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

--  Entity:         SPI_OC

--  File:           spi_oc.vhd

--  Author:         Thomas Ameseder, Gleichmann Electronics

--

--  Description:    VHDL wrapper for the Opencores SPI core with APB

--                  interface

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

--  CVS Entries:

--  $Date: 2006/12/04 14:44:05 $

--  $Author: tame $

--  $Log: spi_oc.vhd,v $

--  Revision 1.3  2006/12/04 14:44:05  tame

--  Changed interrupt output to LEON from a level (that is active until it is reset) to

--  a short pulse.

--

--  Revision 1.1  2006/11/17 12:28:56  tame

--  Added SPI files: Simple SPI package and a wrapper for the (modified)

--  OpenCores Simple SPI Core with APB interface.

--

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

library ieee;

use ieee.std_logic_1164.all;

library grlib;

use grlib.amba.all;

use grlib.stdlib.all;

use grlib.devices.all;

library opencores;

use opencores.occomp.all;

library gleichmann;

use gleichmann.sspi.all;

--  pragma translate_off

use std.textio.all;

--  pragma translate_on

entity spi_oc is

  generic (

    pindex : integer := 0;              -- Leon-Index

    paddr  : integer := 0;              -- Leon-Address

    pmask  : integer := 16#FFF#;        -- Leon-Mask

    pirq   : integer := 0               -- Leon-IRQ

    );

  port (

    rstn    : in  std_ulogic;           -- global Reset, active low

    clk     : in  std_ulogic;           -- global Clock

    apbi    : in  apb_slv_in_type;      -- APB-Input

    apbo    : out apb_slv_out_type;     -- APB-Output

    spi_in  : in  sspi_in_type;          -- MultIO-Inputs

    spi_out : out sspi_out_type          -- Spi-Outputs

    );

end entity spi_oc;

architecture implementation of spi_oc is

  constant data_width    : integer := 8;

  constant address_width : integer := 3;

  constant REVISION      : integer := 0;

  constant pconfig : apb_config_type := (

    1 => apb_iobar(paddr, pmask)

    );

  signal irq       : std_ulogic;

  signal irq_1t    : std_ulogic;

  signal irq_adapt : std_ulogic;        -- registered and converted to rising edge activity

begin

  simple_spi_top_1 : simple_spi_top

    port map (

      prdata_o  => apbo.prdata(data_width-1 downto 0),

      pirq_o    => irq,

      sck_o     => spi_out.sck,

      mosi_o    => spi_out.mosi,

      ssn_o     => spi_out.ssn,

      pclk_i    => clk,

      prst_i    => rstn,

      psel_i    => apbi.psel(pindex),

      penable_i => apbi.penable,

      paddr_i   => apbi.paddr(address_width+1 downto 2),  -- 32-bit addresses

      pwrite_i  => apbi.pwrite,

      pwdata_i  => apbi.pwdata(data_width-1 downto 0),

      miso_i    => spi_in.miso);

  -- drive selected interrupt, remaining bits with zeroes

  apbo.pirq(NAHBIRQ-1 downto pirq+1) <= (others => '0');

  -- apbo.pirq(pirq)                    <= irq;  -- corrected by MH, 28.11.2006

  apbo.pirq(pirq)                    <= irq_adapt;

  apbo.pirq(pirq-1 downto 0)         <= (others => '0');

  -- drive unused data bits with don't cares

  apbo.prdata(31 downto data_width) <= (others => '0');

  -- drive index for diagnostic use

  apbo.pindex                       <= pindex;

  -- drive slave configuration

  apbo.pconfig                      <= pconfig;

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

  -- Synchronous process to convert the high level interrupt from the core to

  -- to an rising edge triggered interrupt to be suitable for the Leon IRQCTL

  --    asynchronous low active reset like the open core simple SPI module !!!

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

  irq_adaption: process (clk, rstn)  -- added by MH, 28.11.2006

  begin  -- process irq_adaption)

    if rstn = '0' then

      irq_adapt <= '0';

      irq_1t    <= '0';

    elsif clk'event and clk = '1' then

      irq_1t    <= irq;

      irq_adapt <= irq and not irq_1t;

    end if;

  end process irq_adaption;

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

  -- DEBUG SECTION

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

--  pragma translate_off

  assert (pirq < 15 and pirq > 0 ) report

    "Simple SPI Controller interrupt warning: " &

    "0 does not exist, 15 is unmaskable, 16 to 31 are unused"

    severity warning;

  bootmsg : report_version

    generic map ("SPI_OC: Simple SPI Controller rev " & tost(REVISION) &

                 ", IRQ " & tost(pirq) &

                 ", APB slave " & tost(pindex));

--  pragma translate_on

end architecture implementation;