//======================================================================
//
// mkmif_core.v
// ------------
// The actual core module for the Master Key Memory (MKM) interface.
// The interface is implemented to use the Microchip 23K640 serial
// sram as external storage. The core acts as a SPI Master for the
// external memory including SPI clock generation.
//
// The current version of the core does not provide any functionality
// to protect against remanence.
//
//
// Author: Joachim Strombergson
// Copyright (c) 2011, 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 mkmif_core(
input wire clk,
input wire reset_n,
output wire spi_sclk,
output wire spi_cs_n,
input wire spi_do,
output wire spi_di,
input wire read_op,
input wire write_op,
input wire init_op,
output wire ready,
output wire valid,
input wire [15 : 0] sclk_div,
input wire [15 : 0] addr,
input wire [31 : 0] write_data,
output wire [31 : 0] read_data
);
//----------------------------------------------------------------
// Internal constant and parameter definitions.
//----------------------------------------------------------------
localparam SPI_READ_DATA_CMD = 8'h03;
localparam SPI_WRITE_DATA_CMD = 8'h02;
localparam SPI_READ_STATUS_CMD = 8'h05;
localparam SPI_WRITE_STATUS_CMD = 8'h01;
localparam SEQ_MODE_NO_HOLD = 8'b01000001;
localparam CTRL_IDLE = 0;
localparam CTRL_READY = 1;
localparam CTRL_READ = 2;
localparam CTRL_WRITE = 3;
localparam CTRL_INIT = 4;
localparam CTRL_OP_START = 5;
localparam CTRL_OP_WAIT = 6;
//----------------------------------------------------------------
// Registers including update variables and write enable.
//----------------------------------------------------------------
reg ready_reg;
reg ready_new;
reg ready_we;
reg valid_reg;
reg valid_new;
reg valid_we;
reg [31 : 0] read_data_reg;
reg read_data_we;
reg [3 : 0] mkmif_ctrl_reg;
reg [3 : 0] mkmif_ctrl_new;
reg mkmif_ctrl_we;
//----------------------------------------------------------------
// Wires.
//----------------------------------------------------------------
wire [31 : 0] spi_read_data;
reg [55 : 0] spi_write_data;
reg spi_set;
reg spi_start;
wire spi_ready;
reg [2 : 0] spi_length;
//----------------------------------------------------------------
// Concurrent connectivity for ports etc.
//----------------------------------------------------------------
assign ready = ready_reg;
assign valid = valid_reg;
assign read_data = read_data_reg;
//----------------------------------------------------------------
// spi
// The actual spi interfacce
//----------------------------------------------------------------
mkmif_spi spi(
.clk(clk),
.reset_n(reset_n),
.spi_sclk(spi_sclk),
.spi_cs_n(spi_cs_n),
.spi_do(spi_do),
.spi_di(spi_di),
.set(spi_set),
.start(spi_start),
.length(spi_length),
.divisor(sclk_div),
.ready(spi_ready),
.wr_data(spi_write_data),
.rd_data(spi_read_data)
);
//----------------------------------------------------------------
// reg_update
// Update functionality for all registers in the core.
// All registers are positive edge triggered with asynchronous
// active low reset.
//----------------------------------------------------------------
always @ (posedge clk or negedge reset_n)
begin
if (!reset_n)
begin
ready_reg <= 1'h0;
valid_reg <= 1'h0;
read_data_reg <= 32'h0;
mkmif_ctrl_reg <= CTRL_IDLE;
end
else
begin
if (ready_we)
ready_reg <= ready_new;
if (valid_we)
valid_reg <= valid_new;
if (read_data_we)
read_data_reg <= spi_read_data;
if (mkmif_ctrl_we)
mkmif_ctrl_reg <= mkmif_ctrl_new;
end
end // reg_update
//----------------------------------------------------------------
// mkmif_ctrl
// Main control FSM.
//----------------------------------------------------------------
always @*
begin : mkmif_ctrl
spi_set = 0;
spi_start = 0;
spi_length = 3'h0;
spi_write_data = 56'h0;
read_data_we = 0;
ready_new = 0;
ready_we = 0;
valid_new = 0;
valid_we = 0;
mkmif_ctrl_new = CTRL_IDLE;
mkmif_ctrl_we = 0;
case (mkmif_ctrl_reg)
CTRL_IDLE:
begin
mkmif_ctrl_new = CTRL_INIT;
mkmif_ctrl_we = 1;
end
CTRL_READY:
begin
ready_new = 1;
ready_we = 1;
if (read_op)
begin
ready_new = 0;
ready_we = 1;
valid_new = 0;
valid_we = 1;
mkmif_ctrl_new = CTRL_READ;
mkmif_ctrl_we = 1;
end
if (write_op)
begin
ready_new = 0;
ready_we = 1;
mkmif_ctrl_new = CTRL_WRITE;
mkmif_ctrl_we = 1;
end
if (init_op)
begin
ready_new = 0;
ready_we = 1;
mkmif_ctrl_new = CTRL_INIT;
mkmif_ctrl_we = 1;
end
end
CTRL_READ:
begin
spi_set = 1;
spi_write_data = {SPI_READ_DATA_CMD, addr, 32'h0};
spi_length = 3'h7;
mkmif_ctrl_new = CTRL_OP_START;
mkmif_ctrl_we = 1;
end
CTRL_WRITE:
begin
spi_set = 1;
spi_write_data = {SPI_WRITE_DATA_CMD, addr, write_data};
spi_length = 3'h7;
mkmif_ctrl_new = CTRL_OP_START;
mkmif_ctrl_we = 1;
end
CTRL_INIT:
begin
if (spi_ready)
begin
spi_set = 1;
spi_write_data = {SPI_WRITE_STATUS_CMD, SEQ_MODE_NO_HOLD, 40'h0};
spi_length = 3'h2;
mkmif_ctrl_new = CTRL_OP_START;
mkmif_ctrl_we = 1;
end
end
CTRL_OP_START:
begin
spi_start = 1;
mkmif_ctrl_new = CTRL_OP_WAIT;
mkmif_ctrl_we = 1;
end
CTRL_OP_WAIT:
begin
if (spi_ready)
begin
read_data_we = 1;
valid_new = 1;
valid_we = 1;
mkmif_ctrl_new = CTRL_READY;
mkmif_ctrl_we = 1;
end
end
default:
begin
end
endcase // case (mkmif_ctrl_reg)
end // mkmif_ctrl
endmodule // mkmif
//======================================================================
// EOF mkmif.v
//======================================================================
