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//////////////////////////////////////////////////////////////////////

////                                                              ////

////  MP3 demo Flash interface                                    ////

////                                                              ////

////  This file is part of the MP3 demo application               ////

////  http://www.opencores.org/cores/or1k/mp3/                    ////

////                                                              ////

////  Description                                                 ////

////  Connects MP3 demo tp Flash found on XSV board.              ////

////                                                              ////

////  To Do:                                                      ////

////   - nothing really                                           ////

////                                                              ////

////  Author(s):                                                  ////

////      - Lior Shtram, lior.shtram@flextronicssemi.com          ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

////                                                              ////

//// Copyright (C) 2001 Authors                                   ////

////                                                              ////

//// This source file may be used and distributed without         ////

//// restriction provided that this copyright statement is not    ////

//// removed from the file and that any derivative work contains  ////

//// the original copyright notice and the associated disclaimer. ////

////                                                              ////

//// 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.                                               ////

////                                                              ////

//// This source is distributed in the hope that it will be       ////

//// useful, but WITHOUT ANY WARRANTY; without even the implied   ////

//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR      ////

//// PURPOSE.  See the GNU Lesser General Public License for more ////

//// details.                                                     ////

////                                                              ////

//// You should have received a copy of the GNU Lesser General    ////

//// Public License along with this source; if not, download it   ////

//// from http://www.opencores.org/lgpl.shtml                     ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

//

// CVS Revision History

//

// $Log: not supported by cvs2svn $

// Revision 1.3  2002/01/23 07:50:44  lampret

// Added wb_err_o to flash and sram i/f for testing the buserr exception.

//

// Revision 1.2  2002/01/14 06:18:22  lampret

// Fixed mem2reg bug in FAST implementation. Updated debug unit to work with new genpc/if.

//

// Revision 1.1.1.1  2001/11/04 19:00:09  lampret

// First import.

//

//

// synopsys translate_off

`include "timescale.v"

// synopsys translate_on

`include "bench_define.v"

`ifdef FLASH_GENERIC

module flash_top (

  clk, rstn,

  wb_dat_i, wb_dat_o, wb_adr_i, wb_sel_i, wb_we_i, wb_cyc_i,

  wb_stb_i, wb_ack_o, wb_err_o,

  flash_rstn, cen, oen, wen, rdy, d, a, a_oe

);

input   clk;

input   rstn;

input [31:0]  wb_dat_i;

output [31:0] wb_dat_o;

input [31:0]  wb_adr_i;

input [3:0] wb_sel_i;

input   wb_we_i;

input   wb_cyc_i;

input   wb_stb_i;

output    wb_ack_o;

output    wb_err_o;

output    flash_rstn;

output    oen;

output    cen;

output    wen;

input   rdy;

inout [7:0] d;

output [20:0] a;

output  a_oe;

reg [7:0] mem [65535:0];

wire [31:0] adr;

`ifdef FLASH_GENERIC_REGISTERED

reg             wb_ack_o;

reg             wb_err_o;

reg     [31:0]   wb_dat_o;

`endif

wire            wb_err;

assign flash_rstn = 1'b1;

assign oen = 1'b1;

assign cen = 1'b1;

assign wen = 1'b1;

assign a = 21'b0;

assign a_oe = 1'b1;

initial $readmemh("../src/flash.in", mem, 0);

assign adr = {wb_adr_i[31:2], 2'b00};

`ifdef FLASH_GENERIC_REGISTERED

always @(negedge rstn or posedge clk)

        if (!rstn)

                wb_dat_o <= #1 32'h0000_0000;

        else begin

                wb_dat_o[7:0] <= #1 wb_adr_i < 65535 ? mem[adr+3] : 8'h00;

                wb_dat_o[15:8] <= #1 wb_adr_i < 65535 ? mem[adr+2] : 8'h00;

                wb_dat_o[23:16] <= #1 wb_adr_i < 65535 ? mem[adr+1] : 8'h00;

                wb_dat_o[31:24] <= #1 wb_adr_i < 65535 ? mem[adr+0] : 8'h00;

        end

`else

assign wb_dat_o[7:0] = wb_adr_i < 65535 ? mem[adr+3] : 8'h00;

assign wb_dat_o[15:8] = wb_adr_i < 65535 ? mem[adr+2] : 8'h00;

assign wb_dat_o[23:16] = wb_adr_i < 65535 ? mem[adr+1] : 8'h00;

assign wb_dat_o[31:24] = wb_adr_i < 65535 ? mem[adr+0] : 8'h00;

`endif

`ifdef FLASH_GENERIC_REGISTERED

always @(posedge clk or negedge rstn)

        if (!rstn)

                wb_ack_o <= #1 1'b0;

        else

                wb_ack_o <= #1 wb_cyc_i & wb_stb_i & !wb_ack_o;

`else

assign wb_ack_o = wb_cyc_i & wb_stb_i;

`endif

assign wb_err = wb_cyc_i & wb_stb_i & (|wb_adr_i[27:21]);     // If Access to > 2MB (4-bit leading prefix ignored)

`ifdef FLASH_GENERIC_REGISTERED

always @(posedge clk or negedge rstn)

        if (!rstn)

                wb_err_o <= #1 1'b0;

        else

                wb_err_o <= #1 wb_err & !wb_err_o;

`else

assign wb_err_o = wb_err;

`endif

// synopsys translate_off

integer fflash;

initial fflash = $fopen("flash.log");

always @(posedge clk)

        if (wb_cyc_i)

                if (wb_stb_i & wb_we_i) begin

//                      $fdisplay(fflash, "%t Trying to write into flash at %h (%b)", $time, wb_adr_i, wb_we_i);

//                      #100 $finish;

                        if (wb_sel_i[3])

                                mem[{wb_adr_i[31:2], 2'b00}+0] = wb_dat_i[31:24];

                        if (wb_sel_i[2])

                                mem[{wb_adr_i[31:2], 2'b00}+1] = wb_dat_i[23:16];

                        if (wb_sel_i[1])

                                mem[{wb_adr_i[31:2], 2'b00}+2] = wb_dat_i[15:8];

                        if (wb_sel_i[0])

                                mem[{wb_adr_i[31:2], 2'b00}+3] = wb_dat_i[7:0];

                        $fdisplay(fflash, "%t [%h] <- write %h, byte sel %b", $time, wb_adr_i, wb_dat_i, wb_sel_i);

                end else if (wb_ack_o)

                        $fdisplay(fflash, "%t [%h] -> read %h", $time, wb_adr_i, wb_dat_o);

// synopsys translate_on

endmodule

`else

module flash_top (

  clk, rstn,

  wb_dat_i, wb_dat_o, wb_adr_i, wb_sel_i, wb_we_i, wb_cyc_i,

  wb_stb_i, wb_ack_o, wb_err_o,

  flash_rstn, cen, oen, wen, rdy, d, a, a_oe

);

input   clk;

input   rstn;

input [31:0]  wb_dat_i;

output [31:0] wb_dat_o;

input [31:0]  wb_adr_i;

input [3:0] wb_sel_i;

input   wb_we_i;

input   wb_cyc_i;

input   wb_stb_i;

output    wb_ack_o;

output    wb_err_o;

output    flash_rstn;

output    oen;

output    cen;

output    wen;

input   rdy;

inout [7:0] d;

output [20:0] a;

output  a_oe;

reg [4:0] counter;

reg [31:0]  data_sr;

reg   f_ack;

reg [3:0] middle_tphqv;

always @(posedge clk or negedge rstn)

begin

  if(!rstn)

    counter <= #1 5'h0;

  else

  if(!wb_cyc_i | (counter == 5'h10) | (|middle_tphqv))

    counter <= #1 5'h0;

  else

    counter <= #1 counter + 1;

end

always @(posedge clk or negedge rstn)

begin

  if(!rstn)

    f_ack <= #1 1'h0;

  else

  if(counter == 5'h0f && !(|middle_tphqv))

    f_ack <= #1 1'h1;

  else

    f_ack <= #1 1'h0;

end

assign wb_ack_o = f_ack;

assign flash_rstn = rstn;

assign a = { ~wb_adr_i[20], wb_adr_i[19:2], counter[3:2] };

assign a_oe = (wb_cyc_i &! (|middle_tphqv));

assign wb_dat_o = data_sr;

assign oen = |middle_tphqv;

assign wen = 1'b1;

/* SIMON */

//assign cen = |middle_tphqv | (counter[1:0] == 2'b01);

assign cen = |middle_tphqv | (counter[1:0] == 2'b01) | (counter[4:0] == 5'b0);

assign wb_err_o = 1'b0;

// synopsys translate_off

integer fflash;

initial fflash = $fopen("flash.log");

always @(posedge clk)

        if (wb_cyc_i & !(|middle_tphqv)) begin // wb_ack_o should be qualified with wb_stb_i as well however OR1200 doesn't do this currently

                if (wb_stb_i & wb_we_i) begin

//      $fdisplay(fflash, "%t Trying to write into flash at %h", $time, wb_adr_i);

//      #100 $finish;

                end else if (wb_ack_o)

                        $fdisplay(fflash, "%t [%h] -> read %h", $time, wb_adr_i, wb_dat_o);

        end

// synopsys translate_on

always @(posedge clk or negedge rstn)

        if (!rstn)

                middle_tphqv <= #1 4'hf;

        else if (middle_tphqv)

                middle_tphqv <= #1 middle_tphqv - 1;

always @(posedge clk or negedge rstn)

begin

  if (!rstn) data_sr <= #1 32'b0;

  else

  if (counter[1:0] == 2'h3)

    begin

      case (counter[3:2])

        2'h0 : data_sr[31:24] <= #1 d;

        2'h1 : data_sr[23:16] <= #1 d;

        2'h2 : data_sr[15:8]  <= #1 d;

        2'h3 : data_sr[7:0]   <= #1 d;

        default : data_sr <= #1 32'bx;

      endcase

    end

end

endmodule

`endif