pci_wb_master.v

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

                    n_state = S_WRITE_ERR_RTY ; // go here to clean this write transaction from PCIW_FIFO
            end
            3'b001 : // If writting of one data is retried
            begin
                addr_count = 1'b0 ;
                last_data_transferred = 1'b0 ;
                retried_d = 1'b1 ; // there was a retry
                wait_for_wb_response = 1'b0 ;
                if(rty_counter_almost_max_value) // If retry counter reached maximum allowed value
                begin
                    if (last_data_from_pciw_fifo_reg) // if last data was transfered
                        pciw_fifo_renable = 1'b0 ;
                    else // if there wasn't last data of transfere
                        pciw_fifo_renable = 1'b1 ;
                    n_state = S_WRITE_ERR_RTY ; // go here to clean this write transaction from PCIW_FIFO
                    write_rty_cnt_exp_out = 1'b1 ; // signal for reporting write counter expired
                    pci_error_sig_out = 1'b1 ;
                    error_source_out = 1'b1 ; // error ocuerd because of retry counter
                end
                else
                begin
                    pciw_fifo_renable = 1'b0 ;
                    n_state = S_IDLE ; // go to S_IDLE state for retrying the transaction
                    write_rty_cnt_exp_out = 1'b0 ; // retry counter hasn't expired yet
                    pci_error_sig_out = 1'b0 ;
                    error_source_out = 1'b0 ;
                end
            end
            default :
            begin
                addr_count = 1'b0 ;
                last_data_transferred = 1'b0 ;
                wait_for_wb_response = 1'b1 ; // wait for WB device to response (after 8 clocks RTY CNT is incremented)
                error_source_out = 1'b0 ; // if error ocures, error source is from other WB bus side
                if((rty_counter_almost_max_value)&&(set_retry)) // when no WB response and RTY CNT reached maximum allowed value 
                begin
                    retried_d = 1'b1 ;
                    if (last_data_from_pciw_fifo_reg) // if last data was transfered
                        pciw_fifo_renable = 1'b0 ;
                    else // if there wasn't last data of transfere
                        pciw_fifo_renable = 1'b1 ;
                    n_state = S_WRITE_ERR_RTY ; // go here to clean this write transaction from PCIW_FIFO
                    write_rty_cnt_exp_out = 1'b1 ; // signal for reporting write counter expired
                    pci_error_sig_out = 1'b1 ; // signal for error reporting
                end
                else
                begin
               	    pciw_fifo_renable = 1'b0 ;
                    retried_d = 1'b0 ;
                    n_state = S_WRITE ; // stay in S_WRITE state to wait WB to response
                    write_rty_cnt_exp_out = 1'b0 ; // retry counter hasn't expired yet
                    pci_error_sig_out = 1'b0 ;
                end
            end
            endcase
        end
    S_WRITE_ERR_RTY: // Clean current write transaction from PCIW_FIFO if ERROR or Retry counter expired occures
        begin
            pciw_fifo_renable = !last_data_from_pciw_fifo_reg ; // put out next data (untill last data or FIFO empty)
            last_data_transferred = 1'b1 ; // after exiting this state, negedge of this signal is used
            // Default values for signals not used in this state
            pcir_fifo_wenable = 1'b0 ;
            pcir_fifo_control = 4'h0 ;
            addr_into_cnt = 1'b0 ;
            read_count_load = 1'b0 ;
            read_count_enable = 1'b0 ;
            addr_count = 1'b0 ;
            pci_error_sig_out = 1'b0 ;
            error_source_out = 1'b0 ;
            retried_d = 1'b0 ;
            wb_read_done = 1'b0 ;
            write_rty_cnt_exp_out = 1'b0 ;
            read_rty_cnt_exp_out = 1'b0 ;
            wait_for_wb_response = 1'b0 ;
            // If last data is cleaned out from PCIW_FIFO
            if (last_data_from_pciw_fifo_reg)
                n_state = S_IDLE ;
            else
                n_state = S_WRITE_ERR_RTY ; // Clean until last data is cleaned out from FIFO
        end
    S_READ: // READ from WB bus to PCIR_FIFO
        begin
            // Default values for signals not used in this state
            pciw_fifo_renable = 1'b0 ;
            addr_into_cnt = 1'b0 ;
            read_count_load = 1'b0 ;
            pci_error_sig_out = 1'b0 ;
            error_source_out = 1'b0 ;
            write_rty_cnt_exp_out = 1'b0 ;
            case ({wb_ack_i, wb_err_i, wb_rty_i})
            3'b100 : // If reading of one data is acknowledged
            begin
                pcir_fifo_wenable = 1'b1 ; // enable writting data into PCIR_FIFO
                addr_count = 1'b1 ; // prepare next address if there will be burst
                read_count_enable = 1'b1 ; // decrease counter value for cache line size
                retried_d = 1'b0 ; // there was no retry
                read_rty_cnt_exp_out = 1'b0 ; // there was no retry
                wait_for_wb_response = 1'b0 ;
                // if last data was transfered
                if (last_data_to_pcir_fifo)
                begin
                    pcir_fifo_control[`LAST_CTRL_BIT]       = 1'b1 ; // FIFO must indicate LAST data transfered
                    pcir_fifo_control[`DATA_ERROR_CTRL_BIT] = 1'b0 ;
                    pcir_fifo_control[`UNUSED_CTRL_BIT]     = 1'b0 ;
                    pcir_fifo_control[`ADDR_CTRL_BIT]       = 1'b0 ;
                    last_data_transferred = 1'b1 ; // signal for last data transfered
                    wb_read_done = 1'b1 ; // signal last data of read transaction for PCI Target
                    n_state = S_TURN_ARROUND ;
                end
                else // if not last data transfered
                begin
                    pcir_fifo_control = 4'h0 ; // ZERO for control code
                    last_data_transferred = 1'b0 ; // not last data transfered
                    wb_read_done = 1'b0 ; // read is not done yet
                    n_state = S_READ ;
                end
            end
            3'b010 : // If reading of one data is terminated with ERROR
            begin
                pcir_fifo_wenable = 1'b1 ; // enable for writting to FIFO data with ERROR
                addr_count = 1'b0 ; // no need for new address
                pcir_fifo_control[`LAST_CTRL_BIT]       = 1'b0 ;
                pcir_fifo_control[`DATA_ERROR_CTRL_BIT] = 1'b1 ; // FIFO must indicate the DATA with ERROR
                pcir_fifo_control[`UNUSED_CTRL_BIT]     = 1'b0 ;
                pcir_fifo_control[`ADDR_CTRL_BIT]       = 1'b0 ;
                last_data_transferred = 1'b1 ; // signal for last data transfered
                wb_read_done = 1'b1 ; // signal last data of read transaction for PCI Target
                read_count_enable = 1'b0 ; // no need for cache line, when error occures
                n_state = S_TURN_ARROUND ;
                retried_d = 1'b0 ; // there was no retry
                wait_for_wb_response = 1'b0 ;
                read_rty_cnt_exp_out = 1'b0 ; // there was no retry
            end
            3'b001 : // If reading of one data is retried
            begin
                pcir_fifo_wenable = 1'b0 ;
                pcir_fifo_control = 4'h0 ;
                addr_count = 1'b0 ;
                read_count_enable = 1'b0 ;
                wait_for_wb_response = 1'b0 ;
                case ({first_wb_data_access, rty_counter_almost_max_value})
                2'b10 :
                begin  // if first data of the cycle (CYC_O) is retried - after each retry CYC_O goes inactive 
                    n_state = S_IDLE ; // go to S_IDLE state for retrying the transaction
                    read_rty_cnt_exp_out = 1'b0 ; // retry counter hasn't expired yet   
                    last_data_transferred = 1'b0 ;
                    wb_read_done = 1'b0 ;
                    retried_d = 1'b1 ; // there was a retry
                end
                2'b11 :
                begin  // if retry counter reached maximum value
                    n_state = S_READ_RTY ; // go here to wait for PCI Target to remove read request
                    read_rty_cnt_exp_out = 1'b1 ; // signal for reporting read counter expired  
                    last_data_transferred = 1'b0 ;
                    wb_read_done = 1'b0 ;
                    retried_d = 1'b1 ; // there was a retry
                end
                default : // if retry occures after at least 1 data was transferred without breaking cycle (CYC_O inactive)
                begin     // then PCI device will retry access!
                    n_state = S_TURN_ARROUND ; // go to S_TURN_ARROUND state 
                    read_rty_cnt_exp_out = 1'b0 ; // retry counter hasn't expired  
                    last_data_transferred = 1'b1 ;
                    wb_read_done = 1'b1 ;
                    retried_d = 1'b0 ; // retry must not be retried, since there is not a first data
                end
                endcase
            end
            default :
            begin
                addr_count = 1'b0 ;
                read_count_enable = 1'b0 ;
                read_rty_cnt_exp_out = 1'b0 ;
                wait_for_wb_response = 1'b1 ; // wait for WB device to response (after 8 clocks RTY CNT is incremented)
                if((rty_counter_almost_max_value)&&(set_retry)) // when no WB response and RTY CNT reached maximum allowed value 
                begin
                    retried_d = 1'b1 ;
                    n_state = S_TURN_ARROUND ; // go here to stop read request
                    pcir_fifo_wenable = 1'b1 ;
                    pcir_fifo_control[`LAST_CTRL_BIT]       = 1'b0 ;
                    pcir_fifo_control[`DATA_ERROR_CTRL_BIT] = 1'b1 ; // FIFO must indicate the DATA with ERROR
                    pcir_fifo_control[`UNUSED_CTRL_BIT]     = 1'b0 ;
                    pcir_fifo_control[`ADDR_CTRL_BIT]       = 1'b0 ;
                    last_data_transferred = 1'b1 ;
                    wb_read_done = 1'b1 ;
                end
                else
                begin
                    retried_d = 1'b0 ;
                    n_state = S_READ ; // stay in S_READ state to wait WB to response
                    pcir_fifo_wenable = 1'b0 ;
                    pcir_fifo_control = 4'h0 ;
                    last_data_transferred = 1'b0 ;
                    wb_read_done = 1'b0 ;
                end
            end
            endcase
        end
    S_READ_RTY: // Wait for PCI Target to remove read request, when retry counter reaches maximum value!
        begin
            // Default values for signals not used in this state
            pciw_fifo_renable = 1'b0 ;
            pcir_fifo_wenable = 1'b0 ;
            pcir_fifo_control = 4'h0 ;
            addr_into_cnt = 1'b0 ;
            read_count_load = 1'b0 ;
            read_count_enable = 1'b0 ;
            addr_count = 1'b0 ;
            pci_error_sig_out = 1'b0 ;
            error_source_out = 1'b0 ;
            retried_d = 1'b0 ;
            wb_read_done = 1'b0 ;
            write_rty_cnt_exp_out = 1'b0 ;
            read_rty_cnt_exp_out = 1'b0 ;
            wait_for_wb_response = 1'b0 ;
            // wait for PCI Target to remove read request
            if (pci_tar_read_request)
            begin
                n_state = S_READ_RTY ; // stay in this state until read request is removed
                last_data_transferred = 1'b0 ;
            end
            else // when read request is removed
            begin
                n_state = S_IDLE ;
                last_data_transferred = 1'b1 ; // when read request is removed, there is "last" data
            end
        end    
    // Turn arround cycle after writting to PCIR_FIFO (for correct data when reading from PCIW_FIFO)  
    default: // S_TURN_ARROUND: 
        begin
            // Default values for signals not used in this state
            pciw_fifo_renable = 1'b0 ;
            pcir_fifo_wenable = 1'b0 ;
            pcir_fifo_control = 4'h0 ;
            addr_into_cnt = 1'b0 ;
            read_count_load = 1'b0 ;
            read_count_enable = 1'b0 ;
            addr_count = 1'b0 ;
            pci_error_sig_out = 1'b0 ;
            error_source_out = 1'b0 ;
            retried_d = 1'b0 ;
            last_data_transferred = 1'b1 ;
            wb_read_done = 1'b0 ;
            write_rty_cnt_exp_out = 1'b0 ;
            read_rty_cnt_exp_out = 1'b0 ;
            wait_for_wb_response = 1'b0 ;
            n_state = S_IDLE ;
        end     
    endcase
end

// Signal for retry monitor in state machine when there is read and first (or single) data access
wire ack_rty_response = wb_ack_i || wb_rty_i ;

// Signal first_wb_data_access is set when no WB cycle present till end of first data access of WB cycle on WB bus
always@(posedge wb_clock_in or posedge reset_in)
begin
    if (reset_in)
        first_wb_data_access = 1'b1 ;
    else
    begin
        if (~wb_cyc_o)
            first_wb_data_access = 1'b1 ;
        else if (ack_rty_response)
            first_wb_data_access = 1'b0 ;
    end
end

// Signals to FIFO
assign  pcir_fifo_be_out = 4'hf ; // pci_tar_be ;

// Signals to Conf. space
assign  pci_error_bc = bc_register ;


always@(posedge wb_clock_in or posedge reset_in)
begin
    if (reset_in)
        wb_read_done_out <= #`FF_DELAY 1'b0 ;
    else
        wb_read_done_out <= #`FF_DELAY wb_read_done ;
end

always@(pciw_fifo_renable or addr_into_cnt_reg or pciw_fifo_control_in or pciw_fifo_empty_in)
begin
    pciw_fifo_renable_out           = pciw_fifo_renable || addr_into_cnt_reg ;
    last_data_from_pciw_fifo_reg    = pciw_fifo_control_in[`ADDR_CTRL_BIT] || pciw_fifo_empty_in ;
end


endmodule