diff --git a/.circleci/config.yml b/.circleci/config.yml
index ab123661..b6556850 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -287,6 +287,11 @@ jobs:
         steps:
             - prepare-rtl:
                 project-key: "chipyard-spiflashread"
+    prepare-chipyard-mmios:
+        executor: main-env
+        steps:
+            - prepare-rtl:
+                project-key: "chipyard-mmios"
     chipyard-rocket-run-tests:
         executor: main-env
         steps:
@@ -531,6 +536,10 @@ workflows:
                     - install-riscv-toolchain
                     - install-verilator
 
+            - prepare-chipyard-mmios:
+                requires:
+                    - install-riscv-toolchain
+
             # Run the respective tests
 
             # Run the example tests
diff --git a/.circleci/defaults.sh b/.circleci/defaults.sh
index b9aeeb3b..7cb8c1e2 100755
--- a/.circleci/defaults.sh
+++ b/.circleci/defaults.sh
@@ -47,23 +47,25 @@ LOCAL_FIRESIM_DIR=$LOCAL_CHIPYARD_DIR/sims/firesim/sim
 
 # key value store to get the build strings
 declare -A mapping
-mapping["chipyard-rocket"]="SUB_PROJECT=chipyard"
-mapping["chipyard-sha3"]="SUB_PROJECT=chipyard CONFIG=Sha3RocketConfig"
-mapping["chipyard-streaming-fir"]="SUB_PROJECT=chipyard CONFIG=StreamingFIRRocketConfig"
-mapping["chipyard-streaming-passthrough"]="SUB_PROJECT=chipyard CONFIG=StreamingPassthroughRocketConfig"
-mapping["chipyard-hetero"]="SUB_PROJECT=chipyard CONFIG=LargeBoomAndRocketConfig"
-mapping["chipyard-boom"]="SUB_PROJECT=chipyard CONFIG=SmallBoomConfig"
-mapping["chipyard-blkdev"]="SUB_PROJECT=chipyard CONFIG=SimBlockDeviceRocketConfig"
-mapping["chipyard-hwacha"]="SUB_PROJECT=chipyard CONFIG=HwachaRocketConfig"
-mapping["chipyard-gemmini"]="SUB_PROJECT=chipyard CONFIG=GemminiRocketConfig"
-mapping["chipyard-ariane"]="SUB_PROJECT=chipyard CONFIG=ArianeConfig"
-mapping["chipyard-spiflashread"]="SUB_PROJECT=chipyard CONFIG=LargeSPIFlashROMRocketConfig"
-mapping["chipyard-spiflashwrite"]="SUB_PROJECT=chipyard CONFIG=SmallSPIFlashRocketConfig"
-mapping["tracegen"]="SUB_PROJECT=chipyard CONFIG=NonBlockingTraceGenL2Config TOP=TraceGenSystem"
-mapping["tracegen-boom"]="SUB_PROJECT=chipyard CONFIG=BoomTraceGenConfig TOP=TraceGenSystem"
-mapping["chipyard-nvdla"]="SUB_PROJECT=chipyard CONFIG=SmallNVDLARocketConfig"
+mapping["chipyard-rocket"]=""
+mapping["chipyard-sha3"]=" CONFIG=Sha3RocketConfig"
+mapping["chipyard-streaming-fir"]=" CONFIG=StreamingFIRRocketConfig"
+mapping["chipyard-streaming-passthrough"]=" CONFIG=StreamingPassthroughRocketConfig"
+mapping["chipyard-hetero"]=" CONFIG=LargeBoomAndRocketConfig"
+mapping["chipyard-boom"]=" CONFIG=SmallBoomConfig"
+mapping["chipyard-blkdev"]=" CONFIG=SimBlockDeviceRocketConfig"
+mapping["chipyard-hwacha"]=" CONFIG=HwachaRocketConfig"
+mapping["chipyard-gemmini"]=" CONFIG=GemminiRocketConfig"
+mapping["chipyard-ariane"]=" CONFIG=ArianeConfig"
+mapping["chipyard-spiflashread"]=" CONFIG=LargeSPIFlashROMRocketConfig"
+mapping["chipyard-spiflashwrite"]=" CONFIG=SmallSPIFlashRocketConfig"
+mapping["chipyard-mmios"]=" CONFIG=MMIORocketConfig verilog"
+mapping["tracegen"]=" CONFIG=NonBlockingTraceGenL2Config TOP=TraceGenSystem"
+mapping["tracegen-boom"]=" CONFIG=BoomTraceGenConfig TOP=TraceGenSystem"
+mapping["chipyard-nvdla"]=" CONFIG=SmallNVDLARocketConfig"
 mapping["firesim"]="SCALA_TEST=firesim.firesim.RocketNICF1Tests"
 mapping["firesim-multiclock"]="SCALA_TEST=firesim.firesim.RocketMulticlockF1Tests"
 mapping["fireboom"]="SCALA_TEST=firesim.firesim.BoomF1Tests"
 mapping["icenet"]="SUB_PROJECT=icenet"
 mapping["testchipip"]="SUB_PROJECT=testchipip"
+
diff --git a/generators/chipyard/src/main/scala/IOBinders.scala b/generators/chipyard/src/main/scala/IOBinders.scala
index 1a366d19..115723ab 100644
--- a/generators/chipyard/src/main/scala/IOBinders.scala
+++ b/generators/chipyard/src/main/scala/IOBinders.scala
@@ -5,11 +5,11 @@ import chisel3._
 import chisel3.experimental.{Analog, IO}
 
 import freechips.rocketchip.config.{Field, Config, Parameters}
-import freechips.rocketchip.diplomacy.{LazyModule}
+import freechips.rocketchip.diplomacy.{LazyModule, LazyModuleImpLike}
 import freechips.rocketchip.devices.debug._
 import freechips.rocketchip.subsystem._
 import freechips.rocketchip.system.{SimAXIMem}
-import freechips.rocketchip.amba.axi4.{AXI4Bundle, AXI4SlaveNode, AXI4EdgeParameters}
+import freechips.rocketchip.amba.axi4.{AXI4Bundle, AXI4SlaveNode, AXI4MasterNode, AXI4EdgeParameters}
 import freechips.rocketchip.util._
 import freechips.rocketchip.groundtest.{GroundTestSubsystemModuleImp, GroundTestSubsystem}
 
@@ -52,6 +52,21 @@ case object IOBinders extends Field[Map[String, (Any) => Seq[IOBinderTuple]]](
   Map[String, (Any) => Seq[IOBinderTuple]]().withDefaultValue((Any) => Nil)
 )
 
+// Note: The parameters instance is accessible only through LazyModule
+// or LazyModuleImpLike. The self-type requirement in traits like
+// CanHaveMasterAXI4MemPort is insufficient to make it accessible to the IOBinder
+// As a result, IOBinders only work on Modules which inherit LazyModule or
+// or LazyModuleImpLike
+object GetSystemParameters {
+  def apply(s: Any): Parameters = {
+    s match {
+      case s: LazyModule => s.p
+      case s: LazyModuleImpLike => s.p
+      case _ => throw new Exception(s"Trying to get Parameters from a system that is not LazyModule or LazyModuleImpLike")
+    }
+  }
+}
+
 // This macro overrides previous matches on some Top mixin. This is useful for
 // binders which drive IO, since those typically cannot be composed
 class OverrideIOBinder[T](fn: => (T) => Seq[IOBinderTuple])(implicit tag: ClassTag[T]) extends Config((site, here, up) => {
@@ -185,10 +200,19 @@ object AddIOCells {
     (port, ios)
   }
 
-  def axi4(io: Seq[AXI4Bundle], node: AXI4SlaveNode): Seq[(AXI4Bundle, AXI4EdgeParameters, Seq[IOCell])] = {
+  def axi4(io: Seq[AXI4Bundle], node: AXI4SlaveNode, name: String): Seq[(AXI4Bundle, AXI4EdgeParameters, Seq[IOCell])] = {
     io.zip(node.in).zipWithIndex.map{ case ((mem_axi4, (_, edge)), i) => {
-      val (port, ios) = IOCell.generateIOFromSignal(mem_axi4, Some(s"iocell_mem_axi4_${i}"))
-      port.suggestName(s"mem_axi4_${i}")
+      val (port, ios) = IOCell.generateIOFromSignal(mem_axi4, Some(s"iocell_${name}_axi4_slave_${i}"))
+      port.suggestName(s"${name}_axi4_slave_${i}")
+      (port, edge, ios)
+    }}
+  }
+  def axi4(io: Seq[AXI4Bundle], node: AXI4MasterNode, name: String): Seq[(AXI4Bundle, AXI4EdgeParameters, Seq[IOCell])] = {
+    io.zip(node.out).zipWithIndex.map{ case ((mem_axi4, (_, edge)), i) => {
+      //val (port, ios) = IOCell.generateIOFromSignal(mem_axi4, Some(s"iocell_${name}_axi4_master_${i}"))
+      val port = IO(Flipped(AXI4Bundle(edge.bundle)))
+      val ios = IOCell.generateFromSignal(mem_axi4, port, Some(s"iocell_${name}_axi4_master_${i}"))
+      port.suggestName(s"${name}_axi4_master_${i}")
       (port, edge, ios)
     }}
   }
@@ -256,22 +280,19 @@ class WithSimNIC extends OverrideIOBinder({
   (system: CanHavePeripheryIceNICModuleImp) => system.connectSimNetwork(system.clock, system.reset.asBool); Nil
 })
 
-// Note: The parameters instance is accessible only through the BaseSubsystem
-// or some parent class (IsAttachable, BareSubsystem -> LazyModule). The
-// self-type requirement in CanHaveMasterAXI4MemPort is insufficient to make it
-// accessible to the IOBinder
 // DOC include start: WithSimAXIMem
 class WithSimAXIMem extends OverrideIOBinder({
-  (system: CanHaveMasterAXI4MemPort with BaseSubsystem) => {
-    val peiTuples = AddIOCells.axi4(system.mem_axi4, system.memAXI4Node)
+  (system: CanHaveMasterAXI4MemPort) => {
+    implicit val p: Parameters = GetSystemParameters(system)
+    val peiTuples = AddIOCells.axi4(system.mem_axi4, system.memAXI4Node, "mem")
     // TODO: we are inlining the connectMem method of SimAXIMem because
     //   it takes in a dut rather than seq of axi4 ports
     val harnessFn = (th: chipyard.TestHarness) => {
       peiTuples.map { case (port, edge, ios) =>
-        val mem = LazyModule(new SimAXIMem(edge, size = system.p(ExtMem).get.master.size)(system.p))
+        val mem = LazyModule(new SimAXIMem(edge, size = p(ExtMem).get.master.size))
         Module(mem.module).suggestName("mem")
         mem.io_axi4.head <> port
-        }
+      }
       Nil
     }
     Seq((peiTuples.map(_._1), peiTuples.flatMap(_._3), Some(harnessFn)))
@@ -280,12 +301,13 @@ class WithSimAXIMem extends OverrideIOBinder({
 // DOC include end: WithSimAXIMem
 
 class WithBlackBoxSimMem extends OverrideIOBinder({
-  (system: CanHaveMasterAXI4MemPort with BaseSubsystem) => {
-    val peiTuples = AddIOCells.axi4(system.mem_axi4, system.memAXI4Node)
+  (system: CanHaveMasterAXI4MemPort) => {
+    implicit val p: Parameters = GetSystemParameters(system)
+    val peiTuples = AddIOCells.axi4(system.mem_axi4, system.memAXI4Node, "mem")
     val harnessFn = (th: chipyard.TestHarness) => {
       peiTuples.map { case (port, edge, ios) =>
-        val memSize = system.p(ExtMem).get.master.size
-        val lineSize = system.p(CacheBlockBytes)
+        val memSize = p(ExtMem).get.master.size
+        val lineSize = p(CacheBlockBytes)
         val mem = Module(new SimDRAM(memSize, lineSize, edge.bundle))
         mem.io.axi <> port
         mem.io.clock := th.clock
@@ -298,7 +320,19 @@ class WithBlackBoxSimMem extends OverrideIOBinder({
 })
 
 class WithSimAXIMMIO extends OverrideIOBinder({
-  (system: CanHaveMasterAXI4MMIOPort with BaseSubsystem) => SimAXIMem.connectMMIO(system)(system.p); Nil
+  (system: CanHaveMasterAXI4MMIOPort) => {
+    implicit val p: Parameters = GetSystemParameters(system)
+    val peiTuples = AddIOCells.axi4(system.mmio_axi4, system.mmioAXI4Node, "mmio_mem")
+    val harnessFn = (th: chipyard.TestHarness) => {
+      peiTuples.zipWithIndex.map { case ((port, edge, ios), i) =>
+        val mmio_mem = LazyModule(new SimAXIMem(edge, size = 4096))
+        Module(mmio_mem.module).suggestName(s"mmio_mem_${i}")
+        mmio_mem.io_axi4.head <> port
+      }
+      Nil
+    }
+    Seq((peiTuples.map(_._1), peiTuples.flatMap(_._3), Some(harnessFn)))
+  }
 })
 
 class WithDontTouchPorts extends OverrideIOBinder({
@@ -315,21 +349,16 @@ class WithTieOffInterrupts extends OverrideIOBinder({
 })
 
 class WithTieOffL2FBusAXI extends OverrideIOBinder({
-  (system: CanHaveSlaveAXI4Port with BaseSubsystem) => {
-    system.l2_frontend_bus_axi4.foreach(axi => {
-      axi.tieoff()
-      experimental.DataMirror.directionOf(axi.ar.ready) match {
-        case ActualDirection.Input =>
-          axi.r.bits := DontCare
-          axi.b.bits := DontCare
-        case ActualDirection.Output =>
-          axi.aw.bits := DontCare
-          axi.ar.bits := DontCare
-          axi.w.bits := DontCare
-        case _ => throw new Exception("Unknown AXI port direction")
+  (system: CanHaveSlaveAXI4Port) => {
+    val peiTuples = AddIOCells.axi4(system.l2_frontend_bus_axi4, system.l2FrontendAXI4Node, "l2_fbus")
+    val harnessFn = (th: chipyard.TestHarness) => {
+      peiTuples.zipWithIndex.map { case ((port, edge, ios), i) =>
+        port := DontCare // tieoff doesn't completely tie-off, for some reason
+        port.tieoff()
       }
-    })
-    Nil
+      Nil
+    }
+    Seq((peiTuples.map(_._1), peiTuples.flatMap(_._3), Some(harnessFn)))
   }
 })
 
diff --git a/generators/chipyard/src/main/scala/config/RocketConfigs.scala b/generators/chipyard/src/main/scala/config/RocketConfigs.scala
index 06257c7b..3dc7d22d 100644
--- a/generators/chipyard/src/main/scala/config/RocketConfigs.scala
+++ b/generators/chipyard/src/main/scala/config/RocketConfigs.scala
@@ -542,3 +542,21 @@ class LargeNVDLARocketConfig extends Config(
   new freechips.rocketchip.subsystem.WithNBigCores(1) ++
   new freechips.rocketchip.subsystem.WithCoherentBusTopology ++
   new freechips.rocketchip.system.BaseConfig)
+
+class MMIORocketConfig extends Config(
+  new chipyard.iobinders.WithUARTAdapter ++
+  new chipyard.iobinders.WithTieOffInterrupts ++
+  new chipyard.iobinders.WithBlackBoxSimMem ++
+  new chipyard.iobinders.WithTiedOffDebug ++
+  new chipyard.iobinders.WithSimSerial ++
+  new chipyard.iobinders.WithTieOffL2FBusAXI ++ // Tie-off the incoming MMIO port
+  new chipyard.iobinders.WithSimAXIMMIO ++ // Attach a simulated memory to the outwards MMIO port
+  new testchipip.WithTSI ++
+  new chipyard.config.WithBootROM ++
+  new chipyard.config.WithUART ++
+  new chipyard.config.WithL2TLBs(1024) ++
+  new freechips.rocketchip.subsystem.WithInclusiveCache ++
+  new freechips.rocketchip.subsystem.WithNExtTopInterrupts(0) ++
+  new freechips.rocketchip.subsystem.WithNBigCores(1) ++
+  new freechips.rocketchip.subsystem.WithCoherentBusTopology ++
+  new freechips.rocketchip.system.BaseConfig)
diff --git a/generators/firechip/src/main/scala/BridgeBinders.scala b/generators/firechip/src/main/scala/BridgeBinders.scala
index eeb19559..eba57451 100644
--- a/generators/firechip/src/main/scala/BridgeBinders.scala
+++ b/generators/firechip/src/main/scala/BridgeBinders.scala
@@ -26,7 +26,7 @@ import ariane.ArianeTile
 
 import boom.common.{BoomTile}
 
-import chipyard.iobinders.{IOBinders, OverrideIOBinder, ComposeIOBinder}
+import chipyard.iobinders.{IOBinders, OverrideIOBinder, ComposeIOBinder, GetSystemParameters}
 import testchipip.{CanHaveTraceIOModuleImp}
 
 object MainMemoryConsts {
@@ -56,17 +56,20 @@ class WithBlockDeviceBridge extends OverrideIOBinder({
 
 
 class WithFASEDBridge extends OverrideIOBinder({
-  (system: CanHaveMasterAXI4MemPort with BaseSubsystem) => {
-    implicit val p = system.p
+  (system: CanHaveMasterAXI4MemPort) => {
+    implicit val p: Parameters = GetSystemParameters(system)
     (system.mem_axi4 zip system.memAXI4Node.in).foreach({ case (axi4, (_, edge)) =>
       val nastiKey = NastiParameters(axi4.r.bits.data.getWidth,
                                      axi4.ar.bits.addr.getWidth,
                                      axi4.ar.bits.id.getWidth)
-      FASEDBridge(system.module.clock, axi4, system.module.reset.toBool,
-        CompleteConfig(p(firesim.configs.MemModelKey),
-                       nastiKey,
-                       Some(AXI4EdgeSummary(edge)),
-                       Some(MainMemoryConsts.globalName)))
+      system match {
+        case s: BaseSubsystem => FASEDBridge(s.module.clock, axi4, s.module.reset.toBool,
+          CompleteConfig(p(firesim.configs.MemModelKey),
+                         nastiKey,
+                         Some(AXI4EdgeSummary(edge)),
+                         Some(MainMemoryConsts.globalName)))
+        case _ => throw new Exception("Attempting to attach FASED Bridge to misconfigured design")
+      }
     })
     Nil
   }
diff --git a/tools/barstools b/tools/barstools
index 7e6e19b8..aa1c90c4 160000
--- a/tools/barstools
+++ b/tools/barstools
@@ -1 +1 @@
-Subproject commit 7e6e19b8adf3b625b31b09173ecae5f634c83e1b
+Subproject commit aa1c90c4ccb73c2c379550f3296892cc81e8a195