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/*

 * Wrapper for Xilinx MIG'd DDR2 controller, allowing 3 masters

 * to contol the single interface.

 */

module xilinx_ddr2

  (

   // Inputs

    input [31:0] wbm0_adr_i,

    input [1:0]  wbm0_bte_i,

    input [2:0]  wbm0_cti_i,

    input        wbm0_cyc_i,

    input [31:0] wbm0_dat_i,

    input [3:0]  wbm0_sel_i,

    input        wbm0_stb_i,

    input        wbm0_we_i,

   // Outputs

    output       wbm0_ack_o,

    output       wbm0_err_o,

    output       wbm0_rty_o,

    output [31:0] wbm0_dat_o,

   // Inputs

    input [31:0]  wbm1_adr_i,

    input [1:0]   wbm1_bte_i,

    input [2:0]   wbm1_cti_i,

    input         wbm1_cyc_i,

    input [31:0]  wbm1_dat_i,

    input [3:0]   wbm1_sel_i,

    input         wbm1_stb_i,

    input         wbm1_we_i,

   // Outputs

    output        wbm1_ack_o,

    output        wbm1_err_o,

    output        wbm1_rty_o,

    output [31:0] wbm1_dat_o,

   // Inputs

    input [31:0]  wbm2_adr_i,

    input [1:0]   wbm2_bte_i,

    input [2:0]   wbm2_cti_i,

    input         wbm2_cyc_i,

    input [31:0]  wbm2_dat_i,

    input [3:0]   wbm2_sel_i,

    input         wbm2_stb_i,

    input         wbm2_we_i,

   // Outputs

    output        wbm2_ack_o,

    output        wbm2_err_o,

    output        wbm2_rty_o,

    output [31:0] wbm2_dat_o,

    input         wb_clk,

    input         wb_rst,

    output [12:0] ddr2_a,

    output [2:0]  ddr2_ba,

    output            ddr2_ras_n,

    output            ddr2_cas_n,

    output            ddr2_we_n,

    output        ddr2_rzq,

    output        ddr2_zio,

    output        ddr2_odt,

    output        ddr2_cke,

    output        ddr2_dm,

    output        ddr2_udm,

    inout [15:0]  ddr2_dq,

    inout         ddr2_dqs,

    inout         ddr2_dqs_n,

    inout         ddr2_udqs,

    inout         ddr2_udqs_n,

    output        ddr2_ck,

    output        ddr2_ck_n,

    input         ddr2_if_clk,

    input         clk100,

    input         ddr2_if_rst

   );

   // Internal wires to actual RAM

   wire [31:0]     wbs_ram_adr_i;

   wire [1:0]      wbs_ram_bte_i;

   wire [2:0]      wbs_ram_cti_i;

   wire           wbs_ram_cyc_i;

   wire [31:0]     wbs_ram_dat_i;

   wire [3:0]      wbs_ram_sel_i;

   wire           wbs_ram_stb_i;

   wire           wbs_ram_we_i;

   wire           wbs_ram_ack_o;

   wire [31:0]     wbs_ram_dat_o;

   reg [2:0]       input_select, last_selected;

   wire           arb_for_wbm0, arb_for_wbm1, arb_for_wbm2;

   // Wires allowing selection of new input

   assign arb_for_wbm0 = (last_selected[1] | last_selected[2] |

                          !wbm1_cyc_i | !wbm2_cyc_i) & !(|input_select);

   assign arb_for_wbm1 = (last_selected[0] | last_selected[2] |

                          !wbm0_cyc_i | !wbm2_cyc_i) & !(|input_select);

   assign arb_for_wbm2 = (last_selected[0] | last_selected[1] |

                          !wbm0_cyc_i | !wbm1_cyc_i) & !(|input_select);

   // Master select logic

   always @(posedge wb_clk)

     if (wb_rst)

       input_select <= 0;

     else if ((input_select[0] & !wbm0_cyc_i) | (input_select[1] & !wbm1_cyc_i)

              | (input_select[2] & !wbm2_cyc_i))

       input_select <= 0;

     else if (!(&input_select) & wbm0_cyc_i & arb_for_wbm0)

       input_select <= 3'b001;

     else if (!(&input_select) & wbm1_cyc_i & arb_for_wbm1)

       input_select <= 3'b010;

     else if (!(&input_select) & wbm2_cyc_i & arb_for_wbm2)

       input_select <= 3'b100;

   always @(posedge wb_clk)

     if (wb_rst)

       last_selected <= 0;

     else if (!(&input_select) & wbm0_cyc_i & arb_for_wbm0)

       last_selected <= 3'b001;

     else if (!(&input_select) & wbm1_cyc_i & arb_for_wbm1)

       last_selected <= 3'b010;

     else if (!(&input_select) & wbm2_cyc_i & arb_for_wbm2)

       last_selected <= 3'b100;

   // Mux input signals to RAM (default to wbm0)

   assign wbs_ram_adr_i = (input_select[2]) ? wbm2_adr_i :

                            (input_select[1]) ? wbm1_adr_i :

                            (input_select[0]) ? wbm0_adr_i : 0;

   assign wbs_ram_bte_i = (input_select[2]) ? wbm2_bte_i :

                            (input_select[1]) ? wbm1_bte_i :

                            (input_select[0]) ? wbm0_bte_i : 0;

   assign wbs_ram_cti_i = (input_select[2]) ? wbm2_cti_i :

                            (input_select[1]) ? wbm1_cti_i :

                            (input_select[0]) ? wbm0_cti_i : 0;

   assign wbs_ram_cyc_i = (input_select[2]) ? wbm2_cyc_i :

                            (input_select[1]) ? wbm1_cyc_i :

                            (input_select[0]) ? wbm0_cyc_i : 0;

   assign wbs_ram_dat_i = (input_select[2]) ? wbm2_dat_i :

                            (input_select[1]) ? wbm1_dat_i :

                            (input_select[0]) ? wbm0_dat_i : 0;

   assign wbs_ram_sel_i = (input_select[2]) ? wbm2_sel_i :

                            (input_select[1]) ? wbm1_sel_i :

                            (input_select[0]) ? wbm0_sel_i : 0;

   assign wbs_ram_stb_i = (input_select[2]) ? wbm2_stb_i :

                            (input_select[1]) ? wbm1_stb_i :

                            (input_select[0]) ? wbm0_stb_i : 0;

   assign wbs_ram_we_i  = (input_select[2]) ? wbm2_we_i  :

                            (input_select[1]) ? wbm1_we_i  :

                            (input_select[0]) ? wbm0_we_i : 0;

   // Output from RAM, gate the ACK, ERR, RTY signals appropriately

   assign wbm0_dat_o = wbs_ram_dat_o;

   assign wbm0_ack_o = wbs_ram_ack_o & input_select[0];

   assign wbm0_err_o = 0;

   assign wbm0_rty_o = 0;

   assign wbm1_dat_o = wbs_ram_dat_o;

   assign wbm1_ack_o = wbs_ram_ack_o & input_select[1];

   assign wbm1_err_o = 0;

   assign wbm1_rty_o = 0;

   assign wbm2_dat_o = wbs_ram_dat_o;

   assign wbm2_ack_o = wbs_ram_ack_o & input_select[2];

   assign wbm2_err_o = 0;

   assign wbm2_rty_o = 0;

    xilinx_ddr2_if xilinx_ddr2_if0

     (

      .wb_dat_o                         (wbs_ram_dat_o),

      .wb_ack_o                         (wbs_ram_ack_o),

      .wb_adr_i                         (wbs_ram_adr_i[31:0]),

      .wb_stb_i                         (wbs_ram_stb_i),

      .wb_cti_i                         (wbs_ram_cti_i),

      .wb_bte_i                         (wbs_ram_bte_i),

      .wb_cyc_i                         (wbs_ram_cyc_i),

      .wb_we_i                          (wbs_ram_we_i),

      .wb_sel_i                         (wbs_ram_sel_i[3:0]),

      .wb_dat_i                         (wbs_ram_dat_i[31:0]),

      .ddr2_a                           (ddr2_a[12:0]),

      .ddr2_ba                          (ddr2_ba),

      .ddr2_ras_n                       (ddr2_ras_n),

      .ddr2_cas_n                       (ddr2_cas_n),

      .ddr2_we_n                        (ddr2_we_n),

      .ddr2_rzq                 (ddr2_rzq),

      .ddr2_zio                         (ddr2_zio),

      .ddr2_odt                         (ddr2_odt),

      .ddr2_cke                         (ddr2_cke),

      .ddr2_dm                          (ddr2_dm),

      .ddr2_udm                         (ddr2_udm),

      .ddr2_ck                          (ddr2_ck),

      .ddr2_ck_n                        (ddr2_ck_n),

      .ddr2_dq                          (ddr2_dq),

      .ddr2_dqs                         (ddr2_dqs),

      .ddr2_dqs_n                       (ddr2_dqs_n),

      .ddr2_udqs                        (ddr2_udqs),

      .ddr2_udqs_n                      (ddr2_udqs_n),

      .ddr2_if_clk                      (ddr2_if_clk),

      .idly_clk_100                     (clk100), //SJK this can be removed, not needed

      .ddr2_if_rst                      (ddr2_if_rst),

      .wb_clk                           (wb_clk),

      .wb_rst                           (wb_rst));

endmodule