3 * Copyright (c) 2006 The Regents of The University of Michigan
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15 * this software without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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35 * Definition of a simple bus bridge without buffering.
40 #include "base/range_ops.hh"
41 #include "base/trace.hh"
42 #include "mem/bridge.hh"
43 #include "params/Bridge.hh"
45 Bridge::BridgePort::BridgePort(const std::string
&_name
,
46 Bridge
*_bridge
, BridgePort
*_otherPort
,
47 int _delay
, int _nack_delay
, int _req_limit
,
49 std::vector
<Range
<Addr
> > filter_ranges
)
50 : Port(_name
, _bridge
), bridge(_bridge
), otherPort(_otherPort
),
51 delay(_delay
), nackDelay(_nack_delay
), filterRanges(filter_ranges
),
52 outstandingResponses(0), queuedRequests(0), inRetry(false),
53 reqQueueLimit(_req_limit
), respQueueLimit(_resp_limit
), sendEvent(this)
57 Bridge::Bridge(Params
*p
)
59 portA(p
->name
+ "-portA", this, &portB
, p
->delay
, p
->nack_delay
,
60 p
->req_size_a
, p
->resp_size_a
, p
->filter_ranges_a
),
61 portB(p
->name
+ "-portB", this, &portA
, p
->delay
, p
->nack_delay
,
62 p
->req_size_b
, p
->resp_size_b
, p
->filter_ranges_b
),
63 ackWrites(p
->write_ack
), _params(p
)
66 panic("No support for acknowledging writes\n");
70 Bridge::getPort(const std::string
&if_name
, int idx
)
74 if (if_name
== "side_a")
76 else if (if_name
== "side_b")
81 if (port
->getPeer() != NULL
&& !port
->getPeer()->isDefaultPort())
82 panic("bridge side %s already connected to %s.",
83 if_name
, port
->getPeer()->name());
91 // Make sure that both sides are connected to.
92 if (!portA
.isConnected() || !portB
.isConnected())
93 fatal("Both ports of bus bridge are not connected to a bus.\n");
95 if (portA
.peerBlockSize() != portB
.peerBlockSize())
96 fatal("Busses don't have the same block size... Not supported.\n");
100 Bridge::BridgePort::respQueueFull()
102 assert(outstandingResponses
>= 0 && outstandingResponses
<= respQueueLimit
);
103 return outstandingResponses
>= respQueueLimit
;
107 Bridge::BridgePort::reqQueueFull()
109 assert(queuedRequests
>= 0 && queuedRequests
<= reqQueueLimit
);
110 return queuedRequests
>= reqQueueLimit
;
113 /** Function called by the port when the bus is receiving a Timing
116 Bridge::BridgePort::recvTiming(PacketPtr pkt
)
118 DPRINTF(BusBridge
, "recvTiming: src %d dest %d addr 0x%x\n",
119 pkt
->getSrc(), pkt
->getDest(), pkt
->getAddr());
121 DPRINTF(BusBridge
, "Local queue size: %d outreq: %d outresp: %d\n",
122 sendQueue
.size(), queuedRequests
, outstandingResponses
);
123 DPRINTF(BusBridge
, "Remote queue size: %d outreq: %d outresp: %d\n",
124 otherPort
->sendQueue
.size(), otherPort
->queuedRequests
,
125 otherPort
->outstandingResponses
);
127 if (pkt
->isRequest() && otherPort
->reqQueueFull()) {
128 DPRINTF(BusBridge
, "Remote queue full, nacking\n");
133 if (pkt
->needsResponse()) {
134 if (respQueueFull()) {
135 DPRINTF(BusBridge
, "Local queue full, no space for response, nacking\n");
136 DPRINTF(BusBridge
, "queue size: %d outreq: %d outstanding resp: %d\n",
137 sendQueue
.size(), queuedRequests
, outstandingResponses
);
141 DPRINTF(BusBridge
, "Request Needs response, reserving space\n");
142 ++outstandingResponses
;
146 otherPort
->queueForSendTiming(pkt
);
152 Bridge::BridgePort::nackRequest(PacketPtr pkt
)
155 pkt
->makeTimingResponse();
158 //put it on the list to send
159 Tick readyTime
= curTick
+ nackDelay
;
160 PacketBuffer
*buf
= new PacketBuffer(pkt
, readyTime
, true);
162 // nothing on the list, add it and we're done
163 if (sendQueue
.empty()) {
164 assert(!sendEvent
.scheduled());
165 schedule(sendEvent
, readyTime
);
166 sendQueue
.push_back(buf
);
170 assert(sendEvent
.scheduled() || inRetry
);
172 // does it go at the end?
173 if (readyTime
>= sendQueue
.back()->ready
) {
174 sendQueue
.push_back(buf
);
178 // ok, somewhere in the middle, fun
179 std::list
<PacketBuffer
*>::iterator i
= sendQueue
.begin();
180 std::list
<PacketBuffer
*>::iterator end
= sendQueue
.end();
181 std::list
<PacketBuffer
*>::iterator begin
= sendQueue
.begin();
184 while (i
!= end
&& !done
) {
185 if (readyTime
< (*i
)->ready
) {
187 reschedule(sendEvent
, readyTime
);
188 sendQueue
.insert(i
,buf
);
198 Bridge::BridgePort::queueForSendTiming(PacketPtr pkt
)
200 if (pkt
->isResponse()) {
201 // This is a response for a request we forwarded earlier. The
202 // corresponding PacketBuffer should be stored in the packet's
203 // senderState field.
205 PacketBuffer
*buf
= dynamic_cast<PacketBuffer
*>(pkt
->senderState
);
207 // set up new packet dest & senderState based on values saved
208 // from original request
209 buf
->fixResponse(pkt
);
211 DPRINTF(BusBridge
, "response, new dest %d\n", pkt
->getDest());
216 if (pkt
->isRequest()) {
222 Tick readyTime
= curTick
+ delay
;
223 PacketBuffer
*buf
= new PacketBuffer(pkt
, readyTime
);
225 // If we're about to put this packet at the head of the queue, we
226 // need to schedule an event to do the transmit. Otherwise there
227 // should already be an event scheduled for sending the head
229 if (sendQueue
.empty()) {
230 schedule(sendEvent
, readyTime
);
232 sendQueue
.push_back(buf
);
236 Bridge::BridgePort::trySend()
238 assert(!sendQueue
.empty());
240 PacketBuffer
*buf
= sendQueue
.front();
242 assert(buf
->ready
<= curTick
);
244 PacketPtr pkt
= buf
->pkt
;
246 DPRINTF(BusBridge
, "trySend: origSrc %d dest %d addr 0x%x\n",
247 buf
->origSrc
, pkt
->getDest(), pkt
->getAddr());
249 bool wasReq
= pkt
->isRequest();
250 bool was_nacked_here
= buf
->nackedHere
;
252 // If the send was successful, make sure sender state was set to NULL
253 // otherwise we could get a NACK back of a packet that didn't expect a
254 // response and we would try to use freed memory.
256 Packet::SenderState
*old_sender_state
= pkt
->senderState
;
257 if (pkt
->isRequest() && !buf
->expectResponse
)
258 pkt
->senderState
= NULL
;
260 if (sendTiming(pkt
)) {
262 sendQueue
.pop_front();
263 buf
->pkt
= NULL
; // we no longer own packet, so it's not safe to look at it
265 if (buf
->expectResponse
) {
266 // Must wait for response
267 DPRINTF(BusBridge
, " successful: awaiting response (%d)\n",
268 outstandingResponses
);
270 // no response expected... deallocate packet buffer now.
271 DPRINTF(BusBridge
, " successful: no response expected\n");
277 else if (!was_nacked_here
)
278 --outstandingResponses
;
280 // If there are more packets to send, schedule event to try again.
281 if (!sendQueue
.empty()) {
282 buf
= sendQueue
.front();
283 DPRINTF(BusBridge
, "Scheduling next send\n");
284 schedule(sendEvent
, std::max(buf
->ready
, curTick
+ 1));
287 DPRINTF(BusBridge
, " unsuccessful\n");
288 pkt
->senderState
= old_sender_state
;
292 DPRINTF(BusBridge
, "trySend: queue size: %d outreq: %d outstanding resp: %d\n",
293 sendQueue
.size(), queuedRequests
, outstandingResponses
);
298 Bridge::BridgePort::recvRetry()
301 Tick nextReady
= sendQueue
.front()->ready
;
302 if (nextReady
<= curTick
)
305 schedule(sendEvent
, nextReady
);
308 /** Function called by the port when the bus is receiving a Atomic
311 Bridge::BridgePort::recvAtomic(PacketPtr pkt
)
313 return delay
+ otherPort
->sendAtomic(pkt
);
316 /** Function called by the port when the bus is receiving a Functional
319 Bridge::BridgePort::recvFunctional(PacketPtr pkt
)
321 std::list
<PacketBuffer
*>::iterator i
;
323 pkt
->pushLabel(name());
325 for (i
= sendQueue
.begin(); i
!= sendQueue
.end(); ++i
) {
326 if (pkt
->checkFunctional((*i
)->pkt
))
332 // fall through if pkt still not satisfied
333 otherPort
->sendFunctional(pkt
);
336 /** Function called by the port when the bus is receiving a status change.*/
338 Bridge::BridgePort::recvStatusChange(Port::Status status
)
340 otherPort
->sendStatusChange(status
);
344 Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList
&resp
,
347 otherPort
->getPeerAddressRanges(resp
, snoop
);
348 FilterRangeList(filterRanges
, resp
);
349 // we don't allow snooping across bridges
354 BridgeParams::create()
356 return new Bridge(this);