How to export my custom IO signals at RocketTile module to DigitalTop's IO?

[csgxiong]

Background Work

• Yes, I searched the mailing list
• Yes, I searched the documentation

Feature Description

I have some custom IO signals (Both input and output ) at RocketTile module.And I want to export them to DigitalTop's IO.

Motivating Example

I have some custom IO signals (Both input and output ) at RocketTile module.And I want to export them to DigitalTop's IO.
When I try to add codes below, it will cause some errors.
Code:
class ChipyardSubsystemModuleImp[+L <: ChipyardSubsystem](_outer: L) extends BaseSubsystemModuleImp(_outer)
with HasTilesModuleImp
{
// Generate C header with relevant information for Dromajo
// This is included in the dromajo_params.h header file
DromajoHelper.addArtefacts(InSubsystem)
val io = IO(new Bundle{
val clk_en = Output(Bool())
})
io.clk_en := outer.tiles(0).module.roccPort.clk_en
}
Error log :
Exception in thread "main" java.lang.reflect.InvocationTargetException
at ... ()
at freechips.rocketchip.stage.phases.PreElaboration.$anonfun$transform$1(PreElaboration.scala:36)
at ... ()
at ... (Stack trace trimmed to user code only. Rerun with --full-stacktrace to see the full stack trace)
Caused by: chisel3.internal.ChiselException: Connection between sink (DigitalTop.io.clk_en: IO[Bool]) and source (RocketTile.roccPort.clk_en: IO[Bool]) failed @: Sink or source unavailable to current module.
at chisel3.internal.throwException$.apply(Error.scala:169)
at chisel3.Data.connect(Data.scala:635)
at chisel3.Data.$anonfun$$colon$eq$1(Data.scala:796)
at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.scala:18)
at chisel3.internal.prefix$.apply(prefix.scala:31)
at chisel3.Data.$colon$eq(Data.scala:796)

So Does anyone have any ideas on this?
Thanks.
B.R.

[jerryz123]

You should create a new trait for DigitalTop named: CanHaveRocketTileCustomIO. Within this trait, you can filter the totalTiles list to get the RocketTile modules.

Within each RocketTile, you should create a BundleBridgeSource node as the "source" of your signal.
Within CanHaveRocketTileCustomIO, you can create a corresponding BundleBridgeSink for each RocketTile, and connect it to the matching RocketTile.

Then, in CanHaveRocketTileCustomIO, you'll have access to the bundle from the BundleBridgeSink. You can punch this signal out as a IO of DigitalTop

[csgxiong]

@jerryz123
Tank you, Jerry. What you have mentioned above is just like the way reset_vector / hart_id IO to be exported at HasTiles.scala.
I had tried this way.But errors happened as below:
ERROR: BundleBridge.scala:137 "can only be used with Outptut-Directed Bundles"

My custom IO signals Not only have Input Directed IO, but also have Output Directed IO.So it seems to find another way.
I am not very familiar with the Chipyard project.

Thanks.
B.R.