antonblanchard.microwatt/dmi_dtm_tb.vhdl

library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;

library work;
use work.common.all;
use work.wishbone_types.all;

library unisim;
use unisim.vcomponents.all;

entity dmi_dtm_tb is
end dmi_dtm_tb;

architecture behave of dmi_dtm_tb is
    signal clk           : std_ulogic;
    signal rst           : std_ulogic;
    constant clk_period  : time := 10 ns;
    constant jclk_period : time := 30 ns;

    -- DMI debug bus signals
    signal dmi_addr	: std_ulogic_vector(7 downto 0);
    signal dmi_din	: std_ulogic_vector(63 downto 0);
    signal dmi_dout	: std_ulogic_vector(63 downto 0);
    signal dmi_req	: std_ulogic;
    signal dmi_wr	: std_ulogic;
    signal dmi_ack	: std_ulogic;

    -- Global JTAG signals (used by BSCANE2 inside dmi_dtm
    alias j : glob_jtag_t is glob_jtag;

    -- Wishbone interfaces
    signal wishbone_ram_in : wishbone_slave_out;
    signal wishbone_ram_out : wishbone_master_out;

begin
    dtm: entity work.dmi_dtm
	generic map(
	    ABITS => 8,
	    DBITS => 64
	    )
	port map(
	    sys_clk	=> clk,
	    sys_reset	=> rst,
	    dmi_addr	=> dmi_addr,
	    dmi_din	=> dmi_din,
	    dmi_dout	=> dmi_dout,
	    dmi_req	=> dmi_req,
	    dmi_wr	=> dmi_wr,
	    dmi_ack	=> dmi_ack
	    );

    -- Dummy loopback until a debug module is present
    dmi_din <= dmi_dout;
    dmi_ack <= dmi_ack;

    -- system clock
    sys_clk: process
    begin
	clk <= '1';
	wait for clk_period / 2;
	clk <= '0';
	wait for clk_period / 2;
    end process sys_clk;

    -- system sim: just reset and wait
    sys_sim: process
    begin
	rst <= '1';
	wait for clk_period;
	rst <= '0';
	wait;
    end process;

    -- jtag sim process
    sim_jtag: process
	procedure clock(count: in INTEGER) is
	begin
	    for i in 1 to count loop
		j.tck <= '0';
		wait for jclk_period/2;
		j.tck <= '1';
		wait for jclk_period/2;
	    end loop;
	end procedure clock;

	procedure shift_out(val: in std_ulogic_vector) is
	begin
	    for i in 0 to val'length-1 loop
		j.tdi <= val(i);
		clock(1);
	    end loop;
	end procedure shift_out;

	procedure shift_in(val: out std_ulogic_vector) is
	begin
	    for i in val'length-1 downto 0 loop
		val := j.tdo & val(val'length-1 downto 1);
		clock(1);
	    end loop;
	end procedure shift_in;

	procedure send_command(
	    addr : in std_ulogic_vector(7 downto 0);
	    data : in std_ulogic_vector(63 downto 0);
	    op   : in std_ulogic_vector(1 downto 0)) is
	begin
	    j.capture <= '1';
	    clock(1);
	    j.capture <= '0';	
	    clock(1);
	    j.shift <= '1';
	    shift_out(op);
	    shift_out(data);
	    shift_out(addr);
	    j.shift <= '0';
	    j.update <= '1';
	    clock(1);
	    j.update <= '0';
	    clock(1);
	end procedure send_command;	

	procedure read_resp(
	    op   : out std_ulogic_vector(1 downto 0);
	    data : out std_ulogic_vector(63 downto 0)) is

	    variable addr : std_ulogic_vector(7 downto 0);
	begin
	    j.capture <= '1';
	    clock(1);
	    j.capture <= '0';	
	    clock(1);
	    j.shift <= '1';
	    shift_in(op);
	    shift_in(data);
	    shift_in(addr);
	    j.shift <= '0';
	    j.update <= '1';
	    clock(1);
	    j.update <= '0';
	    clock(1);
	end procedure read_resp;	

	procedure dmi_write(addr : in std_ulogic_vector(7 downto 0);
			    data : in std_ulogic_vector(63 downto 0)) is
	    variable resp_op   : std_ulogic_vector(1 downto 0);
	    variable resp_data : std_ulogic_vector(63 downto 0);
	    variable timeout   : integer;
	begin
	    send_command(addr, data, "10");
	    loop
		read_resp(resp_op, resp_data);
		case resp_op is
		when "00" =>
		    return;
		when "11" =>
		    timeout := timeout + 1;
		    assert timeout < 0
			report "dmi_write timed out !" severity error;
		when others =>
		    assert 0 > 1 report "dmi_write got odd status: " &
			to_hstring(resp_op) severity error;
		end case;
	    end loop;
	end procedure dmi_write;
	

	procedure dmi_read(addr : in std_ulogic_vector(7 downto 0);
			   data : out std_ulogic_vector(63 downto 0)) is
	    variable resp_op   : std_ulogic_vector(1 downto 0);
	    variable timeout   : integer;
	begin
	    send_command(addr, (others => '0'), "01");
	    loop
		read_resp(resp_op, data);
		case resp_op is
		when "00" =>
		    return;
		when "11" =>
		    timeout := timeout + 1;
		    assert timeout < 0
			report "dmi_read timed out !" severity error;
		when others =>
		    assert 0 > 1 report "dmi_read got odd status: " &
			to_hstring(resp_op) severity error;
		end case;
	    end loop;
	end procedure dmi_read;

	variable data : std_ulogic_vector(63 downto 0);
    begin
	-- init & reset
	j.reset <= '1';
	j.sel <= "0000";
	j.capture <= '0';
	j.update <= '0';
	j.shift <= '0';
	j.tdi <= '0';
	j.tms <= '0';
	j.runtest <= '0';
	clock(5);
	j.reset <= '0';
	clock(5);

	-- select chain 2
	j.sel <= "0010";
	clock(1);

	-- send command
	dmi_read(x"00", data);
	report "Read addr reg:" & to_hstring(data);
	std.env.finish;
    end process;
end behave;