2 * Copyright (c) 2006 The Regents of The University of Michigan
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33 * Definition of a bus object.
37 #include "base/misc.hh"
38 #include "base/trace.hh"
40 #include "sim/builder.hh"
43 Bus::getPort(const std::string
&if_name
, int idx
)
45 if (if_name
== "default") {
46 if (defaultPort
== NULL
) {
47 defaultPort
= new BusPort(csprintf("%s-default",name()), this,
51 fatal("Default port already set\n");
54 // if_name ignored? forced to be empty?
55 int id
= interfaces
.size();
56 BusPort
*bp
= new BusPort(csprintf("%s-p%d", name(), id
), this, id
);
57 interfaces
.push_back(bp
);
61 /** Get the ranges of anyone other buses that we are connected to. */
65 std::vector
<BusPort
*>::iterator intIter
;
67 for (intIter
= interfaces
.begin(); intIter
!= interfaces
.end(); intIter
++)
68 (*intIter
)->sendStatusChange(Port::RangeChange
);
71 Bus::BusFreeEvent::BusFreeEvent(Bus
*_bus
) : Event(&mainEventQueue
), bus(_bus
)
74 void Bus::BusFreeEvent::process()
79 const char * Bus::BusFreeEvent::description()
81 return "bus became available";
84 void Bus::occupyBus(PacketPtr pkt
)
86 //Bring tickNextIdle up to the present tick
87 //There is some potential ambiguity where a cycle starts, which might make
88 //a difference when devices are acting right around a cycle boundary. Using
89 //a < allows things which happen exactly on a cycle boundary to take up only
90 //the following cycle. Anthing that happens later will have to "wait" for
91 //the end of that cycle, and then start using the bus after that.
92 while (tickNextIdle
< curTick
)
93 tickNextIdle
+= clock
;
95 // The packet will be sent. Figure out how long it occupies the bus, and
96 // how much of that time is for the first "word", aka bus width.
98 // Requests need one cycle to send an address
101 else if (pkt
->isResponse() || pkt
->hasData()) {
102 // If a packet has data, it needs ceil(size/width) cycles to send it
103 // We're using the "adding instead of dividing" trick again here
104 if (pkt
->hasData()) {
105 int dataSize
= pkt
->getSize();
106 for (int transmitted
= 0; transmitted
< dataSize
;
107 transmitted
+= width
) {
111 // If the packet didn't have data, it must have been a response.
112 // Those use the bus for one cycle to send their data.
117 // The first word will be delivered after the current tick, the delivery
118 // of the address if any, and one bus cycle to deliver the data
121 pkt
->isRequest() ? clock
: 0 +
124 //Advance it numCycles bus cycles.
125 //XXX Should this use the repeated addition trick as well?
126 tickNextIdle
+= (numCycles
* clock
);
127 if (!busIdle
.scheduled()) {
128 busIdle
.schedule(tickNextIdle
);
130 busIdle
.reschedule(tickNextIdle
);
132 DPRINTF(Bus
, "The bus is now occupied from tick %d to %d\n",
133 curTick
, tickNextIdle
);
135 // The bus will become idle once the current packet is delivered.
136 pkt
->finishTime
= tickNextIdle
;
139 /** Function called by the port when the bus is receiving a Timing
142 Bus::recvTiming(PacketPtr pkt
)
145 DPRINTF(Bus
, "recvTiming: packet src %d dest %d addr 0x%x cmd %s\n",
146 pkt
->getSrc(), pkt
->getDest(), pkt
->getAddr(), pkt
->cmdString());
149 if (pkt
->getSrc() == defaultId
)
150 pktPort
= defaultPort
;
151 else pktPort
= interfaces
[pkt
->getSrc()];
153 // If the bus is busy, or other devices are in line ahead of the current
154 // one, put this device on the retry list.
155 if (tickNextIdle
> curTick
||
156 (retryList
.size() && (!inRetry
|| pktPort
!= retryList
.front()))) {
157 addToRetryList(pktPort
);
161 short dest
= pkt
->getDest();
162 if (dest
== Packet::Broadcast
) {
163 if (timingSnoop(pkt
)) {
166 pkt
->flags
|= SNOOP_COMMIT
;
167 success
= timingSnoop(pkt
);
170 if (pkt
->flags
& SATISFIED
) {
171 //Cache-Cache transfer occuring
173 retryList
.front()->onRetryList(false);
174 retryList
.pop_front();
180 port
= findPort(pkt
->getAddr(), pkt
->getSrc());
182 //Snoop didn't succeed
183 DPRINTF(Bus
, "Adding a retry to RETRY list %i\n", pktPort
);
184 addToRetryList(pktPort
);
188 assert(dest
>= 0 && dest
< interfaces
.size());
189 assert(dest
!= pkt
->getSrc()); // catch infinite loops
190 port
= interfaces
[dest
];
195 if (port
->sendTiming(pkt
)) {
196 // Packet was successfully sent. Return true.
197 // Also take care of retries
199 DPRINTF(Bus
, "Remove retry from list %i\n", retryList
.front());
200 retryList
.front()->onRetryList(false);
201 retryList
.pop_front();
207 // Packet not successfully sent. Leave or put it on the retry list.
208 DPRINTF(Bus
, "Adding a retry to RETRY list %i\n", pktPort
);
209 addToRetryList(pktPort
);
214 Bus::recvRetry(int id
)
216 DPRINTF(Bus
, "Received a retry\n");
217 // If there's anything waiting, and the bus isn't busy...
218 if (retryList
.size() && curTick
>= tickNextIdle
) {
219 //retryingPort = retryList.front();
221 DPRINTF(Bus
, "Sending a retry\n");
222 retryList
.front()->sendRetry();
223 // If inRetry is still true, sendTiming wasn't called
226 retryList
.front()->onRetryList(false);
227 retryList
.pop_front();
230 //Bring tickNextIdle up to the present
231 while (tickNextIdle
< curTick
)
232 tickNextIdle
+= clock
;
234 //Burn a cycle for the missed grant.
235 tickNextIdle
+= clock
;
237 if (!busIdle
.scheduled()) {
238 busIdle
.schedule(tickNextIdle
);
240 busIdle
.reschedule(tickNextIdle
);
244 //If we weren't able to drain before, we might be able to now.
245 if (drainEvent
&& retryList
.size() == 0 && curTick
>= tickNextIdle
) {
246 drainEvent
->process();
247 // Clear the drain event once we're done with it.
253 Bus::findPort(Addr addr
, int id
)
255 /* An interval tree would be a better way to do this. --ali. */
261 while (i
< portList
.size() && !found
)
263 if (portList
[i
].range
== addr
) {
264 dest_id
= portList
[i
].portId
;
266 DPRINTF(Bus
, " found addr %#llx on device %d\n", addr
, dest_id
);
271 // Check if this matches the default range
273 for (iter
= defaultRange
.begin(); iter
!= defaultRange
.end(); iter
++) {
275 DPRINTF(Bus
, " found addr %#llx on default\n", addr
);
281 panic("Unable to find destination for addr (user set default "
282 "responder): %#llx", addr
);
284 DPRINTF(Bus
, "Unable to find destination for addr: %#llx, will use "
285 "default port", addr
);
292 // we shouldn't be sending this back to where it came from
293 // only on a functional access and then we should terminate
294 // the cyclical call.
298 return interfaces
[dest_id
];
302 Bus::findSnoopPorts(Addr addr
, int id
)
306 std::vector
<int> ports
;
308 while (i
< portSnoopList
.size())
310 if (portSnoopList
[i
].range
== addr
&& portSnoopList
[i
].portId
!= id
) {
311 //Careful to not overlap ranges
312 //or snoop will be called more than once on the port
313 ports
.push_back(portSnoopList
[i
].portId
);
314 // DPRINTF(Bus, " found snoop addr %#llx on device%d\n", addr,
315 // portSnoopList[i].portId);
323 Bus::atomicSnoop(PacketPtr pkt
)
325 std::vector
<int> ports
= findSnoopPorts(pkt
->getAddr(), pkt
->getSrc());
326 Tick response_time
= 0;
328 while (!ports
.empty())
330 Tick response
= interfaces
[ports
.back()]->sendAtomic(pkt
);
332 assert(!response_time
); //Multiple responders
333 response_time
= response
;
337 return response_time
;
341 Bus::functionalSnoop(PacketPtr pkt
)
343 std::vector
<int> ports
= findSnoopPorts(pkt
->getAddr(), pkt
->getSrc());
345 while (!ports
.empty() && pkt
->result
!= Packet::Success
)
347 interfaces
[ports
.back()]->sendFunctional(pkt
);
353 Bus::timingSnoop(PacketPtr pkt
)
355 std::vector
<int> ports
= findSnoopPorts(pkt
->getAddr(), pkt
->getSrc());
358 while (!ports
.empty() && success
)
360 success
= interfaces
[ports
.back()]->sendTiming(pkt
);
368 /** Function called by the port when the bus is receiving a Atomic
371 Bus::recvAtomic(PacketPtr pkt
)
373 DPRINTF(Bus
, "recvAtomic: packet src %d dest %d addr 0x%x cmd %s\n",
374 pkt
->getSrc(), pkt
->getDest(), pkt
->getAddr(), pkt
->cmdString());
375 assert(pkt
->getDest() == Packet::Broadcast
);
377 // Assume one bus cycle in order to get through. This may have
378 // some clock skew issues yet again...
379 pkt
->finishTime
= curTick
+ clock
;
380 Tick snoopTime
= atomicSnoop(pkt
);
382 return snoopTime
; //Snoop satisfies it
384 return findPort(pkt
->getAddr(), pkt
->getSrc())->sendAtomic(pkt
);
387 /** Function called by the port when the bus is receiving a Functional
390 Bus::recvFunctional(PacketPtr pkt
)
392 DPRINTF(Bus
, "recvFunctional: packet src %d dest %d addr 0x%x cmd %s\n",
393 pkt
->getSrc(), pkt
->getDest(), pkt
->getAddr(), pkt
->cmdString());
394 assert(pkt
->getDest() == Packet::Broadcast
);
395 functionalSnoop(pkt
);
397 // If the snooping found what we were looking for, we're done.
398 if (pkt
->result
!= Packet::Success
) {
399 Port
* port
= findPort(pkt
->getAddr(), pkt
->getSrc());
401 port
->sendFunctional(pkt
);
405 /** Function called by the port when the bus is receiving a status change.*/
407 Bus::recvStatusChange(Port::Status status
, int id
)
409 AddrRangeList ranges
;
410 AddrRangeList snoops
;
414 assert(status
== Port::RangeChange
&&
415 "The other statuses need to be implemented.");
417 DPRINTF(BusAddrRanges
, "received RangeChange from device id %d\n", id
);
419 if (id
== defaultId
) {
420 defaultRange
.clear();
421 // Only try to update these ranges if the user set a default responder.
423 defaultPort
->getPeerAddressRanges(ranges
, snoops
);
424 assert(snoops
.size() == 0);
425 for(iter
= ranges
.begin(); iter
!= ranges
.end(); iter
++) {
426 defaultRange
.push_back(*iter
);
427 DPRINTF(BusAddrRanges
, "Adding range %#llx - %#llx for default range\n",
428 iter
->start
, iter
->end
);
433 assert((id
< interfaces
.size() && id
>= 0) || id
== defaultId
);
434 Port
*port
= interfaces
[id
];
435 std::vector
<DevMap
>::iterator portIter
;
436 std::vector
<DevMap
>::iterator snoopIter
;
438 // Clean out any previously existent ids
439 for (portIter
= portList
.begin(); portIter
!= portList
.end(); ) {
440 if (portIter
->portId
== id
)
441 portIter
= portList
.erase(portIter
);
446 for (snoopIter
= portSnoopList
.begin(); snoopIter
!= portSnoopList
.end(); ) {
447 if (snoopIter
->portId
== id
)
448 snoopIter
= portSnoopList
.erase(snoopIter
);
453 port
->getPeerAddressRanges(ranges
, snoops
);
455 for(iter
= snoops
.begin(); iter
!= snoops
.end(); iter
++) {
460 DPRINTF(BusAddrRanges
, "Adding snoop range %#llx - %#llx for id %d\n",
461 dm
.range
.start
, dm
.range
.end
, id
);
462 portSnoopList
.push_back(dm
);
465 for(iter
= ranges
.begin(); iter
!= ranges
.end(); iter
++) {
470 DPRINTF(BusAddrRanges
, "Adding range %#llx - %#llx for id %d\n",
471 dm
.range
.start
, dm
.range
.end
, id
);
472 portList
.push_back(dm
);
475 DPRINTF(MMU
, "port list has %d entries\n", portList
.size());
477 // tell all our peers that our address range has changed.
478 // Don't tell the device that caused this change, it already knows
479 for (x
= 0; x
< interfaces
.size(); x
++)
481 interfaces
[x
]->sendStatusChange(Port::RangeChange
);
483 if (id
!= defaultId
&& defaultPort
)
484 defaultPort
->sendStatusChange(Port::RangeChange
);
488 Bus::addressRanges(AddrRangeList
&resp
, AddrRangeList
&snoop
, int id
)
490 std::vector
<DevMap
>::iterator portIter
;
491 AddrRangeIter dflt_iter
;
497 DPRINTF(BusAddrRanges
, "received address range request, returning:\n");
499 for (dflt_iter
= defaultRange
.begin(); dflt_iter
!= defaultRange
.end();
501 resp
.push_back(*dflt_iter
);
502 DPRINTF(BusAddrRanges
, " -- Dflt: %#llx : %#llx\n",dflt_iter
->start
,
505 for (portIter
= portList
.begin(); portIter
!= portList
.end(); portIter
++) {
507 for (dflt_iter
= defaultRange
.begin(); dflt_iter
!= defaultRange
.end();
509 if ((portIter
->range
.start
< dflt_iter
->start
&&
510 portIter
->range
.end
>= dflt_iter
->start
) ||
511 (portIter
->range
.start
< dflt_iter
->end
&&
512 portIter
->range
.end
>= dflt_iter
->end
))
513 fatal("Devices can not set ranges that itersect the default set\
514 but are not a subset of the default set.\n");
515 if (portIter
->range
.start
>= dflt_iter
->start
&&
516 portIter
->range
.end
<= dflt_iter
->end
) {
518 DPRINTF(BusAddrRanges
, " -- %#llx : %#llx is a SUBSET\n",
519 portIter
->range
.start
, portIter
->range
.end
);
522 if (portIter
->portId
!= id
&& !subset
) {
523 resp
.push_back(portIter
->range
);
524 DPRINTF(BusAddrRanges
, " -- %#llx : %#llx\n",
525 portIter
->range
.start
, portIter
->range
.end
);
529 for (portIter
= portSnoopList
.begin();
530 portIter
!= portSnoopList
.end(); portIter
++)
532 if (portIter
->portId
!= id
) {
533 snoop
.push_back(portIter
->range
);
534 DPRINTF(BusAddrRanges
, " -- Snoop: %#llx : %#llx\n",
535 portIter
->range
.start
, portIter
->range
.end
);
541 Bus::drain(Event
* de
)
543 //We should check that we're not "doing" anything, and that noone is
544 //waiting. We might be idle but have someone waiting if the device we
545 //contacted for a retry didn't actually retry.
546 if (curTick
>= tickNextIdle
&& retryList
.size() == 0) {
554 BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bus
)
559 Param
<bool> responder_set
;
561 END_DECLARE_SIM_OBJECT_PARAMS(Bus
)
563 BEGIN_INIT_SIM_OBJECT_PARAMS(Bus
)
564 INIT_PARAM(bus_id
, "a globally unique bus id"),
565 INIT_PARAM(clock
, "bus clock speed"),
566 INIT_PARAM(width
, "width of the bus (bits)"),
567 INIT_PARAM(responder_set
, "Is a default responder set by the user")
568 END_INIT_SIM_OBJECT_PARAMS(Bus
)
570 CREATE_SIM_OBJECT(Bus
)
572 return new Bus(getInstanceName(), bus_id
, clock
, width
, responder_set
);
575 REGISTER_SIM_OBJECT("Bus", Bus
)