pci_wb_slave.v

这是用pci-wishbone核和16450串口核在xilinx的fpga上实现的串口程序

                begin
                    n_state = S_IDLE ;
                    del_done = 1'b1 ;
                    wbr_fifo_flush = ~wbr_fifo_empty_in ;
                end
                else
                begin
                    n_state          = S_READ ;
                end
            end // S_READ

    S_CONF_WRITE:  begin
                        `ifdef HOST
                            wbw_data_out_sel = SEL_CCYC_ADDR ;
                            del_req          = do_ccyc_req && ~burst_transfer  ;
                            del_done         = do_ccyc_comp && ~burst_transfer ;
                            del_in_progress  = do_ccyc_comp && ~burst_transfer ;
                        `endif

                        n_state         = S_IDLE ; // next state after configuration access is always idle

                        if ( burst_transfer )
                        begin
                            err = 1'b1 ;
                        end
                        else
                        begin
                            `ifdef HOST
                            if ( do_ccyc_req || (ccyc_hit && ~do_ccyc_comp))
                            begin
                                rty = 1'b1 ;
                            end
                            else
                            if ( do_ccyc_comp )
                            begin
                                err = del_error_in ;
                                ack = ~del_error_in ;
                            end
                            else
                            begin
                                ack = ~ccyc_hit ;
                                conf_wenable = ~ccyc_hit ;
                            end
                            `else
                            ack = 1'b1 ;
                            conf_wenable = 1'b1 ;
                            `endif
                        end
                    end // S_CONF_WRITE

    S_CONF_READ:   begin
                        `ifdef HOST
                            wbw_data_out_sel = SEL_CCYC_ADDR ;
                            del_req          = ~burst_transfer && ( do_ccyc_req  || do_iack_req  ) ;
                            del_done         = ~burst_transfer && ( do_ccyc_comp || do_iack_comp ) ;
                            del_in_progress  = ~burst_transfer && ( do_ccyc_comp || do_iack_comp ) ;
                            wbr_fifo_renable = ~burst_transfer && ( do_ccyc_comp || do_iack_comp ) ;
                        `endif

                        n_state = S_IDLE ; // next state after configuration access is always idle

                        if ( burst_transfer )
                        begin
                            err = 1'b1 ;
                        end
                        else
                        begin
                            `ifdef HOST
                            if ( do_ccyc_req || ( ccyc_hit && ~do_ccyc_comp ))
                            begin
                                rty = 1'b1 ;
                            end
                            else
                            if ( do_iack_req || ( iack_hit && ~do_iack_comp ))
                            begin
                                rty = 1'b1 ;
                            end
                            else
                            if ( do_iack_comp || do_ccyc_comp )
                            begin
                                err = del_error_in ;
                                ack = ~del_error_in ;
                            end
                            else
                            begin
                                ack = ~( ccyc_hit || iack_hit ) ;
                                conf_renable = ~( ccyc_hit || iack_hit ) ;
                            end
                            `else
                            ack = 1'b1 ;
                            conf_renable = 1'b1 ;
                            `endif
                        end
                    end //S_CONF_READ
    default:begin
                n_state = S_IDLE ; // return to idle state
            end //default
    endcase
end

// configuration space offset output assignment
assign wb_conf_offset_out = {wb_addr_in[11:2], 2'b00} ; // upper 10 bits of address input and two zeros

// data output assignment - for image writes, first data is address, subsequent data comes from intermediate register
reg [31:0] wb_data ;
`ifdef HOST
reg [1:0] wbw_data_out_sel_reg ;
always@(posedge wb_clock_in or posedge reset_in)
begin
    if ( reset_in )
        wbw_data_out_sel_reg <= #`FF_DELAY SEL_ADDR_IN ;
    else
        wbw_data_out_sel_reg <= #`FF_DELAY wbw_data_out_sel ;
end

always@(wbw_data_out_sel_reg or wb_addr_in or ccyc_addr_in or d_incoming)
begin
    case ( wbw_data_out_sel_reg )
        SEL_CCYC_ADDR:  wb_data = ccyc_addr_in ;
        SEL_DATA_IN:    wb_data = d_incoming ;
        default: wb_data        = wb_addr_in ;
    endcase
end
`else
`ifdef GUEST
reg wbw_data_out_sel_reg ;
always@(posedge wb_clock_in or posedge reset_in)
begin
    if ( reset_in )
        wbw_data_out_sel_reg <= #`FF_DELAY SEL_ADDR_IN ;
    else
        wbw_data_out_sel_reg <= #`FF_DELAY wbw_data_out_sel ;
end

always@(wbw_data_out_sel_reg or wb_addr_in or d_incoming)
begin
    if ( wbw_data_out_sel_reg )
        wb_data = wb_addr_in ;
    else
        wb_data = d_incoming ;
end
`endif
`endif

// command / byte enable assignment - with address, bus command is provided, with data - byte enables are provided
reg [3:0] wb_cbe ;

always@(wbw_data_out_sel_reg or d_incoming or map)
begin
    if (wbw_data_out_sel_reg && map)
        wb_cbe = `BC_IO_WRITE ;
    else
    if (wbw_data_out_sel_reg)
        wb_cbe = `BC_MEM_WRITE ;
    else
        wb_cbe = ~(d_incoming[35:32]) ;
end

// for configuration writes, data output is always data from WISHBONE - in guest implementation data is all 0.
`ifdef GUEST
    assign wb_conf_data_out = 32'h00000000 ;
`endif

`ifdef GUEST
    `ifdef NO_CNF_IMAGE
    `else
        `define PCI_WB_SLAVE_DO_OUT_MUX
    `endif
`else
`ifdef HOST
    `define PCI_WB_SLAVE_DO_OUT_MUX ;
`endif
`endif

`ifdef PCI_WB_SLAVE_DO_OUT_MUX
    reg [31:0] sdata_source ;

    // WISHBONE data output select lines for output multiplexor
    wire sdata_o_sel_new = ( wb_conf_hit_in && ~wiack_hit && ~wccyc_hit ) ? CONF_SEL : WBR_SEL ;
    reg sdata_o_sel ;

    always@(posedge wb_clock_in or posedge reset_in)
    begin
        if ( reset_in )
            sdata_o_sel <= #`FF_DELAY WBR_SEL ;
        else
        if ( decode_en )
            sdata_o_sel <= #`FF_DELAY sdata_o_sel_new ;
    end

    always@(sdata_o_sel or wbr_fifo_data_in or wb_conf_data_in)
    begin
        case (sdata_o_sel)
            WBR_SEL :sdata_source = wbr_fifo_data_in ;
            CONF_SEL:sdata_source = wb_conf_data_in ;
        endcase
    end
`else
    wire [31:0] sdata_source = wbr_fifo_data_in ;
`endif

`ifdef REGISTER_WBS_OUTPUTS

always@(posedge wb_clock_in or posedge reset_in)
begin
    if ( reset_in )
    begin
        ACK_O         <= #`FF_DELAY 1'b0 ;
        RTY_O         <= #`FF_DELAY 1'b0 ;
        ERR_O         <= #`FF_DELAY 1'b0 ;
        SDATA_O       <= #`FF_DELAY 0 ;
        del_write_out <= #`FF_DELAY 1'b0 ;

        `ifdef HOST
        wb_conf_wenable_out <= #`FF_DELAY 1'b0 ;
        wb_conf_data_out    <= #`FF_DELAY 0 ;
        `endif

        del_bc_out    <= #`FF_DELAY `BC_RESERVED0 ;
        del_req_out <= #`FF_DELAY 1'b0 ;
        del_done_out <= #`FF_DELAY 1'b0 ;
        del_burst_out <= #`FF_DELAY 1'b0 ;
        del_in_progress_out <= #`FF_DELAY 1'b0 ;
        wb_conf_be_out <= #`FF_DELAY 0 ;
        wb_data_out    <= #`FF_DELAY 0 ;
        wb_cbe_out <= #`FF_DELAY 0 ;
        wbw_fifo_wenable_out <= #`FF_DELAY 0 ;
        wbw_fifo_control_out <= #`FF_DELAY 0 ;
        wbr_fifo_renable_out <= #`FF_DELAY 0 ;
    end
    else
    begin
        ACK_O   <= #`FF_DELAY ack && !ACK_O ;
        RTY_O   <= #`FF_DELAY rty && !RTY_O ;
        ERR_O    <= #`FF_DELAY err && !ERR_O ;
        SDATA_O       <= #`FF_DELAY sdata_source ;
        del_write_out <= #`FF_DELAY WE_I ;

        `ifdef HOST
        wb_conf_wenable_out <= #`FF_DELAY conf_wenable ;
        wb_conf_data_out    <= #`FF_DELAY SDATA_I ;
        `endif

        del_bc_out <= #`FF_DELAY del_bc ;
        del_req_out <= #`FF_DELAY del_req ;
        del_done_out <= #`FF_DELAY del_done ;
        del_burst_out <= #`FF_DELAY del_burst ;
        del_in_progress_out <= #`FF_DELAY del_in_progress ;
        wb_conf_be_out <= #`FF_DELAY SEL_I ;
        wb_data_out <= #`FF_DELAY wb_data ;
        wb_cbe_out <= #`FF_DELAY wb_cbe ;
        wbw_fifo_wenable_out <= #`FF_DELAY wbw_fifo_wenable ;
        wbw_fifo_control_out <= #`FF_DELAY wbw_fifo_control ;
        wbr_fifo_renable_out <= #`FF_DELAY wbr_fifo_renable ;
    end
end

`else

assign SDATA_O = sdata_source ;

assign ACK_O = ack ;
assign RTY_O = rty ;
assign ERR_O = err ;

// write operation indicator for delayed transaction requests
assign del_write_out = WE_I ;
assign del_bc_out = del_bc ;
assign del_req_out  = del_req ; // read request
assign del_done_out = del_done ; // read done
assign del_burst_out = del_burst ;
assign del_in_progress_out = del_in_progress ;
`ifdef HOST
assign wb_conf_data_out = SDATA_I ;
assign wb_conf_wenable_out = conf_wenable ;
`endif
// Configuration space byte enables output
assign wb_conf_be_out = SEL_I ; // just route select lines from WISHBONE to conf space
assign wb_data_out    = wb_data ;
assign wb_cbe_out = wb_cbe ;
assign wbw_fifo_wenable_out = wbw_fifo_wenable ; //write enable for WBW_FIFO
assign wbw_fifo_control_out = wbw_fifo_control ; //control bus output for WBW_FIFO
assign wbr_fifo_renable_out = wbr_fifo_renable ; //read enable for wbr_fifo
`endif

endmodule //WB_SLAVE