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// ----------------------------------------------------------------------------

// SystemC OpenRISC 1000 Debug Unit: implementation

// Copyright (C) 2008  Embecosm Limited <info@embecosm.com>

// Copyright (C) 2009  ORSoC

// Contributor Jeremy Bennett <jeremy.bennett@embecosm.com>

// Contributor Julius Baxter <julius@orsoc.se>

// This file is part of the GDB interface to the cycle accurate model of the

// OpenRISC 1000 based system-on-chip, ORPSoC, built using Verilator.

// This program is free software: you can redistribute it and/or modify it

// under the terms of the GNU Lesser General Public License as published by

// the Free Software Foundation, either version 3 of the License, or (at your

// option) any later version.

// This program is distributed in the hope that it will be useful, but WITHOUT

// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public

// License for more details.

// You should have received a copy of the GNU Lesser General Public License

// along with this program.  If not, see <http://www.gnu.org/licenses/>.

// ----------------------------------------------------------------------------

// $Id$

#include <iostream>

#include <iomanip>

#include "DebugUnitSC.h"

#include "Utils.h"

using sc_core::sc_event;

using sc_core::sc_fifo;

using sc_core::sc_module_name;

//-----------------------------------------------------------------------------

//! Constructor for the Debug Unit

//! This module is entirely subservient to the GDB server. It has no SystemC

//! processes of its own. It provides services via calls to its API.

//! The current scan chain is marked as undefined, and the current JTAG scan

//! chain is maked as undefined.

//! Caches for SPR and memory access are initialized.

//! This makes use of the Embecosm cycle accurate SystemC JTAG interface.

//! @see Embecosm Application Note 5 "Using JTAG with SystemC: Implementation

//!      of a Cycle Accurate Interface"

//!      (http://www.embecosm.com/download/ean5.html)

//! @param[in] name             Name of this module, passed to the parent

//!                             constructor. 

//! @param[in] _tapActionQueue  Pointer to fifo of actions to be performed by

//!                             the JTAG interface

//-----------------------------------------------------------------------------

DebugUnitSC::DebugUnitSC (sc_module_name        name,

                          sc_fifo<TapAction *> *_tapActionQueue) :

  sc_module (name),

  tapActionQueue (_tapActionQueue),

  stallState (UNKNOWN),

  currentScanChain (OR1K_SC_UNDEF)

{

#ifdef NOCACHE

  npcCacheIsValid = false;              // Always cache NPC

#else

  sprCache = new SprCache ();

  memCache = new MemCache ();

#endif

}       // DebugUnitSC ()

//-----------------------------------------------------------------------------

//! Destructor

//! Free up data structures

//-----------------------------------------------------------------------------

DebugUnitSC::~DebugUnitSC ()

{

#ifndef NOCACHE

  delete  memCache;

  delete  sprCache;

#endif

}       // ~DebugUnitSC

//-----------------------------------------------------------------------------

//! Reset the Debug Unit

//! This is just a reset of the JTAG. It is quite possible to reset the debug

//! unit without resetting the whole target.

//! @note Must be called from a SystemC thread, because of the use of wait()

//-----------------------------------------------------------------------------

void

DebugUnitSC::resetDebugUnit ()

{

  sc_event       *done = new sc_event();

  TapActionReset *resetAction;

  // Create and queue the reset action and wait for it to complete

  resetAction = new TapActionReset (done);

  tapActionQueue->write (resetAction);

  wait (*done);

  delete resetAction;

  delete done;

}       // resetDebugUnit ()

//-----------------------------------------------------------------------------

//! Reset the processor

//! Read the RISCOP register, OR in the reset bit and write it back.

//! After reset, the processor is known to be unstalled.

//-----------------------------------------------------------------------------

void

DebugUnitSC::reset ()

{

  writeRiscop (readRiscop () | RISCOP_RESET);

  stallState = UNKNOWN;

}       // reset ()

//-----------------------------------------------------------------------------

//! Stall the processor

//! Read the RISCOP register, OR in the stall bit and write it back.

//-----------------------------------------------------------------------------

void

DebugUnitSC::stall ()

{

  writeRiscop (/*readRiscop () |*/ RISCOP_STALL);

  stallState = STALLED;

}       // stall ()

//-----------------------------------------------------------------------------

//! Unstall the processor

//! Read the RISCOP register, AND out the stall bit and write it back. After

//! this the NPC cache will be invalid.

//! @note Don't be tempted to read back for confirmation. Single stepping

//!       will already have stalled the processor again!

//-----------------------------------------------------------------------------

void

DebugUnitSC::unstall ()

{

  writeRiscop (/*readRiscop () & ~RISCOP_STALL*/ 0);

  stallState  = UNKNOWN;

#ifdef NOCACHE

  npcCacheIsValid = false;              // Always cache NPC

#else

  // Clear the caches

  sprCache->clear ();

  memCache->clear ();

#endif

}       // unstall ()

//-----------------------------------------------------------------------------

//! Report if the processor is stalled.

//! A stalled processor cannot spontaneously "unstall", so if the stallState

//! flag is STALLED, that value is returned. Otherwise the target is

//! interrogated to determine the status.

//! @return  TRUE if the processor is known to be stalled

//-----------------------------------------------------------------------------

bool

DebugUnitSC::isStalled ()

{

  if (STALLED == stallState)

    {

      return  true;

    }

  uint32_t  riscop = readRiscop ();

  /* For some reason the reset bit is skipped over somewhere, so we should

     just get riscop = 1 if it's stalled */

  //stallState = (RISCOP_STALL == (riscop & RISCOP_STALL)) ? STALLED : UNKNOWN;

  stallState = riscop ? STALLED : UNKNOWN;

  return  STALLED == stallState;

}       // isStalled ()

//-----------------------------------------------------------------------------

//! Read the value of an OpenRISC 1000 Special Purpose Register

//! First see if we have the value in the cache, and if so return

//! it. Otherwise, select the RISC_DEBUG scan chain and read from JTAG,

//! storing the result in the cache.

//! @param[in]  sprNum  The SPR to read

//! @return  The value of the SPR

//-----------------------------------------------------------------------------

uint32_t

DebugUnitSC::readSpr (uint16_t  sprNum)

{

  uint32_t  cachedValue;

#ifdef NOCACHE

  // Always check NPC cache

  if ((STALLED == stallState) && (sprNum == SPR_NPC) && npcCacheIsValid)

    {

      return  npcCachedValue;

    }

#else

  // Use any cached value if we are stalled.

  if ((STALLED == stallState) && sprCache->read (sprNum, cachedValue))

    {

      return  cachedValue;              // Already there, no more to do

    }

#endif

  // Read the value

  selectDebugModule (OR1K_SC_CPU0);

  cachedValue = readJtagReg (sprNum);

#ifdef NOCACHE

  // Always update the NPC cache

  if ((STALLED == stallState) && (sprNum == SPR_NPC))

    {

      npcCachedValue  = cachedValue;

      npcCacheIsValid = true;

    }

#else

  // Update the cache if we are stalled

  if (STALLED == stallState)

    {

      sprCache->write (sprNum, cachedValue, sprNum == SPR_NPC);

    }

#endif

  return  cachedValue;

}       // readSpr ()

//-----------------------------------------------------------------------------

//! Write the value of an OpenRISC 1000 Special Purpose Register

//! First look to see if we are stalled and the value is cached. If the value

//! has not changed, then we need to no more. Otherwise cache the value prior

//! to writing it.

//! Select the RISC_DEBUG scan chain and write to JTAG

//! @param[in] sprNum  The SPR to write

//! @param[in] value   The value to write

//-----------------------------------------------------------------------------

void

DebugUnitSC::writeSpr (uint16_t  sprNum,

                       uint32_t  value)

{

#ifdef NOCACHE

  // Always cache the NPC

  if ((STALLED == stallState) && (SPR_NPC == sprNum))

    {

      // Have we already cached this NPC value?

      if (npcCacheIsValid && (value == npcCachedValue))

        {

          return;

        }

      else

        {

          npcCachedValue  = value;

          npcCacheIsValid = true;

        }

    }

#else

  if (STALLED == stallState)

    {

      // Have we already cached this value?

      uint32_t  cachedValue;

      if (sprCache->read (sprNum, cachedValue) &&

          (value == cachedValue))

        {

          return;                               // Already there, no more to do

        }

      else

        {

          sprCache->write (sprNum, value, sprNum == SPR_NPC);

        }

    }

#endif

  // Write the SPR

  selectDebugModule (OR1K_SC_CPU0);

  writeJtagReg (sprNum, value);

}       // writeSpr ()

//-----------------------------------------------------------------------------

//! AND the contents of an SPR with a value

//! A convenience combination of read and write

//! @param[in] sprNum  The SPR to write

//! @param[in] value   The value to AND into the register

//-----------------------------------------------------------------------------

void

DebugUnitSC::andSpr (uint16_t  sprNum,

                     uint32_t  value)

{

  writeSpr (sprNum, readSpr (sprNum) & value);

}       // andSpr ()

//-----------------------------------------------------------------------------

//! OR the contents of an SPR with a value

//! A convenience combination of read and write

//! @param[in] sprNum  The SPR to write

//! @param[in] value   The value to OR into the register

//-----------------------------------------------------------------------------

void

DebugUnitSC::orSpr (uint16_t  sprNum,

                   uint32_t  value)

{

  writeSpr (sprNum, readSpr (sprNum) | value);

}       // orSpr ()

//-----------------------------------------------------------------------------

//! Read a 32-bit word from the OpenRISC 1000 memory

//! Select the WISHBONE scan chain, then write the register. The data is in

//! model endianness and passed on without modification.

//! @todo Provide code to check if the read was from a valid address.

//! @param[in] addr  The address to read from

//! @return  The 32-bit value read

//-----------------------------------------------------------------------------

uint32_t

DebugUnitSC::readMem32 (uint32_t  addr)

{

  uint32_t  cachedValue;

#ifndef NOCACHE

  // Use any cached value if we are stalled.

  if ((STALLED == stallState) && memCache->read (addr, cachedValue))

    {

      return  cachedValue;              // Already there, no more to do

    }

#endif

  // Read the value

  selectDebugModule (OR1K_SC_WISHBONE);

  cachedValue = readJtagReg (addr);

#ifndef NOCACHE

  // Update the cache if we are stalled

  if (STALLED == stallState)

    {

      memCache->write (addr, cachedValue);

    }

#endif

  return  cachedValue;

}       // readMem32 ()

//-----------------------------------------------------------------------------

//! Write a 32-bit word to the OpenRISC 1000 memory

//! Select the WISHBONE scan chain, then write the register. The data is in

//! model endianness and passed on without modification.

//! @todo Provide code to check if the write was to a valid address.

//! @param[in] addr   The address to write to

//! @param[in] value  The 32-bit value to write

//! @return  True if the write was successful. For now all writes are

//           successful.

//-----------------------------------------------------------------------------

bool

DebugUnitSC::writeMem32 (uint32_t  addr,

                         uint32_t  value)

{

#ifndef NOCACHE

  if (STALLED == stallState)

    {

      // Have we already cached this value?

      uint32_t  cachedValue;

      if (memCache->read (addr, cachedValue) &&

          (value == cachedValue))

        {

          return  true;                         // Already there, no more to do

        }

      else

        {

          memCache->write (addr, value);        // Write for the future

        }

    }

#endif

  // Write the memory

  selectDebugModule (OR1K_SC_WISHBONE);

  writeJtagReg (addr, value);

  return  true;

}       // writeMem32 ()

//-----------------------------------------------------------------------------

//! Read a byte from the OpenRISC 1000 main memory

//! All we can get are 32-bits words, so we have to unpick the value.

//! The underlying 32-bit routines take target endian arguments and return

//! target endian results. We need to convert to host endianness to access the

//! relevant byte.

//! @todo Provide code to check if the read was from a valid address.

//! @note Read bytes from memory mapped devices at your peril!

//! @param[in] addr  The address to read from

//! @return  The byte read

//-----------------------------------------------------------------------------

uint8_t

DebugUnitSC::readMem8 (uint32_t  addr)

{

  uint32_t  word   = Utils::ttohl (readMem32 (addr & 0xfffffffc));

  uint8_t  *bytes  = (uint8_t *)(&word);

  int       offset = addr & 0x3;

  return  bytes[offset];

}       // readMem8 ()

//-----------------------------------------------------------------------------

//! Write a byte to the OpenRISC 1000 main memory

//! All we can get are 32-bits words, so we have to read the current value and

//! construct the new value to write back.

//! The underlying 32-bit routines take target endian arguments and return

//! target endian results. We need to convert to host endianness to alter the

//! relevant byte.

//! @note Write bytes to memory mapped devices at your peril!

//! @todo Provide code to check if the write was to a valid address.

//! @param[in] addr   The address to write to

//! @param[in] value  The byte to write

//! @return  True if the write was successful. For now all writes are

//           successful.

//-----------------------------------------------------------------------------

bool

DebugUnitSC::writeMem8 (uint32_t  addr,

                        uint8_t   value)

{

  uint32_t  currWord  = Utils::ttohl (readMem32 (addr & 0xfffffffc));

  uint8_t  *currBytes = (uint8_t *)(&currWord);

  int       offset    = addr & 0x3;

  currBytes[offset] = value;

  return  writeMem32 (addr & 0xfffffffc, Utils::htotl (currWord));

}       // writeMem8 ()

//-----------------------------------------------------------------------------

//! Get the debug interface CPU0 control register value

//! @return  The value in the RISCOP register

//-----------------------------------------------------------------------------

uint32_t

DebugUnitSC::readRiscop ()

{

  selectDebugModule (OR1K_SC_CPU0);

  int  drLen;                   // Size of the data register

  uint32_t calc_recv_crc = 0, recv_crc, status_ret;

  drLen = 1+4+32+52+4+32;

  // Initialize the register fields

  uint64_t *dRegIn  = new uint64_t [(drLen + 63) / 64];

  uint64_t *dRegOut = new uint64_t [(drLen + 63) / 64];

  // Write the READ command

  clearBits (dRegIn, drLen);

  packBits (dRegIn, 0, 1, 0);

  packBits (dRegIn, 0+1, 4, BITREV(0x3,4)); // We're reading CPU0 control reg

  uint32_t crc32_send = crc32 (dRegIn, 0+1+4, 0);

  packBits (dRegIn, 0+1+4, 32, BITREV(crc32_send,32));

  // Allocate a SystemC completion event

  sc_event *done  = new sc_event();

  // Loop until status is OK and CRCs match.

  do

    {

      TapActionDRScan *dRScan = new TapActionDRScan (done, dRegIn, drLen);

      tapActionQueue->write (dRScan);

      wait (*done);

      dRScan->getDRegOut (dRegOut);

      delete dRScan;

      status_ret = unpackBits (dRegOut,1+4+32+52,4);

      calc_recv_crc = crc32(dRegOut,52+4,1+4+32);

      recv_crc = BITREV(unpackBits (dRegOut,1+4+32+52+4,32),32);

    }

  while ((0 != status_ret) || ( calc_recv_crc != recv_crc));

  // All done

  uint32_t  res = BITREV(unpackBits (dRegOut, (1+4+32),2),2);

  delete [] dRegIn;

  delete [] dRegOut;

  delete  done;

  return  res;

}       // readRiscop ()

//-----------------------------------------------------------------------------

//! Set the RISCOP control register

//! Convenience function. Select the REGISTER scan chain, write the new value.

//! @param[in] value  The value to write into the RISCOP register

//-----------------------------------------------------------------------------

void

DebugUnitSC::writeRiscop (uint32_t  value)

{

  selectDebugModule (OR1K_SC_CPU0);

  int  drLen;                   // Size of the data register

  uint32_t calc_recv_crc = 0, recv_crc, status_ret;

  drLen = 1+4+32+52+4+32;

  // Initialize the register fields

  uint64_t *dRegIn  = new uint64_t [(drLen + 63) / 64];

  uint64_t *dRegOut = new uint64_t [(drLen + 63) / 64];

  // Write the READ command

  clearBits (dRegIn, drLen);

  packBits (dRegIn, 0, 1, 0);

  packBits (dRegIn, 0+1, 4, BITREV(0x4,4)); // We're writing CPU0 control reg

  packBits (dRegIn, 5, 1, value&RISCOP_RESET); // First bit is reset

  packBits (dRegIn, 6, 1, (value&RISCOP_STALL)>>1); // Next bit is stall

  /* Next 50 bits should be zero */

  uint32_t crc32_send = crc32 (dRegIn, 1+4+52, 0);

  packBits (dRegIn, 1+4+52, 32, BITREV(crc32_send,32));

  // Allocate a SystemC completion event

  sc_event *done  = new sc_event();

  // Loop until status is OK and CRCs match.

  do

    {

      TapActionDRScan *dRScan = new TapActionDRScan (done, dRegIn, drLen);

      tapActionQueue->write (dRScan);

      wait (*done);

      dRScan->getDRegOut (dRegOut);

      delete dRScan;

      status_ret = unpackBits (dRegOut,1+4+32+52,4);

      calc_recv_crc = crc32(dRegOut,4,1+4+52+32);

      recv_crc = BITREV(unpackBits (dRegOut,1+4+52+32+4,32),32);

    }

  while ((0 != status_ret) || ( calc_recv_crc != recv_crc));

  delete [] dRegIn;

  delete [] dRegOut;

  delete  done;

}       // writeRiscop ()

//-----------------------------------------------------------------------------

//! Select a module attached to the debug module

//! @note Must be called from a SystemC thread, because of the use of wait()

//! @param[in] chain  The desired module

//-----------------------------------------------------------------------------

void

DebugUnitSC::selectDebugModule (int module)

{

  if (module == currentScanChain)

    {

      return;

    }

  else

    {

      currentScanChain = module;

    }

  sc_event        *done = new sc_event();

  TapActionIRScan *iRScan;

  TapActionDRScan *dRScan;

  // Create and queue the IR-Scan action for DEBUG (no CRC)

  iRScan      = new TapActionIRScan (done, DEBUG_IR, JTAG_IR_LEN);

  tapActionQueue->write (iRScan);

  wait (*done);

  delete iRScan;

  // Initialize the register fields

  uint64_t *dRegIn  = new uint64_t [(DUSEL_DR_LEN + 63) / 64];

  uint64_t *dRegOut = new uint64_t [(DUSEL_DR_LEN + 63) / 64];

  clearBits (dRegIn, DUSEL_DR_LEN);

  packBits (dRegIn, DUSEL_SEL_OFF, DUSEL_SEL_LEN, 0x1);

  packBits (dRegIn, DUSEL_OPCODE_OFF, DUSEL_OPCODE_LEN, bit_reverse_data(module,4));

  uint32_t crc32_send = crc32 (dRegIn, DUSEL_CRC_OFF, 0);

  packBits (dRegIn, DUSEL_CRC_OFF, DUSEL_CRC_LEN, bit_reverse_data(crc32_send,32) );

  uint32_t calc_recv_crc = 0, recv_crc, status_ret;

  // Loop until status is OK and CRCs match.

  do

    {

      TapActionDRScan *dRScan = new TapActionDRScan (done, dRegIn, DUSEL_DR_LEN);

      tapActionQueue->write (dRScan);

      wait (*done);

      dRScan->getDRegOut (dRegOut);

      delete dRScan;

      status_ret = unpackBits (dRegOut, DUSEL_RESP_STATUS_OFF, DUSEL_RESP_STATUS_LEN);

      calc_recv_crc = crc32(dRegOut, DUSEL_RESP_STATUS_LEN, DUSEL_RESP_STATUS_OFF);

      recv_crc = bit_reverse_data(unpackBits (dRegOut, DUSEL_RESP_CRC_OFF, DUSEL_RESP_CRC_LEN),32);

    }

  while ((0 != status_ret) || ( calc_recv_crc != recv_crc));

  delete [] dRegIn;

  delete [] dRegOut;

  delete done;

}       // selectDebugModule()

//-----------------------------------------------------------------------------

//! Read a 32-bit value via the debug interface

//! @note Must be called from a SystemC thread, because of the use of wait()

//! @param[in] addr  The address of the register

//! @return  The register value read

//-----------------------------------------------------------------------------

uint32_t

DebugUnitSC::readJtagReg (uint32_t  addr)

{

  int  drLen;                   // Size of the data register

  uint32_t calc_recv_crc = 0, recv_crc, status_ret;

  drLen = 125; // Size of write command command (bigger than data read)

  // Initialize the register fields

  uint64_t *dRegIn  = new uint64_t [(drLen + 63) / 64];

  uint64_t *dRegOut = new uint64_t [(drLen + 63) / 64];

  // Write the READ command

  clearBits (dRegIn, drLen);

  packBits (dRegIn, 0, 1, 0);

  packBits (dRegIn, 0+1, 4, BITREV(0x2,4)); // We're writing a command

  packBits (dRegIn, 1+4, 4, BITREV(0x6,4)); // Access type, 0x6 = 32-bit READ

  packBits (dRegIn, 1+4+4, 32, BITREV(addr,32)); // Address

  packBits (dRegIn, 1+4+4+32, 16, BITREV(0x3,16)); // Length (always 32-bit,n=(32/8)-1=3)

  uint32_t crc32_send = crc32 (dRegIn, 1+4+4+32+16, 0);

  packBits (dRegIn, 1+4+4+32+16, 32, BITREV(crc32_send,32));

  // Allocate a SystemC completion event

  sc_event *done  = new sc_event();

  // Loop until status is OK and CRCs match.

  do

    {

      TapActionDRScan *dRScan = new TapActionDRScan (done, dRegIn, 125);

      tapActionQueue->write (dRScan);

      wait (*done);

      dRScan->getDRegOut (dRegOut);

      delete dRScan;

      status_ret = unpackBits (dRegOut,1+4+4+32+16+32,4);

      calc_recv_crc = crc32(dRegOut,4,1+4+4+32+16+32);