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-- $Id: ibdr_rk11.vhd 317 2010-07-22 19:36:56Z mueller $

--

-- Copyright 2008-2010 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:    ibdr_rk11 - syn

-- Description:    ibus dev(rem): RK11-A/B

--

-- Dependencies:   ram_1swar_gen

-- Test bench:     -

-- Target Devices: generic

-- Tool versions:  xst 8.1, 8.2, 9.1, 9.2; ghdl 0.18-0.25

--

-- Synthesized (xst):

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

-- 2009-06-01   221  10.1.03 K39 xc3s1000-4    46  249   16  148 s  7.1

-- 2008-01-06   111   8.2.03 I34 xc3s1000-4    36  189   16  111 s  6.0

--

-- Revision History: 

-- Date         Rev Version  Comment

-- 2010-06-11   303   1.1    use IB_MREQ.racc instead of RRI_REQ

-- 2009-05-24   219   1.0.9  add CE_MSEC input; inc sector counter every msec

--                           BUGFIX: sector counter now counts 000,...,013.

-- 2009-05-21   217   1.0.8  cancel pending interrupt requests when IE=0

-- 2009-05-16   216   1.0.7  BUGFIX: correct interrupt on IE 0->1 logic

--                           BUGFIX: re-work the seek complete handling

-- 2008-08-22   161   1.0.6  use iblib

-- 2008-05-30   151   1.0.5  BUGFIX: do control reset locally now, add CRDONE

-- 2008-03-30   131   1.0.4  issue interrupt when IDE bit set with GO=0

-- 2008-02-23   118   1.0.3  remove redundant condition in rkda access code

--                           fix bug in control reset logic (we's missing)

-- 2008-01-20   113   1.0.2  Fix busy handling when control reset done

-- 2008-01-20   112   1.0.1  Fix scp handling; use BRESET

-- 2008-01-06   111   1.0    Initial version 

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

library ieee;

use ieee.std_logic_1164.all;

use ieee.std_logic_arith.all;

use work.slvtypes.all;

use work.memlib.all;

use work.iblib.all;

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

entity ibdr_rk11 is                     -- ibus dev(rem): RK11

                                        -- fixed address: 177400

  port (

    CLK : in slbit;                     -- clock

    CE_MSEC : in slbit;                 -- msec pulse

    BRESET : in slbit;                  -- ibus reset

    RRI_LAM : out slbit;                -- remote attention

    IB_MREQ : in ib_mreq_type;          -- ibus request

    IB_SRES : out ib_sres_type;         -- ibus response

    EI_REQ : out slbit;                 -- interrupt request

    EI_ACK : in slbit                   -- interrupt acknowledge

  );

end ibdr_rk11;

architecture syn of ibdr_rk11 is

  constant ibaddr_rk11 : slv16 := conv_std_logic_vector(8#177400#,16);

  constant ibaddr_rkds : slv3 := "000";  -- rkds address offset

  constant ibaddr_rker : slv3 := "001";  -- rker address offset

  constant ibaddr_rkcs : slv3 := "010";  -- rkcs address offset

  constant ibaddr_rkwc : slv3 := "011";  -- rkwc address offset

  constant ibaddr_rkba : slv3 := "100";  -- rkba address offset

  constant ibaddr_rkda : slv3 := "101";  -- rkda address offset

  constant ibaddr_rkmr : slv3 := "110";  -- rkmr address offset

  constant ibaddr_rkdb : slv3 := "111";  -- rkdb address offset

  subtype  rkds_ibf_id      is integer range 15 downto 13;

  constant rkds_ibf_adry  : integer :=  6;

  constant rkds_ibf_scsa  : integer :=  4;

  subtype  rkds_ibf_sc      is integer range  3 downto  0;

  subtype  rker_ibf_he      is integer range 15 downto  5;

  constant rker_ibf_cse   : integer :=  1;

  constant rker_ibf_wce   : integer :=  0;

  constant rkcs_ibf_err   : integer := 15;

  constant rkcs_ibf_he    : integer := 14;

  constant rkcs_ibf_scp   : integer := 13;

  constant rkcs_ibf_maint : integer := 12;

  constant rkcs_ibf_rdy   : integer :=  7;

  constant rkcs_ibf_ide   : integer :=  6;

  subtype  rkcs_ibf_mex     is integer range  5 downto  4;

  subtype  rkcs_ibf_func    is integer range  3 downto  1;

  constant rkcs_ibf_go    : integer :=  0;

  subtype  rkda_ibf_drsel   is integer range 15 downto 13;

  subtype  rkmr_ibf_rid     is integer range 15 downto 13;  -- rem id

  constant rkmr_ibf_crdone: integer := 11;                  -- contr. reset done

  constant rkmr_ibf_sbclr : integer := 10;                  -- clear sbusy's 

  constant rkmr_ibf_creset: integer :=  9;                  -- control reset

  constant rkmr_ibf_fdone : integer :=  8;                  -- func done

  subtype  rkmr_ibf_sdone   is integer range  7 downto  0;  -- seek done

  type state_type is (

    s_idle,

    s_init

  );

  type regs_type is record              -- state registers

    state : state_type;                 -- state

    id : slv3;                          -- rkds: drive id of search done

    sc : slv4;                          -- rkds: sector counter

    cse : slbit;                        -- rker: check sum error

    wce : slbit;                        -- rker: write check error

    he : slbit;                         -- rkcs: hard error

    scp : slbit;                        -- rkcs: seek complete

    maint : slbit;                      -- rkcs: maintenance mode

    rdy   : slbit;                      -- rkcs: control ready

    ide   : slbit;                      -- rkcs: interrupt on done enable

    drsel : slv3;                       -- rkda: currently selected drive

    fireq : slbit;                      -- func done interrupt request flag

    sireq : slv8;                       -- seek done interrupt request flags

    sbusy : slv8;                       -- seek busy flags

    rid   : slv3;                       -- drive id for rem ds reads

    icnt  : slv3;                       -- init state counter

    creset : slbit;                     -- control reset flag

    crdone : slbit;                     -- control reset done since last fdone

  end record regs_type;

  constant regs_init : regs_type := (

    s_init,                             --

    (others=>'0'),                      -- id

    (others=>'0'),                      -- sc

    '0','0',                            -- cse, wce

    '0','0','0',                        -- he, scp, maint

    '1',                                -- rdy (SET TO 1)

    '0',                                -- ide

    (others=>'0'),                      -- drsel

    '0',                                -- fireq

    (others=>'0'),                      -- sireq

    (others=>'0'),                      -- sbusy

    (others=>'0'),                      -- rid

    (others=>'0'),                      -- icnt

    '0','1'                             -- creset, crdone

  );

  signal R_REGS : regs_type := regs_init;

  signal N_REGS : regs_type := regs_init;

  signal MEM_1_WE : slbit := '0';

  signal MEM_0_WE : slbit := '0';

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

  signal MEM_DIN  : slv16 := (others=>'0');

  signal MEM_DOUT : slv16 := (others=>'0');

begin

  MEM_1 : ram_1swar_gen

    generic map (

      AWIDTH => 4,

      DWIDTH => 8)

    port map (

      CLK  => CLK,

      WE   => MEM_1_WE,

      ADDR => MEM_ADDR,

      DI   => MEM_DIN(ibf_byte1),

      DO   => MEM_DOUT(ibf_byte1));

  MEM_0 : ram_1swar_gen

    generic map (

      AWIDTH => 4,

      DWIDTH => 8)

    port map (

      CLK  => CLK,

      WE   => MEM_0_WE,

      ADDR => MEM_ADDR,

      DI   => MEM_DIN(ibf_byte0),

      DO   => MEM_DOUT(ibf_byte0));

  proc_regs: process (CLK)

  begin

    if CLK'event and CLK='1' then

      if BRESET='1' or R_REGS.creset='1' then

        R_REGS <= regs_init;

        if R_REGS.creset = '1' then

          R_REGS.sbusy <= N_REGS.sbusy;

        end if;

      else

        R_REGS <= N_REGS;

      end if;

    end if;

  end process proc_regs;

  proc_next : process (R_REGS, CE_MSEC, IB_MREQ, MEM_DOUT, EI_ACK)

    variable r : regs_type := regs_init;

    variable n : regs_type := regs_init;

    variable ibsel  : slbit := '0';

    variable ibbusy : slbit := '0';

    variable icrip  : slbit := '0';

    variable idout  : slv16 := (others=>'0');

    variable ibrd   : slbit := '0';

    variable ibrem  : slbit := '0';

    variable ibw0   : slbit := '0';

    variable ibw1   : slbit := '0';

    variable ibwrem : slbit := '0';

    variable ilam   : slbit := '0';

    variable iscval : slbit := '0';

    variable iscid : slv3 := (others=>'0');

    variable iei_req : slbit := '0';

    variable imem_we0 : slbit := '0';

    variable imem_we1 : slbit := '0';

    variable imem_addr : slv4 := (others=>'0');

    variable imem_din : slv16 := (others=>'0');

  begin

    r := R_REGS;

    n := R_REGS;

    ibsel  := '0';

    ibbusy := '0';

    icrip  := '0';

    idout  := (others=>'0');

    ibrd   := not IB_MREQ.we;

    ibrem  := IB_MREQ.racc or r.maint;

    ibw0   := IB_MREQ.we and IB_MREQ.be0;

    ibw1   := IB_MREQ.we and IB_MREQ.be1;

    ibwrem := IB_MREQ.we and ibrem;

    ilam   := '0';

    iscval := '0';

    iscid  := (others=>'0');

    iei_req := '0';

    imem_we0  := '0';

    imem_we1  := '0';

    imem_addr := '0' & IB_MREQ.addr(3 downto 1);

    imem_din  := IB_MREQ.din;

    -- ibus address decoder

    if IB_MREQ.req = '1' and

       IB_MREQ.addr(12 downto 4)=ibaddr_rk11(12 downto 4) then

      ibsel := '1';

    end if;

    -- internal state machine (for control reset)

    case r.state is

      when s_idle =>

        null;

      when s_init =>

        ibbusy := ibsel;                -- keep req pending if selected

        ibsel  := '0';                  -- but don't process selection

        icrip  := '1';

        n.icnt := unsigned(r.icnt) + 1;

        if unsigned(r.icnt) = 7 then

          n.state := s_idle;

        end if;

      when others => null;

    end case;

    -- ibus transactions

    if ibsel = '1' then

      idout := MEM_DOUT;

      imem_we0 := ibw0;

      imem_we1 := ibw1;

      case IB_MREQ.addr(3 downto 1) is

        when ibaddr_rkds =>              -- RKDS -- drive status register ----

          if ibrem = '0' then

            imem_addr := '1' & r.drsel;  -- loc read ds data: drsel as addr.

          else

            imem_addr := '1' & r.rid;    -- rem read ds data: rid as addr.

          end if;

          idout(rkds_ibf_id) := r.id;

          if ibrem = '0' then            -- loc ? simulate drive sector monitor

            if r.sc = MEM_DOUT(rkds_ibf_sc) then

              idout(rkds_ibf_scsa) := '1';

            else

              idout(rkds_ibf_scsa) := '0';

            end if;

            idout(rkds_ibf_sc) := r.sc;

          end if;

          if r.sbusy(conv_integer(unsigned(imem_addr(2 downto 0))))='1' then

            idout(rkds_ibf_adry) := '0';             -- clear drive access rdy

          end if;

          if ibwrem = '1' then            -- rem write ? than update ds data

            imem_addr := '1' & IB_MREQ.din(rkds_ibf_id); -- use id field as addr

          else                          -- loc write ?

            imem_we0 := '0';              -- suppress we, is read-only

            imem_we1 := '0';

          end if;

        when ibaddr_rker =>             -- RKER -- error register ------------

          idout(4 downto 2) := (others=>'0');  -- unassigned bits

          idout(rker_ibf_cse) := r.cse; -- use state bits (cleared at go !) 

          idout(rker_ibf_wce) := r.wce;

          if ibwrem = '1' then          -- rem write ?

            if unsigned(IB_MREQ.din(rker_ibf_he)) /= 0 then -- hard errors set ?

              n.he := '1';

            else

              n.he := '0';

            end if;

            n.cse := IB_MREQ.din(rker_ibf_cse); -- mirror cse bit

            n.wce := IB_MREQ.din(rker_ibf_wce); -- mirror wce bit

          else                          -- loc write ?

            imem_we0 := '0';              -- suppress we, is read-only

            imem_we1 := '0';

          end if;

        when ibaddr_rkcs =>             -- RKCS -- control status register ---

          idout(rkcs_ibf_err) := r.he or r.cse or r.wce;

          idout(rkcs_ibf_he)  := r.he;

          idout(rkcs_ibf_scp) := r.scp;

          idout(rkcs_ibf_rdy) := r.rdy;

          idout(rkcs_ibf_go)  := not r.rdy;

          if ibw1 = '1' then

            n.maint := IB_MREQ.din(rkcs_ibf_maint); -- mirror maint bit

          end if;

          if ibw0 = '1' then

            n.ide   := IB_MREQ.din(rkcs_ibf_ide);   -- mirror ide bit

            if n.ide = '0' then                     -- if IE 0 or set to 0

              n.fireq := '0';                         -- cancel all pending

              n.sireq := (others=>'0');               -- interrupt requests

            end if;

            if IB_MREQ.din(rkcs_ibf_go) = '1' then    -- GO=1 ?

              if r.rdy = '1' then                       -- ready and GO ?

                n.scp := '0';                             -- go clears scp !

                n.rdy := '0';                             -- mark busy

                n.cse := '0';                             -- clear soft errors

                n.wce := '0';

                n.fireq := '0';                           -- cancel pend. int

                if unsigned(IB_MREQ.din(rkcs_ibf_func))=0 then -- control reset?

                  n.creset := '1';                        -- handle locally

                else

                  ilam  := '1';                           -- issue lam

                end if;

                if unsigned(IB_MREQ.din(rkcs_ibf_func))=4 or   -- if seek

                   unsigned(IB_MREQ.din(rkcs_ibf_func))=6 then -- or drive reset

                  n.sbusy(conv_integer(unsigned(r.drsel))) := '1'; -- set busy

                end if;

              end if;

            else                                      -- GO=0

              if r.ide = '0' and                        -- if ide now 0

                 IB_MREQ.din(rkcs_ibf_ide)='1' and      -- and is set to 1

                 r.rdy='1' then                         -- and controller ready

                n.fireq := '1';                           -- issue interrupt

              end if;

            end if;

          end if;

        when ibaddr_rkda =>             -- RKDA -- disk address register -----

          if ibrem = '0' then           -- loc access ?

            if r.rdy = '0' then           -- controller busy ?

              imem_we0 := '0';              -- suppress write

              imem_we1 := '0';

            end if;

          end if;

          if imem_we1 = '1' then

            n.drsel := IB_MREQ.din(rkda_ibf_drsel); -- mirror drsel bits

          end if;

        when ibaddr_rkmr =>             -- RKMR -- maintenance register ------

          idout := (others=>'0');

          idout(rkmr_ibf_rid)    := r.rid;

          idout(rkmr_ibf_crdone) := r.crdone;

          idout(rkmr_ibf_sdone)  := r.sbusy;

          if ibwrem = '1' then          -- rem write ?

            n.rid := IB_MREQ.din(rkmr_ibf_rid);

            if r.ide='1' and IB_MREQ.din(rkmr_ibf_sbclr)='0' then

              n.sireq := r.sireq or (IB_MREQ.din(rkmr_ibf_sdone) and r.sbusy);

            end if;

            n.sbusy := r.sbusy and not IB_MREQ.din(rkmr_ibf_sdone);

            if IB_MREQ.din(rkmr_ibf_fdone) = '1' then -- func completed

              n.rdy    := '1';

              n.crdone := '0';

              if r.ide = '1' then

                n.fireq  := '1';

              end if;

            end if;

            if IB_MREQ.din(rkmr_ibf_creset) = '1' then -- control reset

              n.creset := '1';

            end if;

          end if;

        when others =>                  -- all other regs

          null;

      end case;

    end if;

    iscval := '1';

       if r.sireq(7) = '1' then  iscid := "111";

    elsif r.sireq(6) = '1' then  iscid := "110";

    elsif r.sireq(5) = '1' then  iscid := "101";

    elsif r.sireq(4) = '1' then  iscid := "100";

    elsif r.sireq(3) = '1' then  iscid := "011";

    elsif r.sireq(2) = '1' then  iscid := "010";

    elsif r.sireq(1) = '1' then  iscid := "001";

    elsif r.sireq(0) = '1' then  iscid := "000";

    else

      iscval := '0';

    end if;

    if r.ide = '1' then

      if r.fireq='1' or iscval='1' then

        iei_req := '1';

      end if;

    end if;

    if EI_ACK = '1' then                -- interrupt executed

      if r.fireq = '1' then

        n.scp   := '0';                   -- clear scp flag, is command end

        n.fireq := '0';

      elsif iscval = '1' then             -- was a seek done

        n.scp := '1';                     -- signal seek complete interrupt

        n.id := iscid;                        -- load id

        n.sireq(conv_integer(unsigned(iscid))) := '0';  -- reset sireq bit

      end if;

    end if;

    if icrip = '1' then                 -- control reset in progress ?

      imem_addr := '0' & r.icnt;          -- use icnt as addr

      imem_din  := (others=>'0');         -- force data to zero

      imem_we0  := '1';                   -- enable writes

      imem_we1  := '1';

    end if;

    if CE_MSEC = '1' then               -- advance sector counter every msec

      if unsigned(r.sc) = 8#13# then      -- sector counter (count to 8#13#)

        n.sc := (others=>'0');

      else

        n.sc := unsigned(r.sc) + 1;

      end if;

    end if;

    N_REGS <= n;

    MEM_0_WE <= imem_we0;

    MEM_1_WE <= imem_we1;

    MEM_ADDR <= imem_addr;

    MEM_DIN  <= imem_din;

    IB_SRES.dout <= idout;

    IB_SRES.ack  <= ibsel;

    IB_SRES.busy <= ibbusy;

    RRI_LAM <= ilam;

    EI_REQ  <= iei_req;

  end process proc_next;

end syn;