1 2/* 3 * Copyright (c) 2006 The Regents of The University of Michigan 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions are 8 * met: redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer; 10 * redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution; 13 * neither the name of the copyright holders nor the names of its 14 * contributors may be used to endorse or promote products derived from 15 * this software without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 18 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 19 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 20 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 21 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 22 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 23 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 27 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 * 29 * Authors: Ali Saidi 30 * Steve Reinhardt 31 */ 32 33/** 34 * @file 35 * Definition of a simple bus bridge without buffering. 36 */ 37 38#include <algorithm> 39 40#include "base/trace.hh" 41#include "mem/bridge.hh" 42#include "sim/builder.hh" 43 44Bridge::BridgePort::BridgePort(const std::string &_name, 45 Bridge *_bridge, BridgePort *_otherPort, 46 int _delay, int _nack_delay, int _req_limit, 47 int _resp_limit, bool fix_partial_write) 48 : Port(_name), bridge(_bridge), otherPort(_otherPort), 49 delay(_delay), nackDelay(_nack_delay), fixPartialWrite(fix_partial_write), 50 outstandingResponses(0), queuedRequests(0), inRetry(false), 51 reqQueueLimit(_req_limit), respQueueLimit(_resp_limit), sendEvent(this) 52{ 53} 54 55Bridge::Bridge(Params *p) 56 : MemObject(p->name), 57 portA(p->name + "-portA", this, &portB, p->delay, p->nack_delay, 58 p->req_size_a, p->resp_size_a, p->fix_partial_write_a), 59 portB(p->name + "-portB", this, &portA, p->delay, p->nack_delay, 60 p->req_size_b, p->resp_size_b, p->fix_partial_write_b), 61 ackWrites(p->write_ack), _params(p) 62{ 63 if (ackWrites) 64 panic("No support for acknowledging writes\n"); 65} 66 67Port * 68Bridge::getPort(const std::string &if_name, int idx) 69{ 70 BridgePort *port; 71 72 if (if_name == "side_a") 73 port = &portA; 74 else if (if_name == "side_b") 75 port = &portB; 76 else 77 return NULL; 78 79 if (port->getPeer() != NULL) 80 panic("bridge side %s already connected to.", if_name); 81 return port; 82} 83 84 85void 86Bridge::init() 87{ 88 // Make sure that both sides are connected to. 89 if (portA.getPeer() == NULL || portB.getPeer() == NULL) 90 fatal("Both ports of bus bridge are not connected to a bus.\n"); 91 92 if (portA.peerBlockSize() != portB.peerBlockSize()) 93 fatal("Busses don't have the same block size... Not supported.\n"); 94} 95 96bool 97Bridge::BridgePort::respQueueFull() 98{ 99 assert(outstandingResponses >= 0 && outstandingResponses <= respQueueLimit); 100 return outstandingResponses >= respQueueLimit; 101} 102 103bool 104Bridge::BridgePort::reqQueueFull() 105{ 106 assert(queuedRequests >= 0 && queuedRequests <= reqQueueLimit); 107 return queuedRequests >= reqQueueLimit; 108} 109 110/** Function called by the port when the bus is receiving a Timing 111 * transaction.*/ 112bool 113Bridge::BridgePort::recvTiming(PacketPtr pkt) 114{ 115 DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n", 116 pkt->getSrc(), pkt->getDest(), pkt->getAddr()); 117 118 DPRINTF(BusBridge, "Local queue size: %d outreq: %d outresp: %d\n", 119 sendQueue.size(), queuedRequests, outstandingResponses); 120 DPRINTF(BusBridge, "Remove queue size: %d outreq: %d outresp: %d\n", 121 otherPort->sendQueue.size(), otherPort->queuedRequests, 122 otherPort->outstandingResponses); 123 124 if (pkt->isRequest() && otherPort->reqQueueFull() && !pkt->wasNacked()) { 125 DPRINTF(BusBridge, "Remote queue full, nacking\n"); 126 nackRequest(pkt); 127 return true; 128 } 129 130 if (pkt->needsResponse() && !pkt->wasNacked()) 131 if (respQueueFull()) { 132 DPRINTF(BusBridge, "Local queue full, no space for response, nacking\n"); 133 DPRINTF(BusBridge, "queue size: %d outreq: %d outstanding resp: %d\n", 134 sendQueue.size(), queuedRequests, outstandingResponses); 135 nackRequest(pkt); 136 return true; 137 } else { 138 DPRINTF(BusBridge, "Request Needs response, reserving space\n"); 139 ++outstandingResponses; 140 } 141 142 otherPort->queueForSendTiming(pkt); 143 144 return true; 145} 146 147void 148Bridge::BridgePort::nackRequest(PacketPtr pkt) 149{ 150 // Nack the packet 151 pkt->setNacked(); 152 pkt->setDest(pkt->getSrc()); 153 154 //put it on the list to send 155 Tick readyTime = curTick + nackDelay; 156 PacketBuffer *buf = new PacketBuffer(pkt, readyTime, true); 157 158 // nothing on the list, add it and we're done 159 if (sendQueue.empty()) { 160 assert(!sendEvent.scheduled()); 161 sendEvent.schedule(readyTime); 162 sendQueue.push_back(buf); 163 return; 164 } 165 166 assert(sendEvent.scheduled() || inRetry); 167 168 // does it go at the end? 169 if (readyTime >= sendQueue.back()->ready) { 170 sendQueue.push_back(buf); 171 return; 172 } 173 174 // ok, somewhere in the middle, fun 175 std::list<PacketBuffer*>::iterator i = sendQueue.begin(); 176 std::list<PacketBuffer*>::iterator end = sendQueue.end(); 177 std::list<PacketBuffer*>::iterator begin = sendQueue.begin(); 178 bool done = false; 179 180 while (i != end && !done) { 181 if (readyTime < (*i)->ready) { 182 if (i == begin) 183 sendEvent.reschedule(readyTime); 184 sendQueue.insert(i,buf); 185 done = true; 186 } 187 i++; 188 } 189 assert(done); 190} 191 192 193void 194Bridge::BridgePort::queueForSendTiming(PacketPtr pkt) 195{ 196 if (pkt->isResponse() || pkt->wasNacked()) { 197 // This is a response for a request we forwarded earlier. The 198 // corresponding PacketBuffer should be stored in the packet's 199 // senderState field. 200 PacketBuffer *buf = dynamic_cast<PacketBuffer*>(pkt->senderState); 201 assert(buf != NULL); 202 // set up new packet dest & senderState based on values saved 203 // from original request 204 buf->fixResponse(pkt); 205 206 // Check if this packet was expecting a response and it's a nacked 207 // packet, in which case we will never being seeing it 208 if (buf->expectResponse && pkt->wasNacked()) 209 --outstandingResponses; 210
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224 225 // 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 228 // packet. 229 if (sendQueue.empty()) { 230 sendEvent.schedule(readyTime); 231 } 232 sendQueue.push_back(buf); 233} 234 235void 236Bridge::BridgePort::trySend() 237{ 238 assert(!sendQueue.empty()); 239 240 PacketBuffer *buf = sendQueue.front(); 241 242 assert(buf->ready <= curTick); 243 244 PacketPtr pkt = buf->pkt; 245 246 // Ugly! @todo When multilevel coherence works this will be removed 247 if (pkt->cmd == MemCmd::WriteInvalidateReq && fixPartialWrite && 248 !pkt->wasNacked()) { 249 PacketPtr funcPkt = new Packet(pkt->req, MemCmd::WriteReq, 250 Packet::Broadcast); 251 funcPkt->dataStatic(pkt->getPtr<uint8_t>()); 252 sendFunctional(funcPkt); 253 pkt->cmd = MemCmd::WriteReq; 254 delete funcPkt; 255 } 256 257 DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n", 258 buf->origSrc, pkt->getDest(), pkt->getAddr()); 259 260 bool wasReq = pkt->isRequest(); 261 bool wasNacked = pkt->wasNacked(); 262 263 if (sendTiming(pkt)) { 264 // send successful 265 sendQueue.pop_front(); 266 buf->pkt = NULL; // we no longer own packet, so it's not safe to look at it 267 268 if (buf->expectResponse) { 269 // Must wait for response 270 DPRINTF(BusBridge, " successful: awaiting response (%d)\n", 271 outstandingResponses); 272 } else { 273 // no response expected... deallocate packet buffer now. 274 DPRINTF(BusBridge, " successful: no response expected\n"); 275 delete buf; 276 } 277 278 if (!wasNacked) { 279 if (wasReq) 280 --queuedRequests; 281 else 282 --outstandingResponses; 283 } 284 285 // If there are more packets to send, schedule event to try again. 286 if (!sendQueue.empty()) { 287 buf = sendQueue.front(); 288 DPRINTF(BusBridge, "Scheduling next send\n"); 289 sendEvent.schedule(std::max(buf->ready, curTick + 1)); 290 } 291 } else { 292 DPRINTF(BusBridge, " unsuccessful\n"); 293 inRetry = true; 294 } 295 DPRINTF(BusBridge, "trySend: queue size: %d outreq: %d outstanding resp: %d\n", 296 sendQueue.size(), queuedRequests, outstandingResponses); 297} 298 299 300void 301Bridge::BridgePort::recvRetry() 302{ 303 inRetry = false; 304 Tick nextReady = sendQueue.front()->ready; 305 if (nextReady <= curTick) 306 trySend(); 307 else 308 sendEvent.schedule(nextReady); 309} 310 311/** Function called by the port when the bus is receiving a Atomic 312 * transaction.*/ 313Tick 314Bridge::BridgePort::recvAtomic(PacketPtr pkt) 315{ 316 // fix partial atomic writes... similar to the timing code that does the 317 // same... will be removed once our code gets this right 318 if (pkt->cmd == MemCmd::WriteInvalidateReq && fixPartialWrite) { 319 320 PacketPtr funcPkt = new Packet(pkt->req, MemCmd::WriteReq, 321 Packet::Broadcast); 322 funcPkt->dataStatic(pkt->getPtr<uint8_t>()); 323 otherPort->sendFunctional(funcPkt); 324 delete funcPkt; 325 pkt->cmd = MemCmd::WriteReq; 326 } 327 return delay + otherPort->sendAtomic(pkt); 328} 329 330/** Function called by the port when the bus is receiving a Functional 331 * transaction.*/ 332void 333Bridge::BridgePort::recvFunctional(PacketPtr pkt) 334{ 335 std::list<PacketBuffer*>::iterator i; 336 337 for (i = sendQueue.begin(); i != sendQueue.end(); ++i) { 338 if (pkt->checkFunctional((*i)->pkt)) 339 return; 340 } 341 342 // fall through if pkt still not satisfied 343 otherPort->sendFunctional(pkt); 344} 345 346/** Function called by the port when the bus is receiving a status change.*/ 347void 348Bridge::BridgePort::recvStatusChange(Port::Status status) 349{ 350 otherPort->sendStatusChange(status); 351} 352 353void 354Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList &resp, 355 bool &snoop) 356{ 357 otherPort->getPeerAddressRanges(resp, snoop); 358 // we don't allow snooping across bridges 359 snoop = false; 360} 361 362BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bridge) 363 364 Param<int> req_size_a; 365 Param<int> req_size_b; 366 Param<int> resp_size_a; 367 Param<int> resp_size_b; 368 Param<Tick> delay; 369 Param<Tick> nack_delay; 370 Param<bool> write_ack; 371 Param<bool> fix_partial_write_a; 372 Param<bool> fix_partial_write_b; 373 374END_DECLARE_SIM_OBJECT_PARAMS(Bridge) 375 376BEGIN_INIT_SIM_OBJECT_PARAMS(Bridge) 377 378 INIT_PARAM(req_size_a, "The size of the queue for requests coming into side a"), 379 INIT_PARAM(req_size_b, "The size of the queue for requests coming into side b"), 380 INIT_PARAM(resp_size_a, "The size of the queue for responses coming into side a"), 381 INIT_PARAM(resp_size_b, "The size of the queue for responses coming into side b"), 382 INIT_PARAM(delay, "The miminum delay to cross this bridge"), 383 INIT_PARAM(nack_delay, "The minimum delay to nack a packet"), 384 INIT_PARAM(write_ack, "Acknowledge any writes that are received."), 385 INIT_PARAM(fix_partial_write_a, "Fixup any partial block writes that are received"), 386 INIT_PARAM(fix_partial_write_b, "Fixup any partial block writes that are received") 387 388END_INIT_SIM_OBJECT_PARAMS(Bridge) 389 390CREATE_SIM_OBJECT(Bridge) 391{ 392 Bridge::Params *p = new Bridge::Params; 393 p->name = getInstanceName(); 394 p->req_size_a = req_size_a; 395 p->req_size_b = req_size_b; 396 p->resp_size_a = resp_size_a; 397 p->resp_size_b = resp_size_b; 398 p->delay = delay; 399 p->nack_delay = nack_delay; 400 p->write_ack = write_ack; 401 p->fix_partial_write_a = fix_partial_write_a; 402 p->fix_partial_write_b = fix_partial_write_b; 403 return new Bridge(p); 404} 405 406REGISTER_SIM_OBJECT("Bridge", Bridge) 407 408
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