// ***************************************************************************
// ***************************************************************************
// Copyright 2011(c) Analog Devices, Inc.
// 
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// are permitted provided that the following conditions are met:
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// ***************************************************************************
// ***************************************************************************

`timescale 1ns/100ps

module axi_gpreg_clock_mon (

  // clock

  d_clk,

  // bus interface

  up_rstn,
  up_clk,
  up_wreq,
  up_waddr,
  up_wdata,
  up_wack,
  up_rreq,
  up_raddr,
  up_rdata,
  up_rack);

  // parameters

  parameter   ID = 0;

  // clock

  input           d_clk;

  // bus interface

  input           up_rstn;
  input           up_clk;
  input           up_wreq;
  input   [13:0]  up_waddr;
  input   [31:0]  up_wdata;
  output          up_wack;
  input           up_rreq;
  input   [13:0]  up_raddr;
  output  [31:0]  up_rdata;
  output          up_rack;

  // internal registers

  reg             up_d_preset = 'd0;
  reg             up_wack = 'd0;
  reg             up_d_resetn = 'd0;
  reg             up_rack = 'd0;
  reg     [31:0]  up_rdata = 'd0;

  // internal signals

  wire            up_wreq_s;
  wire            up_rreq_s;
  wire    [31:0]  up_d_count_s;
  wire            d_rst;

  // decode block select

  assign up_wreq_s = (up_waddr[13:4] == ID) ? up_wreq : 1'b0;
  assign up_rreq_s = (up_raddr[13:4] == ID) ? up_rreq : 1'b0;

  // processor write interface

  always @(negedge up_rstn or posedge up_clk) begin
    if (up_rstn == 0) begin
      up_d_preset <= 1'd1;
      up_wack <= 'd0;
      up_d_resetn <= 'd0;
    end else begin
      up_d_preset <= ~up_d_resetn;
      up_wack <= up_wreq_s;
      if ((up_wreq_s == 1'b1) && (up_waddr[3:0] == 4'h0)) begin
        up_d_resetn <= up_wdata[0];
      end
    end
  end

  // processor read interface

  always @(negedge up_rstn or posedge up_clk) begin
    if (up_rstn == 0) begin
      up_rack <= 'd0;
      up_rdata <= 'd0;
    end else begin
      up_rack <= up_rreq_s;
      if (up_rreq_s == 1'b1) begin
        case (up_raddr[3:0])
          4'b0000: up_rdata <= {31'd0, up_d_resetn};
          4'b0010: up_rdata <= up_d_count_s;
          default: up_rdata <= 32'd0;
        endcase
      end else begin
        up_rdata <= 32'd0;
      end
    end
  end

  // clock monitor

  up_clock_mon i_clock_mon (
    .up_rstn (up_rstn),
    .up_clk (up_clk),
    .up_d_count (up_d_count_s),
    .d_rst (d_rst),
    .d_clk (d_clk));

  ad_rst i_d_rst_reg (
    .preset (up_d_preset),
    .clk (d_clk),
    .rst (d_rst));

endmodule

// ***************************************************************************
// ***************************************************************************