bridge.cc revision 4986
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/range_ops.hh" 41#include "base/trace.hh" 42#include "mem/bridge.hh" 43#include "params/Bridge.hh" 44 45Bridge::BridgePort::BridgePort(const std::string &_name, 46 Bridge *_bridge, BridgePort *_otherPort, 47 int _delay, int _nack_delay, int _req_limit, 48 int _resp_limit, 49 std::vector<Range<Addr> > filter_ranges) 50 : Port(_name), 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) 54{ 55} 56 57Bridge::Bridge(Params *p) 58 : MemObject(p->name), 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) 64{ 65 if (ackWrites) 66 panic("No support for acknowledging writes\n"); 67} 68 69Port * 70Bridge::getPort(const std::string &if_name, int idx) 71{ 72 BridgePort *port; 73 74 if (if_name == "side_a") 75 port = &portA; 76 else if (if_name == "side_b") 77 port = &portB; 78 else 79 return NULL; 80 81 if (port->getPeer() != NULL) 82 panic("bridge side %s already connected to.", if_name); 83 return port; 84} 85 86 87void 88Bridge::init() 89{ 90 // Make sure that both sides are connected to. 91 if (portA.getPeer() == NULL || portB.getPeer() == NULL) 92 fatal("Both ports of bus bridge are not connected to a bus.\n"); 93 94 if (portA.peerBlockSize() != portB.peerBlockSize()) 95 fatal("Busses don't have the same block size... Not supported.\n"); 96} 97 98bool 99Bridge::BridgePort::respQueueFull() 100{ 101 assert(outstandingResponses >= 0 && outstandingResponses <= respQueueLimit); 102 return outstandingResponses >= respQueueLimit; 103} 104 105bool 106Bridge::BridgePort::reqQueueFull() 107{ 108 assert(queuedRequests >= 0 && queuedRequests <= reqQueueLimit); 109 return queuedRequests >= reqQueueLimit; 110} 111 112/** Function called by the port when the bus is receiving a Timing 113 * transaction.*/ 114bool 115Bridge::BridgePort::recvTiming(PacketPtr pkt) 116{ 117 DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n", 118 pkt->getSrc(), pkt->getDest(), pkt->getAddr()); 119 120 DPRINTF(BusBridge, "Local queue size: %d outreq: %d outresp: %d\n", 121 sendQueue.size(), queuedRequests, outstandingResponses); 122 DPRINTF(BusBridge, "Remote queue size: %d outreq: %d outresp: %d\n", 123 otherPort->sendQueue.size(), otherPort->queuedRequests, 124 otherPort->outstandingResponses); 125 126 if (pkt->isRequest() && otherPort->reqQueueFull()) { 127 DPRINTF(BusBridge, "Remote queue full, nacking\n"); 128 nackRequest(pkt); 129 return true; 130 } 131 132 if (pkt->needsResponse()) 133 if (respQueueFull()) { 134 DPRINTF(BusBridge, "Local queue full, no space for response, nacking\n"); 135 DPRINTF(BusBridge, "queue size: %d outreq: %d outstanding resp: %d\n", 136 sendQueue.size(), queuedRequests, outstandingResponses); 137 nackRequest(pkt); 138 return true; 139 } else { 140 DPRINTF(BusBridge, "Request Needs response, reserving space\n"); 141 ++outstandingResponses; 142 } 143 144 otherPort->queueForSendTiming(pkt); 145 146 return true; 147} 148 149void 150Bridge::BridgePort::nackRequest(PacketPtr pkt) 151{ 152 // Nack the packet 153 pkt->makeTimingResponse(); 154 pkt->setNacked(); 155 156 //put it on the list to send 157 Tick readyTime = curTick + nackDelay; 158 PacketBuffer *buf = new PacketBuffer(pkt, readyTime, true); 159 160 // nothing on the list, add it and we're done 161 if (sendQueue.empty()) { 162 assert(!sendEvent.scheduled()); 163 sendEvent.schedule(readyTime); 164 sendQueue.push_back(buf); 165 return; 166 } 167 168 assert(sendEvent.scheduled() || inRetry); 169 170 // does it go at the end? 171 if (readyTime >= sendQueue.back()->ready) { 172 sendQueue.push_back(buf); 173 return; 174 } 175 176 // ok, somewhere in the middle, fun 177 std::list<PacketBuffer*>::iterator i = sendQueue.begin(); 178 std::list<PacketBuffer*>::iterator end = sendQueue.end(); 179 std::list<PacketBuffer*>::iterator begin = sendQueue.begin(); 180 bool done = false; 181 182 while (i != end && !done) { 183 if (readyTime < (*i)->ready) { 184 if (i == begin) 185 sendEvent.reschedule(readyTime); 186 sendQueue.insert(i,buf); 187 done = true; 188 } 189 i++; 190 } 191 assert(done); 192} 193 194 195void 196Bridge::BridgePort::queueForSendTiming(PacketPtr pkt) 197{ 198 if (pkt->isResponse()) { 199 // This is a response for a request we forwarded earlier. The 200 // corresponding PacketBuffer should be stored in the packet's 201 // senderState field. 202 203 PacketBuffer *buf = dynamic_cast<PacketBuffer*>(pkt->senderState); 204 assert(buf != NULL); 205 // set up new packet dest & senderState based on values saved 206 // from original request 207 buf->fixResponse(pkt); 208 209 DPRINTF(BusBridge, "response, new dest %d\n", pkt->getDest()); 210 delete buf; 211 } 212 213 214 if (pkt->isRequest()) { 215 ++queuedRequests; 216 } 217 218 219 220 Tick readyTime = curTick + delay; 221 PacketBuffer *buf = new PacketBuffer(pkt, readyTime); 222 223 // If we're about to put this packet at the head of the queue, we 224 // need to schedule an event to do the transmit. Otherwise there 225 // should already be an event scheduled for sending the head 226 // packet. 227 if (sendQueue.empty()) { 228 sendEvent.schedule(readyTime); 229 } 230 sendQueue.push_back(buf); 231} 232 233void 234Bridge::BridgePort::trySend() 235{ 236 assert(!sendQueue.empty()); 237 238 PacketBuffer *buf = sendQueue.front(); 239 240 assert(buf->ready <= curTick); 241 242 PacketPtr pkt = buf->pkt; 243 244 DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n", 245 buf->origSrc, pkt->getDest(), pkt->getAddr()); 246 247 bool wasReq = pkt->isRequest(); 248 bool was_nacked_here = buf->nackedHere; 249 250 // If the send was successful, make sure sender state was set to NULL 251 // otherwise we could get a NACK back of a packet that didn't expect a 252 // response and we would try to use freed memory. 253 254 Packet::SenderState *old_sender_state = pkt->senderState; 255 if (pkt->isRequest() && !buf->expectResponse) 256 pkt->senderState = NULL; 257 258 if (sendTiming(pkt)) { 259 // send successful 260 sendQueue.pop_front(); 261 buf->pkt = NULL; // we no longer own packet, so it's not safe to look at it 262 263 if (buf->expectResponse) { 264 // Must wait for response 265 DPRINTF(BusBridge, " successful: awaiting response (%d)\n", 266 outstandingResponses); 267 } else { 268 // no response expected... deallocate packet buffer now. 269 DPRINTF(BusBridge, " successful: no response expected\n"); 270 delete buf; 271 } 272 273 if (wasReq) 274 --queuedRequests; 275 else if (!was_nacked_here) 276 --outstandingResponses; 277 278 // If there are more packets to send, schedule event to try again. 279 if (!sendQueue.empty()) { 280 buf = sendQueue.front(); 281 DPRINTF(BusBridge, "Scheduling next send\n"); 282 sendEvent.schedule(std::max(buf->ready, curTick + 1)); 283 } 284 } else { 285 DPRINTF(BusBridge, " unsuccessful\n"); 286 pkt->senderState = old_sender_state; 287 inRetry = true; 288 } 289 290 DPRINTF(BusBridge, "trySend: queue size: %d outreq: %d outstanding resp: %d\n", 291 sendQueue.size(), queuedRequests, outstandingResponses); 292} 293 294 295void 296Bridge::BridgePort::recvRetry() 297{ 298 inRetry = false; 299 Tick nextReady = sendQueue.front()->ready; 300 if (nextReady <= curTick) 301 trySend(); 302 else 303 sendEvent.schedule(nextReady); 304} 305 306/** Function called by the port when the bus is receiving a Atomic 307 * transaction.*/ 308Tick 309Bridge::BridgePort::recvAtomic(PacketPtr pkt) 310{ 311 return delay + otherPort->sendAtomic(pkt); 312} 313 314/** Function called by the port when the bus is receiving a Functional 315 * transaction.*/ 316void 317Bridge::BridgePort::recvFunctional(PacketPtr pkt) 318{ 319 std::list<PacketBuffer*>::iterator i; 320 321 for (i = sendQueue.begin(); i != sendQueue.end(); ++i) { 322 if (pkt->checkFunctional((*i)->pkt)) 323 return; 324 } 325 326 // fall through if pkt still not satisfied 327 otherPort->sendFunctional(pkt); 328} 329 330/** Function called by the port when the bus is receiving a status change.*/ 331void 332Bridge::BridgePort::recvStatusChange(Port::Status status) 333{ 334 otherPort->sendStatusChange(status); 335} 336 337void 338Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList &resp, 339 bool &snoop) 340{ 341 otherPort->getPeerAddressRanges(resp, snoop); 342 FilterRangeList(filterRanges, resp); 343 // we don't allow snooping across bridges 344 snoop = false; 345} 346 347Bridge * 348BridgeParams::create() 349{ 350 return new Bridge(this); 351} 352