text: /*
   * Copyright (c) 2011-2015, 2018 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 crossbar object.
   */
  
  #include "mem/xbar.hh"
  
  #include "base/logging.hh"
  #include "base/trace.hh"
  #include "debug/AddrRanges.hh"
  #include "debug/Drain.hh"
  #include "debug/XBar.hh"
  
  BaseXBar::BaseXBar(const BaseXBarParams *p)
      : MemObject(p),
        frontendLatency(p->frontend_latency),
        forwardLatency(p->forward_latency),
        responseLatency(p->response_latency),
        width(p->width),
        gotAddrRanges(p->port_default_connection_count +
                            p->port_master_connection_count, false),
        gotAllAddrRanges(false), defaultPortID(InvalidPortID),
        useDefaultRange(p->use_default_range)
  {}
  
  BaseXBar::~BaseXBar()
  {
      for (auto m: masterPorts)
          delete m;
  
      for (auto s: slavePorts)
          delete s;
  }
  
  Port &
  BaseXBar::getPort(const std::string &if_name, PortID idx)
  {
      if (if_name == "master" && idx < masterPorts.size()) {
          // the master port index translates directly to the vector position
          return *masterPorts[idx];
      } else  if (if_name == "default") {
          return *masterPorts[defaultPortID];
      } else if (if_name == "slave" && idx < slavePorts.size()) {
          // the slave port index translates directly to the vector position
          return *slavePorts[idx];
      } else {
          return MemObject::getPort(if_name, idx);
      }
  }
  
  void
  BaseXBar::calcPacketTiming(PacketPtr pkt, Tick header_delay)
  {
      // the crossbar will be called at a time that is not necessarily
      // coinciding with its own clock, so start by determining how long
      // until the next clock edge (could be zero)
      Tick offset = clockEdge() - curTick();
  
      // the header delay depends on the path through the crossbar, and
      // we therefore rely on the caller to provide the actual
      // value
      pkt->headerDelay += offset + header_delay;
  
      // note that we add the header delay to the existing value, and
      // align it to the crossbar clock
  
      // do a quick sanity check to ensure the timings are not being
      // ignored, note that this specific value may cause problems for
      // slower interconnects
      panic_if(pkt->headerDelay > SimClock::Int::us,
               "Encountered header delay exceeding 1 us\n");
  
      if (pkt->hasData()) {
          // the payloadDelay takes into account the relative time to
          // deliver the payload of the packet, after the header delay,
          // we take the maximum since the payload delay could already
          // be longer than what this parcitular crossbar enforces.
          pkt->payloadDelay = std::max<Tick>(pkt->payloadDelay,
                                             divCeil(pkt->getSize(), width) *
                                             clockPeriod());
      }
  
      // the payload delay is not paying for the clock offset as that is
      // already done using the header delay, and the payload delay is
      // also used to determine how long the crossbar layer is busy and
      // thus regulates throughput
  }
  
  template <typename SrcType, typename DstType>
  BaseXBar::Layer<SrcType, DstType>::Layer(DstType& _port, BaseXBar& _xbar,
                                         const std::string& _name) :
      port(_port), xbar(_xbar), _name(_name), state(IDLE),
      waitingForPeer(NULL), releaseEvent([this]{ releaseLayer(); }, name())
  {
  }
  
  template <typename SrcType, typename DstType>
  void BaseXBar::Layer<SrcType, DstType>::occupyLayer(Tick until)
  {
      // ensure the state is busy at this point, as the layer should
      // transition from idle as soon as it has decided to forward the
      // packet to prevent any follow-on calls to sendTiming seeing an
      // unoccupied layer
      assert(state == BUSY);
  
      // until should never be 0 as express snoops never occupy the layer
      assert(until != 0);
      xbar.schedule(releaseEvent, until);
  
      // account for the occupied ticks
      occupancy += until - curTick();
  
      DPRINTF(BaseXBar, "The crossbar layer is now busy from tick %d to %d\n",
              curTick(), until);
  }
  
  template <typename SrcType, typename DstType>
  bool
  BaseXBar::Layer<SrcType, DstType>::tryTiming(SrcType* src_port)
  {
      // if we are in the retry state, we will not see anything but the
      // retrying port (or in the case of the snoop ports the snoop
      // response port that mirrors the actual slave port) as we leave
      // this state again in zero time if the peer does not immediately
      // call the layer when receiving the retry
  
      // first we see if the layer is busy, next we check if the
      // destination port is already engaged in a transaction waiting
      // for a retry from the peer
      if (state == BUSY || waitingForPeer != NULL) {
          // the port should not be waiting already
          assert(std::find(waitingForLayer.begin(), waitingForLayer.end(),
                           src_port) == waitingForLayer.end());
  
          // put the port at the end of the retry list waiting for the
          // layer to be freed up (and in the case of a busy peer, for
          // that transaction to go through, and then the layer to free
          // up)
          waitingForLayer.push_back(src_port);
          return false;
      }
  
      state = BUSY;
  
      return true;
  }
  
  template <typename SrcType, typename DstType>
  void
  BaseXBar::Layer<SrcType, DstType>::succeededTiming(Tick busy_time)
  {
      // we should have gone from idle or retry to busy in the tryTiming
      // test
      assert(state == BUSY);
  
      // occupy the layer accordingly
      occupyLayer(busy_time);
  }
  
  template <typename SrcType, typename DstType>
  void
  BaseXBar::Layer<SrcType, DstType>::failedTiming(SrcType* src_port,
                                                Tick busy_time)
  {
      // ensure no one got in between and tried to send something to
      // this port
      assert(waitingForPeer == NULL);
  
      // if the source port is the current retrying one or not, we have
      // failed in forwarding and should track that we are now waiting
      // for the peer to send a retry
      waitingForPeer = src_port;
  
      // we should have gone from idle or retry to busy in the tryTiming
      // test
      assert(state == BUSY);
  
      // occupy the bus accordingly
      occupyLayer(busy_time);
  }
  
  template <typename SrcType, typename DstType>
  void
  BaseXBar::Layer<SrcType, DstType>::releaseLayer()
  {
      // releasing the bus means we should now be idle
      assert(state == BUSY);
      assert(!releaseEvent.scheduled());
  
      // update the state
      state = IDLE;
  
      // bus layer is now idle, so if someone is waiting we can retry
      if (!waitingForLayer.empty()) {
          // there is no point in sending a retry if someone is still
          // waiting for the peer
          if (waitingForPeer == NULL)
              retryWaiting();
      } else if (waitingForPeer == NULL && drainState() == DrainState::Draining) {
          DPRINTF(Drain, "Crossbar done draining, signaling drain manager\n");
          //If we weren't able to drain before, do it now.
          signalDrainDone();
      }
  }
  
  template <typename SrcType, typename DstType>
  void
  BaseXBar::Layer<SrcType, DstType>::retryWaiting()
  {
      // this should never be called with no one waiting
      assert(!waitingForLayer.empty());
  
      // we always go to retrying from idle
      assert(state == IDLE);
  
      // update the state
      state = RETRY;
  
      // set the retrying port to the front of the retry list and pop it
      // off the list
      SrcType* retryingPort = waitingForLayer.front();
      waitingForLayer.pop_front();
  
      // tell the port to retry, which in some cases ends up calling the
      // layer again
      sendRetry(retryingPort);
  
      // If the layer is still in the retry state, sendTiming wasn't
      // called in zero time (e.g. the cache does this when a writeback
      // is squashed)
      if (state == RETRY) {
          // update the state to busy and reset the retrying port, we
          // have done our bit and sent the retry
          state = BUSY;
  
          // occupy the crossbar layer until the next clock edge
          occupyLayer(xbar.clockEdge());
      }
  }
  
  template <typename SrcType, typename DstType>
  void
  BaseXBar::Layer<SrcType, DstType>::recvRetry()
  {
      // we should never get a retry without having failed to forward
      // something to this port
      assert(waitingForPeer != NULL);
  
      // add the port where the failed packet originated to the front of
      // the waiting ports for the layer, this allows us to call retry
      // on the port immediately if the crossbar layer is idle
      waitingForLayer.push_front(waitingForPeer);
  
      // we are no longer waiting for the peer
      waitingForPeer = NULL;
  
      // if the layer is idle, retry this port straight away, if we
      // are busy, then simply let the port wait for its turn
      if (state == IDLE) {
          retryWaiting();
      } else {
          assert(state == BUSY);
      }
  }
  
  PortID
  BaseXBar::findPort(AddrRange addr_range)
  {
      // we should never see any address lookups before we've got the
      // ranges of all connected slave modules
      assert(gotAllAddrRanges);
  
      // Check the address map interval tree
      auto i = portMap.contains(addr_range);
      if (i != portMap.end()) {
          return i->second;
      }
  
      // Check if this matches the default range
      if (useDefaultRange) {
          if (addr_range.isSubset(defaultRange)) {
              DPRINTF(AddrRanges, "  found addr %s on default\n",
                      addr_range.to_string());
              return defaultPortID;
          }
      } else if (defaultPortID != InvalidPortID) {
          DPRINTF(AddrRanges, "Unable to find destination for %s, "
                  "will use default port\n", addr_range.to_string());
          return defaultPortID;
      }
  
      // we should use the range for the default port and it did not
      // match, or the default port is not set
      fatal("Unable to find destination for %s on %s\n", addr_range.to_string(),
            name());
  }
  
  /** Function called by the port when the crossbar is receiving a range change.*/
  void
  BaseXBar::recvRangeChange(PortID master_port_id)
  {
      DPRINTF(AddrRanges, "Received range change from slave port %s\n",
              masterPorts[master_port_id]->getSlavePort().name());
  
      // remember that we got a range from this master port and thus the
      // connected slave module
      gotAddrRanges[master_port_id] = true;
  
      // update the global flag
      if (!gotAllAddrRanges) {
          // take a logical AND of all the ports and see if we got
          // ranges from everyone
          gotAllAddrRanges = true;
          std::vector<bool>::const_iterator r = gotAddrRanges.begin();
          while (gotAllAddrRanges &&  r != gotAddrRanges.end()) {
              gotAllAddrRanges &= *r++;
          }
          if (gotAllAddrRanges)
              DPRINTF(AddrRanges, "Got address ranges from all slaves\n");
      }
  
      // note that we could get the range from the default port at any
      // point in time, and we cannot assume that the default range is
      // set before the other ones are, so we do additional checks once
      // all ranges are provided
      if (master_port_id == defaultPortID) {
          // only update if we are indeed checking ranges for the
          // default port since the port might not have a valid range
          // otherwise
          if (useDefaultRange) {
              AddrRangeList ranges = masterPorts[master_port_id]->getAddrRanges();
  
              if (ranges.size() != 1)
                  fatal("Crossbar %s may only have a single default range",
                        name());
  
              defaultRange = ranges.front();
          }
      } else {
          // the ports are allowed to update their address ranges
          // dynamically, so remove any existing entries
          if (gotAddrRanges[master_port_id]) {
              for (auto p = portMap.begin(); p != portMap.end(); ) {
                  if (p->second == master_port_id)
                      // erasing invalidates the iterator, so advance it
                      // before the deletion takes place
                      portMap.erase(p++);
                  else
                      p++;
              }
          }
  
          AddrRangeList ranges = masterPorts[master_port_id]->getAddrRanges();
  
          for (const auto& r: ranges) {
              DPRINTF(AddrRanges, "Adding range %s for id %d\n",
                      r.to_string(), master_port_id);
              if (portMap.insert(r, master_port_id) == portMap.end()) {
                  PortID conflict_id = portMap.intersects(r)->second;
                  fatal("%s has two ports responding within range "
                        "%s:\n\t%s\n\t%s\n",
                        name(),
                        r.to_string(),
                        masterPorts[master_port_id]->getSlavePort().name(),
                        masterPorts[conflict_id]->getSlavePort().name());
              }
          }
      }
  
      // if we have received ranges from all our neighbouring slave
      // modules, go ahead and tell our connected master modules in
      // turn, this effectively assumes a tree structure of the system
      if (gotAllAddrRanges) {
          DPRINTF(AddrRanges, "Aggregating address ranges\n");
          xbarRanges.clear();
  
          // start out with the default range
          if (useDefaultRange) {
              if (!gotAddrRanges[defaultPortID])
                  fatal("Crossbar %s uses default range, but none provided",
                        name());
  
              xbarRanges.push_back(defaultRange);
              DPRINTF(AddrRanges, "-- Adding default %s\n",
                      defaultRange.to_string());
          }
  
          // merge all interleaved ranges and add any range that is not
          // a subset of the default range
          std::vector<AddrRange> intlv_ranges;
          for (const auto& r: portMap) {
              // if the range is interleaved then save it for now
              if (r.first.interleaved()) {
                  // if we already got interleaved ranges that are not
                  // part of the same range, then first do a merge
                  // before we add the new one
                  if (!intlv_ranges.empty() &&
                      !intlv_ranges.back().mergesWith(r.first)) {
                      DPRINTF(AddrRanges, "-- Merging range from %d ranges\n",
                              intlv_ranges.size());
                      AddrRange merged_range(intlv_ranges);
                      // next decide if we keep the merged range or not
                      if (!(useDefaultRange &&
                            merged_range.isSubset(defaultRange))) {
                          xbarRanges.push_back(merged_range);
                          DPRINTF(AddrRanges, "-- Adding merged range %s\n",
                                  merged_range.to_string());
                      }
                      intlv_ranges.clear();
                  }
                  intlv_ranges.push_back(r.first);
              } else {
                  // keep the current range if not a subset of the default
                  if (!(useDefaultRange &&
                        r.first.isSubset(defaultRange))) {
                      xbarRanges.push_back(r.first);
                      DPRINTF(AddrRanges, "-- Adding range %s\n",
                              r.first.to_string());
                  }
              }
          }
  
          // if there is still interleaved ranges waiting to be merged,
          // go ahead and do it
          if (!intlv_ranges.empty()) {
              DPRINTF(AddrRanges, "-- Merging range from %d ranges\n",
                      intlv_ranges.size());
              AddrRange merged_range(intlv_ranges);
              if (!(useDefaultRange && merged_range.isSubset(defaultRange))) {
                  xbarRanges.push_back(merged_range);
                  DPRINTF(AddrRanges, "-- Adding merged range %s\n",
                          merged_range.to_string());
              }
          }
  
          // also check that no range partially intersects with the
          // default range, this has to be done after all ranges are set
          // as there are no guarantees for when the default range is
          // update with respect to the other ones
          if (useDefaultRange) {
              for (const auto& r: xbarRanges) {
                  // see if the new range is partially
                  // overlapping the default range
                  if (r.intersects(defaultRange) &&
                      !r.isSubset(defaultRange))
                      fatal("Range %s intersects the "                    \
                            "default range of %s but is not a "           \
                            "subset\n", r.to_string(), name());
              }
          }
  
          // tell all our neighbouring master ports that our address
          // ranges have changed
          for (const auto& s: slavePorts)
              s->sendRangeChange();
      }
  }
  
  AddrRangeList
  BaseXBar::getAddrRanges() const
  {
      // we should never be asked without first having sent a range
      // change, and the latter is only done once we have all the ranges
      // of the connected devices
      assert(gotAllAddrRanges);
  
      // at the moment, this never happens, as there are no cycles in
      // the range queries and no devices on the master side of a crossbar
      // (CPU, cache, bridge etc) actually care about the ranges of the
      // ports they are connected to
  
      DPRINTF(AddrRanges, "Received address range request\n");
  
      return xbarRanges;
  }
  
  void
  BaseXBar::regStats()
  {
      ClockedObject::regStats();
  
      using namespace Stats;
  
      transDist
          .init(MemCmd::NUM_MEM_CMDS)
          .name(name() + ".trans_dist")
          .desc("Transaction distribution")
          .flags(nozero);
  
      // get the string representation of the commands
      for (int i = 0; i < MemCmd::NUM_MEM_CMDS; i++) {
          MemCmd cmd(i);
          const std::string &cstr = cmd.toString();
          transDist.subname(i, cstr);
      }
  
      pktCount
          .init(slavePorts.size(), masterPorts.size())
          .name(name() + ".pkt_count")
          .desc("Packet count per connected master and slave (bytes)")
          .flags(total | nozero | nonan);
  
      pktSize
          .init(slavePorts.size(), masterPorts.size())
          .name(name() + ".pkt_size")
          .desc("Cumulative packet size per connected master and slave (bytes)")
          .flags(total | nozero | nonan);
  
      // both the packet count and total size are two-dimensional
      // vectors, indexed by slave port id and master port id, thus the
      // neighbouring master and slave, they do not differentiate what
      // came from the master and was forwarded to the slave (requests
      // and snoop responses) and what came from the slave and was
      // forwarded to the master (responses and snoop requests)
      for (int i = 0; i < slavePorts.size(); i++) {
          pktCount.subname(i, slavePorts[i]->getMasterPort().name());
          pktSize.subname(i, slavePorts[i]->getMasterPort().name());
          for (int j = 0; j < masterPorts.size(); j++) {
              pktCount.ysubname(j, masterPorts[j]->getSlavePort().name());
              pktSize.ysubname(j, masterPorts[j]->getSlavePort().name());
          }
      }
  }
  
  template <typename SrcType, typename DstType>
  DrainState
  BaseXBar::Layer<SrcType, DstType>::drain()
  {
      //We should check that we're not "doing" anything, and that noone is
      //waiting. We might be idle but have someone waiting if the device we
      //contacted for a retry didn't actually retry.
      if (state != IDLE) {
          DPRINTF(Drain, "Crossbar not drained\n");
          return DrainState::Draining;
      } else {
          return DrainState::Drained;
      }
  }
  
  template <typename SrcType, typename DstType>
  void
  BaseXBar::Layer<SrcType, DstType>::regStats()
  {
      using namespace Stats;
  
      occupancy
          .name(name() + ".occupancy")
          .desc("Layer occupancy (ticks)")
          .flags(nozero);
  
      utilization
          .name(name() + ".utilization")
          .desc("Layer utilization (%)")
          .precision(1)
          .flags(nozero);
  
      utilization = 100 * occupancy / simTicks;
  }
  
  /**
   * Crossbar layer template instantiations. Could be removed with _impl.hh
   * file, but since there are only two given options (MasterPort and
   * SlavePort) it seems a bit excessive at this point.
   */
  template class BaseXBar::Layer<SlavePort, MasterPort>;
  template class BaseXBar::Layer<MasterPort, SlavePort>;
  