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/*
* 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
*/
/**
* @file
* Definition of a bus object.
*/
#include "base/misc.hh"
#include "base/trace.hh"
#include "mem/bus.hh"
#include "sim/builder.hh"
Port *
Bus::getPort(const std::string &if_name, int idx)
{
if (if_name == "default")
if (defaultPort == NULL) {
defaultPort = new BusPort(csprintf("%s-default",name()), this,
defaultId);
return defaultPort;
} else
fatal("Default port already set\n");
// if_name ignored? forced to be empty?
int id = interfaces.size();
BusPort *bp = new BusPort(csprintf("%s-p%d", name(), id), this, id);
interfaces.push_back(bp);
return bp;
}
/** Get the ranges of anyone other buses that we are connected to. */
void
Bus::init()
{
std::vector<Port*>::iterator intIter;
for (intIter = interfaces.begin(); intIter != interfaces.end(); intIter++)
(*intIter)->sendStatusChange(Port::RangeChange);
}
Bus::BusFreeEvent::BusFreeEvent(Bus *_bus) : Event(&mainEventQueue), bus(_bus)
{}
void Bus::BusFreeEvent::process()
{
bus->recvRetry(0);
}
const char * Bus::BusFreeEvent::description()
{
return "bus became available";
}
void
Bus::occupyBus(int numCycles)
{
//Move up when the bus will next be free
//We avoid the use of divide by adding repeatedly
//This should be faster if the value is updated frequently, but should
//be may be slower otherwise.
//Bring tickNextIdle up to the present tick
//There is some potential ambiguity where a cycle starts, which might make
//a difference when devices are acting right around a cycle boundary. Using
//a < allows things which happen exactly on a cycle boundary to take up only
//the following cycle. Anthing that happens later will have to "wait" for the
//end of that cycle, and then start using the bus after that.
while (tickNextIdle < curTick)
tickNextIdle += clock;
//Advance it numCycles bus cycles.
//XXX Should this use the repeating add trick as well?
tickNextIdle += (numCycles * clock);
if (!busIdle.scheduled()) {
busIdle.schedule(tickNextIdle);
} else {
busIdle.reschedule(tickNextIdle);
}
}
/** Function called by the port when the bus is receiving a Timing
* transaction.*/
bool
Bus::recvTiming(Packet *pkt)
{
Port *port;
DPRINTF(Bus, "recvTiming: packet src %d dest %d addr 0x%x cmd %s\n",
pkt->getSrc(), pkt->getDest(), pkt->getAddr(), pkt->cmdString());
Port *pktPort = interfaces[pkt->getSrc()];
// If the bus is busy, or other devices are in line ahead of the current one,
// put this device on the retry list.
if (tickNextIdle > curTick || (retryList.size() && pktPort != retryingPort)) {
addToRetryList(pktPort);
return false;
}
// If the bus is blocked, make the device wait.
if (!(port = findDestPort(pkt, pkt->getSrc()))) {
addToRetryList(pktPort);
return false;
}
// The packet will be sent. Figure out how long it occupies the bus.
int numCycles = 0;
// Requests need one cycle to send an address
if (pkt->isRequest())
numCycles++;
else if (pkt->isResponse() || pkt->hasData()) {
// If a packet has data, it needs ceil(size/width) cycles to send it
// We're using the "adding instead of dividing" trick again here
if (pkt->hasData()) {
int dataSize = pkt->getSize();
for (int transmitted = 0; transmitted < dataSize;
transmitted += width) {
numCycles++;
}
} else {
// If the packet didn't have data, it must have been a response.
// Those use the bus for one cycle to send their data.
numCycles++;
}
}
occupyBus(numCycles);
if (port->sendTiming(pkt)) {
// Packet was successfully sent. Return true.
return true;
}
// Packet not successfully sent. Leave or put it on the retry list.
addToRetryList(pktPort);
return false;
}
void
Bus::recvRetry(int id)
{
//If there's anything waiting...
if (retryList.size()) {
retryingPort = retryList.front();
retryingPort->sendRetry();
//If the retryingPort pointer isn't null, either sendTiming wasn't
//called, or it was and the packet was successfully sent.
if (retryingPort) {
retryList.pop_front();
retryingPort = 0;
}
}
}
Port *
Bus::findDestPort(PacketPtr pkt, int id)
{
Port * port = NULL;
short dest = pkt->getDest();
if (dest == Packet::Broadcast) {
if (timingSnoopPhase1(pkt)) {
timingSnoopPhase2(pkt);
port = findPort(pkt->getAddr(), pkt->getSrc());
}
//else, port stays NULL
} else {
assert(dest >= 0 && dest < interfaces.size());
assert(dest != pkt->getSrc()); // catch infinite loops
port = interfaces[dest];
}
return port;
}
Port *
Bus::findPort(Addr addr, int id)
{
/* An interval tree would be a better way to do this. --ali. */
int dest_id = -1;
int i = 0;
bool found = false;
AddrRangeIter iter;
while (i < portList.size() && !found)
{
if (portList[i].range == addr) {
dest_id = portList[i].portId;
found = true;
DPRINTF(Bus, " found addr %#llx on device %d\n", addr, dest_id);
}
i++;
}
// Check if this matches the default range
if (dest_id == -1) {
for (iter = defaultRange.begin(); iter != defaultRange.end(); iter++) {
if (*iter == addr) {
DPRINTF(Bus, " found addr %#llx on default\n", addr);
return defaultPort;
}
}
panic("Unable to find destination for addr: %#llx", addr);
}
// we shouldn't be sending this back to where it came from
assert(dest_id != id);
return interfaces[dest_id];
}
std::vector<int>
Bus::findSnoopPorts(Addr addr, int id)
{
int i = 0;
AddrRangeIter iter;
std::vector<int> ports;
while (i < portSnoopList.size())
{
if (portSnoopList[i].range == addr && portSnoopList[i].portId != id) {
//Careful to not overlap ranges
//or snoop will be called more than once on the port
ports.push_back(portSnoopList[i].portId);
DPRINTF(Bus, " found snoop addr %#llx on device%d\n", addr,
portSnoopList[i].portId);
}
i++;
}
return ports;
}
void
Bus::atomicSnoop(Packet *pkt)
{
std::vector<int> ports = findSnoopPorts(pkt->getAddr(), pkt->getSrc());
while (!ports.empty())
{
interfaces[ports.back()]->sendAtomic(pkt);
ports.pop_back();
}
}
bool
Bus::timingSnoopPhase1(Packet *pkt)
{
std::vector<int> ports = findSnoopPorts(pkt->getAddr(), pkt->getSrc());
bool success = true;
while (!ports.empty() && success)
{
snoopCallbacks.push_back(ports.back());
success = interfaces[ports.back()]->sendTiming(pkt);
ports.pop_back();
}
if (!success)
{
while (!snoopCallbacks.empty())
{
interfaces[snoopCallbacks.back()]->sendStatusChange(Port::SnoopSquash);
snoopCallbacks.pop_back();
}
return false;
}
return true;
}
void
Bus::timingSnoopPhase2(Packet *pkt)
{
bool success;
pkt->flags |= SNOOP_COMMIT;
while (!snoopCallbacks.empty())
{
success = interfaces[snoopCallbacks.back()]->sendTiming(pkt);
//We should not fail on snoop callbacks
assert(success);
snoopCallbacks.pop_back();
}
}
/** Function called by the port when the bus is receiving a Atomic
* transaction.*/
Tick
Bus::recvAtomic(Packet *pkt)
{
DPRINTF(Bus, "recvAtomic: packet src %d dest %d addr 0x%x cmd %s\n",
pkt->getSrc(), pkt->getDest(), pkt->getAddr(), pkt->cmdString());
assert(pkt->getDest() == Packet::Broadcast);
atomicSnoop(pkt);
return findPort(pkt->getAddr(), pkt->getSrc())->sendAtomic(pkt);
}
/** Function called by the port when the bus is receiving a Functional
* transaction.*/
void
Bus::recvFunctional(Packet *pkt)
{
DPRINTF(Bus, "recvFunctional: packet src %d dest %d addr 0x%x cmd %s\n",
pkt->getSrc(), pkt->getDest(), pkt->getAddr(), pkt->cmdString());
assert(pkt->getDest() == Packet::Broadcast);
atomicSnoop(pkt);
findPort(pkt->getAddr(), pkt->getSrc())->sendFunctional(pkt);
}
/** Function called by the port when the bus is receiving a status change.*/
void
Bus::recvStatusChange(Port::Status status, int id)
{
AddrRangeList ranges;
AddrRangeList snoops;
int x;
AddrRangeIter iter;
assert(status == Port::RangeChange &&
"The other statuses need to be implemented.");
DPRINTF(BusAddrRanges, "received RangeChange from device id %d\n", id);
if (id == defaultId) {
defaultRange.clear();
defaultPort->getPeerAddressRanges(ranges, snoops);
assert(snoops.size() == 0);
for(iter = ranges.begin(); iter != ranges.end(); iter++) {
defaultRange.push_back(*iter);
DPRINTF(BusAddrRanges, "Adding range %#llx - %#llx for default range\n",
iter->start, iter->end);
}
} else {
assert((id < interfaces.size() && id >= 0) || id == -1);
Port *port = interfaces[id];
std::vector<DevMap>::iterator portIter;
std::vector<DevMap>::iterator snoopIter;
// Clean out any previously existent ids
for (portIter = portList.begin(); portIter != portList.end(); ) {
if (portIter->portId == id)
portIter = portList.erase(portIter);
else
portIter++;
}
for (snoopIter = portSnoopList.begin(); snoopIter != portSnoopList.end(); ) {
if (snoopIter->portId == id)
snoopIter = portSnoopList.erase(snoopIter);
else
snoopIter++;
}
port->getPeerAddressRanges(ranges, snoops);
for(iter = snoops.begin(); iter != snoops.end(); iter++) {
DevMap dm;
dm.portId = id;
dm.range = *iter;
DPRINTF(BusAddrRanges, "Adding snoop range %#llx - %#llx for id %d\n",
dm.range.start, dm.range.end, id);
portSnoopList.push_back(dm);
}
for(iter = ranges.begin(); iter != ranges.end(); iter++) {
DevMap dm;
dm.portId = id;
dm.range = *iter;
DPRINTF(BusAddrRanges, "Adding range %#llx - %#llx for id %d\n",
dm.range.start, dm.range.end, id);
portList.push_back(dm);
}
}
DPRINTF(MMU, "port list has %d entries\n", portList.size());
// tell all our peers that our address range has changed.
// Don't tell the device that caused this change, it already knows
for (x = 0; x < interfaces.size(); x++)
if (x != id)
interfaces[x]->sendStatusChange(Port::RangeChange);
if (id != defaultId && defaultPort)
defaultPort->sendStatusChange(Port::RangeChange);
}
void
Bus::addressRanges(AddrRangeList &resp, AddrRangeList &snoop, int id)
{
std::vector<DevMap>::iterator portIter;
AddrRangeIter dflt_iter;
bool subset;
resp.clear();
snoop.clear();
DPRINTF(BusAddrRanges, "received address range request, returning:\n");
for (dflt_iter = defaultRange.begin(); dflt_iter != defaultRange.end();
dflt_iter++) {
resp.push_back(*dflt_iter);
DPRINTF(BusAddrRanges, " -- %#llx : %#llx\n",dflt_iter->start,
dflt_iter->end);
}
for (portIter = portList.begin(); portIter != portList.end(); portIter++) {
subset = false;
for (dflt_iter = defaultRange.begin(); dflt_iter != defaultRange.end();
dflt_iter++) {
if ((portIter->range.start < dflt_iter->start &&
portIter->range.end >= dflt_iter->start) ||
(portIter->range.start < dflt_iter->end &&
portIter->range.end >= dflt_iter->end))
fatal("Devices can not set ranges that itersect the default set\
but are not a subset of the default set.\n");
if (portIter->range.start >= dflt_iter->start &&
portIter->range.end <= dflt_iter->end) {
subset = true;
DPRINTF(BusAddrRanges, " -- %#llx : %#llx is a SUBSET\n",
portIter->range.start, portIter->range.end);
}
}
if (portIter->portId != id && !subset) {
resp.push_back(portIter->range);
DPRINTF(BusAddrRanges, " -- %#llx : %#llx\n",
portIter->range.start, portIter->range.end);
}
}
}
BEGIN_DECLARE_SIM_OBJECT_PARAMS(Bus)
Param<int> bus_id;
Param<int> clock;
Param<int> width;
END_DECLARE_SIM_OBJECT_PARAMS(Bus)
BEGIN_INIT_SIM_OBJECT_PARAMS(Bus)
INIT_PARAM(bus_id, "a globally unique bus id"),
INIT_PARAM(clock, "bus clock speed"),
INIT_PARAM(width, "width of the bus (bits)")
END_INIT_SIM_OBJECT_PARAMS(Bus)
CREATE_SIM_OBJECT(Bus)
{
return new Bus(getInstanceName(), bus_id, clock, width);
}
REGISTER_SIM_OBJECT("Bus", Bus)
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