src/dev/net/i8254xGBe.hh - amd/gem5 - Git at Google

 /*
  * 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
  * Device model for Intel's 8254x line of gigabit ethernet controllers.
  */

 #ifndef __DEV_NET_I8254XGBE_HH__
 #define __DEV_NET_I8254XGBE_HH__

 #include <deque>
 #include <string>

 #include "base/cp_annotate.hh"
 #include "base/inet.hh"
 #include "debug/EthernetDesc.hh"
 #include "debug/EthernetIntr.hh"
 #include "dev/net/etherdevice.hh"
 #include "dev/net/etherint.hh"
 #include "dev/net/etherpkt.hh"
 #include "dev/net/i8254xGBe_defs.hh"
 #include "dev/net/pktfifo.hh"
 #include "dev/pci/device.hh"
 #include "params/IGbE.hh"
 #include "sim/eventq.hh"

 class IGbEInt;

 class IGbE : public EtherDevice
 {
   private:
     IGbEInt *etherInt;
     CPA *cpa;

     // device registers
     iGbReg::Regs regs;

     // eeprom data, status and control bits
     int eeOpBits, eeAddrBits, eeDataBits;
     uint8_t eeOpcode, eeAddr;
     uint16_t flash[iGbReg::EEPROM_SIZE];

     // packet fifos
     PacketFifo rxFifo;
     PacketFifo txFifo;

     // Packet that we are currently putting into the txFifo
     EthPacketPtr txPacket;

     // Should to Rx/Tx State machine tick?
     bool inTick;
     bool rxTick;
     bool txTick;
     bool txFifoTick;

     bool rxDmaPacket;

     // Number of bytes copied from current RX packet
     unsigned pktOffset;

     // Delays in managaging descriptors
     Tick fetchDelay, wbDelay;
     Tick fetchCompDelay, wbCompDelay;
     Tick rxWriteDelay, txReadDelay;

     // Event and function to deal with RDTR timer expiring
     void rdtrProcess() {
         rxDescCache.writeback(0);
         DPRINTF(EthernetIntr,
                 "Posting RXT interrupt because RDTR timer expired\n");
         postInterrupt(iGbReg::IT_RXT);
     }

     EventFunctionWrapper rdtrEvent;

     // Event and function to deal with RADV timer expiring
     void radvProcess() {
         rxDescCache.writeback(0);
         DPRINTF(EthernetIntr,
                 "Posting RXT interrupt because RADV timer expired\n");
         postInterrupt(iGbReg::IT_RXT);
     }

     EventFunctionWrapper radvEvent;

     // Event and function to deal with TADV timer expiring
     void tadvProcess() {
         txDescCache.writeback(0);
         DPRINTF(EthernetIntr,
                 "Posting TXDW interrupt because TADV timer expired\n");
         postInterrupt(iGbReg::IT_TXDW);
     }

     EventFunctionWrapper tadvEvent;

     // Event and function to deal with TIDV timer expiring
     void tidvProcess() {
         txDescCache.writeback(0);
         DPRINTF(EthernetIntr,
                 "Posting TXDW interrupt because TIDV timer expired\n");
         postInterrupt(iGbReg::IT_TXDW);
     }
     EventFunctionWrapper tidvEvent;

     // Main event to tick the device
     void tick();
     EventFunctionWrapper tickEvent;


     uint64_t macAddr;

     void rxStateMachine();
     void txStateMachine();
     void txWire();

     /** Write an interrupt into the interrupt pending register and check mask
      * and interrupt limit timer before sending interrupt to CPU
      * @param t the type of interrupt we are posting
      * @param now should we ignore the interrupt limiting timer
      */
     void postInterrupt(iGbReg::IntTypes t, bool now = false);

     /** Check and see if changes to the mask register have caused an interrupt
      * to need to be sent or perhaps removed an interrupt cause.
      */
     void chkInterrupt();

     /** Send an interrupt to the cpu
      */
     void delayIntEvent();
     void cpuPostInt();
     // Event to moderate interrupts
     EventFunctionWrapper interEvent;

     /** Clear the interupt line to the cpu
      */
     void cpuClearInt();

     Tick intClock() { return SimClock::Int::ns * 1024; }

     /** This function is used to restart the clock so it can handle things like
      * draining and resume in one place. */
     void restartClock();

     /** Check if all the draining things that need to occur have occured and
      * handle the drain event if so.
      */
     void checkDrain();

     void anBegin(std::string sm, std::string st, int flags = CPA::FL_NONE) {
         if (cpa)
             cpa->hwBegin((CPA::flags)flags, sys, macAddr, sm, st);
     }

     void anQ(std::string sm, std::string q) {
         if (cpa)
             cpa->hwQ(CPA::FL_NONE, sys, macAddr, sm, q, macAddr);
     }

     void anDq(std::string sm, std::string q) {
         if (cpa)
             cpa->hwDq(CPA::FL_NONE, sys, macAddr, sm, q, macAddr);
     }

     void anPq(std::string sm, std::string q, int num = 1) {
         if (cpa)
             cpa->hwPq(CPA::FL_NONE, sys, macAddr, sm, q, macAddr, NULL, num);
     }

     void anRq(std::string sm, std::string q, int num = 1) {
         if (cpa)
             cpa->hwRq(CPA::FL_NONE, sys, macAddr, sm, q, macAddr, NULL, num);
     }

     void anWe(std::string sm, std::string q) {
         if (cpa)
             cpa->hwWe(CPA::FL_NONE, sys, macAddr, sm, q, macAddr);
     }

     void anWf(std::string sm, std::string q) {
         if (cpa)
             cpa->hwWf(CPA::FL_NONE, sys, macAddr, sm, q, macAddr);
     }


     template<class T>
     class DescCache : public Serializable
     {
       protected:
         virtual Addr descBase() const = 0;
         virtual long descHead() const = 0;
         virtual long descTail() const = 0;
         virtual long descLen() const = 0;
         virtual void updateHead(long h) = 0;
         virtual void enableSm() = 0;
         virtual void actionAfterWb() {}
         virtual void fetchAfterWb() = 0;

         typedef std::deque<T *> CacheType;
         CacheType usedCache;
         CacheType unusedCache;

         T *fetchBuf;
         T *wbBuf;

         // Pointer to the device we cache for
         IGbE *igbe;

         // Name of this  descriptor cache
         std::string _name;

         // How far we've cached
         int cachePnt;

         // The size of the descriptor cache
         int size;

         // How many descriptors we are currently fetching
         int curFetching;

         // How many descriptors we are currently writing back
         int wbOut;

         // if the we wrote back to the end of the descriptor ring and are going
         // to have to wrap and write more
         bool moreToWb;

         // What the alignment is of the next descriptor writeback
         Addr wbAlignment;

         /** The packet that is currently being dmad to memory if any */
         EthPacketPtr pktPtr;

         /** Shortcut for DMA address translation */
         Addr pciToDma(Addr a) { return igbe->pciToDma(a); }

       public:
         /** Annotate sm*/
         std::string annSmFetch, annSmWb, annUnusedDescQ, annUsedCacheQ,
             annUsedDescQ, annUnusedCacheQ, annDescQ;

         DescCache(IGbE *i, const std::string n, int s);
         virtual ~DescCache();

         std::string name() { return _name; }

         /** If the address/len/head change when we've got descriptors that are
          * dirty that is very bad. This function checks that we don't and if we
          * do panics.
          */
         void areaChanged();

         void writeback(Addr aMask);
         void writeback1();
         EventFunctionWrapper wbDelayEvent;

         /** Fetch a chunk of descriptors into the descriptor cache.
          * Calls fetchComplete when the memory system returns the data
          */
         void fetchDescriptors();
         void fetchDescriptors1();
         EventFunctionWrapper fetchDelayEvent;

         /** Called by event when dma to read descriptors is completed
          */
         void fetchComplete();
         EventFunctionWrapper fetchEvent;

         /** Called by event when dma to writeback descriptors is completed
          */
         void wbComplete();
         EventFunctionWrapper wbEvent;

         /* Return the number of descriptors left in the ring, so the device has
          * a way to figure out if it needs to interrupt.
          */
         unsigned
         descLeft() const
         {
             unsigned left = unusedCache.size();
             if (cachePnt > descTail())
                 left += (descLen() - cachePnt + descTail());
             else
                 left += (descTail() - cachePnt);

             return left;
         }

         /* Return the number of descriptors used and not written back.
          */
         unsigned descUsed() const { return usedCache.size(); }

         /* Return the number of cache unused descriptors we have. */
         unsigned descUnused() const { return unusedCache.size(); }

         /* Get into a state where the descriptor address/head/etc colud be
          * changed */
         void reset();


         void serialize(CheckpointOut &cp) const override;
         void unserialize(CheckpointIn &cp) override;

         virtual bool hasOutstandingEvents() {
             return wbEvent.scheduled() || fetchEvent.scheduled();
         }

     };


     class RxDescCache : public DescCache<iGbReg::RxDesc>
     {
       protected:
         Addr descBase() const override { return igbe->regs.rdba(); }
         long descHead() const override { return igbe->regs.rdh(); }
         long descLen() const override { return igbe->regs.rdlen() >> 4; }
         long descTail() const override { return igbe->regs.rdt(); }
         void updateHead(long h) override { igbe->regs.rdh(h); }
         void enableSm() override;
         void fetchAfterWb() override {
             if (!igbe->rxTick && igbe->drainState() == DrainState::Running)
                 fetchDescriptors();
         }

         bool pktDone;

         /** Variable to head with header/data completion events */
         int splitCount;

         /** Bytes of packet that have been copied, so we know when to
             set EOP */
         unsigned bytesCopied;

       public:
         RxDescCache(IGbE *i, std::string n, int s);

         /** Write the given packet into the buffer(s) pointed to by the
          * descriptor and update the book keeping. Should only be called when
          * there are no dma's pending.
          * @param packet ethernet packet to write
          * @param pkt_offset bytes already copied from the packet to memory
          * @return pkt_offset + number of bytes copied during this call
          */
         int writePacket(EthPacketPtr packet, int pkt_offset);

         /** Called by event when dma to write packet is completed
          */
         void pktComplete();

         /** Check if the dma on the packet has completed and RX state machine
          * can continue
          */
         bool packetDone();

         EventFunctionWrapper pktEvent;

         // Event to handle issuing header and data write at the same time
         // and only callking pktComplete() when both are completed
         void pktSplitDone();
         EventFunctionWrapper pktHdrEvent;
         EventFunctionWrapper pktDataEvent;

         bool hasOutstandingEvents() override;

         void serialize(CheckpointOut &cp) const override;
         void unserialize(CheckpointIn &cp) override;
     };
     friend class RxDescCache;

     RxDescCache rxDescCache;

     class TxDescCache  : public DescCache<iGbReg::TxDesc>
     {
       protected:
         Addr descBase() const override { return igbe->regs.tdba(); }
         long descHead() const override { return igbe->regs.tdh(); }
         long descTail() const override { return igbe->regs.tdt(); }
         long descLen() const override { return igbe->regs.tdlen() >> 4; }
         void updateHead(long h) override { igbe->regs.tdh(h); }
         void enableSm() override;
         void actionAfterWb() override;
         void fetchAfterWb() override {
             if (!igbe->txTick && igbe->drainState() == DrainState::Running)
                 fetchDescriptors();
         }


         bool pktDone;
         bool isTcp;
         bool pktWaiting;
         bool pktMultiDesc;
         Addr completionAddress;
         bool completionEnabled;
         uint32_t descEnd;


         // tso variables
         bool useTso;
         Addr tsoHeaderLen;
         Addr tsoMss;
         Addr tsoTotalLen;
         Addr tsoUsedLen;
         Addr tsoPrevSeq;
         Addr tsoPktPayloadBytes;
         bool tsoLoadedHeader;
         bool tsoPktHasHeader;
         uint8_t tsoHeader[256];
         Addr tsoDescBytesUsed;
         Addr tsoCopyBytes;
         int tsoPkts;

       public:
         TxDescCache(IGbE *i, std::string n, int s);

         /** Tell the cache to DMA a packet from main memory into its buffer and
          * return the size the of the packet to reserve space in tx fifo.
          * @return size of the packet
          */
         unsigned getPacketSize(EthPacketPtr p);
         void getPacketData(EthPacketPtr p);
         void processContextDesc();

         /** Return the number of dsecriptors in a cache block for threshold
          * operations.
          */
         unsigned
         descInBlock(unsigned num_desc)
         {
             return num_desc / igbe->cacheBlockSize() / sizeof(iGbReg::TxDesc);
         }

         /** Ask if the packet has been transfered so the state machine can give
          * it to the fifo.
          * @return packet available in descriptor cache
          */
         bool packetAvailable();

         /** Ask if we are still waiting for the packet to be transfered.
          * @return packet still in transit.
          */
         bool packetWaiting() { return pktWaiting; }

         /** Ask if this packet is composed of multiple descriptors
          * so even if we've got data, we need to wait for more before
          * we can send it out.
          * @return packet can't be sent out because it's a multi-descriptor
          * packet
          */
         bool packetMultiDesc() { return pktMultiDesc;}

         /** Called by event when dma to write packet is completed
          */
         void pktComplete();
         EventFunctionWrapper pktEvent;

         void headerComplete();
         EventFunctionWrapper headerEvent;


         void completionWriteback(Addr a, bool enabled) {
             DPRINTF(EthernetDesc,
                     "Completion writeback Addr: %#x enabled: %d\n",
                     a, enabled);
             completionAddress = a;
             completionEnabled = enabled;
         }

         bool hasOutstandingEvents() override;

         void nullCallback() {
             DPRINTF(EthernetDesc, "Completion writeback complete\n");
         }
         EventFunctionWrapper nullEvent;

         void serialize(CheckpointOut &cp) const override;
         void unserialize(CheckpointIn &cp) override;
     };

     friend class TxDescCache;

     TxDescCache txDescCache;

   public:
     typedef IGbEParams Params;
     const Params *
     params() const {
         return dynamic_cast<const Params *>(_params);
     }

     IGbE(const Params *params);
     ~IGbE();
     void init() override;

     EtherInt *getEthPort(const std::string &if_name, int idx) override;

     Tick lastInterrupt;

     Tick read(PacketPtr pkt) override;
     Tick write(PacketPtr pkt) override;

     Tick writeConfig(PacketPtr pkt) override;

     bool ethRxPkt(EthPacketPtr packet);
     void ethTxDone();

     void serialize(CheckpointOut &cp) const override;
     void unserialize(CheckpointIn &cp) override;

     DrainState drain() override;
     void drainResume() override;

 };

 class IGbEInt : public EtherInt
 {
   private:
     IGbE *dev;

   public:
     IGbEInt(const std::string &name, IGbE *d)
         : EtherInt(name), dev(d)
     { }

     virtual bool recvPacket(EthPacketPtr pkt) { return dev->ethRxPkt(pkt); }
     virtual void sendDone() { dev->ethTxDone(); }
 };

 #endif //__DEV_NET_I8254XGBE_HH__
	/*
	* 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
	* Device model for Intel's 8254x line of gigabit ethernet controllers.
	*/

	#ifndef __DEV_NET_I8254XGBE_HH__
	#define __DEV_NET_I8254XGBE_HH__

	#include <deque>
	#include <string>

	#include "base/cp_annotate.hh"
	#include "base/inet.hh"
	#include "debug/EthernetDesc.hh"
	#include "debug/EthernetIntr.hh"
	#include "dev/net/etherdevice.hh"
	#include "dev/net/etherint.hh"
	#include "dev/net/etherpkt.hh"
	#include "dev/net/i8254xGBe_defs.hh"
	#include "dev/net/pktfifo.hh"
	#include "dev/pci/device.hh"
	#include "params/IGbE.hh"
	#include "sim/eventq.hh"

	class IGbEInt;

	class IGbE : public EtherDevice
	{
	private:
	IGbEInt *etherInt;
	CPA *cpa;

	// device registers
	iGbReg::Regs regs;

	// eeprom data, status and control bits
	int eeOpBits, eeAddrBits, eeDataBits;
	uint8_t eeOpcode, eeAddr;
	uint16_t flash[iGbReg::EEPROM_SIZE];

	// packet fifos
	PacketFifo rxFifo;
	PacketFifo txFifo;

	// Packet that we are currently putting into the txFifo
	EthPacketPtr txPacket;

	// Should to Rx/Tx State machine tick?
	bool inTick;
	bool rxTick;
	bool txTick;
	bool txFifoTick;

	bool rxDmaPacket;

	// Number of bytes copied from current RX packet
	unsigned pktOffset;

	// Delays in managaging descriptors
	Tick fetchDelay, wbDelay;
	Tick fetchCompDelay, wbCompDelay;
	Tick rxWriteDelay, txReadDelay;

	// Event and function to deal with RDTR timer expiring
	void rdtrProcess() {
	rxDescCache.writeback(0);
	DPRINTF(EthernetIntr,
	"Posting RXT interrupt because RDTR timer expired\n");
	postInterrupt(iGbReg::IT_RXT);
	}

	EventFunctionWrapper rdtrEvent;

	// Event and function to deal with RADV timer expiring
	void radvProcess() {
	rxDescCache.writeback(0);
	DPRINTF(EthernetIntr,
	"Posting RXT interrupt because RADV timer expired\n");
	postInterrupt(iGbReg::IT_RXT);
	}

	EventFunctionWrapper radvEvent;

	// Event and function to deal with TADV timer expiring
	void tadvProcess() {
	txDescCache.writeback(0);
	DPRINTF(EthernetIntr,
	"Posting TXDW interrupt because TADV timer expired\n");
	postInterrupt(iGbReg::IT_TXDW);
	}

	EventFunctionWrapper tadvEvent;

	// Event and function to deal with TIDV timer expiring
	void tidvProcess() {
	txDescCache.writeback(0);
	DPRINTF(EthernetIntr,
	"Posting TXDW interrupt because TIDV timer expired\n");
	postInterrupt(iGbReg::IT_TXDW);
	}
	EventFunctionWrapper tidvEvent;

	// Main event to tick the device
	void tick();
	EventFunctionWrapper tickEvent;


	uint64_t macAddr;

	void rxStateMachine();
	void txStateMachine();
	void txWire();

	/** Write an interrupt into the interrupt pending register and check mask
	* and interrupt limit timer before sending interrupt to CPU
	* @param t the type of interrupt we are posting
	* @param now should we ignore the interrupt limiting timer
	*/
	void postInterrupt(iGbReg::IntTypes t, bool now = false);

	/** Check and see if changes to the mask register have caused an interrupt
	* to need to be sent or perhaps removed an interrupt cause.
	*/
	void chkInterrupt();

	/** Send an interrupt to the cpu
	*/
	void delayIntEvent();
	void cpuPostInt();
	// Event to moderate interrupts
	EventFunctionWrapper interEvent;

	/** Clear the interupt line to the cpu
	*/
	void cpuClearInt();

	Tick intClock() { return SimClock::Int::ns * 1024; }

	/** This function is used to restart the clock so it can handle things like
	* draining and resume in one place. */
	void restartClock();

	/** Check if all the draining things that need to occur have occured and
	* handle the drain event if so.
	*/
	void checkDrain();

	void anBegin(std::string sm, std::string st, int flags = CPA::FL_NONE) {
	if (cpa)
	cpa->hwBegin((CPA::flags)flags, sys, macAddr, sm, st);
	}

	void anQ(std::string sm, std::string q) {
	if (cpa)
	cpa->hwQ(CPA::FL_NONE, sys, macAddr, sm, q, macAddr);
	}

	void anDq(std::string sm, std::string q) {
	if (cpa)
	cpa->hwDq(CPA::FL_NONE, sys, macAddr, sm, q, macAddr);
	}

	void anPq(std::string sm, std::string q, int num = 1) {
	if (cpa)
	cpa->hwPq(CPA::FL_NONE, sys, macAddr, sm, q, macAddr, NULL, num);
	}

	void anRq(std::string sm, std::string q, int num = 1) {
	if (cpa)
	cpa->hwRq(CPA::FL_NONE, sys, macAddr, sm, q, macAddr, NULL, num);
	}

	void anWe(std::string sm, std::string q) {
	if (cpa)
	cpa->hwWe(CPA::FL_NONE, sys, macAddr, sm, q, macAddr);
	}

	void anWf(std::string sm, std::string q) {
	if (cpa)
	cpa->hwWf(CPA::FL_NONE, sys, macAddr, sm, q, macAddr);
	}


	template<class T>
	class DescCache : public Serializable
	{
	protected:
	virtual Addr descBase() const = 0;
	virtual long descHead() const = 0;
	virtual long descTail() const = 0;
	virtual long descLen() const = 0;
	virtual void updateHead(long h) = 0;
	virtual void enableSm() = 0;
	virtual void actionAfterWb() {}
	virtual void fetchAfterWb() = 0;

	typedef std::deque<T *> CacheType;
	CacheType usedCache;
	CacheType unusedCache;

	T *fetchBuf;
	T *wbBuf;

	// Pointer to the device we cache for
	IGbE *igbe;

	// Name of this descriptor cache
	std::string _name;

	// How far we've cached
	int cachePnt;

	// The size of the descriptor cache
	int size;

	// How many descriptors we are currently fetching
	int curFetching;

	// How many descriptors we are currently writing back
	int wbOut;

	// if the we wrote back to the end of the descriptor ring and are going
	// to have to wrap and write more
	bool moreToWb;

	// What the alignment is of the next descriptor writeback
	Addr wbAlignment;

	/** The packet that is currently being dmad to memory if any */
	EthPacketPtr pktPtr;

	/** Shortcut for DMA address translation */
	Addr pciToDma(Addr a) { return igbe->pciToDma(a); }

	public:
	/** Annotate sm*/
	std::string annSmFetch, annSmWb, annUnusedDescQ, annUsedCacheQ,
	annUsedDescQ, annUnusedCacheQ, annDescQ;

	DescCache(IGbE *i, const std::string n, int s);
	virtual ~DescCache();

	std::string name() { return _name; }

	/** If the address/len/head change when we've got descriptors that are
	* dirty that is very bad. This function checks that we don't and if we
	* do panics.
	*/
	void areaChanged();

	void writeback(Addr aMask);
	void writeback1();
	EventFunctionWrapper wbDelayEvent;

	/** Fetch a chunk of descriptors into the descriptor cache.
	* Calls fetchComplete when the memory system returns the data
	*/
	void fetchDescriptors();
	void fetchDescriptors1();
	EventFunctionWrapper fetchDelayEvent;

	/** Called by event when dma to read descriptors is completed
	*/
	void fetchComplete();
	EventFunctionWrapper fetchEvent;

	/** Called by event when dma to writeback descriptors is completed
	*/
	void wbComplete();
	EventFunctionWrapper wbEvent;

	/* Return the number of descriptors left in the ring, so the device has
	* a way to figure out if it needs to interrupt.
	*/
	unsigned
	descLeft() const
	{
	unsigned left = unusedCache.size();
	if (cachePnt > descTail())
	left += (descLen() - cachePnt + descTail());
	else
	left += (descTail() - cachePnt);

	return left;
	}

	/* Return the number of descriptors used and not written back.
	*/
	unsigned descUsed() const { return usedCache.size(); }

	/* Return the number of cache unused descriptors we have. */
	unsigned descUnused() const { return unusedCache.size(); }

	/* Get into a state where the descriptor address/head/etc colud be
	* changed */
	void reset();


	void serialize(CheckpointOut &cp) const override;
	void unserialize(CheckpointIn &cp) override;

	virtual bool hasOutstandingEvents() {
	return wbEvent.scheduled() \|\| fetchEvent.scheduled();
	}

	};


	class RxDescCache : public DescCache<iGbReg::RxDesc>
	{
	protected:
	Addr descBase() const override { return igbe->regs.rdba(); }
	long descHead() const override { return igbe->regs.rdh(); }
	long descLen() const override { return igbe->regs.rdlen() >> 4; }
	long descTail() const override { return igbe->regs.rdt(); }
	void updateHead(long h) override { igbe->regs.rdh(h); }
	void enableSm() override;
	void fetchAfterWb() override {
	if (!igbe->rxTick && igbe->drainState() == DrainState::Running)
	fetchDescriptors();
	}

	bool pktDone;

	/** Variable to head with header/data completion events */
	int splitCount;

	/** Bytes of packet that have been copied, so we know when to
	set EOP */
	unsigned bytesCopied;

	public:
	RxDescCache(IGbE *i, std::string n, int s);

	/** Write the given packet into the buffer(s) pointed to by the
	* descriptor and update the book keeping. Should only be called when
	* there are no dma's pending.
	* @param packet ethernet packet to write
	* @param pkt_offset bytes already copied from the packet to memory
	* @return pkt_offset + number of bytes copied during this call
	*/
	int writePacket(EthPacketPtr packet, int pkt_offset);

	/** Called by event when dma to write packet is completed
	*/
	void pktComplete();

	/** Check if the dma on the packet has completed and RX state machine
	* can continue
	*/
	bool packetDone();

	EventFunctionWrapper pktEvent;

	// Event to handle issuing header and data write at the same time
	// and only callking pktComplete() when both are completed
	void pktSplitDone();
	EventFunctionWrapper pktHdrEvent;
	EventFunctionWrapper pktDataEvent;

	bool hasOutstandingEvents() override;

	void serialize(CheckpointOut &cp) const override;
	void unserialize(CheckpointIn &cp) override;
	};
	friend class RxDescCache;

	RxDescCache rxDescCache;

	class TxDescCache : public DescCache<iGbReg::TxDesc>
	{
	protected:
	Addr descBase() const override { return igbe->regs.tdba(); }
	long descHead() const override { return igbe->regs.tdh(); }
	long descTail() const override { return igbe->regs.tdt(); }
	long descLen() const override { return igbe->regs.tdlen() >> 4; }
	void updateHead(long h) override { igbe->regs.tdh(h); }
	void enableSm() override;
	void actionAfterWb() override;
	void fetchAfterWb() override {
	if (!igbe->txTick && igbe->drainState() == DrainState::Running)
	fetchDescriptors();
	}



	bool pktDone;
	bool isTcp;
	bool pktWaiting;
	bool pktMultiDesc;
	Addr completionAddress;
	bool completionEnabled;
	uint32_t descEnd;


	// tso variables
	bool useTso;
	Addr tsoHeaderLen;
	Addr tsoMss;
	Addr tsoTotalLen;
	Addr tsoUsedLen;
	Addr tsoPrevSeq;
	Addr tsoPktPayloadBytes;
	bool tsoLoadedHeader;
	bool tsoPktHasHeader;
	uint8_t tsoHeader[256];
	Addr tsoDescBytesUsed;
	Addr tsoCopyBytes;
	int tsoPkts;

	public:
	TxDescCache(IGbE *i, std::string n, int s);

	/** Tell the cache to DMA a packet from main memory into its buffer and
	* return the size the of the packet to reserve space in tx fifo.
	* @return size of the packet
	*/
	unsigned getPacketSize(EthPacketPtr p);
	void getPacketData(EthPacketPtr p);
	void processContextDesc();

	/** Return the number of dsecriptors in a cache block for threshold
	* operations.
	*/
	unsigned
	descInBlock(unsigned num_desc)
	{
	return num_desc / igbe->cacheBlockSize() / sizeof(iGbReg::TxDesc);
	}

	/** Ask if the packet has been transfered so the state machine can give
	* it to the fifo.
	* @return packet available in descriptor cache
	*/
	bool packetAvailable();

	/** Ask if we are still waiting for the packet to be transfered.
	* @return packet still in transit.
	*/
	bool packetWaiting() { return pktWaiting; }

	/** Ask if this packet is composed of multiple descriptors
	* so even if we've got data, we need to wait for more before
	* we can send it out.
	* @return packet can't be sent out because it's a multi-descriptor
	* packet
	*/
	bool packetMultiDesc() { return pktMultiDesc;}

	/** Called by event when dma to write packet is completed
	*/
	void pktComplete();
	EventFunctionWrapper pktEvent;

	void headerComplete();
	EventFunctionWrapper headerEvent;


	void completionWriteback(Addr a, bool enabled) {
	DPRINTF(EthernetDesc,
	"Completion writeback Addr: %#x enabled: %d\n",
	a, enabled);
	completionAddress = a;
	completionEnabled = enabled;
	}

	bool hasOutstandingEvents() override;

	void nullCallback() {
	DPRINTF(EthernetDesc, "Completion writeback complete\n");
	}
	EventFunctionWrapper nullEvent;

	void serialize(CheckpointOut &cp) const override;
	void unserialize(CheckpointIn &cp) override;
	};

	friend class TxDescCache;

	TxDescCache txDescCache;

	public:
	typedef IGbEParams Params;
	const Params *
	params() const {
	return dynamic_cast<const Params *>(_params);
	}

	IGbE(const Params *params);
	~IGbE();
	void init() override;

	EtherInt *getEthPort(const std::string &if_name, int idx) override;

	Tick lastInterrupt;

	Tick read(PacketPtr pkt) override;
	Tick write(PacketPtr pkt) override;

	Tick writeConfig(PacketPtr pkt) override;

	bool ethRxPkt(EthPacketPtr packet);
	void ethTxDone();

	void serialize(CheckpointOut &cp) const override;
	void unserialize(CheckpointIn &cp) override;

	DrainState drain() override;
	void drainResume() override;

	};

	class IGbEInt : public EtherInt
	{
	private:
	IGbE *dev;

	public:
	IGbEInt(const std::string &name, IGbE *d)
	: EtherInt(name), dev(d)
	{ }

	virtual bool recvPacket(EthPacketPtr pkt) { return dev->ethRxPkt(pkt); }
	virtual void sendDone() { dev->ethTxDone(); }
	};

	#endif //__DEV_NET_I8254XGBE_HH__