pluto_hdl_adi/library/util_gmii_to_rgmii/mdc_mdio.v

// ***************************************************************************
// ***************************************************************************
// Copyright 2011(c) Analog Devices, Inc.
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification,
// are permitted provided that the following conditions are met:
//     - Redistributions of source code must retain the above copyright
//       notice, this list of conditions and the following disclaimer.
//     - Redistributions in binary form must reproduce the above copyright
//       notice, this list of conditions and the following disclaimer in
//       the documentation and/or other materials provided with the
//       distribution.
//     - Neither the name of Analog Devices, Inc. nor the names of its
//       contributors may be used to endorse or promote products derived
//       from this software without specific prior written permission.
//     - The use of this software may or may not infringe the patent rights
//       of one or more patent holders.  This license does not release you
//       from the requirement that you obtain separate licenses from these
//       patent holders to use this software.
//     - Use of the software either in source or binary form, must be run
//       on or directly connected to an Analog Devices Inc. component.
//
// THIS SOFTWARE IS PROVIDED BY ANALOG DEVICES "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
// INCLUDING, BUT NOT LIMITED TO, NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS FOR A
// PARTICULAR PURPOSE ARE DISCLAIMED.
//
// IN NO EVENT SHALL ANALOG DEVICES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, INTELLECTUAL PROPERTY
// RIGHTS, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// ***************************************************************************
// ***************************************************************************

module mdc_mdio (

  mdio_mdc,
  mdio_in_w,
  mdio_in_r,

  speed_select,
  duplex_mode);

  parameter PHY_AD = 5'b10000;

  input           mdio_mdc;
  input           mdio_in_w;
  input           mdio_in_r;
  output  [ 1:0]  speed_select;
  output          duplex_mode;

  localparam IDLE     = 2'b01;
  localparam ACQUIRE  = 2'b10;

  wire        preamble;

  reg [ 1:0]  current_state = IDLE;
  reg [ 1:0]  next_state    = IDLE;
  reg [31:0]  data_in       = 32'h0;
  reg [31:0]  data_in_r     = 32'h0;
  reg [ 5:0]  data_counter  = 6'h0;
  reg [ 1:0]  speed_select  = 2'h0;
  reg         duplex_mode   = 1'h0;

  assign preamble = &data_in;

  always @(posedge mdio_mdc) begin
    current_state <= next_state;
    data_in <= {data_in[30:0], mdio_in_w};
    if (current_state == ACQUIRE) begin
      data_counter <= data_counter + 1;
    end else begin
      data_counter <= 0;
    end
    if (data_counter == 6'h1f) begin
      if (data_in[31] == 1'b0 && data_in[29:28]==2'b10 && data_in[27:23] == PHY_AD && data_in[22:18] == 5'h11) begin
        speed_select <= data_in_r[16:15] ;
        duplex_mode  <= data_in_r[14];
      end
    end
  end

  always @(negedge mdio_mdc) begin
    data_in_r <= {data_in_r[30:0], mdio_in_r};
  end

  always @(*) begin
    case (current_state)
      IDLE: begin
        if (preamble == 1 && mdio_in_w == 0) begin
          next_state <= ACQUIRE;
        end else begin
          next_state <= IDLE;
        end
      end
      ACQUIRE: begin
        if (data_counter == 6'h1f) begin
          next_state <= IDLE;
        end else begin
          next_state <= ACQUIRE;
        end
      end
      default: begin
        next_state <= IDLE;
      end
    endcase
  end

endmodule