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//////////////////////////////////////////////////////////////////////

////                                                              ////

////  OR1200's Instruction MMU top level                          ////

////                                                              ////

////  This file is part of the OpenRISC 1200 project              ////

////  http://www.opencores.org/cores/or1k/                        ////

////                                                              ////

////  Description                                                 ////

////  Instantiation of all IMMU blocks.                           ////

////                                                              ////

////  To Do:                                                      ////

////   - cache inhibit                                            ////

////                                                              ////

////  Author(s):                                                  ////

////      - Damjan Lampret, lampret@opencores.org                 ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

////                                                              ////

//// 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                     ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

//

// CVS Revision History

//

// $Log: not supported by cvs2svn $

// Revision 1.10  2002/09/16 03:08:56  lampret

// Disabled cache inhibit atttribute.

//

// Revision 1.9  2002/08/18 19:54:17  lampret

// Added store buffer.

//

// Revision 1.8  2002/08/14 06:23:50  lampret

// Disabled ITLB translation when 1) doing access to ITLB SPRs or 2) crossing page. This modification was tested only with parts of IMMU test - remaining test cases needs to be run.

//

// Revision 1.7  2002/08/12 05:31:30  lampret

// Delayed external access at page crossing.

//

// Revision 1.6  2002/03/29 15:16:56  lampret

// Some of the warnings fixed.

//

// Revision 1.5  2002/02/11 04:33:17  lampret

// Speed optimizations (removed duplicate _cyc_ and _stb_). Fixed D/IMMU cache-inhibit attr.

//

// Revision 1.4  2002/02/01 19:56:54  lampret

// Fixed combinational loops.

//

// Revision 1.3  2002/01/28 01:16:00  lampret

// Changed 'void' nop-ops instead of insn[0] to use insn[16]. Debug unit stalls the tick timer. Prepared new flag generation for add and and insns. Blocked DC/IC while they are turned off. Fixed I/D MMU SPRs layout except WAYs. TODO: smart IC invalidate, l.j 2 and TLB ways.

//

// Revision 1.2  2002/01/14 06:18:22  lampret

// Fixed mem2reg bug in FAST implementation. Updated debug unit to work with new genpc/if.

//

// Revision 1.1  2002/01/03 08:16:15  lampret

// New prefixes for RTL files, prefixed module names. Updated cache controllers and MMUs.

//

// Revision 1.6  2001/10/21 17:57:16  lampret

// Removed params from generic_XX.v. Added translate_off/on in sprs.v and id.v. Removed spr_addr from dc.v and ic.v. Fixed CR+LF.

//

// Revision 1.5  2001/10/14 13:12:09  lampret

// MP3 version.

//

// Revision 1.1.1.1  2001/10/06 10:18:36  igorm

// no message

//

// Revision 1.1  2001/08/17 08:03:35  lampret

// *** empty log message ***

//

// Revision 1.2  2001/07/22 03:31:53  lampret

// Fixed RAM's oen bug. Cache bypass under development.

//

// Revision 1.1  2001/07/20 00:46:03  lampret

// Development version of RTL. Libraries are missing.

//

//

// synopsys translate_off

`include "timescale.v"

// synopsys translate_on

`include "or1200_defines.v"

//

// Insn MMU

//

module or1200_immu_top(

        // Rst and clk

        clk, rst,

        // CPU i/f

        ic_en, immu_en, supv, icpu_adr_i, icpu_cycstb_i,

        icpu_adr_o, icpu_tag_o, icpu_rty_o, icpu_err_o,

        // SPR access

        spr_cs, spr_write, spr_addr, spr_dat_i, spr_dat_o,

`ifdef OR1200_BIST

        // RAM BIST

        scanb_rst, scanb_si, scanb_so, scanb_en, scanb_clk,

`endif

        // IC i/f

        icimmu_rty_i, icimmu_err_i, icimmu_tag_i, icimmu_adr_o, icimmu_cycstb_o, icimmu_ci_o

);

parameter dw = `OR1200_OPERAND_WIDTH;

parameter aw = `OR1200_OPERAND_WIDTH;

//

// I/O

//

//

// Clock and reset

//

input                           clk;

input                           rst;

//

// CPU I/F

//

input                           ic_en;

input                           immu_en;

input                           supv;

input   [aw-1:0]         icpu_adr_i;

input                           icpu_cycstb_i;

output  [aw-1:0]         icpu_adr_o;

output  [3:0]                    icpu_tag_o;

output                          icpu_rty_o;

output                          icpu_err_o;

//

// SPR access

//

input                           spr_cs;

input                           spr_write;

input   [aw-1:0]         spr_addr;

input   [31:0]                   spr_dat_i;

output  [31:0]                   spr_dat_o;

`ifdef OR1200_BIST

//

// RAM BIST

//

input                   scanb_rst,

                        scanb_si,

                        scanb_en,

                        scanb_clk;

output                  scanb_so;

`endif

//

// IC I/F

//

input                           icimmu_rty_i;

input                           icimmu_err_i;

input   [3:0]                    icimmu_tag_i;

output  [aw-1:0]         icimmu_adr_o;

output                          icimmu_cycstb_o;

output                          icimmu_ci_o;

//

// Internal wires and regs

//

wire                            itlb_spr_access;

wire    [31:`OR1200_IMMU_PS]    itlb_ppn;

wire                            itlb_hit;

wire                            itlb_uxe;

wire                            itlb_sxe;

wire    [31:0]                   itlb_dat_o;

wire                            itlb_en;

wire                            itlb_ci;

wire                            itlb_done;

wire                            fault;

wire                            miss;

wire                            page_cross;

reg     [31:0]                   icpu_adr_o;

`ifdef OR1200_NO_IMMU

`else

reg                             itlb_en_r;

reg                             dis_spr_access;

reg     [31:`OR1200_IMMU_PS]    icpu_vpn_r;

`endif

//

// Implemented bits inside match and translate registers

//

// itlbwYmrX: vpn 31-10  v 0

// itlbwYtrX: ppn 31-10  uxe 7  sxe 6

//

// itlb memory width:

// 19 bits for ppn

// 13 bits for vpn

// 1 bit for valid

// 2 bits for protection

// 1 bit for cache inhibit

//

// icpu_adr_o

//

`ifdef OR1200_REGISTERED_OUTPUTS

always @(posedge rst or posedge clk)

        if (rst)

                icpu_adr_o <= #1 32'h0000_0100;

        else

                icpu_adr_o <= #1 icpu_adr_i;

`else

Unsupported !!!

`endif

`ifdef OR1200_NO_IMMU

//

// Put all outputs in inactive state

//

assign spr_dat_o = 32'h00000000;

assign icimmu_adr_o = icpu_adr_i;

assign icpu_tag_o = icimmu_tag_i;

assign icimmu_cycstb_o = icpu_cycstb_i;

assign icpu_rty_o = icimmu_rty_i;

assign icpu_err_o = icimmu_err_i;

assign icimmu_ci_o = `OR1200_IMMU_CI;

`ifdef OR1200_BIST

assign scanb_so = scanb_si;

`endif

`else

//

// ITLB SPR access

//

// 1200 - 12FF  itlbmr w0

// 1200 - 123F  itlbmr w0 [63:0]

//

// 1300 - 13FF  itlbtr w0

// 1300 - 133F  itlbtr w0 [63:0]

//

assign itlb_spr_access = spr_cs & ~dis_spr_access;

//

// Disable ITLB SPR access

//

// This flop is used to mask ITLB miss/fault exception

// during first clock cycle of accessing ITLB SPR. In

// subsequent clock cycles it is assumed that ITLB SPR

// access was accomplished and that normal instruction fetching

// can proceed.

//

// spr_cs sets dis_spr_access and icpu_rty_o clears it.

//

always @(posedge clk or posedge rst)

        if (rst)

                dis_spr_access <= #1 1'b0;

        else if (!icpu_rty_o)

                dis_spr_access <= #1 1'b0;

        else if (spr_cs)

                dis_spr_access <= #1 1'b1;

//

// Tags:

//

// OR1200_DTAG_TE - TLB miss Exception

// OR1200_DTAG_PE - Page fault Exception

//

assign icpu_tag_o = miss ? `OR1200_DTAG_TE : fault ? `OR1200_DTAG_PE : icimmu_tag_i;

//

// icpu_rty_o

//

// assign icpu_rty_o = !icpu_err_o & icimmu_rty_i;

assign icpu_rty_o = icimmu_rty_i | itlb_spr_access & immu_en;

//

// icpu_err_o

//

assign icpu_err_o = miss | fault | icimmu_err_i;

//

// Assert itlb_en_r after one clock cycle and when there is no

// ITLB SPR access

//

always @(posedge clk or posedge rst)

        if (rst)

                itlb_en_r <= #1 1'b0;

        else

                itlb_en_r <= #1 itlb_en & ~itlb_spr_access;

//

// ITLB lookup successful

//

assign itlb_done = itlb_en_r & ~page_cross;

//

// Cut transfer if something goes wrong with translation. If IC is disabled,

// use delayed signals.

//

// assign icimmu_cycstb_o = (!ic_en & immu_en) ? ~(miss | fault) & icpu_cycstb_i & ~page_cross : (miss | fault) ? 1'b0 : icpu_cycstb_i & ~page_cross; // DL

assign icimmu_cycstb_o = immu_en ? ~(miss | fault) & icpu_cycstb_i & ~page_cross & itlb_done : icpu_cycstb_i & ~page_cross;

//

// Cache Inhibit

//

// Cache inhibit is not really needed for instruction memory subsystem.

// If we would do it, we would do it like this.

// assign icimmu_ci_o = immu_en ? itlb_done & itlb_ci : `OR1200_IMMU_CI;

// However this causes a async combinational loop so we stick to

// no cache inhibit.

assign icimmu_ci_o = `OR1200_IMMU_CI;

//

// Page cross

//

// Asserted when CPU address crosses page boundary. Most of the time it is zero.

//

assign page_cross = icpu_adr_i[31:`OR1200_IMMU_PS] != icpu_vpn_r;

//

// Register icpu_adr_i's VPN for use when IMMU is not enabled but PPN is expected to come

// one clock cycle after offset part.

//

always @(posedge clk or posedge rst)

        if (rst)

                icpu_vpn_r <= #1 {31-`OR1200_IMMU_PS{1'b0}};

        else

                icpu_vpn_r <= #1 icpu_adr_i[31:`OR1200_IMMU_PS];

//

// Physical address is either translated virtual address or

// simply equal when IMMU is disabled

//

assign icimmu_adr_o = itlb_done ? {itlb_ppn, icpu_adr_i[`OR1200_IMMU_PS-1:0]} : {icpu_vpn_r, icpu_adr_i[`OR1200_IMMU_PS-1:0]}; // DL: immu_en

//

// Output to SPRS unit

//

assign spr_dat_o = spr_cs ? itlb_dat_o : 32'h00000000;

//

// Page fault exception logic

//

assign fault = itlb_done &

                        (  (!supv & !itlb_uxe)          // Execute in user mode not enabled

                        || (supv & !itlb_sxe));         // Execute in supv mode not enabled

//

// TLB Miss exception logic

//

assign miss = itlb_done & !itlb_hit;

//

// ITLB Enable

//

assign itlb_en = immu_en & icpu_cycstb_i;

//

// Instantiation of ITLB

//

or1200_immu_tlb or1200_immu_tlb(

        // Rst and clk

        .clk(clk),

        .rst(rst),

        // I/F for translation

        .tlb_en(itlb_en),

        .vaddr(icpu_adr_i),

        .hit(itlb_hit),

        .ppn(itlb_ppn),

        .uxe(itlb_uxe),

        .sxe(itlb_sxe),

        .ci(itlb_ci),

`ifdef OR1200_BIST

        // RAM BIST

        .scanb_rst(scanb_rst),

        .scanb_si(scanb_si),

        .scanb_so(scanb_so),

        .scanb_en(scanb_en),

        .scanb_clk(scanb_clk),

`endif

        // SPR access

        .spr_cs(itlb_spr_access),

        .spr_write(spr_write),

        .spr_addr(spr_addr),

        .spr_dat_i(spr_dat_i),

        .spr_dat_o(itlb_dat_o)

);

`endif

endmodule