If a device has configurable bus-width, we need a stable way of
enumerating registers. The byte offset stays unchanged.
This change also makes it possible to put an arbitrary number of RegFields
starting at some address which are then chopped up into appropriately bus-
sized registers.
Running rocket-chip through the chisel3 gsdt branch which supports stricter connection checks and uses implicit definitions to deal with "old" direction overrides, exposed a possible bug in the Scala compiler.
[error] .../src/main/scala/uncore/devices/Prci.scala:27: value asOutput is not a member of uncore.devices.PRCIInterrupts{val mtip: chisel3.core.Bool; val msip: chisel3.core.Bool}
[error] possible cause: maybe a semicolon is missing before `value asOutput'?
[error] }.asOutput
[error] ^
[error] one error found
[error] (uncore/compile:compileIncremental) Compilation failed
This change isn't strictly required for current chisel3 code, but is being submitted in anticipation of an eventual merge of the gsdt branch prior to a compiler fix.