Subversion Repositories mips_enhanced

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

--  This file is a part of the GRLIB VHDL IP LIBRARY

--  Copyright (C) 2003, Gaisler Research

--

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

--  it under the terms of the GNU General Public License as published by

--  the Free Software Foundation; either version 2 of the License, 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 more details.

--

--  You should have received a copy of the GNU General Public License

--  along with this program; if not, write to the Free Software

--  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 

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

-- Entity:      mmutlbcam

-- File:        mmutlbcam.vhd

-- Author:      Konrad Eisele, Jiri Gaisler, Gaisler Research

-- Description: MMU TLB logic

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

library ieee;

use ieee.std_logic_1164.all;

library grlib;

use grlib.amba.all;

use grlib.stdlib.all;

library gaisler;

use gaisler.libiu.all;

use gaisler.libcache.all;

use gaisler.leon3.all;

use gaisler.mmuconfig.all;

use gaisler.mmuiface.all;

entity mmutlbcam is

  generic (

    tlb_type  : integer range 0 to 3 := 1

  );

  port (

      rst     : in std_logic;

      clk     : in std_logic;

      tlbcami : in mmutlbcam_in_type;

      tlbcamo : out mmutlbcam_out_type

  );

end mmutlbcam;

architecture rtl of mmutlbcam is

  constant M_TLB_FASTWRITE : integer range 0 to 3 := conv_integer(conv_std_logic_vector(tlb_type,2) and conv_std_logic_vector(2,2));   -- fast writebuffer

  type tlbcam_rtype is record

    btag     : tlbcam_reg;

  end record;

  signal r,c : tlbcam_rtype;

begin

  p0: process (rst, r, tlbcami)

  variable v : tlbcam_rtype;

  variable hm, hf                : std_logic;

  variable h_i1, h_i2, h_i3, h_c : std_logic;

  variable h_l2, h_l3            : std_logic;

  variable h_su_cnt              : std_logic;

  variable blvl                  : std_logic_vector(1 downto 0);

  variable bet                   : std_logic_vector(1 downto 0);

  variable bsu                   : std_logic;

  variable blvl_decode           : std_logic_vector(3 downto 0);

  variable bet_decode            : std_logic_vector(3 downto 0);

  variable ref, modified         : std_logic;

  variable tlbcamo_pteout        : std_logic_vector(31 downto 0);

  variable tlbcamo_LVL           : std_logic_vector(1 downto 0);

  variable tlbcamo_NEEDSYNC      : std_logic;

  variable tlbcamo_WBNEEDSYNC    : std_logic;

  begin

    v := r;

    --#init

    h_i1 := '0'; h_i2 := '0'; h_i3 := '0'; h_c := '0';

    hm := '0';

    hf := r.btag.VALID;

    blvl := r.btag.LVL;

    bet  := r.btag.ET;

    bsu  := r.btag.SU;

    bet_decode  := decode(bet);

    blvl_decode  := decode(blvl);

    ref := r.btag.R;

    modified := r.btag.M;

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

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

    -- prepare tag comparision

    if (r.btag.I1  = tlbcami.tagin.I1)  then h_i1 := '1';  else h_i1 := '0'; end if;

    if (r.btag.I2  = tlbcami.tagin.I2)  then h_i2 := '1';  else h_i2 := '0'; end if;

    if (r.btag.I3  = tlbcami.tagin.I3)  then h_i3 := '1';  else h_i3 := '0'; end if;

    if (r.btag.CTX = tlbcami.tagin.CTX) then h_c  := '1';  else h_c  := '0'; end if;

    -- #level 2 hit (segment)

    h_l2 := h_i1 and h_i2 ;

    -- #level 3 hit (page)

    h_l3 := h_i1 and h_i2 and h_i3;

    -- # context + su

    h_su_cnt := h_c or bsu;

    --# translation (match) op

    case blvl is

      when LVL_PAGE    => hm := h_l3 and h_c and r.btag.VALID;

      when LVL_SEGMENT => hm := h_l2 and h_c and r.btag.VALID;

      when LVL_REGION  => hm := h_i1 and h_c and r.btag.VALID;

      when LVL_CTX     => hm :=          h_c and r.btag.VALID;

      when others      => hm := 'X';

    end case;

    --# translation: update ref/mod bit

    tlbcamo_NEEDSYNC := '0';

    if (tlbcami.trans_op and hm  ) = '1' then

      v.btag.R := '1';

      v.btag.M := r.btag.M or tlbcami.tagin.M;

      tlbcamo_NEEDSYNC := (not r.btag.R) or (tlbcami.tagin.M and (not r.btag.M));  -- cam: ref/modified changed, write back synchronously

    end if;

    tlbcamo_WBNEEDSYNC := '0';

    if ( hm  ) = '1' then

      tlbcamo_WBNEEDSYNC := (not r.btag.R) or (tlbcami.tagin.M and (not r.btag.M));  -- cam: ref/modified changed, write back synchronously

    end if;

    --# flush operation

    -- tlbcam only stores PTEs, tlb does not store PTDs

    case tlbcami.tagin.TYP is

      when FPTY_PAGE =>                        -- page

        hf := hf and h_su_cnt and h_l3 and (blvl_decode(0));  -- only level 3 (page)

      when FPTY_SEGMENT =>                     -- segment

        hf := hf and h_su_cnt and h_l2 and (blvl_decode(0) or blvl_decode(1));  -- only level 2+3 (segment,page)

      when FPTY_REGION =>                      -- region

        hf := hf and h_su_cnt and h_i1 and (not blvl_decode(3));  -- only level 1+2+3 (region,segment,page)

      when FPTY_CTX =>                         -- context

        hf := hf and (h_c and (not bsu));

      when FPTY_N  =>                          -- entire

      when others =>

        hf := '0';

    end case;

    --# flush: invalidate on flush hit

    --if (tlbcami.flush_op and hf ) = '1' then

    if (tlbcami.flush_op  ) = '1' then

      v.btag.VALID := '0';

    end if;

    --# write op

    if ( tlbcami.write_op  = '1' ) then

      v.btag := tlbcami.tagwrite;

    end if;

    --# reset

    if (rst = '0' or tlbcami.mmuen = '0') then

      v.btag.VALID := '0';

    end if;

    tlbcamo_pteout(PTE_PPN_U downto PTE_PPN_D) := r.btag.PPN;

    tlbcamo_pteout(PTE_C) := r.btag.C;

    tlbcamo_pteout(PTE_M) := r.btag.M;

    tlbcamo_pteout(PTE_R) := r.btag.R;

    tlbcamo_pteout(PTE_ACC_U downto PTE_ACC_D) := r.btag.ACC;

    tlbcamo_pteout(PT_ET_U downto PT_ET_D) := r.btag.ET;

    tlbcamo_LVL(1 downto 0) := r.btag.LVL;

    --# drive signals

    tlbcamo.pteout   <= tlbcamo_pteout;

    tlbcamo.LVL      <= tlbcamo_LVL;

    --tlbcamo.hit      <= (tlbcami.trans_op and hm) or (tlbcami.flush_op and hf);

    tlbcamo.hit      <= (hm) or (tlbcami.flush_op and hf);

    tlbcamo.ctx      <= r.btag.CTX;       -- for diagnostic only

    tlbcamo.valid    <= r.btag.VALID;     -- for diagnostic only

    tlbcamo.vaddr    <= r.btag.I1 & r.btag.I2 & r.btag.I3 & "000000000000"; -- for diagnostic only

    tlbcamo.NEEDSYNC <= tlbcamo_NEEDSYNC;

    tlbcamo.WBNEEDSYNC <= tlbcamo_WBNEEDSYNC;

    c <= v;

  end process p0;

  p1: process (clk, c)

  begin if rising_edge(clk) then r <= c; end if;

  end process p1;

end rtl;