tport.cc revision 3342 
1/*
2 * Copyright (c) 2006 The Regents of The University of Michigan
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are
7 * met: redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer;
9 * redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution;
12 * neither the name of the copyright holders nor the names of its
13 * contributors may be used to endorse or promote products derived from
14 * this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * Authors: Ali Saidi
29 */
30
31#include "mem/tport.hh"
32
33void
34SimpleTimingPort::recvFunctional(Packet *pkt)
35{
36    std::list<Packet *>::iterator i;
37    std::list<Packet *>::iterator end;
38
39     //First check queued events
40    i = transmitList.begin();
41    end = transmitList.end();
42    while (i != end) {
43        Packet * target = *i;
44        // If the target contains data, and it overlaps the
45        // probed request, need to update data
46        if (target->intersect(pkt))
47            fixPacket(pkt, target);
48
49    }
50
51    //Then just do an atomic access and throw away the returned latency
52    if (pkt->result != Packet::Success)
53        recvAtomic(pkt);
54}
55
56bool
57SimpleTimingPort::recvTiming(Packet *pkt)
58{
59    // If the device is only a slave, it should only be sending
60    // responses, which should never get nacked.  There used to be
61    // code to hanldle nacks here, but I'm pretty sure it didn't work
62    // correctly with the drain code, so that would need to be fixed
63    // if we ever added it back.
64    assert(pkt->result != Packet::Nacked);
65    Tick latency = recvAtomic(pkt);
66    // turn packet around to go back to requester if response expected
67    if (pkt->needsResponse()) {
68        pkt->makeTimingResponse();
69        sendTimingLater(pkt, latency);
70    }
71    else {
72        if (pkt->cmd != Packet::UpgradeReq)
73        {
74            delete pkt->req;
75            delete pkt;
76        }
77    }
78    return true;
79}
80
81void
82SimpleTimingPort::recvRetry()
83{
84    assert(outTiming > 0);
85    assert(!transmitList.empty());
86    if (sendTiming(transmitList.front())) {
87        transmitList.pop_front();
88        outTiming--;
89        DPRINTF(Bus, "No Longer waiting on retry\n");
90        if (!transmitList.empty())
91            sendTimingLater(transmitList.front(), 1);
92    }
93
94    if (transmitList.empty() && drainEvent) {
95        drainEvent->process();
96        drainEvent = NULL;
97    }
98}
99
100void
101SimpleTimingPort::SendEvent::process()
102{
103    assert(port->outTiming > 0);
104    if (!port->transmitList.empty() && port->transmitList.front() != packet) {
105        //We are not the head of the list
106        port->transmitList.push_back(packet);
107    } else if (port->sendTiming(packet)) {
108        // send successful
109        if (port->transmitList.size()) {
110            port->transmitList.pop_front();
111            port->outTiming--;
112           if (!port->transmitList.empty())
113                port->sendTimingLater(port->transmitList.front(), 1);
114        }
115        if (port->transmitList.empty() && port->drainEvent) {
116            port->drainEvent->process();
117            port->drainEvent = NULL;
118        }
119    } else {
120        // send unsuccessful (due to flow control).  Will get retry
121        // callback later; save for then if not already
122        DPRINTF(Bus, "Waiting on retry\n");
123        if (!(port->transmitList.front() == packet))
124            port->transmitList.push_back(packet);
125    }
126}
127
128
129unsigned int
130SimpleTimingPort::drain(Event *de)
131{
132    if (outTiming == 0 && transmitList.size() == 0)
133        return 0;
134    drainEvent = de;
135    return 1;
136}
137