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/* immu.c -- Instruction 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. */

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

#include "immu.h"

#include "abstract.h"

#include "stats.h"

#include "sprs.h"

#include "except.h"

#include "sim-config.h"

extern int cont_run;

/* Insn MMU */

static inline unsigned long immu_simulate_tlb(unsigned long virtaddr)

{

  int set, way = -1;

  int i;

  unsigned long tagaddr;

  unsigned long vpn, ppn;

  if (!(mfspr(SPR_SR) & SPR_SR_IME) || !(testsprbits(SPR_UPR, SPR_UPR_IMP))) {

    insn_ci = (virtaddr >= 0x80000000);

    return virtaddr;

  }

  /* Which set to check out? */

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

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

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

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

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

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

        testsprbits(SPR_ITLBMR_BASE(i) + set, SPR_ITLBMR_V))

      way = i;

  /* Did we find our tlb entry? */

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

    immu_stats.fetch_tlbhit++;

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

    /* Test for page fault */

    if (mfspr (SPR_SR) & SPR_SR_SM) {

      if (!(mfspr (SPR_ITLBTR_BASE(way) + set) & SPR_ITLBTR_SXE))

        except_handle(EXCEPT_IPF, virtaddr);

    } else {

      if (!(mfspr (SPR_ITLBTR_BASE(way) + set) & SPR_ITLBTR_UXE))

        except_handle(EXCEPT_IPF, virtaddr);

    }

    /* Set LRUs */

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

      if (testsprbits(SPR_ITLBMR_BASE(i) + set, SPR_ITLBMR_LRU))

        setsprbits(SPR_ITLBMR_BASE(i) + set, SPR_ITLBMR_LRU, getsprbits(SPR_ITLBMR_BASE(i) + set, SPR_ITLBMR_LRU) - 1);

    setsprbits(SPR_ITLBMR_BASE(way) + set, SPR_ITLBMR_LRU, config.immu.nsets - 1);

    /* Check if page is cache inhibited */

    insn_ci = (mfspr(SPR_ITLBTR_BASE(way) + set) & SPR_ITLBTR_CI) == SPR_ITLBTR_CI;

    runtime.sim.mem_cycles += config.immu.hitdelay;

    ppn = mfspr(SPR_ITLBTR_BASE(way) + set) / config.immu.pagesize;

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

  }

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

    int minlru = config.immu.nsets - 1;

    int minway = 0;

    immu_stats.fetch_tlbmiss++;

#if 0

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

      if (getsprbits(SPR_ITLBMR_BASE(i) + set, SPR_ITLBMR_LRU) < minlru)

        minway = i;

    setsprbits(SPR_ITLBMR_BASE(minway) + set, SPR_ITLBMR_VPN, vpn);

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

      if (testsprbits(SPR_ITLBMR_BASE(i) + set, SPR_ITLBMR_LRU))

        setsprbits(SPR_ITLBMR_BASE(i) + set, SPR_ITLBMR_LRU, getsprbits(SPR_ITLBMR_BASE(i) + set, SPR_ITLBMR_LRU) - 1);

    setsprbits(SPR_ITLBMR_BASE(minway) + set, SPR_ITLBMR_LRU, config.immu.ustates - 1);

    setsprbits(SPR_ITLBTR_BASE(minway) + set, SPR_ITLBTR_PPN, vpn); /* 1 to 1 */

    setsprbits(SPR_ITLBMR_BASE(minway) + set, SPR_ITLBMR_V, 1);

#endif

    except_handle(EXCEPT_ITLBMISS, virtaddr);

    /* if tlb refill implemented in HW */

    /* return getsprbits(SPR_ITLBTR_BASE(minway) + set, SPR_ITLBTR_PPN) * config.immu.pagesize + (virtaddr % config.immu.pagesize); */

    runtime.sim.mem_cycles += config.immu.missdelay;

    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

 *

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

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

 *                   PA === EA)

 */

unsigned long peek_into_itlb(unsigned long virtaddr)

{

  int set, way = -1;

  int i;

  unsigned long tagaddr;

  unsigned long vpn, ppn;

  if (!(mfspr(SPR_SR) & SPR_SR_IME) || !(testsprbits(SPR_UPR, SPR_UPR_IMP))) {

     return(virtaddr);

  }

  /* Which set to check out? */

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

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

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

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

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

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

        testsprbits(SPR_ITLBMR_BASE(i) + set, SPR_ITLBMR_V))

      way = i;

  /* Did we find our tlb entry? */

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

    /* Test for page fault */

    if (mfspr (SPR_SR) & SPR_SR_SM) {

      if (!(mfspr (SPR_ITLBTR_BASE(way) + set) & SPR_ITLBTR_SXE)) {

        /* no luck, giving up */

        return(0);

      }

    } else {

      if (!(mfspr (SPR_ITLBTR_BASE(way) + set) & SPR_ITLBTR_UXE)) {

        /* no luck, giving up */

        return(0);

      }

    }

    ppn = mfspr(SPR_ITLBTR_BASE(way) + set) / config.immu.pagesize;

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

  }

  else {

    return(0);

  }

  PRINTF("ERR, should never have happened\n");

  return(0);

}

unsigned long immu_translate(unsigned long virtaddr)

{

  unsigned long phyaddr = immu_simulate_tlb(virtaddr);

/*  PRINTF("IMMU translate(%x) = %x\n", virtaddr, phyaddr);*/

  return phyaddr;

}

void itlb_info()

{

  if (!testsprbits(SPR_UPR, SPR_UPR_IMP)) {

    PRINTF("IMMU not implemented. Set UPR[IMP].\n");

    return;

  }

  PRINTF("Insn MMU %dKB: ", config.immu.nsets * config.immu.entrysize * config.immu.nways / 1024);

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

}

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

    - increment ITLB read hit stats,

    - set 'lru' at this way to config.immu.ustates - 1 and

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

    - check page access attributes and invoke IMMU page fault exception

      handler if necessary

   and if not:

    - increment ITLB read miss stats

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

    - set 'lru' with config.immu.ustates - 1 and decrement 'lru' of other

      ways unless they have reached 0

*/

void itlb_status(int start_set)

{

  int set;

  int way;

  int end_set = config.immu.nsets;

  if (!testsprbits(SPR_UPR, SPR_UPR_IMP)) {

    PRINTF("IMMU not implemented. Set UPR[IMP].\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("\nIMMU: ");

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

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

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

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

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

      PRINTF("vpn=%x ", getsprbits(SPR_ITLBMR_BASE(way) + set, SPR_ITLBMR_VPN));

      PRINTF("lru=%x ", getsprbits(SPR_ITLBMR_BASE(way) + set, SPR_ITLBMR_LRU));

      PRINTF("pl1=%x ", getsprbits(SPR_ITLBMR_BASE(way) + set, SPR_ITLBMR_PL1));

      PRINTF("v=%x ", getsprbits(SPR_ITLBMR_BASE(way) + set, SPR_ITLBMR_V));

      PRINTF("a=%x ", getsprbits(SPR_ITLBTR_BASE(way) + set, SPR_ITLBTR_A));

      PRINTF("d=%x ", getsprbits(SPR_ITLBTR_BASE(way) + set, SPR_ITLBTR_D));

      PRINTF("uxe=%x ", getsprbits(SPR_ITLBTR_BASE(way) + set, SPR_ITLBTR_UXE));

      PRINTF("sxe=%x ", getsprbits(SPR_ITLBTR_BASE(way) + set, SPR_ITLBTR_SXE));

      PRINTF("ppn=%x ", getsprbits(SPR_ITLBTR_BASE(way) + set, SPR_ITLBTR_PPN));

    }

  }

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

}