bridge.cc revision 3662 
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 _queueLimit)
47    : Port(_name), bridge(_bridge), otherPort(_otherPort),
48      delay(_delay), outstandingResponses(0),
49      queueLimit(_queueLimit), sendEvent(this)
50{
51}
52
53Bridge::Bridge(const std::string &n, int qsa, int qsb,
54               Tick _delay, int write_ack)
55    : MemObject(n),
56      portA(n + "-portA", this, &portB, _delay, qsa),
57      portB(n + "-portB", this, &portA, _delay, qsa),
58      ackWrites(write_ack)
59{
60}
61
62Port *
63Bridge::getPort(const std::string &if_name, int idx)
64{
65    BridgePort *port;
66
67    if (if_name == "side_a")
68        port = &portA;
69    else if (if_name == "side_b")
70        port = &portB;
71    else
72        return NULL;
73
74    if (port->getPeer() != NULL)
75        panic("bridge side %s already connected to.", if_name);
76    return port;
77}
78
79
80void
81Bridge::init()
82{
83    // Make sure that both sides are connected to.
84    if (portA.getPeer() == NULL || portB.getPeer() == NULL)
85        panic("Both ports of bus bridge are not connected to a bus.\n");
86}
87
88
89/** Function called by the port when the bus is receiving a Timing
90 * transaction.*/
91bool
92Bridge::BridgePort::recvTiming(PacketPtr pkt)
93{
94    if (pkt->flags & SNOOP_COMMIT) {
95        DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n",
96                pkt->getSrc(), pkt->getDest(), pkt->getAddr());
97
98        return otherPort->queueForSendTiming(pkt);
99    }
100    else {
101        // Else it's just a snoop, properly return if we are blocking
102        return !queueFull();
103    }
104}
105
106
107bool
108Bridge::BridgePort::queueForSendTiming(PacketPtr pkt)
109{
110    if (queueFull())
111        return false;
112
113   if (pkt->isResponse()) {
114        // This is a response for a request we forwarded earlier.  The
115        // corresponding PacketBuffer should be stored in the packet's
116        // senderState field.
117        PacketBuffer *buf = dynamic_cast<PacketBuffer*>(pkt->senderState);
118        assert(buf != NULL);
119        // set up new packet dest & senderState based on values saved
120        // from original request
121        buf->fixResponse(pkt);
122        DPRINTF(BusBridge, "restoring  sender state: %#X, from packet buffer: %#X\n",
123                        pkt->senderState, buf);
124        DPRINTF(BusBridge, "  is response, new dest %d\n", pkt->getDest());
125        delete buf;
126    }
127
128    Tick readyTime = curTick + delay;
129    PacketBuffer *buf = new PacketBuffer(pkt, readyTime);
130    DPRINTF(BusBridge, "old sender state: %#X, new sender state: %#X\n",
131            buf->origSenderState, buf);
132
133    // If we're about to put this packet at the head of the queue, we
134    // need to schedule an event to do the transmit.  Otherwise there
135    // should already be an event scheduled for sending the head
136    // packet.
137    if (sendQueue.empty()) {
138        sendEvent.schedule(readyTime);
139    }
140
141    sendQueue.push_back(buf);
142
143    return true;
144}
145
146void
147Bridge::BridgePort::trySend()
148{
149    assert(!sendQueue.empty());
150
151    bool was_full = queueFull();
152
153    PacketBuffer *buf = sendQueue.front();
154
155    assert(buf->ready <= curTick);
156
157    PacketPtr pkt = buf->pkt;
158
159    DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n",
160            buf->origSrc, pkt->getDest(), pkt->getAddr());
161
162    pkt->flags &= ~SNOOP_COMMIT; //CLear it if it was set
163    if (sendTiming(pkt)) {
164        // send successful
165        sendQueue.pop_front();
166        buf->pkt = NULL; // we no longer own packet, so it's not safe to look at it
167
168        if (buf->expectResponse) {
169            // Must wait for response.  We just need to count outstanding
170            // responses (in case we want to cap them); PacketBuffer
171            // pointer will be recovered on response.
172            ++outstandingResponses;
173            DPRINTF(BusBridge, "  successful: awaiting response (%d)\n",
174                    outstandingResponses);
175        } else {
176            // no response expected... deallocate packet buffer now.
177            DPRINTF(BusBridge, "  successful: no response expected\n");
178            delete buf;
179        }
180
181        // If there are more packets to send, schedule event to try again.
182        if (!sendQueue.empty()) {
183            buf = sendQueue.front();
184            sendEvent.schedule(std::max(buf->ready, curTick + 1));
185        }
186        // Let things start sending again
187        if (was_full) {
188          DPRINTF(BusBridge, "Queue was full, sending retry\n");
189          otherPort->sendRetry();
190        }
191
192    } else {
193        DPRINTF(BusBridge, "  unsuccessful\n");
194    }
195}
196
197
198void
199Bridge::BridgePort::recvRetry()
200{
201    trySend();
202}
203
204/** Function called by the port when the bus is receiving a Atomic
205 * transaction.*/
206Tick
207Bridge::BridgePort::recvAtomic(PacketPtr pkt)
208{
209    return otherPort->sendAtomic(pkt) + delay;
210}
211
212/** Function called by the port when the bus is receiving a Functional
213 * transaction.*/
214void
215Bridge::BridgePort::recvFunctional(PacketPtr pkt)
216{
217    std::list<PacketBuffer*>::iterator i;
218    bool pktContinue = true;
219
220    for (i = sendQueue.begin();  i != sendQueue.end(); ++i) {
221        if (pkt->intersect((*i)->pkt)) {
222            pktContinue &= fixPacket(pkt, (*i)->pkt);
223        }
224    }
225
226    if (pktContinue) {
227        otherPort->sendFunctional(pkt);
228    }
229}
230
231/** Function called by the port when the bus is receiving a status change.*/
232void
233Bridge::BridgePort::recvStatusChange(Port::Status status)
234{
235    otherPort->sendStatusChange(status);
236}
237
238void
239Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList &resp,
240                                           AddrRangeList &snoop)
241{
242    otherPort->getPeerAddressRanges(resp, snoop);
243}
244
245BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bridge)
246
247   Param<int> queue_size_a;
248   Param<int> queue_size_b;
249   Param<Tick> delay;
250   Param<bool> write_ack;
251
252END_DECLARE_SIM_OBJECT_PARAMS(Bridge)
253
254BEGIN_INIT_SIM_OBJECT_PARAMS(Bridge)
255
256    INIT_PARAM(queue_size_a, "The size of the queue for data coming into side a"),
257    INIT_PARAM(queue_size_b, "The size of the queue for data coming into side b"),
258    INIT_PARAM(delay, "The miminum delay to cross this bridge"),
259    INIT_PARAM(write_ack, "Acknowledge any writes that are received.")
260
261END_INIT_SIM_OBJECT_PARAMS(Bridge)
262
263CREATE_SIM_OBJECT(Bridge)
264{
265    return new Bridge(getInstanceName(), queue_size_a, queue_size_b, delay,
266            write_ack);
267}
268
269REGISTER_SIM_OBJECT("Bridge", Bridge)
270