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

--  This file is a part of the LEON VHDL model

--  Copyright (C) 1999  European Space Agency (ESA)

--

--  This library is free software; you can redistribute it and/or

--  modify it under the terms of the GNU Lesser General Public

--  License as published by the Free Software Foundation; either

--  version 2 of the License, or (at your option) any later version.

--

--  See the file COPYING.LGPL for the full details of the license.

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

-- Entity:      dcache

-- File:        dcache.vhd

-- Author:      Jiri Gaisler - Gaisler Research

-- Description: This unit implements the data cache controller.

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

library IEEE;

use IEEE.std_logic_1164.all;

use IEEE.std_logic_unsigned."+";

use IEEE.std_logic_unsigned.conv_integer;

use IEEE.std_logic_arith.conv_unsigned;

use work.amba.all;

use work.leon_target.all;

use work.leon_config.all;

use work.sparcv8.all;           -- ASI declarations

use work.leon_iface.all;

use work.macro.all;             -- xorv()

entity dcache is

  port (

    rst : in  std_logic;

    clk : in  clk_type;

    dci : in  dcache_in_type;

    dco : out dcache_out_type;

    ico : in  icache_out_type;

    mcdi : out memory_dc_in_type;

    mcdo : in  memory_dc_out_type;

    ahbsi : in  ahb_slv_in_type;

    dcrami : out dcram_in_type;

    dcramo : in  dcram_out_type;

    fpuholdn : in  std_logic

);

end;

architecture rtl of dcache is

constant TAG_HIGH   : integer := DTAG_HIGH;

constant TAG_LOW    : integer := DOFFSET_BITS + DLINE_BITS + 2;

constant OFFSET_HIGH: integer := TAG_LOW - 1;

constant OFFSET_LOW : integer := DLINE_BITS + 2;

constant LINE_HIGH  : integer := OFFSET_LOW - 1;

constant LINE_LOW   : integer := 2;

constant LINE_ZERO  : std_logic_vector(DLINE_BITS-1 downto 0) := (others => '0');

constant SETBITS : integer := log2x(DSETS);

type rdatatype is (dtag, ddata, dddata, icache, memory);  -- sources during cache read

type vmasktype is (clearone, clearall, merge, tnew);    -- valid bits operation

type write_buffer_type is record                        -- write buffer 

  addr, data1, data2 : std_logic_vector(31 downto 0);

  size : std_logic_vector(1 downto 0);

  asi  : std_logic_vector(3 downto 0);

  read : std_logic;

  lock : std_logic;

end record;

type dcache_control_type is record                      -- all registers

  read : std_logic;                                     -- access direction

  signed : std_logic;                                   -- signed/unsigned read

  size : std_logic_vector(1 downto 0);                   -- access size

  req, burst, holdn, nomds, stpend  : std_logic;

  xaddress : std_logic_vector(31 downto 0);              -- common address buffer

  faddr : std_logic_vector(DOFFSET_BITS - 1 downto 0);   -- flush address

  valid : std_logic_vector(DLINE_SIZE - 1 downto 0);     -- registered valid bits

  dstate : std_logic_vector(2 downto 0);                 -- FSM vector

  hit : std_logic;

  flush         : std_logic;                            -- flush in progress

  mexc          : std_logic;                            -- latched mexc

  wb            : write_buffer_type;                    -- write buffer

  asi           : std_logic_vector(3 downto 0);

  icenable      : std_logic;                            -- icache diag access

  rndcnt        : std_logic_vector(log2x(DSETS)-1 downto 0); -- replace counter

  setrepl       : std_logic_vector(log2x(DSETS)-1 downto 0); -- set to replace

  lrr           : std_logic;

  dsuset        : std_logic_vector(log2x(DSETS)-1 downto 0);

  lock          : std_logic;

  lramrd : std_logic;

end record;

type snoop_reg_type is record                   -- snoop control registers

  snoop   : std_logic;                          -- snoop access to tags

  writebp : std_logic_vector(0 to DSETS-1);              -- snoop write bypass

  addr    : std_logic_vector(TAG_HIGH downto OFFSET_LOW);-- snoop tag

end record;

type snoop_hit_bits_type is array (0 to 2**DOFFSET_BITS-1) of std_logic_vector(0 to DSETS-1);

type snoop_hit_reg_type is record

  hit     : snoop_hit_bits_type;                              -- snoop hit bits  

  taddr   : std_logic_vector(OFFSET_HIGH downto OFFSET_LOW);  -- saved tag address

  set     : std_logic_vector(log2x(DSETS)-1 downto 0);        -- saved set

end record;

subtype lru_type is std_logic_vector(DLRUBITS-1 downto 0);

type lru_array  is array (0 to 2**DOFFSET_BITS-1) of lru_type;  -- lru registers

type par_type is array (0 to DSETS-1) of std_logic_vector(1 downto 0);

type lru_reg_type is record

  write : std_logic;

  waddr : std_logic_vector(DOFFSET_BITS-1 downto 0);

  set   :  std_logic_vector(SETBITS-1 downto 0); --integer range 0 to DSETS-1;

  lru   : lru_array;

end record;

subtype lock_type is std_logic_vector(0 to DSETS-1);

function lru_set (lru : lru_type; lock : lock_type) return std_logic_vector is

variable xlru : std_logic_vector(4 downto 0);

variable set  : std_logic_vector(SETBITS-1 downto 0);

variable xset : std_logic_vector(1 downto 0);

variable unlocked : integer range 0 to DSETS-1;

begin

  set := (others => '0'); xlru := (others => '0');

  xlru(DLRUBITS-1 downto 0) := lru;

  if DCLOCK_BIT = 1 then

    unlocked := DSETS-1;

    for i in DSETS-1 downto 0 loop

      if lock(i) = '0' then unlocked := i; end if;

    end loop;

  end if;

  case DSETS is

  when 2 =>

    if DCLOCK_BIT = 1 then

      if lock(0) = '1' then xset(0) := '1'; else xset(0) := xlru(0); end if;

    else xset(0) := xlru(0); end if;

  when 3 =>

    if DCLOCK_BIT = 1 then

      xset := std_logic_vector(conv_unsigned(lru3_repl_table(conv_integer(xlru)) (unlocked), 2));

    else

      xset := std_logic_vector(conv_unsigned(lru3_repl_table(conv_integer(xlru)) (0), 2));

    end if;

  when 4 =>

    if DCLOCK_BIT = 1 then

      xset := std_logic_vector(conv_unsigned(lru4_repl_table(conv_integer(xlru)) (unlocked), 2));

    else

      xset := std_logic_vector(conv_unsigned(lru4_repl_table(conv_integer(xlru)) (0), 2));

    end if;

  when others =>

  end case;

  set := xset(SETBITS-1 downto 0);

  return(set);

end;

function lru_calc (lru : lru_type; set : integer) return lru_type is

variable new_lru : lru_type;

variable xnew_lru: std_logic_vector(4 downto 0);

variable xlru : std_logic_vector(4 downto 0);

begin

  new_lru := (others => '0'); xnew_lru := (others => '0');

  xlru := (others => '0'); xlru(DLRUBITS-1 downto 0) := lru;

  case DSETS is

  when 2 =>

    if set = 0 then xnew_lru(0) := '1'; else xnew_lru(0) := '0'; end if;

  when 3 =>

    xnew_lru(2 downto 0) := lru_3set_table(conv_integer(lru))(set);

  when 4 =>

    xnew_lru(4 downto 0) := lru_4set_table(conv_integer(lru))(set);

  when others =>

  end case;

  new_lru := xnew_lru(DLRUBITS-1 downto 0);

  return(new_lru);

end;

subtype word is std_logic_vector(31 downto 0);

signal r, c : dcache_control_type;      -- r is registers, c is combinational

signal rs, cs : snoop_reg_type;         -- rs is registers, cs is combinational

signal rh, ch : snoop_hit_reg_type;     -- rs is registers, cs is combinational

signal rl, cl : lru_reg_type;           -- rl is registers, cl is combinational

begin

  dctrl : process(rst, r, rs, rh, rl, dci, mcdo, ico, dcramo, ahbsi, fpuholdn)

  type ddtype is array (0 to DSETS-1) of word;

  variable dcramov : dcram_out_type;

  variable rdatasel : rdatatype;

  variable maddress : std_logic_vector(31 downto 0);

  variable maddrlow : std_logic_vector(1 downto 0);

  variable edata : std_logic_vector(31 downto 0);

  variable size : std_logic_vector(1 downto 0);

  variable read : std_logic;

  variable twrite, tdiagwrite, ddiagwrite, dwrite : std_logic;

  variable taddr : std_logic_vector(OFFSET_HIGH  downto LINE_LOW); -- tag address

  variable newtag : std_logic_vector(TAG_HIGH  downto TAG_LOW); -- new tag

  variable align_data : std_logic_vector(31 downto 0); -- aligned data

  variable ddatain : std_logic_vector(31 downto 0);

  variable ddatainv, rdatav, align_datav : ddtype;

  variable rdata : std_logic_vector(31 downto 0);

  variable vmaskraw, vmask : std_logic_vector((DLINE_SIZE -1) downto 0);

  variable ivalid : std_logic_vector((DLINE_SIZE -1) downto 0);

  variable vmaskdbl : std_logic_vector((DLINE_SIZE/2 -1) downto 0);

  variable enable : std_logic;

  variable mds : std_logic;

  variable mexc : std_logic;

  variable hit, valid, validraw, forcemiss : std_logic;

  variable signed   : std_logic;

  variable flush    : std_logic;

  variable iflush   : std_logic;

  variable v : dcache_control_type;

  variable eholdn : std_logic;                          -- external hold

  variable snoopwe  : std_logic;

  variable hcache   : std_logic;

  variable lramcs, lramen, lramrd, lramwr  : std_logic;

  variable snoopaddr: std_logic_vector(OFFSET_HIGH downto OFFSET_LOW);

  variable vs : snoop_reg_type;

  variable vh : snoop_hit_reg_type;

  variable dsudata   : std_logic_vector(31 downto 0);

  variable set : integer range 0 to DSETS-1;

  variable ddset : integer range 0 to MAXSETS-1;

  variable snoopset : integer range 0 to DSETS-1;

  variable validv, hitv, validrawv : std_logic_vector(0 to MAXSETS-1);

  variable csnoopwe : std_logic_vector(0 to MAXSETS-1);

  variable ctwrite, cdwrite : std_logic_vector(0 to MAXSETS-1);

  variable vset, setrepl  : std_logic_vector(log2x(DSETS)-1 downto 0);

  variable wlrr : std_logic_vector(0 to MAXSETS-1);

  variable vl : lru_reg_type;

  variable diagset : std_logic_vector(TAG_LOW + SETBITS -1 downto TAG_LOW);

  variable lock : std_logic_vector(0 to DSETS-1);

  variable wlock : std_logic_vector(0 to MAXSETS-1);

  variable snoophit : std_logic_vector(0 to DSETS-1);

  variable snoopval : std_logic;

  variable snoopset2, rdsuset : integer range 0 to DSETS-1;

  variable laddr : std_logic_vector(31  downto 0); -- local ram addr

  begin

-- init local variables

    v := r; vs := rs; vh := rh; dcramov := dcramo; vl := rl;

    vl.write := '0'; lramen := '0'; lramrd := '0'; lramwr := '0';

    lramcs := '0'; laddr := (others => '0'); v.lramrd := '0';

    mds := '1'; dwrite := '0'; twrite := '0';

    ddiagwrite := '0'; tdiagwrite := '0'; v.holdn := '1'; mexc := '0';

    flush := '0'; v.icenable := '0'; iflush := '0';

    eholdn := ico.hold and fpuholdn; ddset := 0; vset := (others => '0');

    vs.snoop := '0'; vs.writebp := (others => '0'); snoopwe := '0';

    snoopaddr := ahbsi.haddr(OFFSET_HIGH downto OFFSET_LOW);

    hcache := '0'; rdsuset := 0; enable := '1';

    validv := (others => '0'); validrawv := (others => '0');

    hitv := (others => '0'); ivalid := (others => '0');

    rdatasel := ddata;  -- read data from cache as default

    set := 0; snoopset := 0;  csnoopwe := (others => '0');

    ctwrite := (others => '0'); cdwrite := (others => '0');

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

    for i in 0 to DSETS-1 loop wlock(i) := dcramov.dtramout(i).lock; end loop;

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

    for i in 0 to 1 loop wlrr(i) := dcramov.dtramout(i).lrr; end loop;

    if (DSETS > 1) then setrepl := r.setrepl; else setrepl := (others => '0'); end if;

-- random replacement counter

    if DSETS > 1 then

-- pragma translate_off

      if not is_x(r.rndcnt) then

-- pragma translate_on

        if conv_integer(r.rndcnt) = (DSETS - 1) then v.rndcnt := (others => '0');

        else v.rndcnt := r.rndcnt + 1; end if;

-- pragma translate_off

      end if;

-- pragma translate_on

    end if;

-- generate lock bits

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

    if DCLOCK_BIT = 1 then

      for i in 0 to DSETS-1 loop lock(i) := dcramov.dtramout(i).lock; end loop;

    end if;

-- AHB snoop handling

    if DSNOOP then

      -- snoop only in cacheable areas

--      for i in PROC_CACHETABLE'range loop     --'

--        if (ahbsi.haddr(31 downto 32-PROC_CACHE_ADDR_MSB) >= PROC_CACHETABLE(i).firstaddr) and

--           (ahbsi.haddr(31 downto 32-PROC_CACHE_ADDR_MSB) < PROC_CACHETABLE(i).lastaddr) 

--        then hcache := '1';  end if;

--      end loop;

        hcache := is_cacheable(ahbsi.haddr(31 downto 24));

      -- snoop on NONSEQ or SEQ and first word in cache line

      -- do not snoop during own transfers or during cache flush

      if (ahbsi.hready and ahbsi.hwrite and not mcdo.bg) = '1' and

         ((ahbsi.htrans = HTRANS_NONSEQ) or

            ((ahbsi.htrans = HTRANS_SEQ) and

             (ahbsi.haddr(LINE_HIGH downto LINE_LOW) = LINE_ZERO)))

      then

        vs.snoop := mcdo.dsnoop and hcache;

        vs.addr := ahbsi.haddr(TAG_HIGH downto OFFSET_LOW);

      end if;

      -- clear valid bits on snoop hit (or set hit bits)

      for i in DSETS-1 downto 0 loop

        if ((rs.snoop and (not mcdo.ba) and not r.flush) = '1')

          and (dcramov.dtramoutsn(i).tag = rs.addr(TAG_HIGH downto TAG_LOW))

        then

          if DSNOOP_FAST then

-- pragma translate_off

            if not is_x(rs.addr(OFFSET_HIGH downto OFFSET_LOW)) then

-- pragma translate_on

            vh.hit(conv_integer(rs.addr(OFFSET_HIGH downto OFFSET_LOW)))(i) := '1';

--             vh.set := std_logic_vector(conv_unsigned(i, SETBITS));

-- pragma translate_off

            end if;

-- pragma translate_on

          else

            snoopaddr := rs.addr(OFFSET_HIGH downto OFFSET_LOW);

            snoopwe := '1'; snoopset := i;

          end if;

        end if;

      -- bypass tag data on read/write contention

        if (not DSNOOP_FAST) and (rs.writebp(i) = '1') then

          dcramov.dtramout(i).tag   := rs.addr(TAG_HIGH downto TAG_LOW);

          dcramov.dtramout(i).valid := (others => '0');

        end if;

      end loop;

    end if;

-- generate access parameters during pipeline stall

    if ((r.holdn) = '0') or (DEBUG_UNIT and (dci.dsuen = '1')) then

      taddr := r.xaddress(OFFSET_HIGH downto LINE_LOW);

      --if r.dsuwren = '0' then v.dsuwren := '1'; end if;

    elsif ((dci.enaddr and not dci.read) = '1') or (eholdn = '0')

    then

      taddr := dci.maddress(OFFSET_HIGH downto LINE_LOW);

    else

      taddr := dci.eaddress(OFFSET_HIGH downto LINE_LOW);

    end if;

    if (dci.write or not r.holdn) = '1' then

      maddress := r.xaddress(31 downto 0); signed := r.signed;

      read := r.read; size := r.size; edata := dci.maddress;

    else

      maddress := dci.maddress(31 downto 0); signed := dci.signed;

      read := dci.read; size := dci.size; edata := dci.edata;

    end if;

    newtag := dci.maddress(TAG_HIGH downto TAG_LOW);

    vl.waddr := maddress(OFFSET_HIGH downto OFFSET_LOW);  -- lru write address

-- generate cache hit and valid bits

    forcemiss := not dci.asi(3); hit := '0'; set := 0; snoophit := (others => '0');

    snoopval := '1';

    for i in DSETS-1 downto 0 loop

      if DSNOOP and DSNOOP_FAST then

-- pragma translate_off

        if not is_x(rh.taddr) then

-- pragma translate_on        

          snoophit(i) := rh.hit(conv_integer(rh.taddr))(i);

-- pragma translate_off

        end if;

-- pragma translate_on

      end if;

      if (dcramov.dtramout(i).tag = dci.maddress(TAG_HIGH downto TAG_LOW))

      then hitv(i) := '1'; end if; -- not r.flush; set := i; end if;

      validrawv(i) := hitv(i) and (not r.flush) and (not snoophit(i)) and

        genmux(dci.maddress(LINE_HIGH downto LINE_LOW), dcramov.dtramout(i).valid);

      validv(i) :=  validrawv(i);

      if (hitv(i) and not snoophit(i)) = '1' then ivalid := ivalid or dcramov.dtramout(i).valid; end if;

      snoopval := snoopval and not snoophit(i);

    end loop;

    hit := orv(hitv) and not r.flush; validraw := orv(validrawv);

    valid := orv(validv);

    if DSETS > 1 then

      for i in DSETS-1 downto 0 loop

        if (hitv(i) = '1') then

          vset := vset or std_logic_vector(conv_unsigned(i, SETBITS));

        end if;

      end loop;

      set := conv_integer(vset);

    else set := 0; end if;

    if (dci.dsuen and (not r.holdn)) = '1' then diagset := r.xaddress(TAG_LOW+SETBITS-1 downto TAG_LOW);

    else diagset := maddress(TAG_LOW + SETBITS - 1 downto TAG_LOW); end if;

-- pragma translate_off

    if not is_x(diagset) then

-- pragma translate_on

      case DSETS is

      when 1 => ddset := 0;

      when 3 => if conv_integer(diagset) < 3 then ddset := conv_integer(diagset); end if;

      when others => ddset := conv_integer(diagset);

      end case;

-- pragma translate_off

    end if;

--pragma translate_on

    if ((r.holdn and dci.enaddr) = '1')  and (r.dstate = "000") then

        v.hit := hit; v.xaddress := dci.maddress;

        v.read := dci.read; v.size := dci.size;

        v.asi := dci.asi(3 downto 0);

        v.signed := dci.signed;

    end if;

-- Store buffer

--    wdata := r.wb.data1;

    if mcdo.ready = '1' then

      v.wb.addr(2) := r.wb.addr(2) or (r.wb.size(0) and r.wb.size(1));

      if r.stpend = '1' then

        v.stpend := r.req; v.wb.data1 := r.wb.data2;

        v.wb.lock := r.wb.lock and r.req;

      end if;

    end if;

    if mcdo.grant = '1' then v.req := r.burst; v.burst := '0'; end if;

    if (LOCAL_RAM) then

      if ((r.holdn) = '0') or (DEBUG_UNIT and (dci.dsuen = '1')) then

        laddr := r.xaddress;

      elsif ((dci.enaddr and not dci.read) = '1') or (eholdn = '0') then

        laddr := dci.maddress;

      else laddr := dci.eaddress; end if;

      if  (dci.enaddr = '1') and (dci.maddress(31 downto 24) = LOCAL_RAM_START)

      then lramen := '1'; end if;

      if  ((dci.eenaddr or dci.enaddr) = '1') and (laddr(31 downto 24) = LOCAL_RAM_START)

      then lramcs := '1'; end if;

    end if;

-- main Dcache state machine

    case r.dstate is

    when "000" =>                       -- Idle state

      v.nomds := r.nomds and not eholdn;

      if (snoopval = '1') then v.valid := dcramov.dtramout(set).valid;

      else v.valid := (others => '0'); end if;

      if (r.stpend  = '0') or ((mcdo.ready and not r.req)= '1') then -- wait for store queue

        v.wb.addr := dci.maddress; v.wb.size := dci.size;

        v.wb.read := dci.read; v.wb.data1 := dci.edata; v.wb.lock := dci.lock;

        v.wb.asi := dci.asi(3 downto 0);

      end if;

      if (eholdn and (not r.nomds)) = '1' then -- avoid false path through nullify

        if dci.asi(3 downto 0) = LASI_DTAG then rdatasel := dtag; end if;

        if dci.asi(3 downto 0) = LASI_DDATA then rdatasel := dddata; end if;

      end if;

      if (dci.enaddr and eholdn and (not r.nomds) and not dci.nullify) = '1' then

        case dci.asi(3 downto 0) is

        when LASI_ITAG | LASI_IDATA =>          -- Read/write Icache tags

          if ico.flush = '1' then mexc := '1';

         else v.dstate := "101"; v.holdn := '0'; end if;

        when LASI_IFLUSH =>             -- flush instruction cache

          if dci.read = '0' then iflush := '1'; end if;

        when LASI_DFLUSH =>             -- flush data cache

          if dci.read = '0' then flush := '1'; end if;

        when LASI_DDATA =>              -- Read/write Dcache data

          if (dci.size /= "10") or (r.flush = '1') then -- only word access is allowed

            mexc := '1';

          elsif (dci.read = '0') then

            dwrite := '1'; ddiagwrite := '1';

          end if;

        when LASI_DTAG =>               -- Read/write Dcache tags

          if (dci.size /= "10") or (r.flush = '1') then -- allow only word access

            mexc := '1';

          elsif (dci.read = '0') then

            twrite := '1'; tdiagwrite := '1';

          end if;

        when others =>

--          setrepl := std_logic_vector(conv_unsigned(set, SETBITS));

          if dci.read = '1' then        -- read access

            if LOCAL_RAM and (lramen = '1') then

              lramrd := '1';

            elsif (not ((mcdo.dcs(0) = '1')

               and ((hit and valid and not forcemiss) = '1')))

            then        -- read miss

              v.holdn := '0'; v.dstate := "001";

              if ((r.stpend  = '0') or ((mcdo.ready and not r.req) = '1'))

              then      -- wait for store queue

                v.req := '1';

                v.burst := dci.size(1) and dci.size(0) and not dci.maddress(2);

              end if;

            else       -- read hit

              if (DSETS > 1) and (DCREPLACE = lru) then vl.write := '1'; end if;

            end if;

          else                  -- write access

            if LOCAL_RAM and (lramen = '1') then

              lramwr := '1'; lramrd := '1';

              if (dci.size = "11") then v.dstate := "100"; end if; -- double store

            elsif (r.stpend  = '0') or ((mcdo.ready and not r.req)= '1') then    -- wait for store queue

              v.req := '1'; v.stpend := '1';

              v.burst := dci.size(1) and dci.size(0);

              if (dci.size = "11") then v.dstate := "100"; end if; -- double store

            else                -- wait for store queue

              v.dstate := "110"; v.holdn := '0';

            end if;

            if (mcdo.dcs(0) = '1') and ((hit and (dci.size(1) or validraw)) = '1')

            then  -- write hit

              twrite := '1'; dwrite := '1';

              if (DSETS > 1) and (DCREPLACE = lru) then vl.write := '1'; end if;

              setrepl := std_logic_vector(conv_unsigned(set, SETBITS));

            end if;

            if (dci.size = "11") then v.xaddress(2) := '1'; end if;

          end if;

          if (DSETS > 1) then

            vl.set := std_logic_vector(conv_unsigned(set, SETBITS));

            v.setrepl := std_logic_vector(conv_unsigned(set, SETBITS));

            if ((not hit) and (not r.flush)) = '1' then

              case DCREPLACE is

              when rnd =>

                if DCLOCK_BIT = 1 then

                  if lock(conv_integer(r.rndcnt)) = '0' then v.setrepl := r.rndcnt;

                  else

                    v.setrepl := std_logic_vector(conv_unsigned(DSETS-1, SETBITS));

                    for i in DSETS-1 downto 0 loop