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Diffstat (limited to 'src/mem/coherent_bus.cc')
| -rw-r--r-- | src/mem/coherent_bus.cc | 493 |
1 files changed, 493 insertions, 0 deletions
diff --git a/src/mem/coherent_bus.cc b/src/mem/coherent_bus.cc new file mode 100644 index 000000000..b40e84762 --- /dev/null +++ b/src/mem/coherent_bus.cc @@ -0,0 +1,493 @@ +/* + * Copyright (c) 2011-2012 ARM Limited + * All rights reserved + * + * The license below extends only to copyright in the software and shall + * not be construed as granting a license to any other intellectual + * property including but not limited to intellectual property relating + * to a hardware implementation of the functionality of the software + * licensed hereunder. You may use the software subject to the license + * terms below provided that you ensure that this notice is replicated + * unmodified and in its entirety in all distributions of the software, + * modified or unmodified, in source code or in binary form. + * + * 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 + * Andreas Hansson + * William Wang + */ + +/** + * @file + * Definition of a bus object. + */ + +#include "base/misc.hh" +#include "base/trace.hh" +#include "debug/BusAddrRanges.hh" +#include "debug/CoherentBus.hh" +#include "mem/coherent_bus.hh" + +CoherentBus::CoherentBus(const CoherentBusParams *p) + : BaseBus(p) +{ + // create the ports based on the size of the master and slave + // vector ports, and the presence of the default port, the ports + // are enumerated starting from zero + for (int i = 0; i < p->port_master_connection_count; ++i) { + std::string portName = csprintf("%s-p%d", name(), i); + MasterPort* bp = new CoherentBusMasterPort(portName, *this, i); + masterPorts.push_back(bp); + } + + // see if we have a default slave device connected and if so add + // our corresponding master port + if (p->port_default_connection_count) { + defaultPortID = masterPorts.size(); + std::string portName = csprintf("%s-default", name()); + MasterPort* bp = new CoherentBusMasterPort(portName, *this, + defaultPortID); + masterPorts.push_back(bp); + } + + // create the slave ports, once again starting at zero + for (int i = 0; i < p->port_slave_connection_count; ++i) { + std::string portName = csprintf("%s-p%d", name(), i); + SlavePort* bp = new CoherentBusSlavePort(portName, *this, i); + slavePorts.push_back(bp); + } + + clearPortCache(); +} + +void +CoherentBus::init() +{ + // iterate over our slave ports and determine which of our + // neighbouring master ports are snooping and add them as snoopers + for (SlavePortConstIter p = slavePorts.begin(); p != slavePorts.end(); + ++p) { + if ((*p)->getMasterPort().isSnooping()) { + DPRINTF(BusAddrRanges, "Adding snooping master %s\n", + (*p)->getMasterPort().name()); + snoopPorts.push_back(*p); + } + } + + if (snoopPorts.empty()) + warn("CoherentBus %s has no snooping ports attached!\n", name()); +} + +bool +CoherentBus::recvTimingReq(PacketPtr pkt, PortID slave_port_id) +{ + // determine the source port based on the id + SlavePort *src_port = slavePorts[slave_port_id]; + + // test if the bus should be considered occupied for the current + // port, and exclude express snoops from the check + if (!pkt->isExpressSnoop() && isOccupied(src_port)) { + DPRINTF(CoherentBus, "recvTimingReq: src %s %s 0x%x BUSY\n", + src_port->name(), pkt->cmdString(), pkt->getAddr()); + return false; + } + + DPRINTF(CoherentBus, "recvTimingReq: src %s %s 0x%x\n", + src_port->name(), pkt->cmdString(), pkt->getAddr()); + + // set the source port for routing of the response + pkt->setSrc(slave_port_id); + + Tick headerFinishTime = pkt->isExpressSnoop() ? 0 : calcPacketTiming(pkt); + Tick packetFinishTime = pkt->isExpressSnoop() ? 0 : pkt->finishTime; + + // uncacheable requests need never be snooped + if (!pkt->req->isUncacheable()) { + // the packet is a memory-mapped request and should be + // broadcasted to our snoopers but the source + forwardTiming(pkt, slave_port_id); + } + + // remember if we add an outstanding req so we can undo it if + // necessary, if the packet needs a response, we should add it + // as outstanding and express snoops never fail so there is + // not need to worry about them + bool add_outstanding = !pkt->isExpressSnoop() && pkt->needsResponse(); + + // keep track that we have an outstanding request packet + // matching this request, this is used by the coherency + // mechanism in determining what to do with snoop responses + // (in recvTimingSnoop) + if (add_outstanding) { + // we should never have an exsiting request outstanding + assert(outstandingReq.find(pkt->req) == outstandingReq.end()); + outstandingReq.insert(pkt->req); + } + + // since it is a normal request, determine the destination + // based on the address and attempt to send the packet + bool success = masterPorts[findPort(pkt->getAddr())]->sendTimingReq(pkt); + + if (!success) { + // inhibited packets should never be forced to retry + assert(!pkt->memInhibitAsserted()); + + // if it was added as outstanding and the send failed, then + // erase it again + if (add_outstanding) + outstandingReq.erase(pkt->req); + + DPRINTF(CoherentBus, "recvTimingReq: src %s %s 0x%x RETRY\n", + src_port->name(), pkt->cmdString(), pkt->getAddr()); + + addToRetryList(src_port); + occupyBus(headerFinishTime); + + return false; + } + + succeededTiming(packetFinishTime); + + return true; +} + +bool +CoherentBus::recvTimingResp(PacketPtr pkt, PortID master_port_id) +{ + // determine the source port based on the id + MasterPort *src_port = masterPorts[master_port_id]; + + // test if the bus should be considered occupied for the current + // port + if (isOccupied(src_port)) { + DPRINTF(CoherentBus, "recvTimingResp: src %s %s 0x%x BUSY\n", + src_port->name(), pkt->cmdString(), pkt->getAddr()); + return false; + } + + DPRINTF(CoherentBus, "recvTimingResp: src %s %s 0x%x\n", + src_port->name(), pkt->cmdString(), pkt->getAddr()); + + calcPacketTiming(pkt); + Tick packetFinishTime = pkt->finishTime; + + // the packet is a normal response to a request that we should + // have seen passing through the bus + assert(outstandingReq.find(pkt->req) != outstandingReq.end()); + + // remove it as outstanding + outstandingReq.erase(pkt->req); + + // send the packet to the destination through one of our slave + // ports, as determined by the destination field + bool success M5_VAR_USED = slavePorts[pkt->getDest()]->sendTimingResp(pkt); + + // currently it is illegal to block responses... can lead to + // deadlock + assert(success); + + succeededTiming(packetFinishTime); + + return true; +} + +void +CoherentBus::recvTimingSnoopReq(PacketPtr pkt, PortID master_port_id) +{ + DPRINTF(CoherentBus, "recvTimingSnoopReq: src %s %s 0x%x\n", + masterPorts[master_port_id]->name(), pkt->cmdString(), + pkt->getAddr()); + + // we should only see express snoops from caches + assert(pkt->isExpressSnoop()); + + // set the source port for routing of the response + pkt->setSrc(master_port_id); + + // forward to all snoopers + forwardTiming(pkt, InvalidPortID); + + // a snoop request came from a connected slave device (one of + // our master ports), and if it is not coming from the slave + // device responsible for the address range something is + // wrong, hence there is nothing further to do as the packet + // would be going back to where it came from + assert(master_port_id == findPort(pkt->getAddr())); + + // this is an express snoop and is never forced to retry + assert(!inRetry); +} + +bool +CoherentBus::recvTimingSnoopResp(PacketPtr pkt, PortID slave_port_id) +{ + // determine the source port based on the id + SlavePort* src_port = slavePorts[slave_port_id]; + + // test if the bus should be considered occupied for the current + // port + if (isOccupied(src_port)) { + DPRINTF(CoherentBus, "recvTimingSnoopResp: src %s %s 0x%x BUSY\n", + src_port->name(), pkt->cmdString(), pkt->getAddr()); + return false; + } + + DPRINTF(CoherentBus, "recvTimingSnoop: src %s %s 0x%x\n", + src_port->name(), pkt->cmdString(), pkt->getAddr()); + + // get the destination from the packet + PortID dest = pkt->getDest(); + + // responses are never express snoops + assert(!pkt->isExpressSnoop()); + + calcPacketTiming(pkt); + Tick packetFinishTime = pkt->finishTime; + + // determine if the response is from a snoop request we + // created as the result of a normal request (in which case it + // should be in the outstandingReq), or if we merely forwarded + // someone else's snoop request + if (outstandingReq.find(pkt->req) == outstandingReq.end()) { + // this is a snoop response to a snoop request we + // forwarded, e.g. coming from the L1 and going to the L2 + // this should be forwarded as a snoop response + bool success M5_VAR_USED = masterPorts[dest]->sendTimingSnoopResp(pkt); + assert(success); + } else { + // we got a snoop response on one of our slave ports, + // i.e. from a coherent master connected to the bus, and + // since we created the snoop request as part of + // recvTiming, this should now be a normal response again + outstandingReq.erase(pkt->req); + + // this is a snoop response from a coherent master, with a + // destination field set on its way through the bus as + // request, hence it should never go back to where the + // snoop response came from, but instead to where the + // original request came from + assert(slave_port_id != dest); + + // as a normal response, it should go back to a master + // through one of our slave ports + bool success M5_VAR_USED = slavePorts[dest]->sendTimingResp(pkt); + + // currently it is illegal to block responses... can lead + // to deadlock + assert(success); + } + + succeededTiming(packetFinishTime); + + return true; +} + + +void +CoherentBus::forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id) +{ + for (SlavePortIter s = snoopPorts.begin(); s != snoopPorts.end(); ++s) { + SlavePort *p = *s; + // we could have gotten this request from a snooping master + // (corresponding to our own slave port that is also in + // snoopPorts) and should not send it back to where it came + // from + if (exclude_slave_port_id == InvalidPortID || + p->getId() != exclude_slave_port_id) { + // cache is not allowed to refuse snoop + p->sendTimingSnoopReq(pkt); + } + } +} + +Tick +CoherentBus::recvAtomic(PacketPtr pkt, PortID slave_port_id) +{ + DPRINTF(CoherentBus, "recvAtomic: packet src %s addr 0x%x cmd %s\n", + slavePorts[slave_port_id]->name(), pkt->getAddr(), + pkt->cmdString()); + + MemCmd snoop_response_cmd = MemCmd::InvalidCmd; + Tick snoop_response_latency = 0; + + // uncacheable requests need never be snooped + if (!pkt->req->isUncacheable()) { + // forward to all snoopers but the source + std::pair<MemCmd, Tick> snoop_result = + forwardAtomic(pkt, slave_port_id); + snoop_response_cmd = snoop_result.first; + snoop_response_latency = snoop_result.second; + } + + // even if we had a snoop response, we must continue and also + // perform the actual request at the destination + PortID dest_id = findPort(pkt->getAddr()); + + // forward the request to the appropriate destination + Tick response_latency = masterPorts[dest_id]->sendAtomic(pkt); + + // if we got a response from a snooper, restore it here + if (snoop_response_cmd != MemCmd::InvalidCmd) { + // no one else should have responded + assert(!pkt->isResponse()); + pkt->cmd = snoop_response_cmd; + response_latency = snoop_response_latency; + } + + pkt->finishTime = curTick() + response_latency; + return response_latency; +} + +Tick +CoherentBus::recvAtomicSnoop(PacketPtr pkt, PortID master_port_id) +{ + DPRINTF(CoherentBus, "recvAtomicSnoop: packet src %s addr 0x%x cmd %s\n", + masterPorts[master_port_id]->name(), pkt->getAddr(), + pkt->cmdString()); + + // forward to all snoopers + std::pair<MemCmd, Tick> snoop_result = + forwardAtomic(pkt, InvalidPortID); + MemCmd snoop_response_cmd = snoop_result.first; + Tick snoop_response_latency = snoop_result.second; + + if (snoop_response_cmd != MemCmd::InvalidCmd) + pkt->cmd = snoop_response_cmd; + + pkt->finishTime = curTick() + snoop_response_latency; + return snoop_response_latency; +} + +std::pair<MemCmd, Tick> +CoherentBus::forwardAtomic(PacketPtr pkt, PortID exclude_slave_port_id) +{ + // the packet may be changed on snoops, record the original + // command to enable us to restore it between snoops so that + // additional snoops can take place properly + MemCmd orig_cmd = pkt->cmd; + MemCmd snoop_response_cmd = MemCmd::InvalidCmd; + Tick snoop_response_latency = 0; + + for (SlavePortIter s = snoopPorts.begin(); s != snoopPorts.end(); ++s) { + SlavePort *p = *s; + // we could have gotten this request from a snooping master + // (corresponding to our own slave port that is also in + // snoopPorts) and should not send it back to where it came + // from + if (exclude_slave_port_id == InvalidPortID || + p->getId() != exclude_slave_port_id) { + Tick latency = p->sendAtomicSnoop(pkt); + // in contrast to a functional access, we have to keep on + // going as all snoopers must be updated even if we get a + // response + if (pkt->isResponse()) { + // response from snoop agent + assert(pkt->cmd != orig_cmd); + assert(pkt->memInhibitAsserted()); + // should only happen once + assert(snoop_response_cmd == MemCmd::InvalidCmd); + // save response state + snoop_response_cmd = pkt->cmd; + snoop_response_latency = latency; + // restore original packet state for remaining snoopers + pkt->cmd = orig_cmd; + } + } + } + + // the packet is restored as part of the loop and any potential + // snoop response is part of the returned pair + return std::make_pair(snoop_response_cmd, snoop_response_latency); +} + +void +CoherentBus::recvFunctional(PacketPtr pkt, PortID slave_port_id) +{ + if (!pkt->isPrint()) { + // don't do DPRINTFs on PrintReq as it clutters up the output + DPRINTF(CoherentBus, + "recvFunctional: packet src %s addr 0x%x cmd %s\n", + slavePorts[slave_port_id]->name(), pkt->getAddr(), + pkt->cmdString()); + } + + // uncacheable requests need never be snooped + if (!pkt->req->isUncacheable()) { + // forward to all snoopers but the source + forwardFunctional(pkt, slave_port_id); + } + + // there is no need to continue if the snooping has found what we + // were looking for and the packet is already a response + if (!pkt->isResponse()) { + PortID dest_id = findPort(pkt->getAddr()); + + masterPorts[dest_id]->sendFunctional(pkt); + } +} + +void +CoherentBus::recvFunctionalSnoop(PacketPtr pkt, PortID master_port_id) +{ + if (!pkt->isPrint()) { + // don't do DPRINTFs on PrintReq as it clutters up the output + DPRINTF(CoherentBus, + "recvFunctionalSnoop: packet src %s addr 0x%x cmd %s\n", + masterPorts[master_port_id]->name(), pkt->getAddr(), + pkt->cmdString()); + } + + // forward to all snoopers + forwardFunctional(pkt, InvalidPortID); +} + +void +CoherentBus::forwardFunctional(PacketPtr pkt, PortID exclude_slave_port_id) +{ + for (SlavePortIter s = snoopPorts.begin(); s != snoopPorts.end(); ++s) { + SlavePort *p = *s; + // we could have gotten this request from a snooping master + // (corresponding to our own slave port that is also in + // snoopPorts) and should not send it back to where it came + // from + if (exclude_slave_port_id == InvalidPortID || + p->getId() != exclude_slave_port_id) + p->sendFunctionalSnoop(pkt); + + // if we get a response we are done + if (pkt->isResponse()) { + break; + } + } +} + +CoherentBus * +CoherentBusParams::create() +{ + return new CoherentBus(this); +} |