/*
- * Copyright (c) 2011-2012 ARM Limited
+ * Copyright (c) 2011-2013, 2015 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.
*/
{
// 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 transmitList.size() == reqQueueLimit;
}
DPRINTF(Bridge, "Request queue size: %d\n", transmitList.size());
- slavePort.schedTimingResp(pkt, bridge.clockEdge(delay));
+ // technically the packet only reaches us after the header delay,
+ // and typically we also need to deserialise any payload (unless
+ // the two sides of the bridge are synchronous)
+ Tick receive_delay = pkt->headerDelay + pkt->payloadDelay;
+ pkt->headerDelay = pkt->payloadDelay = 0;
+
+ slavePort.schedTimingResp(pkt, bridge.clockEdge(delay) +
+ receive_delay);
return true;
}
DPRINTF(Bridge, "recvTimingReq: %s addr 0x%x\n",
pkt->cmdString(), pkt->getAddr());
- // ensure we do not have something waiting to retry
- if(retryReq)
+ // if a cache is responding, sink the packet without further
+ // action, also discard any packet that is not a read or a write
+ if (pkt->cacheResponding() ||
+ !(pkt->isWrite() || pkt->isRead())) {
+ assert(!pkt->needsResponse());
+ pendingDelete.reset(pkt);
+ return true;
+ }
+
+ // we should not get a new request after committing to retry the
+ // current one, but unfortunately the CPU violates this rule, so
+ // simply ignore it for now
+ if (retryReq)
return false;
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(Bridge, "Request queue full\n");
retryReq = true;
- } else if (pkt->needsResponse()) {
- if (respQueueFull()) {
- DPRINTF(Bridge, "Response queue full\n");
- retryReq = true;
- } else {
- DPRINTF(Bridge, "Reserving space for response\n");
- assert(outstandingResponses != respQueueLimit);
- ++outstandingResponses;
- retryReq = false;
- masterPort.schedTimingReq(pkt, bridge.clockEdge(delay));
+ } else {
+ // look at the response queue if we expect to see a response
+ bool expects_response = pkt->needsResponse();
+ 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 (!retryReq) {
+ // technically the packet only reaches us after the header
+ // delay, and typically we also need to deserialise any
+ // payload (unless the two sides of the bridge are
+ // synchronous)
+ Tick receive_delay = pkt->headerDelay + pkt->payloadDelay;
+ pkt->headerDelay = pkt->payloadDelay = 0;
+
+ masterPort.schedTimingReq(pkt, bridge.clockEdge(delay) +
+ receive_delay);
}
}
if (retryReq) {
DPRINTF(Bridge, "Request waiting for retry, now retrying\n");
retryReq = false;
- sendRetry();
+ sendRetryReq();
}
}
void
Bridge::BridgeMasterPort::schedTimingReq(PacketPtr pkt, Tick when)
{
- // 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
- pkt->pushSenderState(new RequestState(pkt->getSrc()));
- }
-
// 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
assert(transmitList.size() != reqQueueLimit);
- transmitList.push_back(DeferredPacket(pkt, when));
+ transmitList.emplace_back(pkt, when);
}
void
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->popSenderState());
- assert(req_state != NULL);
- pkt->setDest(req_state->origSrc);
- delete req_state;
-
- // the bridge assumes that at least one bus has set the
- // destination field of the packet
- assert(pkt->isDestValid());
- DPRINTF(Bridge, "response, new dest %d\n", pkt->getDest());
-
// 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
bridge.schedule(sendEvent, when);
}
- transmitList.push_back(DeferredPacket(pkt, when));
+ transmitList.emplace_back(pkt, when);
}
void
// If there are more packets to send, schedule event to try again.
if (!transmitList.empty()) {
- req = transmitList.front();
+ DeferredPacket next_req = transmitList.front();
DPRINTF(Bridge, "Scheduling next send\n");
- bridge.schedule(sendEvent, std::max(req.tick,
- bridge.nextCycle()));
+ bridge.schedule(sendEvent, std::max(next_req.tick,
+ bridge.clockEdge()));
}
// if we have stalled a request due to a full request queue,
// If there are more packets to send, schedule event to try again.
if (!transmitList.empty()) {
- resp = transmitList.front();
+ DeferredPacket next_resp = transmitList.front();
DPRINTF(Bridge, "Scheduling next send\n");
- bridge.schedule(sendEvent, std::max(resp.tick,
- bridge.nextCycle()));
+ bridge.schedule(sendEvent, std::max(next_resp.tick,
+ bridge.clockEdge()));
}
// if there is space in the request queue and we were stalling
if (!masterPort.reqQueueFull() && retryReq) {
DPRINTF(Bridge, "Request waiting for retry, now retrying\n");
retryReq = false;
- sendRetry();
+ sendRetryReq();
}
}
}
void
-Bridge::BridgeMasterPort::recvRetry()
+Bridge::BridgeMasterPort::recvReqRetry()
{
- Tick nextReady = transmitList.front().tick;
- if (nextReady <= curTick())
- trySendTiming();
- else
- bridge.schedule(sendEvent, nextReady);
+ trySendTiming();
}
void
-Bridge::BridgeSlavePort::recvRetry()
+Bridge::BridgeSlavePort::recvRespRetry()
{
- Tick nextReady = transmitList.front().tick;
- if (nextReady <= curTick())
- trySendTiming();
- else
- bridge.schedule(sendEvent, nextReady);
+ trySendTiming();
}
Tick
void
Bridge::BridgeSlavePort::recvFunctional(PacketPtr pkt)
{
- std::list<DeferredPacket>::iterator i;
-
pkt->pushLabel(name());
// check the response queue
- for (i = transmitList.begin(); i != transmitList.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<DeferredPacket>::iterator i = transmitList.begin();
+ auto i = transmitList.begin();
- while(i != transmitList.end() && !found) {
+ while (i != transmitList.end() && !found) {
if (pkt->checkFunctional((*i).pkt)) {
pkt->makeResponse();
found = true;
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