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//////////////////////////////////////////////////////////////////////
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//// ////
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//// adbg_jsp_biu.v ////
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//// ////
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//// ////
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//// This file is part of the SoC Debug Interface. ////
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//// ////
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//// Author(s): ////
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//// Nathan Yawn (nathan.yawn@opencores.org) ////
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//// ////
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//// ////
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//// ////
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//////////////////////////////////////////////////////////////////////
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//// ////
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//// Copyright (C) 2010 Authors ////
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//// ////
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//// This source file may be used and distributed without ////
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//// restriction provided that this copyright statement is not ////
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//// removed from the file and that any derivative work contains ////
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//// the original copyright notice and the associated disclaimer. ////
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//// ////
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//// This source file is free software; you can redistribute it ////
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//// and/or modify it under the terms of the GNU Lesser General ////
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//// Public License as published by the Free Software Foundation; ////
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//// either version 2.1 of the License, or (at your option) any ////
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//// later version. ////
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//// ////
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//// This source is distributed in the hope that it will be ////
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//// useful, but WITHOUT ANY WARRANTY; without even the implied ////
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//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR ////
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//// PURPOSE. See the GNU Lesser General Public License for more ////
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//// details. ////
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//// ////
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//// You should have received a copy of the GNU Lesser General ////
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//// Public License along with this source; if not, download it ////
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//// from http://www.opencores.org/lgpl.shtml ////
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//// ////
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//////////////////////////////////////////////////////////////////////
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//
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// This is where the magic happens in the JTAG Serial Port. The serial
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// port FIFOs and counters are kept in the WishBone clock domain.
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// 'Syncflop' elements are used to synchronize strobe lines across
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// clock domains, and 'syncreg' elements keep the byte and free count
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// as current as possible in the JTAG clock domain. Also in the WB
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// clock domain is a WishBone target interface, which more or less
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// tries to emulate a 16550 without FIFOs (despite the fact that
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// FIFOs are actually present, they are opaque to the WB interface.)
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//
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// Top module
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module adbg_jsp_biu
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(
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// Debug interface signals
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tck_i,
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rst_i,
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data_i,
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data_o,
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bytes_available_o,
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bytes_free_o,
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rd_strobe_i,
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wr_strobe_i,
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// Wishbone signals
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wb_clk_i,
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wb_rst_i,
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wb_adr_i,
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wb_dat_o,
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wb_dat_i,
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wb_cyc_i,
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wb_stb_i,
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wb_sel_i,
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wb_we_i,
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wb_ack_o,
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wb_cab_i,
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wb_err_o,
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wb_cti_i,
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wb_bte_i,
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int_o
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);
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// Debug interface signals
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input tck_i;
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input rst_i;
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input [7:0] data_i; // Assume short words are in UPPER order bits!
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output [7:0] data_o;
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output [3:0] bytes_free_o;
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output [3:0] bytes_available_o;
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input rd_strobe_i;
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input wr_strobe_i;
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// Wishbone signals
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input wb_clk_i;
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input wb_rst_i;
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input [31:0] wb_adr_i;
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output [31:0] wb_dat_o;
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input [31:0] wb_dat_i;
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input wb_cyc_i;
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input wb_stb_i;
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input [3:0] wb_sel_i;
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input wb_we_i;
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output wb_ack_o;
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input wb_cab_i;
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output wb_err_o;
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input [2:0] wb_cti_i;
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input [1:0] wb_bte_i;
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output int_o;
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wire wb_ack_o;
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wire [31:0] wb_dat_o;
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wire wb_err_o;
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wire int_o;
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wire [7:0] data_o;
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wire [3:0] bytes_free_o;
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wire [3:0] bytes_available_o;
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// Registers
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reg [7:0] data_in;
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reg [7:0] rdata;
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reg wen_tff;
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reg ren_tff;
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// Wires
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wire wb_fifo_ack;
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wire [3:0] wr_bytes_free;
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wire [3:0] rd_bytes_avail;
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wire [3:0] wr_bytes_avail; // used to generate wr_fifo_not_empty
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wire rd_bytes_avail_not_zero;
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wire ren_sff_out;
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wire [7:0] rd_fifo_data_out;
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wire [7:0] data_to_wb;
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wire [7:0] data_from_wb;
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wire wr_fifo_not_empty; // this is for the WishBone interface LSR register
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wire rcvr_fifo_rst; // rcvr in the WB sense, opposite most of the rest of this file
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wire xmit_fifo_rst; // ditto
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// Control Signals (FSM outputs)
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reg wda_rst; // reset wdata_avail SFF
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reg wpp; // Write FIFO PUSH (1) or POP (0)
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reg w_fifo_en; // Enable write FIFO
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reg ren_rst; // reset 'pop' SFF
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reg rdata_en; // enable 'rdata' register
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reg rpp; // read FIFO PUSH (1) or POP (0)
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reg r_fifo_en; // enable read FIFO
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reg r_wb_ack; // read FSM acks WB transaction
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reg w_wb_ack; // write FSM acks WB transaction
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// Indicators to FSMs
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wire wdata_avail; // JTAG side has data available
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wire wb_rd; // WishBone requests read
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wire wb_wr; // WishBone requests write
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wire pop; // JTAG side received a byte, pop and get next
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wire rcz; // zero bytes available in read FIFO
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//////////////////////////////////////////////////////
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// TCK clock domain
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// There is no FSM here, just signal latching and clock
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// domain synchronization
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assign data_o = rdata;
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// Write enable (WEN) toggle FF
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always @ (posedge tck_i or posedge rst_i)
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begin
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if(rst_i) wen_tff <= 1'b0;
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else if(wr_strobe_i) wen_tff <= ~wen_tff;
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end
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// Read enable (REN) toggle FF
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always @ (posedge tck_i or posedge rst_i)
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begin
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if(rst_i) ren_tff <= 1'b0;
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else if(rd_strobe_i) ren_tff <= ~ren_tff;
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end
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// Write data register
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always @ (posedge tck_i or posedge rst_i)
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begin
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if(rst_i) data_in <= 8'h0;
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else if(wr_strobe_i) data_in <= data_i;
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end
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///////////////////////////////////////////////////////
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// Wishbone clock domain
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// Combinatorial assignments
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assign rd_bytes_avail_not_zero = !(rd_bytes_avail == 4'h0);
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assign pop = ren_sff_out & rd_bytes_avail_not_zero;
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assign rcz = ~rd_bytes_avail_not_zero;
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assign wb_fifo_ack = r_wb_ack | w_wb_ack;
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assign wr_fifo_not_empty = !(wr_bytes_avail == 4'h0);
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// rdata register
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always @ (posedge wb_clk_i or posedge rst_i)
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begin
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if(rst_i) rdata <= 8'h0;
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else if(rdata_en) rdata <= rd_fifo_data_out;
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end
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// WEN SFF
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syncflop wen_sff (
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.DEST_CLK(wb_clk_i),
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.D_SET(1'b0),
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.D_RST(wda_rst),
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.RESET(rst_i),
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.TOGGLE_IN(wen_tff),
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.D_OUT(wdata_avail)
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);
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// REN SFF
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syncflop ren_sff (
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.DEST_CLK(wb_clk_i),
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.D_SET(1'b0),
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.D_RST(ren_rst),
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.RESET(rst_i),
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.TOGGLE_IN(ren_tff),
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.D_OUT(ren_sff_out)
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);
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// 'free space available' syncreg
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syncreg freespace_syncreg (
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.CLKA(wb_clk_i),
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.CLKB(tck_i),
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.RST(rst_i),
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.DATA_IN(wr_bytes_free),
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.DATA_OUT(bytes_free_o)
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);
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// 'bytes available' syncreg
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syncreg bytesavail_syncreg (
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.CLKA(wb_clk_i),
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.CLKB(tck_i),
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.RST(rst_i),
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.DATA_IN(rd_bytes_avail),
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.DATA_OUT(bytes_available_o)
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);
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// write FIFO
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bytefifo wr_fifo (
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.CLK(wb_clk_i),
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.RST(rst_i | rcvr_fifo_rst), // rst_i from JTAG clk domain, rcvr_fifo_rst from WB, RST is async reset
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.DATA_IN(data_in),
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.DATA_OUT(data_to_wb),
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.PUSH_POPn(wpp),
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.EN(w_fifo_en),
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.BYTES_AVAIL(wr_bytes_avail),
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.BYTES_FREE(wr_bytes_free)
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);
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// read FIFO
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bytefifo rd_fifo (
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.CLK(wb_clk_i),
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.RST(rst_i | xmit_fifo_rst), // rst_i from JTAG clk domain, xmit_fifo_rst from WB, RST is async reset
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.DATA_IN(data_from_wb),
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.DATA_OUT(rd_fifo_data_out),
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.PUSH_POPn(rpp),
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.EN(r_fifo_en),
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.BYTES_AVAIL(rd_bytes_avail),
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.BYTES_FREE()
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);
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/////////////////////////////////////////////////////
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// State machine for the read FIFO
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reg [1:0] rd_fsm_state;
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reg [1:0] next_rd_fsm_state;
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`define STATE_RD_IDLE 2'h0
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`define STATE_RD_PUSH 2'h1
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`define STATE_RD_POP 2'h2
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`define STATE_RD_LATCH 2'h3
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// Sequential bit
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always @ (posedge wb_clk_i or posedge rst_i)
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begin
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if(rst_i) rd_fsm_state <= `STATE_RD_IDLE;
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else rd_fsm_state <= next_rd_fsm_state;
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end
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// Determination of next state (combinatorial)
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always @ (rd_fsm_state or wb_wr or pop or rcz)
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begin
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case (rd_fsm_state)
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`STATE_RD_IDLE:
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begin
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if(wb_wr) next_rd_fsm_state <= `STATE_RD_PUSH;
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else if (pop) next_rd_fsm_state <= `STATE_RD_POP;
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else next_rd_fsm_state <= `STATE_RD_IDLE;
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end
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`STATE_RD_PUSH:
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begin
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if(rcz) next_rd_fsm_state <= `STATE_RD_LATCH; // putting first item in fifo, move to rdata in state LATCH
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else if(pop) next_rd_fsm_state <= `STATE_RD_POP;
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else next_rd_fsm_state <= `STATE_RD_IDLE;
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end
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`STATE_RD_POP:
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begin
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next_rd_fsm_state <= `STATE_RD_LATCH; // new data at FIFO head, move to rdata in state LATCH
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end
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`STATE_RD_LATCH:
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begin
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if(wb_wr) next_rd_fsm_state <= `STATE_RD_PUSH;
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else if(pop) next_rd_fsm_state <= `STATE_RD_POP;
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else next_rd_fsm_state <= `STATE_RD_IDLE;
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end
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default:
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begin
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next_rd_fsm_state <= `STATE_RD_IDLE;
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end
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endcase
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end
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// Outputs of state machine (combinatorial)
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always @ (rd_fsm_state)
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begin
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ren_rst <= 1'b0;
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rpp <= 1'b0;
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r_fifo_en <= 1'b0;
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rdata_en <= 1'b0;
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r_wb_ack <= 1'b0;
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case (rd_fsm_state)
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`STATE_RD_IDLE:;
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`STATE_RD_PUSH:
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begin
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rpp <= 1'b1;
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r_fifo_en <= 1'b1;
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r_wb_ack <= 1'b1;
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end
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`STATE_RD_POP:
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begin
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ren_rst <= 1'b1;
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r_fifo_en <= 1'b1;
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end
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`STATE_RD_LATCH:
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begin
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rdata_en <= 1'b1;
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end
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endcase
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end
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/////////////////////////////////////////////////////
|
352 |
|
|
// State machine for the write FIFO
|
353 |
|
|
|
354 |
|
|
reg [1:0] wr_fsm_state;
|
355 |
|
|
reg [1:0] next_wr_fsm_state;
|
356 |
|
|
|
357 |
|
|
`define STATE_WR_IDLE 2'h0
|
358 |
|
|
`define STATE_WR_PUSH 2'h1
|
359 |
|
|
`define STATE_WR_POP 2'h2
|
360 |
|
|
|
361 |
|
|
|
362 |
|
|
// Sequential bit
|
363 |
|
|
always @ (posedge wb_clk_i or posedge rst_i)
|
364 |
|
|
begin
|
365 |
|
|
if(rst_i) wr_fsm_state <= `STATE_WR_IDLE;
|
366 |
|
|
else wr_fsm_state <= next_wr_fsm_state;
|
367 |
|
|
end
|
368 |
|
|
|
369 |
|
|
// Determination of next state (combinatorial)
|
370 |
|
|
always @ (wr_fsm_state or wb_rd or wdata_avail)
|
371 |
|
|
begin
|
372 |
|
|
case (wr_fsm_state)
|
373 |
|
|
|
374 |
|
|
`STATE_WR_IDLE:
|
375 |
|
|
begin
|
376 |
|
|
if(wb_rd) next_wr_fsm_state <= `STATE_WR_POP;
|
377 |
|
|
else if (wdata_avail) next_wr_fsm_state <= `STATE_WR_PUSH;
|
378 |
|
|
else next_wr_fsm_state <= `STATE_WR_IDLE;
|
379 |
|
|
end
|
380 |
|
|
|
381 |
|
|
`STATE_WR_PUSH:
|
382 |
|
|
begin
|
383 |
|
|
if(wb_rd) next_wr_fsm_state <= `STATE_WR_POP;
|
384 |
|
|
else next_wr_fsm_state <= `STATE_WR_IDLE;
|
385 |
|
|
end
|
386 |
|
|
|
387 |
|
|
`STATE_WR_POP:
|
388 |
|
|
begin
|
389 |
|
|
if(wdata_avail) next_wr_fsm_state <= `STATE_WR_PUSH;
|
390 |
|
|
else next_wr_fsm_state <= `STATE_WR_IDLE;
|
391 |
|
|
end
|
392 |
|
|
|
393 |
|
|
default:
|
394 |
|
|
begin
|
395 |
|
|
next_wr_fsm_state <= `STATE_WR_IDLE;
|
396 |
|
|
end
|
397 |
|
|
endcase
|
398 |
|
|
end
|
399 |
|
|
|
400 |
|
|
// Outputs of state machine (combinatorial)
|
401 |
|
|
always @ (wr_fsm_state)
|
402 |
|
|
begin
|
403 |
|
|
wda_rst <= 1'b0;
|
404 |
|
|
wpp <= 1'b0;
|
405 |
|
|
w_fifo_en <= 1'b0;
|
406 |
|
|
w_wb_ack <= 1'b0;
|
407 |
|
|
|
408 |
|
|
case (wr_fsm_state)
|
409 |
|
|
`STATE_WR_IDLE:;
|
410 |
|
|
|
411 |
|
|
`STATE_WR_PUSH:
|
412 |
|
|
begin
|
413 |
|
|
wda_rst <= 1'b1;
|
414 |
|
|
wpp <= 1'b1;
|
415 |
|
|
w_fifo_en <= 1'b1;
|
416 |
|
|
end
|
417 |
|
|
|
418 |
|
|
`STATE_WR_POP:
|
419 |
|
|
begin
|
420 |
|
|
w_wb_ack <= 1'b1;
|
421 |
|
|
w_fifo_en <= 1'b1;
|
422 |
|
|
end
|
423 |
|
|
|
424 |
|
|
endcase
|
425 |
|
|
|
426 |
|
|
end
|
427 |
|
|
|
428 |
|
|
////////////////////////////////////////////////////////////
|
429 |
|
|
// WishBone interface hardware
|
430 |
|
|
// Interface signals to read and write fifos:
|
431 |
|
|
// wb_rd: read strobe
|
432 |
|
|
// wb_wr: write strobe
|
433 |
|
|
// wb_fifo_ack: fifo has completed operation
|
434 |
|
|
|
435 |
|
|
wire [31:0] bus_data_lo;
|
436 |
|
|
wire [31:0] bus_data_hi;
|
437 |
|
|
wire wb_reg_ack;
|
438 |
|
|
wire rd_fifo_not_full; // "rd fifo" is the one the WB writes to
|
439 |
|
|
reg [2:0] iir_gen; // actually combinatorial
|
440 |
|
|
wire rd_fifo_becoming_empty;
|
441 |
|
|
|
442 |
|
|
// These 16550 registers are at least partly implemented
|
443 |
|
|
reg reg_dlab_bit; // part of the LCR
|
444 |
|
|
reg [3:0] reg_ier;
|
445 |
|
|
wire [2:0] reg_iir;
|
446 |
|
|
reg thr_int_arm; // used so that an IIR read can clear a transmit interrupt
|
447 |
|
|
wire [7:0] reg_lsr;
|
448 |
|
|
wire reg_dlab_bit_wren;
|
449 |
|
|
wire reg_ier_wren;
|
450 |
|
|
wire reg_iir_rden;
|
451 |
|
|
wire [7:0] reg_lcr; // the DLAB bit above is the 8th bit
|
452 |
|
|
wire reg_fcr_wren; // FCR is WR-only, at the same address as the IIR (contains SW reset bits)
|
453 |
|
|
|
454 |
|
|
// These 16550 registers are not implemented here
|
455 |
|
|
wire [7:0] reg_mcr;
|
456 |
|
|
wire [7:0] reg_msr;
|
457 |
|
|
wire [7:0] reg_scr;
|
458 |
|
|
|
459 |
|
|
// Create handshake signals to/from the FIFOs
|
460 |
|
|
assign wb_rd = wb_cyc_i & wb_stb_i & (~wb_we_i) & wb_sel_i[3] & (wb_adr_i[1:0] == 2'b00) & (~reg_dlab_bit);
|
461 |
|
|
assign wb_wr = wb_cyc_i & wb_stb_i & wb_we_i & wb_sel_i[3] & (wb_adr_i[1:0] == 2'b00) & (~reg_dlab_bit);
|
462 |
|
|
assign wb_ack_o = wb_fifo_ack | wb_reg_ack;
|
463 |
|
|
assign wb_err_o = 1'b0;
|
464 |
|
|
|
465 |
|
|
// Assign the unimplemented registers
|
466 |
|
|
assign reg_mcr = 8'h00; // These bits control modem control lines, unused here
|
467 |
|
|
assign reg_msr = 8'hB0; // CD, DSR, CTS true, RI false, no changes indicated
|
468 |
|
|
assign reg_scr = 8'h00; // scratch register.
|
469 |
|
|
|
470 |
|
|
// Create the simple / combinatorial registers
|
471 |
|
|
assign rd_fifo_not_full = !(rd_bytes_avail == 4'h8);
|
472 |
|
|
assign reg_lcr = {reg_dlab_bit, 7'h03}; // Always set for 8n1
|
473 |
|
|
assign reg_lsr = {1'b0, rd_fifo_not_full, rd_fifo_not_full, 4'b0000, wr_fifo_not_empty};
|
474 |
|
|
|
475 |
|
|
// Create enable bits for the 16550 registers that we actually implement
|
476 |
|
|
assign reg_dlab_bit_wren = wb_cyc_i & wb_stb_i & wb_we_i & wb_sel_i[0] & (wb_adr_i[2:0] == 3'b011);
|
477 |
|
|
assign reg_ier_wren = wb_cyc_i & wb_stb_i & wb_we_i & wb_sel_i[2] & (wb_adr_i[2:0] == 3'b001) & (~reg_dlab_bit);
|
478 |
|
|
assign reg_iir_rden = wb_cyc_i & wb_stb_i & (~wb_we_i) & wb_sel_i[1] & (wb_adr_i[2:0] == 3'b010);
|
479 |
|
|
assign wb_reg_ack = wb_cyc_i & wb_stb_i & (|wb_sel_i[3:0]) & (reg_dlab_bit | (wb_adr_i[2:0] != 3'b000));
|
480 |
|
|
assign reg_fcr_wren = wb_cyc_i & wb_stb_i & wb_we_i & wb_sel_i[1] & (wb_adr_i[2:0] == 3'b010);
|
481 |
|
|
assign rcvr_fifo_rst = reg_fcr_wren & wb_dat_i[9];
|
482 |
|
|
assign xmit_fifo_rst = reg_fcr_wren & wb_dat_i[10];
|
483 |
|
|
|
484 |
|
|
// Create DLAB bit
|
485 |
|
|
always @ (posedge wb_clk_i)
|
486 |
|
|
begin
|
487 |
|
|
if(wb_rst_i) reg_dlab_bit <= 1'b0;
|
488 |
|
|
else if(reg_dlab_bit_wren) reg_dlab_bit <= wb_dat_i[7];
|
489 |
|
|
end
|
490 |
|
|
|
491 |
|
|
// Create IER. We only use the two LS bits...
|
492 |
|
|
always @ (posedge wb_clk_i)
|
493 |
|
|
begin
|
494 |
|
|
if(wb_rst_i) reg_ier <= 4'h0;
|
495 |
|
|
else if(reg_ier_wren) reg_ier <= wb_dat_i[19:16];
|
496 |
|
|
end
|
497 |
|
|
|
498 |
|
|
// Create IIR (and THR INT arm bit)
|
499 |
|
|
assign rd_fifo_becoming_empty = r_fifo_en & (~rpp) & (rd_bytes_avail == 4'h1); // "rd fifo" is the WB write FIFO...
|
500 |
|
|
|
501 |
|
|
always @ (posedge wb_clk_i)
|
502 |
|
|
begin
|
503 |
|
|
if(wb_rst_i) thr_int_arm <= 1'b0;
|
504 |
|
|
else if(wb_wr | rd_fifo_becoming_empty) thr_int_arm <= 1'b1; // Set when WB write fifo becomes empty, or on a write to it
|
505 |
|
|
else if(reg_iir_rden & (~wr_fifo_not_empty)) thr_int_arm <= 1'b0;
|
506 |
|
|
end
|
507 |
|
|
|
508 |
|
|
always @ (thr_int_arm or rd_fifo_not_full or wr_fifo_not_empty)
|
509 |
|
|
begin
|
510 |
|
|
if(wr_fifo_not_empty) iir_gen <= 3'b100;
|
511 |
|
|
else if(thr_int_arm & rd_fifo_not_full) iir_gen <= 3'b010;
|
512 |
|
|
else iir_gen <= 3'b001;
|
513 |
|
|
end
|
514 |
|
|
|
515 |
51 |
nyawn |
assign reg_iir = iir_gen;
|
516 |
42 |
nyawn |
|
517 |
|
|
// Create the data lines out to the WB.
|
518 |
|
|
// Always put all 4 bytes on the WB data lines, let the master pick out what it
|
519 |
|
|
// wants.
|
520 |
|
|
assign bus_data_lo = {data_to_wb, {4'b0000, reg_ier}, {5'b00000, reg_iir}, reg_lcr};
|
521 |
|
|
assign bus_data_hi = {reg_mcr, reg_lsr, reg_msr, reg_scr};
|
522 |
|
|
assign wb_dat_o = (wb_adr_i[2]) ? bus_data_hi : bus_data_lo;
|
523 |
|
|
|
524 |
|
|
assign data_from_wb = wb_dat_i[31:24]; // Data to the FIFO
|
525 |
|
|
|
526 |
|
|
// Generate interrupt output
|
527 |
|
|
assign int_o = (rd_fifo_not_full & thr_int_arm & reg_ier[1]) | (wr_fifo_not_empty & reg_ier[0]);
|
528 |
|
|
|
529 |
|
|
endmodule
|
530 |
|
|
|