The MMU-500 supports the following TBU interfaces:
The MMU-500 uses the ACE-Lite interfaces to receive and forward transactions after a translation.
An AXI3 or AXI4 bus can be connected to this interface with certain limitations as described in AXI3 and AXI4 support.
When an ACE-Lite interface is used, the MMU-500 generates barrier transactions and updates attributes of input barrier transactions. Barrier transactions guarantee the ordering and observation of transactions in a system.
For more information on barrier transactions, see the ARM® AMBA® AXI and ACE Protocol Specification AXI3, AXI4, and AXI4-Lite ACE and ACE-Lite.
The MMU-500 supports only the ACE-Lite slave interface for every TBU. To connect to an AXI3 or AXI4 interface, you must:
Tie the extra ACE-Lite signals to their inactive values.
Tie the sysbardisable_<tbuname> signal HIGH.
The ACE-Lite slave interface, with _s suffix, drives the untranslated address to the TBU. You must connect pin-to-pin the read address, write address, read data, write data, and buffered write response channels of the ACE-Lite slave interface to an ACE-Lite master interface. In a system, the master interface can be the AXI bus infrastructure output or the output of a bridge that converts another bus protocol to AXI.
The MMU-500 supports only the ACE-Lite master interface for every TBU. You must tie the extra ACE-Lite signals to their inactive values and the sysbardisable_<tbuname> signal to HIGH to use AXI3 or AXI4 master interfaces.
The ACE-Lite master interface, with _m suffix, drives the translated address to the downstream slave. You must connect pin-to-pin the read address, write address, read data, write data, and buffered write response channels to the corresponding ACE-Lite slave interface.
If the MMU-500 is configured to support a dedicated interface for PTWs, you must connect the read address and read data channels of the slave interface associated with the PTWs to the MMU-500 PTW channel. In this configuration, the PTW channel contains the _ptw suffix. For example, araddr_ptw and acaddr_ptw.
The TBU in the MMU-500 receives, passes on, and generates barriers of its own.
The MMU-500 generates a DSBSYS barrier on its own, after ensuring that all invalidation-related transactions are initiated when sysbardisable_<tbuname> is LOW, and on receiving one of the following:
The SYNC message received on the programming interface.
The DVM SYNC message.
For more information on SYNC and DVM SYNC messages, see the ARM® AMBA® AXI and ACE Protocol Specification AXI3, AXI4, and AXI4-Lite ACE and ACE-Lite.
The sideband interface provides associated information, such as data byte, transfer, packet, or frame-based information along with the ACE-Lite interface. See Sideband signals.
The StreamID and security state determination are associated with the ACE-Lite slave interface to each TBU.
The StreamID interface is a sideband interface for the MMU-500 TBU slave interface. It provides additional information about the source of the incoming transaction. This information is used to map the transaction to a particular context for translation.
The MMU-500 samples signals in the interface along with each valid address transaction.
The SSD interface is a sideband interface for the MMU-500 TBU slave interface. It provides information about the security state of a transaction.
The MMU-500 samples signals in this interface along with each valid address transaction, in a similar manner to the StreamID.