* 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
*/
/**
- * @file Definition of a simple bus bridge without buffering.
+ * @file
+ * Definition of a simple bus bridge without buffering.
*/
+#include <algorithm>
#include "base/trace.hh"
#include "mem/bridge.hh"
#include "sim/builder.hh"
+Bridge::BridgePort::BridgePort(const std::string &_name,
+ Bridge *_bridge, BridgePort *_otherPort,
+ int _delay, int _nack_delay, int _req_limit,
+ int _resp_limit, bool fix_partial_write)
+ : Port(_name), bridge(_bridge), otherPort(_otherPort),
+ delay(_delay), nackDelay(_nack_delay), fixPartialWrite(fix_partial_write),
+ outstandingResponses(0), queuedRequests(0), inRetry(false),
+ reqQueueLimit(_req_limit), respQueueLimit(_resp_limit), sendEvent(this)
+{
+}
+
+Bridge::Bridge(Params *p)
+ : MemObject(p->name),
+ portA(p->name + "-portA", this, &portB, p->delay, p->nack_delay,
+ p->req_size_a, p->resp_size_a, p->fix_partial_write_a),
+ portB(p->name + "-portB", this, &portA, p->delay, p->nack_delay,
+ p->req_size_b, p->resp_size_b, p->fix_partial_write_b),
+ ackWrites(p->write_ack), _params(p)
+{
+ if (ackWrites)
+ panic("No support for acknowledging writes\n");
+}
+
+Port *
+Bridge::getPort(const std::string &if_name, int idx)
+{
+ BridgePort *port;
+
+ if (if_name == "side_a")
+ port = &portA;
+ else if (if_name == "side_b")
+ port = &portB;
+ else
+ return NULL;
+
+ if (port->getPeer() != NULL)
+ panic("bridge side %s already connected to.", if_name);
+ return port;
+}
+
+
void
Bridge::init()
{
// Make sure that both sides are connected to.
- if (sideA == NULL || sideB == NULL)
- panic("Both ports of bus bridge are not connected to a bus.\n");
+ if (portA.getPeer() == NULL || portB.getPeer() == NULL)
+ fatal("Both ports of bus bridge are not connected to a bus.\n");
+
+ if (portA.peerBlockSize() != portB.peerBlockSize())
+ fatal("Busses don't have the same block size... Not supported.\n");
}
+bool
+Bridge::BridgePort::respQueueFull()
+{
+ assert(outstandingResponses >= 0 && outstandingResponses <= respQueueLimit);
+ return outstandingResponses >= respQueueLimit;
+}
-/** Function called by the port when the bus is recieving a Timing
+bool
+Bridge::BridgePort::reqQueueFull()
+{
+ assert(queuedRequests >= 0 && queuedRequests <= reqQueueLimit);
+ return queuedRequests >= reqQueueLimit;
+}
+
+/** Function called by the port when the bus is receiving a Timing
* transaction.*/
bool
-Bridge::recvTiming(Packet *pkt, Side id)
+Bridge::BridgePort::recvTiming(PacketPtr pkt)
{
- if (blockedA && id == SideA)
- return false;
- if (blockedB && id == SideB)
- return false;
-
- if (delay) {
- if (!sendEvent.scheduled())
- sendEvent.schedule(curTick + delay);
- if (id == SideA) {
- inboundA.push_back(std::make_pair<Packet*, Tick>(pkt, curTick));
- blockCheck(SideA);
- } else {
- inboundB.push_back(std::make_pair<Packet*, Tick>(pkt, curTick));
- blockCheck(SideB);
- }
- } else {
- if (id == SideB) {
- sideA->sendPkt(pkt);
- blockCheck(SideB);
+ DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n",
+ pkt->getSrc(), pkt->getDest(), pkt->getAddr());
+
+ DPRINTF(BusBridge, "Local queue size: %d outreq: %d outresp: %d\n",
+ sendQueue.size(), queuedRequests, outstandingResponses);
+ DPRINTF(BusBridge, "Remove queue size: %d outreq: %d outresp: %d\n",
+ otherPort->sendQueue.size(), otherPort->queuedRequests,
+ otherPort->outstandingResponses);
+
+ if (pkt->isRequest() && otherPort->reqQueueFull() && !pkt->wasNacked()) {
+ DPRINTF(BusBridge, "Remote queue full, nacking\n");
+ nackRequest(pkt);
+ return true;
+ }
+
+ if (pkt->needsResponse() && !pkt->wasNacked())
+ if (respQueueFull()) {
+ DPRINTF(BusBridge, "Local queue full, no space for response, nacking\n");
+ DPRINTF(BusBridge, "queue size: %d outreq: %d outstanding resp: %d\n",
+ sendQueue.size(), queuedRequests, outstandingResponses);
+ nackRequest(pkt);
+ return true;
} else {
- sideB->sendPkt(pkt);
- blockCheck(SideA);
+ DPRINTF(BusBridge, "Request Needs response, reserving space\n");
+ ++outstandingResponses;
}
- }
- return true;
+ otherPort->queueForSendTiming(pkt);
+
+ return true;
}
void
-Bridge::blockCheck(Side id)
+Bridge::BridgePort::nackRequest(PacketPtr pkt)
{
- /* Check that we still have buffer space available. */
- if (id == SideB) {
- if (sideA->numQueued() + inboundB.size() >= queueSizeA && !blockedB) {
- sideB->sendStatusChange(Port::Blocked);
- blockedB = true;
- } else if (sideA->numQueued() + inboundB.size() < queueSizeA && blockedB) {
- sideB->sendStatusChange(Port::Unblocked);
- blockedB = false;
- }
- } else {
- if (sideB->numQueued() + inboundA.size() >= queueSizeB && !blockedA) {
- sideA->sendStatusChange(Port::Blocked);
- blockedA = true;
- } else if (sideB->numQueued() + inboundA.size() < queueSizeB && blockedA) {
- sideA->sendStatusChange(Port::Unblocked);
- blockedA = false;
- }
+ // Nack the packet
+ pkt->setNacked();
+ pkt->setDest(pkt->getSrc());
+
+ //put it on the list to send
+ Tick readyTime = curTick + nackDelay;
+ PacketBuffer *buf = new PacketBuffer(pkt, readyTime, true);
+
+ // nothing on the list, add it and we're done
+ if (sendQueue.empty()) {
+ assert(!sendEvent.scheduled());
+ sendEvent.schedule(readyTime);
+ sendQueue.push_back(buf);
+ return;
}
-}
-void Bridge::timerEvent()
-{
- Tick t = 0;
+ assert(sendEvent.scheduled() || inRetry);
- assert(inboundA.size() || inboundB.size());
- if (inboundA.size()) {
- while (inboundA.front().second <= curTick + delay){
- sideB->sendPkt(inboundA.front());
- inboundA.pop_front();
- }
- if (inboundA.size())
- t = inboundA.front().second + delay;
+ // does it go at the end?
+ if (readyTime >= sendQueue.back()->ready) {
+ sendQueue.push_back(buf);
+ return;
}
- if (inboundB.size()) {
- while (inboundB.front().second <= curTick + delay){
- sideB->sendPkt(inboundA.front());
- inboundB.pop_front();
+
+ // ok, somewhere in the middle, fun
+ std::list<PacketBuffer*>::iterator i = sendQueue.begin();
+ std::list<PacketBuffer*>::iterator end = sendQueue.end();
+ std::list<PacketBuffer*>::iterator begin = sendQueue.begin();
+ bool done = false;
+
+ while (i != end && !done) {
+ if (readyTime < (*i)->ready) {
+ if (i == begin)
+ sendEvent.reschedule(readyTime);
+ sendQueue.insert(i,buf);
+ done = true;
}
- if (inboundB.size())
- if (t == 0)
- t = inboundB.front().second + delay;
- else
- t = std::min(t,inboundB.front().second + delay);
- } else {
- panic("timerEvent() called but nothing to do?");
+ i++;
}
-
- if (t != 0)
- sendEvent.schedule(t);
+ assert(done);
}
void
-Bridge::BridgePort::sendPkt(Packet *pkt)
+Bridge::BridgePort::queueForSendTiming(PacketPtr pkt)
{
- if (!sendTiming(pkt))
- outbound.push_back(std::make_pair<Packet*,Tick>(pkt, curTick));
+ if (pkt->isResponse() || pkt->wasNacked()) {
+ // This is a response for a request we forwarded earlier. The
+ // corresponding PacketBuffer should be stored in the packet's
+ // senderState field.
+ PacketBuffer *buf = dynamic_cast<PacketBuffer*>(pkt->senderState);
+ assert(buf != NULL);
+ // set up new packet dest & senderState based on values saved
+ // from original request
+ buf->fixResponse(pkt);
+
+ // Check if this packet was expecting a response and it's a nacked
+ // packet, in which case we will never being seeing it
+ if (buf->expectResponse && pkt->wasNacked())
+ --outstandingResponses;
+
+ DPRINTF(BusBridge, "response, new dest %d\n", pkt->getDest());
+ delete buf;
+ }
+
+
+ if (pkt->isRequest() && !pkt->wasNacked()) {
+ ++queuedRequests;
+ }
+
+
+
+ Tick readyTime = curTick + delay;
+ PacketBuffer *buf = new PacketBuffer(pkt, readyTime);
+
+ // 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 (sendQueue.empty()) {
+ sendEvent.schedule(readyTime);
+ }
+ sendQueue.push_back(buf);
}
void
-Bridge::BridgePort::sendPkt(std::pair<Packet*, Tick> p)
+Bridge::BridgePort::trySend()
{
- if (!sendTiming(p.first))
- outbound.push_back(p);
+ assert(!sendQueue.empty());
+
+ PacketBuffer *buf = sendQueue.front();
+
+ assert(buf->ready <= curTick);
+
+ PacketPtr pkt = buf->pkt;
+
+ // Ugly! @todo When multilevel coherence works this will be removed
+ if (pkt->cmd == MemCmd::WriteInvalidateReq && fixPartialWrite &&
+ !pkt->wasNacked()) {
+ PacketPtr funcPkt = new Packet(pkt->req, MemCmd::WriteReq,
+ Packet::Broadcast);
+ funcPkt->dataStatic(pkt->getPtr<uint8_t>());
+ sendFunctional(funcPkt);
+ pkt->cmd = MemCmd::WriteReq;
+ delete funcPkt;
+ }
+
+ DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n",
+ buf->origSrc, pkt->getDest(), pkt->getAddr());
+
+ bool wasReq = pkt->isRequest();
+ bool wasNacked = pkt->wasNacked();
+
+ if (sendTiming(pkt)) {
+ // send successful
+ sendQueue.pop_front();
+ buf->pkt = NULL; // we no longer own packet, so it's not safe to look at it
+
+ if (buf->expectResponse) {
+ // Must wait for response
+ DPRINTF(BusBridge, " successful: awaiting response (%d)\n",
+ outstandingResponses);
+ } else {
+ // no response expected... deallocate packet buffer now.
+ DPRINTF(BusBridge, " successful: no response expected\n");
+ delete buf;
+ }
+
+ if (!wasNacked) {
+ if (wasReq)
+ --queuedRequests;
+ else
+ --outstandingResponses;
+ }
+
+ // If there are more packets to send, schedule event to try again.
+ if (!sendQueue.empty()) {
+ buf = sendQueue.front();
+ DPRINTF(BusBridge, "Scheduling next send\n");
+ sendEvent.schedule(std::max(buf->ready, curTick + 1));
+ }
+ } else {
+ DPRINTF(BusBridge, " unsuccessful\n");
+ inRetry = true;
+ }
+ DPRINTF(BusBridge, "trySend: queue size: %d outreq: %d outstanding resp: %d\n",
+ sendQueue.size(), queuedRequests, outstandingResponses);
}
-Packet *
+void
Bridge::BridgePort::recvRetry()
{
- Packet *pkt;
- assert(outbound.size() > 0);
- assert(outbound.front().second >= curTick + bridge->delay);
- pkt = outbound.front().first;
- outbound.pop_front();
- bridge->blockCheck(side);
- return pkt;
+ inRetry = false;
+ Tick nextReady = sendQueue.front()->ready;
+ if (nextReady <= curTick)
+ trySend();
+ else
+ sendEvent.schedule(nextReady);
}
-/** Function called by the port when the bus is recieving a Atomic
+/** Function called by the port when the bus is receiving a Atomic
* transaction.*/
Tick
-Bridge::recvAtomic(Packet *pkt, Side id)
+Bridge::BridgePort::recvAtomic(PacketPtr pkt)
{
- pkt->time += delay;
-
- if (id == SideA)
- return sideB->sendAtomic(pkt);
- else
- return sideA->sendAtomic(pkt);
+ // fix partial atomic writes... similar to the timing code that does the
+ // same... will be removed once our code gets this right
+ if (pkt->cmd == MemCmd::WriteInvalidateReq && fixPartialWrite) {
+
+ PacketPtr funcPkt = new Packet(pkt->req, MemCmd::WriteReq,
+ Packet::Broadcast);
+ funcPkt->dataStatic(pkt->getPtr<uint8_t>());
+ otherPort->sendFunctional(funcPkt);
+ delete funcPkt;
+ pkt->cmd = MemCmd::WriteReq;
+ }
+ return delay + otherPort->sendAtomic(pkt);
}
-/** Function called by the port when the bus is recieving a Functional
+/** Function called by the port when the bus is receiving a Functional
* transaction.*/
void
-Bridge::recvFunctional(Packet *pkt, Side id)
+Bridge::BridgePort::recvFunctional(PacketPtr pkt)
{
- pkt->time += delay;
- std::list<std::pair<Packet*, Tick> >::iterator i;
- bool pktContinue = true;
-
- for(i = inboundA.begin(); i != inboundA.end(); ++i) {
- if (pkt->intersect(i->first)) {
- pktContinue &= fixPacket(pkt, i->first);
- }
- }
-
- for(i = inboundB.begin(); i != inboundB.end(); ++i) {
- if (pkt->intersect(i->first)) {
- pktContinue &= fixPacket(pkt, i->first);
- }
- }
-
- for(i = sideA->outbound.begin(); i != sideA->outbound.end(); ++i) {
- if (pkt->intersect(i->first)) {
- pktContinue &= fixPacket(pkt, i->first);
- }
- }
+ std::list<PacketBuffer*>::iterator i;
- for(i = sideB->outbound.begin(); i != sideB->outbound.end(); ++i) {
- if (pkt->intersect(i->first)) {
- pktContinue &= fixPacket(pkt, i->first);
- }
+ for (i = sendQueue.begin(); i != sendQueue.end(); ++i) {
+ if (pkt->checkFunctional((*i)->pkt))
+ return;
}
- if (pktContinue) {
- if (id == SideA)
- sideB->sendFunctional(pkt);
- else
- sideA->sendFunctional(pkt);
- }
+ // fall through if pkt still not satisfied
+ otherPort->sendFunctional(pkt);
}
-/** Function called by the port when the bus is recieving a status change.*/
+/** Function called by the port when the bus is receiving a status change.*/
void
-Bridge::recvStatusChange(Port::Status status, Side id)
+Bridge::BridgePort::recvStatusChange(Port::Status status)
{
- if (status == Port::Blocked || status == Port::Unblocked)
- return ;
-
- if (id == SideA)
- sideB->sendStatusChange(status);
- else
- sideA->sendStatusChange(status);
+ otherPort->sendStatusChange(status);
}
void
-Bridge::addressRanges(AddrRangeList &resp, AddrRangeList &snoop, Side id)
+Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList &resp,
+ bool &snoop)
{
- if (id == SideA)
- sideB->getPeerAddressRanges(resp, snoop);
- else
- sideA->getPeerAddressRanges(resp, snoop);
+ otherPort->getPeerAddressRanges(resp, snoop);
+ // we don't allow snooping across bridges
+ snoop = false;
}
BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bridge)
- Param<int> queue_size_a;
- Param<int> queue_size_b;
+ Param<int> req_size_a;
+ Param<int> req_size_b;
+ Param<int> resp_size_a;
+ Param<int> resp_size_b;
Param<Tick> delay;
+ Param<Tick> nack_delay;
Param<bool> write_ack;
+ Param<bool> fix_partial_write_a;
+ Param<bool> fix_partial_write_b;
END_DECLARE_SIM_OBJECT_PARAMS(Bridge)
BEGIN_INIT_SIM_OBJECT_PARAMS(Bridge)
- INIT_PARAM(queue_size_a, "The size of the queue for data coming into side a"),
- INIT_PARAM(queue_size_b, "The size of the queue for data coming into side b"),
+ INIT_PARAM(req_size_a, "The size of the queue for requests coming into side a"),
+ INIT_PARAM(req_size_b, "The size of the queue for requests coming into side b"),
+ INIT_PARAM(resp_size_a, "The size of the queue for responses coming into side a"),
+ INIT_PARAM(resp_size_b, "The size of the queue for responses coming into side b"),
INIT_PARAM(delay, "The miminum delay to cross this bridge"),
- INIT_PARAM(write_ack, "Acknowledge any writes that are received.")
+ INIT_PARAM(nack_delay, "The minimum delay to nack a packet"),
+ INIT_PARAM(write_ack, "Acknowledge any writes that are received."),
+ INIT_PARAM(fix_partial_write_a, "Fixup any partial block writes that are received"),
+ INIT_PARAM(fix_partial_write_b, "Fixup any partial block writes that are received")
END_INIT_SIM_OBJECT_PARAMS(Bridge)
CREATE_SIM_OBJECT(Bridge)
{
- return new Bridge(getInstanceName(), queue_size_a, queue_size_b, delay,
- write_ack);
+ Bridge::Params *p = new Bridge::Params;
+ p->name = getInstanceName();
+ p->req_size_a = req_size_a;
+ p->req_size_b = req_size_b;
+ p->resp_size_a = resp_size_a;
+ p->resp_size_b = resp_size_b;
+ p->delay = delay;
+ p->nack_delay = nack_delay;
+ p->write_ack = write_ack;
+ p->fix_partial_write_a = fix_partial_write_a;
+ p->fix_partial_write_b = fix_partial_write_b;
+ return new Bridge(p);
}
REGISTER_SIM_OBJECT("Bridge", Bridge)
+
+
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