*/
/**
- * @file Definition of a bus object.
+ * @file
+ * Definition of a bus object.
*/
void
Bus::init()
{
- std::vector<Port*>::iterator intIter;
+ std::vector<BusPort*>::iterator intIter;
for (intIter = interfaces.begin(); intIter != interfaces.end(); intIter++)
(*intIter)->sendStatusChange(Port::RangeChange);
}
+Bus::BusFreeEvent::BusFreeEvent(Bus *_bus) : Event(&mainEventQueue), bus(_bus)
+{}
+
+void Bus::BusFreeEvent::process()
+{
+ bus->recvRetry(-1);
+}
+
+const char * Bus::BusFreeEvent::description()
+{
+ return "bus became available";
+}
+
+void Bus::occupyBus(PacketPtr pkt)
+{
+ //Bring tickNextIdle up to the present tick
+ //There is some potential ambiguity where a cycle starts, which might make
+ //a difference when devices are acting right around a cycle boundary. Using
+ //a < allows things which happen exactly on a cycle boundary to take up only
+ //the following cycle. Anthing that happens later will have to "wait" for
+ //the end of that cycle, and then start using the bus after that.
+ while (tickNextIdle < curTick)
+ tickNextIdle += clock;
+
+ // The packet will be sent. Figure out how long it occupies the bus, and
+ // how much of that time is for the first "word", aka bus width.
+ int numCycles = 0;
+ // Requests need one cycle to send an address
+ if (pkt->isRequest())
+ numCycles++;
+ else if (pkt->isResponse() || pkt->hasData()) {
+ // If a packet has data, it needs ceil(size/width) cycles to send it
+ // We're using the "adding instead of dividing" trick again here
+ if (pkt->hasData()) {
+ int dataSize = pkt->getSize();
+ for (int transmitted = 0; transmitted < dataSize;
+ transmitted += width) {
+ numCycles++;
+ }
+ } else {
+ // If the packet didn't have data, it must have been a response.
+ // Those use the bus for one cycle to send their data.
+ numCycles++;
+ }
+ }
+
+ // The first word will be delivered after the current tick, the delivery
+ // of the address if any, and one bus cycle to deliver the data
+ pkt->firstWordTime =
+ tickNextIdle +
+ pkt->isRequest() ? clock : 0 +
+ clock;
+
+ //Advance it numCycles bus cycles.
+ //XXX Should this use the repeated addition trick as well?
+ tickNextIdle += (numCycles * clock);
+ if (!busIdle.scheduled()) {
+ busIdle.schedule(tickNextIdle);
+ } else {
+ busIdle.reschedule(tickNextIdle);
+ }
+ DPRINTF(Bus, "The bus is now occupied from tick %d to %d\n",
+ curTick, tickNextIdle);
+
+ // The bus will become idle once the current packet is delivered.
+ pkt->finishTime = tickNextIdle;
+}
/** Function called by the port when the bus is receiving a Timing
* transaction.*/
DPRINTF(Bus, "recvTiming: packet src %d dest %d addr 0x%x cmd %s\n",
pkt->getSrc(), pkt->getDest(), pkt->getAddr(), pkt->cmdString());
+ BusPort *pktPort = interfaces[pkt->getSrc()];
+
+ // If the bus is busy, or other devices are in line ahead of the current
+ // one, put this device on the retry list.
+ if (tickNextIdle > curTick ||
+ (retryList.size() && (!inRetry || pktPort != retryList.front()))) {
+ addToRetryList(pktPort);
+ return false;
+ }
+
short dest = pkt->getDest();
if (dest == Packet::Broadcast) {
- port = findPort(pkt->getAddr(), pkt->getSrc());
+ if (timingSnoop(pkt)) {
+ pkt->flags |= SNOOP_COMMIT;
+ bool success = timingSnoop(pkt);
+ assert(success);
+ if (pkt->flags & SATISFIED) {
+ //Cache-Cache transfer occuring
+ if (inRetry) {
+ retryList.front()->onRetryList(false);
+ retryList.pop_front();
+ inRetry = false;
+ }
+ occupyBus(pkt);
+ return true;
+ }
+ port = findPort(pkt->getAddr(), pkt->getSrc());
+ } else {
+ //Snoop didn't succeed
+ addToRetryList(pktPort);
+ return false;
+ }
} else {
assert(dest >= 0 && dest < interfaces.size());
assert(dest != pkt->getSrc()); // catch infinite loops
port = interfaces[dest];
}
+
+ occupyBus(pkt);
+
if (port->sendTiming(pkt)) {
- // packet was successfully sent, just return true.
+ // Packet was successfully sent. Return true.
+ // Also take care of retries
+ if (inRetry) {
+ DPRINTF(Bus, "Remove retry from list %i\n", retryList.front());
+ retryList.front()->onRetryList(false);
+ retryList.pop_front();
+ inRetry = false;
+ }
return true;
}
- // packet not successfully sent
- retryList.push_back(interfaces[pkt->getSrc()]);
+ // Packet not successfully sent. Leave or put it on the retry list.
+ DPRINTF(Bus, "Adding a retry to RETRY list %i\n", pktPort);
+ addToRetryList(pktPort);
return false;
}
void
Bus::recvRetry(int id)
{
- // Go through all the elements on the list calling sendRetry on each
- // This is not very efficient at all but it works. Ultimately we should end
- // up with something that is more intelligent.
- int initialSize = retryList.size();
- int i;
- Port *p;
-
- for (i = 0; i < initialSize; i++) {
- assert(retryList.size() > 0);
- p = retryList.front();
- retryList.pop_front();
- p->sendRetry();
+ DPRINTF(Bus, "Received a retry\n");
+ // If there's anything waiting...
+ if (retryList.size()) {
+ //retryingPort = retryList.front();
+ inRetry = true;
+ DPRINTF(Bus, "Sending a retry\n");
+ retryList.front()->sendRetry();
+ // If inRetry is still true, sendTiming wasn't called
+ if (inRetry)
+ panic("Port %s didn't call sendTiming in it's recvRetry\n",\
+ retryList.front()->getPeer()->name());
+ //assert(!inRetry);
}
}
-
Port *
Bus::findPort(Addr addr, int id)
{
if (portList[i].range == addr) {
dest_id = portList[i].portId;
found = true;
- DPRINTF(Bus, " found addr 0x%llx on device %d\n", addr, dest_id);
+ DPRINTF(Bus, " found addr %#llx on device %d\n", addr, dest_id);
}
i++;
}
if (dest_id == -1) {
for (iter = defaultRange.begin(); iter != defaultRange.end(); iter++) {
if (*iter == addr) {
- DPRINTF(Bus, " found addr 0x%llx on default\n", addr);
+ DPRINTF(Bus, " found addr %#llx on default\n", addr);
return defaultPort;
}
}
- panic("Unable to find destination for addr: %llx", addr);
+ panic("Unable to find destination for addr: %#llx", addr);
}
return interfaces[dest_id];
}
+std::vector<int>
+Bus::findSnoopPorts(Addr addr, int id)
+{
+ int i = 0;
+ AddrRangeIter iter;
+ std::vector<int> ports;
+
+ while (i < portSnoopList.size())
+ {
+ if (portSnoopList[i].range == addr && portSnoopList[i].portId != id) {
+ //Careful to not overlap ranges
+ //or snoop will be called more than once on the port
+ ports.push_back(portSnoopList[i].portId);
+// DPRINTF(Bus, " found snoop addr %#llx on device%d\n", addr,
+// portSnoopList[i].portId);
+ }
+ i++;
+ }
+ return ports;
+}
+
+void
+Bus::atomicSnoop(Packet *pkt)
+{
+ std::vector<int> ports = findSnoopPorts(pkt->getAddr(), pkt->getSrc());
+
+ while (!ports.empty())
+ {
+ interfaces[ports.back()]->sendAtomic(pkt);
+ ports.pop_back();
+ }
+}
+
+void
+Bus::functionalSnoop(Packet *pkt)
+{
+ std::vector<int> ports = findSnoopPorts(pkt->getAddr(), pkt->getSrc());
+
+ while (!ports.empty())
+ {
+ interfaces[ports.back()]->sendFunctional(pkt);
+ ports.pop_back();
+ }
+}
+
+bool
+Bus::timingSnoop(Packet *pkt)
+{
+ std::vector<int> ports = findSnoopPorts(pkt->getAddr(), pkt->getSrc());
+ bool success = true;
+
+ while (!ports.empty() && success)
+ {
+ success = interfaces[ports.back()]->sendTiming(pkt);
+ ports.pop_back();
+ }
+
+ return success;
+}
+
+
/** Function called by the port when the bus is receiving a Atomic
* transaction.*/
Tick
DPRINTF(Bus, "recvAtomic: packet src %d dest %d addr 0x%x cmd %s\n",
pkt->getSrc(), pkt->getDest(), pkt->getAddr(), pkt->cmdString());
assert(pkt->getDest() == Packet::Broadcast);
+ atomicSnoop(pkt);
return findPort(pkt->getAddr(), pkt->getSrc())->sendAtomic(pkt);
}
DPRINTF(Bus, "recvFunctional: packet src %d dest %d addr 0x%x cmd %s\n",
pkt->getSrc(), pkt->getDest(), pkt->getAddr(), pkt->cmdString());
assert(pkt->getDest() == Packet::Broadcast);
+ functionalSnoop(pkt);
findPort(pkt->getAddr(), pkt->getSrc())->sendFunctional(pkt);
}
assert(snoops.size() == 0);
for(iter = ranges.begin(); iter != ranges.end(); iter++) {
defaultRange.push_back(*iter);
- DPRINTF(BusAddrRanges, "Adding range %llx - %llx for default\n",
+ DPRINTF(BusAddrRanges, "Adding range %#llx - %#llx for default range\n",
iter->start, iter->end);
}
} else {
assert((id < interfaces.size() && id >= 0) || id == -1);
Port *port = interfaces[id];
std::vector<DevMap>::iterator portIter;
+ std::vector<DevMap>::iterator snoopIter;
// Clean out any previously existent ids
for (portIter = portList.begin(); portIter != portList.end(); ) {
portIter++;
}
+ for (snoopIter = portSnoopList.begin(); snoopIter != portSnoopList.end(); ) {
+ if (snoopIter->portId == id)
+ snoopIter = portSnoopList.erase(snoopIter);
+ else
+ snoopIter++;
+ }
+
port->getPeerAddressRanges(ranges, snoops);
- // not dealing with snooping yet either
- assert(snoops.size() == 0);
+ for(iter = snoops.begin(); iter != snoops.end(); iter++) {
+ DevMap dm;
+ dm.portId = id;
+ dm.range = *iter;
+
+ DPRINTF(BusAddrRanges, "Adding snoop range %#llx - %#llx for id %d\n",
+ dm.range.start, dm.range.end, id);
+ portSnoopList.push_back(dm);
+ }
+
for(iter = ranges.begin(); iter != ranges.end(); iter++) {
DevMap dm;
dm.portId = id;
dm.range = *iter;
- DPRINTF(BusAddrRanges, "Adding range %llx - %llx for id %d\n",
+ DPRINTF(BusAddrRanges, "Adding range %#llx - %#llx for id %d\n",
dm.range.start, dm.range.end, id);
portList.push_back(dm);
}
for (dflt_iter = defaultRange.begin(); dflt_iter != defaultRange.end();
dflt_iter++) {
resp.push_back(*dflt_iter);
- DPRINTF(BusAddrRanges, " -- %#llX : %#llX\n",dflt_iter->start,
+ DPRINTF(BusAddrRanges, " -- %#llx : %#llx\n",dflt_iter->start,
dflt_iter->end);
}
for (portIter = portList.begin(); portIter != portList.end(); portIter++) {
if (portIter->range.start >= dflt_iter->start &&
portIter->range.end <= dflt_iter->end) {
subset = true;
- DPRINTF(BusAddrRanges, " -- %#llX : %#llX is a SUBSET\n",
+ DPRINTF(BusAddrRanges, " -- %#llx : %#llx is a SUBSET\n",
portIter->range.start, portIter->range.end);
}
}
if (portIter->portId != id && !subset) {
resp.push_back(portIter->range);
- DPRINTF(BusAddrRanges, " -- %#llX : %#llX\n",
+ DPRINTF(BusAddrRanges, " -- %#llx : %#llx\n",
portIter->range.start, portIter->range.end);
}
}
BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bus)
Param<int> bus_id;
+ Param<int> clock;
+ Param<int> width;
END_DECLARE_SIM_OBJECT_PARAMS(Bus)
BEGIN_INIT_SIM_OBJECT_PARAMS(Bus)
- INIT_PARAM(bus_id, "a globally unique bus id")
+ INIT_PARAM(bus_id, "a globally unique bus id"),
+ INIT_PARAM(clock, "bus clock speed"),
+ INIT_PARAM(width, "width of the bus (bits)")
END_INIT_SIM_OBJECT_PARAMS(Bus)
CREATE_SIM_OBJECT(Bus)
{
- return new Bus(getInstanceName(), bus_id);
+ return new Bus(getInstanceName(), bus_id, clock, width);
}
REGISTER_SIM_OBJECT("Bus", Bus)
projects / gem5.git / blobdiff