/////////////////////////////////////////// // controller.sv // // Written: David_Harris@hmc.edu, Sarah.Harris@unlv.edu // Created: 9 January 2021 // Modified: // // Purpose: Top level controller module // // Documentation: RISC-V System on Chip Design Chapter 4 (Section 4.1.4, Figure 4.8, Table 4.5) // // A component of the CORE-V-WALLY configurable RISC-V project. // // Copyright (C) 2021-23 Harvey Mudd College & Oklahoma State University // // SPDX-License-Identifier: Apache-2.0 WITH SHL-2.1 // // Licensed under the Solderpad Hardware License v 2.1 (the “License”); you may not use this file // except in compliance with the License, or, at your option, the Apache License version 2.0. You // may obtain a copy of the License at // // https://solderpad.org/licenses/SHL-2.1/ // // Unless required by applicable law or agreed to in writing, any work distributed under the // License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, // either express or implied. See the License for the specific language governing permissions // and limitations under the License. //////////////////////////////////////////////////////////////////////////////////////////////// `include "wally-config.vh" module controller( input logic clk, reset, // Decode stage control signals input logic StallD, FlushD, // Stall, flush Decode stage input logic [31:0] InstrD, // Instruction in Decode stage output logic [2:0] ImmSrcD, // Type of immediate extension input logic IllegalIEUInstrFaultD, // Illegal IEU instruction output logic IllegalBaseInstrFaultD, // Illegal I-type instruction, or illegal RV32 access to upper 16 registers // Execute stage control signals input logic StallE, FlushE, // Stall, flush Execute stage input logic [1:0] FlagsE, // Comparison flags ({eq, lt}) input logic FWriteIntE, // Write integer register, coming from FPU controller output logic PCSrcE, // Select signal to choose next PC (for datapath and Hazard unit) output logic [2:0] ALUControlE, // ALU operation to perform output logic ALUSrcAE, ALUSrcBE, // ALU operands output logic ALUResultSrcE, // Selects result to pass on to Memory stage output logic [2:0] ALUSelectE, // ALU mux select signal output logic MemReadE, CSRReadE, // Instruction reads memory, reads a CSR (needed for Hazard unit) output logic [2:0] Funct3E, // Instruction's funct3 field output logic [6:0] Funct7E, // Instruction's funct7 field output logic IntDivE, // Integer divide output logic MDUE, // MDU (multiply/divide) operatio output logic W64E, // RV64 W-type operation output logic JumpE, // jump instruction output logic SCE, // Store Conditional instruction output logic BranchSignedE, // Branch comparison operands are signed (if it's a branch) output logic [3:0] BSelectE, // One-Hot encoding of if it's ZBA_ZBB_ZBC_ZBS instruction // Memory stage control signals input logic StallM, FlushM, // Stall, flush Memory stage output logic [1:0] MemRWM, // Mem read/write: MemRWM[1] = 1 for read, MemRWM[0] = 1 for write output logic CSRReadM, CSRWriteM, PrivilegedM, // CSR read, write, or privileged instruction output logic [1:0] AtomicM, // Atomic (AMO) instruction output logic [2:0] Funct3M, // Instruction's funct3 field output logic RegWriteM, // Instruction writes a register (needed for Hazard unit) output logic InvalidateICacheM, FlushDCacheM, // Invalidate I$, flush D$ output logic InstrValidD, InstrValidE, InstrValidM, // Instruction is valid output logic FWriteIntM, // FPU controller writes integer register file // Writeback stage control signals input logic StallW, FlushW, // Stall, flush Writeback stage output logic RegWriteW, IntDivW, // Instruction writes a register, is an integer divide output logic [2:0] ResultSrcW, // Select source of result to write back to register file // Stall during CSRs output logic CSRWriteFenceM, // CSR write or fence instruction; needs to flush the following instructions output logic StoreStallD // Store (memory write) causes stall ); logic [6:0] OpD; // Opcode in Decode stage logic [2:0] Funct3D; // Funct3 field in Decode stage logic [6:0] Funct7D; // Funct7 field in Decode stage logic [4:0] Rs1D; // Rs1 source register in Decode stage `define CTRLW 23 // pipelined control signals logic RegWriteD, RegWriteE; // RegWrite (register will be written) logic [2:0] ResultSrcD, ResultSrcE, ResultSrcM; // Select which result to write back to register file logic [1:0] MemRWD, MemRWE; // Store (write to memory) logic JumpD; // Jump instruction logic BranchD, BranchE; // Branch instruction logic ALUOpD; // 0 for address generation, 1 for all other operations (must use Funct3) logic [2:0] ALUControlD; // Determines ALU operation logic [2:0] ALUSelectD; // ALU mux select signal logic ALUSrcAD, ALUSrcBD; // ALU inputs logic ALUResultSrcD, W64D, MDUD; // ALU result, is RV64 W-type, is multiply/divide instruction logic CSRZeroSrcD; // Ignore setting and clearing zeros to CSR logic CSRReadD; // CSR read instruction logic [1:0] AtomicD; // Atomic (AMO) instruction logic FenceXD; // Fence instruction logic InvalidateICacheD, FlushDCacheD;// Invalidate I$, flush D$ logic CSRWriteD, CSRWriteE; // CSR write logic PrivilegedD, PrivilegedE; // Privileged instruction logic InvalidateICacheE, FlushDCacheE;// Invalidate I$, flush D$ logic [`CTRLW-1:0] ControlsD; // Main Instruction Decoder control signals logic SubArithD; // TRUE for R-type subtracts and sra, slt, sltu logic subD, sraD, sltD, sltuD; // Indicates if is one of these instructions logic BranchTakenE; // Branch is taken logic eqE, ltE; // Comparator outputs logic unused; logic BranchFlagE; // Branch flag to use (chosen between eq or lt) logic IEURegWriteE; // Register write logic IllegalERegAdrD; // RV32E attempts to write upper 16 registers logic [1:0] AtomicE; // Atomic instruction logic FenceD, FenceE, FenceM; // Fence instruction logic SFenceVmaD; // sfence.vma instruction logic IntDivM; // Integer divide instruction // Extract fields assign OpD = InstrD[6:0]; assign Funct3D = InstrD[14:12]; assign Funct7D = InstrD[31:25]; assign Rs1D = InstrD[19:15]; // Main Instruction Decoder always_comb case(OpD) // RegWrite_ImmSrc_ALUSrc_MemRW_ResultSrc_Branch_ALUOp_Jump_ALUResultSrc_W64_CSRRead_Privileged_Fence_MDU_Atomic_Illegal 7'b0000000: ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Illegal instruction 7'b0000011: ControlsD = `CTRLW'b1_000_01_10_001_0_0_0_0_0_0_0_0_0_00_0; // lw 7'b0000111: ControlsD = `CTRLW'b0_000_01_10_001_0_0_0_0_0_0_0_0_0_00_0; // flw - only legal if FP supported 7'b0001111: if (`ZIFENCEI_SUPPORTED) ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_1_0_00_0; // fence else ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_0; // fence treated as nop 7'b0010011: ControlsD = `CTRLW'b1_000_01_00_000_0_1_0_0_0_0_0_0_0_00_0; // I-type ALU 7'b0010111: ControlsD = `CTRLW'b1_100_11_00_000_0_0_0_0_0_0_0_0_0_00_0; // auipc 7'b0011011: if (`XLEN == 64) ControlsD = `CTRLW'b1_000_01_00_000_0_1_0_0_1_0_0_0_0_00_0; // IW-type ALU for RV64i else ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Non-implemented instruction 7'b0100011: ControlsD = `CTRLW'b0_001_01_01_000_0_0_0_0_0_0_0_0_0_00_0; // sw 7'b0100111: ControlsD = `CTRLW'b0_001_01_01_000_0_0_0_0_0_0_0_0_0_00_0; // fsw - only legal if FP supported 7'b0101111: if (`A_SUPPORTED) begin if (InstrD[31:27] == 5'b00010) ControlsD = `CTRLW'b1_000_00_10_001_0_0_0_0_0_0_0_0_0_01_0; // lr else if (InstrD[31:27] == 5'b00011) ControlsD = `CTRLW'b1_101_01_01_100_0_0_0_0_0_0_0_0_0_01_0; // sc else ControlsD = `CTRLW'b1_101_01_11_001_0_0_0_0_0_0_0_0_0_10_0; // amo end else ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Non-implemented instruction 7'b0110011: if (Funct7D == 7'b0000000 | Funct7D == 7'b0100000 | (Funct7D == 7'b0000101 & `ZBC_SUPPORTED)) ControlsD = `CTRLW'b1_000_00_00_000_0_1_0_0_0_0_0_0_0_00_0; // R-type else if (Funct7D == 7'b0000001 & `M_SUPPORTED) ControlsD = `CTRLW'b1_000_00_00_011_0_0_0_0_0_0_0_0_1_00_0; // Multiply/divide else ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Non-implemented instruction 7'b0110111: ControlsD = `CTRLW'b1_100_01_00_000_0_0_0_1_0_0_0_0_0_00_0; // lui 7'b0111011: if ((Funct7D == 7'b0000000 | Funct7D == 7'b0100000) & `XLEN == 64) ControlsD = `CTRLW'b1_000_00_00_000_0_1_0_0_1_0_0_0_0_00_0; // R-type W instructions for RV64i else if (Funct7D == 7'b0000001 & `M_SUPPORTED & `XLEN == 64) ControlsD = `CTRLW'b1_000_00_00_011_0_0_0_0_1_0_0_0_1_00_0; // W-type Multiply/Divide else ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // Non-implemented instruction 7'b1100011: ControlsD = `CTRLW'b0_010_11_00_000_1_0_0_0_0_0_0_0_0_00_0; // branches 7'b1100111: ControlsD = `CTRLW'b1_000_01_00_000_0_0_1_1_0_0_0_0_0_00_0; // jalr 7'b1101111: ControlsD = `CTRLW'b1_011_11_00_000_0_0_1_1_0_0_0_0_0_00_0; // jal 7'b1110011: if (`ZICSR_SUPPORTED) begin if (Funct3D == 3'b000) ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_1_0_0_00_0; // privileged; decoded further in priveleged modules else ControlsD = `CTRLW'b1_000_00_00_010_0_0_0_0_0_1_0_0_0_00_0; // csrs end else ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // non-implemented instruction default: ControlsD = `CTRLW'b0_000_00_00_000_0_0_0_0_0_0_0_0_0_00_1; // non-implemented instruction endcase // Unswizzle control bits // Squash control signals if coming from an illegal compressed instruction // On RV32E, can't write to upper 16 registers. Checking reads to upper 16 is more costly so disregard them. assign IllegalERegAdrD = `E_SUPPORTED & `ZICSR_SUPPORTED & ControlsD[`CTRLW-1] & InstrD[11]; assign IllegalBaseInstrFaultD = ControlsD[0] | IllegalERegAdrD; assign {RegWriteD, ImmSrcD, ALUSrcAD, ALUSrcBD, MemRWD, ResultSrcD, BranchD, ALUOpD, JumpD, ALUResultSrcD, W64D, CSRReadD, PrivilegedD, FenceXD, MDUD, AtomicD, unused} = IllegalIEUInstrFaultD ? `CTRLW'b0 : ControlsD; assign CSRZeroSrcD = InstrD[14] ? (InstrD[19:15] == 0) : (Rs1D == 0); // Is a CSR instruction using zero as the source? assign CSRWriteD = CSRReadD & !(CSRZeroSrcD & InstrD[13]); // Don't write if setting or clearing zeros assign SFenceVmaD = PrivilegedD & (InstrD[31:25] == 7'b0001001); assign FenceD = SFenceVmaD | FenceXD; // possible sfence.vma or fence.i // ALU Decoding is lazy, only using func7[5] to distinguish add/sub and srl/sra assign sltD = (Funct3D == 3'b010); assign sltuD = (Funct3D == 3'b011); assign subD = (Funct3D == 3'b000 & Funct7D[5] & OpD[5]); // OpD[5] needed to distinguish sub from addi assign sraD = (Funct3D == 3'b101 & Funct7D[5]); assign SubArithD = ALUOpD & (subD | sraD | sltD | sltuD | (`ZBS_SUPPORTED & BSelectE[0] & ALUSelectD == 3'b101)); // TRUE for R-type subtracts and sra, slt, sltu, bext assign ALUControlD = {W64D, SubArithD, ALUOpD}; if (`ZBS_SUPPORTED) begin: bitmanipi //change the conditional expression to OR any Z supported flags bmuctrl bmuctrl(.clk, .reset, .StallD, .FlushD, .InstrD, .ALUSelectD, .StallE, .FlushE, .Funct7E, .ALUSelectE, BSelectE); end else begin: bitmanipi assign ALUSelectD = Funct3D; assign ALUSelectE = Funct3E; assign BSelectE = 4'b000; assign Funct7E = 7'b0; end // Fences // Ordinary fence is presently a nop // fence.i flushes the D$ and invalidates the I$ if Zifencei is supported and I$ is implemented if (`ZIFENCEI_SUPPORTED & `ICACHE_SUPPORTED) begin:fencei logic FenceID; assign FenceID = FenceXD & (Funct3D == 3'b001); // is it a FENCE.I instruction? assign InvalidateICacheD = FenceID; assign FlushDCacheD = FenceID; end else begin:fencei assign InvalidateICacheD = 0; assign FlushDCacheD = 0; end // Decocde stage pipeline control register flopenrc #(1) controlregD(clk, reset, FlushD, ~StallD, 1'b1, InstrValidD); // Execute stage pipeline control register and logic flopenrc #(28) controlregE(clk, reset, FlushE, ~StallE, {RegWriteD, ResultSrcD, MemRWD, JumpD, BranchD, ALUControlD, ALUSrcAD, ALUSrcBD, ALUResultSrcD, CSRReadD, CSRWriteD, PrivilegedD, Funct3D, W64D, MDUD, AtomicD, InvalidateICacheD, FlushDCacheD, FenceD, InstrValidD}, {IEURegWriteE, ResultSrcE, MemRWE, JumpE, BranchE, ALUControlE, ALUSrcAE, ALUSrcBE, ALUResultSrcE, CSRReadE, CSRWriteE, PrivilegedE, Funct3E, W64E, MDUE, AtomicE, InvalidateICacheE, FlushDCacheE, FenceE, InstrValidE}); // Branch Logic // The comparator handles both signed and unsigned branches using BranchSignedE // Hence, only eq and lt flags are needed assign BranchSignedE = ~(Funct3E[2:1] == 2'b11); assign {eqE, ltE} = FlagsE; mux2 #(1) branchflagmux(eqE, ltE, Funct3E[2], BranchFlagE); assign BranchTakenE = BranchFlagE ^ Funct3E[0]; assign PCSrcE = JumpE | BranchE & BranchTakenE; // Other execute stage controller signals assign MemReadE = MemRWE[1]; assign SCE = (ResultSrcE == 3'b100); assign RegWriteE = IEURegWriteE | FWriteIntE; // IRF register writes could come from IEU or FPU controllers assign IntDivE = MDUE & Funct3E[2]; // Integer division operation // Memory stage pipeline control register flopenrc #(20) controlregM(clk, reset, FlushM, ~StallM, {RegWriteE, ResultSrcE, MemRWE, CSRReadE, CSRWriteE, PrivilegedE, Funct3E, FWriteIntE, AtomicE, InvalidateICacheE, FlushDCacheE, FenceE, InstrValidE, IntDivE}, {RegWriteM, ResultSrcM, MemRWM, CSRReadM, CSRWriteM, PrivilegedM, Funct3M, FWriteIntM, AtomicM, InvalidateICacheM, FlushDCacheM, FenceM, InstrValidM, IntDivM}); // Writeback stage pipeline control register flopenrc #(5) controlregW(clk, reset, FlushW, ~StallW, {RegWriteM, ResultSrcM, IntDivM}, {RegWriteW, ResultSrcW, IntDivW}); // Flush F, D, and E stages on a CSR write or Fence.I or SFence.VMA assign CSRWriteFenceM = CSRWriteM | FenceM; // assign CSRWriteFencePendingDEM = CSRWriteD | CSRWriteE | CSRWriteM | FenceD | FenceE | FenceM; // the synchronous DTIM cannot read immediately after write // a cache cannot read or write immediately after a write assign StoreStallD = MemRWE[0] & ((MemRWD[1] | (MemRWD[0] & `DCACHE_SUPPORTED)) | (|AtomicD)); endmodule