cvw/wally-pipelined/src/privileged.sv

///////////////////////////////////////////
// exceptions.sv
//
// Written: David_Harris@hmc.edu 5 January 2021
// Modified: 
//
// Purpose: Implements the CSRs, Exceptions, and Privileged operations
//          See RISC-V Privileged Mode Specification 20190608 
// 
// A component of the Wally configurable RISC-V project.
// 
// Copyright (C) 2021 Harvey Mudd College & Oklahoma State University
//
// Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, 
// modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software 
// is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES 
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS 
// BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT 
// OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
///////////////////////////////////////////

`include "wally-config.vh"

module privileged (
  input  logic clk, reset,
  input  logic        CSRWriteM,
  input  logic [`XLEN-1:0] SrcAM,
  input  logic [31:0] InstrM,
  input  logic [`XLEN-1:0] PCM,
  output logic [`XLEN-1:0] CSRReadValM,
  output logic [`XLEN-1:0] PrivilegedNextPCM,
  output logic RetM, TrapM,
  input  logic InstrValidW, FloatRegWriteW, LoadStallD,
  input  logic PrivilegedM,
  input  logic InstrMisalignedFaultM, InstrAccessFaultF, IllegalIEUInstrFaultD,
  input  logic LoadMisalignedFaultM, LoadAccessFaultM,
  input  logic StoreMisalignedFaultM, StoreAccessFaultM,
  input  logic TimerIntM, ExtIntM, SwIntM,
  input  logic [`XLEN-1:0] InstrMisalignedAdrM, ALUResultM,
  input  logic [4:0]      SetFflagsM,
  output logic [2:0]      FRM_REGW,
  input  logic FlushD, FlushE, FlushM, StallD
);

  logic [1:0] NextPrivilegeModeM, PrivilegeModeW;

  logic [`XLEN-1:0] CauseM, NextFaultMtvalM;
  logic [`XLEN-1:0] MEPC_REGW, SEPC_REGW, UEPC_REGW, UTVEC_REGW, STVEC_REGW, MTVEC_REGW;
  logic [`XLEN-1:0] MEDELEG_REGW, MIDELEG_REGW, SEDELEG_REGW, SIDELEG_REGW;
//  logic [11:0]     MIP_REGW, SIP_REGW, UIP_REGW, MIE_REGW, SIE_REGW, UIE_REGW;

  logic uretM, sretM, mretM, ecallM, ebreakM, wfiM, sfencevmaM;
  logic IllegalCSRAccessM;
  logic  IllegalIEUInstrFaultE, IllegalIEUInstrFaultM;
  logic       InstrAccessFaultD, InstrAccessFaultE, InstrAccessFaultM;
  logic IllegalInstrFaultM;

  logic BreakpointFaultM, EcallFaultM;
  logic InstrPageFaultM, LoadPageFaultM, StorePageFaultM;
  logic MTrapM, STrapM, UTrapM; 

  logic [1:0] STATUS_MPP;
  logic       STATUS_SPP, STATUS_TSR;
  logic       STATUS_MIE, STATUS_SIE;
  logic [11:0] MIP_REGW, MIE_REGW;

  // track the current privilege level
  privilegeModeReg pmr(.*);

  // decode privileged instructions
  privilegeDecoder pmd(.InstrM(InstrM[31:20]), .*);
  
  // Extract exceptions by name and handle them 
  assign BreakpointFaultM = ebreakM; // could have other causes too
  assign EcallFaultM = ecallM;
  assign InstrPageFaultM = 0;
  assign LoadPageFaultM = 0;
  assign StorePageFaultM = 0;
  trap trap(.*);

  // Control and Status Registers
  csr csr(.*);

  // pipeline fault signals
  flopenrc #(1) faultregD(clk, reset, FlushD, ~StallD, InstrAccessFaultF, InstrAccessFaultD);
  floprc #(2) faultregE(clk, reset, FlushE,
                           {IllegalIEUInstrFaultD, InstrAccessFaultD}, // ** vs IllegalInstrFaultInD
                           {IllegalIEUInstrFaultE, InstrAccessFaultE});
  floprc #(2) faultregM(clk, reset, FlushM,
                         {IllegalIEUInstrFaultE, InstrAccessFaultE},
                         {IllegalIEUInstrFaultM, InstrAccessFaultM});


endmodule