Subversion Repositories wb_to_amba

//

//

//

`timescale 1ns / 100ps

module

  wb_arm_slave_top

  #(

    parameter AWIDTH = 8,

    parameter DWIDTH = 32

  )

  (

    // -----------------------------

    // AHB interface

    input               ahb_hclk,

    input               ahb_hreset,

    output [DWIDTH-1:0] ahb_hrdata,

    output [1:0]        ahb_hresp,

    output              ahb_hready_out,

    output [15:0]       ahb_hsplit,

    input  [DWIDTH-1:0] ahb_hwdata,

    input  [AWIDTH-1:0] ahb_haddr,

    input  [2:0]        ahb_hsize,

    input               ahb_hwrite,

    input  [2:0]        ahb_hburst,

    input  [1:0]        ahb_htrans,

    input  [3:0]        ahb_hprot,

    input               ahb_hsel,

    input               ahb_hready_in,

    // -----------------------------

    // Data WISHBONE interface

    input                                 wb_ack_i,     // normal termination

    input                                 wb_err_i,     // termination w/ error

    input                                 wb_rty_i,     // termination w/ retry

    input        [DWIDTH-1:0] wb_dat_i,  // input data bus

    output                              wb_cyc_o,       // cycle valid output

    output [AWIDTH-1:0]  wb_adr_o,       // address bus outputs

    output                              wb_stb_o,       // strobe output

    output                              wb_we_o,        // indicates write transfer

    output [3:0]             wb_sel_o,   // byte select outputs

    output [DWIDTH-1:0]  wb_dat_o,       // output data bus

    output                        wb_clk_o,     // clock input

    output                        wb_rst_o      // reset input

  );

  // -----------------------------

  //  ahb_haddr & control flops

  wire flop_en = ahb_hready_in & ahb_hsel;

  reg [AWIDTH-1:0] ahb_haddr_r;

  always @ (posedge ahb_hclk)

    if ( flop_en )

      ahb_haddr_r <= ahb_haddr;

  reg [1:0] ahb_htrans_r;

  always @ (posedge ahb_hclk)

    if ( flop_en )

      ahb_htrans_r <= ahb_htrans;

  reg ahb_hwrite_r;

  always @ (posedge ahb_hclk)

    if ( flop_en )

      ahb_hwrite_r <= ahb_hwrite;

  reg [2:0] ahb_hsize_r;

  always @ (posedge ahb_hclk)

    if ( flop_en )

      ahb_hsize_r <= ahb_hsize;

  reg [2:0] ahb_hburst_r;

  always @ (posedge ahb_hclk)

    if ( flop_en )

      ahb_hburst_r <= ahb_hburst;

  // -----------------------------

  //  wb_arm_phase_fsm

  wire ahb_data_phase;

  wire fsm_error;

  wb_arm_phase_fsm i_wb_arm_phase_fsm(

                                        .ahb_hclk       (ahb_hclk),

                                        .ahb_hreset     (ahb_hreset),

                                        .ahb_hsel       (ahb_hsel),

                                        .ahb_hready_in  (ahb_hready_in),

                                        .ahb_hready_out (ahb_hready_out),

                                        .ahb_data_phase (ahb_data_phase),

                                        .fsm_error      (fsm_error)

                                      );

  // -----------------------------

  // hresp encoder

  reg [1:0] enc_hresp;

  always @(*)

    casez( { ahb_htrans_r, fsm_error } )

      { 2'b??, 1'b1 }:  enc_hresp = 2'b01;

      { 2'b11, 1'b? }:  enc_hresp = 2'b01;    // burst not supported yet

      default:          enc_hresp = 2'b00;

    endcase

  // -----------------------------

  // wb_sel encoder

  reg [3:0] enc_wb_sel;

  always @(*)

    casez( { ahb_hsize_r, ahb_haddr_r[1:0] } )

      { 3'b010, 2'b?? }:  enc_wb_sel = 4'b1111;

      { 3'b001, 2'b0? }:  enc_wb_sel = 4'b0011;

      { 3'b001, 2'b1? }:  enc_wb_sel = 4'b1100;

      { 3'b000, 2'b00 }:  enc_wb_sel = 4'b0001;

      { 3'b000, 2'b01 }:  enc_wb_sel = 4'b0010;

      { 3'b000, 2'b10 }:  enc_wb_sel = 4'b0100;

      { 3'b000, 2'b11 }:  enc_wb_sel = 4'b1000;

      default:            enc_wb_sel = 4'b0000;

    endcase

  // -----------------------------

  // outputs

  assign ahb_hresp      = enc_hresp;

  assign ahb_hready_out = wb_ack_i;

  assign ahb_hsplit     = 0;

  assign wb_sel_o       = enc_wb_sel;

  assign wb_adr_o   = ahb_haddr_r;

  assign ahb_hrdata = wb_dat_i;

  assign wb_we_o    = ahb_hwrite_r & ( (ahb_htrans_r != 2'b00) | (ahb_htrans_r != 2'b01) );

  assign wb_cyc_o   = ahb_data_phase;

  assign wb_stb_o   = ahb_data_phase;

  assign wb_dat_o   = ahb_hwdata;

  assign wb_clk_o = ahb_hclk;

  assign wb_rst_o = ~ahb_hreset;

endmodule