jtag: Prevent Debug RAM accesses from wrapping around, and bring the DTM closer to the Debug Spec

regression/Makefile

@@ -222,8 +222,8 @@ JTAG_DTM_TEST ?= SimpleRegisterTest.test_s0
 
 stamps/%/jtag-dtm-32-$(JTAG_DTM_TEST).stamp: install_openocd stamps/%/vsim-debug.stamp
 	$(abspath $(TOP))/riscv-tools/riscv-tests/debug/gdbserver.py \
-	--run "$(abspath $(TOP))/vsim/simv-$(PROJECT)-$*-debug +vcdplusfile=foo.vpd" \
+	--run "$(abspath $(TOP))/vsim/simv-$(PROJECT)-$*-debug +verbose +vcdplusfile=foo.vpd" \
-	--cmd="$(OPENOCD_DIR)/bin/openocd \
+	--cmd="$(OPENOCD_DIR)/bin/openocd -d \
 	--s $(OPENOCD_DIR)/share/openocd/scripts" \
 	--freedom-e300-sim \
 	$(JTAG_DTM_TEST)
@@ -232,7 +232,7 @@ stamps/%/jtag-dtm-32-$(JTAG_DTM_TEST).stamp: install_openocd stamps/%/vsim-debug
 stamps/%/jtag-dtm-64-$(JTAG_DTM_TEST).stamp: install_openocd stamps/%/vsim-debug.stamp
 	$(abspath $(TOP))/riscv-tools/riscv-tests/debug/gdbserver.py \
 	--run $(abspath $(TOP))/vsim/simv-$(PROJECT)-$* \
-	--cmd="$(OPENOCD_INSTALL)_$(OPENOCD_VERSION)/bin/openocd \
+	--cmd="$(OPENOCD_INSTALL)_$(OPENOCD_VERSION)/bin/openocd -d \
 	--s $(OPENOCD_INSTALL)_$(OPENOCD_VERSION)/share/openocd/scripts" \
 	--freedom-u500-sim \
 	$(JTAG_DTM_TEST)

src/main/scala/uncore/devices/Debug.scala

@@ -476,16 +476,23 @@ class DebugModule ()(implicit val p:cde.Parameters)
   val ramWrEn   = Wire(Bool())
 
   val dbRamAddr   = Wire(UInt(width=dbRamAddrWidth))
+  val dbRamAddrValid   = Wire(Bool())
   val dbRamRdData = Wire (UInt(width=dbRamDataWidth))
   val dbRamWrData = Wire(UInt(width=dbRamDataWidth))
   val dbRamWrEn   = Wire(Bool())
   val dbRamRdEn   = Wire(Bool())
+  val dbRamWrEnFinal   = Wire(Bool())
+  val dbRamRdEnFinal   = Wire(Bool())
 
   val sbRamAddr   = Wire(UInt(width=sbRamAddrWidth))
+  val sbRamAddrValid = Wire(Bool())
   val sbRamRdData = Wire (UInt(width=sbRamDataWidth))
   val sbRamWrData = Wire(UInt(width=sbRamDataWidth))
   val sbRamWrEn   = Wire(Bool())
   val sbRamRdEn   = Wire(Bool())
+  val sbRamWrEnFinal   = Wire(Bool())
+  val sbRamRdEnFinal   = Wire(Bool())
+
 
   val sbRomRdData       = Wire(UInt(width=tlDataBits))
   val sbRomAddrOffset   = log2Up(tlDataBits/8)
@@ -625,8 +632,18 @@ class DebugModule ()(implicit val p:cde.Parameters)
   //                                  0x40 - 0x6F Not Implemented
   dbRamAddr   := dbReq.addr( dbRamAddrWidth-1 , 0)
   dbRamWrData := dbReq.data
+  dbRamAddrValid := Bool(true)
+  if (dbRamAddrWidth < 4){
+    dbRamAddrValid := (dbReq.addr(3, dbRamAddrWidth) === UInt(0))
+  }
+
   sbRamAddr   := sbAddr(sbRamAddrWidth + sbRamAddrOffset - 1, sbRamAddrOffset)   
   sbRamWrData := sbWrData
+  sbRamAddrValid := Bool(true)
+  // From Specification: Debug RAM is 0x400 - 0x4FF
+  if ((sbRamAddrWidth + sbRamAddrOffset) < 8){
+    sbRamAddrValid := (sbAddr(7, sbRamAddrWidth + sbRamAddrOffset) === UInt(0))
+  }
 
   require (dbRamAddrWidth >= ramAddrWidth)    // SB accesses less than 32 bits Not Implemented.
   val dbRamWrMask = Wire(init=Vec.fill(1 << (dbRamAddrWidth - ramAddrWidth)){Fill(dbRamDataWidth, UInt(1, width=1))})
@@ -662,7 +679,7 @@ class DebugModule ()(implicit val p:cde.Parameters)
   ramRdData := ramMem(ramAddr)
   when (ramWrEn) { ramMem(ramAddr) := ramWrData }
 
-  ramWrEn := sbRamWrEn | dbRamWrEn
+  ramWrEn := sbRamWrEnFinal | dbRamWrEnFinal
   
   //--------------------------------------------------------------
   // Debug Bus Access
@@ -681,11 +698,15 @@ class DebugModule ()(implicit val p:cde.Parameters)
   CONTROLWrData := new CONTROLFields().fromBits(dbReq.data)
   RAMWrData     := new RAMFields().fromBits(dbReq.data)
 
-  dbRamWrEn  := Bool(false)
+  dbRamWrEn       := Bool(false)
-  CONTROLWrEn := Bool(false)
+  dbRamWrEnFinal  := Bool(false)
-  when ((dbReq.addr >> 4) === Bits(0)) {                   // 0x00 - 0x0F Debug RAM
+  CONTROLWrEn     := Bool(false)
+  when ((dbReq.addr >> 4) === Bits(0)) {  // 0x00 - 0x0F Debug RAM
     dbRamWrEn := dbWrEn
-   }.elsewhen (dbReq.addr === DMCONTROL) {
+    when (dbRamAddrValid) {
+      dbRamWrEnFinal := dbWrEn
+    }
+  }.elsewhen (dbReq.addr === DMCONTROL) {
     CONTROLWrEn  := dbWrEn
   }.otherwise {
     //Other registers/RAM are Not Implemented.
@@ -740,10 +761,14 @@ class DebugModule ()(implicit val p:cde.Parameters)
     }
   }
 
-  dbRamRdEn := Bool(false)
+  dbRamRdEn      := Bool(false)
-  when ((dbReq.addr >> 4) === Bits(0)) {       // 0x00 - 0x0F Debug RAM
+  dbRamRdEnFinal := Bool(false)
-    dbRdData  := RAMRdData.asUInt
+  when ((dbReq.addr >> 4) === Bits(0)) { // 0x00 - 0x0F Debug RAM
     dbRamRdEn := dbRdEn
+    when (dbRamAddrValid) {
+      dbRdData  := RAMRdData.asUInt
+      dbRamRdEnFinal := dbRdEn
+    }
   }.elsewhen (dbReq.addr === DMCONTROL) {
     dbRdData := CONTROLRdData.asUInt
   }.elsewhen (dbReq.addr === DMINFO) {
@@ -850,6 +875,7 @@ class DebugModule ()(implicit val p:cde.Parameters)
   // SB Access Write Decoder
 
   sbRamWrEn  := Bool(false)
+  sbRamWrEnFinal := Bool(false)
   SETHALTNOTWrEn := Bool(false)
   CLEARDEBINTWrEn := Bool(false)
 
@@ -859,6 +885,10 @@ class DebugModule ()(implicit val p:cde.Parameters)
     when (sbAddr(11, 8)   === UInt(4)){ // 0x400-0x4ff is Debug RAM
       sbRamWrEn := sbWrEn
       sbRamRdEn := sbRdEn
+      when (sbRamAddrValid) {
+        sbRamWrEnFinal := sbWrEn
+        sbRamRdEnFinal := sbRdEn
+      }
     }.elsewhen (sbAddr === SETHALTNOT){
       SETHALTNOTWrEn := sbWrEn
     }.elsewhen (sbAddr === CLEARDEBINT){
@@ -881,6 +911,10 @@ class DebugModule ()(implicit val p:cde.Parameters)
     when (sbAddr(11,8) === UInt(4)){ //0x400-0x4ff is Debug RAM
       sbRamWrEn := sbWrEn
       sbRamRdEn := sbRdEn
+      when (sbRamAddrValid){
+        sbRamWrEnFinal := sbWrEn
+        sbRamRdEnFinal := sbRdEn
+      }
     }
 
     SETHALTNOTWrEn := sbAddr(sbAddrWidth - 1, sbWrSelTop + 1) === SETHALTNOT(sbAddrWidth-1, sbWrSelTop + 1) &&
@@ -897,12 +931,15 @@ class DebugModule ()(implicit val p:cde.Parameters)
   // SB Access Read Mux
  
   sbRdData := UInt(0)
-  sbRamRdEn := Bool(false)
+  sbRamRdEn      := Bool(false)
+  sbRamRdEnFinal := Bool(false)
 
-  dbRamRdEn := Bool(false)
   when (sbAddr(11, 8) === UInt(4)) {                                 //0x400-0x4FF Debug RAM
-    sbRdData  := sbRamRdData
     sbRamRdEn := sbRdEn
+    when (sbRamAddrValid) {
+      sbRdData  := sbRamRdData
+      sbRamRdEnFinal := sbRdEn
+    }
   }.elsewhen (sbAddr(11,8).isOneOf(UInt(8), UInt(9))){ //0x800-0x9FF Debug ROM
     if (cfg.hasDebugRom) {
       sbRdData := sbRomRdData

vsrc/DebugTransportModuleJtag.v

@@ -9,7 +9,7 @@ module DebugTransportModuleJtag (
                                  jtag_TCK,
                                  jtag_TMS,
                                  jtag_TRST,
-                                 
+                             
                                  jtag_DRV_TDO,
 
                                  dtm_req_valid,
@@ -27,15 +27,22 @@ module DebugTransportModuleJtag (
    parameter DEBUG_DATA_BITS  = 34;
    parameter DEBUG_ADDR_BITS = 5; // Spec allows values are 5-7 
    parameter DEBUG_OP_BITS = 2; // OP and RESP are the same size.
-      
+
    parameter JTAG_VERSION  = 4'h1;
    parameter JTAG_PART_NUM = 16'h0E31; // E31
    parameter JTAG_MANUF_ID = 11'h489;  // As Assigned by JEDEC
-   
+
+   // Number of cycles which must remain in IDLE
+   // The software should handle even if the
+   // answer is actually higher than this, or
+   // the software may choose to ignore it entirely
+   // and just check for busy.
+   parameter DBUS_IDLE_CYCLES = 3'h5;
+
    localparam IR_BITS = 5;
 
    localparam DEBUG_VERSION = 0;
-
+   
    // JTAG State Machine
    localparam TEST_LOGIC_RESET  = 4'h0;
    localparam RUN_TEST_IDLE     = 4'h1;
@@ -78,16 +85,15 @@ module DebugTransportModuleJtag (
    input                                jtag_TMS;
    input                                jtag_TRST;
 
-   
    // To allow tri-state outside of this block.
    output reg                           jtag_DRV_TDO;
 
    // RISC-V Core Side
-   
+
    output                               dtm_req_valid;
    input                                dtm_req_ready;
    output [DBUS_REQ_BITS - 1 :0]        dtm_req_bits;
-   
+
    input                                dtm_resp_valid;
    output                               dtm_resp_ready;
    input [DBUS_RESP_BITS - 1 : 0]        dtm_resp_bits;
@@ -110,9 +116,11 @@ module DebugTransportModuleJtag (
    reg                                  doDbusReadReg;
 
    reg                                  busyReg;
+   reg                                  stickyBusyReg;
+   reg                                  stickyNonzeroRespReg;
+      
    reg                                  skipOpReg; // Skip op because we're busy.
    reg                                  downgradeOpReg; // Downgrade op because prev. op failed.
-   
 
    wire                                 busy;
    wire                                 nonzeroResp;
@@ -127,15 +135,31 @@ module DebugTransportModuleJtag (
 
    wire [3:0]                           debugAddrBits = DEBUG_ADDR_BITS[3:0];
    wire [3:0]                           debugVersion = DEBUG_VERSION[3:0];
+
+   wire [1:0]                           dbusStatus;
+   wire [2:0]                           dbusIdleCycles;
+
+   wire                                 dbusReset;
    
-   assign dtminfo = {24'b0, debugAddrBits, debugVersion};
+   assign dbusIdleCycles = DBUS_IDLE_CYCLES;
+   assign dbusStatus = {stickyNonzeroRespReg, stickyNonzeroRespReg | stickyBusyReg};
+   assign dbusReset = shiftReg[16];
+
+   assign dtminfo = {15'b0,
+                     1'b0, // dbusreset goes here but is write-only
+                     3'b0, 
+                     dbusIdleCycles, 
+                     dbusStatus, 
+                     debugAddrBits, 
+                     debugVersion};
    
    //busy, dtm_resp* is only valid during CAPTURE_DR,
    //      so these signals should only be used at that time.
    // This assumes there is only one transaction in flight at a time.
-   assign busy = busyReg & ~dtm_resp_valid;
+   assign busy = (busyReg & ~dtm_resp_valid); // | stickyBusyReg;
    // This is needed especially for the first request.
-   assign nonzeroResp = dtm_resp_valid ? |{dtm_resp_bits[DEBUG_OP_BITS-1:0]} : 1'b0;
+   assign nonzeroResp = (dtm_resp_valid ? |{dtm_resp_bits[DEBUG_OP_BITS-1:0]} : 1'b0);
+   //stickyNonzeroRespReg;
    
    // Interface to DM.
    // Note that this means dtm_resp_bits must only be used during CAPTURE_DR.
@@ -158,7 +182,7 @@ module DebugTransportModuleJtag (
    // Sequential Logic
 
    // JTAG STATE MACHINE
-   
+
    always @(posedge jtag_TCK or posedge jtag_TRST) begin
       if (jtag_TRST) begin
          jtagStateReg <= TEST_LOGIC_RESET;
@@ -239,19 +263,32 @@ module DebugTransportModuleJtag (
    // during every CAPTURE_DR, and use the result in UPDATE_DR.
    always @(posedge jtag_TCK or posedge jtag_TRST) begin
       if (jtag_TRST) begin
-         skipOpReg      <= 1'b0;
+         skipOpReg            <= 1'b0;
-         downgradeOpReg <= 1'b0;
+         downgradeOpReg       <= 1'b0;
+         stickyBusyReg        <= 1'b0;
+         stickyNonzeroRespReg <= 1'b0;
       end else if (irReg == REG_DEBUG_ACCESS) begin
          case(jtagStateReg)
            CAPTURE_DR: begin
               skipOpReg      <= busy;
               downgradeOpReg <= (~busy & nonzeroResp);
+              stickyBusyReg  <= busy;
+              stickyNonzeroRespReg <= nonzeroResp;
            end
            UPDATE_DR: begin
               skipOpReg      <= 1'b0;
               downgradeOpReg <= 1'b0;
            end
          endcase // case (jtagStateReg)
+      end else if (irReg == REG_DTM_INFO) begin
+         case(jtagStateReg)
+           UPDATE_DR: begin
+              if (dbusReset) begin
+                 stickyNonzeroRespReg <= 1'b0;
+                 stickyBusyReg        <= 1'b0;
+              end
+           end
+         endcase // case (jtagStateReg)
       end
    end // always @ (posedge jtag_TCK or posedge jtag_TRST)