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40 * Authors: Ron Dreslinski
48 * Declaration of a coherent bus.
51 #ifndef __MEM_COHERENT_BUS_HH__
52 #define __MEM_COHERENT_BUS_HH__
55 #include "params/CoherentBus.hh"
58 * A coherent bus connects a number of (potentially) snooping masters
59 * and slaves, and routes the request and response packets based on
60 * the address, and also forwards all requests to the snoopers and
61 * deals with the snoop responses.
63 * The coherent bus can be used as a template for modelling QPI,
64 * HyperTransport, ACE and coherent OCP buses, and is typically used
65 * for the L1-to-L2 buses and as the main system interconnect.
66 * @sa \ref gem5MemorySystem "gem5 Memory System"
68 class CoherentBus : public BaseBus
74 * Declare the three layers of this bus, one for requests, one
75 * for responses, and one for snoop responses
77 Layer<SlavePort> reqLayer;
78 Layer<MasterPort> respLayer;
79 Layer<SlavePort> snoopRespLayer;
82 * Declaration of the coherent bus slave port type, one will be
83 * instantiated for each of the master ports connecting to the
86 class CoherentBusSlavePort : public SlavePort
91 /** A reference to the bus to which this port belongs. */
96 CoherentBusSlavePort(const std::string &_name,
97 CoherentBus &_bus, PortID _id)
98 : SlavePort(_name, &_bus, _id), bus(_bus)
104 * When receiving a timing request, pass it to the bus.
106 virtual bool recvTimingReq(PacketPtr pkt)
107 { return bus.recvTimingReq(pkt, id); }
110 * When receiving a timing snoop response, pass it to the bus.
112 virtual bool recvTimingSnoopResp(PacketPtr pkt)
113 { return bus.recvTimingSnoopResp(pkt, id); }
116 * When receiving an atomic request, pass it to the bus.
118 virtual Tick recvAtomic(PacketPtr pkt)
119 { return bus.recvAtomic(pkt, id); }
122 * When receiving a functional request, pass it to the bus.
124 virtual void recvFunctional(PacketPtr pkt)
125 { bus.recvFunctional(pkt, id); }
128 * When receiving a retry, pass it to the bus.
130 virtual void recvRetry()
131 { panic("Bus slave ports always succeed and should never retry.\n"); }
134 * Return the union of all adress ranges seen by this bus.
136 virtual AddrRangeList getAddrRanges() const
137 { return bus.getAddrRanges(); }
140 * Get the maximum block size as seen by the bus.
142 virtual unsigned deviceBlockSize() const
143 { return bus.findBlockSize(); }
148 * Declaration of the coherent bus master port type, one will be
149 * instantiated for each of the slave interfaces connecting to the
152 class CoherentBusMasterPort : public MasterPort
155 /** A reference to the bus to which this port belongs. */
160 CoherentBusMasterPort(const std::string &_name,
161 CoherentBus &_bus, PortID _id)
162 : MasterPort(_name, &_bus, _id), bus(_bus)
168 * Determine if this port should be considered a snooper. For
169 * a coherent bus master port this is always true.
171 * @return a boolean that is true if this port is snooping
173 virtual bool isSnooping() const
177 * When receiving a timing response, pass it to the bus.
179 virtual bool recvTimingResp(PacketPtr pkt)
180 { return bus.recvTimingResp(pkt, id); }
183 * When receiving a timing snoop request, pass it to the bus.
185 virtual void recvTimingSnoopReq(PacketPtr pkt)
186 { return bus.recvTimingSnoopReq(pkt, id); }
189 * When receiving an atomic snoop request, pass it to the bus.
191 virtual Tick recvAtomicSnoop(PacketPtr pkt)
192 { return bus.recvAtomicSnoop(pkt, id); }
195 * When receiving a functional snoop request, pass it to the bus.
197 virtual void recvFunctionalSnoop(PacketPtr pkt)
198 { bus.recvFunctionalSnoop(pkt, id); }
200 /** When reciving a range change from the peer port (at id),
201 pass it to the bus. */
202 virtual void recvRangeChange()
203 { bus.recvRangeChange(id); }
205 /** When reciving a retry from the peer port (at id),
206 pass it to the bus. */
207 virtual void recvRetry()
210 // Ask the bus to ask everyone on the bus what their block size is and
211 // take the max of it. This might need to be changed a bit if we ever
212 // support multiple block sizes.
213 virtual unsigned deviceBlockSize() const
214 { return bus.findBlockSize(); }
218 std::vector<SlavePort*> snoopPorts;
221 * Store the outstanding requests so we can determine which ones
222 * we generated and which ones were merely forwarded. This is used
223 * in the coherent bus when coherency responses come back.
225 std::set<RequestPtr> outstandingReq;
227 /** Function called by the port when the bus is recieving a Timing
229 virtual bool recvTimingReq(PacketPtr pkt, PortID slave_port_id);
231 /** Function called by the port when the bus is recieving a Timing
233 virtual bool recvTimingResp(PacketPtr pkt, PortID master_port_id);
235 /** Function called by the port when the bus is recieving a timing
237 virtual void recvTimingSnoopReq(PacketPtr pkt, PortID master_port_id);
239 /** Function called by the port when the bus is recieving a timing
241 virtual bool recvTimingSnoopResp(PacketPtr pkt, PortID slave_port_id);
243 /** Timing function called by port when it is once again able to process
248 * Forward a timing packet to our snoopers, potentially excluding
249 * one of the connected coherent masters to avoid sending a packet
250 * back to where it came from.
252 * @param pkt Packet to forward
253 * @param exclude_slave_port_id Id of slave port to exclude
255 void forwardTiming(PacketPtr pkt, PortID exclude_slave_port_id);
257 /** Function called by the port when the bus is recieving a Atomic
259 Tick recvAtomic(PacketPtr pkt, PortID slave_port_id);
261 /** Function called by the port when the bus is recieving an
262 atomic snoop transaction.*/
263 Tick recvAtomicSnoop(PacketPtr pkt, PortID master_port_id);
266 * Forward an atomic packet to our snoopers, potentially excluding
267 * one of the connected coherent masters to avoid sending a packet
268 * back to where it came from.
270 * @param pkt Packet to forward
271 * @param exclude_slave_port_id Id of slave port to exclude
273 * @return a pair containing the snoop response and snoop latency
275 std::pair<MemCmd, Tick> forwardAtomic(PacketPtr pkt,
276 PortID exclude_slave_port_id);
278 /** Function called by the port when the bus is recieving a Functional
280 void recvFunctional(PacketPtr pkt, PortID slave_port_id);
282 /** Function called by the port when the bus is recieving a functional
284 void recvFunctionalSnoop(PacketPtr pkt, PortID master_port_id);
287 * Forward a functional packet to our snoopers, potentially
288 * excluding one of the connected coherent masters to avoid
289 * sending a packet back to where it came from.
291 * @param pkt Packet to forward
292 * @param exclude_slave_port_id Id of slave port to exclude
294 void forwardFunctional(PacketPtr pkt, PortID exclude_slave_port_id);
300 CoherentBus(const CoherentBusParams *p);
302 unsigned int drain(Event *de);
305 #endif //__MEM_COHERENT_BUS_HH__