bridge.hh revision 10405
1/* 2 * Copyright (c) 2011-2013 ARM Limited 3 * All rights reserved 4 * 5 * The license below extends only to copyright in the software and shall 6 * not be construed as granting a license to any other intellectual 7 * property including but not limited to intellectual property relating 8 * to a hardware implementation of the functionality of the software 9 * licensed hereunder. You may use the software subject to the license 10 * terms below provided that you ensure that this notice is replicated 11 * unmodified and in its entirety in all distributions of the software, 12 * modified or unmodified, in source code or in binary form. 13 * 14 * Copyright (c) 2006 The Regents of The University of Michigan 15 * All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions are 19 * met: redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer; 21 * redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution; 24 * neither the name of the copyright holders nor the names of its 25 * contributors may be used to endorse or promote products derived from 26 * this software without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 39 * 40 * Authors: Ali Saidi 41 * Steve Reinhardt 42 * Andreas Hansson 43 */ 44 45/** 46 * @file 47 * Declaration of a memory-mapped bridge that connects a master 48 * and a slave through a request and response queue. 49 */ 50 51#ifndef __MEM_BRIDGE_HH__ 52#define __MEM_BRIDGE_HH__ 53 54#include <deque> 55 56#include "base/types.hh" 57#include "mem/mem_object.hh" 58#include "params/Bridge.hh" 59 60/** 61 * A bridge is used to interface two different crossbars (or in general a 62 * memory-mapped master and slave), with buffering for requests and 63 * responses. The bridge has a fixed delay for packets passing through 64 * it and responds to a fixed set of address ranges. 65 * 66 * The bridge comprises a slave port and a master port, that buffer 67 * outgoing responses and requests respectively. Buffer space is 68 * reserved when a request arrives, also reserving response space 69 * before forwarding the request. If there is no space present, then 70 * the bridge will delay accepting the packet until space becomes 71 * available. 72 */ 73class Bridge : public MemObject 74{ 75 protected: 76 77 /** 78 * A bridge request state stores packets along with their sender 79 * state and original source. It has enough information to also 80 * restore the response once it comes back to the bridge. 81 */ 82 class RequestState : public Packet::SenderState 83 { 84 85 public: 86 87 const PortID origSrc; 88 89 RequestState(PortID orig_src) : origSrc(orig_src) 90 { } 91 92 }; 93 94 /** 95 * A deferred packet stores a packet along with its scheduled 96 * transmission time 97 */ 98 class DeferredPacket 99 { 100 101 public: 102 103 const Tick tick; 104 const PacketPtr pkt; 105 106 DeferredPacket(PacketPtr _pkt, Tick _tick) : tick(_tick), pkt(_pkt) 107 { } 108 }; 109 110 // Forward declaration to allow the slave port to have a pointer 111 class BridgeMasterPort; 112 113 /** 114 * The port on the side that receives requests and sends 115 * responses. The slave port has a set of address ranges that it 116 * is responsible for. The slave port also has a buffer for the 117 * responses not yet sent. 118 */ 119 class BridgeSlavePort : public SlavePort 120 { 121 122 private: 123 124 /** The bridge to which this port belongs. */ 125 Bridge& bridge; 126 127 /** 128 * Master port on the other side of the bridge. 129 */ 130 BridgeMasterPort& masterPort; 131 132 /** Minimum request delay though this bridge. */ 133 const Cycles delay; 134 135 /** Address ranges to pass through the bridge */ 136 const AddrRangeList ranges; 137 138 /** 139 * Response packet queue. Response packets are held in this 140 * queue for a specified delay to model the processing delay 141 * of the bridge. We use a deque as we need to iterate over 142 * the items for functional accesses. 143 */ 144 std::deque<DeferredPacket> transmitList; 145 146 /** Counter to track the outstanding responses. */ 147 unsigned int outstandingResponses; 148 149 /** If we should send a retry when space becomes available. */ 150 bool retryReq; 151 152 /** Max queue size for reserved responses. */ 153 unsigned int respQueueLimit; 154 155 /** 156 * Is this side blocked from accepting new response packets. 157 * 158 * @return true if the reserved space has reached the set limit 159 */ 160 bool respQueueFull() const; 161 162 /** 163 * Handle send event, scheduled when the packet at the head of 164 * the response queue is ready to transmit (for timing 165 * accesses only). 166 */ 167 void trySendTiming(); 168 169 /** Send event for the response queue. */ 170 EventWrapper<BridgeSlavePort, 171 &BridgeSlavePort::trySendTiming> sendEvent; 172 173 public: 174 175 /** 176 * Constructor for the BridgeSlavePort. 177 * 178 * @param _name the port name including the owner 179 * @param _bridge the structural owner 180 * @param _masterPort the master port on the other side of the bridge 181 * @param _delay the delay in cycles from receiving to sending 182 * @param _resp_limit the size of the response queue 183 * @param _ranges a number of address ranges to forward 184 */ 185 BridgeSlavePort(const std::string& _name, Bridge& _bridge, 186 BridgeMasterPort& _masterPort, Cycles _delay, 187 int _resp_limit, std::vector<AddrRange> _ranges); 188 189 /** 190 * Queue a response packet to be sent out later and also schedule 191 * a send if necessary. 192 * 193 * @param pkt a response to send out after a delay 194 * @param when tick when response packet should be sent 195 */ 196 void schedTimingResp(PacketPtr pkt, Tick when); 197 198 /** 199 * Retry any stalled request that we have failed to accept at 200 * an earlier point in time. This call will do nothing if no 201 * request is waiting. 202 */ 203 void retryStalledReq(); 204 205 protected: 206 207 /** When receiving a timing request from the peer port, 208 pass it to the bridge. */ 209 bool recvTimingReq(PacketPtr pkt); 210 211 /** When receiving a retry request from the peer port, 212 pass it to the bridge. */ 213 void recvRetry(); 214 215 /** When receiving a Atomic requestfrom the peer port, 216 pass it to the bridge. */ 217 Tick recvAtomic(PacketPtr pkt); 218 219 /** When receiving a Functional request from the peer port, 220 pass it to the bridge. */ 221 void recvFunctional(PacketPtr pkt); 222 223 /** When receiving a address range request the peer port, 224 pass it to the bridge. */ 225 AddrRangeList getAddrRanges() const; 226 }; 227 228 229 /** 230 * Port on the side that forwards requests and receives 231 * responses. The master port has a buffer for the requests not 232 * yet sent. 233 */ 234 class BridgeMasterPort : public MasterPort 235 { 236 237 private: 238 239 /** The bridge to which this port belongs. */ 240 Bridge& bridge; 241 242 /** 243 * The slave port on the other side of the bridge. 244 */ 245 BridgeSlavePort& slavePort; 246 247 /** Minimum delay though this bridge. */ 248 const Cycles delay; 249 250 /** 251 * Request packet queue. Request packets are held in this 252 * queue for a specified delay to model the processing delay 253 * of the bridge. We use a deque as we need to iterate over 254 * the items for functional accesses. 255 */ 256 std::deque<DeferredPacket> transmitList; 257 258 /** Max queue size for request packets */ 259 const unsigned int reqQueueLimit; 260 261 /** 262 * Handle send event, scheduled when the packet at the head of 263 * the outbound queue is ready to transmit (for timing 264 * accesses only). 265 */ 266 void trySendTiming(); 267 268 /** Send event for the request queue. */ 269 EventWrapper<BridgeMasterPort, 270 &BridgeMasterPort::trySendTiming> sendEvent; 271 272 public: 273 274 /** 275 * Constructor for the BridgeMasterPort. 276 * 277 * @param _name the port name including the owner 278 * @param _bridge the structural owner 279 * @param _slavePort the slave port on the other side of the bridge 280 * @param _delay the delay in cycles from receiving to sending 281 * @param _req_limit the size of the request queue 282 */ 283 BridgeMasterPort(const std::string& _name, Bridge& _bridge, 284 BridgeSlavePort& _slavePort, Cycles _delay, 285 int _req_limit); 286 287 /** 288 * Is this side blocked from accepting new request packets. 289 * 290 * @return true if the occupied space has reached the set limit 291 */ 292 bool reqQueueFull() const; 293 294 /** 295 * Queue a request packet to be sent out later and also schedule 296 * a send if necessary. 297 * 298 * @param pkt a request to send out after a delay 299 * @param when tick when response packet should be sent 300 */ 301 void schedTimingReq(PacketPtr pkt, Tick when); 302 303 /** 304 * Check a functional request against the packets in our 305 * request queue. 306 * 307 * @param pkt packet to check against 308 * 309 * @return true if we find a match 310 */ 311 bool checkFunctional(PacketPtr pkt); 312 313 protected: 314 315 /** When receiving a timing request from the peer port, 316 pass it to the bridge. */ 317 bool recvTimingResp(PacketPtr pkt); 318 319 /** When receiving a retry request from the peer port, 320 pass it to the bridge. */ 321 void recvRetry(); 322 }; 323 324 /** Slave port of the bridge. */ 325 BridgeSlavePort slavePort; 326 327 /** Master port of the bridge. */ 328 BridgeMasterPort masterPort; 329 330 public: 331 332 virtual BaseMasterPort& getMasterPort(const std::string& if_name, 333 PortID idx = InvalidPortID); 334 virtual BaseSlavePort& getSlavePort(const std::string& if_name, 335 PortID idx = InvalidPortID); 336 337 virtual void init(); 338 339 typedef BridgeParams Params; 340 341 Bridge(Params *p); 342}; 343 344#endif //__MEM_BRIDGE_HH__ 345