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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, perfectly functional. */

#include "config.h"

#ifdef HAVE_INTTYPES_H

#include <inttypes.h>

#endif

#include "port.h"

#include "arch.h"

#include "immu.h"

#include "abstract.h"

#include "opcode/or32.h"

#include "spr_defs.h"

#include "execute.h"

#include "stats.h"

#include "sprs.h"

#include "except.h"

#include "sim-config.h"

#include "debug.h"

#include "misc.h"

DEFAULT_DEBUG_CHANNEL(immu);

struct immu *immu_state;

/* Insn MMU */

static inline uorreg_t *immu_find_tlbmr(oraddr_t virtaddr,

                                        uorreg_t **itlbmr_lru,

                                        struct immu *immu)

{

  int set;

  int i;

  oraddr_t vpn;

  uorreg_t *itlbmr;

  /* Which set to check out? */

  set = IADDR_PAGE(virtaddr) >> immu->pagesize_log2;

  set &= immu->set_mask;

  vpn = virtaddr & immu->vpn_mask;

  itlbmr = &cpu_state.sprs[SPR_ITLBMR_BASE(0) + set];

  *itlbmr_lru = itlbmr;

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

  /* FIXME: Should this be reversed? */

  for(i = immu->nways; i; i--, itlbmr += (128 * 2)) {

    if(((*itlbmr & immu->vpn_mask) == vpn) && (*itlbmr & SPR_ITLBMR_V))

      return itlbmr;

  }

  return NULL;

}

oraddr_t immu_translate(oraddr_t virtaddr)

{

  int i;

  uorreg_t *itlbmr;

  uorreg_t *itlbtr;

  uorreg_t *itlbmr_lru;

  struct immu *immu = immu_state;

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

      !(cpu_state.sprs[SPR_UPR] & SPR_UPR_IMP)) {

    insn_ci = (virtaddr >= 0x80000000);

    return virtaddr;

  }

  itlbmr = immu_find_tlbmr(virtaddr, &itlbmr_lru, immu);

  /* Did we find our tlb entry? */

  if(itlbmr) { /* Yes, we did. */

    immu_stats.fetch_tlbhit++;

    TRACE("ITLB hit (virtaddr=%"PRIxADDR").\n", virtaddr);

    itlbtr = itlbmr + 128;

    /* Set LRUs */

    for(i = 0; i < immu->nways; i++, itlbmr_lru += (128 * 2)) {

      if(*itlbmr_lru & SPR_ITLBMR_LRU)

        *itlbmr_lru = (*itlbmr_lru & ~SPR_ITLBMR_LRU) |

                                        ((*itlbmr_lru & SPR_ITLBMR_LRU) - 0x40);

    }

    /* This is not necessary `*itlbmr &= ~SPR_ITLBMR_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 */

    *itlbmr |= immu->lru_reload;

    /* Check if page is cache inhibited */

    insn_ci = *itlbtr & SPR_ITLBTR_CI;

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

    /* Test for page fault */

    if (cpu_state.sprs[SPR_SR] & SPR_SR_SM) {

      if (!(*itlbtr & SPR_ITLBTR_SXE))

        except_handle(EXCEPT_IPF, virtaddr);

    } else {

      if (!(*itlbtr & SPR_ITLBTR_UXE))

        except_handle(EXCEPT_IPF, virtaddr);

    }

    TRACE("Returning physical address %"PRIxADDR"\n",

          (*itlbtr & SPR_ITLBTR_PPN) | (virtaddr & immu->page_offset_mask));

    return (*itlbtr & SPR_ITLBTR_PPN) | (virtaddr & immu->page_offset_mask);

  }

  /* No, we didn't. */

  immu_stats.fetch_tlbmiss++;

#if 0

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

    if (((cpu_state.sprs[SPR_ITLBMR_BASE(i) + set] & SPR_ITLBMR_LRU) >> 6) < minlru)

      minway = i;

  cpu_state.sprs[SPR_ITLBMR_BASE(minway) + set] &= ~SPR_ITLBMR_VPN;

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

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

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

    if (lru & SPR_ITLBMR_LRU) {

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

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

    }

  }

  cpu_state.sprs[SPR_ITLBMR_BASE(way) + set] &= ~SPR_ITLBMR_LRU;

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

  /* 1 to 1 mapping */

  cpu_state.sprs[SPR_ITLBTR_BASE(minway) + set] &= ~SPR_ITLBTR_PPN;

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

  cpu_state.sprs[SPR_ITLBMR_BASE(minway) + set] |= SPR_ITLBMR_V;

#endif

  /* if tlb refill implemented in HW */

  /* return ((cpu_state.sprs[SPR_ITLBTR_BASE(minway) + set] & SPR_ITLBTR_PPN) >> 12) * immu->pagesize + (virtaddr % immu->pagesize); */

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

  except_handle(EXCEPT_ITLBMISS, 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

 *

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

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

 *                   PA === EA)

 */

oraddr_t peek_into_itlb(oraddr_t virtaddr)

{

  uorreg_t *itlbmr;

  uorreg_t *itlbtr;

  uorreg_t *itlbmr_lru;

  struct immu *immu = immu_state;

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

      !(cpu_state.sprs[SPR_UPR] & SPR_UPR_IMP)) {

     return(virtaddr);

  }

  itlbmr = immu_find_tlbmr(virtaddr, &itlbmr_lru, immu);

  /* Did we find our tlb entry? */

  if(itlbmr) { /* Yes, we did. */

    itlbtr = itlbmr + 128;

    /* Test for page fault */

    if (cpu_state.sprs[SPR_SR] & SPR_SR_SM) {

      if (!(*itlbtr & SPR_ITLBTR_SXE)) {

        /* no luck, giving up */

        return(0);

      }

    } else {

      if (!(*itlbtr & SPR_ITLBTR_UXE)) {

        /* no luck, giving up */

        return(0);

      }

    }

    return (*itlbtr & SPR_ITLBTR_PPN) | (virtaddr & immu->page_offset_mask);

  }

  return(0);

}

/* FIXME: Check validity */

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

    - increment ITLB read hit stats,

    - set 'lru' at this way to 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 immu->ustates - 1 and decrement 'lru' of other

      ways unless they have reached 0

*/

static void itlb_status(void *dat)

{

  struct immu *immu = dat;

  int set;

  int way;

  int end_set = immu->nsets;

  if (!(cpu_state.sprs[SPR_UPR] & SPR_UPR_IMP)) {

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

    return;

  }

  if (0 < end_set) PRINTF("\nIMMU: ");

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

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

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

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

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

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

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

    }

  }

  if (0 < end_set) PRINTF("\n");

}

/*---------------------------------------------------[ IMMU configuration ]---*/

static void immu_enabled(union param_val val, void *dat)

{

  struct immu *immu = dat;

  if(val.int_val)

    cpu_state.sprs[SPR_UPR] |= SPR_UPR_IMP;

  else

    cpu_state.sprs[SPR_UPR] &= ~SPR_UPR_IMP;

  immu->enabled = val.int_val;

}

static void immu_nsets(union param_val val, void *dat)

{

  struct immu *immu = dat;

  if (is_power2(val.int_val) && val.int_val <= 256) {

    immu->nsets = val.int_val;

    cpu_state.sprs[SPR_IMMUCFGR] &= ~SPR_IMMUCFGR_NTS;

    cpu_state.sprs[SPR_IMMUCFGR] |= log2_int(val.int_val) << 3;

  }

  else

    CONFIG_ERROR("value of power of two and lower or equal than 256 expected.");

}

static void immu_nways(union param_val val, void *dat)

{

  struct immu *immu = dat;

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

    immu->nways = val.int_val;

    cpu_state.sprs[SPR_IMMUCFGR] &= ~SPR_IMMUCFGR_NTW;

    cpu_state.sprs[SPR_IMMUCFGR] |= val.int_val - 1;

  }

  else

    CONFIG_ERROR("value 1, 2, 3 or 4 expected.");

}

static void immu_pagesize(union param_val val, void *dat)

{

  struct immu *immu = dat;

  if (is_power2(val.int_val))

    immu->pagesize = val.int_val;

  else

    CONFIG_ERROR("value of power of two expected.");

}

static void immu_entrysize(union param_val val, void *dat)

{

  struct immu *immu = dat;

  if (is_power2(val.int_val))

    immu->entrysize = val.int_val;

  else

    CONFIG_ERROR("value of power of two expected.");

}

static void immu_ustates(union param_val val, void *dat)

{

  struct immu *immu = dat;

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

    immu->ustates = val.int_val;

  else

    CONFIG_ERROR("invalid USTATE.");

}

static void immu_missdelay(union param_val val, void *dat)

{

  struct immu *immu = dat;

  immu->missdelay = val.int_val;

}

static void immu_hitdelay(union param_val val, void *dat)

{

  struct immu *immu = dat;

  immu->hitdelay = val.int_val;

}

static void *immu_start_sec(void)

{

  struct immu *immu;

  if(!(immu = malloc(sizeof(struct immu)))) {

    fprintf(stderr, "OOM\n");

    exit(1);

  }

  immu->enabled = 0;

  immu->hitdelay = 1;

  immu->missdelay = 1;

  immu->pagesize = 8192;

  /* FIXME: Something sane */

  immu->entrysize = 0;

  immu_state = immu;

  return immu;

}

static void immu_end_sec(void *dat)

{

  struct immu *immu = dat;

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

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

  immu->page_offset_mask = immu->pagesize - 1;

  immu->page_mask = ~immu->page_offset_mask;

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

  immu->set_mask = immu->nsets - 1;

  immu->lru_reload = (immu->set_mask << 6) & SPR_ITLBMR_LRU;

  if(immu->enabled) {

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

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

           immu->nsets, immu->entrysize);

    reg_sim_stat(itlb_status, immu);

  }

}

void reg_immu_sec(void)

{

  struct config_section *sec = reg_config_sec("immu", immu_start_sec,

                                              immu_end_sec);

  reg_config_param(sec, "enabled", paramt_int, immu_enabled);

  reg_config_param(sec, "nsets", paramt_int, immu_nsets);

  reg_config_param(sec, "nways", paramt_int, immu_nways);

  reg_config_param(sec, "pagesize", paramt_int, immu_pagesize);

  reg_config_param(sec, "entrysize", paramt_int, immu_entrysize);

  reg_config_param(sec, "ustates", paramt_int, immu_ustates);

  reg_config_param(sec, "missdelay", paramt_int, immu_missdelay);

  reg_config_param(sec, "hitdelay", paramt_int, immu_hitdelay);

}