Datasheet

Datasheet, Volume 2 29

Introduction
§
RW-LB
Read/Write Lock Bypass : Similar to RWL, these bits can be read and written by software. HW
can make these bits "Read Only" using a separate configuration bit or other logic. However, RW-
LB is a special case where the locking is controlled by the lock-bypass capability that is
controlled by the lock-bypass enable bits. Each lock-bypass enable bit enables a set of config
request sources that can bypass the lock. The requests sourced from the corresponding bypass
enable bits will be lock-bypassed (that is, RW) while requests sourced from other sources are
under lock control (RO). The lock bit and bypass enable bit are generally defined with RWO
attributes. Sticky can be used with this attribute (RW-SWB). These bits are only reinitialized to
their default values after PWRGOOD. Note that the lock bits may not be sticky, and it is
important that they are written to after reset to ensure that software will not be able to change
their values after a reset.
RO-FW
Read Only Forced Write :These bits are read only from the perspective of the cores. However,
Pcode is able to write to these registers.
RWS-O
If a register is both sticky and "once" then the sticky value applies to both the register value and
the "once" characteristic. Only a PWRGOOD reset will reset both the value and the "once" so that
the register can be written to again.
RW-V
These bits may be modified by hardware. Software cannot expect the values to stay unchanged.
This is similar to "volatile" in software land.
RWS-L
If a register is both sticky and locked, then the sticky behavior only applies to the value. The
sticky behavior of the lock is determined by the register that controls the lock.
RV
Reserved: These bits are reserved for future expansion and their value must not be modified by
software. When writing these bits, software must preserve the value read. The bits are read-only
must return 0 when read.
Table 1-3. Register Attributes Definitions (Sheet 2 of 2)
Attr Description