| ////////////////////////////////////////////////////////////////////////////// |
| // SPDX-FileCopyrightText: 2021 , Dinesh Annayya |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| // SPDX-License-Identifier: Apache-2.0 |
| // SPDX-FileContributor: Created by Dinesh Annayya <dinesha@opencores.org> |
| // |
| ////////////////////////////////////////////////////////////////////// |
| //// //// |
| //// Async Wishbone Interface //// |
| //// //// |
| //// This file is part of the YIFive cores project //// |
| //// http://www.opencores.org/cores/yifive/ //// |
| //// //// |
| //// Description //// |
| //// This block does async Wishbone from one clock to other //// |
| //// clock domain |
| //// //// |
| //// To Do: //// |
| //// nothing //// |
| //// //// |
| //// Author(s): //// |
| //// - Dinesh Annayya, dinesha@opencores.org //// |
| //// //// |
| //// Revision : //// |
| //// 0.1 - 25th Feb 2021, Dinesh A //// |
| //// initial version //// |
| //// 0.2 - 28th Feb 2021, Dinesh A //// |
| //// reduced the response FIFO path depth to 2 as //// |
| //// return path used by only read logic and read is //// |
| //// blocking request and expect only one location will //// |
| //// be used //// |
| ////////////////////////////////////////////////////////////////////// |
| //// //// |
| //// Copyright (C) 2000 Authors and OPENCORES.ORG //// |
| //// //// |
| //// This source file may be used and distributed without //// |
| //// restriction provided that this copyright statement is not //// |
| //// removed from the file and that any derivative work contains //// |
| //// the original copyright notice and the associated disclaimer. //// |
| //// //// |
| //// This source file is free software; you can redistribute it //// |
| //// and/or modify it under the terms of the GNU Lesser General //// |
| //// Public License as published by the Free Software Foundation; //// |
| //// either version 2.1 of the License, or (at your option) any //// |
| //// later version. //// |
| //// //// |
| //// This source is distributed in the hope that it will be //// |
| //// useful, but WITHOUT ANY WARRANTY; without even the implied //// |
| //// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR //// |
| //// PURPOSE. See the GNU Lesser General Public License for more //// |
| //// details. //// |
| //// //// |
| //// You should have received a copy of the GNU Lesser General //// |
| //// Public License along with this source; if not, download it //// |
| //// from http://www.opencores.org/lgpl.shtml //// |
| //// //// |
| ////////////////////////////////////////////////////////////////////// |
| |
| module async_wb |
| #(parameter AW = 32, |
| parameter BW = 4, |
| parameter DW = 32) |
| ( |
| |
| // Master Port |
| input logic wbm_rst_n , // Regular Reset signal |
| input logic wbm_clk_i , // System clock |
| input logic wbm_cyc_i , // strobe/request |
| input logic wbm_stb_i , // strobe/request |
| input logic [AW-1:0] wbm_adr_i , // address |
| input logic wbm_we_i , // write |
| input logic [DW-1:0] wbm_dat_i , // data output |
| input logic [BW-1:0] wbm_sel_i , // byte enable |
| output logic [DW-1:0] wbm_dat_o , // data input |
| output logic wbm_ack_o , // acknowlegement |
| output logic wbm_err_o , // error |
| |
| // Slave Port |
| input logic wbs_rst_n , // Regular Reset signal |
| input logic wbs_clk_i , // System clock |
| output logic wbs_cyc_o , // strobe/request |
| output logic wbs_stb_o , // strobe/request |
| output logic [AW-1:0] wbs_adr_o , // address |
| output logic wbs_we_o , // write |
| output logic [DW-1:0] wbs_dat_o , // data output |
| output logic [BW-1:0] wbs_sel_o , // byte enable |
| input logic [DW-1:0] wbs_dat_i , // data input |
| input logic wbs_ack_i , // acknowlegement |
| input logic wbs_err_i // error |
| |
| ); |
| |
| |
| |
| parameter CFW = AW+DW+BW+1 ; // COMMAND FIFO WIDTH |
| |
| //------------------------------------------------- |
| // Master Interface |
| // ------------------------------------------------- |
| logic PendingRd ; // Pending Read Transaction |
| logic m_cmd_wr_en ; |
| logic [CFW-1:0] m_cmd_wr_data ; |
| logic m_cmd_wr_full ; |
| logic m_cmd_wr_afull ; |
| |
| logic m_resp_rd_empty ; |
| logic m_resp_rd_aempty ; |
| logic m_resp_rd_en ; |
| logic [DW:0] m_resp_rd_data ; |
| |
| // Master Write Interface |
| |
| |
| assign m_cmd_wr_en = (!PendingRd) && wbm_stb_i && !m_cmd_wr_full && !m_cmd_wr_afull; |
| |
| assign m_cmd_wr_data = {wbm_adr_i,wbm_we_i,wbm_dat_i,wbm_sel_i}; |
| |
| always@(negedge wbm_rst_n or posedge wbm_clk_i) |
| begin |
| if(wbm_rst_n == 0) begin |
| PendingRd <= 1'b0; |
| end else begin |
| if((!PendingRd) && wbm_stb_i && (!wbm_we_i) && m_cmd_wr_en) begin |
| PendingRd <= 1'b1; |
| end else if(PendingRd && wbm_stb_i && (!wbm_we_i) && wbm_ack_o) begin |
| PendingRd <= 1'b0; |
| end |
| end |
| end |
| |
| |
| // Master Read Interface |
| // For Write is feed through, if there is space in fifo the ack |
| // For Read, Wait for Response Path FIFO status |
| assign wbm_ack_o = (wbm_stb_i && wbm_we_i) ? m_cmd_wr_en : // Write Logic |
| (wbm_stb_i && (!wbm_we_i)) ? !m_resp_rd_empty : 1'b0; // Read Logic |
| |
| assign m_resp_rd_en = !m_resp_rd_empty; |
| assign wbm_dat_o = m_resp_rd_data[DW-1:0]; |
| assign wbm_err_o = m_resp_rd_data[DW]; |
| |
| |
| //------------------------------ |
| // Slave Interface |
| //------------------------------- |
| |
| logic [CFW-1:0] s_cmd_rd_data ; |
| logic s_cmd_rd_empty ; |
| logic s_cmd_rd_aempty ; |
| logic s_cmd_rd_en ; |
| logic s_resp_wr_en ; |
| logic [DW:0] s_resp_wr_data ; |
| logic s_resp_wr_full ; |
| logic s_resp_wr_afull ; |
| logic wbs_ack_f ; |
| |
| |
| always@(negedge wbs_rst_n or posedge wbs_clk_i) |
| begin |
| if(wbs_rst_n == 0) begin |
| wbs_ack_f <= 1'b0; |
| end else begin |
| wbs_ack_f <= wbs_ack_i; |
| end |
| end |
| |
| |
| // Read Interface |
| assign {wbs_adr_o,wbs_we_o,wbs_dat_o,wbs_sel_o} = (s_cmd_rd_empty) ? '0: s_cmd_rd_data; |
| // All the downstream logic expect Stobe is getting de-asserted |
| // atleast for 1 cycle after ack is generated |
| assign wbs_stb_o = (wbs_ack_f) ? 1'b0 : (s_cmd_rd_empty) ? 1'b0: 1'b1; |
| assign wbs_cyc_o = (wbs_ack_f) ? 1'b0 : (s_cmd_rd_empty) ? 1'b0: 1'b1; |
| |
| assign s_cmd_rd_en = wbs_ack_i; |
| |
| // Write Interface |
| // response send only for read logic |
| assign s_resp_wr_en = wbs_stb_o & (!wbs_we_o) & wbs_ack_i & !s_resp_wr_full; |
| assign s_resp_wr_data = {wbs_err_i,wbs_dat_i}; |
| |
| async_fifo #(.W(CFW), .DP(4), .WR_FAST(1), .RD_FAST(1)) u_cmd_if ( |
| // Sync w.r.t WR clock |
| .wr_clk (wbm_clk_i ), |
| .wr_reset_n (wbm_rst_n ), |
| .wr_en (m_cmd_wr_en ), |
| .wr_data (m_cmd_wr_data ), |
| .full (m_cmd_wr_full ), |
| .afull (m_cmd_wr_afull ), |
| |
| // Sync w.r.t RD Clock |
| .rd_clk (wbs_clk_i ), |
| .rd_reset_n (wbs_rst_n ), |
| .rd_en (s_cmd_rd_en ), |
| .empty (s_cmd_rd_empty ), // sync'ed to rd_clk |
| .aempty (s_cmd_rd_aempty ), // sync'ed to rd_clk |
| .rd_data (s_cmd_rd_data ) |
| ); |
| |
| |
| // Response used only read path, read is blocking access, expect |
| // only one location used in return path - reduced the depth to 2 |
| async_fifo #(.W(DW+1), .DP(2), .WR_FAST(1), .RD_FAST(0)) u_resp_if ( |
| // Sync w.r.t WR clock |
| .wr_clk (wbs_clk_i ), |
| .wr_reset_n (wbs_rst_n ), |
| .wr_en (s_resp_wr_en ), |
| .wr_data (s_resp_wr_data ), |
| .full (s_resp_wr_full ), |
| .afull (s_resp_wr_afull ), |
| |
| // Sync w.r.t RD Clock |
| .rd_clk (wbm_clk_i ), |
| .rd_reset_n (wbm_rst_n ), |
| .rd_en (m_resp_rd_en ), |
| .empty (m_resp_rd_empty ), // sync'ed to rd_clk |
| .aempty (m_resp_rd_aempty ), // sync'ed to rd_clk |
| .rd_data (m_resp_rd_data ) |
| ); |
| |
| |
| |
| endmodule |
