AEROFLEX GAISLER
43
RT-SPW-ROUTER
Copyright Aeroflex Gaisler AB
June 2012, Version 1.2
3.6
Configuration port
The configuration port uses the RMAP protocol (ECSS-E-ST-50-52C). Verified writes, reads and
read-modify-writes all of length 4 bytes are supported (8B for RMW if the mask field is included in
the count). Replies sent from the configuration port are always replied to the port they arrived from
regardless of the source address. The address space of the configuration port is specified in section
3.7. Addresses outside of the range will result in an authorization error. Table 32 gives a detailed list-
ing of the configuration port’s handling of RMAP packets.
Per default the configuration area can be accessed from all the ports. Configuration accesses can be
individually disabled per port using the CE bit in the port control register. Writes to the configuration
area can be globally disabled by writing a 0 to the WE bit in the configuration write enable register.
This disables write accesses from all ports to all registers except the configuration write enable regis-
ter itself.
There is also a signal which can be used to disable configuration accesses from all ports except port 1.
This signal overrides the settings of the CE bits in the port control registers. The global write enable
register still affects port 1 in this case.
When an otherwise correct RMAP command destined to the configuration port is received but not
allowed due to one or more of the configuration access disable options being enabled a reply with sta-
tus set to authorization failure will be sent if requested. If a reply is not requested the packet will be
silently discarded. In both cases the command will not be performed and has no effect on the configu-
ration port registers.
3.6.1
AMBA AHB slave interface
An AMBA AHB slave interface can be optionally included which makes the whole configuration port
memory area accessible from the AHB bus. The address offsets are the same as when accessing
through RMAP but the base address is different.
Only word accesses (32-bit) are allowed. The routing table is shared between the ports, RMAP target
and AHB slave so accesses from the AHB slave might be stalled because the of accesses from the
other sources. The priority order starting from the highest is router ports, RMAP target and AHB
slave. The router ports access order is controlled using a round-robin arbitration mechanism.
None of the registers and signals for limiting configuration accesses have any effect on the AHB slave
interface.
There is predetermined order in which error-codes are set in the case of multiple errors in the core. It
is shown in table 31.
Errors up to and including Invalid Data CRC (number 8) are checked before executing a command.
The other errors do not prevent verified operations from being performed.
The details of the support for the different commands are now presented. All defined commands
which are received but have an option set which is not supported in this specific implementation will
not be executed and a reply is sent (if the acknowledge bit was set) with error code 10.
