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:      ahbctrl

-- File:        ahbctrl.vhd

-- Author:      Jiri Gaisler, Gaisler Research

-- Modified:    Edvin Catovic, Gaisler Research

-- Description: AMBA arbiter, decoder and multiplexer with plug&play support

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

library ieee;

use ieee.std_logic_1164.all;

library grlib;

use grlib.stdlib.all;

use grlib.amba.all;

-- pragma translate_off

use grlib.devices.all;

use std.textio.all;

-- pragma translate_on

entity ahbctrl is

  generic (

    defmast     : integer := 0;          -- default master

    split       : integer := 0;          -- split support

    rrobin      : integer := 0;          -- round-robin arbitration

    timeout     : integer range 0 to 255 := 0;  -- HREADY timeout

    ioaddr      : ahb_addr_type := 16#fff#;  -- I/O area MSB address

    iomask      : ahb_addr_type := 16#fff#;  -- I/O area address mask

    cfgaddr     : ahb_addr_type := 16#ff0#;  -- config area MSB address

    cfgmask     : ahb_addr_type := 16#ff0#;  -- config area address mask

    nahbm       : integer range 1 to NAHBMST := NAHBMST; -- number of masters

    nahbs       : integer range 1 to NAHBSLV := NAHBSLV; -- number of slaves

    ioen        : integer range 0 to 15 := 1;    -- enable I/O area

    disirq      : integer range 0 to 1 := 0;     -- disable interrupt routing

    fixbrst     : integer range 0 to 1 := 0;     -- support fix-length bursts

    debug       : integer range 0 to 2 := 2;     -- report cores to console

    fpnpen      : integer range 0 to 1 := 0; -- full PnP configuration decoding

    icheck      : integer range 0 to 1 := 1;

    devid       : integer := 0;               -- unique device ID

    enbusmon    : integer range 0 to 1 := 0; --enable bus monitor

    assertwarn  : integer range 0 to 1 := 0; --enable assertions for warnings 

    asserterr   : integer range 0 to 1 := 0; --enable assertions for errors

    hmstdisable : integer := 0; --disable master checks           

    hslvdisable : integer := 0; --disable slave checks

    arbdisable  : integer := 0; --disable arbiter checks

    mprio       : integer := 0; --master with highest priority

    enebterm    : integer range 0 to 1 := 0  --enable early burst termination

  );

  port (

    rst     : in  std_ulogic;

    clk     : in  std_ulogic;

    msti    : out ahb_mst_in_type;

    msto    : in  ahb_mst_out_vector;

    slvi    : out ahb_slv_in_type;

    slvo    : in  ahb_slv_out_vector;

    testen  : in  std_ulogic := '0';

    testrst : in  std_ulogic := '1';

    scanen  : in  std_ulogic := '0';

    testoen : in  std_ulogic := '1'

  );

end;

architecture rtl of ahbctrl is

constant nahbmx : integer := 2**log2(nahbm);

type nmstarr is array (1 to 3) of integer range 0 to nahbmx-1;

type nvalarr is array (1 to 3) of boolean;

type reg_type is record

  hmaster      : integer range 0 to nahbmx -1;

  hmasterd     : integer range 0 to nahbmx -1;

  hslave       : integer range 0 to nahbs-1;

  hmasterlock  : std_ulogic;

  hmasterlockd : std_ulogic;

  hready       : std_ulogic;

  defslv       : std_ulogic;

  htrans       : std_logic_vector(1 downto 0);

  haddr        : std_logic_vector(15 downto 2);

  cfgsel       : std_ulogic;

  cfga11       : std_ulogic;

  hrdatam      : std_logic_vector(31 downto 0);

  hrdatas      : std_logic_vector(31 downto 0);

  beat         : std_logic_vector(3 downto 0);

  defmst       : std_ulogic;

  ldefmst      : std_ulogic;

end record;

  constant primst : std_logic_vector(NAHBMST downto 0) := conv_std_logic_vector(mprio, NAHBMST+1);

  type l0_type is array (0 to 15) of std_logic_vector(2 downto 0);

  type l1_type is array (0 to 7) of std_logic_vector(3 downto 0);

  type l2_type is array (0 to 3) of std_logic_vector(4 downto 0);

  type l3_type is array (0 to 1) of std_logic_vector(5 downto 0);

  type tztab_type is array (0 to 15) of std_logic_vector(2 downto 0);

  --returns the index number of the highest priority request

  --signal in the two lsb bits when indexed with a 4-bit

  --request vector with the highest priority signal on the

  --lsb. the returned msb bit indicates if a request was

  --active ('1' = no request active corresponds to "0000")

  constant tztab : tztab_type := ("100", "000", "001", "000",

                                  "010", "000", "001", "000",

                                  "011", "000", "001", "000",

                                  "010", "000", "001", "000");

  --calculate the number of the highest priority request signal(up to 64

  --requests are supported) in vect_in using a divide and conquer

  --algorithm. The lower the index in the vector the higher the priority

  --of the signal. First 4-bit slices are indexed in tztab and the msb

  --indicates whether there is an active request or not. Then the resulting

  --3 bit vectors are compared in pairs (the one corresponding to (3:0) with

  --(7:4), (11:8) with (15:12) and so on). If the least significant of the two

  --contains an active signal a '0' is added to the msb side (the vector

  --becomes one bit wider at each level) to the next level to indicate that

  --there are active signals in the lower nibble of the two. Otherwise

  --the msb is removed from the vector corresponding to the higher nibble

  --and "10" is added if it does not contain active requests and "01" if

  --does contain active signals. Thus the msb still indicates if the new

  --slice contains active signals and a '1' is added if it is the higher

  --part. This results in a 6-bit vector containing the index number

  --of the highest priority master in 5:0 if bit 6 is '0' otherwise

  --no master requested the bus.

  function tz(vect_in : std_logic_vector) return std_logic_vector is

    variable vect : std_logic_vector(63 downto 0);

    variable l0 : l0_type;

    variable l1 : l1_type;

    variable l2 : l2_type;

    variable l3 : l3_type;

    variable l4 : std_logic_vector(6 downto 0);

    variable bci_lsb, bci_msb : std_logic_vector(3 downto 0);

    variable bco_lsb, bco_msb : std_logic_vector(2 downto 0);

    variable sel : std_logic;

  begin

    vect := (others => '1');

    vect(vect_in'length-1 downto 0) := vect_in;

    -- level 0

    for i in 0 to 7 loop

      bci_lsb := vect(8*i+3 downto 8*i);

      bci_msb := vect(8*i+7 downto 8*i+4);

      --lookup the highest priority request in each nibble

      bco_lsb := tztab(conv_integer(bci_lsb));

      bco_msb := tztab(conv_integer(bci_msb));

      --select which of two nibbles contain the highest priority ACTIVE

      --signal, and forward the corresponding vector to the next level

      sel := bco_lsb(2);

      if sel = '0' then l1(i) := '0' & bco_lsb;

      else l1(i) := bco_msb(2) & not bco_msb(2) & bco_msb(1 downto 0); end if;

    end loop;

    -- level 1

    for i in 0 to 3 loop

      sel := l1(2*i)(3);

      --select which of two 8-bit vectors contain the

      --highest priority ACTIVE signal. the msb set at the previous level

      --for each 8-bit slice determines this

      if sel = '0' then l2(i) := '0' & l1(2*i);

      else

        l2(i) := l1(2*i+1)(3) & not l1(2*i+1)(3) & l1(2*i+1)(2 downto 0);

      end if;

    end loop;

    -- level 2

    for i in 0 to 1 loop

      --16-bit vectors, the msb set at the previous level for each 16-bit

      --slice determines the higher priority slice

      sel := l2(2*i)(4);

      if sel = '0' then l3(i) := '0' & l2(2*i);

      else

        l3(i) := l2(2*i+1)(4) & not l2(2*i+1)(4) & l2(2*i+1)(3 downto 0);

      end if;

    end loop;

    --level 3

    --32-bit vectors, the msb set at the previous level for each 32-bit

    --slice determines the higher priority slice

    if l3(0)(5) = '0' then l4 := '0' & l3(0);

    else l4 := l3(1)(5) & not l3(1)(5) & l3(1)(4 downto 0); end if;

    return(l4);

  end;

  --invert the bit order of the hbusreq signals located in vect_in

  --since the highest hbusreq has the highest priority but the

  --algorithm in tz has the highest priority on lsb

  function lz(vect_in : std_logic_vector) return std_logic_vector is

    variable vect : std_logic_vector(vect_in'length-1 downto 0);

    variable vect2 : std_logic_vector(vect_in'length-1 downto 0);

  begin

    vect := vect_in;

    for i in vect'right to vect'left loop

      vect2(i) := vect(vect'left-i);

    end loop;

    return(tz(vect2));

  end;

-- Find next master:

--   * 2 arbitration policies: fixed priority or round-robin

--   * Fixed priority: priority is fixed, highest index has highest priority

--   * Round-robin: arbiter maintains circular queue of masters

--   * (master 0, master 1, ..., master (nahbmx-1)). First requesting master

--   * in the queue is granted access to the bus and moved to the end of the queue.  

--   * splitted masters are not granted

--   * bus is re-arbited when current owner does not request the bus,

--     or when it performs non-burst accesses

--   * fix length burst transfers will not be interrupted

--   * incremental bursts should assert hbusreq until last access

  procedure selmast(r      : in reg_type;

                  msto   : in ahb_mst_out_vector;

                  rsplit : in std_logic_vector(0 to nahbmx-1);

                  mast   : out integer range 0 to nahbmx-1;

                  defmst : out std_ulogic) is

  variable nmst    : nmstarr;

  variable nvalid  : nvalarr;

  variable rrvec : std_logic_vector(nahbmx*2-1 downto 0);

  variable zcnt  : std_logic_vector(log2(nahbmx)+1 downto 0);

  variable hpvec : std_logic_vector(nahbmx-1 downto 0);

  variable zcnt2 : std_logic_vector(log2(nahbmx) downto 0);

  begin

    nvalid(1 to 3) := (others => false); nmst(1 to 3) := (others => 0);

    mast := r.hmaster;

    defmst := '0';

    if nahbm = 1 then

      mast := 0;

    elsif rrobin = 0 then

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

      for i in 0 to nahbmx-1 loop

        --masters which have received split are not granted

        if ((rsplit(i) = '0') or (split = 0)) then

          hpvec(i) := msto(i).hbusreq;

        end if;

      end loop;

      --check if any bus requests are active (nvalid(2) set to true)

      --and determine the index (zcnt2) of the highest priority master

      zcnt2 := lz(hpvec)(log2(nahbmx) downto 0);

      if zcnt2(log2(nahbmx)) = '0' then nvalid(2) := true; end if;

      nmst(2) := conv_integer(not (zcnt2(log2(nahbmx)-1 downto 0)));

      --find the default master number

      for i in 0 to nahbmx-1 loop

        if not ((nmst(3) = defmast) and nvalid(3)) then

          nmst(3) := i; nvalid(3) := true;

        end if;

      end loop;

    else

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

      --mask requests up to and including current master. Concatenate

      --an unmasked request vector above the masked vector. Otherwise

      --the rules are the same as for fixed priority

      for i in 0 to nahbmx-1 loop

        if ((rsplit(i) = '0') or (split = 0)) then

          if (i <= r.hmaster) then rrvec(i) := '0';

          else rrvec(i) := msto(i).hbusreq; end if;

          rrvec(nahbmx+i) := msto(i).hbusreq;

        end if;

      end loop;

      --find the next master uzing tz which gives priority to lower

      --indexes

      zcnt := tz(rrvec)(log2(nahbmx)+1 downto 0);

      --was there a master requesting the bus?

      if zcnt(log2(nahbmx)+1) = '0' then nvalid(2) := true; end if;

      nmst(2) := conv_integer(zcnt(log2(nahbmx)-1 downto 0));

      --if no other master is requesting the bus select the current one

      nmst(3) := r.hmaster; nvalid(3) := true;

      --check if any masters configured with higher priority are requesting

      --the bus

      if mprio /= 0 then

        for i in 0 to nahbm-1 loop

          if (((rsplit(i) = '0') or (split = 0)) and (primst(i) = '1')) then

            if msto(i).hbusreq = '1' then nmst(1) := i; nvalid(1) := true; end if;

          end if;

        end loop;

      end if;

    end if;

    --select the next master. If for round robin a high priority master

    --(mprio) requested the bus if nvalid(1) is true. Otherwise

    --if nvalid(2) is true at least one master was requesting the bus

    --and the one with highest priority was selected. If none of these

    --were true then the default master is selected (nvalid(3) true)

    for i in 1 to 3 loop

      if nvalid(i) then mast := nmst(i); exit; end if;

    end loop;

    --if no master was requesting the bus and split is enabled

    --then select builtin dummy master which only does

    --idle transfers

    if (not (nvalid(1) or nvalid(2))) and (split /= 0) then

      defmst := orv(rsplit);

    end if;

  end;

  constant MIMAX : integer := log2x(nahbmx) - 1;

  constant SIMAX : integer := log2x(nahbs) - 1;

  constant IOAREA : std_logic_vector(11 downto 0) :=

        conv_std_logic_vector(ioaddr, 12);

  constant IOMSK  : std_logic_vector(11 downto 0) :=

        conv_std_logic_vector(iomask, 12);

  constant CFGAREA : std_logic_vector(11 downto 0) :=

        conv_std_logic_vector(cfgaddr, 12);

  constant CFGMSK  : std_logic_vector(11 downto 0) :=

        conv_std_logic_vector(cfgmask, 12);

  constant FULLPNP : boolean := (fpnpen /= 0);

  signal r, rin : reg_type;

  signal rsplit, rsplitin : std_logic_vector(0 to nahbmx-1);

-- pragma translate_off

  signal lmsti : ahb_mst_in_type;

  signal lslvi : ahb_slv_in_type;

-- pragma translate_on

begin

  comb : process(rst, msto, slvo, r, rsplit, testen, testrst, scanen, testoen)

  variable v : reg_type;

  variable nhmaster, hmaster : integer range 0 to nahbmx -1;

  variable hgrant  : std_logic_vector(0 to NAHBMST-1);   -- bus grant

  variable hsel    : std_logic_vector(0 to 31);   -- slave select

  variable hmbsel  : std_logic_vector(0 to NAHBAMR-1);

  variable nslave  : natural range 0 to 31;

  variable vsplit  : std_logic_vector(0 to nahbmx-1);

  variable bnslave : std_logic_vector(3 downto 0);

  variable area    : std_logic_vector(1 downto 0);

  variable hready  : std_ulogic;

  variable defslv  : std_ulogic;

  variable cfgsel  : std_ulogic;

  variable hcache  : std_ulogic;

  variable hresp   : std_logic_vector(1 downto 0);

  variable hrdata  : std_logic_vector(31 downto 0);

  variable haddr   : std_logic_vector(31 downto 0);

  variable hirq    : std_logic_vector(NAHBIRQ-1 downto 0);

  variable arb     : std_ulogic;

  variable hconfndx : integer range 0 to 7;

  variable vslvi   : ahb_slv_in_type;

  variable defmst   : std_ulogic;

  variable tmpv     : std_logic_vector(0 to nahbmx-1);

  begin

    v := r; hgrant := (others => '0'); defmst := '0';

    haddr := msto(r.hmaster).haddr;

    nhmaster := r.hmaster;

    --determine if bus should be rearbitrated. This is done if the current

    --master is not performing a locked transfer and if not in the middle

    --of burst

    arb := '0';

    if (r.hmasterlock or r.ldefmst) = '0' then

      case msto(r.hmaster).htrans is

        when HTRANS_IDLE => arb := '1';

        when HTRANS_NONSEQ =>

          case msto(r.hmaster).hburst is

            when HBURST_SINGLE => arb := '1';

            when HBURST_INCR => arb := not msto(r.hmaster).hbusreq;

            when others =>

          end case;

        when HTRANS_SEQ =>

          case msto(r.hmaster).hburst is

            when HBURST_WRAP4  | HBURST_INCR4  => if (fixbrst = 1) and (r.beat(1 downto 0) = "11")   then arb := '1'; end if;

            when HBURST_WRAP8  | HBURST_INCR8  => if (fixbrst = 1) and (r.beat(2 downto 0) = "111")  then arb := '1'; end if;

            when HBURST_WRAP16 | HBURST_INCR16 => if (fixbrst = 1) and (r.beat(3 downto 0) = "1111") then arb := '1'; end if;

            when HBURST_INCR => arb := not msto(r.hmaster).hbusreq;

            when others =>

          end case;

        when others => arb := '0';

      end case;

-- pragma translate_off 

      if enebterm = 1 then arb := '1'; end if;

-- pragma translate_on

    end if;

    if (split /= 0) then

      for i in 0 to nahbmx-1 loop

        tmpv(i) := (msto(i).htrans(1) or (msto(i).hbusreq)) and not rsplit(i) and not r.ldefmst;

      end loop;

      if (r.defmst and orv(tmpv))  = '1' then arb := '1'; end if;

    end if;

    --rearbitrate bus with selmast. If not arbitrated one must

    --ensure that the dummy master is selected for locked splits. 

    if (arb = '1') then

      selmast(r, msto, rsplit, nhmaster, defmst);

    elsif (split /= 0) then

      defmst := r.defmst;

    end if;

    -- slave decoding

    hsel := (others => '0'); hmbsel := (others => '0');

    for i in 0 to nahbs-1 loop

      for j in NAHBIR to NAHBCFG-1 loop

        area := slvo(i).hconfig(j)(1 downto 0);

        case area is

        when "10" =>

          if ((ioen = 0) or ((IOAREA and IOMSK) /= (haddr(31 downto 20) and IOMSK))) and

             ((slvo(i).hconfig(j)(31 downto 20) and slvo(i).hconfig(j)(15 downto 4)) =

              (haddr(31 downto 20) and slvo(i).hconfig(j)(15 downto 4))) and

              (slvo(i).hconfig(j)(15 downto 4) /= "000000000000")

          then hsel(i) := '1'; hmbsel(j-NAHBIR) := '1'; end if;

        when "11" =>

          if ((ioen /= 0) and ((IOAREA and IOMSK) = (haddr(31 downto 20) and IOMSK))) and

             ((slvo(i).hconfig(j)(31 downto 20) and slvo(i).hconfig(j)(15 downto 4)) =

              (haddr(19 downto  8) and slvo(i).hconfig(j)(15 downto 4))) and

              (slvo(i).hconfig(j)(15 downto 4) /= "000000000000")

          then hsel(i) := '1'; hmbsel(j-NAHBIR) := '1'; end if;

        when others =>

        end case;

      end loop;

    end loop;

    if r.defmst = '1' then hsel := (others => '0'); end if;

    bnslave(0) := hsel(1) or hsel(3) or hsel(5) or hsel(7) or

                  hsel(9) or hsel(11) or hsel(13) or hsel(15);

    bnslave(1) := hsel(2) or hsel(3) or hsel(6) or hsel(7) or

                  hsel(10) or hsel(11) or hsel(14) or hsel(15);

    bnslave(2) := hsel(4) or hsel(5) or hsel(6) or hsel(7) or

                  hsel(12) or hsel(13) or hsel(14) or hsel(15);

    bnslave(3) := hsel(8) or hsel(9) or hsel(10) or hsel(11) or

                  hsel(12) or hsel(13) or hsel(14) or hsel(15);

    nslave := conv_integer(bnslave(SIMAX downto 0));

    if ((((IOAREA and IOMSK) = (haddr(31 downto 20) and IOMSK)) and (ioen /= 0))

      or ((IOAREA = haddr(31 downto 20)) and (ioen = 0))) and

       ((CFGAREA and CFGMSK) = (haddr(19 downto  8) and CFGMSK))

       and (cfgmask /= 0)

    then cfgsel := '1'; hsel := (others => '0');

    else cfgsel := '0'; end if;

    if (nslave = 0) and (hsel(0) = '0') and (cfgsel = '0') then defslv := '1';

    else defslv := '0'; end if;

    if r.defmst = '1' then

      cfgsel := '0'; defslv := '1';

    end if;

-- error response on undecoded area

    v.hready := '0';

    hready := slvo(r.hslave).hready; hresp := slvo(r.hslave).hresp;

    if r.defslv = '1' then

      -- default slave

      if (r.htrans = HTRANS_IDLE) or (r.htrans = HTRANS_BUSY) then

        hresp := HRESP_OKAY; hready := '1';

      else

        -- return two-cycle error in case of unimplemented slave access

        hresp := HRESP_ERROR; hready := r.hready; v.hready := not r.hready;

      end if;

    end if;

    hrdata := slvo(r.hslave).hrdata;

    if cfgmask /= 0 then

--      v.hrdatam := msto(conv_integer(r.haddr(MIMAX+5 downto 5))).hconfig(conv_integer(r.haddr(4 downto 2)));

--      if r.haddr(11 downto MIMAX+6) /= zero32(11 downto MIMAX+6) then v.hrdatam := (others => '0'); end if;

--       if (r.haddr(10 downto MIMAX+6) = zero32(10 downto MIMAX+6)) and (r.haddr(4 downto 2) = "000")

      if FULLPNP then hconfndx := conv_integer(r.haddr(4 downto 2)); else hconfndx := 0; end if;

      if (r.haddr(10 downto MIMAX+6) = zero32(10 downto MIMAX+6)) and (FULLPNP or (r.haddr(4 downto 2) = "000"))

      then v.hrdatam := msto(conv_integer(r.haddr(MIMAX+5 downto 5))).hconfig(hconfndx);

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

--      v.hrdatas := slvo(conv_integer(r.haddr(SIMAX+5 downto 5))).hconfig(conv_integer(r.haddr(4 downto 2)));

--      if r.haddr(11 downto SIMAX+6) /= ('1' & zero32(10 downto SIMAX+6)) then v.hrdatas := (others => '0'); end if;

      --if (r.haddr(10 downto SIMAX+6) = zero32(10 downto SIMAX+6)) and

      if (r.haddr(10 downto SIMAX+6) = zero32(10 downto SIMAX+6)) and

        (FULLPNP or (r.haddr(4 downto 2) = "000") or (r.haddr(4) = '1'))

      then v.hrdatas := slvo(conv_integer(r.haddr(SIMAX+5 downto 5))).hconfig(conv_integer(r.haddr(4 downto 2)));

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

      if r.haddr(10 downto 4) = "1111111" then

         v.hrdatas(15 downto 0) := conv_std_logic_vector(LIBVHDL_BUILD, 16);

         v.hrdatas(31 downto 16) := conv_std_logic_vector(devid, 16);

      end if;

      if r.cfgsel = '1' then

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

        -- default slave

        if (r.htrans = HTRANS_IDLE) or (r.htrans = HTRANS_BUSY) then

          hresp := HRESP_OKAY; hready := '1';

        else

          -- return two-cycle read/write respons

          hresp := HRESP_OKAY; hready := r.hready; v.hready := not r.hready;

        end if;

        if r.cfga11 = '0' then hrdata := r.hrdatam;

        else hrdata := r.hrdatas; end if;

      end if;

    end if;

    --degrant all masters when split occurs for locked access

    if (r.hmasterlockd = '1') then

      if (hresp = HRESP_RETRY) or ((split /= 0) and (hresp = HRESP_SPLIT)) then

        nhmaster := r.hmaster;

      end if;

      if split /= 0 then

        if hresp = HRESP_SPLIT then

          v.ldefmst := '1'; defmst := '1';

        end if;

      end if;

    end if;

    if r.ldefmst = '1' then

      if orv(rsplit) = '0' then

        v.ldefmst := '0'; defmst := '0';

      end if;

    end if;

    if (split = 0) or (defmst = '0') then hgrant(nhmaster) := '1'; end if;