[Cryptech-Commits] [core/comm/fmc] 01/03: Removed now unnecessary CDC modules.
git at cryptech.is
git at cryptech.is
Thu Jul 5 21:21:39 UTC 2018
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meisterpaul1 at yandex.ru pushed a commit to branch fmc_clk
in repository core/comm/fmc.
commit 0bcccfe4c8a618f2826f70a4d0561808239052bf
Author: Pavel V. Shatov (Meister) <meisterpaul1 at yandex.ru>
AuthorDate: Thu Jul 5 14:25:10 2018 +0300
Removed now unnecessary CDC modules.
---
src/rtl/cdc_bus_pulse.v | 145 ----------------------------------------------
src/rtl/fmc_arbiter_cdc.v | 145 ----------------------------------------------
2 files changed, 290 deletions(-)
diff --git a/src/rtl/cdc_bus_pulse.v b/src/rtl/cdc_bus_pulse.v
deleted file mode 100644
index cc2d8db..0000000
--- a/src/rtl/cdc_bus_pulse.v
+++ /dev/null
@@ -1,145 +0,0 @@
-//======================================================================
-//
-// cdc_bus_pulse.v
-// ---------------
-// Clock Domain Crossing handler for the Cryptech Novena
-// FPGA framework design.
-//
-// This module is based on design suggested on page 27 of the
-// paper 'Clock Domain Crossing (CDC) Design & Verification Techniques
-// Using SystemVerilog' by Clifford E. Cummings (Sunburst Design, Inc.)
-//
-//
-// Author: Pavel Shatov
-// Copyright (c) 2015, 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 cdc_bus_pulse
- #(parameter DATA_WIDTH = 32) // width of data bus
- (
- input wire src_clk, // source domain clock
- input wire [DATA_WIDTH-1:0] src_din, // data from source clock domain
- input wire src_req, // start transfer pulse from source clock domain
-
- input wire dst_clk, // destination domain clock
- output wire [DATA_WIDTH-1:0] dst_dout, // data to destination clock domain
- output wire dst_pulse // transfer done pulse to destination clock domain
- );
-
- //
- // Source Side Registers
- //
- reg src_ff = 1'b0; // transfer request flag
- reg [DATA_WIDTH-1:0] src_latch = {DATA_WIDTH{1'bX}}; // source data buffer
-
-
- //
- // Source Request Handler
- //
- always @(posedge src_clk)
- //
- if (src_req) begin // transfer request pulse?
- src_ff <= ~src_ff; // toggle transfer request flag...
- src_latch <= src_din; // ... and capture data in source buffer
- end
-
-
- //
- // Source -> Destination Flag Sync Logic
- //
-
- /* ISE may decide to infer SRL here, so we explicitly instantiate slice registers. */
-
- wire flag_sync_first; // first FF output
- wire flag_sync_second; // second FF output
- wire flag_sync_third; // third FF output
- wire flag_sync_pulse; // flag toggle detector output
-
- FDCE ff_sync_first
- (
- .C(dst_clk),
- .D(src_ff), // capture flag from another clock domain
- .Q(flag_sync_first), // metastability can occur here
- .CLR(1'b0),
- .CE(1'b1)
- );
- FDCE ff_sync_second
- (
- .C(dst_clk),
- .D(flag_sync_first), // synchronize captured flag to remove metastability
- .Q(flag_sync_second), // and pass it to another flip-flop
- .CLR(1'b0),
- .CE(1'b1)
- );
- FDCE ff_sync_third
- (
- .C(dst_clk),
- .D(flag_sync_second), // delay synchronized flag in another flip-flip, because we need
- .Q(flag_sync_third), // two synchronized flag values (current and delayed) to detect its change
- .CLR(1'b0),
- .CE(1'b1)
- );
-
- // when delayed flag value differs from its current value, it was changed
- // by the source side, so there must have been a transfer request
- assign flag_sync_pulse = flag_sync_second ^ flag_sync_third;
-
-
- //
- // Destination Side Registers
- //
- reg dst_pulse_reg = 1'b0; // transfer done flag
- reg [DATA_WIDTH-1:0] dst_latch = {DATA_WIDTH{1'bX}}; // destination data buffer
-
- assign dst_pulse = dst_pulse_reg;
- assign dst_dout = dst_latch;
-
- //
- // Destination Request Handler
- //
- always @(posedge dst_clk) begin
- //
- dst_pulse_reg <= flag_sync_pulse; // generate pulse if flag change was detected
- //
- if (flag_sync_pulse)
- dst_latch <= src_latch;
- /* By the time destination side receives synchronized flag
- * value, data should be stable, we can safely capture and store
- * it in the destination buffer.
- */
-
- end
-
-
-endmodule
-
-//======================================================================
-// EOF cdc_bus_pulse.v
-//======================================================================
diff --git a/src/rtl/fmc_arbiter_cdc.v b/src/rtl/fmc_arbiter_cdc.v
deleted file mode 100644
index 63e65b5..0000000
--- a/src/rtl/fmc_arbiter_cdc.v
+++ /dev/null
@@ -1,145 +0,0 @@
-//======================================================================
-//
-// fmc_arbiter_cdc.v
-// -----------------
-// The actual clock domain crossing handler of the FMC arbiter
-// for the Cryptech Novena FPGA framework.
-//
-//
-// Author: Pavel Shatov
-// Copyright (c) 2015, 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 fmc_arbiter_cdc #
- (
- parameter NUM_ADDR_BITS = 22
- )
- (
- input wire fmc_clk, // fmc clock
- input wire fmc_req, // fmc transaction request
- output wire fmc_ack, // fmc transaction acknowledge
- input wire [NUM_ADDR_BITS+32+2-1: 0] fmc_din, // data from cpu to fpga (write access)
- output wire [31: 0] fmc_dout, // data from fpga to cpu (read access)
-
- input wire sys_clk, // user internal clock
- output wire [NUM_ADDR_BITS-1: 0] sys_addr, // user access address
- output wire sys_wren, // user write flag
- output wire [31: 0] sys_data_out, // user write data
- output wire sys_rden, // user read flag
- input wire [31: 0] sys_data_in // user read data
- );
-
-
- //
- // FMC_CLK -> SYS_CLK Request
- //
- wire sys_req; // request pulse in sys_clk clock domain
- wire [NUM_ADDR_BITS+32+2-1: 0] sys_dout; // transaction data in sys_clk clock domain
-
- cdc_bus_pulse #
- (
- .DATA_WIDTH(NUM_ADDR_BITS+32+2) // {write, read, addr, data}
- )
- cdc_fmc_sys
- (
- .src_clk(fmc_clk),
- .src_din(fmc_din),
- .src_req(fmc_req),
-
- .dst_clk(sys_clk),
- .dst_dout(sys_dout),
- .dst_pulse(sys_req)
- );
-
-
- //
- // Output Registers
- //
- reg sys_wren_reg = 1'b0;
- reg sys_rden_reg = 1'b0;
- reg [NUM_ADDR_BITS-1: 0] sys_addr_reg = {NUM_ADDR_BITS{1'bX}};
- reg [31: 0] sys_data_out_reg = {32{1'bX}};
-
- assign sys_wren = sys_wren_reg;
- assign sys_rden = sys_rden_reg;
- assign sys_addr = sys_addr_reg;
- assign sys_data_out = sys_data_out_reg;
-
-
- //
- // System (User) Clock Access Handler
- //
- always @(posedge sys_clk)
- //
- if (sys_req) // request detected?
- begin
- sys_wren_reg <= sys_dout[32+NUM_ADDR_BITS+1]; // set write flag if needed
- sys_rden_reg <= sys_dout[32+NUM_ADDR_BITS+0]; // set read flag if needed
- sys_addr_reg <= sys_dout[32+NUM_ADDR_BITS-1:32]; // set operation address
- sys_data_out_reg <= sys_dout[31: 0]; // set data to write
- end
- else // no request active
- begin
- sys_wren_reg <= 1'b0; // clear write flag
- sys_rden_reg <= 1'b0; // clear read flag
- end
-
-
- //
- // System Request 2-cycle delay to compensate registered mux delay in user-side logic
- //
- reg [ 1: 0] sys_req_dly = 2'b00;
-
- always @(posedge sys_clk)
- sys_req_dly <= {sys_req_dly[0], sys_req};
-
- //
- // SYS_CLK -> FMC_CLK Acknowledge
- //
- cdc_bus_pulse #
- (
- .DATA_WIDTH(32)
- )
- cdc_sys_fmc
- (
- .src_clk(sys_clk),
- .src_din(sys_data_in),
- .src_req(sys_req_dly[1]),
-
- .dst_clk(fmc_clk),
- .dst_dout(fmc_dout),
- .dst_pulse(fmc_ack)
- );
-
-endmodule
-
-//======================================================================
-// EOF fmc_arbiter_cdc.v
-//======================================================================
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