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rocket-chip/src/main/scala/rocketchip/DebugTransport.scala

93 lines
2.7 KiB
Scala

package rocketchip
import Chisel._
import uncore.devices.{DebugBusIO, AsyncDebugBusCrossing, DebugBusReq, DebugBusResp, DMKey}
import junctions._
import util._
import cde.{Parameters, Field}
case object IncludeJtagDTM extends Field[Boolean]
/* JTAG-based Debug Transport Module
* and synchronization logic.
*
* This implements JTAG interface described
* in the RISC-V Debug Specification
*
* This Module is currently a
* wrapper around a JTAG implementation
* of the Debug Transport Module.
* This is black-boxed because
* Chisel doesn't currently support:
* - Negative Edge Clocking
* - Asynchronous Resets
* (The tristate requirements of JTAG are exported from the
* Chisel domain with the DRV_TDO signal).
*
* The 'TRST' input is used to asynchronously
* reset the Debug Transport Module and the
* DTM side of the synchronizer.
* This design requires that TRST be
* synchronized to TCK (for de-assert) outside
* of this module. Your top level code should ensure
* that TRST is asserted before the rocket-chip core
* comes out of reset.
* Note that TRST is an optional
* part of the JTAG protocol, but it is not
* optional for interfacing with this logic.
*
*/
class JtagDTMWithSync(depth: Int = 1, sync: Int = 3)(implicit val p: Parameters)
extends Module {
// io.DebugBusIO <-> Sync <-> DebugBusIO <-> UInt <-> DTM Black Box
val io = new Bundle {
val jtag = new JTAGIO(true).flip()
val debug = new DebugBusIO()(p)
}
val req_width = io.debug.req.bits.getWidth
val resp_width = io.debug.resp.bits.getWidth
val jtag_dtm = Module (new DebugTransportModuleJtag(req_width, resp_width))
jtag_dtm.io.jtag <> io.jtag
val dtm_req = Wire(new DecoupledIO(UInt(width = req_width)))
val dtm_resp = Wire(new DecoupledIO(UInt(width = resp_width)))
val io_debug_bus = Wire (new DebugBusIO)
io.debug <> AsyncDebugBusCrossing(io.jtag.TCK, io.jtag.TRST, io_debug_bus, clock, reset, depth, sync)
// Translate from straight 'bits' interface of the blackboxes
// into the Resp/Req data structures.
io_debug_bus.req.valid := dtm_req.valid
io_debug_bus.req.bits := new DebugBusReq(p(DMKey).nDebugBusAddrSize).fromBits(dtm_req.bits)
dtm_req.ready := io_debug_bus.req.ready
dtm_resp.valid := io_debug_bus.resp.valid
dtm_resp.bits := io_debug_bus.resp.bits.asUInt
io_debug_bus.resp.ready := dtm_resp.ready
dtm_req <> jtag_dtm.io.dtm_req
jtag_dtm.io.dtm_resp <> dtm_resp
}
class DebugTransportModuleJtag(reqSize : Int, respSize : Int)(implicit val p: Parameters) extends BlackBox {
val io = new Bundle {
val jtag = new JTAGIO(true).flip()
val dtm_req = new DecoupledIO(UInt(width = reqSize))
val dtm_resp = new DecoupledIO(UInt(width = respSize)).flip()
}
}