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2.9
Address Translation
Peripheral Architecture
Remote VLYNQ device(s) are memory mapped to the local (host) device’s address space when a link is
established (this is similar to any other on-chip peripherals). Enumerating the VLYNQ devices (single or
multiple) into a coherent memory map for accessing each device is part of the initialization sequence.
After the enumeration, the host (local) device can access the remote device address map using local
device addresses. The VLYNQ module in the host device manages the address translation of the local
address to the remote address. A remote VLYNQ device is mapped to the local device’s address via the
address map registers (TX address map, RX address map size n, RX address map offset n, where n = 1
to 4). The transmit side has a contiguous map; the size of the map is the same as the remote device map.
Figure 7
illustrates this mapping.
In the local device, the address of the VLYNQ remote memory map in the local configuration space is the
transmit address accessing remote devices over the serial interface. The address of the VLYNQ remote
memory map is programmed in the TX address map register (XAM). When the local device transmits, first
it strips off the transmit address offset in the local device memory map. Then, the local device sends the
data with an address offset from the transmit address.
VLYNQ allows each receive packet address to be translated into one of the four mapped regions. The size
and offset of each memory region must be aligned to 32-bit words. No restriction is placed on
programming the size or on the offset of each mapped region, as long as the total memory that is mapped
into these one to four regions is not more then 64 MBytes.
Note:
Care should be taken while programming the receive address map size register (RAMSn)
and the receive address map offset register (RAMOn) values. These registers should be
programmed with valid address locations and memory size to match the device
specifications. See the Memory Map Summary and the System Interconnect sections in your
device-specific data manual to identify the valid memory regions that can be accessed by an
off-chip peer device through the VLYNQ interface.
The transmitted address is used to determine which remote mapped region is being accessed at the
remote device. This is achieved by summing each memory size sequentially until the memory size is
larger than the transmitted address. The last memory size that is added is the targeted region. A memory
size and an offset specify the remote map. The remote map is programmed in the RX address map size
register (RAMSn) and in the RX address map offset register (RAMOn) in the remote device.
SPRUE36A – September 2007
VLYNQ Port
17
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