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-- $Id: fx2_2fifoctl_ic.vhd 472 2013-01-06 14:39:10Z mueller $

--

-- Copyright 2012-2013 by Walter F.J. Mueller <W.F.J.Mueller@gsi.de>

--

-- This program is free software; you may redistribute and/or modify it under

-- the terms of the GNU General Public License as published by the Free

-- Software Foundation, either version 2, or at your option any later version.

--

-- This program is distributed in the hope that it will be useful, but

-- WITHOUT ANY WARRANTY, without even the implied warranty of MERCHANTABILITY

-- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

-- for complete details.

-- 

------------------------------------------------------------------------------

-- Module Name:    fx2_2fifoctl_ic - syn

-- Description:    Cypress EZ-USB FX2 driver (2 fifo; int clk)

--

-- Dependencies:   vlib/xlib/iob_reg_o

--                 vlib/xlib/iob_reg_i_gen

--                 vlib/xlib/iob_reg_o_gen

--                 vlib/xlib/iob_reg_io_gen

--                 memlib/fifo_2c_dram

--

-- Test bench:     -

-- Target Devices: generic

-- Tool versions:  xst 13.3; ghdl 0.29

--

-- Synthesized (xst):

-- Date         Rev  ise         Target      flop lutl lutm slic t peri

-- 2013-01-04   469  13.3   O76x xc3s1200e-4  112  172   64  169 s  7.4/7.4

-- 2012-01-14   453  13.3   O76x xc3s1200e-4  101? 173   64  159 s  8.3/7.4

-- 2012-01-08   451  13.3   O76x xc3s1200e-4  110  166   64  163 s  7.5

--

-- Revision History: 

-- Date         Rev Version  Comment

-- 2013-01-04   469   1.2    BUGFIX: redo rx logic, now properly pipelined

-- 2012-01-15   453   1.1    use aempty/afull logic; collapse tx and pe flows

-- 2012-01-09   451   1.0    Initial version

-- 2012-01-01   448   0.5    First draft 

--

------------------------------------------------------------------------------

library ieee;

use ieee.std_logic_1164.all;

use ieee.numeric_std.all;

use work.slvtypes.all;

use work.xlib.all;

use work.memlib.all;

use work.fx2lib.all;

entity fx2_2fifoctl_ic is               -- EZ-USB FX2 driver (2 fifo; int clk)

  generic (

    RXFAWIDTH : positive :=  5;         -- receive  fifo address width

    TXFAWIDTH : positive :=  5;         -- transmit fifo address width

    PETOWIDTH : positive :=  7;         -- packet end time-out counter width

    CCWIDTH :   positive :=  5;         -- chunk counter width

    RXAEMPTY_THRES : natural := 1;      -- threshold for rx aempty flag

    TXAFULL_THRES  : natural := 1);     -- threshold for tx afull flag

  port (

    CLK : in slbit;                     -- clock

    RESET : in slbit := '0';            -- reset

    RXDATA : out slv8;                  -- receive data out

    RXVAL : out slbit;                  -- receive data valid

    RXHOLD : in slbit;                  -- receive data hold

    RXAEMPTY : out slbit;               -- receive almost empty flag

    TXDATA : in slv8;                   -- transmit data in

    TXENA : in slbit;                   -- transmit data enable

    TXBUSY : out slbit;                 -- transmit data busy

    TXAFULL : out slbit;                -- transmit almost full flag

    MONI : out fx2ctl_moni_type;        -- monitor port data

    I_FX2_IFCLK : in slbit;             -- fx2: interface clock

    O_FX2_FIFO : out slv2;              -- fx2: fifo address

    I_FX2_FLAG : in slv4;               -- fx2: fifo flags

    O_FX2_SLRD_N : out slbit;           -- fx2: read enable    (act.low)

    O_FX2_SLWR_N : out slbit;           -- fx2: write enable   (act.low)

    O_FX2_SLOE_N : out slbit;           -- fx2: output enable  (act.low)

    O_FX2_PKTEND_N : out slbit;         -- fx2: packet end     (act.low)

    IO_FX2_DATA : inout slv8            -- fx2: data lines

  );

end fx2_2fifoctl_ic;

architecture syn of fx2_2fifoctl_ic is

  constant c_rxfifo : slv2 := c_fifo_ep4;

  constant c_txfifo : slv2 := c_fifo_ep6;

  constant c_flag_prog   : integer := 0;

  constant c_flag_tx_ff  : integer := 1;

  constant c_flag_rx_ef  : integer := 2;

  constant c_flag_tx2_ff : integer := 3;

  type state_type is (

    s_idle,                             -- s_idle: idle state

    s_rxprep0,                          -- s_rxprep0: switch to rx-fifo

    s_rxprep1,                          -- s_rxprep1: fifo addr setup

    s_rxprep2,                          -- s_rxprep2: wait for flags

    s_rxdisp,                           -- s_rxdisp: read, dispatch

    s_rxpipe,                           -- s_rxpipe: read, pipe wait

    s_txprep0,                          -- s_txprep0: switch to tx-fifo

    s_txprep1,                          -- s_txprep1: fifo addr setup

    s_txprep2,                          -- s_txprep2: wait for flags

    s_txdisp                            -- s_txdisp: write, dispatch

  );

  type regs_type is record

    state : state_type;                 -- state

    petocnt : slv(PETOWIDTH-1 downto 0);  -- pktend time out counter

    pepend : slbit;                     -- pktend pending

    rxpipe1 : slbit;                    -- read pipe 1: iob capture stage

    rxpipe2 : slbit;                    -- read pipe 2: fifo write stage

    ccnt : slv(CCWIDTH-1 downto 0);     -- chunk counter

    moni_ep4_sel : slbit;               -- ep4 (rx) select

    moni_ep6_sel : slbit;               -- ep6 (tx) select

    moni_ep4_pf : slbit;                -- ep4 (rx) prog flag

    moni_ep6_pf : slbit;                -- ep6 (tx) prog flag

  end record regs_type;

  constant petocnt_init : slv(PETOWIDTH-1 downto 0) := (others=>'0');

  constant ccnt_init : slv(CCWIDTH-1 downto 0) := (others=>'0');

  constant regs_init : regs_type := (

    s_idle,                             -- state

    petocnt_init,                       -- petocnt

    '0',                                -- pepend

    '0','0',                            -- rxpipe1, rxpipe2

    ccnt_init,                          -- ccnt

    '0','0',                            -- moni_ep(4|6)_sel

    '0','0'                             -- moni_ep(4|6)_pf

  );

  signal R_REGS : regs_type := regs_init;  -- state registers

  signal N_REGS : regs_type := regs_init;  -- next value state regs

  signal FX2_FIFO     : slv2 := (others=>'0');

  signal FX2_FIFO_CE  : slbit := '0';

  signal FX2_FLAG_N   : slv4 := (others=>'0');

  signal FX2_SLRD_N   : slbit := '1';

  signal FX2_SLWR_N   : slbit := '1';

  signal FX2_SLOE_N   : slbit := '1';

  signal FX2_PKTEND_N : slbit := '1';

  signal FX2_DATA_CEI : slbit := '0';

  signal FX2_DATA_CEO : slbit := '0';

  signal FX2_DATA_OE  : slbit := '0';

  signal RXFIFO_DI  : slv8 := (others=>'0');

  signal RXFIFO_ENA  : slbit := '0';

  signal RXFIFO_BUSY : slbit := '0';

  signal RXSIZE_FX2  : slv(RXFAWIDTH-1 downto 0) := (others=>'0');

  signal RXSIZE_USR  : slv(RXFAWIDTH-1 downto 0) := (others=>'0');

  signal TXFIFO_DO   : slv8 := (others=>'0');

  signal TXFIFO_VAL  : slbit := '0';

  signal TXFIFO_HOLD : slbit := '0';

  signal TXSIZE_FX2  : slv(TXFAWIDTH-1 downto 0) := (others=>'0');

  signal TXSIZE_USR  : slv(TXFAWIDTH-1 downto 0) := (others=>'0');

  signal TXBUSY_L : slbit := '0';

  signal R_MONI_C : fx2ctl_moni_type := fx2ctl_moni_init;

  signal R_MONI_S : fx2ctl_moni_type := fx2ctl_moni_init;

begin

  assert RXAEMPTY_THRES<=2**RXFAWIDTH-1 and

         TXAFULL_THRES<=2**TXFAWIDTH-1

    report "assert((RXAEMPTY|TXAFULL)_THRES <= 2**(RX|TX)FAWIDTH)-1"

    severity failure;

  IOB_FX2_FIFO : iob_reg_o_gen

    generic map (

      DWIDTH => 2,

      INIT   => '0')

    port map (

      CLK => I_FX2_IFCLK,

      CE  => FX2_FIFO_CE,

      DO  => FX2_FIFO,

      PAD => O_FX2_FIFO

    );

  IOB_FX2_FLAG : iob_reg_i_gen

    generic map (

      DWIDTH => 4,

      INIT   => '0')

    port map (

      CLK => I_FX2_IFCLK,

      CE  => '1',

      DI  => FX2_FLAG_N,

      PAD => I_FX2_FLAG

    );

  IOB_FX2_SLRD : iob_reg_o

    generic map (

      INIT   => '1')

    port map (

      CLK => I_FX2_IFCLK,

      CE  => '1',

      DO  => FX2_SLRD_N,

      PAD => O_FX2_SLRD_N

    );

  IOB_FX2_SLWR : iob_reg_o

    generic map (

      INIT   => '1')

    port map (

      CLK => I_FX2_IFCLK,

      CE  => '1',

      DO  => FX2_SLWR_N,

      PAD => O_FX2_SLWR_N

    );

  IOB_FX2_SLOE : iob_reg_o

    generic map (

      INIT   => '1')

    port map (

      CLK => I_FX2_IFCLK,

      CE  => '1',

      DO  => FX2_SLOE_N,

      PAD => O_FX2_SLOE_N

    );

  IOB_FX2_PKTEND : iob_reg_o

    generic map (

      INIT   => '1')

    port map (

      CLK => I_FX2_IFCLK,

      CE  => '1',

      DO  => FX2_PKTEND_N,

      PAD => O_FX2_PKTEND_N

    );

  IOB_FX2_DATA : iob_reg_io_gen

    generic map (

      DWIDTH => 8,

      PULL   => "KEEP")

    port map (

      CLK => I_FX2_IFCLK,

      CEI => FX2_DATA_CEI,

      CEO => FX2_DATA_CEO,

      OE  => FX2_DATA_OE,

      DI  => RXFIFO_DI,                 -- input data   (read from pad)

      DO  => TXFIFO_DO,                 -- output data  (write  to pad)

      PAD => IO_FX2_DATA

    );

  RXFIFO : fifo_2c_dram                -- input fifo, 2 clock, dram based

    generic map (

      AWIDTH => RXFAWIDTH,

      DWIDTH => 8)

    port map (

      CLKW   => I_FX2_IFCLK,

      CLKR   => CLK,

      RESETW => '0',

      RESETR => RESET,

      DI     => RXFIFO_DI,

      ENA    => RXFIFO_ENA,

      BUSY   => RXFIFO_BUSY,

      DO     => RXDATA,

      VAL    => RXVAL,

      HOLD   => RXHOLD,

      SIZEW  => RXSIZE_FX2,

      SIZER  => RXSIZE_USR

    );

  TXFIFO : fifo_2c_dram                -- output fifo, 2 clock, dram based

    generic map (

      AWIDTH => TXFAWIDTH,

      DWIDTH => 8)

    port map (

      CLKW   => CLK,

      CLKR   => I_FX2_IFCLK,

      RESETW => RESET,

      RESETR => '0',

      DI     => TXDATA,

      ENA    => TXENA,

      BUSY   => TXBUSY_L,

      DO     => TXFIFO_DO,

      VAL    => TXFIFO_VAL,

      HOLD   => TXFIFO_HOLD,

      SIZEW  => TXSIZE_USR,

      SIZER  => TXSIZE_FX2

    );

  proc_regs: process (I_FX2_IFCLK)

  begin

    if rising_edge(I_FX2_IFCLK) then

      if RESET = '1' then

        R_REGS <= regs_init;

      else

        R_REGS <= N_REGS;

      end if;

    end if;

  end process proc_regs;

  proc_next: process (R_REGS,

                      FX2_FLAG_N, TXFIFO_VAL, RXSIZE_FX2,

                      RXFIFO_BUSY, TXBUSY_L)

    variable r : regs_type := regs_init;

    variable n : regs_type := regs_init;

    variable ififo_ce : slbit := '0';

    variable ififo    : slv2 := "00";

    variable irxfifo_ena  : slbit := '0';

    variable itxfifo_hold : slbit := '0';

    variable islrd   : slbit := '0';

    variable islwr   : slbit := '0';

    variable isloe   : slbit := '0';

    variable ipktend : slbit := '0';

    variable idata_cei : slbit := '0';

    variable idata_ceo : slbit := '0';

    variable idata_oe  : slbit := '0';

    variable slrxok : slbit := '0';

    variable sltxok : slbit := '0';

    variable pipeok : slbit := '0';

    variable cc_clr : slbit := '0';

    variable cc_cnt : slbit := '0';

    variable cc_done : slbit := '0';

  begin

    r := R_REGS;

    n := R_REGS;

    ififo_ce := '0';

    ififo    := "00";

    irxfifo_ena  := '0';

    itxfifo_hold := '1';

    islrd   := '0';

    islwr   := '0';

    isloe   := '0';

    ipktend := '0';

    idata_cei := '0';

    idata_ceo := '0';

    idata_oe  := '0';

    slrxok := FX2_FLAG_N(c_flag_rx_ef); -- empty flag is act.low!

    sltxok := FX2_FLAG_N(c_flag_tx_ff); --  full flag is act.low!

    pipeok := FX2_FLAG_N(c_flag_prog);  -- almost flag is act.low!

    cc_clr := '0';

    cc_cnt := '0';

    if unsigned(r.ccnt) = 0  then

      cc_done := '1';

    else

      cc_done := '0';

    end if;

    n.rxpipe1  := '0';

    case r.state is

      when s_idle =>                    -- s_idle:

        if slrxok='1' and RXFIFO_BUSY='0' then

          ififo_ce := '1';

          ififo    := c_rxfifo;

          n.state := s_rxprep1;

        elsif sltxok='1' and (TXFIFO_VAL='1' or r.pepend='1')then

          ififo_ce := '1';

          ififo    := c_txfifo;

          n.state := s_txprep1;

        end if;

      when s_rxprep0 =>                 -- s_rxprep0: switch to rx-fifo

        ififo_ce := '1';

        ififo    := c_rxfifo;

        n.state := s_rxprep1;

      when s_rxprep1 =>                 -- s_rxprep1: fifo addr setup

        cc_clr  := '1';

        n.state := s_rxprep2;

      when s_rxprep2 =>                 -- s_rxprep2: wait for flags

        isloe   := '1';

        n.state := s_rxdisp;

      when s_rxdisp =>                  -- s_rxdisp: read, dispatch

        isloe := '1';

        -- if chunk done and tx or pe pending and possible

        if cc_done='1' and sltxok='1' and (TXFIFO_VAL='1' or r.pepend='1') then

          if r.rxpipe1='1' or r.rxpipe2='1' then -- rx pipe busy ?

            n.state := s_rxdisp;            -- wait

          else

            n.state := s_txprep0;           -- otherwise switch to tx flow

          end if;

        -- if more rx to do and possible

        elsif slrxok='1' and unsigned(RXSIZE_FX2)>3 then  -- !thres must be >3!

          islrd := '1';

          cc_cnt := '1';

          n.rxpipe1 := '1';

          if pipeok='1' then

            n.state := s_rxdisp;             -- 1 cycle read

            --n.state := s_rxprep2;            -- 2 cycle read

          else

            n.state := s_rxpipe;

          end if;

        -- otherwise back to idle

        else

          if r.rxpipe1='1' or r.rxpipe2='1' then -- rx pipe busy ?

            n.state := s_rxdisp;            -- wait

          else

            n.state := s_idle;              -- to idle

          end if;

        end if;

      when s_rxpipe =>                  -- s_rxpipe:  read, pipe wait

        isloe := '1';

        n.state := s_rxprep2;

      when s_txprep0 =>                 -- s_txprep0: switch to tx-fifo

        ififo_ce := '1';

        ififo    := c_txfifo;

        n.state := s_txprep1;

      when s_txprep1 =>                 -- s_txprep1: fifo addr setup

        cc_clr  := '1';

        n.state := s_txprep2;

      when s_txprep2 =>                 -- s_txprep2: wait for flags

        n.state := s_txdisp;

      when s_txdisp =>                  -- s_txdisp: write, dispatch

        -- if chunk done and rx pending and possible

        if cc_done='1' and slrxok='1' and RXFIFO_BUSY='0' then

          n.state := s_rxprep0;

        -- if pktend to do and possible

        elsif sltxok = '1' and r.pepend = '1' then

          ipktend  := '1';

          n.pepend := '0';

          n.state := s_idle;

        -- if more tx to do and possible

        elsif sltxok = '1' and TXFIFO_VAL = '1' then

          cc_cnt := '1';                  -- inc chunk count

          n.pepend := '0';                -- cancel pe (avoid back-2-back tx+pe)

          itxfifo_hold := '0';

          idata_ceo := '1';

          idata_oe  := '1';

          islwr     := '1';

          if pipeok = '1' then           -- if not almost full

            n.state   := s_txdisp;          -- stream 

          else

            n.state   := s_txprep1;         -- wait for full flag

          end if;

        -- otherwise back to idle

        else

          n.state := s_idle;

        end if;

      when others => null;

    end case;

    -- rx pipe handling

    idata_cei   := r.rxpipe1;

    n.rxpipe2   := r.rxpipe1;

    irxfifo_ena := r.rxpipe2;

    -- chunk counter handling

    if cc_clr = '1' then

      n.ccnt := (others=>'1');

    elsif cc_cnt='1' and unsigned(r.ccnt) > 0 then

      n.ccnt := slv(unsigned(r.ccnt) - 1);

    end if;

    -- pktend time-out handling:

    --   if tx fifo is non-empty, set counter to max

    --   if tx fifo is empty, count down every usec

    --   on 1->0 transition queue pktend request

    if TXFIFO_VAL = '1' then

      n.petocnt := (others=>'1');

    else

      if unsigned(r.petocnt) /= 0 then

        n.petocnt := slv(unsigned(r.petocnt) - 1);

        if unsigned(r.petocnt) = 1 then

          n.pepend := '1';

        end if;

      end if;

    end if;

    n.moni_ep4_sel := '0';

    n.moni_ep6_sel := '0';

    if r.state = s_rxdisp or r.state = s_rxpipe then

      n.moni_ep4_sel := '1';

      n.moni_ep4_pf  := not FX2_FLAG_N(c_flag_prog);

    elsif r.state = s_txdisp then

      n.moni_ep6_sel := '1';

      n.moni_ep6_pf  := not FX2_FLAG_N(c_flag_prog);

    end if;

    N_REGS <= n;

    FX2_FIFO_CE  <= ififo_ce;

    FX2_FIFO     <= ififo;

    FX2_SLRD_N   <= not islrd;

    FX2_SLWR_N   <= not islwr;

    FX2_SLOE_N   <= not isloe;

    FX2_PKTEND_N <= not ipktend;

    FX2_DATA_CEI <= idata_cei;

    FX2_DATA_CEO <= idata_ceo;

    FX2_DATA_OE  <= idata_oe;

    RXFIFO_ENA   <= irxfifo_ena;

    TXFIFO_HOLD  <= itxfifo_hold;

  end process proc_next;

  proc_moni: process (CLK)

  begin

    if rising_edge(CLK) then

      if RESET = '1' then

        R_MONI_C <= fx2ctl_moni_init;

        R_MONI_S <= fx2ctl_moni_init;

      else

        R_MONI_C <= fx2ctl_moni_init;

        R_MONI_C.fifo_ep4        <= R_REGS.moni_ep4_sel;

        R_MONI_C.fifo_ep6        <= R_REGS.moni_ep6_sel;

        R_MONI_C.flag_ep4_empty  <= not FX2_FLAG_N(c_flag_rx_ef);

        R_MONI_C.flag_ep4_almost <= R_REGS.moni_ep4_pf;

        R_MONI_C.flag_ep6_full   <= not FX2_FLAG_N(c_flag_tx_ff);

        R_MONI_C.flag_ep6_almost <= R_REGS.moni_ep6_pf;

        R_MONI_C.slrd            <= not FX2_SLRD_N;

        R_MONI_C.slwr            <= not FX2_SLWR_N;

        R_MONI_C.pktend          <= not FX2_PKTEND_N;

        R_MONI_S <= R_MONI_C;

      end if;

    end if;

  end process proc_moni;

  proc_almost: process (RXSIZE_USR, TXSIZE_USR)

  begin

    -- rxsize_usr is the number of bytes to read

    -- txsize_usr is the number of bytes to write

    if unsigned(RXSIZE_USR) <= RXAEMPTY_THRES then

      RXAEMPTY <= '1';

    else

      RXAEMPTY <= '0';

    end if;

    if unsigned(TXSIZE_USR) <= TXAFULL_THRES then

      TXAFULL <= '1';

    else

      TXAFULL <= '0';

    end if;

  end process proc_almost;

  TXBUSY <= TXBUSY_L;

  MONI <= R_MONI_S;

end syn;