ecp5: Sim model fixes

Signed-off-by: David Shah <dave@ds0.me>

techlibs/ecp5/cells_sim.v

@@ -265,16 +265,18 @@ module TRELLIS_IO(
 	output O
 );
 	parameter DIR = "INPUT";
+	reg T_pd;
+	always @(*) if (T === 1'bz) T_pd <= 1'b0; else T_pd <= T;
 
 	generate
 		if (DIR == "INPUT") begin
 			assign B = 1'bz;
 			assign O = B;
 		end else if (DIR == "OUTPUT") begin
-			assign B = T ? 1'bz : I;
+			assign B = T_pd ? 1'bz : I;
 			assign O = 1'bx;
-		end else if (DIR == "INOUT") begin
-			assign B = T ? 1'bz : I;
+		end else if (DIR == "BIDIR") begin
+			assign B = T_pd ? 1'bz : I;
 			assign O = B;
 		end else begin
 			ERROR_UNKNOWN_IO_MODE error();