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/*
 * tsu.v
 * 
 * Copyright (c) 2012, BABY&HW. All rights reserved.
 *
 * This library 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 library 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 library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301  USA
 */
 
`timescale 1ns/1ns
 
module tsu (
    input       rst,
 
    input       gmii_clk,
    input       gmii_ctrl,
    input [7:0] gmii_data,
    input       giga_mode,
 
    input [7:0] ptp_msgid_mask,
 
    input        rtc_timer_clk,
    input [79:0] rtc_timer_in,  // timeStamp1s_48bit + timeStamp1ns_32bit
 
    input         q_rst,
    input         q_rd_clk,
    input         q_rd_en,
    output [  7:0] q_rd_stat,
    output [127:0] q_rd_data  // null_16bit + timeStamp1s_48bit + timeStamp1ns_32bit + msgId_4bit + ckSum_12bit + seqId_16bit 
);
 
// mii to gmii converter
reg nibble_h;
always @(posedge rst or posedge gmii_clk) begin
  if (rst)
    nibble_h <= 1'b0;
  else if (gmii_ctrl)
    nibble_h <= !nibble_h;
end
 
reg       gmii_ctrl_conv;
reg [7:0] gmii_data_conv;
always @(posedge rst or posedge gmii_clk) begin
  if (rst) begin
    gmii_ctrl_conv <= 1'b0;
    gmii_data_conv <= 8'd0;
  end
  else begin
    if (giga_mode) begin
      gmii_ctrl_conv      <= gmii_ctrl;
      gmii_data_conv[7:0] <= gmii_data[7:0];
    end
    else begin
      // 4b-8b datapath gearbox
      if (gmii_ctrl) begin
        gmii_ctrl_conv      <= ( nibble_h)? 1'b1:1'b0;
        gmii_data_conv[7:4] <= ( nibble_h)? gmii_data[3:0]:gmii_data_conv[7:4];
        gmii_data_conv[3:0] <= (!nibble_h)? gmii_data[3:0]:gmii_data_conv[3:0];
      end
      else begin
        gmii_ctrl_conv      <= 1'b0;
        gmii_data_conv[7:4] <= gmii_data_conv[7:4];
        gmii_data_conv[3:0] <= gmii_data_conv[3:0];
      end
    end
  end
end
 
// buffer gmii input
reg       gmii_ctrl_conv_d1, gmii_ctrl_conv_d2, gmii_ctrl_conv_d3, gmii_ctrl_conv_d4,
          gmii_ctrl_conv_d5, gmii_ctrl_conv_d6, gmii_ctrl_conv_d7, gmii_ctrl_conv_d8,
          gmii_ctrl_conv_d9, gmii_ctrl_conv_da;
reg [7:0] gmii_data_conv_d1, gmii_data_conv_d2, gmii_data_conv_d3, gmii_data_conv_d4,
          gmii_data_conv_d5, gmii_data_conv_d6, gmii_data_conv_d7, gmii_data_conv_d8,
          gmii_data_conv_d9, gmii_data_conv_da;
always @(posedge rst or posedge gmii_clk) begin
  if (rst) begin
    gmii_ctrl_conv_d1 <= 1'b0;
    gmii_ctrl_conv_d2 <= 1'b0;
    gmii_ctrl_conv_d3 <= 1'b0;
    gmii_ctrl_conv_d4 <= 1'b0;
    gmii_ctrl_conv_d5 <= 1'b0;
    gmii_ctrl_conv_d6 <= 1'b0;
    gmii_ctrl_conv_d7 <= 1'b0;
    gmii_ctrl_conv_d8 <= 1'b0;
    gmii_ctrl_conv_d9 <= 1'b0;
    gmii_ctrl_conv_da <= 1'b0;
    gmii_data_conv_d1 <= 8'd0;
    gmii_data_conv_d2 <= 8'd0;
    gmii_data_conv_d3 <= 8'd0;
    gmii_data_conv_d4 <= 8'd0;
    gmii_data_conv_d5 <= 8'd0;
    gmii_data_conv_d6 <= 8'd0;
    gmii_data_conv_d7 <= 8'd0;
    gmii_data_conv_d8 <= 8'd0;
    gmii_data_conv_d9 <= 8'd0;
    gmii_data_conv_da <= 8'd0;
  end
  else begin
    gmii_ctrl_conv_d1 <= gmii_ctrl_conv;
    gmii_ctrl_conv_d2 <= gmii_ctrl_conv_d1;
    gmii_ctrl_conv_d3 <= gmii_ctrl_conv_d2;
    gmii_ctrl_conv_d4 <= gmii_ctrl_conv_d3;
    gmii_ctrl_conv_d5 <= gmii_ctrl_conv_d4;
    gmii_ctrl_conv_d6 <= gmii_ctrl_conv_d5;
    gmii_ctrl_conv_d7 <= gmii_ctrl_conv_d6;
    gmii_ctrl_conv_d8 <= gmii_ctrl_conv_d7;
    gmii_ctrl_conv_d9 <= gmii_ctrl_conv_d8;
    gmii_ctrl_conv_da <= gmii_ctrl_conv_d9;
    gmii_data_conv_d1 <= gmii_data_conv;
    gmii_data_conv_d2 <= gmii_data_conv_d1;
    gmii_data_conv_d3 <= gmii_data_conv_d2;
    gmii_data_conv_d4 <= gmii_data_conv_d3;
    gmii_data_conv_d5 <= gmii_data_conv_d4;
    gmii_data_conv_d6 <= gmii_data_conv_d5;
    gmii_data_conv_d7 <= gmii_data_conv_d6;
    gmii_data_conv_d8 <= gmii_data_conv_d7;
    gmii_data_conv_d9 <= gmii_data_conv_d8;
    gmii_data_conv_da <= gmii_data_conv_d9;
  end
end
 
// choose buffered gmii input
reg       int_gmii_ctrl;
reg       int_gmii_ctrl_d1, int_gmii_ctrl_d2, int_gmii_ctrl_d3, int_gmii_ctrl_d4,
          int_gmii_ctrl_d5;
reg [7:0] int_gmii_data;
reg [7:0] int_gmii_data_d1, int_gmii_data_d2, int_gmii_data_d3, int_gmii_data_d4,
          int_gmii_data_d5;
always @(posedge rst or posedge gmii_clk) begin
  if (rst) begin
    int_gmii_ctrl    <= 1'b0;
    int_gmii_data    <= 8'h00;
    int_gmii_ctrl_d1 <= 1'b0;
    int_gmii_data_d1 <= 8'h00;
    int_gmii_ctrl_d2 <= 1'b0;
    int_gmii_data_d2 <= 8'h00;
    int_gmii_ctrl_d3 <= 1'b0;
    int_gmii_data_d3 <= 8'h00;
    int_gmii_ctrl_d4 <= 1'b0;
    int_gmii_data_d4 <= 8'h00;
    int_gmii_ctrl_d5 <= 1'b0;
    int_gmii_data_d5 <= 8'h00;
  end
  else begin
    if (giga_mode) begin
      int_gmii_ctrl    <= gmii_ctrl_conv;
      int_gmii_data    <= gmii_data_conv;
      int_gmii_ctrl_d1 <= gmii_ctrl_conv_d1;
      int_gmii_data_d1 <= gmii_data_conv_d1;
      int_gmii_ctrl_d2 <= gmii_ctrl_conv_d2;
      int_gmii_data_d2 <= gmii_data_conv_d2;
      int_gmii_ctrl_d3 <= gmii_ctrl_conv_d3;
      int_gmii_data_d3 <= gmii_data_conv_d3;
      int_gmii_ctrl_d4 <= gmii_ctrl_conv_d4;
      int_gmii_data_d4 <= gmii_data_conv_d4;
      int_gmii_ctrl_d5 <= gmii_ctrl_conv_d5;
      int_gmii_data_d5 <= gmii_data_conv_d5;
    end
    else begin
      int_gmii_ctrl    <= gmii_ctrl_conv;
      int_gmii_data    <= gmii_data_conv;
      int_gmii_ctrl_d1 <= gmii_ctrl_conv_d2;
      int_gmii_data_d1 <= gmii_data_conv_d2;
      int_gmii_ctrl_d2 <= gmii_ctrl_conv_d4;
      int_gmii_data_d2 <= gmii_data_conv_d4;
      int_gmii_ctrl_d3 <= gmii_ctrl_conv_d6;
      int_gmii_data_d3 <= gmii_data_conv_d6;
      int_gmii_ctrl_d4 <= gmii_ctrl_conv_d8;
      int_gmii_data_d4 <= gmii_data_conv_d8;
      int_gmii_ctrl_d5 <= gmii_ctrl_conv_da;
      int_gmii_data_d5 <= gmii_data_conv_da;
    end
  end
end
 
// ptp CDC time stamping
wire ts_req = int_gmii_ctrl;  // TODO: check frame start delimiter
reg  ts_req_d1, ts_req_d2, ts_req_d3;
always @(posedge rst or posedge rtc_timer_clk) begin
  if (rst) begin
    ts_req_d1 <= 1'b0;
    ts_req_d2 <= 1'b0;
    ts_req_d3 <= 1'b0;
  end
  else begin
    ts_req_d1 <= ts_req;
    ts_req_d2 <= ts_req_d1;
    ts_req_d3 <= ts_req_d2;
  end
end
reg [79:0] rtc_time_stamp;
always @(posedge rst or posedge rtc_timer_clk) begin
  if (rst)
    rtc_time_stamp <= 80'd0;
  else 
    if (ts_req_d2 & !ts_req_d3)
      rtc_time_stamp <= rtc_timer_in;
end
reg ts_ack, ts_ack_clr;
always @(posedge ts_ack_clr or posedge rtc_timer_clk) begin
  if (ts_ack_clr)
    ts_ack <= 1'b0;
  else
    if (ts_req_d2 & !ts_req_d3)
      ts_ack <= 1'b1;
end
 
reg ts_ack_d1, ts_ack_d2, ts_ack_d3;
always @(posedge rst or posedge gmii_clk) begin
  if (rst) begin
    ts_ack_d1 <= 1'b0;
    ts_ack_d2 <= 1'b0;
    ts_ack_d3 <= 1'b0;
  end
  else begin
    ts_ack_d1 <= ts_ack;
    ts_ack_d2 <= ts_ack_d1;
    ts_ack_d3 <= ts_ack_d2;
  end
end
reg [79:0] tsu_time_stamp;
always @(posedge rst or posedge gmii_clk) begin
  if (rst) begin
    tsu_time_stamp <= 80'd0;
    ts_ack_clr      <= 1'b0;
  end
  else begin
    if (ts_ack_d2 & !ts_ack_d3) begin
      tsu_time_stamp <= rtc_time_stamp;
      ts_ack_clr      <= 1'b1;
    end
    else begin
      tsu_time_stamp <= tsu_time_stamp;
      ts_ack_clr      <= 1'b0;
    end
  end
end
 
// 8b-32b datapath gearbox
reg        int_valid;
reg        int_sop, int_eop;
reg [ 1:0] int_bcnt, int_mod;
reg [31:0] int_data;
always @(posedge rst or posedge gmii_clk) begin
  if (rst)
    int_bcnt <= 2'd0;
  else
    if      ( int_gmii_ctrl & !int_gmii_ctrl_d1)
      int_bcnt <= 2'd0;  // clear on sop
    else if ( int_gmii_ctrl)
      int_bcnt <= int_bcnt + 2'd1;  // increment
    else if (!int_gmii_ctrl & int_gmii_ctrl_d3 & (int_bcnt!=2'd0))
      int_bcnt <= int_bcnt + 2'd1;  // end on eop with mod
end
always @(posedge rst or posedge gmii_clk) begin
  if (rst) begin
    int_data  <= 32'd0;
    int_valid <=  1'b0;
    int_mod   <=  2'd0;
  end
  else begin
    if (int_gmii_ctrl) begin
      int_data[ 7: 0] <= (int_bcnt==2'd3)? int_gmii_data_d1:int_data[ 7: 0];
      int_data[15: 8] <= (int_bcnt==2'd2)? int_gmii_data_d1:int_data[15: 8];
      int_data[23:16] <= (int_bcnt==2'd1)? int_gmii_data_d1:int_data[23:16];
      int_data[31:24] <= (int_bcnt==2'd0)? int_gmii_data_d1:int_data[31:24];
    end
 
    if (int_gmii_ctrl & int_bcnt==2'd3)
      int_valid <= 1'b1;
    else
      int_valid <= 1'b0;
 
    if (int_gmii_ctrl_d1 & !int_gmii_ctrl_d2)
      int_mod <= 2'd0;
    else if (!int_gmii_ctrl_d1 & int_gmii_ctrl_d2)
      int_mod <= int_bcnt;
 
    if (int_gmii_ctrl_d4 & !int_gmii_ctrl_d5 & int_bcnt==2'd3)
      int_sop <= 1'b1;
    else
      int_sop <= 1'b0;
 
    if (!int_gmii_ctrl   &  int_gmii_ctrl_d3 & int_bcnt==2'd3)
      int_eop <= 1'b1;
    else
      int_eop <= 1'b0;
 
  end
end
 
reg [31:0] int_data_d1;
reg        int_valid_d1;
reg        int_sop_d1;
reg        int_eop_d1;
reg [ 1:0] int_mod_d1;
always @(posedge rst or posedge gmii_clk) begin
  if (rst) begin
    int_data_d1  <= 32'h00000000;
    int_valid_d1 <= 1'b0;
    int_sop_d1   <= 1'b0;
    int_eop_d1   <= 1'b0;
    int_mod_d1   <= 2'b00;
  end
  else begin
    if (int_valid) begin
      int_data_d1  <= int_data;
      int_mod_d1   <= int_mod;
    end
      int_valid_d1 <= int_valid;
      int_sop_d1   <= int_sop;
      int_eop_d1   <= int_eop;
  end
end
 
// ptp packet parser here
// works at 1/4 gmii_clk frequency, needs multicycle timing constraint
wire        ptp_found;
wire [31:0] ptp_infor;
ptp_parser parser(
  .clk(gmii_clk),
  .rst(rst),
  .int_data(int_data_d1),
  .int_valid(int_valid_d1),
  .int_sop(int_sop_d1),
  .int_eop(int_eop_d1),
  .int_mod(int_mod_d1),
  .ptp_msgid_mask(ptp_msgid_mask),
  .ptp_found(ptp_found),
  .ptp_infor(ptp_infor)
);
 
// ptp time stamp dcfifo
wire q_wr_clk = gmii_clk;
wire q_wr_en = ptp_found && int_eop_d1;
wire [127:0] q_wr_data = {16'd0, tsu_time_stamp, ptp_infor};  // 16+80+32 bit
wire [3:0] q_wrusedw;
wire [3:0] q_rdusedw;
wire q_wr_full;
wire q_rd_empty;
 
ptp_queue queue(
  .aclr(q_rst),
 
  .wrclk(q_wr_clk),
  .wrreq(q_wr_en && !q_wr_full),  // write with overflow protection
  .data(q_wr_data),
  .wrfull(q_wr_full),
  .wrusedw(q_wrusedw),
 
  .rdclk(q_rd_clk),
  .rdreq(q_rd_en && !q_rd_empty),  // read with underflow protection
  .q(q_rd_data),
  .rdempty(q_rd_empty),
  .rdusedw(q_rdusedw)
);
 
assign q_rd_stat = {4'd0, q_rdusedw};
 
endmodule