diff options
| -rw-r--r-- | rv64cpu/rtl/core/csr_unit.sv | 499 | ||||
| -rw-r--r-- | rv64cpu/rtl/core/include/csr_pkg.sv | 7 | ||||
| -rw-r--r-- | rv64cpu/rtl/core/richard_core.sv | 42 | ||||
| -rw-r--r-- | rv64cpu/tb/CMakeLists.txt | 20 | ||||
| -rw-r--r-- | rv64cpu/tb/unit/tb_csr.cc | 335 |
5 files changed, 893 insertions, 10 deletions
diff --git a/rv64cpu/rtl/core/csr_unit.sv b/rv64cpu/rtl/core/csr_unit.sv new file mode 100644 index 0000000..1749790 --- /dev/null +++ b/rv64cpu/rtl/core/csr_unit.sv @@ -0,0 +1,499 @@ +// Richard CPU +// Copyright (C) 2026 Richard Qin + +// This program is free software: you can redistribute it and/or modify +// it under the terms of the GNU General Public License as published by +// the Free Software Foundation, either version 3 of the License, or +// (at your option) any later version. + +// This program 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 General Public License for more details. + +// You should have received a copy of the GNU General Public License +// along with this program. If not, see <https://www.gnu.org/licenses/>. + +// File path: rtl/core/csr_unit.sv + +module csr_unit + import rv64_pkg::*; + import csr_pkg::*; +#( + parameter logic [XLEN-1:0] HART_ID = '0, + parameter logic [XLEN-1:0] VENDOR_ID = '0, + parameter logic [XLEN-1:0] ARCH_ID = '0, + parameter logic [XLEN-1:0] IMPL_ID = '0, + parameter logic [XLEN-1:0] MISA_VALUE = 64'h8000_0000_0050_112D +)( + input logic clk, + input logic rst, + input logic csr_req, + input logic [2:0] csr_op, + input logic [11:0] csr_addr, + input logic [XLEN-1:0] csr_rs1_data, + input logic trap_illegal_instr, + input logic trap_is_ecall, + input logic trap_is_ebreak, + input logic trap_is_mret, + input logic trap_is_sret, + input logic [XLEN-1:0] trap_epc, + output logic [XLEN-1:0] csr_rdata, + output logic [XLEN-1:0] csr_mstatus, + output logic [XLEN-1:0] csr_sstatus, + output logic [XLEN-1:0] csr_medeleg, + output logic [XLEN-1:0] csr_mideleg, + output logic [XLEN-1:0] csr_mtvec, + output logic [XLEN-1:0] csr_stvec, + output logic [XLEN-1:0] csr_mepc, + output logic [XLEN-1:0] csr_sepc, + output logic [XLEN-1:0] csr_satp, + output logic [1:0] csr_priv_mode, + output logic [XLEN-1:0] csr_trap_vector, + output logic csr_trap_to_s_mode, + output logic csr_illegal_access +); + + typedef enum logic [1:0] { + PRIV_MODE_U = 2'b00, + PRIV_MODE_S = 2'b01, + PRIV_MODE_M = 2'b11 + } priv_mode_t; + + localparam int MSTATUS_MIE_BIT = 3; + localparam int MSTATUS_MPIE_BIT = 7; + localparam int MSTATUS_MPP_LO = 11; + localparam int MSTATUS_MPP_HI = 12; + localparam int SSTATUS_SIE_BIT = 1; + localparam int SSTATUS_SPIE_BIT = 5; + localparam int SSTATUS_SPP_BIT = 8; + + // Machine-mode CSRs + logic [XLEN-1:0] mstatus_reg; + logic [XLEN-1:0] medeleg_reg; + logic [XLEN-1:0] mideleg_reg; + logic [XLEN-1:0] mie_reg; + logic [XLEN-1:0] mtvec_reg; + logic [XLEN-1:0] mcounteren_reg; + logic [XLEN-1:0] mscratch_reg; + logic [XLEN-1:0] mepc_reg; + logic [XLEN-1:0] mcause_reg; + logic [XLEN-1:0] mtval_reg; + logic [XLEN-1:0] mip_reg; + + // Supervisor-mode CSRs + logic [XLEN-1:0] sstatus_reg; + logic [XLEN-1:0] sie_reg; + logic [XLEN-1:0] stvec_reg; + logic [XLEN-1:0] scounteren_reg; + logic [XLEN-1:0] sscratch_reg; + logic [XLEN-1:0] sepc_reg; + logic [XLEN-1:0] scause_reg; + logic [XLEN-1:0] stval_reg; + logic [XLEN-1:0] sip_reg; + logic [XLEN-1:0] satp_reg; + + // Counters + logic [XLEN-1:0] mcycle_reg; + logic [XLEN-1:0] minstret_reg; + logic [XLEN-1:0] time_reg; + + // Floating-point CSRs + logic [4:0] fflags_reg; + logic [2:0] frm_reg; + + priv_mode_t priv_mode_q; + + logic [11:0] csr_addr_canonical; + logic is_write_cmd; + logic is_set_cmd; + logic is_clear_cmd; + logic has_non_zero_data; + logic csr_write_en; + logic trap_event; + logic [5:0] trap_cause_index; + logic trap_delegated_to_s; + logic [XLEN-1:0] trap_cause_value; + logic [XLEN-1:0] trap_vector_target; + logic [XLEN-1:0] trap_vector_q; + logic csr_addr_supported; + logic csr_write_illegal; + logic [XLEN-1:0] csr_read_data; + logic trap_to_s_q; + + // Canonicalize addresses, decode operations, and prepare CSR/trap metadata. + assign csr_addr_canonical = canonical_addr(csr_addr); + assign is_write_cmd = (csr_op == 3'b001) || (csr_op == 3'b101); + assign is_set_cmd = (csr_op == 3'b010) || (csr_op == 3'b110); + assign is_clear_cmd = (csr_op == 3'b011) || (csr_op == 3'b111); + assign has_non_zero_data = |csr_rs1_data; + assign csr_addr_supported = csr_is_supported(csr_addr_canonical); + assign csr_write_en = csr_req & csr_addr_supported & (is_write_cmd | ((is_set_cmd | is_clear_cmd) & has_non_zero_data)); + assign trap_event = trap_illegal_instr | trap_is_ecall | trap_is_ebreak; + assign trap_cause_value = compute_trap_cause(priv_mode_q, trap_illegal_instr, trap_is_ecall, trap_is_ebreak); + assign trap_cause_index = trap_cause_value[5:0]; + assign trap_delegated_to_s = trap_event && (priv_mode_q != PRIV_MODE_M) && medeleg_reg[trap_cause_index]; + assign trap_vector_target = trap_delegated_to_s ? stvec_reg : mtvec_reg; + assign csr_read_data = read_csr(csr_addr_canonical); + assign csr_rdata = csr_read_data; + assign csr_mstatus = mstatus_reg; + assign csr_sstatus = sstatus_reg; + assign csr_medeleg = medeleg_reg; + assign csr_mideleg = mideleg_reg; + assign csr_mtvec = mtvec_reg; + assign csr_stvec = stvec_reg; + assign csr_mepc = mepc_reg; + assign csr_sepc = sepc_reg; + assign csr_satp = satp_reg; + assign csr_priv_mode = priv_mode_q; + assign csr_trap_vector = trap_vector_q; + assign csr_trap_to_s_mode = trap_to_s_q; + assign csr_write_illegal = (csr_req && (is_write_cmd || is_set_cmd || is_clear_cmd) && !csr_is_writable(csr_addr_canonical)); + assign csr_illegal_access = csr_req && (!csr_addr_supported || csr_write_illegal); + + // Main CSR state machine: counts cycles, processes CSR writes, and reacts to traps/returns. + always_ff @(posedge clk) begin + if (rst) begin + mstatus_reg <= '0; + medeleg_reg <= '0; + mideleg_reg <= '0; + mie_reg <= '0; + mtvec_reg <= '0; + mcounteren_reg <= '0; + mscratch_reg <= '0; + mepc_reg <= '0; + mcause_reg <= '0; + mtval_reg <= '0; + mip_reg <= '0; + sstatus_reg <= '0; + sie_reg <= '0; + stvec_reg <= '0; + scounteren_reg <= '0; + sscratch_reg <= '0; + sepc_reg <= '0; + scause_reg <= '0; + stval_reg <= '0; + sip_reg <= '0; + satp_reg <= '0; + mcycle_reg <= '0; + minstret_reg <= '0; + time_reg <= '0; + fflags_reg <= '0; + frm_reg <= '0; + priv_mode_q <= PRIV_MODE_M; + trap_vector_q <= '0; + trap_to_s_q <= 1'b0; + end else begin + mcycle_reg <= mcycle_reg + 64'd1; + time_reg <= time_reg + 64'd1; + if (!trap_event) begin + minstret_reg <= minstret_reg + 64'd1; + end + + if (csr_write_en && csr_is_writable(csr_addr_canonical)) begin + unique case (csr_addr_canonical) + CSR_MSTATUS: begin + logic [XLEN-1:0] next_val; + next_val = csr_write_next(mstatus_reg, csr_rs1_data, csr_op); + mstatus_reg <= next_val; + sstatus_reg <= mirror_mstatus_to_sstatus(sstatus_reg, next_val); + end + CSR_MEDELEG: medeleg_reg <= csr_write_next(medeleg_reg, csr_rs1_data, csr_op); + CSR_MIDELEG: mideleg_reg <= csr_write_next(mideleg_reg, csr_rs1_data, csr_op); + CSR_MIE: mie_reg <= csr_write_next(mie_reg, csr_rs1_data, csr_op); + CSR_MTVEC: mtvec_reg <= csr_write_next(mtvec_reg, csr_rs1_data, csr_op); + CSR_MSCRATCH: mscratch_reg <= csr_write_next(mscratch_reg, csr_rs1_data, csr_op); + CSR_MEPC: mepc_reg <= csr_write_next(mepc_reg, csr_rs1_data, csr_op); + CSR_MCAUSE: mcause_reg <= csr_write_next(mcause_reg, csr_rs1_data, csr_op); + CSR_MTVAL: mtval_reg <= csr_write_next(mtval_reg, csr_rs1_data, csr_op); + CSR_MIP: mip_reg <= csr_write_next(mip_reg, csr_rs1_data, csr_op); + CSR_MCOUNTEREN: mcounteren_reg <= csr_write_next(mcounteren_reg, csr_rs1_data, csr_op); + CSR_SSTATUS: begin + logic [XLEN-1:0] next_sstatus; + next_sstatus = csr_write_next(sstatus_reg, csr_rs1_data, csr_op); + sstatus_reg <= next_sstatus; + mstatus_reg <= apply_sstatus_to_mstatus(mstatus_reg, next_sstatus); + end + CSR_SIE: sie_reg <= csr_write_next(sie_reg, csr_rs1_data, csr_op); + CSR_STVEC: stvec_reg <= csr_write_next(stvec_reg, csr_rs1_data, csr_op); + CSR_SCOUNTEREN: scounteren_reg <= csr_write_next(scounteren_reg, csr_rs1_data, csr_op); + CSR_SSCRATCH: sscratch_reg <= csr_write_next(sscratch_reg, csr_rs1_data, csr_op); + CSR_SEPC: sepc_reg <= csr_write_next(sepc_reg, csr_rs1_data, csr_op); + CSR_SCAUSE: scause_reg <= csr_write_next(scause_reg, csr_rs1_data, csr_op); + CSR_STVAL: stval_reg <= csr_write_next(stval_reg, csr_rs1_data, csr_op); + CSR_SIP: sip_reg <= csr_write_next(sip_reg, csr_rs1_data, csr_op); + CSR_SATP: satp_reg <= csr_write_next(satp_reg, csr_rs1_data, csr_op); + CSR_MCYCLE: mcycle_reg <= csr_write_next(mcycle_reg, csr_rs1_data, csr_op); + CSR_MINSTRET: minstret_reg <= csr_write_next(minstret_reg, csr_rs1_data, csr_op); + CSR_FFLAGS: begin + logic [XLEN-1:0] next_flags; + next_flags = csr_write_next({{(XLEN-5){1'b0}}, fflags_reg}, csr_rs1_data, csr_op); + fflags_reg <= next_flags[4:0]; + end + CSR_FRM: begin + logic [XLEN-1:0] next_frm; + next_frm = csr_write_next({{(XLEN-3){1'b0}}, frm_reg}, csr_rs1_data, csr_op); + frm_reg <= next_frm[2:0]; + end + CSR_FCSR: begin + logic [XLEN-1:0] next_fcsr; + next_fcsr = csr_write_next(compose_fcsr(), csr_rs1_data, csr_op); + fflags_reg <= next_fcsr[4:0]; + frm_reg <= next_fcsr[7:5]; + end + default: ; + endcase + end + + if (trap_event) begin + trap_vector_q <= trap_vector_target; + trap_to_s_q <= trap_delegated_to_s; + // Update privilege-specific CSRs based on whether the trap was delegated. + if (trap_delegated_to_s) begin + logic [XLEN-1:0] next_sstatus; + next_sstatus = sstatus_reg; + next_sstatus[SSTATUS_SPIE_BIT] = sstatus_reg[SSTATUS_SIE_BIT]; + next_sstatus[SSTATUS_SIE_BIT] = 1'b0; + next_sstatus[SSTATUS_SPP_BIT] = (priv_mode_q == PRIV_MODE_S); + sstatus_reg <= next_sstatus; + mstatus_reg <= apply_sstatus_to_mstatus(mstatus_reg, next_sstatus); + sepc_reg <= trap_epc; + scause_reg <= trap_cause_value; + stval_reg <= trap_illegal_instr ? trap_epc : '0; + priv_mode_q <= PRIV_MODE_S; + end else begin + logic [XLEN-1:0] next_mstatus; + next_mstatus = mstatus_reg; + next_mstatus[MSTATUS_MPIE_BIT] = mstatus_reg[MSTATUS_MIE_BIT]; + next_mstatus[MSTATUS_MIE_BIT] = 1'b0; + next_mstatus[MSTATUS_MPP_HI:MSTATUS_MPP_LO] = encode_priv_mode(priv_mode_q); + mstatus_reg <= next_mstatus; + sstatus_reg <= mirror_mstatus_to_sstatus(sstatus_reg, next_mstatus); + mepc_reg <= trap_epc; + mcause_reg <= trap_cause_value; + mtval_reg <= trap_illegal_instr ? trap_epc : '0; + priv_mode_q <= PRIV_MODE_M; + end + end else begin + if (trap_is_mret) begin + priv_mode_t return_mode; + logic [XLEN-1:0] next_mstatus; + return_mode = decode_priv_mode(mstatus_reg[MSTATUS_MPP_HI:MSTATUS_MPP_LO]); + next_mstatus = mstatus_reg; + next_mstatus[MSTATUS_MIE_BIT] = mstatus_reg[MSTATUS_MPIE_BIT]; + next_mstatus[MSTATUS_MPIE_BIT] = 1'b1; + next_mstatus[MSTATUS_MPP_HI:MSTATUS_MPP_LO] = encode_priv_mode(PRIV_MODE_U); + mstatus_reg <= next_mstatus; + sstatus_reg <= mirror_mstatus_to_sstatus(sstatus_reg, next_mstatus); + priv_mode_q <= return_mode; + end + + if (trap_is_sret) begin + logic [XLEN-1:0] next_sstatus; + next_sstatus = sstatus_reg; + next_sstatus[SSTATUS_SIE_BIT] = sstatus_reg[SSTATUS_SPIE_BIT]; + next_sstatus[SSTATUS_SPIE_BIT] = 1'b1; + next_sstatus[SSTATUS_SPP_BIT] = 1'b0; + sstatus_reg <= next_sstatus; + mstatus_reg <= apply_sstatus_to_mstatus(mstatus_reg, next_sstatus); + priv_mode_q <= (sstatus_reg[SSTATUS_SPP_BIT]) ? PRIV_MODE_S : PRIV_MODE_U; + end + end + end + end + + // Map CSR aliases (cycle/instret) to their canonical machine addresses. + function automatic logic [11:0] canonical_addr(input logic [11:0] addr); + case (addr) + CSR_CYCLE: canonical_addr = CSR_MCYCLE; + CSR_INSTRET: canonical_addr = CSR_MINSTRET; + default: canonical_addr = addr; + endcase + endfunction + + // Apply the CSR op semantics (write/set/clear) for a single register. + function automatic logic [XLEN-1:0] csr_write_next( + input logic [XLEN-1:0] current_val, + input logic [XLEN-1:0] write_val, + input logic [2:0] op_code + ); + logic [XLEN-1:0] next_val; + unique case (op_code) + 3'b001, 3'b101: next_val = write_val; // CSRRW / CSRRWI + 3'b010, 3'b110: next_val = current_val | write_val; // CSRRS / CSRRSI + 3'b011, 3'b111: next_val = current_val & ~write_val; // CSRRC / CSRRCI + default: next_val = current_val; + endcase + return next_val; + endfunction + + function automatic bit csr_is_writable(input logic [11:0] addr); + case (addr) + CSR_MISA, + CSR_MVENDORID, + CSR_MARCHID, + CSR_MIMPID, + CSR_MHARTID, + CSR_TIME: csr_is_writable = 1'b0; + default: csr_is_writable = 1'b1; + endcase + endfunction + + function automatic bit csr_is_supported(input logic [11:0] addr); + bit supported; + unique case (addr) + CSR_MSTATUS, + CSR_MISA, + CSR_MEDELEG, + CSR_MIDELEG, + CSR_MIE, + CSR_MTVEC, + CSR_MSCRATCH, + CSR_MEPC, + CSR_MCAUSE, + CSR_MTVAL, + CSR_MIP, + CSR_MCOUNTEREN, + CSR_MVENDORID, + CSR_MARCHID, + CSR_MIMPID, + CSR_MHARTID, + CSR_SSTATUS, + CSR_SIE, + CSR_STVEC, + CSR_SCOUNTEREN, + CSR_SSCRATCH, + CSR_SEPC, + CSR_SCAUSE, + CSR_STVAL, + CSR_SIP, + CSR_SATP, + CSR_MCYCLE, + CSR_MINSTRET, + CSR_CYCLE, + CSR_INSTRET, + CSR_TIME, + CSR_FFLAGS, + CSR_FRM, + CSR_FCSR: + supported = 1'b1; + default: + supported = 1'b0; + endcase + return supported; + endfunction + + function automatic logic [XLEN-1:0] apply_sstatus_to_mstatus( + input logic [XLEN-1:0] mstatus_cur, + input logic [XLEN-1:0] sstatus_val + ); + logic [XLEN-1:0] next_val; + next_val = mstatus_cur; + next_val[SSTATUS_SIE_BIT] = sstatus_val[SSTATUS_SIE_BIT]; + next_val[SSTATUS_SPIE_BIT] = sstatus_val[SSTATUS_SPIE_BIT]; + next_val[SSTATUS_SPP_BIT] = sstatus_val[SSTATUS_SPP_BIT]; + return next_val; + endfunction + + function automatic logic [XLEN-1:0] mirror_mstatus_to_sstatus( + input logic [XLEN-1:0] sstatus_cur, + input logic [XLEN-1:0] mstatus_val + ); + logic [XLEN-1:0] next_val; + next_val = sstatus_cur; + next_val[SSTATUS_SIE_BIT] = mstatus_val[SSTATUS_SIE_BIT]; + next_val[SSTATUS_SPIE_BIT] = mstatus_val[SSTATUS_SPIE_BIT]; + next_val[SSTATUS_SPP_BIT] = mstatus_val[SSTATUS_SPP_BIT]; + return next_val; + endfunction + + // Pack the discrete FP status bits into the architectural FCSR layout. + function automatic logic [XLEN-1:0] compose_fcsr(); + logic [XLEN-1:0] value; + value = '0; + value[4:0] = fflags_reg; + value[7:5] = frm_reg; + return value; + endfunction + + function automatic priv_mode_t decode_priv_mode(input logic [1:0] encoded); + case (encoded) + 2'b00: decode_priv_mode = PRIV_MODE_U; + 2'b01: decode_priv_mode = PRIV_MODE_S; + default: decode_priv_mode = PRIV_MODE_M; + endcase + endfunction + + function automatic logic [1:0] encode_priv_mode(input priv_mode_t mode); + case (mode) + PRIV_MODE_U: encode_priv_mode = 2'b00; + PRIV_MODE_S: encode_priv_mode = 2'b01; + default: encode_priv_mode = 2'b11; + endcase + endfunction + + function automatic logic [XLEN-1:0] compute_trap_cause( + input priv_mode_t mode, + input logic illegal_instr, + input logic is_ecall, + input logic is_ebreak + ); + logic [XLEN-1:0] cause_val; + cause_val = '0; + if (illegal_instr) begin + cause_val = EXC_INST_ILLEGAL; + end else if (is_ebreak) begin + cause_val = EXC_BREAKPOINT; + end else if (is_ecall) begin + case (mode) + PRIV_MODE_U: cause_val = EXC_ECALL_FROM_U; + PRIV_MODE_S: cause_val = EXC_ECALL_FROM_S; + default: cause_val = EXC_ECALL_FROM_M; + endcase + end + return cause_val; + endfunction + + function automatic logic [XLEN-1:0] read_csr(input logic [11:0] addr); + logic [XLEN-1:0] data_out; + unique case (addr) + CSR_FFLAGS: data_out = {{(XLEN-5){1'b0}}, fflags_reg}; + CSR_FRM: data_out = {{(XLEN-3){1'b0}}, frm_reg}; + CSR_FCSR: data_out = compose_fcsr(); + CSR_MSTATUS: data_out = mstatus_reg; + CSR_MISA: data_out = MISA_VALUE; + CSR_MEDELEG: data_out = medeleg_reg; + CSR_MIDELEG: data_out = mideleg_reg; + CSR_MIE: data_out = mie_reg; + CSR_MTVEC: data_out = mtvec_reg; + CSR_MSCRATCH: data_out = mscratch_reg; + CSR_MEPC: data_out = mepc_reg; + CSR_MCAUSE: data_out = mcause_reg; + CSR_MTVAL: data_out = mtval_reg; + CSR_MIP: data_out = mip_reg; + CSR_MCOUNTEREN: data_out = mcounteren_reg; + CSR_MVENDORID: data_out = VENDOR_ID; + CSR_MARCHID: data_out = ARCH_ID; + CSR_MIMPID: data_out = IMPL_ID; + CSR_MHARTID: data_out = HART_ID; + CSR_SSTATUS: data_out = sstatus_reg; + CSR_SIE: data_out = sie_reg; + CSR_STVEC: data_out = stvec_reg; + CSR_SCOUNTEREN: data_out = scounteren_reg; + CSR_SSCRATCH: data_out = sscratch_reg; + CSR_SEPC: data_out = sepc_reg; + CSR_SCAUSE: data_out = scause_reg; + CSR_STVAL: data_out = stval_reg; + CSR_SIP: data_out = sip_reg; + CSR_SATP: data_out = satp_reg; + CSR_MCYCLE: data_out = mcycle_reg; + CSR_MINSTRET: data_out = minstret_reg; + CSR_CYCLE: data_out = mcycle_reg; + CSR_INSTRET: data_out = minstret_reg; + CSR_TIME: data_out = time_reg; + default: data_out = '0; + endcase + return data_out; + endfunction + +endmodule diff --git a/rv64cpu/rtl/core/include/csr_pkg.sv b/rv64cpu/rtl/core/include/csr_pkg.sv index 53165c9..a225da2 100644 --- a/rv64cpu/rtl/core/include/csr_pkg.sv +++ b/rv64cpu/rtl/core/include/csr_pkg.sv @@ -28,6 +28,13 @@ package csr_pkg; } csr_op_t; // --------------------------------- + // Floating-Point CSRs + // --------------------------------- + localparam logic [11:0] CSR_FFLAGS = 12'h001; // Floating-Point accrued exception flags + localparam logic [11:0] CSR_FRM = 12'h002; // Floating-Point dynamic rounding mode + localparam logic [11:0] CSR_FCSR = 12'h003; // Combined fflags/frm register + + // --------------------------------- // Machine Mode CSRs (M-Mode) // --------------------------------- localparam logic [11:0] CSR_MVENDORID = 12'hF11; // Vendor ID diff --git a/rv64cpu/rtl/core/richard_core.sv b/rv64cpu/rtl/core/richard_core.sv index 5b4acbc..ae73e77 100644 --- a/rv64cpu/rtl/core/richard_core.sv +++ b/rv64cpu/rtl/core/richard_core.sv @@ -154,6 +154,19 @@ module richard_core logic [11:0] csr_addr; logic [XLEN-1:0] csr_rs1_data; logic [XLEN-1:0] csr_rdata; // Result from CSR unit + logic [1:0] csr_priv_mode_cur; + logic [XLEN-1:0] csr_mtvec_base; + logic [XLEN-1:0] csr_stvec_base; + logic [XLEN-1:0] csr_mstatus_value; + logic [XLEN-1:0] csr_sstatus_value; + logic [XLEN-1:0] csr_medeleg_value; + logic [XLEN-1:0] csr_mideleg_value; + logic [XLEN-1:0] csr_mepc_value; + logic [XLEN-1:0] csr_sepc_value; + logic [XLEN-1:0] csr_satp_value; + logic [XLEN-1:0] csr_trap_vector_value; + logic csr_trap_to_s_mode_flag; + logic csr_illegal_access_flag; // (11) Exception / Trap bus logic trap_illegal_instr, trap_is_ecall, trap_is_ebreak, trap_is_mret, trap_is_sret; @@ -551,6 +564,33 @@ module richard_core .trap_epc (trap_epc) ); - assign csr_rdata = 64'b0; + csr_unit u_csr_unit ( + .clk (clk), + .rst (rst), + .csr_req (csr_req), + .csr_op (csr_op), + .csr_addr (csr_addr), + .csr_rs1_data (csr_rs1_data), + .trap_illegal_instr (trap_illegal_instr), + .trap_is_ecall (trap_is_ecall), + .trap_is_ebreak (trap_is_ebreak), + .trap_is_mret (trap_is_mret), + .trap_is_sret (trap_is_sret), + .trap_epc (trap_epc), + .csr_rdata (csr_rdata), + .csr_mstatus (csr_mstatus_value), + .csr_sstatus (csr_sstatus_value), + .csr_medeleg (csr_medeleg_value), + .csr_mideleg (csr_mideleg_value), + .csr_mtvec (csr_mtvec_base), + .csr_stvec (csr_stvec_base), + .csr_mepc (csr_mepc_value), + .csr_sepc (csr_sepc_value), + .csr_satp (csr_satp_value), + .csr_priv_mode (csr_priv_mode_cur), + .csr_trap_vector (csr_trap_vector_value), + .csr_trap_to_s_mode (csr_trap_to_s_mode_flag), + .csr_illegal_access (csr_illegal_access_flag) + ); endmodule diff --git a/rv64cpu/tb/CMakeLists.txt b/rv64cpu/tb/CMakeLists.txt index 1b6173a..48a4185 100644 --- a/rv64cpu/tb/CMakeLists.txt +++ b/rv64cpu/tb/CMakeLists.txt @@ -160,15 +160,15 @@ add_verilator_target( TB_SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/unit/tb_hazard_unit.cc ) # -# add_verilator_target( -# NAME tb_csr -# TOP_MODULE csr_unit -# SOURCES ${RTL_CORE_DIR}/include/rv64_pkg.sv -# ${RTL_CORE_DIR}/include/csr_pkg.sv -# ${RTL_CORE_DIR}/csr_unit.sv -# INCLUDE_DIRS ${RTL_COMMON_INCLUDES} -# TB_SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/unit/tb_csr.cc -# ) +add_verilator_target( + NAME tb_csr + TOP_MODULE csr_unit + SOURCES ${RTL_CORE_DIR}/include/rv64_pkg.sv + ${RTL_CORE_DIR}/include/csr_pkg.sv + ${RTL_CORE_DIR}/csr_unit.sv + INCLUDE_DIRS ${RTL_COMMON_INCLUDES} + TB_SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/unit/tb_csr.cc +) # ═══════════════════════════════════════════════════════════════════════════════════ # Core Integration Test @@ -192,6 +192,8 @@ add_verilator_target( ${RTL_CORE_DIR}/mem_wb_reg.sv ${RTL_CORE_DIR}/wb_stage.sv ${RTL_CORE_DIR}/hazard_unit.sv + ${RTL_CORE_DIR}/include/csr_pkg.sv + ${RTL_CORE_DIR}/csr_unit.sv ${RTL_CORE_DIR}/richard_core.sv INCLUDE_DIRS ${RTL_COMMON_INCLUDES} TB_SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/core/tb_core.cc diff --git a/rv64cpu/tb/unit/tb_csr.cc b/rv64cpu/tb/unit/tb_csr.cc new file mode 100644 index 0000000..95d6be7 --- /dev/null +++ b/rv64cpu/tb/unit/tb_csr.cc @@ -0,0 +1,335 @@ +// Richard CPU +// Copyright (C) 2026 Richard Qin +// +// This program is free software: you can redistribute it and/or modify +// it under the terms of the GNU General Public License as published by +// the Free Software Foundation, either version 3 of the License, or +// (at your option) any later version. +// +// This program 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 General Public License for more details. +// +// You should have received a copy of the GNU General Public License +// along with this program. If not, see <https://www.gnu.org/licenses/>. + +// File path: tb/unit/tb_csr.cc +// Description: CSR unit testbench + +#include <cassert> +#include <cstdint> +#include <iostream> +#include <verilated.h> + +#include "Vcsr_unit.h" + +namespace { +constexpr uint32_t CSR_OP_WRITE = 0b001; +constexpr uint32_t CSR_OP_SET = 0b010; +constexpr uint32_t CSR_OP_CLEAR = 0b011; + +constexpr uint16_t CSR_MSTATUS = 0x300; +constexpr uint16_t CSR_MISA = 0x301; +constexpr uint16_t CSR_MEDELEG = 0x302; +constexpr uint16_t CSR_MIDELEG = 0x303; +constexpr uint16_t CSR_MIE = 0x304; +constexpr uint16_t CSR_MTVEC = 0x305; +constexpr uint16_t CSR_MCOUNTEREN= 0x306; +constexpr uint16_t CSR_MSCRATCH = 0x340; +constexpr uint16_t CSR_MEPC = 0x341; +constexpr uint16_t CSR_MCAUSE = 0x342; +constexpr uint16_t CSR_MTVAL = 0x343; +constexpr uint16_t CSR_MCYCLE = 0xB00; +constexpr uint16_t CSR_MINSTRET = 0xB02; +constexpr uint16_t CSR_SSTATUS = 0x100; +constexpr uint16_t CSR_SIE = 0x104; +constexpr uint16_t CSR_STVEC = 0x105; +constexpr uint16_t CSR_SCOUNTEREN= 0x106; +constexpr uint16_t CSR_SSCRATCH = 0x140; +constexpr uint16_t CSR_SEPC = 0x141; +constexpr uint16_t CSR_SCAUSE = 0x142; +constexpr uint16_t CSR_STVAL = 0x143; +constexpr uint16_t CSR_SIP = 0x144; +constexpr uint16_t CSR_SATP = 0x180; +constexpr uint16_t CSR_CYCLE = 0xC00; +constexpr uint16_t CSR_INSTRET = 0xC02; +constexpr uint16_t CSR_FFLAGS = 0x001; +constexpr uint16_t CSR_FRM = 0x002; +constexpr uint16_t CSR_FCSR = 0x003; + +constexpr uint64_t EXC_INST_ILLEGAL = 2ULL; +constexpr uint64_t EXC_ECALL_FROM_U = 8ULL; +constexpr uint64_t EXC_ECALL_FROM_S = 9ULL; + +constexpr int MSTATUS_MIE_BIT = 3; +constexpr int MSTATUS_MPIE_BIT = 7; +constexpr int MSTATUS_MPP_LO = 11; +constexpr int MSTATUS_MPP_HI = 12; +constexpr int SSTATUS_SIE_BIT = 1; +constexpr int SSTATUS_SPIE_BIT = 5; +constexpr int SSTATUS_SPP_BIT = 8; + +constexpr uint64_t PRIV_ENCODE_U = 0ULL; +constexpr uint64_t PRIV_ENCODE_S = 1ULL; +constexpr uint64_t PRIV_ENCODE_M = 3ULL; +} + +void tick(Vcsr_unit* dut) { + dut->clk = 0; + dut->eval(); + dut->clk = 1; + dut->eval(); + dut->clk = 0; + dut->eval(); +} + +void drive_defaults(Vcsr_unit* dut) { + dut->clk = 0; + dut->rst = 0; + dut->csr_req = 0; + dut->csr_op = 0; + dut->csr_addr = 0; + dut->csr_rs1_data = 0; + dut->trap_illegal_instr = 0; + dut->trap_is_ecall = 0; + dut->trap_is_ebreak = 0; + dut->trap_is_mret = 0; + dut->trap_is_sret = 0; + dut->trap_epc = 0; +} + +void apply_reset(Vcsr_unit* dut) { + dut->rst = 1; + tick(dut); + dut->rst = 0; + tick(dut); +} + +void clear_trap_lines(Vcsr_unit* dut) { + dut->trap_illegal_instr = 0; + dut->trap_is_ecall = 0; + dut->trap_is_ebreak = 0; + dut->trap_is_mret = 0; + dut->trap_is_sret = 0; + dut->trap_epc = 0; +} + +uint64_t read_csr(Vcsr_unit* dut, uint16_t addr) { + dut->csr_addr = addr; + dut->csr_req = 0; + dut->csr_op = 0; + dut->csr_rs1_data = 0; + dut->eval(); + return dut->csr_rdata; +} + +void csr_op(Vcsr_unit* dut, uint16_t addr, uint32_t op, uint64_t data) { + dut->csr_addr = addr; + dut->csr_op = op; + dut->csr_rs1_data = data; + dut->csr_req = 1; + tick(dut); + dut->csr_req = 0; + dut->csr_op = 0; + dut->csr_rs1_data = 0; + dut->csr_addr = 0; +} + +void advance_cycles(Vcsr_unit* dut, int cycles) { + for (int i = 0; i < cycles; ++i) { + tick(dut); + } +} + +void force_priv_mode_via_mret(Vcsr_unit* dut, uint64_t encoded_mode) { + uint64_t mstatus = read_csr(dut, CSR_MSTATUS); + mstatus &= ~(0x3ULL << MSTATUS_MPP_LO); + mstatus |= (encoded_mode << MSTATUS_MPP_LO); + csr_op(dut, CSR_MSTATUS, CSR_OP_WRITE, mstatus); + dut->trap_is_mret = 1; + tick(dut); + dut->trap_is_mret = 0; +} + +int main(int argc, char** argv) { + Verilated::commandArgs(argc, argv); + Vcsr_unit* dut = new Vcsr_unit; + + drive_defaults(dut); + apply_reset(dut); + clear_trap_lines(dut); + + std::cout << "----------------------------------\n"; + std::cout << " CSR Unit Testbench\n"; + std::cout << "----------------------------------\n"; + + // Reset sanity + assert(read_csr(dut, CSR_MSTATUS) == 0); + assert(read_csr(dut, CSR_MIE) == 0); + assert(read_csr(dut, CSR_MEPC) == 0); + assert(read_csr(dut, CSR_SSTATUS) == 0); + assert(read_csr(dut, CSR_SATP) == 0); + std::cout << "[PASS] Reset clears CSR state" << std::endl; + + // CSRRW basic write + csr_op(dut, CSR_MTVEC, CSR_OP_WRITE, 0x1020ULL); + assert(read_csr(dut, CSR_MTVEC) == 0x1020ULL); + csr_op(dut, CSR_MSCRATCH, CSR_OP_WRITE, 0xCAFEBABEULL); + assert(read_csr(dut, CSR_MSCRATCH) == 0xCAFEBABEULL); + std::cout << "[PASS] CSRRW updates mutable CSRs" << std::endl; + + // CSRRS / CSRRC behavior + csr_op(dut, CSR_MIE, CSR_OP_WRITE, 0); + csr_op(dut, CSR_MIE, CSR_OP_SET, 0xBuLL); + assert(read_csr(dut, CSR_MIE) == 0xBuLL); + csr_op(dut, CSR_MIE, CSR_OP_CLEAR, 0x3ULL); + assert(read_csr(dut, CSR_MIE) == 0x8ULL); + csr_op(dut, CSR_MIE, CSR_OP_SET, 0x0ULL); + assert(read_csr(dut, CSR_MIE) == 0x8ULL); + std::cout << "[PASS] CSRRS/CSRRC honor masks and ignore zero data" << std::endl; + + // Read-only CSRs ignore write attempts + const uint64_t misa_before = read_csr(dut, CSR_MISA); + csr_op(dut, CSR_MISA, CSR_OP_WRITE, 0ULL); + assert(read_csr(dut, CSR_MISA) == misa_before); + std::cout << "[PASS] Read-only CSRs reject writes" << std::endl; + + // Canonical aliases for cycle/minstret + csr_op(dut, CSR_CYCLE, CSR_OP_WRITE, 0x40ULL); + assert(read_csr(dut, CSR_MCYCLE) == 0x40ULL); + advance_cycles(dut, 5); + assert(read_csr(dut, CSR_MCYCLE) == 0x45ULL); + const uint64_t instret_before = read_csr(dut, CSR_MINSTRET); + advance_cycles(dut, 3); + assert(read_csr(dut, CSR_MINSTRET) == instret_before + 3); + std::cout << "[PASS] Cycle/instret counters tick correctly" << std::endl; + + // Trap should freeze minstret for that cycle + uint64_t mstatus_cfg = read_csr(dut, CSR_MSTATUS) | (1ULL << MSTATUS_MIE_BIT); + csr_op(dut, CSR_MSTATUS, CSR_OP_WRITE, mstatus_cfg); + const uint64_t instret_pre_trap = read_csr(dut, CSR_MINSTRET); + dut->trap_illegal_instr = 1; + dut->trap_epc = 0xDEADULL; + tick(dut); + dut->trap_illegal_instr = 0; + dut->trap_epc = 0; + assert(read_csr(dut, CSR_MINSTRET) == instret_pre_trap); + advance_cycles(dut, 1); + assert(read_csr(dut, CSR_MINSTRET) == instret_pre_trap + 1); + std::cout << "[PASS] Trap cycle does not increment minstret" << std::endl; + + // Trap bookkeeping for illegal instruction + assert(read_csr(dut, CSR_MEPC) == 0xDEADULL); + assert(read_csr(dut, CSR_MCAUSE) == EXC_INST_ILLEGAL); + assert(read_csr(dut, CSR_MTVAL) == 0xDEADULL); + const uint64_t mstatus_after_trap = read_csr(dut, CSR_MSTATUS); + assert(((mstatus_after_trap >> MSTATUS_MIE_BIT) & 1ULL) == 0ULL); + assert(((mstatus_after_trap >> MSTATUS_MPIE_BIT) & 1ULL) == 1ULL); + assert(((mstatus_after_trap >> MSTATUS_MPP_LO) & 0x3ULL) == PRIV_ENCODE_M); + std::cout << "[PASS] Illegal trap updates mepc/mcause/mtval/mstatus" << std::endl; + + // mret restore flow + dut->trap_is_mret = 1; + tick(dut); + dut->trap_is_mret = 0; + const uint64_t mstatus_after_mret = read_csr(dut, CSR_MSTATUS); + assert(((mstatus_after_mret >> MSTATUS_MIE_BIT) & 1ULL) == 1ULL); + assert(((mstatus_after_mret >> MSTATUS_MPIE_BIT) & 1ULL) == 1ULL); + assert(((mstatus_after_mret >> MSTATUS_MPP_LO) & 0x3ULL) == PRIV_ENCODE_U); + std::cout << "[PASS] mret restores interrupt enable bits" << std::endl; + + // sret restore flow + uint64_t sstatus_cfg = (1ULL << SSTATUS_SIE_BIT) | (1ULL << SSTATUS_SPP_BIT); + csr_op(dut, CSR_SSTATUS, CSR_OP_WRITE, sstatus_cfg); + dut->trap_is_sret = 1; + tick(dut); + dut->trap_is_sret = 0; + const uint64_t sstatus_after_sret = read_csr(dut, CSR_SSTATUS); + assert(((sstatus_after_sret >> SSTATUS_SIE_BIT) & 1ULL) == 0ULL); + assert(((sstatus_after_sret >> SSTATUS_SPIE_BIT) & 1ULL) == 1ULL); + assert(((sstatus_after_sret >> SSTATUS_SPP_BIT) & 1ULL) == 0ULL); + std::cout << "[PASS] sret updates supervisor status bits" << std::endl; + + // Ecall causes depend on current privilege mode + force_priv_mode_via_mret(dut, PRIV_ENCODE_S); + dut->trap_is_ecall = 1; + dut->trap_epc = 0x600ULL; + tick(dut); + dut->trap_is_ecall = 0; + dut->trap_epc = 0; + assert(read_csr(dut, CSR_MCAUSE) == EXC_ECALL_FROM_S); + assert(read_csr(dut, CSR_MTVAL) == 0ULL); + assert(read_csr(dut, CSR_MEPC) == 0x600ULL); + assert(((read_csr(dut, CSR_MSTATUS) >> MSTATUS_MPP_LO) & 0x3ULL) == PRIV_ENCODE_S); + + force_priv_mode_via_mret(dut, PRIV_ENCODE_U); + dut->trap_is_ecall = 1; + dut->trap_epc = 0x700ULL; + tick(dut); + dut->trap_is_ecall = 0; + dut->trap_epc = 0; + assert(read_csr(dut, CSR_MCAUSE) == EXC_ECALL_FROM_U); + assert(read_csr(dut, CSR_MTVAL) == 0ULL); + assert(read_csr(dut, CSR_MEPC) == 0x700ULL); + assert(((read_csr(dut, CSR_MSTATUS) >> MSTATUS_MPP_LO) & 0x3ULL) == PRIV_ENCODE_U); + std::cout << "[PASS] Ecall encodes mcause per privilege" << std::endl; + + // Trap delegation from U to S via medeleg + csr_op(dut, CSR_MEDELEG, CSR_OP_WRITE, 0ULL); + csr_op(dut, CSR_MEDELEG, CSR_OP_SET, (1ULL << EXC_ECALL_FROM_U)); + csr_op(dut, CSR_STVEC, CSR_OP_WRITE, 0x4000ULL); + force_priv_mode_via_mret(dut, PRIV_ENCODE_U); + dut->trap_is_ecall = 1; + dut->trap_epc = 0x900ULL; + tick(dut); + dut->trap_is_ecall = 0; + dut->trap_epc = 0; + assert(read_csr(dut, CSR_SEPC) == 0x900ULL); + assert(read_csr(dut, CSR_SCAUSE) == EXC_ECALL_FROM_U); + assert(read_csr(dut, CSR_STVAL) == 0ULL); + assert(dut->csr_priv_mode == PRIV_ENCODE_S); + assert(dut->csr_trap_to_s_mode); + assert(dut->csr_trap_vector == 0x4000ULL); + std::cout << "[PASS] medeleg routes ecall to supervisor" << std::endl; + force_priv_mode_via_mret(dut, PRIV_ENCODE_M); + + // Basic supervisor CSRs touching for completeness + csr_op(dut, CSR_SIE, CSR_OP_WRITE, 0x55ULL); + csr_op(dut, CSR_SSCRATCH, CSR_OP_WRITE, 0xAAULL); + csr_op(dut, CSR_SEPC, CSR_OP_WRITE, 0x1234ULL); + csr_op(dut, CSR_SCAUSE, CSR_OP_WRITE, 0x21ULL); + csr_op(dut, CSR_SIP, CSR_OP_WRITE, 0x3ULL); + csr_op(dut, CSR_SATP, CSR_OP_WRITE, 0x8000000000000000ULL); + assert(read_csr(dut, CSR_SIE) == 0x55ULL); + assert(read_csr(dut, CSR_SSCRATCH) == 0xAAULL); + assert(read_csr(dut, CSR_SEPC) == 0x1234ULL); + assert(read_csr(dut, CSR_SCAUSE) == 0x21ULL); + assert(read_csr(dut, CSR_SIP) == 0x3ULL); + assert(read_csr(dut, CSR_SATP) == 0x8000000000000000ULL); + std::cout << "[PASS] Supervisor space CSR read/write" << std::endl; + + // Writing SSTATUS should mirror MSTATUS subset bits + csr_op(dut, CSR_SSTATUS, CSR_OP_WRITE, (1ULL << SSTATUS_SIE_BIT)); + assert(((read_csr(dut, CSR_MSTATUS) >> SSTATUS_SIE_BIT) & 1ULL) == 1ULL); + csr_op(dut, CSR_SSTATUS, CSR_OP_WRITE, 0ULL); + assert(((read_csr(dut, CSR_MSTATUS) >> SSTATUS_SIE_BIT) & 1ULL) == 0ULL); + std::cout << "[PASS] SSTATUS write mirrors MSTATUS" << std::endl; + + // Floating-point CSR block + csr_op(dut, CSR_FFLAGS, CSR_OP_WRITE, 0x1FULL); + assert((read_csr(dut, CSR_FFLAGS) & 0x1FULL) == 0x1FULL); + csr_op(dut, CSR_FRM, CSR_OP_WRITE, 0x7ULL); + assert((read_csr(dut, CSR_FRM) & 0x7ULL) == 0x7ULL); + csr_op(dut, CSR_FCSR, CSR_OP_WRITE, 0xABULL); + assert((read_csr(dut, CSR_FFLAGS) & 0x1FULL) == (0xABULL & 0x1FULL)); + assert((read_csr(dut, CSR_FRM) & 0x7ULL) == ((0xABULL >> 5) & 0x7ULL)); + std::cout << "[PASS] FCSR/FM/FFLAGS read/write" << std::endl; + + std::cout << "----------------------------------\n"; + std::cout << "All CSR unit tests passed!\n"; + std::cout << "----------------------------------\n"; + + delete dut; + return 0; +} |