//======================================================================
//
// i2c.v
// ------
// Configuration registers for the i2c core.
//
//
// Author: Joachim Strombergson
// Copyright (c) 2014, SUNET
//
// Redistribution and use in source and binary forms, with or
// without modification, are permitted provided that the following
// conditions are met:
//
// 1. Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
//
// 2. 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.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
// FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
// COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
// BUT NOT LIMITED TO, 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 comm_regs
(
input wire clk,
input wire rst,
input wire cs,
input wire we,
input wire [ 7 : 0] address,
input wire [31 : 0] write_data,
output wire [31 : 0] read_data
);
//----------------------------------------------------------------
// Internal constant and parameter definitions.
//----------------------------------------------------------------
// API addresses.
localparam ADDR_CORE_NAME0 = 8'h00;
localparam ADDR_CORE_NAME1 = 8'h01;
localparam ADDR_CORE_VERSION = 8'h02;
localparam ADDR_DUMMY_REG = 8'hFF; // general-purpose register
// Core ID constants.
localparam CORE_NAME0 = 32'h69326320; // "i2c "
localparam CORE_NAME1 = 32'h20202020; // " "
localparam CORE_VERSION = 32'h302e3130; // "0.10"
//----------------------------------------------------------------
// Wires.
//----------------------------------------------------------------
reg [31: 0] tmp_read_data;
// dummy register to check that you can actually write something
reg [31: 0] reg_dummy;
//----------------------------------------------------------------
// Concurrent connectivity for ports etc.
//----------------------------------------------------------------
assign read_data = tmp_read_data;
//----------------------------------------------------------------
// storage registers for mapping memory to core interface
//----------------------------------------------------------------
always @ (posedge clk or posedge rst)
begin
if (rst)
begin
reg_dummy <= {32{1'b0}};
end
else if (cs && we)
begin
// write operations
case (address)
ADDR_DUMMY_REG:
reg_dummy <= write_data;
endcase
end
end
always @*
begin
tmp_read_data = 32'h00000000;
if (cs && !we)
begin
// read operations
case (address)
ADDR_CORE_NAME0:
tmp_read_data = CORE_NAME0;
ADDR_CORE_NAME1:
tmp_read_data = CORE_NAME1;
ADDR_CORE_VERSION:
tmp_read_data = CORE_VERSION;
ADDR_DUMMY_REG:
tmp_read_data = reg_dummy;
endcase
end
end
endmodule
//======================================================================
// EOF i2c_regs.v
//======================================================================
