summaryrefslogtreecommitdiff
path: root/src/mem/bridge.cc
blob: eebf91a859edd4573c5726d7c8400fad637cb58b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415

/*
 * Copyright (c) 2006 The Regents of The University of Michigan
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Authors: Ali Saidi
 *          Steve Reinhardt
 */

/**
 * @file
 * Definition of a simple bus bridge without buffering.
 */

#include <algorithm>

#include "base/trace.hh"
#include "mem/bridge.hh"
#include "sim/builder.hh"

Bridge::BridgePort::BridgePort(const std::string &_name,
                               Bridge *_bridge, BridgePort *_otherPort,
                               int _delay, int _nack_delay, int _req_limit,
                               int _resp_limit, bool fix_partial_write)
    : Port(_name), bridge(_bridge), otherPort(_otherPort),
      delay(_delay), nackDelay(_nack_delay), fixPartialWrite(fix_partial_write),
      outstandingResponses(0), queuedRequests(0), inRetry(false),
      reqQueueLimit(_req_limit), respQueueLimit(_resp_limit), sendEvent(this)
{
}

Bridge::Bridge(Params *p)
    : MemObject(p->name),
      portA(p->name + "-portA", this, &portB, p->delay, p->nack_delay,
              p->req_size_a, p->resp_size_a, p->fix_partial_write_a),
      portB(p->name + "-portB", this, &portA, p->delay, p->nack_delay,
              p->req_size_b, p->resp_size_b, p->fix_partial_write_b),
      ackWrites(p->write_ack), _params(p)
{
    if (ackWrites)
        panic("No support for acknowledging writes\n");
}

Port *
Bridge::getPort(const std::string &if_name, int idx)
{
    BridgePort *port;

    if (if_name == "side_a")
        port = &portA;
    else if (if_name == "side_b")
        port = &portB;
    else
        return NULL;

    if (port->getPeer() != NULL)
        panic("bridge side %s already connected to.", if_name);
    return port;
}


void
Bridge::init()
{
    // Make sure that both sides are connected to.
    if (portA.getPeer() == NULL || portB.getPeer() == NULL)
        fatal("Both ports of bus bridge are not connected to a bus.\n");

    if (portA.peerBlockSize() != portB.peerBlockSize())
        fatal("Busses don't have the same block size... Not supported.\n");
}

bool
Bridge::BridgePort::respQueueFull()
{
    assert(outstandingResponses >= 0 && outstandingResponses <= respQueueLimit);
    return outstandingResponses >= respQueueLimit;
}

bool
Bridge::BridgePort::reqQueueFull()
{
    assert(queuedRequests >= 0 && queuedRequests <= reqQueueLimit);
    return queuedRequests >= reqQueueLimit;
}

/** Function called by the port when the bus is receiving a Timing
 * transaction.*/
bool
Bridge::BridgePort::recvTiming(PacketPtr pkt)
{
    DPRINTF(BusBridge, "recvTiming: src %d dest %d addr 0x%x\n",
                pkt->getSrc(), pkt->getDest(), pkt->getAddr());

    DPRINTF(BusBridge, "Local queue size: %d outreq: %d outresp: %d\n",
                    sendQueue.size(), queuedRequests, outstandingResponses);
    DPRINTF(BusBridge, "Remove queue size: %d outreq: %d outresp: %d\n",
                    otherPort->sendQueue.size(), otherPort->queuedRequests,
                    otherPort->outstandingResponses);

    if (pkt->isRequest() && otherPort->reqQueueFull() && pkt->result !=
            Packet::Nacked) {
        DPRINTF(BusBridge, "Remote queue full, nacking\n");
        nackRequest(pkt);
        return true;
    }

    if (pkt->needsResponse() && pkt->result != Packet::Nacked)
        if (respQueueFull()) {
            DPRINTF(BusBridge, "Local queue full, no space for response, nacking\n");
            DPRINTF(BusBridge, "queue size: %d outreq: %d outstanding resp: %d\n",
                    sendQueue.size(), queuedRequests, outstandingResponses);
            nackRequest(pkt);
            return true;
        } else {
            DPRINTF(BusBridge, "Request Needs response, reserving space\n");
            ++outstandingResponses;
        }

    otherPort->queueForSendTiming(pkt);

    return true;
}

void
Bridge::BridgePort::nackRequest(PacketPtr pkt)
{
    // Nack the packet
    pkt->result = Packet::Nacked;
    pkt->setDest(pkt->getSrc());

    //put it on the list to send
    Tick readyTime = curTick + nackDelay;
    PacketBuffer *buf = new PacketBuffer(pkt, readyTime, true);

    // nothing on the list, add it and we're done
    if (sendQueue.empty()) {
        assert(!sendEvent.scheduled());
        sendEvent.schedule(readyTime);
        sendQueue.push_back(buf);
        return;
    }

    assert(sendEvent.scheduled() || inRetry);

    // does it go at the end?
    if (readyTime >= sendQueue.back()->ready) {
        sendQueue.push_back(buf);
        return;
    }

    // ok, somewhere in the middle, fun
    std::list<PacketBuffer*>::iterator i = sendQueue.begin();
    std::list<PacketBuffer*>::iterator end = sendQueue.end();
    std::list<PacketBuffer*>::iterator begin = sendQueue.begin();
    bool done = false;

    while (i != end && !done) {
        if (readyTime < (*i)->ready) {
            if (i == begin)
                sendEvent.reschedule(readyTime);
            sendQueue.insert(i,buf);
            done = true;
        }
        i++;
    }
    assert(done);
}


void
Bridge::BridgePort::queueForSendTiming(PacketPtr pkt)
{
    if (pkt->isResponse() || pkt->result == Packet::Nacked) {
        // This is a response for a request we forwarded earlier.  The
        // corresponding PacketBuffer should be stored in the packet's
        // senderState field.
        PacketBuffer *buf = dynamic_cast<PacketBuffer*>(pkt->senderState);
        assert(buf != NULL);
        // set up new packet dest & senderState based on values saved
        // from original request
        buf->fixResponse(pkt);

        // Check if this packet was expecting a response and it's a nacked
        // packet, in which case we will never being seeing it
        if (buf->expectResponse && pkt->result == Packet::Nacked)
            --outstandingResponses;


        DPRINTF(BusBridge, "restoring  sender state: %#X, from packet buffer: %#X\n",
                        pkt->senderState, buf);
        DPRINTF(BusBridge, "  is response, new dest %d\n", pkt->getDest());
        delete buf;
    }


    if (pkt->isRequest() && pkt->result != Packet::Nacked) {
        ++queuedRequests;
    }



    Tick readyTime = curTick + delay;
    PacketBuffer *buf = new PacketBuffer(pkt, readyTime);
    DPRINTF(BusBridge, "old sender state: %#X, new sender state: %#X\n",
            buf->origSenderState, buf);

    // If we're about to put this packet at the head of the queue, we
    // need to schedule an event to do the transmit.  Otherwise there
    // should already be an event scheduled for sending the head
    // packet.
    if (sendQueue.empty()) {
        sendEvent.schedule(readyTime);
    }
    sendQueue.push_back(buf);
}

void
Bridge::BridgePort::trySend()
{
    assert(!sendQueue.empty());

    PacketBuffer *buf = sendQueue.front();

    assert(buf->ready <= curTick);

    PacketPtr pkt = buf->pkt;

    // Ugly! @todo When multilevel coherence works this will be removed
    if (pkt->cmd == MemCmd::WriteInvalidateReq && fixPartialWrite &&
            pkt->result != Packet::Nacked) {
        PacketPtr funcPkt = new Packet(pkt->req, MemCmd::WriteReq,
                            Packet::Broadcast);
        funcPkt->dataStatic(pkt->getPtr<uint8_t>());
        sendFunctional(funcPkt);
        pkt->cmd = MemCmd::WriteReq;
        delete funcPkt;
    }

    DPRINTF(BusBridge, "trySend: origSrc %d dest %d addr 0x%x\n",
            buf->origSrc, pkt->getDest(), pkt->getAddr());

    bool wasReq = pkt->isRequest();
    bool wasNacked = pkt->result == Packet::Nacked;

    if (sendTiming(pkt)) {
        // send successful
        sendQueue.pop_front();
        buf->pkt = NULL; // we no longer own packet, so it's not safe to look at it

        if (buf->expectResponse) {
            // Must wait for response
            DPRINTF(BusBridge, "  successful: awaiting response (%d)\n",
                    outstandingResponses);
        } else {
            // no response expected... deallocate packet buffer now.
            DPRINTF(BusBridge, "  successful: no response expected\n");
            delete buf;
        }

        if (!wasNacked) {
            if (wasReq)
                --queuedRequests;
            else
                --outstandingResponses;
        }

        // If there are more packets to send, schedule event to try again.
        if (!sendQueue.empty()) {
            buf = sendQueue.front();
            DPRINTF(BusBridge, "Scheduling next send\n");
            sendEvent.schedule(std::max(buf->ready, curTick + 1));
        }
    } else {
        DPRINTF(BusBridge, "  unsuccessful\n");
        inRetry = true;
    }
    DPRINTF(BusBridge, "trySend: queue size: %d outreq: %d outstanding resp: %d\n",
                    sendQueue.size(), queuedRequests, outstandingResponses);
}


void
Bridge::BridgePort::recvRetry()
{
    inRetry = false;
    Tick nextReady = sendQueue.front()->ready;
    if (nextReady <= curTick)
        trySend();
    else
        sendEvent.schedule(nextReady);
}

/** Function called by the port when the bus is receiving a Atomic
 * transaction.*/
Tick
Bridge::BridgePort::recvAtomic(PacketPtr pkt)
{
    // fix partial atomic writes... similar to the timing code that does the
    // same... will be removed once our code gets this right
    if (pkt->cmd == MemCmd::WriteInvalidateReq && fixPartialWrite) {

        PacketPtr funcPkt = new Packet(pkt->req, MemCmd::WriteReq,
                         Packet::Broadcast);
        funcPkt->dataStatic(pkt->getPtr<uint8_t>());
        otherPort->sendFunctional(funcPkt);
        delete funcPkt;
        pkt->cmd = MemCmd::WriteReq;
    }
    return delay + otherPort->sendAtomic(pkt);
}

/** Function called by the port when the bus is receiving a Functional
 * transaction.*/
void
Bridge::BridgePort::recvFunctional(PacketPtr pkt)
{
    std::list<PacketBuffer*>::iterator i;
    bool pktContinue = true;

    for (i = sendQueue.begin();  i != sendQueue.end(); ++i) {
        if (pkt->intersect((*i)->pkt)) {
            pktContinue &= fixPacket(pkt, (*i)->pkt);
        }
    }

    if (pktContinue) {
        otherPort->sendFunctional(pkt);
    }
}

/** Function called by the port when the bus is receiving a status change.*/
void
Bridge::BridgePort::recvStatusChange(Port::Status status)
{
    otherPort->sendStatusChange(status);
}

void
Bridge::BridgePort::getDeviceAddressRanges(AddrRangeList &resp,
                                           bool &snoop)
{
    otherPort->getPeerAddressRanges(resp, snoop);
}

BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bridge)

   Param<int> req_size_a;
   Param<int> req_size_b;
   Param<int> resp_size_a;
   Param<int> resp_size_b;
   Param<Tick> delay;
   Param<Tick> nack_delay;
   Param<bool> write_ack;
   Param<bool> fix_partial_write_a;
   Param<bool> fix_partial_write_b;

END_DECLARE_SIM_OBJECT_PARAMS(Bridge)

BEGIN_INIT_SIM_OBJECT_PARAMS(Bridge)

    INIT_PARAM(req_size_a, "The size of the queue for requests coming into side a"),
    INIT_PARAM(req_size_b, "The size of the queue for requests coming into side b"),
    INIT_PARAM(resp_size_a, "The size of the queue for responses coming into side a"),
    INIT_PARAM(resp_size_b, "The size of the queue for responses coming into side b"),
    INIT_PARAM(delay, "The miminum delay to cross this bridge"),
    INIT_PARAM(nack_delay, "The minimum delay to nack a packet"),
    INIT_PARAM(write_ack, "Acknowledge any writes that are received."),
    INIT_PARAM(fix_partial_write_a, "Fixup any partial block writes that are received"),
    INIT_PARAM(fix_partial_write_b, "Fixup any partial block writes that are received")

END_INIT_SIM_OBJECT_PARAMS(Bridge)

CREATE_SIM_OBJECT(Bridge)
{
    Bridge::Params *p = new Bridge::Params;
    p->name = getInstanceName();
    p->req_size_a = req_size_a;
    p->req_size_b = req_size_b;
    p->resp_size_a = resp_size_a;
    p->resp_size_b = resp_size_b;
    p->delay = delay;
    p->nack_delay = nack_delay;
    p->write_ack = write_ack;
    p->fix_partial_write_a = fix_partial_write_a;
    p->fix_partial_write_b = fix_partial_write_b;
    return new Bridge(p);
}

REGISTER_SIM_OBJECT("Bridge", Bridge)