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/* dmmu.c -- Data MMU simulation

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

This file is part of 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 2 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, write to the Free Software

Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */

/* DMMU model (not functional yet, currently just copy of data cache). */

#include "dmmu.h"

#include "abstract.h"

#include "stats.h"

#include "sprs.h"

#include "except.h"

#include "sim-config.h"

extern int cont_run;

/* Data MMU */

inline unsigned long dmmu_simulate_tlb(unsigned long virtaddr, int write_access)

{

  int set, way = -1;

  int i;

  unsigned long tagaddr;

  unsigned long vpn, ppn;

  extern int mem_cycles;

  if (!(mfspr(SPR_SR) & SPR_SR_DME) || !testsprbits(SPR_UPR, SPR_UPR_DMP)) {

    data_ci = (virtaddr >= 0x80000000);

    return virtaddr;

  }

  /* Which set to check out? */

  set = (virtaddr / config.dmmu.pagesize) % config.dmmu.nsets;

  tagaddr = (virtaddr / config.dmmu.pagesize) / config.dmmu.nsets;

  vpn = virtaddr / (config.dmmu.pagesize * config.dmmu.nsets);

  /* Scan all ways and try to find a matching way. */

  for (i = 0; i < config.dmmu.nways; i++)

    if (((mfspr(SPR_DTLBMR_BASE(i) + set) / (config.dmmu.pagesize * config.dmmu.nsets)) == vpn) &&

        testsprbits(SPR_DTLBMR_BASE(i) + set, SPR_DTLBMR_V))

      way = i;

   /* Did we find our tlb entry? */

  if (way >= 0) { /* Yes, we did. */

    dmmu_stats.loads_tlbhit++;

    debug(5, "DTLB hit (virtaddr=%x).\n", virtaddr);

    /* Test for page fault */

    if (mfspr (SPR_SR) & SPR_SR_SM) {

      if ( write_access && !(mfspr (SPR_DTLBTR_BASE(way) + set) & SPR_DTLBTR_SWE)

       || !write_access && !(mfspr (SPR_DTLBTR_BASE(way) + set) & SPR_DTLBTR_SRE))

        except_handle(EXCEPT_DPF, virtaddr);

    } else {

      if ( write_access && !(mfspr (SPR_DTLBTR_BASE(way) + set) & SPR_DTLBTR_UWE)

       || !write_access && !(mfspr (SPR_DTLBTR_BASE(way) + set) & SPR_DTLBTR_URE))

        except_handle(EXCEPT_DPF, virtaddr);

    }

    /* Set LRUs */

    for (i = 0; i < config.dmmu.nways; i++)

      if (testsprbits(SPR_DTLBMR_BASE(i) + set, SPR_DTLBMR_LRU))

        setsprbits(SPR_DTLBMR_BASE(i) + set, SPR_DTLBMR_LRU, getsprbits(SPR_DTLBMR_BASE(i) + set, SPR_DTLBMR_LRU) - 1);

    setsprbits(SPR_DTLBMR_BASE(way) + set, SPR_DTLBMR_LRU, config.dmmu.ustates - 1);

    /* Check if page is cache inhibited */

    data_ci = (mfspr(SPR_DTLBTR_BASE(way) + set) & SPR_DTLBTR_CI) == SPR_DTLBTR_CI;

    mem_cycles += config.dmmu.hitdelay;

    ppn = mfspr(SPR_DTLBTR_BASE(way) + set) / config.dmmu.pagesize;

    return (ppn * config.dmmu.pagesize) + (virtaddr % config.dmmu.pagesize);

  }

  else {  /* No, we didn't. */

    int minlru = config.dmmu.ustates - 1;

    int minway = 0;

    dmmu_stats.loads_tlbmiss++;

#if 0

    for (i = 0; i < config.dmmu.nways; i++)

      if (getsprbits(SPR_DTLBMR_BASE(i) + set, SPR_DTLBMR_LRU) < minlru)

        minway = i;

    setsprbits(SPR_DTLBMR_BASE(minway) + set, SPR_DTLBMR_VPN, vpn);

    for (i = 0; i < config.dmmu.nways; i++)

      if (getsprbits(SPR_DTLBMR_BASE(i) + set, SPR_DTLBMR_LRU))

        setsprbits(SPR_DTLBMR_BASE(i) + set, SPR_DTLBMR_LRU, getsprbits(SPR_DTLBMR_BASE(i) + set, SPR_DTLBMR_LRU) - 1);

    setsprbits(SPR_DTLBMR_BASE(minway) + set, SPR_DTLBMR_LRU, config.dmmu.ustates - 1);

    setsprbits(SPR_DTLBTR_BASE(minway) + set, SPR_DTLBTR_PPN, vpn); /* 1 to 1 */

    setsprbits(SPR_DTLBMR_BASE(minway) + set, SPR_DTLBMR_V, 1);

#endif

    except_handle(EXCEPT_DTLBMISS, virtaddr);

    /* if tlb refill implemented in HW */

    /* return getsprbits(SPR_DTLBTR_BASE(minway) + set, SPR_DTLBTR_PPN) * config.dmmu.pagesize + (virtaddr % config.dmmu.pagesize); */

    mem_cycles += config.dmmu.missdelay;

    return 0;

  }

}

unsigned long dmmu_translate(unsigned long virtaddr, int write_access)

{

  unsigned long phyaddr = dmmu_simulate_tlb(virtaddr, write_access);

/*  printf("DMMU translate(%x) = %x\n", virtaddr, phyaddr);*/

  return phyaddr;

}

void dtlb_info()

{

  if (!testsprbits(SPR_UPR, SPR_UPR_DMP)) {

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

    return;

  }

  printf("Data MMU %dKB: ", config.dmmu.nsets * config.dmmu.entrysize * config.dmmu.nways / 1024);

  printf("%d ways, %d sets, entry size %d bytes\n", config.dmmu.nways, config.dmmu.nsets, config.dmmu.entrysize);

}

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

    - increment DTLB read hit stats,

    - set 'lru' at this way to config.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 config.dmmu.ustates - 1 and decrement 'lru' of other

      ways unless they have reached 0

*/

void dtlb_status(int start_set)

{

  int set;

  int way;

  int end_set = config.dmmu.nsets;

  if (!testsprbits(SPR_UPR, SPR_UPR_DMP)) {

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

    return;

  }

  if ((start_set >= 0) && (start_set < end_set))

    end_set = start_set + 1;

  else

    start_set = 0;

  if (start_set < end_set) printf("\nDMMU: ");

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

  for (set = start_set; set < end_set; set++) {

    printf("\nSet %x: ", set);

    for (way = 0; way < config.dmmu.nways; way++) {

      printf("  way %d: ", way);

      printf("vpn=%x ", getsprbits(SPR_DTLBMR_BASE(way) + set, SPR_DTLBMR_VPN));

      printf("lru=%x ", getsprbits(SPR_DTLBMR_BASE(way) + set, SPR_DTLBMR_LRU));

      printf("pl1=%x ", getsprbits(SPR_DTLBMR_BASE(way) + set, SPR_DTLBMR_PL1));

      printf("v=%x ", getsprbits(SPR_DTLBMR_BASE(way) + set, SPR_DTLBMR_V));

      printf("a=%x ", getsprbits(SPR_DTLBTR_BASE(way) + set, SPR_DTLBTR_A));

      printf("d=%x ", getsprbits(SPR_DTLBTR_BASE(way) + set, SPR_DTLBTR_D));

      printf("ure=%x ", getsprbits(SPR_DTLBTR_BASE(way) + set, SPR_DTLBTR_URE));

      printf("uwe=%x ", getsprbits(SPR_DTLBTR_BASE(way) + set, SPR_DTLBTR_UWE));

      printf("sre=%x ", getsprbits(SPR_DTLBTR_BASE(way) + set, SPR_DTLBTR_SRE));

      printf("swe=%x ", getsprbits(SPR_DTLBTR_BASE(way) + set, SPR_DTLBTR_SWE));

      printf("ppn=%x ", getsprbits(SPR_DTLBTR_BASE(way) + set, SPR_DTLBTR_PPN));

    }

  }

  if (start_set < end_set) printf("\n");

}