move nmi to irq 32 (#139)

* move nmi to irq 32

* fix exc cause

* update top tracing

* fix mcause read

rtl/cve2_controller.sv

@@ -303,7 +303,7 @@ module cve2_controller #(
   always_comb begin : gen_mfip_id
     mfip_id = 4'd0;
 
-    for (int i = 14; i >= 0; i--) begin
+    for (int i = 15; i >= 0; i--) begin
       if (irqs_i.irq_fast[i]) begin
         mfip_id = i[3:0];
       end
@@ -499,12 +499,13 @@ module cve2_controller #(
           if (irq_nm_i && !nmi_mode_q) begin
             exc_cause_o = EXC_CAUSE_IRQ_NM;
             nmi_mode_d  = 1'b1; // enter NMI mode
-          end else if (irqs_i.irq_fast != 15'b0) begin
+          end else if (irqs_i.irq_fast != 16'b0) begin
             // generate exception cause ID from fast interrupt ID:
             // - first bit distinguishes interrupts from exceptions,
-            // - second bit adds 16 to fast interrupt ID
-            // for example EXC_CAUSE_IRQ_FAST_0 = {1'b1, 5'd16}
-            exc_cause_o = exc_cause_e'({2'b11, mfip_id});
+            // - third bit adds 16 to fast interrupt ID so that the interrup 0 becomes 16 and the interrupt 15 becomes 31 (hence 5bits)
+            // - second bit is always 0 as the FAST interrupts are represented in the first 5bits, the 6th is always 0 cause is used by the NMI (in that case is 1 as represented by the number 32)
+            // for example EXC_CAUSE_IRQ_FAST_0 = {1'b1, 6'd16}
+            exc_cause_o = exc_cause_e'({3'b101, mfip_id});
           end else if (irqs_i.irq_external) begin
             exc_cause_o = EXC_CAUSE_IRQ_EXTERNAL_M;
           end else if (irqs_i.irq_software) begin

rtl/cve2_core.sv

@@ -58,7 +58,7 @@ module cve2_core import cve2_pkg::*; #(
   input  logic                         irq_software_i,
   input  logic                         irq_timer_i,
   input  logic                         irq_external_i,
-  input  logic [14:0]                  irq_fast_i,
+  input  logic [15:0]                  irq_fast_i,
   input  logic                         irq_nm_i,       // non-maskeable interrupt
   output logic                         irq_pending_o,
 

rtl/cve2_cs_registers.sv

@@ -53,7 +53,7 @@ module cve2_cs_registers #(
   input  logic                 irq_software_i,
   input  logic                 irq_timer_i,
   input  logic                 irq_external_i,
-  input  logic [14:0]          irq_fast_i,
+  input  logic [15:0]          irq_fast_i,
   input  logic                 nmi_mode_i,
   output logic                 irq_pending_o,          // interrupt request pending
   output cve2_pkg::irqs_t      irqs_o,                 // interrupt requests qualified with mie
@@ -169,7 +169,7 @@ module cve2_cs_registers #(
   logic        mscratch_en;
   logic [31:0] mepc_q, mepc_d;
   logic        mepc_en;
-  logic  [5:0] mcause_q, mcause_d;
+  logic  [6:0] mcause_q, mcause_d;
   logic        mcause_en;
   logic [31:0] mtval_q, mtval_d;
   logic        mtval_en;
@@ -189,7 +189,7 @@ module cve2_cs_registers #(
   status_stk_t mstack_q, mstack_d;
   logic        mstack_en;
   logic [31:0] mstack_epc_q, mstack_epc_d;
-  logic  [5:0] mstack_cause_q, mstack_cause_d;
+  logic  [6:0] mstack_cause_q, mstack_cause_d;
 
   // PMP Signals
   logic [31:0]                 pmp_addr_rdata  [PMP_MAX_REGIONS];
@@ -318,7 +318,7 @@ module cve2_cs_registers #(
       CSR_MEPC: csr_rdata_int = mepc_q;
 
       // mcause: exception cause
-      CSR_MCAUSE: csr_rdata_int = {mcause_q[5], 26'b0, mcause_q[4:0]};
+      CSR_MCAUSE: csr_rdata_int = {mcause_q[6], 25'b0, mcause_q[5:0]};
 
       // mtval: trap value
       CSR_MTVAL: csr_rdata_int = mtval_q;
@@ -482,7 +482,7 @@ module cve2_cs_registers #(
     mepc_en      = 1'b0;
     mepc_d       = {csr_wdata_int[31:1], 1'b0};
     mcause_en    = 1'b0;
-    mcause_d     = {csr_wdata_int[31], csr_wdata_int[4:0]};
+    mcause_d     = {csr_wdata_int[31], csr_wdata_int[5:0]};
     mtval_en     = 1'b0;
     mtval_d      = csr_wdata_int;
     mtvec_en     = csr_mtvec_init_i;
@@ -807,7 +807,7 @@ module cve2_cs_registers #(
 
   // MCAUSE
   cve2_csr #(
-    .Width     (6),
+    .Width     (7),
     .ShadowCopy(1'b0),
     .ResetValue('0)
   ) u_mcause_csr (
@@ -939,7 +939,7 @@ module cve2_cs_registers #(
 
   // MSTACK_CAUSE
   cve2_csr #(
-    .Width     (6),
+    .Width     (7),
     .ShadowCopy(1'b0),
     .ResetValue('0)
   ) u_mstack_cause_csr (

rtl/cve2_if_stage.sv

@@ -101,7 +101,7 @@ module cve2_if_stage import cve2_pkg::*; #(
 
   logic       [31:0] exc_pc;
 
-  logic        [5:0] irq_id;
+  logic        [6:0] irq_id;
   logic              unused_irq_bit;
 
   logic              if_id_pipe_reg_we; // IF-ID pipeline reg write enable
@@ -116,16 +116,16 @@ module cve2_if_stage import cve2_pkg::*; #(
 
   // extract interrupt ID from exception cause
   assign irq_id         = {exc_cause};
-  assign unused_irq_bit = irq_id[5];   // MSB distinguishes interrupts from exceptions
+  assign unused_irq_bit = irq_id[6];   // MSB distinguishes interrupts from exceptions
 
   // exception PC selection mux
   always_comb begin : exc_pc_mux
     unique case (exc_pc_mux_i)
-      EXC_PC_EXC:     exc_pc = { csr_mtvec_i[31:8], 8'h00                    };
-      EXC_PC_IRQ:     exc_pc = { csr_mtvec_i[31:8], 1'b0, irq_id[4:0], 2'b00 };
+      EXC_PC_EXC:     exc_pc = { csr_mtvec_i[31:8], 8'h00              };
+      EXC_PC_IRQ:     exc_pc = { csr_mtvec_i[31:8], irq_id[5:0], 2'b00 };
       EXC_PC_DBD:     exc_pc = DmHaltAddr;
       EXC_PC_DBG_EXC: exc_pc = DmExceptionAddr;
-      default:        exc_pc = { csr_mtvec_i[31:8], 8'h00                    };
+      default:        exc_pc = { csr_mtvec_i[31:8], 8'h00              };
     endcase
   end
 

rtl/cve2_pkg.sv

@@ -292,26 +292,25 @@ package cve2_pkg;
     logic        irq_software;
     logic        irq_timer;
     logic        irq_external;
-    logic [14:0] irq_fast; // 15 fast interrupts,
-                          // one interrupt is reserved for NMI (not visible through mip/mie)
+    logic [15:0] irq_fast; // 16 fast interrupts
   } irqs_t;
 
   // Exception cause
-  typedef enum logic [5:0] {
-    EXC_CAUSE_IRQ_SOFTWARE_M     = {1'b1, 5'd03},
-    EXC_CAUSE_IRQ_TIMER_M        = {1'b1, 5'd07},
-    EXC_CAUSE_IRQ_EXTERNAL_M     = {1'b1, 5'd11},
-    // EXC_CAUSE_IRQ_FAST_0      = {1'b1, 5'd16},
-    // EXC_CAUSE_IRQ_FAST_14     = {1'b1, 5'd30},
-    EXC_CAUSE_IRQ_NM             = {1'b1, 5'd31}, // == EXC_CAUSE_IRQ_FAST_15
-    EXC_CAUSE_INSN_ADDR_MISA     = {1'b0, 5'd00},
-    EXC_CAUSE_INSTR_ACCESS_FAULT = {1'b0, 5'd01},
-    EXC_CAUSE_ILLEGAL_INSN       = {1'b0, 5'd02},
-    EXC_CAUSE_BREAKPOINT         = {1'b0, 5'd03},
-    EXC_CAUSE_LOAD_ACCESS_FAULT  = {1'b0, 5'd05},
-    EXC_CAUSE_STORE_ACCESS_FAULT = {1'b0, 5'd07},
-    EXC_CAUSE_ECALL_UMODE        = {1'b0, 5'd08},
-    EXC_CAUSE_ECALL_MMODE        = {1'b0, 5'd11}
+  typedef enum logic [6:0] {
+    EXC_CAUSE_IRQ_SOFTWARE_M     = {1'b1, 6'd03},
+    EXC_CAUSE_IRQ_TIMER_M        = {1'b1, 6'd07},
+    EXC_CAUSE_IRQ_EXTERNAL_M     = {1'b1, 6'd11},
+    // EXC_CAUSE_IRQ_FAST_0      = {1'b1, 6'd16},
+    // EXC_CAUSE_IRQ_FAST_15     = {1'b1, 6'd31},
+    EXC_CAUSE_IRQ_NM             = {1'b1, 6'd32},
+    EXC_CAUSE_INSN_ADDR_MISA     = {1'b0, 6'd00},
+    EXC_CAUSE_INSTR_ACCESS_FAULT = {1'b0, 6'd01},
+    EXC_CAUSE_ILLEGAL_INSN       = {1'b0, 6'd02},
+    EXC_CAUSE_BREAKPOINT         = {1'b0, 6'd03},
+    EXC_CAUSE_LOAD_ACCESS_FAULT  = {1'b0, 6'd05},
+    EXC_CAUSE_STORE_ACCESS_FAULT = {1'b0, 6'd07},
+    EXC_CAUSE_ECALL_UMODE        = {1'b0, 6'd08},
+    EXC_CAUSE_ECALL_MMODE        = {1'b0, 6'd11}
   } exc_cause_e;
 
   // Debug cause
@@ -547,7 +546,7 @@ package cve2_pkg;
   parameter int unsigned CSR_MTIX_BIT      = 7;
   parameter int unsigned CSR_MEIX_BIT      = 11;
   parameter int unsigned CSR_MFIX_BIT_LOW  = 16;
-  parameter int unsigned CSR_MFIX_BIT_HIGH = 30;
+  parameter int unsigned CSR_MFIX_BIT_HIGH = 31;
 
   // CSR Machine Security Configuration bits
   parameter int unsigned CSR_MSECCFG_MML_BIT  = 0;

rtl/cve2_top.sv

@@ -53,7 +53,7 @@ module cve2_top import cve2_pkg::*; #(
   input  logic                         irq_software_i,
   input  logic                         irq_timer_i,
   input  logic                         irq_external_i,
-  input  logic [14:0]                  irq_fast_i,
+  input  logic [15:0]                  irq_fast_i,
   input  logic                         irq_nm_i,       // non-maskeable interrupt
 
   // Debug Interface

rtl/cve2_top_tracing.sv

@@ -49,7 +49,7 @@ module cve2_top_tracing import cve2_pkg::*; #(
   input  logic                         irq_software_i,
   input  logic                         irq_timer_i,
   input  logic                         irq_external_i,
-  input  logic [14:0]                  irq_fast_i,
+  input  logic [15:0]                  irq_fast_i,
   input  logic                         irq_nm_i,       // non-maskeable interrupt
 
   // Debug Interface