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dinesha |
/*********************************************************************
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SDRAM Controller buswidth converter
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This file is part of the sdram controller project
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http://www.opencores.org/cores/sdr_ctrl/
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Description: SDRAM Controller Buswidth converter
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This module does write/read data transalation between
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application data to SDRAM bus width
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To Do:
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nothing
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Author(s):
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- Dinesh Annayya, dinesha@opencores.org
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Version : 0.0 - 8th Jan 2012 - Initial structure
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0.2 - 2nd Feb 2012
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Improved the command pipe structure to accept up-to 4 command of different bank.
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0.3 - 6th Feb 2012
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Bug fix on read valid generation
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Copyright (C) 2000 Authors and OPENCORES.ORG
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This source file may be used and distributed without
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restriction provided that this copyright statement is not
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removed from the file and that any derivative work contains
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the original copyright notice and the associated disclaimer.
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This source file is free software; you can redistribute it
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and/or modify it under the terms of the GNU Lesser General
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Public License as published by the Free Software Foundation;
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either version 2.1 of the License, or (at your option) any
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later version.
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This source is distributed in the hope that it will be
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useful, but WITHOUT ANY WARRANTY; without even the implied
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warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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PURPOSE. See the GNU Lesser General Public License for more
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details.
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You should have received a copy of the GNU Lesser General
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Public License along with this source; if not, download it
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from http://www.opencores.org/lgpl.shtml
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*******************************************************************/
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`include "sdrc_define.v"
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module sdrc_bs_convert (
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clk ,
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reset_n ,
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sdr_width ,
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/* Control Signal from xfr ctrl */
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x2a_rdstart ,
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x2a_wrstart ,
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x2a_rdlast ,
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x2a_wrlast ,
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x2a_rddt ,
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x2a_rdok ,
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a2x_wrdt ,
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a2x_wren_n ,
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x2a_wrnext ,
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/* Control Signal from/to to application i/f */
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app_wr_data ,
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app_wr_en_n ,
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app_wr_next ,
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app_last_wr ,
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app_rd_data ,
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app_rd_valid ,
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app_last_rd
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);
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parameter APP_AW = 30; // Application Address Width
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parameter APP_DW = 32; // Application Data Width
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parameter APP_BW = 4; // Application Byte Width
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parameter SDR_DW = 16; // SDR Data Width
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parameter SDR_BW = 2; // SDR Byte Width
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input clk ;
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input reset_n ;
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input [1:0] sdr_width ; // 2'b00 - 32 Bit SDR, 2'b01 - 16 Bit SDR, 2'b1x - 8 Bit
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/* Control Signal from xfr ctrl Read Transaction*/
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input x2a_rdstart ; // read start indication
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input x2a_rdlast ; // read last burst access
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input [SDR_DW-1:0] x2a_rddt ;
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input x2a_rdok ;
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/* Control Signal from xfr ctrl Write Transaction*/
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input x2a_wrstart ; // writ start indication
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input x2a_wrlast ; // write last transfer
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input x2a_wrnext ;
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output [SDR_DW-1:0] a2x_wrdt ;
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output [SDR_BW-1:0] a2x_wren_n ;
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// Application Write Transaction
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input [APP_DW-1:0] app_wr_data ;
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input [APP_BW-1:0] app_wr_en_n ;
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output app_wr_next ;
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output app_last_wr ; // Indicate last Write Transfer for a given burst size
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// Application Read Transaction
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output [APP_DW-1:0] app_rd_data ;
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output app_rd_valid ;
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output app_last_rd ; // Indicate last Read Transfer for a given burst size
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//----------------------------------------------
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// Local Decleration
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// ----------------------------------------
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reg [APP_DW-1:0] app_rd_data ;
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reg app_rd_valid ;
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reg [SDR_DW-1:0] a2x_wrdt ;
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reg [SDR_BW-1:0] a2x_wren_n ;
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reg app_wr_next ;
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reg [23:0] saved_rd_data ;
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reg [1:0] rd_xfr_count ;
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reg [1:0] wr_xfr_count ;
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assign app_last_wr = x2a_wrlast;
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assign app_last_rd = x2a_rdlast;
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always @(*) begin
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if(sdr_width == 2'b00) // 32 Bit SDR Mode
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begin
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a2x_wrdt = app_wr_data;
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a2x_wren_n = app_wr_en_n;
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app_wr_next = x2a_wrnext;
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app_rd_data = x2a_rddt;
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app_rd_valid = x2a_rdok;
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end
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else if(sdr_width == 2'b01) // 16 Bit SDR Mode
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begin
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// Changed the address and length to match the 16 bit SDR Mode
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app_wr_next = (x2a_wrnext & wr_xfr_count[0]);
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app_rd_valid = (x2a_rdok & rd_xfr_count[0]);
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if(wr_xfr_count[0] == 1'b1)
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begin
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a2x_wren_n = app_wr_en_n[3:2];
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a2x_wrdt = app_wr_data[31:16];
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end
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else
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begin
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a2x_wren_n = app_wr_en_n[1:0];
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a2x_wrdt = app_wr_data[15:0];
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end
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app_rd_data = {x2a_rddt,saved_rd_data[15:0]};
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end else // 8 Bit SDR Mode
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begin
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// Changed the address and length to match the 16 bit SDR Mode
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app_wr_next = (x2a_wrnext & (wr_xfr_count[1:0]== 2'b11));
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app_rd_valid = (x2a_rdok & (rd_xfr_count[1:0]== 2'b11));
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if(wr_xfr_count[1:0] == 2'b11)
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begin
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a2x_wren_n = app_wr_en_n[3];
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a2x_wrdt = app_wr_data[31:24];
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end
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else if(wr_xfr_count[1:0] == 2'b10)
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begin
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a2x_wren_n = app_wr_en_n[2];
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a2x_wrdt = app_wr_data[23:16];
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end
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else if(wr_xfr_count[1:0] == 2'b01)
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begin
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a2x_wren_n = app_wr_en_n[1];
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a2x_wrdt = app_wr_data[15:8];
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end
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else begin
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a2x_wren_n = app_wr_en_n[0];
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a2x_wrdt = app_wr_data[7:0];
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end
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app_rd_data = {x2a_rddt,saved_rd_data[23:0]};
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end
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end
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always @(posedge clk)
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begin
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if(!reset_n)
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begin
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rd_xfr_count <= 8'b0;
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wr_xfr_count <= 8'b0;
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saved_rd_data <= 24'h0;
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end
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else begin
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// During Write Phase
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if(x2a_wrlast) begin
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wr_xfr_count <= 0;
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end
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else if(x2a_wrnext) begin
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wr_xfr_count <= wr_xfr_count + 1'b1;
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end
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// During Read Phase
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if(x2a_rdlast) begin
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rd_xfr_count <= 0;
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end
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else if(x2a_rdok) begin
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rd_xfr_count <= rd_xfr_count + 1'b1;
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end
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// Save Previous Data
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if(x2a_rdok) begin
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if(sdr_width == 2'b01) // 16 Bit SDR Mode
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saved_rd_data[15:0] <= x2a_rddt;
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else begin// 8 bit SDR Mode -
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if(rd_xfr_count[1:0] == 2'b00) saved_rd_data[7:0] <= x2a_rddt[7:0];
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else if(rd_xfr_count[1:0] == 2'b01) saved_rd_data[15:8] <= x2a_rddt[7:0];
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else if(rd_xfr_count[1:0] == 2'b10) saved_rd_data[23:16] <= x2a_rddt[7:0];
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end
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end
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end
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end
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endmodule // sdr_bs_convert
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