Subversion Repositories axi4_tlm_bfm

/*

        This file is part of the AXI4 Transactor and Bus Functional Model

        (axi4_tlm_bfm) project:

                http://www.opencores.org/project,axi4_tlm_bfm

        Description

        Implementation of AXI4 Master BFM core according to AXI4 protocol

        specification document.

        To Do: Implement AXI4-Lite and full AXI4 protocols.

        Author(s):

        - Daniel C.K. Kho, daniel.kho@opencores.org | daniel.kho@tauhop.com

        Copyright (C) 2012-2013 Authors and OPENCORES.ORG

        This source file may be used and distributed without

        restriction provided that this copyright statement is not

        removed from the file and that any derivative work contains

        the original copyright notice and the associated disclaimer.

        This source file 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 2.1 of the License, or (at your option) any

        later version.

        This source 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 Lesser General Public License for more

        details.

        You should have received a copy of the GNU Lesser General

        Public License along with this source; if not, download it

        from http://www.opencores.org/lgpl.shtml.

*/

library ieee; use ieee.std_logic_1164.all, ieee.numeric_std.all;

--library tauhop; use tauhop.axiTransactor.all;

--/* TODO remove once generic packages are supported. */

library tauhop; use tauhop.tlm.all, tauhop.axiTLM.all;

entity axiBfmMaster is

        port(aclk,n_areset:in std_ulogic;

                /* BFM signalling. */

                readRequest,writeRequest:in t_bfm:=((others=>'X'),(others=>'X'),false);

                readResponse,writeResponse:buffer t_bfm;                                                                        -- use buffer until synthesis tools support reading from out ports.

                /* AXI Master interface */

                axiMaster_in:in t_axi4StreamTransactor_s2m;

                axiMaster_out:buffer t_axi4StreamTransactor_m2s;

--              /* AXI Slave interface */

--              axiSlave_in:in tAxi4Transactor_m2s;

--              axiSlave_out:buffer tAxi4Transactor_s2m;

                symbolsPerTransfer:in t_cnt;

                outstandingTransactions:buffer t_cnt;

                /* Debug ports. */

--              dbg_cnt:out unsigned(9 downto 0);

--              dbg_axiRxFsm:out axiBfmStatesRx:=idle;

                dbg_axiTxFsm:out axiBfmStatesTx:=idle

        );

end entity axiBfmMaster;

architecture rtl of axiBfmMaster is

        /* Finite-state Machines. */

        signal axiTxState,next_axiTxState:axiBfmStatesTx:=idle;

        /* BFM signalling. */

        signal i_readRequest:t_bfm:=((others=>'0'),(others=>'0'),false);

        signal i_writeRequest:t_bfm:=((others=>'0'),(others=>'0'),false);

        signal i_readResponse,i_writeResponse:t_bfm;

begin

        /* Transaction counter. */

        process(n_areset,symbolsPerTransfer,aclk) is begin

                /* Using synchronous reset will meet timing. However, because outstandingTransactions is a huge

                        register set, using asynchronous reset will violate timing.

                        FIXME Try and close timing even with asynchronous reset applied on outstandingTransactions.

                                Using asynchronous reset will help to lower power.

                */

                if not n_areset then outstandingTransactions<=symbolsPerTransfer;

                elsif falling_edge(aclk) then

                        if outstandingTransactions<1 then

                                outstandingTransactions<=symbolsPerTransfer;

                                report "No more pending transactions." severity note;

                        elsif axiMaster_in.tReady then outstandingTransactions<=outstandingTransactions-1;

                        end if;

                end if;

        end process;

        /* next-state logic for AXI4-Stream Master Tx BFM. */

        axi_bfmTx_ns: process(all) is begin

                axiTxState<=next_axiTxState;

                if not n_areset then axiTxState<=idle;

                else

                        case next_axiTxState is

                                when idle=>

                                        if writeRequest.trigger xor i_writeRequest.trigger then axiTxState<=payload; end if;

                                when payload=>

                                        if outstandingTransactions<1 then axiTxState<=endOfTx; end if;

                                when endOfTx=>

                                        axiTxState<=idle;

                                when others=>axiTxState<=idle;

                        end case;

                end if;

        end process axi_bfmTx_ns;

        /* output logic for AXI4-Stream Master Tx BFM. */

        axi_bfmTx_op: process(all) is begin

                i_writeResponse<=writeResponse;

                axiMaster_out.tValid<=false;

                axiMaster_out.tLast<=false;

                axiMaster_out.tData<=(others=>'Z');

                i_writeResponse.trigger<=false;

                if writeRequest.trigger xor i_writeRequest.trigger then

                        axiMaster_out.tData<=writeRequest.message;

                        axiMaster_out.tValid<=true;

                end if;

                case next_axiTxState is

                        when payload=>

                                axiMaster_out.tData<=writeRequest.message;

                                axiMaster_out.tValid<=true;

                                if axiMaster_in.tReady then

                                        i_writeResponse.trigger<=true;

                                end if;

                                /* TODO change to a flag at user.vhdl. Move outstandingTransactions to user.vhdl. */

                                if outstandingTransactions<1 then axiMaster_out.tLast<=true; end if;

                        when others=> null;

                end case;

        end process axi_bfmTx_op;

        /* state registers and pipelines for AXI4-Stream Tx BFM. */

        process(n_areset,aclk) is begin

                if falling_edge(aclk) then

                        next_axiTxState<=axiTxState;

                        i_writeRequest<=writeRequest;

                end if;

        end process;

        process(aclk) is begin

                if rising_edge(aclk) then

                        writeResponse<=i_writeResponse;

                end if;

        end process;

        dbg_axiTxFSM<=axiTxState;

end architecture rtl;