2 * Copyright (c) 2006 The Regents of The University of Michigan
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14 * this software without specific prior written permission.
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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33 * Definition of a bus object.
39 #include "base/misc.hh"
40 #include "base/trace.hh"
42 #include "params/Bus.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());
91 /** Get the ranges of anyone other buses that we are connected to. */
95 m5::hash_map
<short,BusPort
*>::iterator intIter
;
97 for (intIter
= interfaces
.begin(); intIter
!= interfaces
.end(); intIter
++)
98 intIter
->second
->sendStatusChange(Port::RangeChange
);
101 Bus::BusFreeEvent::BusFreeEvent(Bus
*_bus
) : Event(&mainEventQueue
), bus(_bus
)
104 void Bus::BusFreeEvent::process()
109 const char * Bus::BusFreeEvent::description()
111 return "bus became available";
114 void Bus::occupyBus(PacketPtr pkt
)
116 //Bring tickNextIdle up to the present tick
117 //There is some potential ambiguity where a cycle starts, which might make
118 //a difference when devices are acting right around a cycle boundary. Using
119 //a < allows things which happen exactly on a cycle boundary to take up
120 //only the following cycle. Anything that happens later will have to "wait"
121 //for the end of that cycle, and then start using the bus after that.
122 if (tickNextIdle
< curTick
) {
123 tickNextIdle
= curTick
;
124 if (tickNextIdle
% clock
!= 0)
125 tickNextIdle
= curTick
- (curTick
% clock
) + clock
;
128 // The packet will be sent. Figure out how long it occupies the bus, and
129 // how much of that time is for the first "word", aka bus width.
131 // Requests need one cycle to send an address
132 if (pkt
->isRequest())
134 else if (pkt
->isResponse() || pkt
->hasData()) {
135 // If a packet has data, it needs ceil(size/width) cycles to send it
136 // We're using the "adding instead of dividing" trick again here
137 if (pkt
->hasData()) {
138 int dataSize
= pkt
->getSize();
139 numCycles
+= dataSize
/width
;
140 if (dataSize
% width
)
143 // If the packet didn't have data, it must have been a response.
144 // Those use the bus for one cycle to send their data.
149 // The first word will be delivered after the current tick, the delivery
150 // of the address if any, and one bus cycle to deliver the data
151 pkt
->firstWordTime
= tickNextIdle
+ (pkt
->isRequest() ? clock
: 0) + clock
;
153 //Advance it numCycles bus cycles.
154 //XXX Should this use the repeated addition trick as well?
155 tickNextIdle
+= (numCycles
* clock
);
156 if (!busIdle
.scheduled()) {
157 busIdle
.schedule(tickNextIdle
);
159 busIdle
.reschedule(tickNextIdle
);
161 DPRINTF(Bus
, "The bus is now occupied from tick %d to %d\n",
162 curTick
, tickNextIdle
);
164 // The bus will become idle once the current packet is delivered.
165 pkt
->finishTime
= tickNextIdle
;
168 /** Function called by the port when the bus is receiving a Timing
171 Bus::recvTiming(PacketPtr pkt
)
173 short src
= pkt
->getSrc();
174 DPRINTF(Bus
, "recvTiming: packet src %d dest %d addr 0x%x cmd %s\n",
175 src
, pkt
->getDest(), pkt
->getAddr(), pkt
->cmdString());
178 if (src
== defaultId
)
179 src_port
= defaultPort
;
181 src_port
= checkBusCache(src
);
182 if (src_port
== NULL
) {
183 src_port
= interfaces
[src
];
184 updateBusCache(src
, src_port
);
188 // If the bus is busy, or other devices are in line ahead of the current
189 // one, put this device on the retry list.
190 if (!pkt
->isExpressSnoop() &&
191 (tickNextIdle
> curTick
||
192 (retryList
.size() && (!inRetry
|| src_port
!= retryList
.front()))))
194 addToRetryList(src_port
);
195 DPRINTF(Bus
, "recvTiming: Bus is busy, returning false\n");
199 if (!pkt
->isExpressSnoop()) {
203 short dest
= pkt
->getDest();
207 if (dest
== Packet::Broadcast
) {
208 dest_port_id
= findPort(pkt
->getAddr());
209 dest_port
= (dest_port_id
== defaultId
) ?
210 defaultPort
: interfaces
[dest_port_id
];
211 SnoopIter s_end
= snoopPorts
.end();
212 for (SnoopIter s_iter
= snoopPorts
.begin(); s_iter
!= s_end
; s_iter
++) {
213 BusPort
*p
= *s_iter
;
214 if (p
!= dest_port
&& p
!= src_port
) {
215 // cache is not allowed to refuse snoop
216 bool success M5_VAR_USED
= p
->sendTiming(pkt
);
221 assert(dest
>= 0 && dest
< maxId
);
222 assert(dest
!= src
); // catch infinite loops
224 if (dest_port_id
== defaultId
)
225 dest_port
= defaultPort
;
227 dest_port
= checkBusCache(dest
);
228 if (dest_port
== NULL
) {
229 dest_port
= interfaces
[dest_port_id
];
230 // updateBusCache(dest_port_id, dest_port);
233 dest_port
= (dest_port_id
== defaultId
) ?
234 defaultPort
: interfaces
[dest_port_id
];
237 if (dest_port_id
== src
) {
238 // Must be forwarded snoop up from below...
239 assert(dest
== Packet::Broadcast
);
240 assert(src
!= defaultId
); // catch infinite loops
242 // send to actual target
243 if (!dest_port
->sendTiming(pkt
)) {
244 // Packet not successfully sent. Leave or put it on the retry list.
245 // illegal to block responses... can lead to deadlock
246 assert(!pkt
->isResponse());
247 DPRINTF(Bus
, "Adding2 a retry to RETRY list %d\n", src
);
248 addToRetryList(src_port
);
251 // send OK, fall through
254 // Packet was successfully sent.
255 // Also take care of retries
257 DPRINTF(Bus
, "Remove retry from list %d\n", src
);
258 retryList
.front()->onRetryList(false);
259 retryList
.pop_front();
266 Bus::recvRetry(int id
)
268 // If there's anything waiting, and the bus isn't busy...
269 if (retryList
.size() && curTick
>= tickNextIdle
) {
270 //retryingPort = retryList.front();
272 DPRINTF(Bus
, "Sending a retry to %s\n", retryList
.front()->getPeer()->name());
273 retryList
.front()->sendRetry();
274 // If inRetry is still true, sendTiming wasn't called
277 retryList
.front()->onRetryList(false);
278 retryList
.pop_front();
281 //Bring tickNextIdle up to the present
282 while (tickNextIdle
< curTick
)
283 tickNextIdle
+= clock
;
285 //Burn a cycle for the missed grant.
286 tickNextIdle
+= clock
;
288 busIdle
.reschedule(tickNextIdle
, true);
291 //If we weren't able to drain before, we might be able to now.
292 if (drainEvent
&& retryList
.size() == 0 && curTick
>= tickNextIdle
) {
293 drainEvent
->process();
294 // Clear the drain event once we're done with it.
300 Bus::findPort(Addr addr
)
302 /* An interval tree would be a better way to do this. --ali. */
305 dest_id
= checkPortCache(addr
);
307 PortIter i
= portMap
.find(RangeSize(addr
,1));
308 if (i
!= portMap
.end())
310 updatePortCache(dest_id
, i
->first
.start
, i
->first
.end
);
313 // Check if this matches the default range
315 AddrRangeIter a_end
= defaultRange
.end();
316 for (AddrRangeIter i
= defaultRange
.begin(); i
!= a_end
; i
++) {
318 DPRINTF(Bus
, " found addr %#llx on default\n", addr
);
324 panic("Unable to find destination for addr (user set default "
325 "responder): %#llx", addr
);
327 DPRINTF(Bus
, "Unable to find destination for addr: %#llx, will use "
328 "default port", addr
);
338 /** Function called by the port when the bus is receiving a Atomic
341 Bus::recvAtomic(PacketPtr pkt
)
343 DPRINTF(Bus
, "recvAtomic: packet src %d dest %d addr 0x%x cmd %s\n",
344 pkt
->getSrc(), pkt
->getDest(), pkt
->getAddr(), pkt
->cmdString());
345 assert(pkt
->getDest() == Packet::Broadcast
);
346 assert(pkt
->isRequest());
348 // Variables for recording original command and snoop response (if
349 // any)... if a snooper respondes, we will need to restore
350 // original command so that additional snoops can take place
352 MemCmd orig_cmd
= pkt
->cmd
;
353 MemCmd snoop_response_cmd
= MemCmd::InvalidCmd
;
354 Tick snoop_response_latency
= 0;
355 int orig_src
= pkt
->getSrc();
357 int target_port_id
= findPort(pkt
->getAddr());
358 BusPort
*target_port
;
359 if (target_port_id
== defaultId
)
360 target_port
= defaultPort
;
362 target_port
= checkBusCache(target_port_id
);
363 if (target_port
== NULL
) {
364 target_port
= interfaces
[target_port_id
];
365 updateBusCache(target_port_id
, target_port
);
369 SnoopIter s_end
= snoopPorts
.end();
370 for (SnoopIter s_iter
= snoopPorts
.begin(); s_iter
!= s_end
; s_iter
++) {
371 BusPort
*p
= *s_iter
;
372 // same port should not have both target addresses and snooping
373 assert(p
!= target_port
);
374 if (p
->getId() != pkt
->getSrc()) {
375 Tick latency
= p
->sendAtomic(pkt
);
376 if (pkt
->isResponse()) {
377 // response from snoop agent
378 assert(pkt
->cmd
!= orig_cmd
);
379 assert(pkt
->memInhibitAsserted());
380 // should only happen once
381 assert(snoop_response_cmd
== MemCmd::InvalidCmd
);
382 // save response state
383 snoop_response_cmd
= pkt
->cmd
;
384 snoop_response_latency
= latency
;
385 // restore original packet state for remaining snoopers
387 pkt
->setSrc(orig_src
);
388 pkt
->setDest(Packet::Broadcast
);
393 Tick response_latency
= 0;
395 // we can get requests sent up from the memory side of the bus for
396 // snooping... don't send them back down!
397 if (target_port_id
!= pkt
->getSrc()) {
398 response_latency
= target_port
->sendAtomic(pkt
);
401 // if we got a response from a snooper, restore it here
402 if (snoop_response_cmd
!= MemCmd::InvalidCmd
) {
403 // no one else should have responded
404 assert(!pkt
->isResponse());
405 assert(pkt
->cmd
== orig_cmd
);
406 pkt
->cmd
= snoop_response_cmd
;
407 response_latency
= snoop_response_latency
;
410 // why do we have this packet field and the return value both???
411 pkt
->finishTime
= curTick
+ response_latency
;
412 return response_latency
;
415 /** Function called by the port when the bus is receiving a Functional
418 Bus::recvFunctional(PacketPtr pkt
)
420 DPRINTF(Bus
, "recvFunctional: packet src %d dest %d addr 0x%x cmd %s\n",
421 pkt
->getSrc(), pkt
->getDest(), pkt
->getAddr(), pkt
->cmdString());
422 assert(pkt
->getDest() == Packet::Broadcast
);
424 int port_id
= findPort(pkt
->getAddr());
425 Port
*port
= (port_id
== defaultId
) ? defaultPort
: interfaces
[port_id
];
426 // The packet may be changed by another bus on snoops, restore the
428 int src_id
= pkt
->getSrc();
430 assert(pkt
->isRequest()); // hasn't already been satisfied
432 SnoopIter s_end
= snoopPorts
.end();
433 for (SnoopIter s_iter
= snoopPorts
.begin(); s_iter
!= s_end
; s_iter
++) {
434 BusPort
*p
= *s_iter
;
435 if (p
!= port
&& p
->getId() != src_id
) {
436 p
->sendFunctional(pkt
);
438 if (pkt
->isResponse()) {
444 // If the snooping hasn't found what we were looking for, keep going.
445 if (!pkt
->isResponse() && port_id
!= pkt
->getSrc()) {
446 port
->sendFunctional(pkt
);
450 /** Function called by the port when the bus is receiving a status change.*/
452 Bus::recvStatusChange(Port::Status status
, int id
)
454 AddrRangeList ranges
;
458 if (inRecvStatusChange
.count(id
))
460 inRecvStatusChange
.insert(id
);
462 assert(status
== Port::RangeChange
&&
463 "The other statuses need to be implemented.");
465 DPRINTF(BusAddrRanges
, "received RangeChange from device id %d\n", id
);
468 if (id
== defaultId
) {
469 defaultRange
.clear();
470 // Only try to update these ranges if the user set a default responder.
472 defaultPort
->getPeerAddressRanges(ranges
, snoops
);
473 assert(snoops
== false);
474 for(iter
= ranges
.begin(); iter
!= ranges
.end(); iter
++) {
475 defaultRange
.push_back(*iter
);
476 DPRINTF(BusAddrRanges
, "Adding range %#llx - %#llx for default range\n",
477 iter
->start
, iter
->end
);
482 assert((id
< maxId
&& id
>= 0) || id
== defaultId
);
483 BusPort
*port
= interfaces
[id
];
485 // Clean out any previously existent ids
486 for (PortIter portIter
= portMap
.begin();
487 portIter
!= portMap
.end(); ) {
488 if (portIter
->second
== id
)
489 portMap
.erase(portIter
++);
494 for (SnoopIter s_iter
= snoopPorts
.begin();
495 s_iter
!= snoopPorts
.end(); ) {
496 if ((*s_iter
)->getId() == id
)
497 s_iter
= snoopPorts
.erase(s_iter
);
502 port
->getPeerAddressRanges(ranges
, snoops
);
505 DPRINTF(BusAddrRanges
, "Adding id %d to snoop list\n", id
);
506 snoopPorts
.push_back(port
);
509 for (iter
= ranges
.begin(); iter
!= ranges
.end(); iter
++) {
510 DPRINTF(BusAddrRanges
, "Adding range %#llx - %#llx for id %d\n",
511 iter
->start
, iter
->end
, id
);
512 if (portMap
.insert(*iter
, id
) == portMap
.end())
513 panic("Two devices with same range\n");
517 DPRINTF(MMU
, "port list has %d entries\n", portMap
.size());
519 // tell all our peers that our address range has changed.
520 // Don't tell the device that caused this change, it already knows
521 m5::hash_map
<short,BusPort
*>::iterator intIter
;
523 for (intIter
= interfaces
.begin(); intIter
!= interfaces
.end(); intIter
++)
524 if (intIter
->first
!= id
&& intIter
->first
!= funcPortId
)
525 intIter
->second
->sendStatusChange(Port::RangeChange
);
527 if (id
!= defaultId
&& defaultPort
)
528 defaultPort
->sendStatusChange(Port::RangeChange
);
529 inRecvStatusChange
.erase(id
);
533 Bus::addressRanges(AddrRangeList
&resp
, bool &snoop
, int id
)
538 DPRINTF(BusAddrRanges
, "received address range request, returning:\n");
540 for (AddrRangeIter dflt_iter
= defaultRange
.begin();
541 dflt_iter
!= defaultRange
.end(); dflt_iter
++) {
542 resp
.push_back(*dflt_iter
);
543 DPRINTF(BusAddrRanges
, " -- Dflt: %#llx : %#llx\n",dflt_iter
->start
,
546 for (PortIter portIter
= portMap
.begin();
547 portIter
!= portMap
.end(); portIter
++) {
549 for (AddrRangeIter dflt_iter
= defaultRange
.begin();
550 dflt_iter
!= defaultRange
.end(); dflt_iter
++) {
551 if ((portIter
->first
.start
< dflt_iter
->start
&&
552 portIter
->first
.end
>= dflt_iter
->start
) ||
553 (portIter
->first
.start
< dflt_iter
->end
&&
554 portIter
->first
.end
>= dflt_iter
->end
))
555 fatal("Devices can not set ranges that itersect the default set\
556 but are not a subset of the default set.\n");
557 if (portIter
->first
.start
>= dflt_iter
->start
&&
558 portIter
->first
.end
<= dflt_iter
->end
) {
560 DPRINTF(BusAddrRanges
, " -- %#llx : %#llx is a SUBSET\n",
561 portIter
->first
.start
, portIter
->first
.end
);
564 if (portIter
->second
!= id
&& !subset
) {
565 resp
.push_back(portIter
->first
);
566 DPRINTF(BusAddrRanges
, " -- %#llx : %#llx\n",
567 portIter
->first
.start
, portIter
->first
.end
);
571 for (SnoopIter s_iter
= snoopPorts
.begin(); s_iter
!= snoopPorts
.end();
573 if ((*s_iter
)->getId() != id
) {
581 Bus::findBlockSize(int id
)
583 if (cachedBlockSizeValid
)
584 return cachedBlockSize
;
588 PortIter p_end
= portMap
.end();
589 for (PortIter p_iter
= portMap
.begin(); p_iter
!= p_end
; p_iter
++) {
590 int tmp_bs
= interfaces
[p_iter
->second
]->peerBlockSize();
594 SnoopIter s_end
= snoopPorts
.end();
595 for (SnoopIter s_iter
= snoopPorts
.begin(); s_iter
!= s_end
; s_iter
++) {
596 int tmp_bs
= (*s_iter
)->peerBlockSize();
601 max_bs
= defaultBlockSize
;
604 warn_once("Blocksize found to not be 64... hmm... probably not.\n");
605 cachedBlockSize
= max_bs
;
606 cachedBlockSizeValid
= true;
612 Bus::drain(Event
* de
)
614 //We should check that we're not "doing" anything, and that noone is
615 //waiting. We might be idle but have someone waiting if the device we
616 //contacted for a retry didn't actually retry.
617 if (curTick
>= tickNextIdle
&& retryList
.size() == 0) {
628 if (tickNextIdle
< curTick
)
629 tickNextIdle
= (curTick
/ clock
) * clock
+ clock
;
635 return new Bus(name
, bus_id
, clock
, width
, responder_set
, block_size
);