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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"
#include "debug.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;
 
  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.nsets - 1);
 
    /* Check if page is cache inhibited */
    data_ci = (mfspr(SPR_DTLBTR_BASE(way) + set) & SPR_DTLBTR_CI) == SPR_DTLBTR_CI;
 
    runtime.sim.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. */
    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); */
    runtime.sim.mem_cycles += config.dmmu.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 
 *
 *       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)
 */
unsigned long peek_into_dtlb(unsigned long virtaddr, int write_access,
			    int through_dc)
{
  int set, way = -1;
  int i;
  unsigned long tagaddr;
  unsigned long vpn, ppn;
 
  if (!(mfspr(SPR_SR) & SPR_SR_DME) || !testsprbits(SPR_UPR, SPR_UPR_DMP)) {
    if (through_dc)
      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))
 
	/* otherwise exception DPF would be raised */
	return(0);
    } else {
      if ( write_access && !(mfspr (SPR_DTLBTR_BASE(way) + set) & SPR_DTLBTR_UWE)
       || !write_access && !(mfspr (SPR_DTLBTR_BASE(way) + set) & SPR_DTLBTR_URE))
 
	/* otherwise exception DPF would be raised */	
	return(0);
    }
 
    if (through_dc) {
      /* Check if page is cache inhibited */
      data_ci = (mfspr(SPR_DTLBTR_BASE(way) + set) & SPR_DTLBTR_CI) == SPR_DTLBTR_CI;
    }
 
    ppn = mfspr(SPR_DTLBTR_BASE(way) + set) / config.dmmu.pagesize;
    return (ppn * config.dmmu.pagesize) + (virtaddr % config.dmmu.pagesize);
  }
  else {  /* No, we didn't. */
    return(0);
  }
 
  PRINTF("ERR, should never have happened\n");
  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=%lx ", getsprbits(SPR_DTLBMR_BASE(way) + set, SPR_DTLBMR_VPN));
      PRINTF("lru=%lx ", getsprbits(SPR_DTLBMR_BASE(way) + set, SPR_DTLBMR_LRU));
      PRINTF("pl1=%lx ", getsprbits(SPR_DTLBMR_BASE(way) + set, SPR_DTLBMR_PL1));
      PRINTF("v=%lx ", getsprbits(SPR_DTLBMR_BASE(way) + set, SPR_DTLBMR_V));
 
      PRINTF("a=%lx ", getsprbits(SPR_DTLBTR_BASE(way) + set, SPR_DTLBTR_A));
      PRINTF("d=%lx ", getsprbits(SPR_DTLBTR_BASE(way) + set, SPR_DTLBTR_D));
      PRINTF("ure=%lx ", getsprbits(SPR_DTLBTR_BASE(way) + set, SPR_DTLBTR_URE));
      PRINTF("uwe=%lx ", getsprbits(SPR_DTLBTR_BASE(way) + set, SPR_DTLBTR_UWE));
      PRINTF("sre=%lx ", getsprbits(SPR_DTLBTR_BASE(way) + set, SPR_DTLBTR_SRE));
      PRINTF("swe=%lx ", getsprbits(SPR_DTLBTR_BASE(way) + set, SPR_DTLBTR_SWE));
      PRINTF("ppn=%lx ", getsprbits(SPR_DTLBTR_BASE(way) + set, SPR_DTLBTR_PPN));
    }
  }
  if (start_set < end_set) PRINTF("\n");
}