trashernet-soc/fpga/hdl/design/trashernet_phy_wb.vhd

-- -------------------------------------------------------------------------- --
--              TRASHERNET SoC - A Trashy Ethernet SoC for FPGAs              --
-- -------------------------------------------------------------------------- --
-- TODO
-- -------------------------------------------------------------------------- --
-- Author       : Markus Koch <markus@notsyncing.net>
-- Contributors : None
-- License      : Mozilla Public License (MPL) Version 2
-- -------------------------------------------------------------------------- --

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

library trashernet;
use trashernet.trashernet_pkg.all;

library generics;
use generics.all;
use generics.wishbone_pkg.all;

entity trashernet_phy_wb is
	generic(
		F_CLK     : in integer;         -- Clock frequency in Hz
		F_CLK_PHY : in integer
	);
	port(
		-- Global
		clk     : in  std_logic;        -- Global clock
		phy_clk : in  std_logic;        -- PHY clock
		rst     : in  std_logic;        -- Asynchronous reset

		-- Wishbone IF
		wb_o    : out wishbone_slave_out; -- Wishbone bus (out)
		wb_i    : in  wishbone_slave_in; -- Wishbone bus (in)

		-- Ethernet physical signals
		rx_p    : in  std_logic;
		tx_p    : out std_logic;
		tx_n    : out std_logic
	);
end entity trashernet_phy_wb;

architecture RTL of trashernet_phy_wb is
	-- PHY application interface
	signal phy_out : phy_out_t;         -- PHY application IF (out)
	signal phy_in  : phy_in_t;          -- PHY application IF (in)

	signal wb_adr : unsigned(2 downto 2);

	signal status_register : std_logic_vector(31 downto 0);

	signal rx_fifo_read : std_logic;
	signal rx_fifo_data : std_logic_vector(7 downto 0);

	signal tx_fifo_write  : std_logic;
	signal tx_fifo_commit : std_logic;
	signal tx_fifo_empty  : std_logic;
	signal tx_fifo_data   : std_logic_vector(7 downto 0);
begin
	trashernet_phy_inst : entity trashernet.trashernet_phy_cdc
		generic map(
			F_CLK     => F_CLK,
			F_CLK_PHY => F_CLK_PHY
		)
		port map(
			clk     => clk,
			phy_clk => phy_clk,
			rst     => rst,
			phy_out => phy_out,
			phy_in  => phy_in,
			rx_p    => rx_p,
			tx_p    => tx_p,
			tx_n    => tx_n
		);

	rx_fifo_inst : entity generics.fifo_block
		generic map(
			SIZE => 2047
		)
		port map(
			clk        => clk,
			rst_a      => '0',
			clr        => rst,
			data_in    => phy_out.rx_data,
			write      => phy_out.rx_data_valid,
			commit     => not phy_out.rx_active,
			abort      => '0',
			full       => open,
			data_out   => rx_fifo_data,
			data_first => open,
			empty      => open,
			read       => rx_fifo_read,
			usage      => open
		);

	tx_fifo_inst : entity generics.fifo_block
		generic map(
			SIZE => 2047
		)
		port map(
			clk        => clk,
			rst_a      => '0',
			clr        => rst,
			data_in    => wb_i.dat(7 downto 0),
			write      => tx_fifo_write,
			commit     => tx_fifo_commit,
			abort      => '0',
			full       => open,
			data_out   => tx_fifo_data,
			data_first => open,
			empty      => tx_fifo_empty,
			read       => phy_out.tx_data_ack,
			usage      => open
		);

	wb_adr <= unsigned(wb_i.adr(wb_adr'range));
	wbif : process(clk, rst) is
	begin
		if rst then
			wb_o.ack       <= '0';
			rx_fifo_read   <= '0';
			tx_fifo_write  <= '0';
			tx_fifo_commit <= '0';

		elsif rising_edge(clk) then
			wb_o.ack       <= '0';
			rx_fifo_read   <= '0';
			tx_fifo_write  <= '0';
			tx_fifo_commit <= '0';

			if (wb_i.cyc and wb_i.stb) then
				wb_o.ack <= '1';

				if wb_adr = 0 then
					wb_o.dat <= status_register;
					if wb_o.ack = '0' then
						if wb_i.we = '1' then
							tx_fifo_commit <= '1';
						end if;
					end if;
				else
					wb_o.dat <= (others => '0');

					if wb_o.ack = '0' then
						if wb_i.we = '1' then
							tx_fifo_write <= '1';
						else
							rx_fifo_read <= '1';
						end if;
					end if;
					wb_o.dat(7 downto 0) <= rx_fifo_data;
				end if;
			end if;
		end if;
	end process wbif;

	wb_o.err   <= '0';
	wb_o.rty   <= '1';
	wb_o.stall <= '0';

	phy_in.tx_data_en <= not tx_fifo_empty; -- FIXME: this does not care about inter-packet gaps indicated by `data_first`
	phy_in.tx_data    <= tx_fifo_data;

	status_register <= (x"0000" & x"000" & "000" & phy_out.carrier_detect);
end architecture RTL;