arch/powerpc/mm/44x_mmu.c

   1 /*
   2  * Modifications by Matt Porter (mporter@mvista.com) to support
   3  * PPC44x Book E processors.
   4  *
   5  * This file contains the routines for initializing the MMU
   6  * on the 4xx series of chips.
   7  *  -- paulus
   8  *
   9  *  Derived from arch/ppc/mm/init.c:
  10  *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
  11  *
  12  *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
  13  *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
  14  *    Copyright (C) 1996 Paul Mackerras
  15  *  Amiga/APUS changes by Jesper Skov (jskov@cygnus.co.uk).
  16  *
  17  *  Derived from "arch/i386/mm/init.c"
  18  *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
  19  *
  20  *  This program is free software; you can redistribute it and/or
  21  *  modify it under the terms of the GNU General Public License
  22  *  as published by the Free Software Foundation; either version
  23  *  2 of the License, or (at your option) any later version.
  24  *
  25  */
  26
  27 #include <linux/signal.h>
  28 #include <linux/sched.h>
  29 #include <linux/kernel.h>
  30 #include <linux/errno.h>
  31 #include <linux/string.h>
  32 #include <linux/types.h>
  33 #include <linux/ptrace.h>
  34 #include <linux/mman.h>
  35 #include <linux/mm.h>
  36 #include <linux/swap.h>
  37 #include <linux/stddef.h>
  38 #include <linux/vmalloc.h>
  39 #include <linux/init.h>
  40 #include <linux/delay.h>
  41 #include <linux/highmem.h>
  42
  43 #include <asm/pgalloc.h>
  44 #include <asm/prom.h>
  45 #include <asm/io.h>
  46 #include <asm/mmu_context.h>
  47 #include <asm/pgtable.h>
  48 #include <asm/mmu.h>
  49 #include <asm/uaccess.h>
  50 #include <asm/smp.h>
  51 #include <asm/bootx.h>
  52 #include <asm/machdep.h>
  53 #include <asm/setup.h>
  54
  55 #include "mmu_decl.h"
  56
  57 extern char etext[], _stext[];
  58
  59 /* Used by the 44x TLB replacement exception handler.
  60  * Just needed it declared someplace.
  61  */
  62 unsigned int tlb_44x_index = 0;
  63 unsigned int tlb_44x_hwater = 62;
  64
  65 /*
  66  * "Pins" a 256MB TLB entry in AS0 for kernel lowmem
  67  */
  68 static void __init
  69 ppc44x_pin_tlb(int slot, unsigned int virt, unsigned int phys)
  70 {
  71         unsigned long attrib = 0;
  72
  73         __asm__ __volatile__("\
  74         clrrwi  %2,%2,10\n\
  75         ori     %2,%2,%4\n\
  76         clrrwi  %1,%1,10\n\
  77         li      %0,0\n\
  78         ori     %0,%0,%5\n\
  79         tlbwe   %2,%3,%6\n\
  80         tlbwe   %1,%3,%7\n\
  81         tlbwe   %0,%3,%8"
  82         :
  83         : "r" (attrib), "r" (phys), "r" (virt), "r" (slot),
  84           "i" (PPC44x_TLB_VALID | PPC44x_TLB_256M),
  85           "i" (PPC44x_TLB_SW | PPC44x_TLB_SR | PPC44x_TLB_SX | PPC44x_TLB_G),
  86           "i" (PPC44x_TLB_PAGEID),
  87           "i" (PPC44x_TLB_XLAT),
  88           "i" (PPC44x_TLB_ATTRIB));
  89 }
  90
  91 /*
  92  * MMU_init_hw does the chip-specific initialization of the MMU hardware.
  93  */
  94 void __init MMU_init_hw(void)
  95 {
  96         flush_instruction_cache();
  97 }
  98
  99 unsigned long __init mmu_mapin_ram(void)
 100 {
 101         unsigned int pinned_tlbs = 1;
 102         int i;
 103
 104         /* Determine number of entries necessary to cover lowmem */
 105         pinned_tlbs = (unsigned int)
 106                 (_ALIGN(total_lowmem, PPC_PIN_SIZE) >> PPC44x_PIN_SHIFT);
 107
 108         /* Write upper watermark to save location */
 109         tlb_44x_hwater = PPC44x_LOW_SLOT - pinned_tlbs;
 110
 111         /* If necessary, set additional pinned TLBs */
 112         if (pinned_tlbs > 1)
 113                 for (i = (PPC44x_LOW_SLOT-(pinned_tlbs-1)); i < PPC44x_LOW_SLOT; i++) {
 114                         unsigned int phys_addr = (PPC44x_LOW_SLOT-i) * PPC_PIN_SIZE;
 115                         ppc44x_pin_tlb(i, phys_addr+PAGE_OFFSET, phys_addr);
 116                 }
 117
 118         return total_lowmem;
 119 }