From 739cf0763782ddc8fd7973082f9746ae977942e2 Mon Sep 17 00:00:00 2001
From: Andrew Waterman <waterman@cs.berkeley.edu>
Date: Wed, 27 Apr 2016 14:54:51 -0700
Subject: [PATCH] Remove mtime/mtimecmp

The RTC is now a device that lives on the MMIO bus.
---
 rocket/src/main/scala/csr.scala          | 12 +--------
 rocket/src/main/scala/instructions.scala | 34 ------------------------
 2 files changed, 1 insertion(+), 45 deletions(-)

diff --git a/rocket/src/main/scala/csr.scala b/rocket/src/main/scala/csr.scala
index 72270bf4..db17f67e 100644
--- a/rocket/src/main/scala/csr.scala
+++ b/rocket/src/main/scala/csr.scala
@@ -156,7 +156,6 @@ class CSRFile(implicit p: Parameters) extends CoreModule()(p)
   val reg_sbadaddr = Reg(UInt(width = vaddrBitsExtended))
   val reg_sscratch = Reg(Bits(width = xLen))
   val reg_stvec = Reg(UInt(width = vaddrBits))
-  val reg_mtimecmp = Reg(Bits(width = xLen))
   val reg_sptbr = Reg(UInt(width = ppnBits))
   val reg_wfi = Reg(init=Bool(false))
 
@@ -166,7 +165,6 @@ class CSRFile(implicit p: Parameters) extends CoreModule()(p)
   val reg_fflags = Reg(UInt(width = 5))
   val reg_frm = Reg(UInt(width = 3))
 
-  val reg_time = Reg(UInt(width = 64)) // regardless of XLEN
   val reg_instret = WideCounter(64, io.retire)
   val reg_cycle: UInt = if (enableCommitLog) { reg_instret } else { WideCounter(64) }
 
@@ -215,7 +213,6 @@ class CSRFile(implicit p: Parameters) extends CoreModule()(p)
     CSRs.mimpid -> UInt(0),
     CSRs.marchid -> UInt(0),
     CSRs.mvendorid -> UInt(0),
-    CSRs.mtime -> reg_time,
     CSRs.mcycle -> reg_cycle,
     CSRs.minstret -> reg_instret,
     CSRs.mucounteren -> UInt(0),
@@ -235,7 +232,6 @@ class CSRFile(implicit p: Parameters) extends CoreModule()(p)
     CSRs.mepc -> reg_mepc.sextTo(xLen),
     CSRs.mbadaddr -> reg_mbadaddr.sextTo(xLen),
     CSRs.mcause -> reg_mcause,
-    CSRs.mtimecmp -> reg_mtimecmp,
     CSRs.mhartid -> io.host.id,
     CSRs.mtohost -> reg_tohost,
     CSRs.mfromhost -> reg_fromhost)
@@ -276,7 +272,6 @@ class CSRFile(implicit p: Parameters) extends CoreModule()(p)
   }
 
   if (xLen == 32) {
-    read_mapping += CSRs.mtimeh -> (reg_time >> 32)
     read_mapping += CSRs.mcycleh -> (reg_cycle >> 32)
     read_mapping += CSRs.minstreth -> (reg_instret >> 32)
     read_mapping += CSRs.mutime_deltah -> UInt(0)
@@ -404,10 +399,7 @@ class CSRFile(implicit p: Parameters) extends CoreModule()(p)
 
   assert(PopCount(insn_ret :: io.exception :: csr_xcpt :: Nil) <= 1, "these conditions must be mutually exclusive")
 
-  when (reg_time >= reg_mtimecmp) {
-    reg_mip.mtip := true
-  }
-
+  reg_mip.mtip := io.host.timerIRQ
   io.time := reg_cycle
   io.csr_stall := reg_wfi
 
@@ -465,8 +457,6 @@ class CSRFile(implicit p: Parameters) extends CoreModule()(p)
       when (decoded_addr(CSRs.mtvec))  { reg_mtvec := wdata >> 2 << 2 }
     when (decoded_addr(CSRs.mcause))   { reg_mcause := wdata & UInt((BigInt(1) << (xLen-1)) + 31) /* only implement 5 LSBs and MSB */ }
     when (decoded_addr(CSRs.mbadaddr)) { reg_mbadaddr := wdata(vaddrBitsExtended-1,0) }
-    when (decoded_addr(CSRs.mtimecmp)) { reg_mtimecmp := wdata; reg_mip.mtip := false }
-    when (decoded_addr(CSRs.mtime))    { reg_time := wdata }
     when (decoded_addr(CSRs.mfromhost)){ when (reg_fromhost === UInt(0) || !host_csr_req_fire) { reg_fromhost := wdata } }
     when (decoded_addr(CSRs.mtohost))  { when (reg_tohost === UInt(0) || host_csr_req_fire) { reg_tohost := wdata } }
     if (usingFPU) {
diff --git a/rocket/src/main/scala/instructions.scala b/rocket/src/main/scala/instructions.scala
index d854fac8..84b0ed70 100644
--- a/rocket/src/main/scala/instructions.scala
+++ b/rocket/src/main/scala/instructions.scala
@@ -247,23 +247,6 @@ object CSRs {
   val cycle = 0xc00
   val time = 0xc01
   val instret = 0xc02
-  val stats = 0xc0
-  val uarch0 = 0xcc0
-  val uarch1 = 0xcc1
-  val uarch2 = 0xcc2
-  val uarch3 = 0xcc3
-  val uarch4 = 0xcc4
-  val uarch5 = 0xcc5
-  val uarch6 = 0xcc6
-  val uarch7 = 0xcc7
-  val uarch8 = 0xcc8
-  val uarch9 = 0xcc9
-  val uarch10 = 0xcca
-  val uarch11 = 0xccb
-  val uarch12 = 0xccc
-  val uarch13 = 0xccd
-  val uarch14 = 0xcce
-  val uarch15 = 0xccf
   val sstatus = 0x100
   val sie = 0x104
   val stvec = 0x105
@@ -330,23 +313,6 @@ object CSRs {
     res += cycle
     res += time
     res += instret
-    res += stats
-    res += uarch0
-    res += uarch1
-    res += uarch2
-    res += uarch3
-    res += uarch4
-    res += uarch5
-    res += uarch6
-    res += uarch7
-    res += uarch8
-    res += uarch9
-    res += uarch10
-    res += uarch11
-    res += uarch12
-    res += uarch13
-    res += uarch14
-    res += uarch15
     res += sstatus
     res += sie
     res += stvec