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[raggedstone] / heartbeat / source / pciwbsequ.v

// Copyright (C) 2005 Peio Azkarate, peio@opencores.org
//
//   This source file is free software; you can redistribute it
//   and/or modify it under the terms of the GNU Lesser General
//   Public License as published by the Free Software Foundation;
//   either version 2.1 of the License, or (at your option) any
//   later version.
//

(* signal_encoding = "user" *)
(* safe_implementation = "yes" *)

module pciwbsequ_new ( clk_i, nrst_i, cmd_i, cbe_i, frame_i, irdy_i, devsel_o, 
        trdy_o, adrcfg_i, adrmem_i, pciadrLD_o, pcidOE_o, parOE_o, wbdatLD_o, 
        wbrgdMX_o, wbd16MX_o, wrcfg_o, rdcfg_o, wb_sel_o, wb_we_o, wb_stb_o, 
        wb_cyc_o, wb_ack_i, wb_err_i, debug_init, debug_access );

        // General 
        input clk_i;
        input nrst_i;
        // pci 
        // adr_i
        input [3:0] cmd_i;
        input [3:0] cbe_i;
        input frame_i;
        input irdy_i;
        output devsel_o;
        output trdy_o;
        // control
        input adrcfg_i;
        input adrmem_i;
        output pciadrLD_o;
        output pcidOE_o;
        output reg parOE_o;
        output wbdatLD_o;
        output wbrgdMX_o;
        output wbd16MX_o;
        output wrcfg_o;
        output rdcfg_o;
        // whisbone
        output [1:0] wb_sel_o;
        output wb_we_o;
        inout wb_stb_o;
        output wb_cyc_o;
        input wb_ack_i;
        input wb_err_i;
        // debug signals
        output reg debug_init;
        output reg debug_access;

        //type PciFSM is ( PCIIDLE, B_BUSY, S_DATA1, S_DATA2, TURN_AR );        
        //wire pst_pci          : PciFSM;
        //wire nxt_pci          : PciFSM;

        //      typedef enum reg [2:0] {
        //              RED, GREEN, BLUE, CYAN, MAGENTA, YELLOW
        //      } color_t;
        //
        //      color_t   my_color = GREEN;

        // parameter PCIIDLE    = 2'b00;
        // parameter B_BUSY     = 2'b01;
        // parameter S_DATA1    = 2'b10;
        // parameter S_DATA2    = 2'b11;
        // parameter TURN_AR    = 3'b100;

        reg [2:0] pst_pci;
        reg [2:0] nxt_pci;

        parameter [2:0] 
                PCIIDLE    = 3'b000,
                B_BUSY     = 3'b001,
                S_DATA1    = 3'b010,
                S_DATA2    = 3'b011,
                TURN_AR    = 3'b100;


        initial begin
                pst_pci = 3'b000;
        end

        initial begin
                nxt_pci = 3'b000;
        end
        
        wire sdata1;
        wire sdata2;
        wire idleNX;
        wire sdata1NX;
        wire sdata2NX;
        wire turnarNX;
        wire idle;
        reg  devselNX_n;
        reg  trdyNX_n;
        reg  devsel;
        reg  trdy;
        wire adrpci;
        wire acking;
        wire rdcfg;
        reg  targOE;
        reg  pcidOE;

        // always @(nrst_i or clk_i or nxt_pci)
        always @(negedge nrst_i or posedge clk_i)
        begin
        if( nrst_i == 0 )
                        pst_pci <= PCIIDLE;
                else 
                        pst_pci <= nxt_pci; 
        end

        // always @(negedge nrst_i or posedge clk_i)
        always @( pst_pci or frame_i or irdy_i or adrcfg_i or adrpci or acking )
        begin
                devselNX_n      <= 1'b1;
                trdyNX_n        <= 1'b1;        
                case (pst_pci)
            PCIIDLE : 
                        begin
                                if ( frame_i == 0 )
                                        nxt_pci <= B_BUSY;      
                                else
                                        nxt_pci <= PCIIDLE;
                        end
                B_BUSY:
                                if ( adrpci == 0 )
                                        nxt_pci <= TURN_AR;
                                else
                                        begin
                                        nxt_pci <= S_DATA1;
                                        devselNX_n <= 0; 
                                        end
                        S_DATA1:
                                if ( acking == 1 )
                                        begin
                                        nxt_pci         <= S_DATA2;
                                        devselNX_n      <= 0;                                   
                                        trdyNX_n        <= 0;   
                                        end
                                else
                                        begin
                                        nxt_pci <= S_DATA1;
                                        devselNX_n <= 0;                                        
                                        end
                        S_DATA2:
                        if ( frame_i == 1 && irdy_i == 0 )
                                        nxt_pci <= TURN_AR;
                                else
                                        begin
                                        nxt_pci <= S_DATA2;
                                        devselNX_n <= 0;
                                        trdyNX_n <= 0;
                                        end
                        TURN_AR:
                                if ( frame_i == 1 )
                                        nxt_pci <= PCIIDLE;
                                else
                                        nxt_pci <= TURN_AR;
            endcase
        end

        // FSM control signals
        assign adrpci = adrmem_i;
        
        assign acking = (
                ( wb_ack_i == 1 || wb_err_i == 1 ) || 
                ( adrcfg_i == 1 &&   irdy_i == 0)
        ) ? 1'b1 : 1'b0; 

        // FSM derived Control signals
        assign idle             = ( pst_pci <= PCIIDLE ) ? 1'b1 : 1'b0;
        assign sdata1           = ( pst_pci <= S_DATA1 ) ? 1'b1 : 1'b0;
        assign sdata2           = ( pst_pci <= S_DATA2 ) ? 1'b1 : 1'b0;
        assign idleNX           = ( nxt_pci <= PCIIDLE ) ? 1'b1 : 1'b0;
        assign sdata1NX         = ( nxt_pci <= S_DATA1 ) ? 1'b1 : 1'b0;
        assign sdata2NX         = ( nxt_pci <= S_DATA2 ) ? 1'b1 : 1'b0;
        assign turnarNX         = ( nxt_pci <= TURN_AR ) ? 1'b1 : 1'b0;

        // PCI Data Output Enable
        // always @( nrst_i or clk_i or cmd_i [0] or sdata1NX or turnarNX )
        always @(negedge nrst_i or posedge clk_i)
        begin
        if ( nrst_i == 0 )
                        pcidOE <= 0;
                else
                        if ( sdata1NX == 1 && cmd_i [0] == 0 )
                                pcidOE <= 1;
                        else 
                                if ( turnarNX == 1 )
                                        pcidOE <= 0;
        end

        assign pcidOE_o = pcidOE;

        // PAR Output Enable
        // PCI Read data phase
        // PAR is valid 1 cicle after data is valid
        // always @( nrst_i or clk_i or cmd_i [0] or sdata2NX or turnarNX )
        always @(negedge nrst_i or posedge clk_i)
        begin
        if ( nrst_i == 0 )
                        parOE_o <= 0;
                else
                        if ( ( sdata2NX == 1 || turnarNX == 1 ) && cmd_i [0] == 0 )
                                parOE_o <= 1;
                        else
                                parOE_o <= 0;
        end

        // Target s/t/s signals OE control
        // targOE <= '1' when ( idle = '0' and adrpci = '1' ) else '0';
        // always @( nrst_i or clk_i or sdata1NX or idleNX )
        always @(negedge nrst_i or posedge clk_i)
        begin
        if ( nrst_i == 0 )
                        targOE <= 0;
                else
                        if ( sdata1NX == 1 )
                                targOE <= 1;
                        else 
                                if ( idleNX == 1 )
                                        targOE <= 0;
        end
                
    // WHISBONE outs
        assign wb_cyc_o = (adrmem_i == 1 && sdata1 == 1) ? 1'b1 : 1'b0;
    assign wb_stb_o = (adrmem_i == 1 && sdata1 == 1 && irdy_i == 0 ) ? 1'b1 : 1'b0;

        // PCI(Little endian) to WB(Big endian)
        assign wb_sel_o [1] = (! cbe_i [0]) || (! cbe_i [2]);
        assign wb_sel_o [0] = (! cbe_i [1]) || (! cbe_i [3]);   

        assign wb_we_o = cmd_i [0];

        // Syncronized PCI outs
        always @(negedge nrst_i or posedge clk_i)
        begin
                if( nrst_i == 0 )
                        begin
                        devsel  <= 1;
                        trdy    <= 1;
                        end
                else
                        begin
                        devsel <= devselNX_n;
                        trdy   <= trdyNX_n;
                        end
        end

        assign devsel_o = ( targOE == 1 ) ? devsel : 1'bZ;
        assign trdy_o   = ( targOE == 1 ) ? trdy   : 1'bZ;

        // rd/wr Configuration Space Registers
        assign wrcfg_o = (
                adrcfg_i == 1 &&
                cmd_i [0] == 1 &&
                sdata2 == 1
        ) ? 1'b1 : 1'b0;

        assign rdcfg = (
                adrcfg_i == 1 &&
                cmd_i [0] == 0 &&
                (sdata1 == 1 || sdata2 == 1)
        ) ? 1'b1 : 1'b0;

        assign rdcfg_o = rdcfg;

        // LoaD enable signals
        assign pciadrLD_o = ! frame_i;
        assign wbdatLD_o  = wb_ack_i;

        // Mux control signals
        assign wbrgdMX_o = ! rdcfg;
        assign wbd16MX_o = (cbe_i [3] == 0 || cbe_i [2] == 0) ? 1'b1 : 1'b0;
        
        // debug outs 
        always @(negedge nrst_i or posedge clk_i)
        begin
                if ( nrst_i == 0 )
                        debug_init <= 0;
                else
                        if (devsel == 0)
                                debug_init <= 1;
        end

        always @(negedge nrst_i or posedge clk_i)
        begin
                if ( nrst_i == 0 )
                        debug_access <= 0;
                else
                        if (wb_stb_o == 1)
                                debug_access <= 1;
        end

endmodule