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/* dmmu.c -- Data MMU simulation

   Copyright (C) 1999 Damjan Lampret, lampret@opencores.org

   Copyright (C) 2008 Embecosm Limited

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

   This file is part of Or1ksim, the OpenRISC 1000 Architectural Simulator.

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

   under the terms of the GNU 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 General Public License for

   more details.

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

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

/* This program is commented throughout in a fashion suitable for processing

   with Doxygen. */

/* DMMU model, perfectly functional. */

/* Autoconf and/or portability configuration */

#include "config.h"

#include "port.h"

/* System includes */

#include <stdlib.h>

/* Package includes */

#include "dmmu.h"

#include "sim-config.h"

#include "arch.h"

#include "execute.h"

#include "spr-defs.h"

#include "stats.h"

#include "except.h"

#include "sprs.h"

#include "misc.h"

#include "sim-cmd.h"

struct dmmu *dmmu_state;

/* Data MMU */

static uorreg_t *

dmmu_find_tlbmr (oraddr_t virtaddr, uorreg_t ** dtlbmr_lru, struct dmmu *dmmu)

{

  int set;

  int i;

  oraddr_t vpn;

  uorreg_t *dtlbmr;

  /* Which set to check out? */

  set = DADDR_PAGE (virtaddr) >> dmmu->pagesize_log2;

  set &= dmmu->set_mask;

  vpn = virtaddr & dmmu->vpn_mask;

  dtlbmr = &cpu_state.sprs[SPR_DTLBMR_BASE (0) + set];

  *dtlbmr_lru = dtlbmr;

  /* FIXME: Should this be reversed? */

  for (i = dmmu->nways; i; i--, dtlbmr += (128 * 2))

    {

      if (((*dtlbmr & dmmu->vpn_mask) == vpn) && (*dtlbmr & SPR_DTLBMR_V))

        return dtlbmr;

    }

  return NULL;

}

oraddr_t

dmmu_translate (oraddr_t virtaddr, int write_access)

{

  int i;

  uorreg_t *dtlbmr;

  uorreg_t *dtlbtr;

  uorreg_t *dtlbmr_lru;

  struct dmmu *dmmu = dmmu_state;

  if (!(cpu_state.sprs[SPR_SR] & SPR_SR_DME) ||

      !(cpu_state.sprs[SPR_UPR] & SPR_UPR_DMP))

    {

      data_ci = (virtaddr >= 0x80000000);

      return virtaddr;

    }

  dtlbmr = dmmu_find_tlbmr (virtaddr, &dtlbmr_lru, dmmu);

  /* Did we find our tlb entry? */

  if (dtlbmr)

    {                           /* Yes, we did. */

      dmmu_stats.loads_tlbhit++;

      dtlbtr = dtlbmr + 128;

      /* Set LRUs */

      for (i = 0; i < dmmu->nways; i++, dtlbmr_lru += (128 * 2))

        {

          if (*dtlbmr_lru & SPR_DTLBMR_LRU)

            *dtlbmr_lru = (*dtlbmr_lru & ~SPR_DTLBMR_LRU) |

              ((*dtlbmr_lru & SPR_DTLBMR_LRU) - 0x40);

        }

      /* This is not necessary `*dtlbmr &= ~SPR_DTLBMR_LRU;' since SPR_DTLBMR_LRU

       * is always decremented and the number of sets is always a power of two and

       * as such lru_reload has all bits set that get touched during decrementing

       * SPR_DTLBMR_LRU */

      *dtlbmr |= dmmu->lru_reload;

      /* Check if page is cache inhibited */

      data_ci = *dtlbtr & SPR_DTLBTR_CI;

      runtime.sim.mem_cycles += dmmu->hitdelay;

      /* Test for page fault */

      if (cpu_state.sprs[SPR_SR] & SPR_SR_SM)

        {

          if ((write_access && !(*dtlbtr & SPR_DTLBTR_SWE))

              || (!write_access && !(*dtlbtr & SPR_DTLBTR_SRE)))

            except_handle (EXCEPT_DPF, virtaddr);

        }

      else

        {

          if ((write_access && !(*dtlbtr & SPR_DTLBTR_UWE))

              || (!write_access && !(*dtlbtr & SPR_DTLBTR_URE)))

            except_handle (EXCEPT_DPF, virtaddr);

        }

      return (*dtlbtr & SPR_DTLBTR_PPN) | (virtaddr &

                                           (dmmu->page_offset_mask));

    }

  /* No, we didn't. */

  dmmu_stats.loads_tlbmiss++;

#if 0

  for (i = 0; i < dmmu->nways; i++)

    if (((cpu_state.sprs[SPR_DTLBMR_BASE (i) + set] & SPR_DTLBMR_LRU) >> 6) <

        minlru)

      minway = i;

  cpu_state.sprs[SPR_DTLBMR_BASE (minway) + set] &= ~SPR_DTLBMR_VPN;

  cpu_state.sprs[SPR_DTLBMR_BASE (minway) + set] |= vpn << 12;

  for (i = 0; i < dmmu->nways; i++)

    {

      uorreg_t lru = cpu_state.sprs[SPR_DTLBMR_BASE (i) + set];

      if (lru & SPR_DTLBMR_LRU)

        {

          lru = (lru & ~SPR_DTLBMR_LRU) | ((lru & SPR_DTLBMR_LRU) - 0x40);

          cpu_state.sprs[SPR_DTLBMR_BASE (i) + set] = lru;

        }

    }

  cpu_state.sprs[SPR_DTLBMR_BASE (way) + set] &= ~SPR_DTLBMR_LRU;

  cpu_state.sprs[SPR_DTLBMR_BASE (way) + set] |= (dmmu->nsets - 1) << 6;

  /* 1 to 1 mapping */

  cpu_state.sprs[SPR_DTLBTR_BASE (minway) + set] &= ~SPR_DTLBTR_PPN;

  cpu_state.sprs[SPR_DTLBTR_BASE (minway) + set] |= vpn << 12;

  cpu_state.sprs[SPR_DTLBMR_BASE (minway) + set] |= SPR_DTLBMR_V;

#endif

  runtime.sim.mem_cycles += dmmu->missdelay;

  /* if tlb refill implemented in HW */

  /* return ((cpu_state.sprs[SPR_DTLBTR_BASE(minway) + set] & SPR_DTLBTR_PPN) >> 12) * dmmu->pagesize + (virtaddr % dmmu->pagesize); */

  except_handle (EXCEPT_DTLBMISS, virtaddr);

  return 0;

}

/* DESC: try to find EA -> PA transaltion without changing

 *       any of precessor states. if this is not passible gives up

 *       (without triggering exceptions)

 *

 * PRMS: virtaddr     - EA for which to find translation

 *

 *       write_access - 0 ignore testing for write access

 *                      1 test for write access, if fails

 *                        do not return translation

 *

 *       through_dc   - 1 go through data cache

 *                      0 ignore data cache

 *

 * RTRN: 0            - no DMMU, DMMU disabled or ITLB miss

 *       else         - appropriate PA (note it DMMU is not present

 *                      PA === EA)

 */

oraddr_t

peek_into_dtlb (oraddr_t virtaddr, int write_access, int through_dc)

{

  uorreg_t *dtlbmr;

  uorreg_t *dtlbtr;

  uorreg_t *dtlbmr_lru;

  struct dmmu *dmmu = dmmu_state;

  if (!(cpu_state.sprs[SPR_SR] & SPR_SR_DME) ||

      !(cpu_state.sprs[SPR_UPR] & SPR_UPR_DMP))

    {

      if (through_dc)

        data_ci = (virtaddr >= 0x80000000);

      return virtaddr;

    }

  dtlbmr = dmmu_find_tlbmr (virtaddr, &dtlbmr_lru, dmmu);

  /* Did we find our tlb entry? */

  if (dtlbmr)

    {                           /* Yes, we did. */

      dmmu_stats.loads_tlbhit++;

      dtlbtr = dtlbmr + 128;

      /* Test for page fault */

      if (cpu_state.sprs[SPR_SR] & SPR_SR_SM)

        {

          if ((write_access && !(*dtlbtr & SPR_DTLBTR_SWE)) ||

              (!write_access && !(*dtlbtr & SPR_DTLBTR_SRE)))

            /* otherwise exception DPF would be raised */

            return (0);

        }

      else

        {

          if ((write_access && !(*dtlbtr & SPR_DTLBTR_UWE)) ||

              (!write_access && !(*dtlbtr & SPR_DTLBTR_URE)))

            /* otherwise exception DPF would be raised */

            return (0);

        }

      if (through_dc)

        {

          /* Check if page is cache inhibited */

          data_ci = *dtlbtr & SPR_DTLBTR_CI;

        }

      return (*dtlbtr & SPR_DTLBTR_PPN) | (virtaddr &

                                           (dmmu->page_offset_mask));

    }

  return (0);

}

/* FIXME: Is this comment valid? */

/* First check if virtual address is covered by DTLB and if it is:

    - increment DTLB read hit stats,

    - set 'lru' at this way to dmmu->ustates - 1 and

      decrement 'lru' of other ways unless they have reached 0,

    - check page access attributes and invoke DMMU page fault exception

      handler if necessary

   and if not:

    - increment DTLB read miss stats

    - find lru way and entry and invoke DTLB miss exception handler

    - set 'lru' with dmmu->ustates - 1 and decrement 'lru' of other

      ways unless they have reached 0

*/

static void

dtlb_status (void *dat)

{

  struct dmmu *dmmu = dat;

  int set;

  int way;

  int end_set = dmmu->nsets;

  if (!(cpu_state.sprs[SPR_UPR] & SPR_UPR_DMP))

    {

      PRINTF ("DMMU not implemented. Set UPR[DMP].\n");

      return;

    }

  if (0 < end_set)

    PRINTF ("\nDMMU: ");

  /* Scan set(s) and way(s). */

  for (set = 0; set < end_set; set++)

    {

      for (way = 0; way < dmmu->nways; way++)

        {

          PRINTF ("%s\n", dump_spr (SPR_DTLBMR_BASE (way) + set,

                                    cpu_state.sprs[SPR_DTLBMR_BASE (way) +

                                                   set]));

          PRINTF ("%s\n",

                  dump_spr (SPR_DTLBTR_BASE (way) + set,

                            cpu_state.sprs[SPR_DTLBTR_BASE (way) + set]));

        }

    }

  if (0 < end_set)

    PRINTF ("\n");

}

/*---------------------------------------------------[ DMMU configuration ]---*/

/*---------------------------------------------------------------------------*/

/*!Enable or disable the DMMU

   Set the corresponding field in the UPR

   @param[in] val  The value to use

   @param[in] dat  The config data structure                                 */

/*---------------------------------------------------------------------------*/

static void

dmmu_enabled (union param_val val, void *dat)

{

  struct dmmu *dmmu = dat;

  if (val.int_val)

    {

      cpu_state.sprs[SPR_UPR] |= SPR_UPR_DMP;

    }

  else

    {

      cpu_state.sprs[SPR_UPR] &= ~SPR_UPR_DMP;

    }

  dmmu->enabled = val.int_val;

}       /* dmmu_enabled() */

/*---------------------------------------------------------------------------*/

/*!Set the number of DMMU sets

   Value must be a power of 2 <= 256. Ignore any other values with a

   warning. Set the corresponding DMMU configuration flags.

   @param[in] val  The value to use

   @param[in] dat  The config data structure                                 */

/*---------------------------------------------------------------------------*/

static void

dmmu_nsets (union param_val  val,

            void            *dat)

{

  struct dmmu *dmmu = dat;

  if (is_power2 (val.int_val) && val.int_val <= 128)

    {

      int  set_bits = log2_int (val.int_val);

      dmmu->nsets = val.int_val;

      cpu_state.sprs[SPR_DMMUCFGR] &= ~SPR_DMMUCFGR_NTS;

      cpu_state.sprs[SPR_DMMUCFGR] |= set_bits << SPR_DMMUCFGR_NTS_OFF;

    }

  else

    {

      fprintf (stderr, "Warning DMMU nsets not a power of 2 <= 128: ignored\n");

    }

}       /* dmmu_nsets() */

/*---------------------------------------------------------------------------*/

/*!Set the number of DMMU ways

   Value must be in the range 1-4. Ignore other values with a warning. Set the

   corresponding DMMU configuration flags.

   @param[in] val  The value to use

   @param[in] dat  The config data structure                                 */

/*---------------------------------------------------------------------------*/

static void

dmmu_nways (union param_val  val,

            void            *dat)

{

  struct dmmu *dmmu = dat;

  if (val.int_val >= 1 && val.int_val <= 4)

    {

      int  way_bits = val.int_val - 1;

      dmmu->nways = val.int_val;

      cpu_state.sprs[SPR_DMMUCFGR] &= ~SPR_DMMUCFGR_NTW;

      cpu_state.sprs[SPR_DMMUCFGR] |= way_bits << SPR_DMMUCFGR_NTW_OFF;

    }

  else

    {

      fprintf (stderr, "Warning DMMU nways not in range 1-4: ignored\n");

    }

}       /* dmmu_nways() */

/*---------------------------------------------------------------------------*/

/*!Set the DMMU page size

   Value must be a power of 2. Ignore other values with a warning

   @param[in] val  The value to use

   @param[in] dat  The config data structure                                 */

/*---------------------------------------------------------------------------*/

static void

dmmu_pagesize (union param_val  val,

               void            *dat)

{

  struct dmmu *dmmu = dat;

  if (is_power2 (val.int_val))

    {

      dmmu->pagesize = val.int_val;

    }

  else

    {

      fprintf (stderr, "Warning DMMU page size must be power of 2: ignored\n");

    }

}       /* dmmu_pagesize() */

/*---------------------------------------------------------------------------*/

/*!Set the DMMU entry size

   Value must be a power of 2. Ignore other values with a warning

   @param[in] val  The value to use

   @param[in] dat  The config data structure                                 */

/*---------------------------------------------------------------------------*/

static void

dmmu_entrysize (union param_val  val,

                void            *dat)

{

  struct dmmu *dmmu = dat;

  if (is_power2 (val.int_val))

    {

      dmmu->entrysize = val.int_val;

    }

  else

    {

      fprintf (stderr, "Warning DMMU entry size must be power of 2: ignored\n");

    }

}       /* dmmu_entrysize() */

/*---------------------------------------------------------------------------*/

/*!Set the number of DMMU usage states

   Value must be 2, 3 or 4. Ignore other values with a warning

   @param[in] val  The value to use

   @param[in] dat  The config data structure                                 */

/*---------------------------------------------------------------------------*/

static void

dmmu_ustates (union param_val  val,

              void            *dat)

{

  struct dmmu *dmmu = dat;

  if ((val.int_val >= 2) && (val.int_val <= 4))

    {

      dmmu->ustates = val.int_val;

    }

  else

    {

      fprintf (stderr, "Warning number of DMMU usage states must be 2, 3 or 4:"

               "ignored\n");

    }

}       /* dmmu_ustates() */

static void

dmmu_missdelay (union param_val val, void *dat)

{

  struct dmmu *dmmu = dat;

  dmmu->missdelay = val.int_val;

}

static void

dmmu_hitdelay (union param_val val, void *dat)

{

  struct dmmu *dmmu = dat;

  dmmu->hitdelay = val.int_val;

}

/*---------------------------------------------------------------------------*/

/*!Initialize a new DMMU configuration

   ALL parameters are set explicitly to default values. Corresponding SPR

   flags are set as appropriate.

   @return  The new memory configuration data structure                      */

/*---------------------------------------------------------------------------*/

static void *

dmmu_start_sec ()

{

  struct dmmu *dmmu;

  int          set_bits;

  int          way_bits;

  if (NULL == (dmmu = malloc (sizeof (struct dmmu))))

    {

      fprintf (stderr, "OOM\n");

      exit (1);

    }

  dmmu->enabled   = 0;

  dmmu->nsets     = 1;

  dmmu->nways     = 1;

  dmmu->pagesize  = 8192;

  dmmu->entrysize = 1;          /* Not currently used */

  dmmu->ustates   = 2;

  dmmu->hitdelay  = 1;

  dmmu->missdelay = 1;

  if (dmmu->enabled)

    {

      cpu_state.sprs[SPR_UPR] |= SPR_UPR_DMP;

    }

  else

    {

      cpu_state.sprs[SPR_UPR] &= ~SPR_UPR_DMP;

    }

  set_bits = log2_int (dmmu->nsets);

  cpu_state.sprs[SPR_DMMUCFGR] &= ~SPR_DMMUCFGR_NTS;

  cpu_state.sprs[SPR_DMMUCFGR] |= set_bits << SPR_DMMUCFGR_NTS_OFF;

  way_bits = dmmu->nways - 1;

  cpu_state.sprs[SPR_DMMUCFGR] &= ~SPR_DMMUCFGR_NTW;

  cpu_state.sprs[SPR_DMMUCFGR] |= way_bits << SPR_DMMUCFGR_NTW_OFF;

  dmmu_state = dmmu;

  return dmmu;

}       /* dmmu_start_sec() */

static void

dmmu_end_sec (void *dat)

{

  struct dmmu *dmmu = dat;

  /* Precalculate some values for use during address translation */

  dmmu->pagesize_log2 = log2_int (dmmu->pagesize);

  dmmu->page_offset_mask = dmmu->pagesize - 1;

  dmmu->page_mask = ~dmmu->page_offset_mask;

  dmmu->vpn_mask = ~((dmmu->pagesize * dmmu->nsets) - 1);

  dmmu->set_mask = dmmu->nsets - 1;

  dmmu->lru_reload = (dmmu->set_mask << 6) & SPR_DTLBMR_LRU;

  if (dmmu->enabled)

    {

      PRINTF ("Data MMU %dKB: %d ways, %d sets, entry size %d bytes\n",

              dmmu->nsets * dmmu->entrysize * dmmu->nways / 1024, dmmu->nways,

              dmmu->nsets, dmmu->entrysize);

      reg_sim_stat (dtlb_status, dmmu);

    }

}

void

reg_dmmu_sec (void)

{

  struct config_section *sec = reg_config_sec ("dmmu", dmmu_start_sec,

                                               dmmu_end_sec);

  reg_config_param (sec, "enabled",   PARAMT_INT, dmmu_enabled);

  reg_config_param (sec, "nsets",     PARAMT_INT, dmmu_nsets);

  reg_config_param (sec, "nways",     PARAMT_INT, dmmu_nways);

  reg_config_param (sec, "pagesize",  PARAMT_INT, dmmu_pagesize);

  reg_config_param (sec, "entrysize", PARAMT_INT, dmmu_entrysize);

  reg_config_param (sec, "ustates",   PARAMT_INT, dmmu_ustates);

  reg_config_param (sec, "hitdelay",  PARAMT_INT, dmmu_hitdelay);

  reg_config_param (sec, "missdelay", PARAMT_INT, dmmu_missdelay);

}