tport.cc revision 3349 
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(PacketPtr pkt)
35{
36    //First check queued events
37    std::list<PacketPtr>::iterator i = transmitList.begin();
38    std::list<PacketPtr>::iterator end = transmitList.end();
39    bool cont = true;
40
41    while (i != end && cont) {
42        PacketPtr target = *i;
43        // If the target contains data, and it overlaps the
44        // probed request, need to update data
45        if (target->intersect(pkt))
46            fixPacket(pkt, target);
47
48    }
49    //Then just do an atomic access and throw away the returned latency
50    if (cont)
51        recvAtomic(pkt);
52}
53
54bool
55SimpleTimingPort::recvTiming(PacketPtr pkt)
56{
57    // If the device is only a slave, it should only be sending
58    // responses, which should never get nacked.  There used to be
59    // code to hanldle nacks here, but I'm pretty sure it didn't work
60    // correctly with the drain code, so that would need to be fixed
61    // if we ever added it back.
62    assert(pkt->result != Packet::Nacked);
63    Tick latency = recvAtomic(pkt);
64    // turn packet around to go back to requester if response expected
65    if (pkt->needsResponse()) {
66        pkt->makeTimingResponse();
67        sendTimingLater(pkt, latency);
68    }
69    else {
70        if (pkt->cmd != Packet::UpgradeReq)
71        {
72            delete pkt->req;
73            delete pkt;
74        }
75    }
76    return true;
77}
78
79void
80SimpleTimingPort::recvRetry()
81{
82    assert(outTiming > 0);
83    assert(!transmitList.empty());
84    if (sendTiming(transmitList.front())) {
85        transmitList.pop_front();
86        outTiming--;
87        DPRINTF(Bus, "No Longer waiting on retry\n");
88        if (!transmitList.empty())
89            sendTimingLater(transmitList.front(), 1);
90    }
91
92    if (transmitList.empty() && drainEvent) {
93        drainEvent->process();
94        drainEvent = NULL;
95    }
96}
97
98void
99SimpleTimingPort::SendEvent::process()
100{
101    assert(port->outTiming > 0);
102    if (!port->transmitList.empty() && port->transmitList.front() != packet) {
103        //We are not the head of the list
104        port->transmitList.push_back(packet);
105    } else if (port->sendTiming(packet)) {
106        // send successful
107        if (port->transmitList.size()) {
108            port->transmitList.pop_front();
109            port->outTiming--;
110           if (!port->transmitList.empty())
111                port->sendTimingLater(port->transmitList.front(), 1);
112        }
113        if (port->transmitList.empty() && port->drainEvent) {
114            port->drainEvent->process();
115            port->drainEvent = NULL;
116        }
117    } else {
118        // send unsuccessful (due to flow control).  Will get retry
119        // callback later; save for then if not already
120        DPRINTF(Bus, "Waiting on retry\n");
121        if (!(port->transmitList.front() == packet))
122            port->transmitList.push_back(packet);
123    }
124}
125
126
127unsigned int
128SimpleTimingPort::drain(Event *de)
129{
130    if (outTiming == 0 && transmitList.size() == 0)
131        return 0;
132    drainEvent = de;
133    return 1;
134}
135