diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/rtl/external_avalanche_entropy.v | 383 |
1 files changed, 320 insertions, 63 deletions
diff --git a/src/rtl/external_avalanche_entropy.v b/src/rtl/external_avalanche_entropy.v index df72b3a..3f1c3f9 100644 --- a/src/rtl/external_avalanche_entropy.v +++ b/src/rtl/external_avalanche_entropy.v @@ -13,83 +13,147 @@ // // 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 +// 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 +// +// * 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 +// +// * 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 +// +// 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 external_avalanche_entropy( - input wire clk, - input wire reset_n, + input wire clk, + input wire reset_n, + + input wire cs, + input wire we, + input wire [7 : 0] address, + input wire [31 : 0] write_data, + output wire [31 : 0] read_data, + output wire error, + + input wire noise, + + input wire entropy_read, + output wire entropy_ready, + output wire [31 : 0] entropy_data, + output wire [7 : 0] debug + ); - input wire noise, - - output wire [7 : 0] debug - ); //---------------------------------------------------------------- // Internal constant and parameter definitions. //---------------------------------------------------------------- - parameter DEBUG_RATE = 32'h00300000; - - + parameter ADDR_STATUS = 8'h00; + parameter ADDR_ENTROPY = 8'h10; + parameter ADDR_POS_FLANKS = 8'h20; + parameter ADDR_NEG_FLANKS = 8'h21; + parameter ADDR_TOT_FLANKS = 8'h22; + + parameter DEBUG_RATE = 32'h00300000; + parameter SECONDS_RATE = 32'h02faf080; + + //---------------------------------------------------------------- // Registers including update variables and write enable. //---------------------------------------------------------------- - reg noise_sample0_reg; - reg noise_sample_reg; + reg noise_sample0_reg; + reg noise_sample_reg; - reg flank0_reg; - reg flank1_reg; + reg flank0_reg; + reg flank1_reg; reg [31 : 0] cycle_ctr_reg; + reg [31 : 0] seconds_ctr_reg; + reg [31 : 0] seconds_ctr_new; + + reg [5 : 0] bit_ctr_reg; + reg [5 : 0] bit_ctr_new; + reg bit_ctr_inc; + reg bit_ctr_rst; + reg bit_ctr_we; + reg [31 : 0] entropy_reg; reg [31 : 0] entropy_new; reg entropy_we; - + + reg entropy_ready_reg; + reg entropy_ready_new; + reg [31 : 0] debug_ctr_reg; reg [31 : 0] debug_ctr_new; reg debug_ctr_we; - - reg [7 : 0] debug_reg; - reg [7 : 0] debug_new; - reg debug_we; - + reg [7 : 0] debug_reg; + reg [7 : 0] debug_new; + reg debug_we; + + reg [31 : 0] posflank_ctr_reg; + reg [31 : 0] posflank_ctr_new; + reg posflank_ctr_rst; + reg posflank_ctr_we; + + reg [31 : 0] negflank_ctr_reg; + reg [31 : 0] negflank_ctr_new; + reg negflank_ctr_rst; + reg negflank_ctr_we; + + reg [31 : 0] posflank_sample_reg; + reg [31 : 0] posflank_sample_new; + reg posflank_sample_we; + + reg [31 : 0] negflank_sample_reg; + reg [31 : 0] negflank_sample_new; + reg negflank_sample_we; + + reg [31 : 0] totflank_sample_reg; + reg [31 : 0] totflank_sample_new; + reg totflank_sample_we; + + + //---------------------------------------------------------------- + // Wires. + //---------------------------------------------------------------- + reg [31 : 0] tmp_read_data; + reg tmp_error; + + //---------------------------------------------------------------- // Concurrent connectivity for ports etc. //---------------------------------------------------------------- - assign debug = debug_reg; - - + assign entropy_ready = entropy_ready_reg; + assign entropy_data = entropy_reg; + assign debug = debug_reg; + + assign read_data = tmp_read_data; + assign error = tmp_error; + + //---------------------------------------------------------------- // reg_update //---------------------------------------------------------------- @@ -97,25 +161,42 @@ module external_avalanche_entropy( begin if (!reset_n) begin - noise_sample_reg <= 1'b0; - flank0_reg <= 1'b0; - flank1_reg <= 1'b0; - cycle_ctr_reg <= 32'h00000000; - debug_ctr_reg <= 32'h00000000; - entropy_reg <= 32'h00000000; - debug_reg <= 8'h00; + noise_sample0_reg <= 1'b0; + noise_sample_reg <= 1'b0; + flank0_reg <= 1'b0; + flank1_reg <= 1'b0; + debug_reg <= 8'h00; + entropy_ready_reg <= 1'b0; + entropy_reg <= 32'h00000000; + cycle_ctr_reg <= 32'h00000000; + seconds_ctr_reg <= 32'h00000000; + debug_ctr_reg <= 32'h00000000; + bit_ctr_reg <= 6'h00; + posflank_ctr_reg <= 32'h00000000; + negflank_ctr_reg <= 32'h00000000; + posflank_sample_reg <= 32'h00000000; + negflank_sample_reg <= 32'h00000000; + totflank_sample_reg <= 32'h00000000; end else begin noise_sample0_reg <= noise; - noise_sample_reg <= noise_sample0_reg; + noise_sample_reg <= noise_sample0_reg; + + flank0_reg <= noise_sample_reg; + flank1_reg <= flank0_reg; + + entropy_ready_reg <= entropy_ready_new; - flank0_reg <= noise_sample_reg; - flank1_reg <= flank0_reg; + cycle_ctr_reg <= cycle_ctr_reg + 1'b1; + seconds_ctr_reg <= cycle_ctr_reg + 1'b1; + debug_ctr_reg <= debug_ctr_new; + + if (bit_ctr_we) + begin + bit_ctr_reg <= bit_ctr_new; + end - cycle_ctr_reg <= cycle_ctr_reg + 1'b1; - debug_ctr_reg <= debug_ctr_new; - if (entropy_we) begin entropy_reg <= entropy_new; @@ -125,6 +206,31 @@ module external_avalanche_entropy( begin debug_reg <= debug_new; end + + if (posflank_ctr_we) + begin + posflank_ctr_reg <= posflank_ctr_new; + end + + if (negflank_ctr_we) + begin + posflank_ctr_reg <= posflank_ctr_new; + end + + if (posflank_sample_we) + begin + posflank_sample_reg <= posflank_sample_new; + end + + if (negflank_sample_we) + begin + negflank_sample_reg <= negflank_sample_new; + end + + if (totflank_sample_we) + begin + totflank_sample_reg <= totflank_sample_new; + end end end // reg_update @@ -132,23 +238,55 @@ module external_avalanche_entropy( //---------------------------------------------------------------- // entropy_collect // - // This is where we collect entropy by adding the LSB of the - // cycle counter to the entropy shift register every time - // we detect a positive flank at the noise source. + // We collect entropy by adding the LSB of the cycle counter to + // the entropy shift register every time we detect a positive + // flank in the noise source. //---------------------------------------------------------------- always @* begin : entropy_collect entropy_new = 32'h00000000; entropy_we = 1'b0; + bit_ctr_inc = 1'b0; - // Update the entropy shift register every positive flank. if ((flank0_reg) && (!flank1_reg)) begin entropy_new = {entropy_reg[30 : 0], cycle_ctr_reg[0]}; entropy_we = 1'b1; + bit_ctr_inc = 1'b1; end end // entropy_collect - + + + //---------------------------------------------------------------- + // entropy_read_logic + // + // The logic needed to handle detection that entropy has been + // read and ensure that we collect more than 32 entropy + // bits beforeproviding more entropy. + //---------------------------------------------------------------- + always @* + begin : entropy_read_logic + bit_ctr_new = 6'h00; + bit_ctr_we = 1'b0; + entropy_ready_new = 1'b0; + + if (bit_ctr_reg == 6'h20) + begin + entropy_ready_new = 1'b1; + end + + if ((bit_ctr_inc) && (bit_ctr_reg < 6'h20)) + begin + bit_ctr_new = bit_ctr_reg + 1'b1; + bit_ctr_we = 1'b1; + end + else if (entropy_read || bit_ctr_rst) + begin + bit_ctr_new = 6'h00; + bit_ctr_we = 1'b1; + end + end // entropy_read_logic + //---------------------------------------------------------------- // debug_update @@ -168,7 +306,126 @@ module external_avalanche_entropy( debug_we = 1'b1; end end // debug_update - + + + //---------------------------------------------------------------- + // flank_counters + //---------------------------------------------------------------- + always @* + begin : flank_counters + posflank_ctr_new = 32'h00000000; + posflank_ctr_we = 1'b0; + negflank_ctr_new = 32'h00000000; + negflank_ctr_we = 1'b0; + + if ((flank0_reg) && (!flank1_reg)) + begin + posflank_ctr_new = posflank_ctr_reg + 1'b1; + posflank_ctr_we = 1'b0; + end + + if ((!flank0_reg) && (flank1_reg)) + begin + negflank_ctr_new = negflank_ctr_reg + 1'b1; + negflank_ctr_we = 1'b0; + end + end // flank_counters + + + //---------------------------------------------------------------- + // stats_updates + // + // Update the statistics counters once every second. + //---------------------------------------------------------------- + always @* + begin : stats_update + seconds_ctr_new = seconds_ctr_reg + 1'b1; + posflank_sample_new = 32'h00000000; + posflank_sample_we = 1'b0; + negflank_sample_new = 32'h00000000; + negflank_sample_we = 1'b0; + totflank_sample_new = 32'h00000000; + totflank_sample_we = 1'b0; + posflank_ctr_rst = 1'b0; + negflank_ctr_rst = 1'b0; + + if (seconds_ctr_reg == SECONDS_RATE) + begin + seconds_ctr_new = 32'h00000000; + posflank_sample_new = posflank_ctr_reg; + negflank_sample_new = negflank_ctr_reg; + totflank_sample_new = posflank_ctr_reg + negflank_ctr_reg; + posflank_sample_we = 1'b1; + negflank_sample_we = 1'b1; + totflank_sample_we = 1'b1; + posflank_ctr_rst = 1'b1; + negflank_ctr_rst = 1'b1; + end + end // stats_update + + + //---------------------------------------------------------------- + // api_logic + //---------------------------------------------------------------- + always @* + begin : api_logic + tmp_read_data = 32'h00000000; + tmp_error = 1'b0; + bit_ctr_rst = 1'b1; + + if (cs) + begin + if (we) + begin + case (address) + // Write operations. + + default: + begin + tmp_error = 1; + end + endcase // case (address) + end // if (we) + + else + begin + case (address) + // Read operations. + ADDR_STATUS: + begin + tmp_read_data = {31'h00000000, entropy_ready_reg}; + end + + ADDR_ENTROPY: + begin + tmp_read_data = entropy_reg; + bit_ctr_rst = 1'b1; + end + + ADDR_POS_FLANKS: + begin + tmp_read_data = posflank_sample_reg; + end + + ADDR_NEG_FLANKS: + begin + tmp_read_data = negflank_sample_reg; + end + + ADDR_TOT_FLANKS: + begin + tmp_read_data = totflank_sample_reg; + end + + default: + begin + tmp_error = 1; + end + endcase // case (address) + end // else: !if(we) + end // if (cs) + end // api_logic + endmodule // external_avalanche_entropy //====================================================================== |