feat: implement privileged mode support

src/main/scala/interrupt/Clint.scala

@@ -0,0 +1,34 @@
+import chisel3._
+
+class Clint(p: CoreParams = CoreParams()) extends Module {
+  val io = IO(new Bundle {
+    val addr = Input(UInt(p.xlen.W))
+    val wen = Input(Bool())
+    val wdata = Input(UInt(p.xlen.W))
+    val ren = Input(Bool())
+    val rdata = Output(UInt(p.xlen.W))
+    val mipMSIP = Output(Bool())
+    val mipMTIP = Output(Bool())
+  })
+
+  val msip = RegInit(false.B)
+  val mtime = RegInit(0.U(p.xlen.W))
+  val mtimecmp = RegInit(~0.U(p.xlen.W))
+  mtime := mtime + 1.U
+
+  when(io.wen) {
+    when(io.addr === "h0".U) {
+      msip := io.wdata(0)
+    }.elsewhen(io.addr === "h4000".U) {
+      mtimecmp := io.wdata
+    }.elsewhen(io.addr === "hbff8".U) {
+      mtime := io.wdata
+    }
+  }
+
+  io.rdata := Mux(io.addr === "h0".U, msip,
+    Mux(io.addr === "h4000".U, mtimecmp,
+      Mux(io.addr === "hbff8".U, mtime, 0.U)))
+  io.mipMSIP := msip
+  io.mipMTIP := mtime >= mtimecmp
+}