Subversion Repositories pcie_sg_dma

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

// Project    : Virtex-6 Integrated Block for PCI Express

// File       : pcie_reset_delay_v6.v

//--

//-- Description: sys_reset_n delay (20ms) for Virtex6 PCIe Block

//--

//--

//--

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

`timescale 1ns/1ns

module pcie_reset_delay_v6 # (

  parameter PL_FAST_TRAIN = "FALSE",

  parameter REF_CLK_FREQ = 0   // 0 - 100 MHz, 1 - 125 MHz, 2 - 250 MHz

)

(

  input  wire        ref_clk,

  input  wire        sys_reset_n,

  output             delayed_sys_reset_n

);

  parameter TCQ = 1;

  localparam         TBIT =  (PL_FAST_TRAIN == "FALSE") ?  ((REF_CLK_FREQ == 1) ? 20: (REF_CLK_FREQ == 0) ? 20 : 21) : 2;

  reg [7:0]          reg_count_7_0;

  reg [7:0]          reg_count_15_8;

  reg [7:0]          reg_count_23_16;

  wire [23:0]        concat_count;

  assign concat_count = {reg_count_23_16, reg_count_15_8, reg_count_7_0};

  always @(posedge ref_clk or negedge sys_reset_n) begin

    if (!sys_reset_n) begin

      reg_count_7_0 <= #TCQ 8'h0;

      reg_count_15_8 <= #TCQ 8'h0;

      reg_count_23_16 <= #TCQ 8'h0;

    end else begin

      if (delayed_sys_reset_n != 1'b1) begin

        reg_count_7_0   <= #TCQ reg_count_7_0 + 1'b1;

        reg_count_15_8  <= #TCQ (reg_count_7_0 == 8'hff)? reg_count_15_8  + 1'b1 : reg_count_15_8 ;

        reg_count_23_16 <= #TCQ ((reg_count_15_8 == 8'hff) & (reg_count_7_0 == 8'hff)) ? reg_count_23_16 + 1'b1 : reg_count_23_16;

      end

    end

  end

  assign delayed_sys_reset_n = concat_count[TBIT];

endmodule