ".master", *this, slavePort,
+ ticksToCycles(p->delay), p->req_size)
{
- if (ackWrites)
- panic("No support for acknowledging writes\n");
}
-MasterPort&
-Bridge::getMasterPort(const std::string &if_name, int idx)
+BaseMasterPort&
+Bridge::getMasterPort(const std::string &if_name, PortID idx)
{
if (if_name == "master")
return masterPort;
return MemObject::getMasterPort(if_name, idx);
}
-SlavePort&
-Bridge::getSlavePort(const std::string &if_name, int idx)
+BaseSlavePort&
+Bridge::getSlavePort(const std::string &if_name, PortID idx)
{
if (if_name == "slave")
return slavePort;
{
// 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());
+ fatal("Both ports of a bridge must be connected.\n");
// notify the master side of our address ranges
slavePort.sendRangeChange();
}
bool
-Bridge::BridgeSlavePort::respQueueFull()
+Bridge::BridgeSlavePort::respQueueFull() const
{
return outstandingResponses == respQueueLimit;
}
bool
-Bridge::BridgeMasterPort::reqQueueFull()
+Bridge::BridgeMasterPort::reqQueueFull() const
{
- return requestQueue.size() == reqQueueLimit;
+ return transmitList.size() == reqQueueLimit;
}
bool
{
// 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",
+ DPRINTF(Bridge, "recvTimingResp: %s addr 0x%x\n",
pkt->cmdString(), pkt->getAddr());
- DPRINTF(BusBridge, "Request queue size: %d\n", requestQueue.size());
+ DPRINTF(Bridge, "Request queue size: %d\n", transmitList.size());
+
+ // @todo: We need to pay for this and not just zero it out
+ pkt->headerDelay = pkt->payloadDelay = 0;
- slavePort.queueForSendTiming(pkt);
+ slavePort.schedTimingResp(pkt, bridge.clockEdge(delay));
return true;
}
bool
Bridge::BridgeSlavePort::recvTimingReq(PacketPtr pkt)
{
- DPRINTF(BusBridge, "recvTiming: request %s addr 0x%x\n",
+ DPRINTF(Bridge, "recvTimingReq: %s addr 0x%x\n",
pkt->cmdString(), pkt->getAddr());
- DPRINTF(BusBridge, "Response queue size: %d outresp: %d\n",
- responseQueue.size(), outstandingResponses);
+ // we should not see a timing request if we are already in a retry
+ assert(!retryReq);
+ DPRINTF(Bridge, "Response queue size: %d outresp: %d\n",
+ transmitList.size(), outstandingResponses);
+
+ // if the request queue is full then there is no hope
if (masterPort.reqQueueFull()) {
- DPRINTF(BusBridge, "Request queue full, nacking\n");
- nackRequest(pkt);
- return true;
- }
+ DPRINTF(Bridge, "Request queue full\n");
+ retryReq = true;
+ } else {
+ // look at the response queue if we expect to see a response
+ bool expects_response = pkt->needsResponse() &&
+ !pkt->memInhibitAsserted();
+ if (expects_response) {
+ if (respQueueFull()) {
+ DPRINTF(Bridge, "Response queue full\n");
+ retryReq = true;
+ } else {
+ // ok to send the request with space for the response
+ DPRINTF(Bridge, "Reserving space for response\n");
+ assert(outstandingResponses != respQueueLimit);
+ ++outstandingResponses;
+
+ // no need to set retryReq to false as this is already the
+ // case
+ }
+ }
- 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;
+ if (!retryReq) {
+ // @todo: We need to pay for this and not just zero it out
+ pkt->headerDelay = pkt->payloadDelay = 0;
+
+ masterPort.schedTimingReq(pkt, bridge.clockEdge(delay));
}
}
- masterPort.queueForSendTiming(pkt);
-
- return true;
+ // remember that we are now stalling a packet and that we have to
+ // tell the sending master to retry once space becomes available,
+ // we make no distinction whether the stalling is due to the
+ // request queue or response queue being full
+ return !retryReq;
}
void
-Bridge::BridgeSlavePort::nackRequest(PacketPtr pkt)
+Bridge::BridgeSlavePort::retryStalledReq()
{
- // 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;
+ if (retryReq) {
+ DPRINTF(Bridge, "Request waiting for retry, now retrying\n");
+ retryReq = false;
+ sendRetry();
}
-
- // 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)
+Bridge::BridgeMasterPort::schedTimingReq(PacketPtr pkt, Tick when)
{
- 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);
+ if (transmitList.empty()) {
+ bridge.schedule(sendEvent, when);
}
- assert(requestQueue.size() != reqQueueLimit);
+ assert(transmitList.size() != reqQueueLimit);
- requestQueue.push_back(DeferredRequest(pkt, readyTime));
+ transmitList.push_back(DeferredPacket(pkt, when));
}
void
-Bridge::BridgeSlavePort::queueForSendTiming(PacketPtr pkt)
+Bridge::BridgeSlavePort::schedTimingResp(PacketPtr pkt, Tick when)
{
- // 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);
+ if (transmitList.empty()) {
+ bridge.schedule(sendEvent, when);
}
- responseQueue.push_back(DeferredResponse(pkt, readyTime));
+
+ transmitList.push_back(DeferredPacket(pkt, when));
}
void
-Bridge::BridgeMasterPort::trySend()
+Bridge::BridgeMasterPort::trySendTiming()
{
- assert(!requestQueue.empty());
+ assert(!transmitList.empty());
- DeferredRequest req = requestQueue.front();
+ DeferredPacket req = transmitList.front();
- assert(req.ready <= curTick());
+ assert(req.tick <= curTick());
PacketPtr pkt = req.pkt;
- DPRINTF(BusBridge, "trySend request: addr 0x%x\n", pkt->getAddr());
+ DPRINTF(Bridge, "trySend request addr 0x%x, queue size %d\n",
+ pkt->getAddr(), transmitList.size());
if (sendTimingReq(pkt)) {
// send successful
- requestQueue.pop_front();
+ transmitList.pop_front();
+ DPRINTF(Bridge, "trySend request successful\n");
// 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));
+ if (!transmitList.empty()) {
+ DeferredPacket next_req = transmitList.front();
+ DPRINTF(Bridge, "Scheduling next send\n");
+ bridge.schedule(sendEvent, std::max(next_req.tick,
+ bridge.clockEdge()));
}
- } else {
- inRetry = true;
+
+ // if we have stalled a request due to a full request queue,
+ // then send a retry at this point, also note that if the
+ // request we stalled was waiting for the response queue
+ // rather than the request queue we might stall it again
+ slavePort.retryStalledReq();
}
- DPRINTF(BusBridge, "trySend: request queue size: %d\n",
- requestQueue.size());
+ // if the send failed, then we try again once we receive a retry,
+ // and therefore there is no need to take any action
}
void
-Bridge::BridgeSlavePort::trySend()
+Bridge::BridgeSlavePort::trySendTiming()
{
- assert(!responseQueue.empty());
+ assert(!transmitList.empty());
- DeferredResponse resp = responseQueue.front();
+ DeferredPacket resp = transmitList.front();
- assert(resp.ready <= curTick());
+ assert(resp.tick <= 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;
+ DPRINTF(Bridge, "trySend response addr 0x%x, outstanding %d\n",
+ pkt->getAddr(), outstandingResponses);
if (sendTimingResp(pkt)) {
- DPRINTF(BusBridge, " successful\n");
// send successful
- responseQueue.pop_front();
+ transmitList.pop_front();
+ DPRINTF(Bridge, "trySend response successful\n");
- if (!was_nacked_here) {
- assert(outstandingResponses != 0);
- --outstandingResponses;
- }
+ 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));
+ if (!transmitList.empty()) {
+ DeferredPacket next_resp = transmitList.front();
+ DPRINTF(Bridge, "Scheduling next send\n");
+ bridge.schedule(sendEvent, std::max(next_resp.tick,
+ bridge.clockEdge()));
+ }
+
+ // if there is space in the request queue and we were stalling
+ // a request, it will definitely be possible to accept it now
+ // since there is guaranteed space in the response queue
+ if (!masterPort.reqQueueFull() && retryReq) {
+ DPRINTF(Bridge, "Request waiting for retry, now retrying\n");
+ retryReq = false;
+ sendRetry();
}
- } else {
- DPRINTF(BusBridge, " unsuccessful\n");
- inRetry = true;
}
- DPRINTF(BusBridge, "trySend: queue size: %d outstanding resp: %d\n",
- responseQueue.size(), outstandingResponses);
+ // if the send failed, then we try again once we receive a retry,
+ // and therefore there is no need to take any action
}
void
Bridge::BridgeMasterPort::recvRetry()
{
- inRetry = false;
- Tick nextReady = requestQueue.front().ready;
- if (nextReady <= curTick())
- trySend();
- else
- bridge->schedule(sendEvent, nextReady);
+ trySendTiming();
}
void
Bridge::BridgeSlavePort::recvRetry()
{
- inRetry = false;
- Tick nextReady = responseQueue.front().ready;
- if (nextReady <= curTick())
- trySend();
- else
- bridge->schedule(sendEvent, nextReady);
+ trySendTiming();
}
Tick
Bridge::BridgeSlavePort::recvAtomic(PacketPtr pkt)
{
- return delay + masterPort.sendAtomic(pkt);
+ return delay * bridge.clockPeriod() + 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) {
+ for (auto i = transmitList.begin(); i != transmitList.end(); ++i) {
if (pkt->checkFunctional((*i).pkt)) {
pkt->makeResponse();
return;
Bridge::BridgeMasterPort::checkFunctional(PacketPtr pkt)
{
bool found = false;
- std::list<DeferredRequest>::iterator i = requestQueue.begin();
+ auto i = transmitList.begin();
- while(i != requestQueue.end() && !found) {
+ while(i != transmitList.end() && !found) {
if (pkt->checkFunctional((*i).pkt)) {
pkt->makeResponse();
found = true;
}
AddrRangeList
-Bridge::BridgeSlavePort::getAddrRanges()
+Bridge::BridgeSlavePort::getAddrRanges() const
{
return ranges;
}
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