dcache.vhd

sparc org, vhdl rtl code

----------------------------------------------------------------------------
--  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';