eth_wishbone.v

此文档为采用FPGA实现的以太网MAC层

// signals are used for proper selection of the start byte (TxData and TxByteCnt) are
// set by this two bits.
always @ (posedge WB_CLK_I or posedge Reset)
begin
  if(Reset)
    TxPointerLSB[1:0] <=#Tp 0;
  else
  if(TxEn & TxEn_q & TxPointerRead)
    TxPointerLSB[1:0] <=#Tp ram_do[1:0];
end


// Latching 2 MSB bits of the buffer descriptor. 
// After the read access, TxLength needs to be decremented for the number of the valid
// bytes (1 to 4 bytes are valid in the first word). After the first read all bytes are 
// valid so this two bits are reset to zero. 
always @ (posedge WB_CLK_I or posedge Reset)
begin
  if(Reset)
    TxPointerLSB_rst[1:0] <=#Tp 0;
  else
  if(TxEn & TxEn_q & TxPointerRead)
    TxPointerLSB_rst[1:0] <=#Tp ram_do[1:0];
  else
  if(MasterWbTX & m_wb_ack_i)                 // After first access pointer is word alligned
    TxPointerLSB_rst[1:0] <=#Tp 0;
end


reg  [3:0] RxByteSel;
wire MasterAccessFinished;


always @ (posedge WB_CLK_I or posedge Reset)
begin
  if(Reset)
    BlockingIncrementTxPointer <=#Tp 0;
  else
  if(MasterAccessFinished)
    BlockingIncrementTxPointer <=#Tp 0;
  else
  if(IncrTxPointer)
    BlockingIncrementTxPointer <=#Tp 1'b1;
end


wire TxBufferAlmostFull;
wire TxBufferFull;
wire TxBufferEmpty;
wire TxBufferAlmostEmpty;
wire SetReadTxDataFromMemory;

reg BlockReadTxDataFromMemory;

assign SetReadTxDataFromMemory = TxEn & TxEn_q & TxPointerRead;

always @ (posedge WB_CLK_I or posedge Reset)
begin
  if(Reset)
    ReadTxDataFromMemory <=#Tp 1'b0;
  else
  if(TxLengthEq0 | TxAbortPulse | TxRetryPulse)
    ReadTxDataFromMemory <=#Tp 1'b0;
  else
  if(SetReadTxDataFromMemory)
    ReadTxDataFromMemory <=#Tp 1'b1;
end

reg tx_burst_en;
reg rx_burst_en;

wire ReadTxDataFromMemory_2 = ReadTxDataFromMemory & ~BlockReadTxDataFromMemory;
wire tx_burst = ReadTxDataFromMemory_2 & tx_burst_en;

wire [31:0] TxData_wb;
wire ReadTxDataFromFifo_wb;

always @ (posedge WB_CLK_I or posedge Reset)
begin
  if(Reset)
    BlockReadTxDataFromMemory <=#Tp 1'b0;
  else
  if((TxBufferAlmostFull | TxLength <= 4)& MasterWbTX & (~cyc_cleared) & (!(TxAbortPacket_NotCleared | TxRetryPacket_NotCleared)))
    BlockReadTxDataFromMemory <=#Tp 1'b1;
  else
  if(ReadTxDataFromFifo_wb | TxDonePacket | TxAbortPacket | TxRetryPacket)
    BlockReadTxDataFromMemory <=#Tp 1'b0;
end


assign MasterAccessFinished = m_wb_ack_i | m_wb_err_i;
wire [`ETH_TX_FIFO_CNT_WIDTH-1:0] txfifo_cnt;
wire [`ETH_RX_FIFO_CNT_WIDTH-1:0] rxfifo_cnt;
reg  [`ETH_BURST_CNT_WIDTH-1:0] tx_burst_cnt;
reg  [`ETH_BURST_CNT_WIDTH-1:0] rx_burst_cnt;

wire rx_burst;
wire enough_data_in_rxfifo_for_burst;
wire enough_data_in_rxfifo_for_burst_plus1;

// Enabling master wishbone access to the memory for two devices TX and RX.
always @ (posedge WB_CLK_I or posedge Reset)
begin
  if(Reset)
    begin
      MasterWbTX <=#Tp 1'b0;
      MasterWbRX <=#Tp 1'b0;
      m_wb_adr_o <=#Tp 30'h0;
      m_wb_cyc_o <=#Tp 1'b0;
      m_wb_we_o  <=#Tp 1'b0;
      m_wb_sel_o <=#Tp 4'h0;
      cyc_cleared<=#Tp 1'b0;
      tx_burst_cnt<=#Tp 0;
      rx_burst_cnt<=#Tp 0;
      IncrTxPointer<=#Tp 1'b0;
      tx_burst_en<=#Tp 1'b1;
      rx_burst_en<=#Tp 1'b0;
      `ifdef ETH_WISHBONE_B3
        m_wb_cti_o <=#Tp 3'b0;
      `endif
    end
  else
    begin
      // Switching between two stages depends on enable signals
      casex ({MasterWbTX, MasterWbRX, ReadTxDataFromMemory_2, WriteRxDataToMemory, MasterAccessFinished, cyc_cleared, tx_burst, rx_burst})  // synopsys parallel_case
        8'b00_10_00_10,             // Idle and MRB needed
        8'b10_1x_10_1x,             // MRB continues
        8'b10_10_01_10,             // Clear (previously MR) and MRB needed
        8'b01_1x_01_1x :            // Clear (previously MW) and MRB needed
          begin
            MasterWbTX <=#Tp 1'b1;  // tx burst
            MasterWbRX <=#Tp 1'b0;
            m_wb_cyc_o <=#Tp 1'b1;
            m_wb_we_o  <=#Tp 1'b0;
            m_wb_sel_o <=#Tp 4'hf;
            cyc_cleared<=#Tp 1'b0;
            IncrTxPointer<=#Tp 1'b1;
            tx_burst_cnt <=#Tp tx_burst_cnt+3'h1;
            if(tx_burst_cnt==0)
              m_wb_adr_o <=#Tp TxPointerMSB;
            else
              m_wb_adr_o <=#Tp m_wb_adr_o+1'b1;

            if(tx_burst_cnt==(`ETH_BURST_LENGTH-1))
              begin
                tx_burst_en<=#Tp 1'b0;
              `ifdef ETH_WISHBONE_B3
                m_wb_cti_o <=#Tp 3'b111;
              `endif
              end
            else
              begin
              `ifdef ETH_WISHBONE_B3
                m_wb_cti_o <=#Tp 3'b010;
              `endif
              end
          end
        8'b00_x1_00_x1,             // Idle and MWB needed
        8'b01_x1_10_x1,             // MWB continues
        8'b01_01_01_01,             // Clear (previously MW) and MWB needed
        8'b10_x1_01_x1 :            // Clear (previously MR) and MWB needed
          begin
            MasterWbTX <=#Tp 1'b0;  // rx burst
            MasterWbRX <=#Tp 1'b1;
            m_wb_cyc_o <=#Tp 1'b1;
            m_wb_we_o  <=#Tp 1'b1;
            m_wb_sel_o <=#Tp RxByteSel;
            IncrTxPointer<=#Tp 1'b0;
            cyc_cleared<=#Tp 1'b0;
            rx_burst_cnt <=#Tp rx_burst_cnt+3'h1;

            if(rx_burst_cnt==0)
              m_wb_adr_o <=#Tp RxPointerMSB;
            else
              m_wb_adr_o <=#Tp m_wb_adr_o+1'b1;

            if(rx_burst_cnt==(`ETH_BURST_LENGTH-1))
              begin
                rx_burst_en<=#Tp 1'b0;
              `ifdef ETH_WISHBONE_B3
                m_wb_cti_o <=#Tp 3'b111;
              `endif
              end
            else
              begin
              `ifdef ETH_WISHBONE_B3
                m_wb_cti_o <=#Tp 3'b010;
              `endif
              end
          end
        8'b00_x1_00_x0 :            // idle and MW is needed (data write to rx buffer)
          begin
            MasterWbTX <=#Tp 1'b0;
            MasterWbRX <=#Tp 1'b1;
            m_wb_adr_o <=#Tp RxPointerMSB;
            m_wb_cyc_o <=#Tp 1'b1;
            m_wb_we_o  <=#Tp 1'b1;
            m_wb_sel_o <=#Tp RxByteSel;
            IncrTxPointer<=#Tp 1'b0;
          end
        8'b00_10_00_00 :            // idle and MR is needed (data read from tx buffer)
          begin
            MasterWbTX <=#Tp 1'b1;
            MasterWbRX <=#Tp 1'b0;
            m_wb_adr_o <=#Tp TxPointerMSB;
            m_wb_cyc_o <=#Tp 1'b1;
            m_wb_we_o  <=#Tp 1'b0;
            m_wb_sel_o <=#Tp 4'hf;
            IncrTxPointer<=#Tp 1'b1;
          end
        8'b10_10_01_00,             // MR and MR is needed (data read from tx buffer)
        8'b01_1x_01_0x  :           // MW and MR is needed (data read from tx buffer)
          begin
            MasterWbTX <=#Tp 1'b1;
            MasterWbRX <=#Tp 1'b0;
            m_wb_adr_o <=#Tp TxPointerMSB;
            m_wb_cyc_o <=#Tp 1'b1;
            m_wb_we_o  <=#Tp 1'b0;
            m_wb_sel_o <=#Tp 4'hf;
            cyc_cleared<=#Tp 1'b0;
            IncrTxPointer<=#Tp 1'b1;
          end
        8'b01_01_01_00,             // MW and MW needed (data write to rx buffer)
        8'b10_x1_01_x0  :           // MR and MW is needed (data write to rx buffer)
          begin
            MasterWbTX <=#Tp 1'b0;
            MasterWbRX <=#Tp 1'b1;
            m_wb_adr_o <=#Tp RxPointerMSB;
            m_wb_cyc_o <=#Tp 1'b1;
            m_wb_we_o  <=#Tp 1'b1;
            m_wb_sel_o <=#Tp RxByteSel;
            cyc_cleared<=#Tp 1'b0;
            IncrTxPointer<=#Tp 1'b0;
          end
        8'b01_01_10_00,             // MW and MW needed (cycle is cleared between previous and next access)
        8'b01_1x_10_x0,             // MW and MW or MR or MRB needed (cycle is cleared between previous and next access)
        8'b10_10_10_00,             // MR and MR needed (cycle is cleared between previous and next access)
        8'b10_x1_10_0x :            // MR and MR or MW or MWB (cycle is cleared between previous and next access)
          begin
            m_wb_cyc_o <=#Tp 1'b0;  // whatever and master read or write is needed. We need to clear m_wb_cyc_o before next access is started
            cyc_cleared<=#Tp 1'b1;
            IncrTxPointer<=#Tp 1'b0;
            tx_burst_cnt<=#Tp 0;
            tx_burst_en<=#Tp txfifo_cnt<(`ETH_TX_FIFO_DEPTH-`ETH_BURST_LENGTH) & (TxLength>(`ETH_BURST_LENGTH*4+4));
            rx_burst_cnt<=#Tp 0;
            rx_burst_en<=#Tp MasterWbRX ? enough_data_in_rxfifo_for_burst_plus1 : enough_data_in_rxfifo_for_burst;  // Counter is not decremented, yet, so plus1 is used.
            `ifdef ETH_WISHBONE_B3
              m_wb_cti_o <=#Tp 3'b0;
            `endif
          end
        8'bxx_00_10_00,             // whatever and no master read or write is needed (ack or err comes finishing previous access)
        8'bxx_00_01_00 :            // Between cyc_cleared request was cleared
          begin
            MasterWbTX <=#Tp 1'b0;
            MasterWbRX <=#Tp 1'b0;
            m_wb_cyc_o <=#Tp 1'b0;
            cyc_cleared<=#Tp 1'b0;
            IncrTxPointer<=#Tp 1'b0;
            rx_burst_cnt<=#Tp 0;
            rx_burst_en<=#Tp MasterWbRX ? enough_data_in_rxfifo_for_burst_plus1 : enough_data_in_rxfifo_for_burst;  // Counter is not decremented, yet, so plus1 is used.
            `ifdef ETH_WISHBONE_B3
              m_wb_cti_o <=#Tp 3'b0;
            `endif
          end
        8'b00_00_00_00:             // whatever and no master read or write is needed (ack or err comes finishing previous access)
          begin
            tx_burst_cnt<=#Tp 0;
            tx_burst_en<=#Tp txfifo_cnt<(`ETH_TX_FIFO_DEPTH-`ETH_BURST_LENGTH) & (TxLength>(`ETH_BURST_LENGTH*4+4));
          end
        default:                    // Don't touch
          begin
            MasterWbTX <=#Tp MasterWbTX;
            MasterWbRX <=#Tp MasterWbRX;
            m_wb_cyc_o <=#Tp m_wb_cyc_o;
            m_wb_sel_o <=#Tp m_wb_sel_o;
            IncrTxPointer<=#Tp IncrTxPointer;
          end
      endcase
    end
end


wire TxFifoClear;

assign TxFifoClear = (TxAbortPacket | TxRetryPacket);

eth_fifo #(`ETH_TX_FIFO_DATA_WIDTH, `ETH_TX_FIFO_DEPTH, `ETH_TX_FIFO_CNT_WIDTH)
tx_fifo ( .data_in(m_wb_dat_i),                             .data_out(TxData_wb), 
          .clk(WB_CLK_I),                                   .reset(Reset), 
          .write(MasterWbTX & m_wb_ack_i),                  .read(ReadTxDataFromFifo_wb & ~TxBufferEmpty),
          .clear(TxFifoClear),                              .full(TxBufferFull), 
          .almost_full(TxBufferAlmostFull),                 .almost_empty(TxBufferAlmostEmpty), 
          .empty(TxBufferEmpty),                            .cnt(txfifo_cnt)
        );


reg StartOccured;
reg TxStartFrm_sync1;
reg TxStartFrm_sync2;
reg TxStartFrm_syncb1;
reg TxStartFrm_syncb2;



// Start: Generation of the TxStartFrm_wb which is then synchronized to the MTxClk
always @ (posedge WB_CLK_I or posedge Reset)
begin
  if(Reset)
    TxStartFrm_wb <=#Tp 1'b0;
  else
  if(TxBDReady & ~StartOccured & (TxBufferFull | TxLengthEq0))
    TxStartFrm_wb <=#Tp 1'b1;
  else
  if(TxStartFrm_syncb2)
    TxStartFrm_wb <=#Tp 1'b0;
end

// StartOccured: TxStartFrm_wb occurs only ones at the beginning. Then it's blocked.
always @ (posedge WB_CLK_I or posedge Reset)
begin
  if(Reset)
    StartOccured <=#Tp 1'b0;
  else
  if(TxStartFrm_wb)
    StartOccured <=#Tp 1'b1;
  else
  if(ResetTxBDReady)
    StartOccured <=#Tp 1'b0;
end

// Synchronizing TxStartFrm_wb to MTxClk
always @ (posedge MTxClk or posedge Reset)
begin
  if(Reset)
    TxStartFrm_sync1 <=#Tp 1'b0;
  else
    TxStartFrm_sync1 <=#Tp TxStartFrm_wb;
end

always @ (posedge MTxClk or posedge Reset)
begin
  if(Reset)
    TxStartFrm_sync2 <=#Tp 1'b0;
  else
    TxStartFrm_sync2 <=#Tp TxStartFrm_sync1;
end

always @ (posedge WB_CLK_I or posedge Reset)
begin
  if(Reset)
    TxStartFrm_syncb1 <=#Tp 1'b0;
  else
    TxStartFrm_syncb1 <=#Tp TxStartFrm_sync2;
end

always @ (posedge WB_CLK_I or posedge Reset)
begin
  if(Reset)
    TxStartFrm_syncb2 <=#Tp 1'b0;
  else
    TxStartFrm_syncb2 <=#Tp TxStartFrm_syncb1;
end

always @ (posedge MTxClk or posedge Reset)
begin
  if(Reset)
    TxStartFrm <=#Tp 1'b0;
  else
  if(TxStartFrm_sync2)
    TxStartFrm <=#Tp 1'b1;
  else
  if(TxUsedData_q | ~TxStartFrm_sync2 & (TxRetry & (~TxRetry_q) | TxAbort & (~TxAbort_q)))
    TxStartFrm <=#Tp 1'b0;
end
// End: Generation of the TxStartFrm_wb which is then synchronized to the MTxClk


// TxEndFrm_wb: indicator of the end of frame
always @ (posedge WB_CLK_I or posedge Reset)
begin
  if(Reset)
    TxEndFrm_wb <=#Tp 1'b0;
  else
  if(TxLengthEq0 & TxBufferAlmostEmpty & TxUsedData)
    TxEndFrm_wb <=#Tp 1'b1;
  else
  if(TxRetryPulse | TxDonePulse | TxAbortPulse)
    TxEndFrm_wb <=#Tp 1'b0;
end


// Marks which bytes are valid within the word.
assign TxValidBytes = TxLengthLt4 ? TxLength[1:0] : 2'b0;

reg LatchValidBytes;
reg LatchValidBytes_q;

always @ (posedge WB_CLK_I or posedge Reset)
begin
  if(Reset)
    LatchValidBytes <=#Tp 1'b0;
  else
  if(TxLengthLt4 & TxBDReady)
    LatchValidBytes <=#Tp 1'b1;
  else
    LatchValidBytes <=#Tp 1'b0;
end

always @ (posedge WB_CLK_I or posedge Reset)
begin
  if(Reset)
    LatchValidBytes_q <=#Tp 1'b0;
  else
    LatchValidBytes_q <=#Tp LatchValidBytes;
end


// Latching valid bytes
always @ (posedge WB_CLK_I or posedge Reset)
begin
  if(Reset)
    TxValidBytesLatched <=#Tp 2'h0;
  else
  if(LatchValidBytes & ~LatchValidBytes_q)
    TxValidBytesLatched <=#Tp TxValidBytes;
  else
  if(TxRetryPulse | TxDonePulse | TxAbortPulse)
    TxValidBytesLatched <=#Tp 2'h0;
end


assign TxIRQEn          = TxStatus[14];
assign WrapTxStatusBit  = TxStatus[13];
assign PerPacketPad     = TxStatus[12];
assign PerPacketCrcEn   = TxStatus[11];


assign RxIRQEn         = RxStatus[14];
assign WrapRxStatusBit = RxStatus[13];


// Temporary Tx and Rx buffer descriptor address 
assign TempTxBDAddress[7:1] = {7{ TxStatusWrite     & ~WrapTxStatusBit}}   & (TxBDAddress + 1'b1) ; // Tx BD increment or wrap (last BD)
assign TempRxBDAddress[7:1] = {7{ WrapRxStatusBit}} & (r_TxBDNum[6:0])     | // Using first Rx BD
                              {7{~WrapRxStatusBit}} & (RxBDAddress + 1'b1) ; // Using next Rx BD (incremenrement address)


// Latching Tx buffer descriptor address
always @ (posedge WB_CLK_I or posedge Reset)
begin
  if(Reset)
    TxBDAddress <=#Tp 7'h0;
  else if (r_TxEn & (~r_TxEn_q))
    TxBDAddress <=#Tp 7'h0;
  else if (TxStatusWrite)
    TxBDAddress <=#Tp TempTxBDAddress;
end


// Latching Rx buffer descriptor address
always @ (posedge WB_CLK_I or posedge Reset)
begin
  if(Reset)