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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, perfectly functional. */

#include "config.h"

#ifdef HAVE_INTTYPES_H

#include <inttypes.h>

#endif

#include "port.h"

#include "arch.h"

#include "dmmu.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(dmmu);

struct dmmu *dmmu_state;

/* Data MMU */

static inline 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;

    TRACE("DTLB hit (virtaddr=%"PRIxADDR") at %lli.\n", virtaddr,

          runtime.sim.cycles);

    /* 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);

    }

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

          (*dtlbtr & SPR_DTLBTR_PPN) | (virtaddr & (dmmu->page_offset_mask)));

    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

  TRACE("DTLB miss (virtaddr=%"PRIxADDR") at %lli.\n", virtaddr,

        runtime.sim.cycles);

  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;

    TRACE("DTLB hit (virtaddr=%"PRIxADDR") at %lli.\n", virtaddr,

          runtime.sim.cycles);

    /* 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 ]---*/

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;

}

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

{

  struct dmmu *dmmu = dat;

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

    dmmu->nsets = val.int_val;

    cpu_state.sprs[SPR_DMMUCFGR] &= ~SPR_DMMUCFGR_NTS;

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

  } else

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

}

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

{

  struct dmmu *dmmu = dat;

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

    dmmu->nways = val.int_val;

    cpu_state.sprs[SPR_DMMUCFGR] &= ~SPR_DMMUCFGR_NTW;

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

  }

  else

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

}

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

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

}

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

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

}

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

    CONFIG_ERROR("invalid USTATE.");

}

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;

}

static void *dmmu_start_sec(void)

{

  struct dmmu *dmmu;

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

    fprintf(stderr, "OOM\n");

    exit(1);

  }

  dmmu->enabled = 0;

  dmmu->hitdelay = 1;

  dmmu->missdelay = 1;

  dmmu->pagesize = 8192;

  /* FIXME: Something sane */

  dmmu->entrysize = 0;

  dmmu_state = dmmu;

  return dmmu;

}

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, "missdelay", paramt_int, dmmu_missdelay);

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

}