fw irq improvements (force high state for one clock when de-asserting irq)

fw/rtl/n64/n64_cfg.sv

@@ -138,7 +138,12 @@ module n64_cfg (
                             lock_sequence_counter <= 1'd0;
                         end
                         if (lock_sequence_counter == 1'd1) begin
-                            n64_scb.cfg_unlock <= (reg_bus.wdata != 16'hFFFF);
+                            if (reg_bus.wdata == 16'hFFFF) begin
+                                n64_scb.cfg_unlock <= 1'b0;
+                                cmd_irq_request <= 1'b0;
+                                cmd_irq <= 1'b0;
+                                mcu_irq <= 1'b0;
+                            end
                         end
                     end
 

fw/rtl/n64/n64_top.sv

@@ -26,13 +26,19 @@ module n64_top (
 
     logic n64_dd_irq;
     logic n64_cfg_irq;
-    logic n64_irq_oe;
+
+    logic irq_data;
+    logic irq_dq;
+    logic [1:0] irq_oe;
+
+    assign irq_data = (n64_dd_irq || n64_cfg_irq);
 
     always @(posedge clk) begin
-        n64_irq_oe <= (n64_dd_irq || n64_cfg_irq);
+        irq_dq <= (~irq_data);
+        irq_oe <= {irq_oe[0], irq_data};
     end
 
-    assign n64_irq = n64_irq_oe ? 1'b0 : 1'bZ;
+    assign n64_irq = irq_oe[1] ? irq_dq : 1'bZ;
 
     n64_reg_bus reg_bus ();