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

////                                                              ////

////  OR1200's interface to SPRs                                  ////

////                                                              ////

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

////  http://www.opencores.org/project,or1k                       ////

////                                                              ////

////  Description                                                 ////

////  Decoding of SPR addresses and access to SPRs                ////

////                                                              ////

////  To Do:                                                      ////

////   - make it smaller and faster                               ////

////                                                              ////

////  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                     ////

////                                                              ////

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

//

// $Log: or1200_sprs.v,v $

// Revision 2.0  2010/06/30 11:00:00  ORSoC

// Major update: 

// Structure reordered and bugs fixed. 

// synopsys translate_off

`include "timescale.v"

// synopsys translate_on

`include "or1200_defines.v"

module or1200_sprs(

                // Clk & Rst

                clk, rst,

                // Internal CPU interface

                flagforw, flag_we, flag, cyforw, cy_we, carry,

                addrbase, addrofs, dat_i, branch_op, ex_spr_read, ex_spr_write,

                epcr, eear, esr, except_started,

                to_wbmux, epcr_we, eear_we, esr_we, pc_we, sr_we, to_sr, sr,

                spr_dat_cfgr, spr_dat_rf, spr_dat_npc, spr_dat_ppc, spr_dat_mac,

                boot_adr_sel_i,

                // Floating point SPR input

                fpcsr, fpcsr_we, spr_dat_fpu,

                // From/to other RISC units

                spr_dat_pic, spr_dat_tt, spr_dat_pm,

                spr_dat_dmmu, spr_dat_immu, spr_dat_du,

                spr_addr, spr_dat_o, spr_cs, spr_we,

                du_addr, du_dat_du, du_read,

                du_write, du_dat_cpu

);

parameter width = `OR1200_OPERAND_WIDTH;

//

// I/O Ports

//

//

// Internal CPU interface

//

input                           clk;            // Clock

input                           rst;            // Reset

input                           flagforw;       // From ALU

input                           flag_we;        // From ALU

output                          flag;           // SR[F]

input                           cyforw;         // From ALU

input                           cy_we;          // From ALU

output                          carry;          // SR[CY]

input   [width-1:0]              addrbase;       // SPR base address

input   [15:0]                   addrofs;        // SPR offset

input   [width-1:0]              dat_i;          // SPR write data

input                           ex_spr_read;    // l.mfspr in EX

input                           ex_spr_write;   // l.mtspr in EX

input   [`OR1200_BRANCHOP_WIDTH-1:0]     branch_op;      // Branch operation

input   [width-1:0]              epcr /* verilator public */;            // EPCR0

input   [width-1:0]              eear /* verilator public */;            // EEAR0

input   [`OR1200_SR_WIDTH-1:0]   esr /* verilator public */;             // ESR0

input                           except_started; // Exception was started

output  [width-1:0]              to_wbmux;       // For l.mfspr

output                          epcr_we;        // EPCR0 write enable

output                          eear_we;        // EEAR0 write enable

output                          esr_we;         // ESR0 write enable

output                          pc_we;          // PC write enable

output                          sr_we;          // Write enable SR

output  [`OR1200_SR_WIDTH-1:0]   to_sr;          // Data to SR

output  [`OR1200_SR_WIDTH-1:0]   sr /* verilator public */;              // SR

input   [31:0]                   spr_dat_cfgr;   // Data from CFGR

input   [31:0]                   spr_dat_rf;     // Data from RF

input   [31:0]                   spr_dat_npc;    // Data from NPC

input   [31:0]                   spr_dat_ppc;    // Data from PPC   

input   [31:0]                   spr_dat_mac;    // Data from MAC

input                           boot_adr_sel_i;

input   [`OR1200_FPCSR_WIDTH-1:0]       fpcsr;   // FPCSR

output                          fpcsr_we;       // Write enable FPCSR   

input [31:0]                     spr_dat_fpu;    // Data from FPU

//

// To/from other RISC units

//

input   [31:0]                   spr_dat_pic;    // Data from PIC

input   [31:0]                   spr_dat_tt;     // Data from TT

input   [31:0]                   spr_dat_pm;     // Data from PM

input   [31:0]                   spr_dat_dmmu;   // Data from DMMU

input   [31:0]                   spr_dat_immu;   // Data from IMMU

input   [31:0]                   spr_dat_du;     // Data from DU

output  [31:0]                   spr_addr;       // SPR Address

output  [31:0]                   spr_dat_o;      // Data to unit

output  [31:0]                   spr_cs;         // Unit select

output                          spr_we;         // SPR write enable

//

// To/from Debug Unit

//

input   [width-1:0]              du_addr;        // Address

input   [width-1:0]              du_dat_du;      // Data from DU to SPRS

input                           du_read;        // Read qualifier

input                           du_write;       // Write qualifier

output  [width-1:0]              du_dat_cpu;     // Data from SPRS to DU

//

// Internal regs & wires

//

reg     [`OR1200_SR_WIDTH-1:0]   sr_reg;                 // SR

reg                             sr_reg_bit_eph;         // SR_EPH bit

reg                             sr_reg_bit_eph_select;  // SR_EPH select

wire                            sr_reg_bit_eph_muxed;   // SR_EPH muxed bit

reg     [`OR1200_SR_WIDTH-1:0]   sr;                     // SR

reg     [width-1:0]              to_wbmux;       // For l.mfspr

wire                            cfgr_sel;       // Select for cfg regs

wire                            rf_sel;         // Select for RF

wire                            npc_sel;        // Select for NPC

wire                            ppc_sel;        // Select for PPC

wire                            sr_sel;         // Select for SR        

wire                            epcr_sel;       // Select for EPCR0

wire                            eear_sel;       // Select for EEAR0

wire                            esr_sel;        // Select for ESR0

wire                            fpcsr_sel;      // Select for FPCSR   

wire    [31:0]                   sys_data;       // Read data from system SPRs

wire                            du_access;      // Debug unit access

reg     [31:0]                   unqualified_cs; // Unqualified chip selects

   wire                         ex_spr_write; // jb

//

// Decide if it is debug unit access

//

assign du_access = du_read | du_write;

//

// Generate SPR address from base address and offset

// OR from debug unit address

//

assign spr_addr = du_access ? du_addr : (addrbase | {16'h0000, addrofs});

//

// SPR is written by debug unit or by l.mtspr

//

assign spr_dat_o = du_write ? du_dat_du : dat_i;

//

// debug unit data input:

//  - read of SPRS by debug unit

//  - write into debug unit SPRs by debug unit itself

//  - write into debug unit SPRs by l.mtspr

//

assign du_dat_cpu = du_read ? to_wbmux : du_write ? du_dat_du : dat_i;

//

// Write into SPRs when DU or l.mtspr

//

assign spr_we = du_write | ( ex_spr_write & !du_access );

//

// Qualify chip selects

//

assign spr_cs = unqualified_cs & {32{du_read | du_write | ex_spr_read | (ex_spr_write & sr[`OR1200_SR_SM])}};

//

// Decoding of groups

//

always @(spr_addr)

        case (spr_addr[`OR1200_SPR_GROUP_BITS]) // synopsys parallel_case

                `OR1200_SPR_GROUP_WIDTH'd00: unqualified_cs = 32'b00000000_00000000_00000000_00000001;

                `OR1200_SPR_GROUP_WIDTH'd01: unqualified_cs = 32'b00000000_00000000_00000000_00000010;

                `OR1200_SPR_GROUP_WIDTH'd02: unqualified_cs = 32'b00000000_00000000_00000000_00000100;

                `OR1200_SPR_GROUP_WIDTH'd03: unqualified_cs = 32'b00000000_00000000_00000000_00001000;

                `OR1200_SPR_GROUP_WIDTH'd04: unqualified_cs = 32'b00000000_00000000_00000000_00010000;

                `OR1200_SPR_GROUP_WIDTH'd05: unqualified_cs = 32'b00000000_00000000_00000000_00100000;

                `OR1200_SPR_GROUP_WIDTH'd06: unqualified_cs = 32'b00000000_00000000_00000000_01000000;

                `OR1200_SPR_GROUP_WIDTH'd07: unqualified_cs = 32'b00000000_00000000_00000000_10000000;

                `OR1200_SPR_GROUP_WIDTH'd08: unqualified_cs = 32'b00000000_00000000_00000001_00000000;

                `OR1200_SPR_GROUP_WIDTH'd09: unqualified_cs = 32'b00000000_00000000_00000010_00000000;

                `OR1200_SPR_GROUP_WIDTH'd10: unqualified_cs = 32'b00000000_00000000_00000100_00000000;

                `OR1200_SPR_GROUP_WIDTH'd11: unqualified_cs = 32'b00000000_00000000_00001000_00000000;

                `OR1200_SPR_GROUP_WIDTH'd12: unqualified_cs = 32'b00000000_00000000_00010000_00000000;

                `OR1200_SPR_GROUP_WIDTH'd13: unqualified_cs = 32'b00000000_00000000_00100000_00000000;

                `OR1200_SPR_GROUP_WIDTH'd14: unqualified_cs = 32'b00000000_00000000_01000000_00000000;

                `OR1200_SPR_GROUP_WIDTH'd15: unqualified_cs = 32'b00000000_00000000_10000000_00000000;

                `OR1200_SPR_GROUP_WIDTH'd16: unqualified_cs = 32'b00000000_00000001_00000000_00000000;

                `OR1200_SPR_GROUP_WIDTH'd17: unqualified_cs = 32'b00000000_00000010_00000000_00000000;

                `OR1200_SPR_GROUP_WIDTH'd18: unqualified_cs = 32'b00000000_00000100_00000000_00000000;

                `OR1200_SPR_GROUP_WIDTH'd19: unqualified_cs = 32'b00000000_00001000_00000000_00000000;

                `OR1200_SPR_GROUP_WIDTH'd20: unqualified_cs = 32'b00000000_00010000_00000000_00000000;

                `OR1200_SPR_GROUP_WIDTH'd21: unqualified_cs = 32'b00000000_00100000_00000000_00000000;

                `OR1200_SPR_GROUP_WIDTH'd22: unqualified_cs = 32'b00000000_01000000_00000000_00000000;

                `OR1200_SPR_GROUP_WIDTH'd23: unqualified_cs = 32'b00000000_10000000_00000000_00000000;

                `OR1200_SPR_GROUP_WIDTH'd24: unqualified_cs = 32'b00000001_00000000_00000000_00000000;

                `OR1200_SPR_GROUP_WIDTH'd25: unqualified_cs = 32'b00000010_00000000_00000000_00000000;

                `OR1200_SPR_GROUP_WIDTH'd26: unqualified_cs = 32'b00000100_00000000_00000000_00000000;

                `OR1200_SPR_GROUP_WIDTH'd27: unqualified_cs = 32'b00001000_00000000_00000000_00000000;

                `OR1200_SPR_GROUP_WIDTH'd28: unqualified_cs = 32'b00010000_00000000_00000000_00000000;

                `OR1200_SPR_GROUP_WIDTH'd29: unqualified_cs = 32'b00100000_00000000_00000000_00000000;

                `OR1200_SPR_GROUP_WIDTH'd30: unqualified_cs = 32'b01000000_00000000_00000000_00000000;

                `OR1200_SPR_GROUP_WIDTH'd31: unqualified_cs = 32'b10000000_00000000_00000000_00000000;

        endcase

//

// SPRs System Group

//

//

// What to write into SR

//

assign to_sr[`OR1200_SR_FO:`OR1200_SR_OV] =

                (except_started) ? sr[`OR1200_SR_FO:`OR1200_SR_OV] :

                (branch_op == `OR1200_BRANCHOP_RFE) ? esr[`OR1200_SR_FO:`OR1200_SR_OV] :

                (spr_we && sr_sel) ? {1'b1, spr_dat_o[`OR1200_SR_FO-1:`OR1200_SR_OV]}:

                sr[`OR1200_SR_FO:`OR1200_SR_OV];

assign to_sr[`OR1200_SR_TED] =

                (except_started) ? 1'b1 :

                (branch_op == `OR1200_BRANCHOP_RFE) ? esr[`OR1200_SR_TED] :

                (spr_we && sr_sel) ? spr_dat_o[`OR1200_SR_TED]:

                sr[`OR1200_SR_TED];

assign to_sr[`OR1200_SR_CY] =

                (except_started) ? sr[`OR1200_SR_CY] :

                (branch_op == `OR1200_BRANCHOP_RFE) ? esr[`OR1200_SR_CY] :

                cy_we ? cyforw :

                (spr_we && sr_sel) ? spr_dat_o[`OR1200_SR_CY] :

                sr[`OR1200_SR_CY];

assign to_sr[`OR1200_SR_F] =

                (except_started) ? sr[`OR1200_SR_F] :

                (branch_op == `OR1200_BRANCHOP_RFE) ? esr[`OR1200_SR_F] :

                flag_we ? flagforw :

                (spr_we && sr_sel) ? spr_dat_o[`OR1200_SR_F] :

                sr[`OR1200_SR_F];

assign to_sr[`OR1200_SR_CE:`OR1200_SR_SM] =

                (except_started) ? {sr[`OR1200_SR_CE:`OR1200_SR_LEE], 2'b00, sr[`OR1200_SR_ICE:`OR1200_SR_DCE], 3'b001} :

                (branch_op == `OR1200_BRANCHOP_RFE) ? esr[`OR1200_SR_CE:`OR1200_SR_SM] :

                (spr_we && sr_sel) ? spr_dat_o[`OR1200_SR_CE:`OR1200_SR_SM]:

                sr[`OR1200_SR_CE:`OR1200_SR_SM];

//

// Selects for system SPRs

//

assign cfgr_sel = (spr_cs[`OR1200_SPR_GROUP_SYS] && (spr_addr[10:4] == `OR1200_SPR_CFGR));

assign rf_sel = (spr_cs[`OR1200_SPR_GROUP_SYS] && (spr_addr[10:5] == `OR1200_SPR_RF));

assign npc_sel = (spr_cs[`OR1200_SPR_GROUP_SYS] && (spr_addr[10:0] == `OR1200_SPR_NPC));

assign ppc_sel = (spr_cs[`OR1200_SPR_GROUP_SYS] && (spr_addr[10:0] == `OR1200_SPR_PPC));

assign sr_sel = (spr_cs[`OR1200_SPR_GROUP_SYS] && (spr_addr[10:0] == `OR1200_SPR_SR));

assign epcr_sel = (spr_cs[`OR1200_SPR_GROUP_SYS] && (spr_addr[10:0] == `OR1200_SPR_EPCR));

assign eear_sel = (spr_cs[`OR1200_SPR_GROUP_SYS] && (spr_addr[10:0] == `OR1200_SPR_EEAR));

assign esr_sel = (spr_cs[`OR1200_SPR_GROUP_SYS] && (spr_addr[10:0] == `OR1200_SPR_ESR));

assign fpcsr_sel = (spr_cs[`OR1200_SPR_GROUP_SYS] && (spr_addr[10:0] == `OR1200_SPR_FPCSR));

//

// Write enables for system SPRs

//

assign sr_we = (spr_we && sr_sel) | (branch_op == `OR1200_BRANCHOP_RFE) | flag_we | cy_we;

assign pc_we = (du_write && (npc_sel | ppc_sel));

assign epcr_we = (spr_we && epcr_sel);

assign eear_we = (spr_we && eear_sel);

assign esr_we = (spr_we && esr_sel);

assign fpcsr_we = (spr_we && fpcsr_sel);

//

// Output from system SPRs

//

assign sys_data = (spr_dat_cfgr & {32{cfgr_sel}}) |

                  (spr_dat_rf & {32{rf_sel}}) |

                  (spr_dat_npc & {32{npc_sel}}) |

                  (spr_dat_ppc & {32{ppc_sel}}) |

                  ({{32-`OR1200_SR_WIDTH{1'b0}},sr} & {32{sr_sel}}) |

                  (epcr & {32{epcr_sel}}) |

                  (eear & {32{eear_sel}}) |

                  ({{32-`OR1200_FPCSR_WIDTH{1'b0}},fpcsr} & {32{fpcsr_sel}}) |

                  ({{32-`OR1200_SR_WIDTH{1'b0}},esr} & {32{esr_sel}});

//

// Flag alias

//

assign flag = sr[`OR1200_SR_F];

//

// Carry alias

//

assign carry = sr[`OR1200_SR_CY];

//

// Supervision register

//

always @(posedge clk or posedge rst)

        if (rst)

                sr_reg <=  {2'h1, `OR1200_SR_EPH_DEF, {`OR1200_SR_WIDTH-4{1'b0}}, 1'b1};

        else if (except_started)

                sr_reg <=  to_sr[`OR1200_SR_WIDTH-1:0];

        else if (sr_we)

                sr_reg <=  to_sr[`OR1200_SR_WIDTH-1:0];

// EPH part of Supervision register

always @(posedge clk or posedge rst)

        // default value 

        if (rst) begin

                sr_reg_bit_eph <=  `OR1200_SR_EPH_DEF;

                sr_reg_bit_eph_select <=  1'b1; // select async. value due to reset state

        end

        // selected value (different from default) is written into FF after reset state

        else if (sr_reg_bit_eph_select) begin

                sr_reg_bit_eph <=  boot_adr_sel_i;      // dynamic value can only be assigned to FF out of reset! 

                sr_reg_bit_eph_select <=  1'b0; // select FF value 

        end

        else if (sr_we) begin

                sr_reg_bit_eph <=  to_sr[`OR1200_SR_EPH];

        end

// select async. value of EPH bit after reset 

assign  sr_reg_bit_eph_muxed = (sr_reg_bit_eph_select) ? boot_adr_sel_i : sr_reg_bit_eph;

// EPH part joined together with rest of Supervision register

always @(sr_reg or sr_reg_bit_eph_muxed)

        sr = {sr_reg[`OR1200_SR_WIDTH-1:`OR1200_SR_WIDTH-2], sr_reg_bit_eph_muxed, sr_reg[`OR1200_SR_WIDTH-4:0]};

`ifdef verilator

   // Function to access various sprs (for Verilator). Have to hide this from

   // simulator, since functions with no inputs are not allowed in IEEE

   // 1364-2001.

   function [31:0] get_sr;

      // verilator public

      get_sr = sr;

   endfunction // get_sr

   function [31:0] get_epcr;

      // verilator public

      get_epcr = epcr;

   endfunction // get_epcr

   function [31:0] get_eear;

      // verilator public

      get_eear = eear;

   endfunction // get_eear

   function [31:0] get_esr;

      // verilator public

      get_esr = esr;

   endfunction // get_esr

`endif

//

// MTSPR/MFSPR interface

//

always @(spr_addr or sys_data or spr_dat_mac or spr_dat_pic or spr_dat_pm or

         spr_dat_fpu or

        spr_dat_dmmu or spr_dat_immu or spr_dat_du or spr_dat_tt) begin

                casex (spr_addr[`OR1200_SPR_GROUP_BITS]) // synopsys parallel_case

                        `OR1200_SPR_GROUP_SYS:

                                to_wbmux = sys_data;

                        `OR1200_SPR_GROUP_TT:

                                to_wbmux = spr_dat_tt;

                        `OR1200_SPR_GROUP_PIC:

                                to_wbmux = spr_dat_pic;

                        `OR1200_SPR_GROUP_PM:

                                to_wbmux = spr_dat_pm;

                        `OR1200_SPR_GROUP_DMMU:

                                to_wbmux = spr_dat_dmmu;

                        `OR1200_SPR_GROUP_IMMU:

                                to_wbmux = spr_dat_immu;

                        `OR1200_SPR_GROUP_MAC:

                                to_wbmux = spr_dat_mac;

                        `OR1200_SPR_GROUP_FPU:

                                 to_wbmux = spr_dat_fpu;

                        default: //`OR1200_SPR_GROUP_DU:

                                to_wbmux = spr_dat_du;

                endcase

end

endmodule