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//////////////////////////////////////////////////////////////////////

////                                                              ////

////  OMS 8051 cores UART Interface Module                        ////

////                                                              ////

////  This file is part of the OMS 8051 cores project             ////

////  http://www.opencores.org/cores/oms8051mini/                 ////

////                                                              ////

////  Description                                                 ////

////  OMS 8051 definitions.                                       ////

////                                                              ////

////  To Do:                                                      ////

////    nothing                                                   ////

////                                                              ////

////  Author(s):                                                  ////

////      - Dinesh Annayya, dinesha@opencores.org                 ////

////                                                              ////

////  Revision :                                                  //// 

////     v-0.0 : Nov 26, 2016                                     ////

////       1. Initial version picked from                         ////

////       http://www.opencores.org/cores/turbo8051/              ////

////     v-0.1 : Nov 28, 2016                                     ////

////       1. Register access for Read/Write fifo & baudrate      ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

////                                                              ////

//// Copyright (C) 2000 Authors and OPENCORES.ORG                 ////

////                                                              ////

//// This source file may be used and distributed without         ////

//// restriction provided that this copyright statement is not    ////

//// removed from the file and that any derivative work contains  ////

//// the original copyright notice and the associated disclaimer. ////

////                                                              ////

//// This source file 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 source 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 source; if not, download it   ////

//// from http://www.opencores.org/lgpl.shtml                     ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

module uart_cfg (

             mclk,

             reset_n,

        // Reg Bus Interface Signal

             reg_cs,

             reg_wr,

             reg_addr,

             reg_wdata,

             reg_be,

            // Outputs

            reg_rdata,

            reg_ack,

         // Uart Tx fifo interface

            tx_fifo_full,

            tx_fifo_wr_en,

            tx_fifo_data,

         // Uart Rx fifo interface

            rx_fifo_empty,

            rx_fifo_rd_en,

            rx_fifo_data,

       // configuration

            cfg_tx_enable,

            cfg_rx_enable,

            cfg_stop_bit ,

            cfg_pri_mod  ,

            cfg_baud_16x ,

            frm_error_o,

            par_error_o,

            rx_fifo_full_err_o

        );

input         mclk;

input         reset_n;

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

// Uart Tx fifo interface

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

input            tx_fifo_full;

output           tx_fifo_wr_en;

output [7:0]     tx_fifo_data;

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

// Uart Rx fifo interface

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

input            rx_fifo_empty;

output           rx_fifo_rd_en;

input [7:0]      rx_fifo_data;

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

// configuration

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

output        cfg_tx_enable       ; // Tx Enable

output        cfg_rx_enable       ; // Rx Enable

output        cfg_stop_bit        ; // 0 -> 1 Stop, 1 -> 2 Stop

output  [1:0] cfg_pri_mod         ; // priority mode, 0 -> nop, 1 -> Even, 2 -> Odd

output  [11:0] cfg_baud_16x       ; // 16x Baud clock config

input         frm_error_o         ; // framing error

input         par_error_o         ; // par error

input         rx_fifo_full_err_o  ; // rx fifo full error

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

// Reg Bus Interface Signal

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

input             reg_cs         ;

input             reg_wr         ;

input [3:0]       reg_addr       ;

input [31:0]      reg_wdata      ;

input [3:0]       reg_be         ;

// Outputs

output [31:0]     reg_rdata      ;

output            reg_ack     ;

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

// Internal Wire Declarations

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

wire           sw_rd_en;

wire           sw_wr_en;

wire  [3:0]    sw_addr ; // addressing 16 registers

wire  [3:0]    wr_be   ;

reg   [31:0]  reg_rdata      ;

reg           reg_ack     ;

wire [31:0]    reg_0;  // Software_Reg_0

wire [31:0]    reg_1;  // Software-Reg_1

wire [31:0]    reg_2;  // Software-Reg_2

wire [31:0]    reg_3;  // Software-Reg_3

wire [31:0]    reg_4;  // Software-Reg_4

wire [31:0]    reg_5;  // Software-Reg_5

wire [31:0]    reg_6;  // Software-Reg_6

wire [31:0]    reg_7;  // Software-Reg_7

wire [31:0]    reg_8;  // Software-Reg_8

wire [31:0]    reg_9;  // Software-Reg_9

wire [31:0]    reg_10; // Software-Reg_10

wire [31:0]    reg_11; // Software-Reg_11

wire [31:0]    reg_12; // Software-Reg_12

wire [31:0]    reg_13; // Software-Reg_13

wire [31:0]    reg_14; // Software-Reg_14

wire [31:0]    reg_15; // Software-Reg_15

reg  [31:0]    reg_out;

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

// Main code starts here

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

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

// Internal Logic Starts here

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

    assign sw_addr       = reg_addr [3:0];

    assign sw_rd_en      = reg_cs & !reg_wr;

    assign sw_wr_en      = reg_cs & reg_wr;

    assign wr_be         = reg_be;

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

// Read path mux

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

always @ (posedge mclk or negedge reset_n)

begin : preg_out_Seq

   if (reset_n == 1'b0)

   begin

      reg_rdata [31:0]  <= 32'h0000_0000;

      reg_ack           <= 1'b0;

   end

   else if (sw_rd_en && !reg_ack)

   begin

      reg_rdata [31:0]  <= reg_out [31:0];

      reg_ack           <= 1'b1;

   end

   else if (sw_wr_en && !reg_ack)

      reg_ack           <= 1'b1;

   else

   begin

      reg_ack        <= 1'b0;

   end

end

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

// register read enable and write enable decoding logic

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

wire   sw_wr_en_0 = sw_wr_en & (sw_addr == 4'h0);

wire   sw_rd_en_0 = sw_rd_en & (sw_addr == 4'h0);

wire   sw_wr_en_1 = sw_wr_en & (sw_addr == 4'h1);

wire   sw_rd_en_1 = sw_rd_en & (sw_addr == 4'h1);

wire   sw_wr_en_2 = sw_wr_en & (sw_addr == 4'h2);

wire   sw_rd_en_2 = sw_rd_en & (sw_addr == 4'h2);

wire   sw_wr_en_3 = sw_wr_en & (sw_addr == 4'h3);

wire   sw_rd_en_3 = sw_rd_en & (sw_addr == 4'h3);

wire   sw_wr_en_4 = sw_wr_en & (sw_addr == 4'h4);

wire   sw_rd_en_4 = sw_rd_en & (sw_addr == 4'h4);

wire   sw_wr_en_5 = sw_wr_en & (sw_addr == 4'h5);

wire   sw_rd_en_5 = sw_rd_en & (sw_addr == 4'h5);

wire   sw_wr_en_6 = sw_wr_en & (sw_addr == 4'h6);

wire   sw_rd_en_6 = sw_rd_en & (sw_addr == 4'h6);

wire   sw_wr_en_7 = sw_wr_en & (sw_addr == 4'h7);

wire   sw_rd_en_7 = sw_rd_en & (sw_addr == 4'h7);

wire   sw_wr_en_8 = sw_wr_en & (sw_addr == 4'h8);

wire   sw_rd_en_8 = sw_rd_en & (sw_addr == 4'h8);

wire   sw_wr_en_9 = sw_wr_en & (sw_addr == 4'h9);

wire   sw_rd_en_9 = sw_rd_en & (sw_addr == 4'h9);

wire   sw_wr_en_10 = sw_wr_en & (sw_addr == 4'hA);

wire   sw_rd_en_10 = sw_rd_en & (sw_addr == 4'hA);

wire   sw_wr_en_11 = sw_wr_en & (sw_addr == 4'hB);

wire   sw_rd_en_11 = sw_rd_en & (sw_addr == 4'hB);

wire   sw_wr_en_12 = sw_wr_en & (sw_addr == 4'hC);

wire   sw_rd_en_12 = sw_rd_en & (sw_addr == 4'hC);

wire   sw_wr_en_13 = sw_wr_en & (sw_addr == 4'hD);

wire   sw_rd_en_13 = sw_rd_en & (sw_addr == 4'hD);

wire   sw_wr_en_14 = sw_wr_en & (sw_addr == 4'hE);

wire   sw_rd_en_14 = sw_rd_en & (sw_addr == 4'hE);

wire   sw_wr_en_15 = sw_wr_en & (sw_addr == 4'hF);

wire   sw_rd_en_15 = sw_rd_en & (sw_addr == 4'hF);

always @( *)

begin : preg_sel_Com

  reg_out [31:0] = 32'd0;

  case (sw_addr [3:0])

    4'b0000 : reg_out [31:0] = reg_0 [31:0];

    4'b0001 : reg_out [31:0] = reg_1 [31:0];

    4'b0010 : reg_out [31:0] = reg_2 [31:0];

    4'b0011 : reg_out [31:0] = reg_3 [31:0];

    4'b0100 : reg_out [31:0] = reg_4 [31:0];

    4'b0101 : reg_out [31:0] = reg_5 [31:0];

    4'b0110 : reg_out [31:0] = reg_6 [31:0];

    4'b0111 : reg_out [31:0] = reg_7 [31:0];

    4'b1000 : reg_out [31:0] = reg_8 [31:0];

    4'b1001 : reg_out [31:0] = reg_9 [31:0];

    4'b1010 : reg_out [31:0] = reg_10 [31:0];

    4'b1011 : reg_out [31:0] = reg_11 [31:0];

    4'b1100 : reg_out [31:0] = reg_12 [31:0];

    4'b1101 : reg_out [31:0] = reg_13 [31:0];

    4'b1110 : reg_out [31:0] = reg_14 [31:0];

    4'b1111 : reg_out [31:0] = reg_15 [31:0];

  endcase

end

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

// Individual register assignments

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

// Logic for Register 0 : uart Control Register

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

wire [1:0]   cfg_pri_mod     = reg_0[4:3]; // priority mode, 0 -> nop, 1 -> Even, 2 -> Odd

wire         cfg_stop_bit    = reg_0[2];   // 0 -> 1 Stop, 1 -> 2 Stop

wire         cfg_rx_enable   = reg_0[1];   // Rx Enable

wire         cfg_tx_enable   = reg_0[0];   // Tx Enable

generic_register #(5,0  ) u_uart_ctrl_be0 (

              .we            ({5{sw_wr_en_0 &

                                 wr_be[0]   }}  ),

              .data_in       (reg_wdata[4:0]    ),

              .reset_n       (reset_n           ),

              .clk           (mclk              ),

              //List of Outs

              .data_out      (reg_0[4:0]        )

          );

assign reg_0[31:5] = 27'h0;

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

// Logic for Register 1 : uart interrupt status

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

stat_register u_intr_bit0 (

                 //inputs

                 . clk        (mclk            ),

                 . reset_n    (reset_n         ),

                 . cpu_we     (sw_wr_en_1 &

                               wr_be[0]        ),

                 . cpu_ack    (reg_wdata[0]    ),

                 . hware_req  (frm_error_o     ),

                 //outputs

                 . data_out   (reg_1[0]        )

                 );

stat_register u_intr_bit1 (

                 //inputs

                 . clk        (mclk            ),

                 . reset_n    (reset_n         ),

                 . cpu_we     (sw_wr_en_1 &

                               wr_be[0]        ),

                 . cpu_ack    (reg_wdata[1]    ),

                 . hware_req  (par_error_o     ),

                 //outputs

                 . data_out   (reg_1[1]        )

                 );

stat_register u_intr_bit2 (

                 //inputs

                 . clk        (mclk                ),

                 . reset_n    (reset_n             ),

                 . cpu_we     (sw_wr_en_1 &

                               wr_be[0]            ),

                 . cpu_ack    (reg_wdata[2]        ),

                 . hware_req  (rx_fifo_full_err_o  ),

                 //outputs

                 . data_out   (reg_1[2]            )

                 );

assign reg_1[31:3] = 29'h0;

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

// Logic for Register 2 :  Baud Rate Control

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

wire [11:0]   cfg_baud_16x    = reg_2[11:0];

generic_register #(12,0  ) u_uart_ctrl_reg2 (

              .we            ({12{sw_wr_en_2 &

                                 wr_be[0]   }}  ),

              .data_in       (reg_wdata[11:0]    ),

              .reset_n       (reset_n           ),

              .clk           (mclk              ),

              //List of Outs

              .data_out      (reg_2[11:0]        )

          );

assign reg_2[31:12] = 20'h0;

assign reg_3[31:0] = {30'h0,rx_fifo_empty,tx_fifo_full};

// reg_4 is tx_fifo wr

assign tx_fifo_wr_en  = sw_wr_en_4;

assign tx_fifo_data   = reg_wdata[7:0];

// reg_5 is rx_fifo read

// rx_fifo read data

assign reg_5[31:0] = {24'h0,rx_fifo_data};

assign  rx_fifo_rd_en = sw_rd_en_5;

endmodule