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/*********************************************************************

  SDRAM Controller Bank Controller

  This file is part of the sdram controller project

  http://www.opencores.org/cores/sdr_ctrl/

  Description:

    This module takes requests from sdrc_req_gen, checks for page hit/miss and

    issues precharge/activate commands and then passes the request to sdrc_xfr_ctl.

  To Do:

    nothing

  Author(s):

      - Dinesh Annayya, dinesha@opencores.org

  Version  :  1.0  - 8th Jan 2012

 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

*******************************************************************/

`include "sdrc_define.v"

module sdrc_bank_ctl (clk,

                     reset_n,

                     a2b_req_depth,  // Number of requests we can buffer

                     /* Req from req_gen */

                     r2b_req,      // request

                     r2b_req_id,   // ID

                     r2b_start,    // First chunk of burst

                     r2b_last,     // Last chunk of burst

                     r2b_wrap,

                     r2b_ba,       // bank address

                     r2b_raddr,    // row address

                     r2b_caddr,    // col address

                     r2b_len,      // length

                     r2b_write,    // write request

                     b2r_arb_ok,   // OK to arbitrate for next xfr

                     b2r_ack,

                     /* Transfer request to xfr_ctl */

                     b2x_idle,     // All banks are idle

                     b2x_req,      // Request to xfr_ctl

                     b2x_start,    // first chunk of transfer

                     b2x_last,     // last chunk of transfer

                     b2x_wrap,

                     b2x_id,       // Transfer ID

                     b2x_ba,       // bank address

                     b2x_addr,     // row/col address

                     b2x_len,      // transfer length

                     b2x_cmd,      // transfer command

                     x2b_ack,      // command accepted

                     /* Status to/from xfr_ctl */

                     b2x_tras_ok,  // TRAS OK for all banks

                     x2b_refresh,  // We did a refresh

                     x2b_pre_ok,   // OK to do a precharge (per bank)

                     x2b_act_ok,   // OK to do an activate

                     x2b_rdok,     // OK to do a read

                     x2b_wrok,     // OK to do a write

                     /* xfr msb address */

                     xfr_bank_sel,

                     sdr_req_norm_dma_last,

                     /* SDRAM Timing */

                     tras_delay,   // Active to precharge delay

                     trp_delay,    // Precharge to active delay

                     trcd_delay);  // Active to R/W delay

parameter  SDR_DW   = 16;  // SDR Data Width 

parameter  SDR_BW   = 2;   // SDR Byte Width

   input                        clk, reset_n;

   input [1:0]                   a2b_req_depth;

   /* Req from bank_ctl */

   input                        r2b_req, r2b_start, r2b_last,

                                r2b_write, r2b_wrap;

   input [`SDR_REQ_ID_W-1:0]     r2b_req_id;

   input [1:0]                   r2b_ba;

   input [12:0]          r2b_raddr;

   input [12:0]          r2b_caddr;

   input [`REQ_BW-1:0]           r2b_len;

   output                       b2r_arb_ok, b2r_ack;

   input                        sdr_req_norm_dma_last;

   /* Req to xfr_ctl */

   output                       b2x_idle, b2x_req, b2x_start, b2x_last,

                                b2x_tras_ok, b2x_wrap;

   output [`SDR_REQ_ID_W-1:0]    b2x_id;

   output [1:0]          b2x_ba;

   output [12:0]                 b2x_addr;

   output [`REQ_BW-1:0]  b2x_len;

   output [1:0]          b2x_cmd;

   input                        x2b_ack;

   /* Status from xfr_ctl */

   input [3:0]                   x2b_pre_ok;

   input                        x2b_refresh, x2b_act_ok, x2b_rdok,

                                x2b_wrok;

   input [3:0]                   tras_delay, trp_delay, trcd_delay;

   input [1:0] xfr_bank_sel;

   /****************************************************************************/

   // Internal Nets

   wire [3:0]                    r2i_req, i2r_ack, i2x_req,

                                i2x_start, i2x_last, i2x_wrap, tras_ok;

   wire [12:0]                   i2x_addr0, i2x_addr1, i2x_addr2, i2x_addr3;

   wire [`REQ_BW-1:0]    i2x_len0, i2x_len1, i2x_len2, i2x_len3;

   wire [1:0]                    i2x_cmd0, i2x_cmd1, i2x_cmd2, i2x_cmd3;

   wire [`SDR_REQ_ID_W-1:0]      i2x_id0, i2x_id1, i2x_id2, i2x_id3;

   reg                          b2x_req;

   wire                         b2x_idle, b2x_start, b2x_last, b2x_wrap;

   wire [`SDR_REQ_ID_W-1:0]      b2x_id;

   wire [12:0]                   b2x_addr;

   wire [`REQ_BW-1:0]    b2x_len;

   wire [1:0]                    b2x_cmd;

   wire [3:0]                    x2i_ack;

   reg [1:0]                     b2x_ba;

   reg [`SDR_REQ_ID_W-1:0]       curr_id;

   wire [1:0]                    xfr_ba;

   wire                         xfr_ba_last;

   wire [3:0]                    xfr_ok;

   // This 8 bit register stores the bank addresses for upto 4 requests.

   reg [7:0]                     rank_ba;

   reg [3:0]                     rank_ba_last;

   // This 3 bit counter counts the number of requests we have

   // buffered so far, legal values are 0, 1, 2, 3, or 4.

   reg [2:0]                     rank_cnt;

   wire [3:0]                    rank_req, rank_wr_sel;

   wire                         rank_fifo_wr, rank_fifo_rd;

   wire                         rank_fifo_full, rank_fifo_mt;

   wire [12:0] bank0_row, bank1_row, bank2_row, bank3_row;

   assign  b2x_tras_ok        = &tras_ok;

   // Distribute the request from req_gen

   assign r2i_req[0] = (r2b_ba == 2'b00) ? r2b_req & ~rank_fifo_full : 1'b0;

   assign r2i_req[1] = (r2b_ba == 2'b01) ? r2b_req & ~rank_fifo_full : 1'b0;

   assign r2i_req[2] = (r2b_ba == 2'b10) ? r2b_req & ~rank_fifo_full : 1'b0;

   assign r2i_req[3] = (r2b_ba == 2'b11) ? r2b_req & ~rank_fifo_full : 1'b0;

   /******************

   Modified the Better FPGA Timing Purpose

   assign b2r_ack = (r2b_ba == 2'b00) ? i2r_ack[0] :

                    (r2b_ba == 2'b01) ? i2r_ack[1] :

                    (r2b_ba == 2'b10) ? i2r_ack[2] :

                    (r2b_ba == 2'b11) ? i2r_ack[3] : 1'b0;

   ********************/

   // Assumption: Only one Ack Will be asserted at a time.

   assign b2r_ack  =|i2r_ack;

   assign b2r_arb_ok = ~rank_fifo_full;

   // Put the requests from the 4 bank_fsms into a 4 deep shift

   // register file. The earliest request is prioritized over the

   // later requests. Also the number of requests we are allowed to

   // buffer is limited by a 2 bit external input

   // Mux the req/cmd to xfr_ctl. Allow RD/WR commands from the request in

   // rank0, allow only PR/ACT commands from the requests in other ranks

   // If the rank_fifo is empty, send the request from the bank addressed by

   // r2b_ba 

   // In FPGA Mode, to improve the timing, also send the rank_ba

   assign xfr_ba = (`TARGET_DESIGN == `FPGA) ? rank_ba[1:0]:

                   ((rank_fifo_mt) ? r2b_ba : rank_ba[1:0]);

   assign xfr_ba_last = (`TARGET_DESIGN == `FPGA) ? rank_ba_last[0]:

                        ((rank_fifo_mt) ? sdr_req_norm_dma_last : rank_ba_last[0]);

   assign rank_req[0] = i2x_req[xfr_ba];     // each rank generates requests

   assign rank_req[1] = (rank_cnt < 3'h2) ? 1'b0 :

                        (rank_ba[3:2] == 2'b00) ? i2x_req[0] & ~i2x_cmd0[1] :

                        (rank_ba[3:2] == 2'b01) ? i2x_req[1] & ~i2x_cmd1[1] :

                        (rank_ba[3:2] == 2'b10) ? i2x_req[2] & ~i2x_cmd2[1] :

                        i2x_req[3] & ~i2x_cmd3[1];

   assign rank_req[2] = (rank_cnt < 3'h3) ? 1'b0 :

                        (rank_ba[5:4] == 2'b00) ? i2x_req[0] & ~i2x_cmd0[1] :

                        (rank_ba[5:4] == 2'b01) ? i2x_req[1] & ~i2x_cmd1[1] :

                        (rank_ba[5:4] == 2'b10) ? i2x_req[2] & ~i2x_cmd2[1] :

                        i2x_req[3] & ~i2x_cmd3[1];

   assign rank_req[3] = (rank_cnt < 3'h4) ? 1'b0 :

                        (rank_ba[7:6] == 2'b00) ? i2x_req[0] & ~i2x_cmd0[1] :

                        (rank_ba[7:6] == 2'b01) ? i2x_req[1] & ~i2x_cmd1[1] :

                        (rank_ba[7:6] == 2'b10) ? i2x_req[2] & ~i2x_cmd2[1] :

                        i2x_req[3] & ~i2x_cmd3[1];

   always @ (*) begin

      b2x_req = 1'b0;

      b2x_ba =   xfr_ba;

      if(`TARGET_DESIGN == `ASIC) begin // Support Multiple Rank request only on ASIC

         if (rank_req[0]) begin

            b2x_req = 1'b1;

            b2x_ba = xfr_ba;

         end // if (rank_req[0])

         else if (rank_req[1]) begin

           b2x_req = 1'b1;

           b2x_ba = rank_ba[3:2];

        end // if (rank_req[1])

        else if (rank_req[2]) begin

          b2x_req = 1'b1;

          b2x_ba = rank_ba[5:4];

        end // if (rank_req[2])

        else if (rank_req[3]) begin

          b2x_req = 1'b1;

          b2x_ba = rank_ba[7:6];

        end // if (rank_req[3])

      end else begin // If FPGA

         if (rank_req[0]) begin

            b2x_req = 1'b1;

         end

      end

  end // always @ (rank_req or rank_fifo_mt or r2b_ba or rank_ba)

   assign b2x_idle = rank_fifo_mt;

   assign b2x_start = i2x_start[b2x_ba];

   assign b2x_last = i2x_last[b2x_ba];

   assign b2x_wrap = i2x_wrap[b2x_ba];

   assign b2x_addr = (b2x_ba == 2'b11) ? i2x_addr3 :

                     (b2x_ba == 2'b10) ? i2x_addr2 :

                     (b2x_ba == 2'b01) ? i2x_addr1 : i2x_addr0;

   assign b2x_len = (b2x_ba == 2'b11) ? i2x_len3 :

                    (b2x_ba == 2'b10) ? i2x_len2 :

                    (b2x_ba == 2'b01) ? i2x_len1 : i2x_len0;

   assign b2x_cmd = (b2x_ba == 2'b11) ? i2x_cmd3 :

                    (b2x_ba == 2'b10) ? i2x_cmd2 :

                    (b2x_ba == 2'b01) ? i2x_cmd1 : i2x_cmd0;

   assign b2x_id = (b2x_ba == 2'b11) ? i2x_id3 :

                   (b2x_ba == 2'b10) ? i2x_id2 :

                   (b2x_ba == 2'b01) ? i2x_id1 : i2x_id0;

   assign x2i_ack[0] = (b2x_ba == 2'b00) ? x2b_ack : 1'b0;

   assign x2i_ack[1] = (b2x_ba == 2'b01) ? x2b_ack : 1'b0;

   assign x2i_ack[2] = (b2x_ba == 2'b10) ? x2b_ack : 1'b0;

   assign x2i_ack[3] = (b2x_ba == 2'b11) ? x2b_ack : 1'b0;

   // Rank Fifo

   // On a write write to selected rank and increment rank_cnt

   // On a read shift rank_ba right 2 bits and decrement rank_cnt

   assign rank_fifo_wr = b2r_ack;

   assign rank_fifo_rd = b2x_req & b2x_cmd[1] & x2b_ack;

   assign rank_wr_sel[0] = (rank_cnt == 3'h0) ? rank_fifo_wr :

                           (rank_cnt == 3'h1) ? rank_fifo_wr & rank_fifo_rd :

                           1'b0;

   assign rank_wr_sel[1] = (rank_cnt == 3'h1) ? rank_fifo_wr & ~rank_fifo_rd :

                           (rank_cnt == 3'h2) ? rank_fifo_wr & rank_fifo_rd :

                           1'b0;

   assign rank_wr_sel[2] = (rank_cnt == 3'h2) ? rank_fifo_wr & ~rank_fifo_rd :

                           (rank_cnt == 3'h3) ? rank_fifo_wr & rank_fifo_rd :

                           1'b0;

   assign rank_wr_sel[3] = (rank_cnt == 3'h3) ? rank_fifo_wr & ~rank_fifo_rd :

                           (rank_cnt == 3'h4) ? rank_fifo_wr & rank_fifo_rd :

                           1'b0;

   assign rank_fifo_mt = (rank_cnt == 3'b0) ? 1'b1 : 1'b0;

   assign rank_fifo_full = (rank_cnt[2]) ? 1'b1 :

                           (rank_cnt[1:0] == a2b_req_depth) ? 1'b1 : 1'b0;

   // FIFO Check

   // synopsys translate_off

   always @ (posedge clk) begin

      if (~rank_fifo_wr & rank_fifo_rd && rank_cnt == 3'h0) begin

         $display ("%t: %m: ERROR!!! Read from empty Fifo", $time);

         $stop;

      end // if (rank_fifo_rd && rank_cnt == 3'h0)

      if (rank_fifo_wr && ~rank_fifo_rd && rank_cnt == 3'h4) begin

         $display ("%t: %m: ERROR!!! Write to full Fifo", $time);

         $stop;

      end // if (rank_fifo_wr && ~rank_fifo_rd && rank_cnt == 3'h4)

   end // always @ (posedge clk)

   // synopsys translate_on

   always @ (posedge clk)

      if (~reset_n) begin

         rank_cnt <= 3'b0;

         rank_ba <= 8'b0;

         rank_ba_last <= 4'b0;

      end // if (~reset_n)

      else begin

         rank_cnt <= (rank_fifo_wr & ~rank_fifo_rd) ? rank_cnt + 3'b1 :

                     (~rank_fifo_wr & rank_fifo_rd) ? rank_cnt - 3'b1 :

                     rank_cnt;

         rank_ba[1:0] <= (rank_wr_sel[0]) ? r2b_ba :

                         (rank_fifo_rd) ? rank_ba[3:2] : rank_ba[1:0];

         rank_ba[3:2] <= (rank_wr_sel[1]) ? r2b_ba :

                         (rank_fifo_rd) ? rank_ba[5:4] : rank_ba[3:2];

         rank_ba[5:4] <= (rank_wr_sel[2]) ? r2b_ba :

                         (rank_fifo_rd) ? rank_ba[7:6] : rank_ba[5:4];

         rank_ba[7:6] <= (rank_wr_sel[3]) ? r2b_ba :

                         (rank_fifo_rd) ? 2'b00 : rank_ba[7:6];

         if(`TARGET_DESIGN == `ASIC) begin // This Logic is implemented for ASIC Only

            // Note: Currenly top-level does not generate the

            // sdr_req_norm_dma_last signal and can be tied zero at top-level

            rank_ba_last[0] <= (rank_wr_sel[0]) ? sdr_req_norm_dma_last :

                            (rank_fifo_rd) ?  rank_ba_last[1] : rank_ba_last[0];

            rank_ba_last[1] <= (rank_wr_sel[1]) ? sdr_req_norm_dma_last :

                               (rank_fifo_rd) ?  rank_ba_last[2] : rank_ba_last[1];

            rank_ba_last[2] <= (rank_wr_sel[2]) ? sdr_req_norm_dma_last :

                               (rank_fifo_rd) ?  rank_ba_last[3] : rank_ba_last[2];

            rank_ba_last[3] <= (rank_wr_sel[3]) ? sdr_req_norm_dma_last :

                               (rank_fifo_rd) ?  1'b0 : rank_ba_last[3];

         end

      end // else: !if(~reset_n)

   assign xfr_ok[0] = (xfr_ba == 2'b00) ? 1'b1 : 1'b0;

   assign xfr_ok[1] = (xfr_ba == 2'b01) ? 1'b1 : 1'b0;

   assign xfr_ok[2] = (xfr_ba == 2'b10) ? 1'b1 : 1'b0;

   assign xfr_ok[3] = (xfr_ba == 2'b11) ? 1'b1 : 1'b0;

   /****************************************************************************/

   // Instantiate Bank Ctl FSM 0

   sdrc_bank_fsm bank0_fsm (.clk (clk),

                           .reset_n (reset_n),

                           /* Req from req_gen */

                           .r2b_req (r2i_req[0]),

                           .r2b_req_id (r2b_req_id),

                           .r2b_start (r2b_start),

                           .r2b_last (r2b_last),

                           .r2b_wrap (r2b_wrap),

                           .r2b_raddr (r2b_raddr),

                           .r2b_caddr (r2b_caddr),

                           .r2b_len (r2b_len),

                           .r2b_write (r2b_write),

                           .b2r_ack (i2r_ack[0]),

                           .sdr_dma_last(rank_ba_last[0]),

                           /* Transfer request to xfr_ctl */

                           .b2x_req (i2x_req[0]),

                           .b2x_start (i2x_start[0]),

                           .b2x_last (i2x_last[0]),

                           .b2x_wrap (i2x_wrap[0]),

                           .b2x_id (i2x_id0),

                           .b2x_addr (i2x_addr0),

                           .b2x_len (i2x_len0),

                           .b2x_cmd (i2x_cmd0),

                           .x2b_ack (x2i_ack[0]),

                           /* Status to/from xfr_ctl */

                           .tras_ok (tras_ok[0]),

                           .xfr_ok (xfr_ok[0]),

                           .x2b_refresh (x2b_refresh),

                           .x2b_pre_ok (x2b_pre_ok[0]),

                           .x2b_act_ok (x2b_act_ok),

                           .x2b_rdok (x2b_rdok),

                           .x2b_wrok (x2b_wrok),

                           .bank_row(bank0_row),

                           /* SDRAM Timing */

                           .tras_delay (tras_delay),

                           .trp_delay (trp_delay),

                           .trcd_delay (trcd_delay));

   /****************************************************************************/

   // Instantiate Bank Ctl FSM 1

   sdrc_bank_fsm bank1_fsm (.clk (clk),

                           .reset_n (reset_n),

                           /* Req from req_gen */

                           .r2b_req (r2i_req[1]),

                           .r2b_req_id (r2b_req_id),

                           .r2b_start (r2b_start),

                           .r2b_last (r2b_last),

                           .r2b_wrap (r2b_wrap),

                           .r2b_raddr (r2b_raddr),

                           .r2b_caddr (r2b_caddr),

                           .r2b_len (r2b_len),

                           .r2b_write (r2b_write),

                           .b2r_ack (i2r_ack[1]),

                           .sdr_dma_last(rank_ba_last[1]),

                           /* Transfer request to xfr_ctl */

                           .b2x_req (i2x_req[1]),

                           .b2x_start (i2x_start[1]),

                           .b2x_last (i2x_last[1]),

                           .b2x_wrap (i2x_wrap[1]),

                           .b2x_id (i2x_id1),

                           .b2x_addr (i2x_addr1),

                           .b2x_len (i2x_len1),

                           .b2x_cmd (i2x_cmd1),

                           .x2b_ack (x2i_ack[1]),

                           /* Status to/from xfr_ctl */

                           .tras_ok (tras_ok[1]),

                           .xfr_ok (xfr_ok[1]),

                           .x2b_refresh (x2b_refresh),

                           .x2b_pre_ok (x2b_pre_ok[1]),

                           .x2b_act_ok (x2b_act_ok),

                           .x2b_rdok (x2b_rdok),

                           .x2b_wrok (x2b_wrok),

                           .bank_row(bank1_row),

                           /* SDRAM Timing */

                           .tras_delay (tras_delay),

                           .trp_delay (trp_delay),

                           .trcd_delay (trcd_delay));

   /****************************************************************************/

   // Instantiate Bank Ctl FSM 2

   sdrc_bank_fsm bank2_fsm (.clk (clk),

                           .reset_n (reset_n),

                           /* Req from req_gen */

                           .r2b_req (r2i_req[2]),

                           .r2b_req_id (r2b_req_id),

                           .r2b_start (r2b_start),

                           .r2b_last (r2b_last),

                           .r2b_wrap (r2b_wrap),

                           .r2b_raddr (r2b_raddr),

                           .r2b_caddr (r2b_caddr),

                           .r2b_len (r2b_len),

                           .r2b_write (r2b_write),

                           .b2r_ack (i2r_ack[2]),

                           .sdr_dma_last(rank_ba_last[2]),

                           /* Transfer request to xfr_ctl */

                           .b2x_req (i2x_req[2]),

                           .b2x_start (i2x_start[2]),

                           .b2x_last (i2x_last[2]),

                           .b2x_wrap (i2x_wrap[2]),

                           .b2x_id (i2x_id2),

                           .b2x_addr (i2x_addr2),

                           .b2x_len (i2x_len2),

                           .b2x_cmd (i2x_cmd2),

                           .x2b_ack (x2i_ack[2]),

                           /* Status to/from xfr_ctl */

                           .tras_ok (tras_ok[2]),

                           .xfr_ok (xfr_ok[2]),

                           .x2b_refresh (x2b_refresh),

                           .x2b_pre_ok (x2b_pre_ok[2]),

                           .x2b_act_ok (x2b_act_ok),

                           .x2b_rdok (x2b_rdok),

                           .x2b_wrok (x2b_wrok),

                           .bank_row(bank2_row),

                           /* SDRAM Timing */

                           .tras_delay (tras_delay),

                           .trp_delay (trp_delay),

                           .trcd_delay (trcd_delay));

   /****************************************************************************/

   // Instantiate Bank Ctl FSM 3

   sdrc_bank_fsm bank3_fsm (.clk (clk),

                           .reset_n (reset_n),

                           /* Req from req_gen */

                           .r2b_req (r2i_req[3]),

                           .r2b_req_id (r2b_req_id),

                           .r2b_start (r2b_start),

                           .r2b_last (r2b_last),

                           .r2b_wrap (r2b_wrap),

                           .r2b_raddr (r2b_raddr),

                           .r2b_caddr (r2b_caddr),

                           .r2b_len (r2b_len),

                           .r2b_write (r2b_write),

                           .b2r_ack (i2r_ack[3]),

                           .sdr_dma_last(rank_ba_last[3]),

                           /* Transfer request to xfr_ctl */

                           .b2x_req (i2x_req[3]),

                           .b2x_start (i2x_start[3]),

                           .b2x_last (i2x_last[3]),

                           .b2x_wrap (i2x_wrap[3]),

                           .b2x_id (i2x_id3),

                           .b2x_addr (i2x_addr3),

                           .b2x_len (i2x_len3),

                           .b2x_cmd (i2x_cmd3),

                           .x2b_ack (x2i_ack[3]),

                           /* Status to/from xfr_ctl */

                           .tras_ok (tras_ok[3]),

                           .xfr_ok (xfr_ok[3]),

                           .x2b_refresh (x2b_refresh),

                           .x2b_pre_ok (x2b_pre_ok[3]),

                           .x2b_act_ok (x2b_act_ok),

                           .x2b_rdok (x2b_rdok),

                           .x2b_wrok (x2b_wrok),

                           .bank_row(bank3_row),

                           /* SDRAM Timing */

                           .tras_delay (tras_delay),

                           .trp_delay (trp_delay),

                           .trcd_delay (trcd_delay));

/* address for current xfr, debug only */

wire [12:0] cur_row = (xfr_bank_sel==3) ? bank3_row:

                        (xfr_bank_sel==2) ? bank2_row:

                        (xfr_bank_sel==1) ? bank1_row: bank0_row;

endmodule // sdr_bank_ctl