2 * Copyright (c) 2006 The Regents of The University of Michigan
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33 * Definition of a bus object.
39 #include "base/misc.hh"
40 #include "base/trace.hh"
42 #include "sim/builder.hh"
45 Bus::getPort(const std::string
&if_name
, int idx
)
47 if (if_name
== "default") {
48 if (defaultPort
== NULL
) {
49 defaultPort
= new BusPort(csprintf("%s-default",name()), this,
51 cachedBlockSizeValid
= false;
54 fatal("Default port already set\n");
57 if (if_name
== "functional") {
60 funcPort
= new BusPort(csprintf("%s-p%d-func", name(), id
), this, id
);
62 interfaces
[id
] = funcPort
;
67 // if_name ignored? forced to be empty?
69 assert(maxId
< std::numeric_limits
<typeof(maxId
)>::max());
70 BusPort
*bp
= new BusPort(csprintf("%s-p%d", name(), id
), this, id
);
72 cachedBlockSizeValid
= false;
77 Bus::deletePortRefs(Port
*p
)
80 BusPort
*bp
= dynamic_cast<BusPort
*>(p
);
82 panic("Couldn't convert Port* to BusPort*\n");
83 // If this is our one functional port
86 interfaces
.erase(bp
->getId());
90 /** Get the ranges of anyone other buses that we are connected to. */
94 m5::hash_map
<short,BusPort
*>::iterator intIter
;
96 for (intIter
= interfaces
.begin(); intIter
!= interfaces
.end(); intIter
++)
97 intIter
->second
->sendStatusChange(Port::RangeChange
);
100 Bus::BusFreeEvent::BusFreeEvent(Bus
*_bus
) : Event(&mainEventQueue
), bus(_bus
)
103 void Bus::BusFreeEvent::process()
108 const char * Bus::BusFreeEvent::description()
110 return "bus became available";
113 void Bus::occupyBus(PacketPtr pkt
)
115 //Bring tickNextIdle up to the present tick
116 //There is some potential ambiguity where a cycle starts, which might make
117 //a difference when devices are acting right around a cycle boundary. Using
118 //a < allows things which happen exactly on a cycle boundary to take up
119 //only the following cycle. Anything that happens later will have to "wait"
120 //for the end of that cycle, and then start using the bus after that.
121 if (tickNextIdle
< curTick
) {
122 tickNextIdle
= curTick
;
123 if (tickNextIdle
% clock
!= 0)
124 tickNextIdle
= curTick
- (curTick
% clock
) + clock
;
127 // The packet will be sent. Figure out how long it occupies the bus, and
128 // how much of that time is for the first "word", aka bus width.
130 // Requests need one cycle to send an address
131 if (pkt
->isRequest())
133 else if (pkt
->isResponse() || pkt
->hasData()) {
134 // If a packet has data, it needs ceil(size/width) cycles to send it
135 // We're using the "adding instead of dividing" trick again here
136 if (pkt
->hasData()) {
137 int dataSize
= pkt
->getSize();
138 numCycles
+= dataSize
/width
;
139 if (dataSize
% width
)
142 // If the packet didn't have data, it must have been a response.
143 // Those use the bus for one cycle to send their data.
148 // The first word will be delivered after the current tick, the delivery
149 // of the address if any, and one bus cycle to deliver the data
152 pkt
->isRequest() ? clock
: 0 +
155 //Advance it numCycles bus cycles.
156 //XXX Should this use the repeated addition trick as well?
157 tickNextIdle
+= (numCycles
* clock
);
158 if (!busIdle
.scheduled()) {
159 busIdle
.schedule(tickNextIdle
);
161 busIdle
.reschedule(tickNextIdle
);
163 DPRINTF(Bus
, "The bus is now occupied from tick %d to %d\n",
164 curTick
, tickNextIdle
);
166 // The bus will become idle once the current packet is delivered.
167 pkt
->finishTime
= tickNextIdle
;
170 /** Function called by the port when the bus is receiving a Timing
173 Bus::recvTiming(PacketPtr pkt
)
175 short src
= pkt
->getSrc();
176 DPRINTF(Bus
, "recvTiming: packet src %d dest %d addr 0x%x cmd %s\n",
177 src
, pkt
->getDest(), pkt
->getAddr(), pkt
->cmdString());
179 BusPort
*src_port
= (src
== defaultId
) ? defaultPort
: interfaces
[src
];
181 // If the bus is busy, or other devices are in line ahead of the current
182 // one, put this device on the retry list.
183 if (!(pkt
->isResponse() || pkt
->isExpressSnoop()) &&
184 (tickNextIdle
> curTick
||
185 (retryList
.size() && (!inRetry
|| src_port
!= retryList
.front()))))
187 addToRetryList(src_port
);
188 DPRINTF(Bus
, "recvTiming: Bus is busy, returning false\n");
194 short dest
= pkt
->getDest();
198 if (dest
== Packet::Broadcast
) {
199 dest_port_id
= findPort(pkt
->getAddr());
200 dest_port
= interfaces
[dest_port_id
];
201 for (SnoopIter s_iter
= snoopPorts
.begin();
202 s_iter
!= snoopPorts
.end();
204 BusPort
*p
= *s_iter
;
205 if (p
!= dest_port
&& p
!= src_port
) {
207 // cache is not allowed to refuse snoop
208 bool success
= p
->sendTiming(pkt
);
211 // avoid unused variable warning
217 assert(dest
>= 0 && dest
< maxId
);
218 assert(dest
!= src
); // catch infinite loops
220 dest_port
= interfaces
[dest_port_id
];
223 if (dest_port_id
== src
) {
224 // Must be forwarded snoop up from below...
225 assert(dest
== Packet::Broadcast
);
227 // send to actual target
228 if (!dest_port
->sendTiming(pkt
)) {
229 // Packet not successfully sent. Leave or put it on the retry list.
230 // illegal to block responses... can lead to deadlock
231 assert(!pkt
->isResponse());
232 DPRINTF(Bus
, "Adding2 a retry to RETRY list %d\n", src
);
233 addToRetryList(src_port
);
236 // send OK, fall through
239 // Packet was successfully sent.
240 // Also take care of retries
242 DPRINTF(Bus
, "Remove retry from list %d\n", src
);
243 retryList
.front()->onRetryList(false);
244 retryList
.pop_front();
251 Bus::recvRetry(int id
)
253 // If there's anything waiting, and the bus isn't busy...
254 if (retryList
.size() && curTick
>= tickNextIdle
) {
255 //retryingPort = retryList.front();
257 DPRINTF(Bus
, "Sending a retry to %s\n", retryList
.front()->getPeer()->name());
258 retryList
.front()->sendRetry();
259 // If inRetry is still true, sendTiming wasn't called
262 retryList
.front()->onRetryList(false);
263 retryList
.pop_front();
266 //Bring tickNextIdle up to the present
267 while (tickNextIdle
< curTick
)
268 tickNextIdle
+= clock
;
270 //Burn a cycle for the missed grant.
271 tickNextIdle
+= clock
;
273 busIdle
.reschedule(tickNextIdle
, true);
276 //If we weren't able to drain before, we might be able to now.
277 if (drainEvent
&& retryList
.size() == 0 && curTick
>= tickNextIdle
) {
278 drainEvent
->process();
279 // Clear the drain event once we're done with it.
285 Bus::findPort(Addr addr
)
287 /* An interval tree would be a better way to do this. --ali. */
290 PortIter i
= portMap
.find(RangeSize(addr
,1));
291 if (i
!= portMap
.end())
294 // Check if this matches the default range
296 for (AddrRangeIter iter
= defaultRange
.begin();
297 iter
!= defaultRange
.end(); iter
++) {
299 DPRINTF(Bus
, " found addr %#llx on default\n", addr
);
305 panic("Unable to find destination for addr (user set default "
306 "responder): %#llx", addr
);
308 DPRINTF(Bus
, "Unable to find destination for addr: %#llx, will use "
309 "default port", addr
);
319 /** Function called by the port when the bus is receiving a Atomic
322 Bus::recvAtomic(PacketPtr pkt
)
324 DPRINTF(Bus
, "recvAtomic: packet src %d dest %d addr 0x%x cmd %s\n",
325 pkt
->getSrc(), pkt
->getDest(), pkt
->getAddr(), pkt
->cmdString());
326 assert(pkt
->getDest() == Packet::Broadcast
);
327 assert(pkt
->isRequest());
329 // Variables for recording original command and snoop response (if
330 // any)... if a snooper respondes, we will need to restore
331 // original command so that additional snoops can take place
333 MemCmd orig_cmd
= pkt
->cmd
;
334 MemCmd snoop_response_cmd
= MemCmd::InvalidCmd
;
335 Tick snoop_response_latency
= 0;
336 int orig_src
= pkt
->getSrc();
338 int target_port_id
= findPort(pkt
->getAddr());
339 Port
*target_port
= interfaces
[target_port_id
];
341 SnoopIter s_end
= snoopPorts
.end();
342 for (SnoopIter s_iter
= snoopPorts
.begin(); s_iter
!= s_end
; s_iter
++) {
343 BusPort
*p
= *s_iter
;
344 // same port should not have both target addresses and snooping
345 assert(p
!= target_port
);
346 if (p
->getId() != pkt
->getSrc()) {
347 Tick latency
= p
->sendAtomic(pkt
);
348 if (pkt
->isResponse()) {
349 // response from snoop agent
350 assert(pkt
->cmd
!= orig_cmd
);
351 assert(pkt
->memInhibitAsserted());
352 // should only happen once
353 assert(snoop_response_cmd
== MemCmd::InvalidCmd
);
354 // save response state
355 snoop_response_cmd
= pkt
->cmd
;
356 snoop_response_latency
= latency
;
357 // restore original packet state for remaining snoopers
359 pkt
->setSrc(orig_src
);
360 pkt
->setDest(Packet::Broadcast
);
365 Tick response_latency
= 0;
367 // we can get requests sent up from the memory side of the bus for
368 // snooping... don't send them back down!
369 if (target_port_id
!= pkt
->getSrc()) {
370 response_latency
= target_port
->sendAtomic(pkt
);
373 // if we got a response from a snooper, restore it here
374 if (snoop_response_cmd
!= MemCmd::InvalidCmd
) {
375 // no one else should have responded
376 assert(!pkt
->isResponse());
377 assert(pkt
->cmd
== orig_cmd
);
378 pkt
->cmd
= snoop_response_cmd
;
379 response_latency
= snoop_response_latency
;
382 // why do we have this packet field and the return value both???
383 pkt
->finishTime
= curTick
+ response_latency
;
384 return response_latency
;
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
);
396 int port_id
= findPort(pkt
->getAddr());
397 Port
*port
= interfaces
[port_id
];
398 // The packet may be changed by another bus on snoops, restore the
400 int src_id
= pkt
->getSrc();
402 assert(pkt
->isRequest()); // hasn't already been satisfied
404 for (SnoopIter s_iter
= snoopPorts
.begin();
405 s_iter
!= snoopPorts
.end();
407 BusPort
*p
= *s_iter
;
408 if (p
!= port
&& p
->getId() != src_id
) {
409 p
->sendFunctional(pkt
);
411 if (pkt
->isResponse()) {
417 // If the snooping hasn't found what we were looking for, keep going.
418 if (!pkt
->isResponse() && port_id
!= pkt
->getSrc()) {
419 port
->sendFunctional(pkt
);
423 /** Function called by the port when the bus is receiving a status change.*/
425 Bus::recvStatusChange(Port::Status status
, int id
)
427 AddrRangeList ranges
;
431 assert(status
== Port::RangeChange
&&
432 "The other statuses need to be implemented.");
434 DPRINTF(BusAddrRanges
, "received RangeChange from device id %d\n", id
);
436 if (id
== defaultId
) {
437 defaultRange
.clear();
438 // Only try to update these ranges if the user set a default responder.
440 defaultPort
->getPeerAddressRanges(ranges
, snoops
);
441 assert(snoops
== false);
442 for(iter
= ranges
.begin(); iter
!= ranges
.end(); iter
++) {
443 defaultRange
.push_back(*iter
);
444 DPRINTF(BusAddrRanges
, "Adding range %#llx - %#llx for default range\n",
445 iter
->start
, iter
->end
);
450 assert((id
< maxId
&& id
>= 0) || id
== defaultId
);
451 BusPort
*port
= interfaces
[id
];
453 // Clean out any previously existent ids
454 for (PortIter portIter
= portMap
.begin();
455 portIter
!= portMap
.end(); ) {
456 if (portIter
->second
== id
)
457 portMap
.erase(portIter
++);
462 for (SnoopIter s_iter
= snoopPorts
.begin();
463 s_iter
!= snoopPorts
.end(); ) {
464 if ((*s_iter
)->getId() == id
)
465 s_iter
= snoopPorts
.erase(s_iter
);
470 port
->getPeerAddressRanges(ranges
, snoops
);
473 DPRINTF(BusAddrRanges
, "Adding id %d to snoop list\n", id
);
474 snoopPorts
.push_back(port
);
477 for (iter
= ranges
.begin(); iter
!= ranges
.end(); iter
++) {
478 DPRINTF(BusAddrRanges
, "Adding range %#llx - %#llx for id %d\n",
479 iter
->start
, iter
->end
, id
);
480 if (portMap
.insert(*iter
, id
) == portMap
.end())
481 panic("Two devices with same range\n");
485 DPRINTF(MMU
, "port list has %d entries\n", portMap
.size());
487 // tell all our peers that our address range has changed.
488 // Don't tell the device that caused this change, it already knows
489 m5::hash_map
<short,BusPort
*>::iterator intIter
;
491 for (intIter
= interfaces
.begin(); intIter
!= interfaces
.end(); intIter
++)
492 if (intIter
->first
!= id
&& intIter
->first
!= funcPortId
)
493 intIter
->second
->sendStatusChange(Port::RangeChange
);
495 if (id
!= defaultId
&& defaultPort
)
496 defaultPort
->sendStatusChange(Port::RangeChange
);
500 Bus::addressRanges(AddrRangeList
&resp
, bool &snoop
, int id
)
505 DPRINTF(BusAddrRanges
, "received address range request, returning:\n");
507 for (AddrRangeIter dflt_iter
= defaultRange
.begin();
508 dflt_iter
!= defaultRange
.end(); dflt_iter
++) {
509 resp
.push_back(*dflt_iter
);
510 DPRINTF(BusAddrRanges
, " -- Dflt: %#llx : %#llx\n",dflt_iter
->start
,
513 for (PortIter portIter
= portMap
.begin();
514 portIter
!= portMap
.end(); portIter
++) {
516 for (AddrRangeIter dflt_iter
= defaultRange
.begin();
517 dflt_iter
!= defaultRange
.end(); dflt_iter
++) {
518 if ((portIter
->first
.start
< dflt_iter
->start
&&
519 portIter
->first
.end
>= dflt_iter
->start
) ||
520 (portIter
->first
.start
< dflt_iter
->end
&&
521 portIter
->first
.end
>= dflt_iter
->end
))
522 fatal("Devices can not set ranges that itersect the default set\
523 but are not a subset of the default set.\n");
524 if (portIter
->first
.start
>= dflt_iter
->start
&&
525 portIter
->first
.end
<= dflt_iter
->end
) {
527 DPRINTF(BusAddrRanges
, " -- %#llx : %#llx is a SUBSET\n",
528 portIter
->first
.start
, portIter
->first
.end
);
531 if (portIter
->second
!= id
&& !subset
) {
532 resp
.push_back(portIter
->first
);
533 DPRINTF(BusAddrRanges
, " -- %#llx : %#llx\n",
534 portIter
->first
.start
, portIter
->first
.end
);
538 for (SnoopIter s_iter
= snoopPorts
.begin(); s_iter
!= snoopPorts
.end();
540 if ((*s_iter
)->getId() != id
) {
548 Bus::findBlockSize(int id
)
550 if (cachedBlockSizeValid
)
551 return cachedBlockSize
;
555 for (PortIter portIter
= portMap
.begin();
556 portIter
!= portMap
.end(); portIter
++) {
557 int tmp_bs
= interfaces
[portIter
->second
]->peerBlockSize();
561 for (SnoopIter s_iter
= snoopPorts
.begin();
562 s_iter
!= snoopPorts
.end(); s_iter
++) {
563 int tmp_bs
= (*s_iter
)->peerBlockSize();
568 max_bs
= defaultBlockSize
;
571 warn_once("Blocksize found to not be 64... hmm... probably not.\n");
572 cachedBlockSize
= max_bs
;
573 cachedBlockSizeValid
= true;
579 Bus::drain(Event
* de
)
581 //We should check that we're not "doing" anything, and that noone is
582 //waiting. We might be idle but have someone waiting if the device we
583 //contacted for a retry didn't actually retry.
584 if (curTick
>= tickNextIdle
&& retryList
.size() == 0) {
595 if (tickNextIdle
< curTick
)
596 tickNextIdle
= (curTick
/ clock
) * clock
+ clock
;
599 BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bus
)
604 Param
<bool> responder_set
;
605 Param
<int> block_size
;
607 END_DECLARE_SIM_OBJECT_PARAMS(Bus
)
609 BEGIN_INIT_SIM_OBJECT_PARAMS(Bus
)
610 INIT_PARAM(bus_id
, "a globally unique bus id"),
611 INIT_PARAM(clock
, "bus clock speed"),
612 INIT_PARAM(width
, "width of the bus (bits)"),
613 INIT_PARAM(responder_set
, "Is a default responder set by the user"),
614 INIT_PARAM(block_size
, "Default blocksize if no device has one")
615 END_INIT_SIM_OBJECT_PARAMS(Bus
)
617 CREATE_SIM_OBJECT(Bus
)
619 return new Bus(getInstanceName(), bus_id
, clock
, width
, responder_set
,
623 REGISTER_SIM_OBJECT("Bus", Bus
)