Intital revision

git-svn-id: http://moon:8086/svn/vhdl/trunk@19 cc03376c-175c-47c8-b038-4cd826a8556b

lib/misc/async_port.vhd

@@ -0,0 +1,242 @@
+-----------------------------------------------------------------------
+-- $Header: /tmp/cvsroot/VHDL/lib/misc/async_port.vhd,v 1.1 2008-09-21 08:25:59 Jens Exp $
+-----------------------------------------------------------------------
+library IEEE;
+use IEEE.STD_LOGIC_1164.ALL;
+use IEEE.NUMERIC_STD.ALL;
+use work.sys_types.all;
+
+	------------------------------------------------------------------
+entity async_port is
+	Generic
+	(
+		addr_width		: natural := 32;
+		data_width		: natural := 32;
+		async_timespec	: async_timespec_t
+	);
+	Port
+	(
+		rst			: in std_logic;
+		clk			: in std_logic;
+		cpu_en		: in std_logic;
+		cpu_re		: in std_logic;
+		cpu_addr	: in unsigned(addr_width-1 downto 0);
+		cpu_din		: out unsigned(data_width-1 downto 0);
+		cpu_dout	: in unsigned(data_width-1 downto 0);
+		cpu_bsy		: out std_logic;
+		cpu_vld		: out std_logic;
+		async_a		: out unsigned(addr_width-1 downto 0);
+		async_d		: inout unsigned(data_width-1 downto 0);
+		async_cs	: out std_logic;
+		async_wr	: out std_logic;
+		async_rd	: out std_logic;
+		async_rst	: out std_logic
+	);
+end async_port;
+
+architecture Behavioral of async_port is
+
+	type async_t is record
+		cs		: std_logic;
+		wr		: std_logic;
+		rd		: std_logic;
+		rst		: std_logic;
+		drive_d	: std_logic;
+	end record;
+	
+	type async_state_t is (start, reset, rdy, leadin_rd, read, leadin_wr, write, leadout_rd, leadout_wr, release);
+	
+	signal s, sn : async_state_t;
+	signal as : async_t;
+	signal cc_rst : std_logic;
+	signal cycle_cnt	: natural range 0 to 15;
+	signal cycle_reload	: natural range 0 to 15;
+
+	------------------------------------------------------------------
+	begin
+
+	proc_cycle_counter:
+	process(clk)
+	begin
+		if rising_edge(clk) then
+			if cc_rst = '1' then
+				cycle_cnt <= cycle_reload;
+			elsif cycle_cnt /= 0 then
+				cycle_cnt <= cycle_cnt - 1;
+			end if;
+		end if;
+	end process;
+	
+	------------------------------------------------------------------
+	proc_state_next:
+	process(clk)
+	begin
+		if rising_edge(clk) then
+			if rst = '1' then
+				s <= start;
+			else
+				s <= sn;
+			end if;
+		end if;
+	end process;
+	
+	proc_state:
+	process(s, cycle_cnt, cpu_en)
+	begin
+		
+		cycle_reload	<= async_timespec.ncyc_pulse_rst;
+		cc_rst			<= '0';
+		as.rst			<= '0';
+		as.cs			<= '0';
+		as.wr			<= '0';
+		as.rd			<= '0';
+		as.drive_d		<= '0';
+		cpu_bsy			<= '1';
+		cpu_vld			<= '0';
+		
+		sn	<= s;
+		case s is
+		
+		when start =>
+			cc_rst	<= '1';
+			sn		<= reset;
+		when reset =>
+			as.rst	<= '1';
+			if cycle_cnt = 0 then
+				sn	<= rdy;
+			end if;
+		when rdy =>
+			cpu_bsy		<= '0';
+			if cpu_en = '1' then
+				as.cs			<= '1';
+				cc_rst			<= '1';
+				cycle_reload	<= async_timespec.ncyc_access-1;
+				if cpu_re = '1' then
+					sn				<= leadin_rd;
+				else
+					sn				<= leadin_wr;
+				end if;
+			end if;
+
+		when leadin_rd =>
+			as.cs		<= '1';
+			if cycle_cnt = 0 then
+				cc_rst			<= '1';
+				cycle_reload	<= async_timespec.ncyc_pulse_rd-1;
+				as.rd			<= '1';
+				sn				<= read;
+			end if;
+
+		when leadin_wr =>
+			as.cs		<= '1';
+			if cycle_cnt = 0 then
+				cc_rst			<= '1';
+				cycle_reload	<= async_timespec.ncyc_pulse_wr-1;
+				as.wr			<= '1';
+				as.drive_d		<= '1';
+				sn				<= write;
+			end if;
+	
+		when read =>
+			as.cs		<= '1';
+			as.rd		<= '1';
+			if cycle_cnt = 0 then
+				cpu_vld	<= '1';
+				cc_rst			<= '1';
+				cycle_reload	<= async_timespec.ncyc_cs_hold-1;
+				as.rd			<= '0';
+				sn				<= leadout_rd;
+			end if;
+				
+		when write =>
+			as.drive_d	<= '1';
+			as.cs		<= '1';
+			as.wr		<= '1';
+			if cycle_cnt = 0 then
+				as.wr			<= '0';
+				cc_rst			<= '1';
+				cycle_reload	<= async_timespec.ncyc_cs_hold-1;
+				sn				<= leadout_wr;
+			end if;
+
+		when leadout_rd =>
+			as.cs		<= '1';
+			if cycle_cnt = 0 then
+				cc_rst			<= '1';
+				cycle_reload	<= async_timespec.ncyc_release-1;
+				sn				<= release;
+				as.cs			<= '0';
+			end if;
+
+		when leadout_wr =>
+			as.cs		<= '1';
+			as.drive_d	<= '1';
+			if cycle_cnt = 0 then
+				cc_rst			<= '1';
+				cycle_reload	<= async_timespec.ncyc_release-1;
+				sn				<= release;
+				as.cs			<= '0';
+			end if;
+
+		when release =>
+			if cycle_cnt = 0 then
+				sn				<= rdy;
+			end if;
+
+		when others =>
+			sn <= rdy;
+			
+		end case;		
+	end process;
+
+	------------------------------------------------------------------
+	output_ctrl:
+	process(clk)
+	begin
+		if rising_edge(clk) then
+			async_cs	<= (not async_timespec.pol_cs) xor as.cs;
+			async_wr	<= (not async_timespec.pol_we) xor as.wr;
+			async_rd	<= (not async_timespec.pol_oe) xor as.rd;
+			async_rst	<= (not async_timespec.pol_rst) xor as.rst;
+		end if;
+	end process;
+
+	------------------------------------------------------------------
+	din_register:
+	process(clk)
+	begin
+		if rising_edge(clk) then
+			if as.rd = '1' then
+				cpu_din 	<= async_d;
+			end if;	
+		end if;
+	end process;
+
+	------------------------------------------------------------------
+	output_addr:
+	process(clk)
+	begin
+		if rising_edge(clk) then
+			if rst = '1' then
+				async_a 	<= (others => '0');
+			elsif cpu_en = '1' then
+				async_a 	<= cpu_addr;
+			end if;	
+		end if;
+	end process;
+
+	------------------------------------------------------------------
+	output_data:
+	process(clk)
+	begin
+		if rising_edge(clk) then
+			async_d 	<= (others => 'Z');
+			if as.drive_d = '1' then
+				async_d 	<= cpu_dout;
+			end if;	
+		end if;
+	end process;
+
+	------------------------------------------------------------------
+
+end Behavioral;