| /********************************************************************* |
| |
| This file is part of the sdram controller project |
| http://www.opencores.org/cores/sdr_ctrl/ |
| |
| Description: WISHBONE to SDRAM Controller Bus Transalator |
| 1. This module translate the WISHBONE protocol to custom sdram controller i/f |
| 2. Also Handle the clock domain change from Application layer to Sdram layer |
| |
| To Do: |
| nothing |
| |
| Author(s): Dinesh Annayya, dinesha@opencores.org |
| Version : 0.0 - Initial Release |
| 0.1 - 2nd Feb 2012 |
| Async Fifo towards the application layer is selected |
| with Registered Full Generation |
| 0.2 - 2nd Feb 2012 |
| Pending Read generation bug fix done to handle backto back write |
| followed by read request |
| |
| 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 wb2sdrc ( |
| // WB bus |
| wb_rst_n , |
| wb_clk_i , |
| |
| wb_stb_i , |
| wb_ack_o , |
| wb_addr_i , |
| wb_we_i , |
| wb_dat_i , |
| wb_sel_i , |
| wb_dat_o , |
| wb_cyc_i , |
| |
| |
| //SDRAM Controller Hand-Shake Signal |
| sdram_clk , |
| sdram_resetn , |
| sdr_req , |
| sdr_req_addr , |
| sdr_req_len , |
| sdr_req_wr_n , |
| sdr_req_ack , |
| sdr_busy_n , |
| sdr_wr_en_n , |
| sdr_wr_next , |
| sdr_rd_valid , |
| sdr_last_rd , |
| sdr_wr_data , |
| sdr_rd_data |
| |
| ); |
| |
| parameter dw = 32; // data width |
| parameter tw = 8; // tag id width |
| parameter bl = 9; // burst_lenght_width |
| parameter APP_AW = 26; // Application Address Width |
| //-------------------------------------- |
| // Wish Bone Interface |
| // ------------------------------------- |
| input wb_rst_n ; |
| input wb_clk_i ; |
| |
| input wb_stb_i ; |
| output wb_ack_o ; |
| input [APP_AW-1:0] wb_addr_i ; |
| input wb_we_i ; // 1 - Write , 0 - Read |
| input [dw-1:0] wb_dat_i ; |
| input [dw/8-1:0] wb_sel_i ; // Byte enable |
| output [dw-1:0] wb_dat_o ; |
| input wb_cyc_i ; |
| /*************************************************** |
| The Cycle Type Idenfier [CTI_IO()] Address Tag provides |
| additional information about the current cycle. |
| The MASTER sends this information to the SLAVE. The SLAVE can use this |
| information to prepare the response for the next cycle. |
| Table 4-2 Cycle Type Identifiers |
| CTI_O(2:0) Description |
| 000 Classic cycle. |
| 001 Constant address burst cycle |
| 010 Incrementing burst cycle |
| 011 Reserved |
| 100 Reserved |
| 101 Reserved |
| 110 Reserved |
| 111 End-of-Burst |
| ****************************************************/ |
| //-------------------------------------------- |
| // SDRAM controller Interface |
| //-------------------------------------------- |
| input sdram_clk ; // sdram clock |
| input sdram_resetn ; // sdram reset |
| output sdr_req ; // SDRAM request |
| output [APP_AW-1:0] sdr_req_addr ; // SDRAM Request Address |
| output [bl-1:0] sdr_req_len ; |
| output sdr_req_wr_n ; // 0 - Write, 1 -> Read |
| input sdr_req_ack ; // SDRAM request Accepted |
| input sdr_busy_n ; // 0 -> sdr busy |
| output [dw/8-1:0] sdr_wr_en_n ; // Active low sdr byte-wise write data valid |
| input sdr_wr_next ; // Ready to accept the next write |
| input sdr_rd_valid ; // sdr read valid |
| input sdr_last_rd ; // Indicate last Read of Burst Transfer |
| output [dw-1:0] sdr_wr_data ; // sdr write data |
| input [dw-1:0] sdr_rd_data ; // sdr read data |
| |
| //---------------------------------------------------- |
| // Wire Decleration |
| // --------------------------------------------------- |
| wire cmdfifo_full ; |
| wire cmdfifo_empty ; |
| wire wrdatafifo_full ; |
| wire wrdatafifo_empty ; |
| wire tagfifo_full ; |
| wire tagfifo_empty ; |
| wire rddatafifo_empty ; |
| wire rddatafifo_full ; |
| |
| reg pending_read ; |
| |
| |
| //----------------------------------------------------------------------------- |
| // Ack Generaltion Logic |
| // If Write Request - Acknowledge if the command and write FIFO are not full |
| // If Read Request - Generate the Acknowledgment once read fifo has data |
| // available |
| //----------------------------------------------------------------------------- |
| |
| assign wb_ack_o = (wb_stb_i && wb_cyc_i && wb_we_i) ? // Write Phase |
| ((!cmdfifo_full) && (!wrdatafifo_full)) : |
| (wb_stb_i && wb_cyc_i && !wb_we_i) ? // Read Phase |
| !rddatafifo_empty : 1'b0; |
| |
| //--------------------------------------------------------------------------- |
| // Command FIFO Write Generation |
| // If Write Request - Generate write, when Write fifo and command fifo is |
| // not full |
| // If Read Request - Generate write, when command fifo not full and there |
| // is no pending read request. |
| //--------------------------------------------------------------------------- |
| wire cmdfifo_wr = (wb_stb_i && wb_cyc_i && wb_we_i && (!cmdfifo_full) ) ? wb_ack_o : |
| (wb_stb_i && wb_cyc_i && !wb_we_i && (!cmdfifo_full)) ? !pending_read: 1'b0 ; |
| |
| //--------------------------------------------------------------------------- |
| // command fifo read generation |
| // Command FIFo read will be generated, whenever SDRAM Controller |
| // Acknowldge the Request |
| //---------------------------------------------------------------------------- |
| |
| wire cmdfifo_rd = sdr_req_ack; |
| |
| //--------------------------------------------------------------------------- |
| // Application layer request is generated towards the controller, whenever |
| // Command FIFO is not full |
| // -------------------------------------------------------------------------- |
| assign sdr_req = !cmdfifo_empty; |
| |
| //---------------------------------------------------------------------------- |
| // Since Burst length is not known at the start of the Burst, It's assumed as |
| // Single Cycle Burst. We need to improvise this ... |
| // -------------------------------------------------------------------------- |
| wire [bl-1:0] burst_length = 1; // 0 Mean 1 Transfer |
| |
| //----------------------------------------------------------------------------- |
| // In Wish Bone Spec, For Read Request has to be acked along with data. |
| // We need to identify the pending read request. |
| // Once we accept the read request, we should not accept one more read |
| // request, untill we have transmitted the read data. |
| // Pending Read will |
| // set - with Read Request |
| // reset - with Read Request + Ack |
| // ---------------------------------------------------------------------------- |
| always @(negedge wb_rst_n or posedge wb_clk_i) begin |
| if(!wb_rst_n) begin |
| pending_read <= 1'b0; |
| end else begin |
| //pending_read <= wb_stb_i & wb_cyc_i & !wb_we_i & !wb_ack_o; |
| pending_read <= (cmdfifo_wr && !wb_we_i) ? 1'b1: |
| (wb_stb_i & wb_cyc_i & !wb_we_i & wb_ack_o) ? 1'b0: pending_read; |
| end |
| end |
| |
| //--------------------------------------------------------------------- |
| // Async Command FIFO. This block handle the clock domain change from |
| // Application layer to SDRAM Controller |
| // ------------------------------------------------------------------ |
| // Address + Burst Length + W/R Request |
| async_fifo #(.W(APP_AW+bl+1),.DP(4),.WR_FAST(1'b0), .RD_FAST(1'b0)) u_cmdfifo ( |
| // Write Path Sys CLock Domain |
| .wr_clk (wb_clk_i ), |
| .wr_reset_n (wb_rst_n ), |
| .wr_en (cmdfifo_wr ), |
| .wr_data ({burst_length, |
| !wb_we_i, |
| wb_addr_i} ), |
| .afull ( ), |
| .full (cmdfifo_full ), |
| |
| // Read Path, SDRAM clock domain |
| .rd_clk (sdram_clk ), |
| .rd_reset_n (sdram_resetn ), |
| .aempty ( ), |
| .empty (cmdfifo_empty ), |
| .rd_en (cmdfifo_rd ), |
| .rd_data ({sdr_req_len, |
| sdr_req_wr_n, |
| sdr_req_addr} ) |
| ); |
| |
| // synopsys translate_off |
| always @(posedge wb_clk_i) begin |
| if (cmdfifo_full == 1'b1 && cmdfifo_wr == 1'b1) begin |
| $display("ERROR:%m COMMAND FIFO WRITE OVERFLOW"); |
| end |
| end |
| // synopsys translate_on |
| // synopsys translate_off |
| always @(posedge sdram_clk) begin |
| if (cmdfifo_empty == 1'b1 && cmdfifo_rd == 1'b1) begin |
| $display("ERROR:%m COMMAND FIFO READ OVERFLOW"); |
| end |
| end |
| // synopsys translate_on |
| |
| //--------------------------------------------------------------------- |
| // Write Data FIFO Write Generation, when ever Acked + Write Request |
| // Note: Ack signal generation already taking account of FIFO full condition |
| // --------------------------------------------------------------------- |
| |
| wire wrdatafifo_wr = wb_ack_o & wb_we_i ; |
| |
| //------------------------------------------------------------------------ |
| // Write Data FIFO Read Generation, When ever Next Write request generated |
| // from SDRAM Controller |
| // ------------------------------------------------------------------------ |
| wire wrdatafifo_rd = sdr_wr_next; |
| |
| |
| //------------------------------------------------------------------------ |
| // Async Write Data FIFO |
| // This block handle the clock domain change over + Write Data + Byte mask |
| // From Application layer to SDRAM controller layer |
| //------------------------------------------------------------------------ |
| |
| // Write DATA + Data Mask FIFO |
| async_fifo #(.W(dw+(dw/8)), .DP(8), .WR_FAST(1'b0), .RD_FAST(1'b1)) u_wrdatafifo ( |
| // Write Path , System clock domain |
| .wr_clk (wb_clk_i ), |
| .wr_reset_n (wb_rst_n ), |
| .wr_en (wrdatafifo_wr ), |
| .wr_data ({~wb_sel_i, |
| wb_dat_i} ), |
| .afull ( ), |
| .full (wrdatafifo_full ), |
| |
| |
| // Read Path , SDRAM clock domain |
| .rd_clk (sdram_clk ), |
| .rd_reset_n (sdram_resetn ), |
| .aempty ( ), |
| .empty (wrdatafifo_empty ), |
| .rd_en (wrdatafifo_rd ), |
| .rd_data ({sdr_wr_en_n, |
| sdr_wr_data} ) |
| ); |
| // synopsys translate_off |
| always @(posedge wb_clk_i) begin |
| if (wrdatafifo_full == 1'b1 && wrdatafifo_wr == 1'b1) begin |
| $display("ERROR:%m WRITE DATA FIFO WRITE OVERFLOW"); |
| end |
| end |
| |
| always @(posedge sdram_clk) begin |
| if (wrdatafifo_empty == 1'b1 && wrdatafifo_rd == 1'b1) begin |
| $display("ERROR:%m WRITE DATA FIFO READ OVERFLOW"); |
| end |
| end |
| // synopsys translate_on |
| |
| // ------------------------------------------------------------------- |
| // READ DATA FIFO |
| // ------------------------------------------------------------------ |
| wire rd_eop; // last read indication |
| |
| // Read FIFO write generation, when ever SDRAM controller issues the read |
| // valid signal |
| wire rddatafifo_wr = sdr_rd_valid; |
| |
| // Read FIFO read generation, when ever ack is generated along with read |
| // request. |
| // Note: Ack generation is already accounted the write FIFO Not Empty |
| // condition |
| wire rddatafifo_rd = wb_ack_o & !wb_we_i; |
| |
| //------------------------------------------------------------------------- |
| // Async Read FIFO |
| // This block handles the clock domain change over + Read data from SDRAM |
| // controller to Application layer. |
| // Note: |
| // 1. READ DATA FIFO depth is kept small, assuming that Sys-CLock > SDRAM Clock |
| // READ DATA + EOP |
| // 2. EOP indicate, last transfer of Burst Read Access. use-full for future |
| // Tag handling per burst |
| // |
| // ------------------------------------------------------------------------ |
| async_fifo #(.W(dw+1), .DP(4), .WR_FAST(1'b0), .RD_FAST(1'b1) ) u_rddatafifo ( |
| // Write Path , SDRAM clock domain |
| .wr_clk (sdram_clk ), |
| .wr_reset_n (sdram_resetn ), |
| .wr_en (rddatafifo_wr ), |
| .wr_data ({sdr_last_rd, |
| sdr_rd_data} ), |
| .afull ( ), |
| .full (rddatafifo_full ), |
| |
| |
| // Read Path , SYS clock domain |
| .rd_clk (wb_clk_i ), |
| .rd_reset_n (wb_rst_n ), |
| .empty (rddatafifo_empty ), |
| .aempty ( ), |
| .rd_en (rddatafifo_rd ), |
| .rd_data ({rd_eop, |
| wb_dat_o} ) |
| ); |
| |
| // synopsys translate_off |
| always @(posedge sdram_clk) begin |
| if (rddatafifo_full == 1'b1 && rddatafifo_wr == 1'b1) begin |
| $display("ERROR:%m READ DATA FIFO WRITE OVERFLOW"); |
| end |
| end |
| |
| always @(posedge wb_clk_i) begin |
| if (rddatafifo_empty == 1'b1 && rddatafifo_rd == 1'b1) begin |
| $display("ERROR:%m READ DATA FIFO READ OVERFLOW"); |
| end |
| end |
| // synopsys translate_on |
| |
| |
| endmodule |
