Bus: Split the bus into a non-coherent and coherent bus

This patch introduces a class hierarchy of buses, a non-coherent one,
and a coherent one, splitting the existing bus functionality. By doing
so it also enables further specialisation of the two types of buses.

A non-coherent bus connects a number of non-snooping masters and
slaves, and routes the request and response packets based on the
address. The request packets issued by the master connected to a
non-coherent bus could still snoop in caches attached to a coherent
bus, as is the case with the I/O bus and memory bus in most system
configurations. No snoops will, however, reach any master on the
non-coherent bus itself. The non-coherent bus can be used as a
template for modelling PCI, PCIe, and non-coherent AMBA and OCP buses,
and is typically used for the I/O buses.

A coherent bus connects a number of (potentially) snooping masters and
slaves, and routes the request and response packets based on the
address, and also forwards all requests to the snoopers and deals with
the snoop responses. The coherent bus can be used as a template for
modelling QPI, HyperTransport, ACE and coherent OCP buses, and is
typically used for the L1-to-L2 buses and as the main system
interconnect.

The configuration scripts are updated to use a NoncoherentBus for all
peripheral and I/O buses.

A bit of minor tidying up has also been done.

--HG--
rename : src/mem/bus.cc => src/mem/coherent_bus.cc
rename : src/mem/bus.hh => src/mem/coherent_bus.hh
rename : src/mem/bus.cc => src/mem/noncoherent_bus.cc
rename : src/mem/bus.hh => src/mem/noncoherent_bus.hh

1 files changed, 21 insertions, 226 deletions

diff --git a/src/mem/bus.hh b/src/mem/bus.hh
index c35b46cc2..4f0e44b1c 100644
--- a/src/mem/bus.hh
+++ b/src/mem/bus.hh
@@ -45,7 +45,7 @@
 
 /**
  * @file
- * Declaration of a bus object.
+ * Declaration of an abstract bus base class.
  */
 
 #ifndef __MEM_BUS_HH__
@@ -53,155 +53,26 @@
 
 #include <list>
 #include <set>
-#include <string>
 
 #include "base/range.hh"
 #include "base/range_map.hh"
 #include "base/types.hh"
 #include "mem/mem_object.hh"
-#include "mem/packet.hh"
-#include "mem/port.hh"
-#include "params/Bus.hh"
-#include "sim/eventq.hh"
+#include "params/BaseBus.hh"
 
-class Bus : public MemObject
+/**
+ * The base bus contains the common elements of the non-coherent and
+ * coherent bus. It is an abstract class that does not have any of the
+ * functionality relating to the actual reception and transmission of
+ * packets, as this is left for the subclasses.
+ *
+ * The BaseBus is responsible for the basic flow control (busy or
+ * not), the administration of retries, and the address decoding.
+ */
+class BaseBus : public MemObject
 {
 
-    /**
-     * Declaration of the bus slave port type, one will be
-     * instantiated for each of the master interfaces connecting to
-     * the bus.
-     */
-    class BusSlavePort : public SlavePort
-    {
-      private:
-        /** A pointer to the bus to which this port belongs. */
-        Bus *bus;
-
-      public:
-
-        /** Constructor for the BusSlavePort.*/
-        BusSlavePort(const std::string &_name, Bus *_bus, PortID _id)
-            : SlavePort(_name, _bus, _id), bus(_bus)
-        { }
-
-      protected:
-
-        /**
-         * When receiving a timing request, pass it to the bus.
-         */
-        virtual bool recvTimingReq(PacketPtr pkt)
-        { return bus->recvTimingReq(pkt, id); }
-
-        /**
-         * When receiving a timing snoop response, pass it to the bus.
-         */
-        virtual bool recvTimingSnoopResp(PacketPtr pkt)
-        { return bus->recvTimingSnoopResp(pkt, id); }
-
-        /**
-         * When receiving an atomic request, pass it to the bus.
-         */
-        virtual Tick recvAtomic(PacketPtr pkt)
-        { return bus->recvAtomic(pkt, id); }
-
-        /**
-         * When receiving a functional request, pass it to the bus.
-         */
-        virtual void recvFunctional(PacketPtr pkt)
-        { bus->recvFunctional(pkt, id); }
-
-        /**
-         * When receiving a retry, pass it to the bus.
-         */
-        virtual void recvRetry()
-        { panic("Bus slave ports always succeed and should never retry.\n"); }
-
-        // This should return all the 'owned' addresses that are
-        // downstream from this bus, yes?  That is, the union of all
-        // the 'owned' address ranges of all the other interfaces on
-        // this bus...
-        virtual AddrRangeList getAddrRanges()
-        { return bus->getAddrRanges(); }
-
-        // Ask the bus to ask everyone on the bus what their block size is and
-        // take the max of it. This might need to be changed a bit if we ever
-        // support multiple block sizes.
-        virtual unsigned deviceBlockSize() const
-        { return bus->findBlockSize(); }
-
-    };
-
-    /**
-     * Declaration of the bus master port type, one will be
-     * instantiated for each of the slave interfaces connecting to the
-     * bus.
-     */
-    class BusMasterPort : public MasterPort
-    {
-      private:
-        /** A pointer to the bus to which this port belongs. */
-        Bus *bus;
-
-      public:
-
-        /** Constructor for the BusMasterPort.*/
-        BusMasterPort(const std::string &_name, Bus *_bus, PortID _id)
-            : MasterPort(_name, _bus, _id), bus(_bus)
-        { }
-
-        /**
-         * Determine if this port should be considered a snooper. This
-         * is determined by the bus.
-         *
-         * @return a boolean that is true if this port is snooping
-         */
-        virtual bool isSnooping() const
-        { return bus->isSnooping(); }
-
-      protected:
-
-        /**
-         * When receiving a timing response, pass it to the bus.
-         */
-        virtual bool recvTimingResp(PacketPtr pkt)
-        { return bus->recvTimingResp(pkt, id); }
-
-        /**
-         * When receiving a timing snoop request, pass it to the bus.
-         */
-        virtual void recvTimingSnoopReq(PacketPtr pkt)
-        { return bus->recvTimingSnoopReq(pkt, id); }
-
-        /**
-         * When receiving an atomic snoop request, pass it to the bus.
-         */
-        virtual Tick recvAtomicSnoop(PacketPtr pkt)
-        { return bus->recvAtomicSnoop(pkt, id); }
-
-        /**
-         * When receiving a functional snoop request, pass it to the bus.
-         */
-        virtual void recvFunctionalSnoop(PacketPtr pkt)
-        { bus->recvFunctionalSnoop(pkt, id); }
-
-        /** When reciving a range change from the peer port (at id),
-            pass it to the bus. */
-        virtual void recvRangeChange()
-        { bus->recvRangeChange(id); }
-
-        /** When reciving a retry from the peer port (at id),
-            pass it to the bus. */
-        virtual void recvRetry()
-        { bus->recvRetry(); }
-
-        // Ask the bus to ask everyone on the bus what their block size is and
-        // take the max of it. This might need to be changed a bit if we ever
-        // support multiple block sizes.
-        virtual unsigned deviceBlockSize() const
-        { return bus->findBlockSize(); }
-
-    };
+  protected:
 
     /** the clock speed for the bus */
     int clock;
@@ -219,41 +90,6 @@ class Bus : public MemObject
 
     AddrRangeList defaultRange;
 
-    std::vector<SlavePort*> snoopPorts;
-
-    /**
-     * Store the outstanding requests so we can determine which ones
-     * we generated and which ones were merely forwarded. This is used
-     * in the coherent bus when coherency responses come back.
-     */
-    std::set<RequestPtr> outstandingReq;
-
-    /** Function called by the port when the bus is recieving a Timing
-      request packet.*/
-    bool recvTimingReq(PacketPtr pkt, PortID slave_port_id);
-
-    /** Function called by the port when the bus is recieving a Timing
-      response packet.*/
-    bool recvTimingResp(PacketPtr pkt, PortID master_port_id);
-
-    /** Function called by the port when the bus is recieving a timing
-        snoop request.*/
-    void recvTimingSnoopReq(PacketPtr pkt, PortID master_port_id);
-
-    /** Function called by the port when the bus is recieving a timing
-        snoop response.*/
-    bool recvTimingSnoopResp(PacketPtr pkt, PortID slave_port_id);
-
-    /**
-     * Forward a timing packet to our snoopers, potentially excluding
-     * one of the connected coherent masters to avoid sending a packet
-     * back to where it came from.
-     *
-     * @param pkt Packet to forward
-     * @param exclude_slave_port_id Id of slave port to exclude
-     */
-    void forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id);
-
     /**
      * Determine if the bus is to be considered occupied when being
      * presented with a packet from a specific port. If so, the port
@@ -274,45 +110,6 @@ class Bus : public MemObject
      */
     void succeededTiming(Tick busy_time);
 
-    /** Function called by the port when the bus is recieving a Atomic
-      transaction.*/
-    Tick recvAtomic(PacketPtr pkt, PortID slave_port_id);
-
-    /** Function called by the port when the bus is recieving an
-        atomic snoop transaction.*/
-    Tick recvAtomicSnoop(PacketPtr pkt, PortID master_port_id);
-
-    /**
-     * Forward an atomic packet to our snoopers, potentially excluding
-     * one of the connected coherent masters to avoid sending a packet
-     * back to where it came from.
-     *
-     * @param pkt Packet to forward
-     * @param exclude_slave_port_id Id of slave port to exclude
-     *
-     * @return a pair containing the snoop response and snoop latency
-     */
-    std::pair<MemCmd, Tick> forwardAtomic(PacketPtr pkt,
-                                          PortID exclude_slave_port_id);
-
-    /** Function called by the port when the bus is recieving a Functional
-        transaction.*/
-    void recvFunctional(PacketPtr pkt, PortID slave_port_id);
-
-    /** Function called by the port when the bus is recieving a functional
-        snoop transaction.*/
-    void recvFunctionalSnoop(PacketPtr pkt, PortID master_port_id);
-
-    /**
-     * Forward a functional packet to our snoopers, potentially
-     * excluding one of the connected coherent masters to avoid
-     * sending a packet back to where it came from.
-     *
-     * @param pkt Packet to forward
-     * @param exclude_slave_port_id Id of slave port to exclude
-     */
-    void forwardFunctional(PacketPtr pkt, PortID exclude_slave_port_id);
-
     /** Timing function called by port when it is once again able to process
      * requests. */
     void recvRetry();
@@ -392,13 +189,6 @@ class Bus : public MemObject
      */
     AddrRangeList getAddrRanges();
 
-    /**
-     * Determine if the bus port is snooping or not.
-     *
-     * @return a boolean indicating if this port is snooping or not
-     */
-    bool isSnooping() const;
-
     /** Calculate the timing parameters for the packet.  Updates the
      * firstWordTime and finishTime fields of the packet object.
      * Returns the tick at which the packet header is completed (which
@@ -430,7 +220,7 @@ class Bus : public MemObject
     unsigned findBlockSize();
 
     // event used to schedule a release of the bus
-    EventWrapper<Bus, &Bus::releaseBus> busIdleEvent;
+    EventWrapper<BaseBus, &BaseBus::releaseBus> busIdleEvent;
 
     bool inRetry;
     std::set<PortID> inRecvRangeChange;
@@ -439,8 +229,11 @@ class Bus : public MemObject
     std::vector<SlavePort*> slavePorts;
     std::vector<MasterPort*> masterPorts;
 
+    /** Convenience typedefs. */
     typedef std::vector<SlavePort*>::iterator SlavePortIter;
+    typedef std::vector<MasterPort*>::iterator MasterPortIter;
     typedef std::vector<SlavePort*>::const_iterator SlavePortConstIter;
+    typedef std::vector<MasterPort*>::const_iterator MasterPortConstIter;
 
     /** An array of pointers to ports that retry should be called on because the
      * original send failed for whatever reason.*/
@@ -478,18 +271,20 @@ class Bus : public MemObject
     unsigned cachedBlockSize;
     bool cachedBlockSizeValid;
 
+    BaseBus(const BaseBusParams *p);
+
+    virtual ~BaseBus();
+
   public:
 
     /** A function used to return the port associated with this bus object. */
     virtual MasterPort& getMasterPort(const std::string& if_name, int idx = -1);
     virtual SlavePort& getSlavePort(const std::string& if_name, int idx = -1);
 
-    virtual void init();
     virtual void startup();
 
     unsigned int drain(Event *de);
 
-    Bus(const BusParams *p);
 };
 
 #endif //__MEM_BUS_HH__