//======================================================================
//
// Copyright (c) 2018, NORDUnet A/S 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 the NORDUnet nor the names of its contributors may
// be used to endorse or promote products derived from this software
// without specific prior written permission.
//
// 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
// HOLDER 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 ed25519_wrapper
(
input clk,
input rst_n,
input cs,
input we,
input [ 4:0] address,
input [31:0] write_data,
output [31:0] read_data
);
//
// Address Decoder
//
localparam ADDR_MSB_REGS = 1'b0;
localparam ADDR_MSB_CORE = 1'b1;
wire [0:0] addr_msb = address[4];
wire [3:0] addr_lsb = address[3:0];
//
// Output Mux
//
wire [31: 0] read_data_regs;
wire [31: 0] read_data_core;
//
// Registers
//
localparam ADDR_NAME0 = 4'h0;
localparam ADDR_NAME1 = 4'h1;
localparam ADDR_VERSION = 4'h2;
localparam ADDR_CONTROL = 4'h8; // {next, init}
localparam ADDR_STATUS = 4'h9; // {valid, ready}
localparam ADDR_DUMMY = 4'hF; // don't care
// localparam CONTROL_INIT_BIT = 0; -- not used
localparam CONTROL_NEXT_BIT = 1;
// localparam STATUS_READY_BIT = 0; -- hardcoded to always read 1
localparam STATUS_VALID_BIT = 1;
localparam CORE_NAME0 = 32'h65643235; // "ed25"
localparam CORE_NAME1 = 32'h35313920; // "519 "
localparam CORE_VERSION = 32'h302E3130; // "0.10"
//
// Registers
//
reg reg_control = 1'b0;
reg [31:0] reg_dummy;
//
// Wires
//
wire reg_status;
//
// Ed25519
//
ed25519_core_top ed25519_inst
(
.clk (clk),
.rst_n (rst_n),
.next (reg_control),
.valid (reg_status),
.bus_cs (cs && (addr_msb == ADDR_MSB_CORE)),
.bus_we (we),
.bus_addr (addr_lsb),
.bus_data_wr (write_data),
.bus_data_rd (read_data_core)
);
//
// Read Latch
//
reg [31: 0] tmp_read_data;
//
// Read/Write Interface
//
always @(posedge clk)
//
if (!rst_n) begin
//
reg_control <= 1'b0;
//
end else if (cs && (addr_msb == ADDR_MSB_REGS)) begin
//
if (we) begin
//
// Write Handler
//
case (addr_lsb)
//
ADDR_CONTROL: reg_control <= write_data[CONTROL_NEXT_BIT];
ADDR_DUMMY: reg_dummy <= write_data;
//
endcase
//
end else begin
//
// Read Handler
//
case (address)
//
ADDR_NAME0: tmp_read_data <= CORE_NAME0;
ADDR_NAME1: tmp_read_data <= CORE_NAME1;
ADDR_VERSION: tmp_read_data <= CORE_VERSION;
ADDR_CONTROL: tmp_read_data <= {{30{1'b0}}, reg_control, 1'b0};
ADDR_STATUS: tmp_read_data <= {{30{1'b0}}, reg_status, 1'b1};
ADDR_DUMMY: tmp_read_data <= reg_dummy;
//
default: tmp_read_data <= 32'h00000000;
//
endcase
//
end
//
end
//
// Register / Core Memory Selector
//
reg addr_msb_last;
always @(posedge clk)
addr_msb_last <= addr_msb;
assign read_data = (addr_msb_last == ADDR_MSB_REGS) ? tmp_read_data : read_data_core;
endmodule
