diff options
Diffstat (limited to 'rtl/src/verilog/eim_arbiter_cdc.v')
-rw-r--r-- | rtl/src/verilog/eim_arbiter_cdc.v | 253 |
1 files changed, 147 insertions, 106 deletions
diff --git a/rtl/src/verilog/eim_arbiter_cdc.v b/rtl/src/verilog/eim_arbiter_cdc.v index 6a60552..c9df62e 100644 --- a/rtl/src/verilog/eim_arbiter_cdc.v +++ b/rtl/src/verilog/eim_arbiter_cdc.v @@ -1,106 +1,147 @@ -`timescale 1ns / 1ps
-
-module eim_arbiter_cdc
- (
- eim_clk, eim_req, eim_ack, eim_din, eim_dout,
- sys_clk, sys_addr,
- sys_wren, sys_data_out,
- sys_rden, sys_data_in
- );
-
-
- input wire eim_clk; // eim clock
- input wire eim_req; // eim transaction request
- output wire eim_ack; // eim transaction acknowledge
- input wire [47: 0] eim_din; // data from cpu to fpga (write access)
- output wire [31: 0] eim_dout; // data from fpga to cpu (read access)
-
- input wire sys_clk; // user internal clock
- output wire [13: 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
-
-
- //
- // EIM_CLK -> SYS_CLK Request
- //
- wire sys_req; // request pulse in sys_clk clock domain
- wire [47: 0] sys_dout; // transaction data in sys_clk clock domain
-
- cdc_bus_pulse #
- (
- .DATA_WIDTH (48) // {write, read, addr, data}
- )
- cdc_eim_sys
- (
- .src_clk (eim_clk),
- .src_din (eim_din),
- .src_req (eim_req),
-
- .dst_clk (sys_clk),
- .dst_dout (sys_dout),
- .dst_pulse (sys_req)
- );
-
-
- //
- // Output Registers
- //
- reg [13: 0] sys_addr_reg = {14{1'bX}}; //
- reg sys_wren_reg = 1'b0; //
- reg [31: 0] sys_data_out_reg = {32{1'bX}}; //
- reg sys_rden_reg = 1'b0; //
-
- assign sys_addr = sys_addr_reg;
- assign sys_wren = sys_wren_reg;
- assign sys_data_out = sys_data_out_reg;
- assign sys_rden = sys_rden_reg;
-
-
- //
- // System (User) Clock Access Handler
- //
- always @(posedge sys_clk)
- //
- if (sys_req) begin // request detected?
- sys_wren_reg <= sys_dout[47]; // set write flag if needed
- sys_addr_reg <= sys_dout[45:32]; // set operation address
- sys_data_out_reg <= sys_dout[31: 0]; // set data to write
- sys_rden_reg <= sys_dout[46]; // set read flag if needed
- end else begin // no request active
- 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 -> EIM_CLK Acknowledge
- //
- cdc_bus_pulse #
- (
- .DATA_WIDTH (32) // {data}
- )
- cdc_sys_eim
- (
- .src_clk (sys_clk),
- .src_din (sys_data_in),
- .src_req (sys_req_dly[1]),
-
- .dst_clk (eim_clk),
- .dst_dout (eim_dout),
- .dst_pulse (eim_ack)
- );
-
-
-endmodule
+//====================================================================== +// +// eim_arbiter_cdc.v +// ----------------- +// The actual clock domain crossing handler od the EIM arbiter +// for the Cryptech Novena FPGA framework. +// +// +// Author: Pavel Shatov +// Copyright (c) 2014, 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 eim_arbiter_cdc + ( + eim_clk, eim_req, eim_ack, eim_din, eim_dout, + sys_clk, sys_addr, + sys_wren, sys_data_out, + sys_rden, sys_data_in + ); + + + input wire eim_clk; // eim clock + input wire eim_req; // eim transaction request + output wire eim_ack; // eim transaction acknowledge + input wire [47: 0] eim_din; // data from cpu to fpga (write access) + output wire [31: 0] eim_dout; // data from fpga to cpu (read access) + + input wire sys_clk; // user internal clock + output wire [13: 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 + + + // + // EIM_CLK -> SYS_CLK Request + // + wire sys_req; // request pulse in sys_clk clock domain + wire [47: 0] sys_dout; // transaction data in sys_clk clock domain + + cdc_bus_pulse # + ( + .DATA_WIDTH (48) // {write, read, addr, data} + ) + cdc_eim_sys + ( + .src_clk (eim_clk), + .src_din (eim_din), + .src_req (eim_req), + + .dst_clk (sys_clk), + .dst_dout (sys_dout), + .dst_pulse (sys_req) + ); + + + // + // Output Registers + // + reg [13: 0] sys_addr_reg = {14{1'bX}}; // + reg sys_wren_reg = 1'b0; // + reg [31: 0] sys_data_out_reg = {32{1'bX}}; // + reg sys_rden_reg = 1'b0; // + + assign sys_addr = sys_addr_reg; + assign sys_wren = sys_wren_reg; + assign sys_data_out = sys_data_out_reg; + assign sys_rden = sys_rden_reg; + + + // + // System (User) Clock Access Handler + // + always @(posedge sys_clk) + // + if (sys_req) begin // request detected? + sys_wren_reg <= sys_dout[47]; // set write flag if needed + sys_addr_reg <= sys_dout[45:32]; // set operation address + sys_data_out_reg <= sys_dout[31: 0]; // set data to write + sys_rden_reg <= sys_dout[46]; // set read flag if needed + end else begin // no request active + 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 -> EIM_CLK Acknowledge + // + cdc_bus_pulse # + ( + .DATA_WIDTH (32) // {data} + ) + cdc_sys_eim + ( + .src_clk (sys_clk), + .src_din (sys_data_in), + .src_req (sys_req_dly[1]), + + .dst_clk (eim_clk), + .dst_dout (eim_dout), + .dst_pulse (eim_ack) + ); + + +endmodule + +//====================================================================== +// EOF eim_arbiter_cdc.v +//====================================================================== |