Subversion Repositories udp_ip_stack

--------------------------------------------------------------------------------
-- Project    : low latency UDP
-- File       : xv6mac_straight
-- Version    : 0.0
-------------------------------------------------------------------------------
--
--
-- Description:  This is an adaptation of the Xilinx V6 MAC layer, but without the FIFOs
--
--
--
--    ---------------------------------------------------------------------
--    | EXAMPLE DESIGN WRAPPER                                            |
--    |           --------------------------------------------------------|
--    |           |FIFO BLOCK WRAPPER                                     |
--    |           |                                                       |
--    |           |                                                       |
--    |           |              -----------------------------------------|
--    |           |              | BLOCK LEVEL WRAPPER                    |
--    |           |              |    ---------------------               |
--    |           |              |    |   V6 EMAC CORE    |               |
--    |           |              |    |                   |               |
--    |           |              |    |                   |               |
--    |           |              |    |                   |               |
--    |           |              |    |                   |               |
--    |           |              |    |                   |               |
--    | |      |  |              |    |                   |  ---------    |
--    | |      |->|->----------->|--|--->| Tx            Tx  |--|       |--->|
--    | |      |  |              |    | AXI-S         PHY |  |       |    |
--    | |      |  |              |    | I/F           I/F |  |       |    |
--    | |      |  |              |    |                   |  | PHY   |    |
--    | |      |  |              |    |                   |  | I/F   |    |
--    | |      |  |              |    |                   |  |       |    |
--    | |      |  |              |    | Rx            Rx  |  |       |    |
--    | |      |  |              |    | AX)-S         PHY |  |       |    |
--    | |      |<-|<-------------|----| I/F           I/F |<-|       |<---|
--    | |      |  |              |    |                   |  ---------    |
--    | --------  |              |    ---------------------               |
--    |           |              |                                        |
--    |           |              -----------------------------------------|
--    |           --------------------------------------------------------|
--    ---------------------------------------------------------------------
--
--------------------------------------------------------------------------------
 
library unisim;
use unisim.vcomponents.all;
 
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
use ieee.numeric_std.all;
 
entity xv6mac_straight is
    port (
		-- System controls
		------------------
      glbl_rst                      : in  std_logic;	      				-- asynchronous reset
      mac_reset                   	: in  std_logic;							-- reset mac layer
      clk_in_p              			: in  std_logic;     	 				-- 200MHz clock input from board
      clk_in_n              			: in  std_logic;      
 
		-- MAC Transmitter (AXI-S) Interface
      ---------------------------------------------
      mac_tx_clock              		: out  std_logic;							-- data sampled on rising edge
      mac_tx_tdata         			: in  std_logic_vector(7 downto 0);	-- data byte to tx
      mac_tx_tvalid        			: in  std_logic;							-- tdata is valid
      mac_tx_tready        			: out std_logic;							-- mac is ready to accept data
      mac_tx_tlast         			: in  std_logic;							-- indicates last byte of frame
 
      -- MAC Receiver (AXI-S) Interface
      ------------------------------------------
      mac_rx_clock              		: out  std_logic;							-- data valid on rising edge
      mac_rx_tdata         			: out std_logic_vector(7 downto 0);	-- data byte received
      mac_rx_tvalid        			: out std_logic;							-- indicates tdata is valid
      mac_rx_tready        			: in  std_logic;							-- tells mac that we are ready to take data
      mac_rx_tlast         			: out std_logic;							-- indicates last byte of the trame
 
      -- GMII Interface
      -----------------     
      phy_resetn            			: out std_logic;
      gmii_txd                      : out std_logic_vector(7 downto 0);
      gmii_tx_en                    : out std_logic;
      gmii_tx_er                    : out std_logic;
      gmii_tx_clk                   : out std_logic;
      gmii_rxd                      : in  std_logic_vector(7 downto 0);
      gmii_rx_dv                    : in  std_logic;
      gmii_rx_er                    : in  std_logic;
      gmii_rx_clk                   : in  std_logic;
      gmii_col                      : in  std_logic;
      gmii_crs                      : in  std_logic;
      mii_tx_clk                    : in  std_logic
		);
end xv6mac_straight;
 
architecture wrapper of xv6mac_straight is
 
  ------------------------------------------------------------------------------
  -- Component declaration for the internal mac layer
  ------------------------------------------------------------------------------
  component mac_layer_v2_2_block
   port(
      gtx_clk                       : in std_logic;
 
      -- Receiver Interface
      ----------------------------
      rx_statistics_vector          : out std_logic_vector(27 downto 0);
      rx_statistics_valid           : out std_logic;
 
      rx_mac_aclk                   : out std_logic;
      rx_reset                      : out std_logic;
      rx_axis_mac_tdata             : out std_logic_vector(7 downto 0);
      rx_axis_mac_tvalid            : out std_logic;
      rx_axis_mac_tlast             : out std_logic;
      rx_axis_mac_tuser             : out std_logic;
 
      -- Transmitter Interface
      -------------------------------
      tx_ifg_delay                  : in std_logic_vector(7 downto 0);
      tx_statistics_vector          : out std_logic_vector(31 downto 0);
      tx_statistics_valid           : out std_logic;
 
      tx_reset                      : out std_logic;
      tx_axis_mac_tdata             : in std_logic_vector(7 downto 0);
      tx_axis_mac_tvalid            : in std_logic;
      tx_axis_mac_tlast             : in std_logic;
      tx_axis_mac_tuser             : in std_logic;
      tx_axis_mac_tready            : out std_logic;
      tx_collision                  : out std_logic;
      tx_retransmit                 : out std_logic;
 
      -- MAC Control Interface
      ------------------------
      pause_req                     : in std_logic;
      pause_val                     : in std_logic_vector(15 downto 0);
 
      -- Reference clock for IDELAYCTRL's
      refclk                        : in std_logic;
 
      -- GMII Interface
      -----------------
      gmii_txd                      : out std_logic_vector(7 downto 0);
      gmii_tx_en                    : out std_logic;
      gmii_tx_er                    : out std_logic;
      gmii_tx_clk                   : out std_logic;
      gmii_rxd                      : in std_logic_vector(7 downto 0);
      gmii_rx_dv                    : in std_logic;
      gmii_rx_er                    : in std_logic;
      gmii_rx_clk                   : in std_logic;
 
      -- asynchronous reset
      -----------------
      glbl_rstn                     : in std_logic;
      rx_axi_rstn                   : in std_logic;
      tx_axi_rstn                   : in std_logic
 
      );
  end component;
 
 
  ------------------------------------------------------------------------------
  -- Component Declaration for the Clock generator
  ------------------------------------------------------------------------------
 
   component clk_wiz_v2_2
   port (
      -- Clock in ports
      CLK_IN1_P                 : in  std_logic;
      CLK_IN1_N                 : in  std_logic;
      -- Clock out ports
      CLK_OUT1                  : out std_logic;
      CLK_OUT2                  : out std_logic;
      CLK_OUT3                  : out std_logic;
      -- Status and control signals
      RESET                     : in  std_logic;
      LOCKED                    : out std_logic
   );
   end component;
 
 
  ------------------------------------------------------------------------------
  -- Component declaration for the reset synchroniser
  ------------------------------------------------------------------------------
  component reset_sync_v2_2
  port (
     reset_in                   : in  std_logic;    -- Active high asynchronous reset
     enable                     : in  std_logic;
     clk                        : in  std_logic;    -- clock to be sync'ed to
     reset_out                  : out std_logic     -- "Synchronised" reset signal
  );
  end component;
 
  ------------------------------------------------------------------------------
  -- Component declaration for the synchroniser
  ------------------------------------------------------------------------------
  component sync_block_v2_2
  port (
     clk                        : in  std_logic;
     data_in                    : in  std_logic;
     data_out                   : out std_logic
  );
  end component;
 
   ------------------------------------------------------------------------------
   -- Constants used in this top level wrapper.
   ------------------------------------------------------------------------------
   constant BOARD_PHY_ADDR                  : std_logic_vector(7 downto 0)  := "00000111";
 
 
   ------------------------------------------------------------------------------
   -- internal signals used in this top level wrapper.
   ------------------------------------------------------------------------------
 
   -- example design clocks
   signal gtx_clk_bufg                      : std_logic;
   signal refclk_bufg                       : std_logic;
   signal rx_mac_aclk                       : std_logic;
 
	-- tx handshaking
	signal mac_tx_tready_int						: std_logic;
	signal tx_full_reg								: std_logic;
	signal tx_full_val								: std_logic;
	signal tx_data_reg								: std_logic_vector(7 downto 0);
	signal tx_last_reg								: std_logic;
	signal set_tx_reg									: std_logic;
 
   signal phy_resetn_int                    : std_logic;
 
   -- resets (and reset generation)
   signal local_chk_reset                   : std_logic;
   signal chk_reset_int                     : std_logic;
   signal chk_pre_resetn                    : std_logic := '0';
   signal chk_resetn                        : std_logic := '0';
   signal dcm_locked                        : std_logic;
 
   signal glbl_rst_int                      : std_logic;
   signal phy_reset_count                   : unsigned(5 downto 0);
   signal glbl_rst_intn                     : std_logic;
 
	-- pipeline register for RX signals
	signal rx_data_val								: std_logic_vector(7 downto 0);
	signal rx_tvalid_val								: std_logic;
	signal rx_tlast_val								: std_logic;
	signal rx_data_reg								: std_logic_vector(7 downto 0);
	signal rx_tvalid_reg								: std_logic;
	signal rx_tlast_reg								: std_logic;
 
  attribute keep : string;
  attribute keep of gtx_clk_bufg             : signal is "true";
  attribute keep of refclk_bufg              : signal is "true";
  attribute keep of mac_tx_tready_int        : signal is "true";
  attribute keep of tx_full_reg        		: signal is "true";
 
 
  ------------------------------------------------------------------------------
  -- Begin architecture
  ------------------------------------------------------------------------------
 
begin
 
	combinatorial: process (
		rx_data_reg, rx_tvalid_reg, rx_tlast_reg,
		mac_tx_tvalid, mac_tx_tready_int, tx_full_reg, tx_full_val, set_tx_reg
		)
	begin
		-- output followers
      mac_rx_tdata  <= rx_data_reg;
      mac_rx_tvalid <= rx_tvalid_reg;
      mac_rx_tlast  <= rx_tlast_reg;
		mac_tx_tready <= not (tx_full_reg and not mac_tx_tready_int);		-- if not full, we are ready to accept
 
		-- control defaults
		tx_full_val <= tx_full_reg;
		set_tx_reg <= '0';
 
		-- tx handshaking logic
		if mac_tx_tvalid = '1' then
			tx_full_val <= '1';
			set_tx_reg <= '1';
		elsif mac_tx_tready_int = '1' then
			tx_full_val <= '0';
		end if;
 
	end process;
 
   sequential: process(gtx_clk_bufg)
   begin		
		if rising_edge(gtx_clk_bufg) then
			if chk_resetn = '0' then
				-- reset state variables
				rx_data_reg <= (others => '0');
				rx_tvalid_reg <= '0';
				rx_tlast_reg <= '0';
				tx_full_reg <= '0';
				tx_data_reg <= (others => '0');
				tx_last_reg <= '0';
			else
				-- register rx data
				rx_data_reg <= rx_data_val;
				rx_tvalid_reg <= rx_tvalid_val;
				rx_tlast_reg <= rx_tlast_val;
 
				-- process tx tvalid and tready
				tx_full_reg <= tx_full_val;
				if set_tx_reg = '1' then
					tx_data_reg <= mac_tx_tdata;
					tx_last_reg <= mac_tx_tlast;
				else
					tx_data_reg <= tx_data_reg;
					tx_last_reg <= tx_last_reg;
				end if;
			end if;
		end if;
	end process;
 
   ------------------------------------------------------------------------------
   -- Instantiate the Tri-Mode EMAC Block wrapper
   ------------------------------------------------------------------------------
   v6emac_block : mac_layer_v2_2_block
   port map(
      gtx_clk               => gtx_clk_bufg,
 
      -- Client Receiver Interface
      rx_statistics_vector  => open,
      rx_statistics_valid   => open,
 
      rx_mac_aclk           => open,
      rx_reset              => open,
      rx_axis_mac_tdata     => rx_data_val,
      rx_axis_mac_tvalid    => rx_tvalid_val,
      rx_axis_mac_tlast     => rx_tlast_val,
      rx_axis_mac_tuser     => open,
 
      -- Client Transmitter Interface
      tx_ifg_delay          => x"00",
      tx_statistics_vector  => open,
      tx_statistics_valid   => open,
 
      tx_reset              => open,
      tx_axis_mac_tdata     => tx_data_reg,
      tx_axis_mac_tvalid    => tx_full_reg,
      tx_axis_mac_tlast     => tx_last_reg,
      tx_axis_mac_tuser     => '0',
      tx_axis_mac_tready    => mac_tx_tready_int,
      tx_collision          => open,
      tx_retransmit         => open,
 
      -- Flow Control
      pause_req             => '0',
      pause_val             => x"0000",
 
      -- Reference clock for IDELAYCTRL's
      refclk                => refclk_bufg,
 
      -- GMII Interface
      gmii_txd              => gmii_txd,
      gmii_tx_en            => gmii_tx_en,
      gmii_tx_er            => gmii_tx_er,
      gmii_tx_clk           => gmii_tx_clk,
      gmii_rxd              => gmii_rxd,
      gmii_rx_dv            => gmii_rx_dv,
      gmii_rx_er            => gmii_rx_er,
      gmii_rx_clk           => gmii_rx_clk,
 
      -- asynchronous reset
      glbl_rstn             => chk_resetn,
      rx_axi_rstn           => '1',
      tx_axi_rstn           => '1'
   );
 
 
 
   ------------------------------------------------------------------------------
   -- Clock logic to generate required clocks from the 200MHz on board
   -- if 125MHz is available directly this can be removed
   ------------------------------------------------------------------------------
   clock_generator : clk_wiz_v2_2
   port map (
      -- Clock in ports
      CLK_IN1_P         => clk_in_p,
      CLK_IN1_N         => clk_in_n,
      -- Clock out ports
      CLK_OUT1          => gtx_clk_bufg,
      CLK_OUT2          => open,
      CLK_OUT3          => refclk_bufg,
      -- Status and control signals
      RESET             => glbl_rst,
      LOCKED            => dcm_locked
   );
 
   -----------------
   -- global reset
   glbl_reset_gen : reset_sync_v2_2
   port map (
      clk               => gtx_clk_bufg,
      enable            => dcm_locked,
      reset_in          => glbl_rst,
      reset_out         => glbl_rst_int
   );
 
   glbl_rst_intn <= not glbl_rst_int;
 
   -- generate the user side clocks
	mac_tx_clock <= gtx_clk_bufg;
	mac_rx_clock <= gtx_clk_bufg;
 
   ------------------------------------------------------------------------------
   -- Generate resets 
   ------------------------------------------------------------------------------
   -- in each case the async reset is first captured and then synchronised
 
 
  local_chk_reset <= glbl_rst or mac_reset;
 
  -----------------
  -- data check reset
   chk_reset_gen : reset_sync_v2_2
   port map (
       clk              => gtx_clk_bufg,
       enable           => dcm_locked,
       reset_in         => local_chk_reset,
       reset_out        => chk_reset_int
   );
 
   -- Create fully synchronous reset in the gtx clock domain.
   gen_chk_reset : process (gtx_clk_bufg)
   begin
     if gtx_clk_bufg'event and gtx_clk_bufg = '1' then
       if chk_reset_int = '1' then
         chk_pre_resetn   <= '0';
         chk_resetn       <= '0';
       else
         chk_pre_resetn   <= '1';
         chk_resetn       <= chk_pre_resetn;
       end if;
     end if;
   end process gen_chk_reset;
 
 
   -----------------
   -- PHY reset
   -- the phy reset output (active low) needs to be held for at least 10x25MHZ cycles
   -- this is derived using the 125MHz available and a 6 bit counter
   gen_phy_reset : process (gtx_clk_bufg)
   begin
     if gtx_clk_bufg'event and gtx_clk_bufg = '1' then
       if glbl_rst_intn = '0' then
         phy_resetn_int       <= '0';
         phy_reset_count      <= (others => '0');			
       else
          if phy_reset_count /= "111111" then
             phy_reset_count <= phy_reset_count + "000001";
          else
             phy_resetn_int   <= '1';
          end if;
       end if;
     end if;
   end process gen_phy_reset;
 
   phy_resetn <= phy_resetn_int;
 
 
end wrapper;