Use simulated UART in core test bench

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Makefile

@@ -12,7 +12,7 @@ all: $(all)
 	$(GHDL) -a $(GHDLFLAGS) $<
 
 common.o: decode_types.o
-core_tb.o: common.o wishbone_types.o core.o simple_ram_behavioural.o
+core_tb.o: common.o wishbone_types.o core.o simple_ram_behavioural.o sim_uart.o
 core.o: common.o wishbone_types.o fetch1.o fetch2.o decode1.o decode2.o register_file.o cr_file.o execute1.o execute2.o loadstore1.o loadstore2.o multiply.o writeback.o wishbone_arbiter.o
 cr_file.o: common.o
 crhelpers.o: common.o
@@ -34,6 +34,7 @@ multiply.o: common.o decode_types.o ppc_fx_insns.o crhelpers.o
 ppc_fx_insns.o: helpers.o
 register_file.o: common.o
 sim_console.o:
+sim_uart.o: sim_console.o
 simple_ram_behavioural_helpers.o:
 simple_ram_behavioural_tb.o: wishbone_types.o simple_ram_behavioural.o
 simple_ram_behavioural.o: wishbone_types.o simple_ram_behavioural_helpers.o

core_tb.vhdl

@@ -1,5 +1,7 @@
 library ieee;
 use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+use std.textio.all;
 
 library work;
 use work.common.all;
@@ -11,8 +13,14 @@ end core_tb;
 architecture behave of core_tb is
 	signal clk, rst: std_logic;
 
-	signal wishbone_in : wishbone_slave_out;
-	signal wishbone_out : wishbone_master_out;
+	signal wishbone_core_in : wishbone_slave_out;
+	signal wishbone_core_out : wishbone_master_out;
+
+	signal wishbone_ram_in : wishbone_slave_out;
+	signal wishbone_ram_out : wishbone_master_out;
+
+	signal wishbone_uart_in : wishbone_slave_out;
+	signal wishbone_uart_out : wishbone_master_out;
 
 	signal registers : regfile;
 	signal terminate : std_ulogic;
@@ -22,12 +30,55 @@ architecture behave of core_tb is
 begin
 	core_0: entity work.core
 		generic map (SIM => true)
-		port map (clk => clk, rst => rst, wishbone_in => wishbone_in,
-			  wishbone_out => wishbone_out, registers => registers, terminate_out => terminate);
+		port map (clk => clk, rst => rst, wishbone_in => wishbone_core_in,
+			  wishbone_out => wishbone_core_out, registers => registers, terminate_out => terminate);
 
 	simple_ram_0: entity work.simple_ram_behavioural
 		generic map ( filename => "simple_ram_behavioural.bin", size => 524288)
-		port map (clk => clk, rst => rst, wishbone_in => wishbone_out, wishbone_out => wishbone_in);
+		port map (clk => clk, rst => rst, wishbone_in => wishbone_ram_out, wishbone_out => wishbone_ram_in);
+
+	simple_uart_0: entity work.sim_uart
+		port map ( clk => clk, reset => rst, wishbone_in => wishbone_uart_out, wishbone_out => wishbone_uart_in);
+
+
+	bus_process: process(wishbone_core_out, wishbone_ram_in, wishbone_uart_in)
+	  -- Selected slave
+	  type slave_type is (SLAVE_UART, SLAVE_MEMORY, SLAVE_NONE);
+	  variable slave : slave_type;
+	begin
+		-- Simple address decoder
+		slave := SLAVE_NONE;
+		if wishbone_core_out.adr(31 downto 24) = x"00" then
+			slave := SLAVE_MEMORY;
+		elsif wishbone_core_out.adr(31 downto 24) = x"c0" then
+			if wishbone_core_out.adr(15 downto 12) = x"2" then
+				slave := SLAVE_UART;
+			end if;
+		end if;
+
+		-- Wishbone muxing:
+		-- Start with all master signals to all slaves, then override
+		-- cyc and stb accordingly
+		wishbone_ram_out <= wishbone_core_out;
+		wishbone_uart_out <= wishbone_core_out;
+		if slave = SLAVE_MEMORY then
+			wishbone_core_in <= wishbone_ram_in;
+		else
+			wishbone_ram_out.cyc <= '0';
+			wishbone_ram_out.stb <= '0';
+		end if;
+		if slave = SLAVE_UART then
+			wishbone_core_in <= wishbone_uart_in;
+		else
+			wishbone_uart_out.cyc <= '0';
+			wishbone_uart_out.stb <= '0';
+		end if;
+		if slave = SLAVE_NONE then
+			wishbone_core_in.dat <= (others => '1');
+			wishbone_core_in.ack <= wishbone_core_out.cyc and
+						wishbone_core_out.stb;
+		end if;
+	end process;
 
 	clk_process: process
 	begin