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

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42#include "sim/builder.hh"
43
44Bridge::BridgePort::BridgePort(const std::string &_name,
45 Bridge *_bridge, BridgePort *_otherPort,
46 int _delay, int _queueLimit,
47 bool fix_partial_write)
48 : Port(_name), bridge(_bridge), otherPort(_otherPort),
49 delay(_delay), fixPartialWrite(fix_partial_write),
50 outstandingResponses(0), queueLimit(_queueLimit), sendEvent(this)
51{
52}
53
54Bridge::Bridge(const std::string &n, int qsa, int qsb,
55 Tick _delay, int write_ack, bool fix_partial_write_a,
56 bool fix_partial_write_b)
57 : MemObject(n),
58 portA(n + "-portA", this, &portB, _delay, qsa, fix_partial_write_a),

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87 // Make sure that both sides are connected to.
88 if (portA.getPeer() == NULL || portB.getPeer() == NULL)
89 fatal("Both ports of bus bridge are not connected to a bus.\n");
90
91 if (portA.peerBlockSize() != portB.peerBlockSize())
92 fatal("Busses don't have the same block size... Not supported.\n");
93}
94
95
96/** Function called by the port when the bus is receiving a Timing
97 * transaction.*/
98bool
99Bridge::BridgePort::recvTiming(PacketPtr pkt)
100{
101 if (pkt->flags & SNOOP_COMMIT) {
102 DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n",
103 pkt->getSrc(), pkt->getDest(), pkt->getAddr());
104
105 return otherPort->queueForSendTiming(pkt);
106 }
107 else {
108 // Else it's just a snoop, properly return if we are blocking
109 return !queueFull();
110 }
111}
112
113
114bool
115Bridge::BridgePort::queueForSendTiming(PacketPtr pkt)
116{
117 if (queueFull()) {
118 DPRINTF(BusBridge, "Queue full, returning false\n");
119 return false;
120 }
121
122 if (pkt->isResponse()) {
123 // This is a response for a request we forwarded earlier. The
124 // corresponding PacketBuffer should be stored in the packet's
125 // senderState field.
126 PacketBuffer *buf = dynamic_cast<PacketBuffer*>(pkt->senderState);
127 assert(buf != NULL);
128 // set up new packet dest & senderState based on values saved
129 // from original request
130 buf->fixResponse(pkt);
131 DPRINTF(BusBridge, "restoring sender state: %#X, from packet buffer: %#X\n",
132 pkt->senderState, buf);
133 DPRINTF(BusBridge, " is response, new dest %d\n", pkt->getDest());
134 delete buf;
135 }
136
137 Tick readyTime = curTick + delay;
138 PacketBuffer *buf = new PacketBuffer(pkt, readyTime);
139 DPRINTF(BusBridge, "old sender state: %#X, new sender state: %#X\n",
140 buf->origSenderState, buf);
141
142 // If we're about to put this packet at the head of the queue, we
143 // need to schedule an event to do the transmit. Otherwise there
144 // should already be an event scheduled for sending the head
145 // packet.
146 if (sendQueue.empty()) {
147 sendEvent.schedule(readyTime);
148 }
149
150 sendQueue.push_back(buf);
151
152 return true;
153}
154
155void
156Bridge::BridgePort::trySend()
157{
158 assert(!sendQueue.empty());
159
160 bool was_full = queueFull();
161 int pbs = peerBlockSize();
162
163 PacketBuffer *buf = sendQueue.front();
164
165 assert(buf->ready <= curTick);
166
167 PacketPtr pkt = buf->pkt;
168
169 pkt->flags &= ~SNOOP_COMMIT; //CLear it if it was set
170
171 if (pkt->cmd == MemCmd::WriteInvalidateReq && fixPartialWrite &&
172 pkt->getOffset(pbs) && pkt->getSize() != pbs) {
173 buf->partialWriteFix(this);
174 pkt = buf->pkt;
175 }
176
177 DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n",
178 buf->origSrc, pkt->getDest(), pkt->getAddr());
179
180
181 if (sendTiming(pkt)) {
182 // send successful
183 sendQueue.pop_front();
184 buf->pkt = NULL; // we no longer own packet, so it's not safe to look at it
185
186 if (buf->expectResponse) {
187 // Must wait for response. We just need to count outstanding
188 // responses (in case we want to cap them); PacketBuffer
189 // pointer will be recovered on response.
190 ++outstandingResponses;
191 DPRINTF(BusBridge, " successful: awaiting response (%d)\n",
192 outstandingResponses);
193 } else {
194 // no response expected... deallocate packet buffer now.
195 DPRINTF(BusBridge, " successful: no response expected\n");
196 delete buf;
197 }
198
199 // If there are more packets to send, schedule event to try again.
200 if (!sendQueue.empty()) {
201 buf = sendQueue.front();
202 sendEvent.schedule(std::max(buf->ready, curTick + 1));
203 }
204 // Let things start sending again
205 if (was_full) {
206 DPRINTF(BusBridge, "Queue was full, sending retry\n");
207 otherPort->sendRetry();
208 }
209
210 } else {
211 DPRINTF(BusBridge, " unsuccessful\n");
212 buf->undoPartialWriteFix();
213 }
214}
215
216
217void
218Bridge::BridgePort::recvRetry()
219{
220 trySend();
221}

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285
286CREATE_SIM_OBJECT(Bridge)
287{
288 return new Bridge(getInstanceName(), queue_size_a, queue_size_b, delay,
289 write_ack, fix_partial_write_a, fix_partial_write_b);
290}
291
292REGISTER_SIM_OBJECT("Bridge", Bridge)