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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"
#include "debug.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. */
    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=%lx ", getsprbits(SPR_ITLBMR_BASE(way) + set, SPR_ITLBMR_VPN));
      PRINTF("lru=%lx ", getsprbits(SPR_ITLBMR_BASE(way) + set, SPR_ITLBMR_LRU));
      PRINTF("pl1=%lx ", getsprbits(SPR_ITLBMR_BASE(way) + set, SPR_ITLBMR_PL1));
      PRINTF("v=%lx ", getsprbits(SPR_ITLBMR_BASE(way) + set, SPR_ITLBMR_V));
 
      PRINTF("a=%lx ", getsprbits(SPR_ITLBTR_BASE(way) + set, SPR_ITLBTR_A));
      PRINTF("d=%lx ", getsprbits(SPR_ITLBTR_BASE(way) + set, SPR_ITLBTR_D));
      PRINTF("uxe=%lx ", getsprbits(SPR_ITLBTR_BASE(way) + set, SPR_ITLBTR_UXE));
      PRINTF("sxe=%lx ", getsprbits(SPR_ITLBTR_BASE(way) + set, SPR_ITLBTR_SXE));
      PRINTF("ppn=%lx ", getsprbits(SPR_ITLBTR_BASE(way) + set, SPR_ITLBTR_PPN));
    }
  }
  if (start_set < end_set) PRINTF("\n");
}