linux/arch/powerpc/mm/init_32.c
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   1/*
   2 *  PowerPC version
   3 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
   4 *
   5 *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
   6 *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
   7 *    Copyright (C) 1996 Paul Mackerras
   8 *  PPC44x/36-bit changes by Matt Porter (mporter@mvista.com)
   9 *
  10 *  Derived from "arch/i386/mm/init.c"
  11 *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
  12 *
  13 *  This program is free software; you can redistribute it and/or
  14 *  modify it under the terms of the GNU General Public License
  15 *  as published by the Free Software Foundation; either version
  16 *  2 of the License, or (at your option) any later version.
  17 *
  18 */
  19
  20#include <linux/module.h>
  21#include <linux/sched.h>
  22#include <linux/kernel.h>
  23#include <linux/errno.h>
  24#include <linux/string.h>
  25#include <linux/types.h>
  26#include <linux/mm.h>
  27#include <linux/stddef.h>
  28#include <linux/init.h>
  29#include <linux/bootmem.h>
  30#include <linux/highmem.h>
  31#include <linux/initrd.h>
  32#include <linux/pagemap.h>
  33#include <linux/memblock.h>
  34#include <linux/gfp.h>
  35#include <linux/slab.h>
  36#include <linux/hugetlb.h>
  37
  38#include <asm/pgalloc.h>
  39#include <asm/prom.h>
  40#include <asm/io.h>
  41#include <asm/pgtable.h>
  42#include <asm/mmu.h>
  43#include <asm/smp.h>
  44#include <asm/machdep.h>
  45#include <asm/btext.h>
  46#include <asm/tlb.h>
  47#include <asm/sections.h>
  48#include <asm/system.h>
  49#include <asm/hugetlb.h>
  50
  51#include "mmu_decl.h"
  52
  53#if defined(CONFIG_KERNEL_START_BOOL) || defined(CONFIG_LOWMEM_SIZE_BOOL)
  54/* The amount of lowmem must be within 0xF0000000 - KERNELBASE. */
  55#if (CONFIG_LOWMEM_SIZE > (0xF0000000 - PAGE_OFFSET))
  56#error "You must adjust CONFIG_LOWMEM_SIZE or CONFIG_START_KERNEL"
  57#endif
  58#endif
  59#define MAX_LOW_MEM     CONFIG_LOWMEM_SIZE
  60
  61phys_addr_t total_memory;
  62phys_addr_t total_lowmem;
  63
  64phys_addr_t memstart_addr = (phys_addr_t)~0ull;
  65EXPORT_SYMBOL(memstart_addr);
  66phys_addr_t kernstart_addr;
  67EXPORT_SYMBOL(kernstart_addr);
  68
  69#ifdef CONFIG_RELOCATABLE_PPC32
  70/* Used in __va()/__pa() */
  71long long virt_phys_offset;
  72EXPORT_SYMBOL(virt_phys_offset);
  73#endif
  74
  75phys_addr_t lowmem_end_addr;
  76
  77int boot_mapsize;
  78#ifdef CONFIG_PPC_PMAC
  79unsigned long agp_special_page;
  80EXPORT_SYMBOL(agp_special_page);
  81#endif
  82
  83void MMU_init(void);
  84
  85/* XXX should be in current.h  -- paulus */
  86extern struct task_struct *current_set[NR_CPUS];
  87
  88/*
  89 * this tells the system to map all of ram with the segregs
  90 * (i.e. page tables) instead of the bats.
  91 * -- Cort
  92 */
  93int __map_without_bats;
  94int __map_without_ltlbs;
  95
  96/*
  97 * This tells the system to allow ioremapping memory marked as reserved.
  98 */
  99int __allow_ioremap_reserved;
 100
 101/* max amount of low RAM to map in */
 102unsigned long __max_low_memory = MAX_LOW_MEM;
 103
 104/*
 105 * Check for command-line options that affect what MMU_init will do.
 106 */
 107void MMU_setup(void)
 108{
 109        /* Check for nobats option (used in mapin_ram). */
 110        if (strstr(cmd_line, "nobats")) {
 111                __map_without_bats = 1;
 112        }
 113
 114        if (strstr(cmd_line, "noltlbs")) {
 115                __map_without_ltlbs = 1;
 116        }
 117#ifdef CONFIG_DEBUG_PAGEALLOC
 118        __map_without_bats = 1;
 119        __map_without_ltlbs = 1;
 120#endif
 121}
 122
 123/*
 124 * MMU_init sets up the basic memory mappings for the kernel,
 125 * including both RAM and possibly some I/O regions,
 126 * and sets up the page tables and the MMU hardware ready to go.
 127 */
 128void __init MMU_init(void)
 129{
 130        if (ppc_md.progress)
 131                ppc_md.progress("MMU:enter", 0x111);
 132
 133        /* parse args from command line */
 134        MMU_setup();
 135
 136        /*
 137         * Reserve gigantic pages for hugetlb.  This MUST occur before
 138         * lowmem_end_addr is initialized below.
 139         */
 140        reserve_hugetlb_gpages();
 141
 142        if (memblock.memory.cnt > 1) {
 143#ifndef CONFIG_WII
 144                memblock_enforce_memory_limit(memblock.memory.regions[0].size);
 145                printk(KERN_WARNING "Only using first contiguous memory region");
 146#else
 147                wii_memory_fixups();
 148#endif
 149        }
 150
 151        total_lowmem = total_memory = memblock_end_of_DRAM() - memstart_addr;
 152        lowmem_end_addr = memstart_addr + total_lowmem;
 153
 154#ifdef CONFIG_FSL_BOOKE
 155        /* Freescale Book-E parts expect lowmem to be mapped by fixed TLB
 156         * entries, so we need to adjust lowmem to match the amount we can map
 157         * in the fixed entries */
 158        adjust_total_lowmem();
 159#endif /* CONFIG_FSL_BOOKE */
 160
 161        if (total_lowmem > __max_low_memory) {
 162                total_lowmem = __max_low_memory;
 163                lowmem_end_addr = memstart_addr + total_lowmem;
 164#ifndef CONFIG_HIGHMEM
 165                total_memory = total_lowmem;
 166                memblock_enforce_memory_limit(total_lowmem);
 167#endif /* CONFIG_HIGHMEM */
 168        }
 169
 170        /* Initialize the MMU hardware */
 171        if (ppc_md.progress)
 172                ppc_md.progress("MMU:hw init", 0x300);
 173        MMU_init_hw();
 174
 175        /* Map in all of RAM starting at KERNELBASE */
 176        if (ppc_md.progress)
 177                ppc_md.progress("MMU:mapin", 0x301);
 178        mapin_ram();
 179
 180        /* Initialize early top-down ioremap allocator */
 181        ioremap_bot = IOREMAP_TOP;
 182
 183        /* Map in I/O resources */
 184        if (ppc_md.progress)
 185                ppc_md.progress("MMU:setio", 0x302);
 186
 187        if (ppc_md.progress)
 188                ppc_md.progress("MMU:exit", 0x211);
 189
 190        /* From now on, btext is no longer BAT mapped if it was at all */
 191#ifdef CONFIG_BOOTX_TEXT
 192        btext_unmap();
 193#endif
 194
 195        /* Shortly after that, the entire linear mapping will be available */
 196        memblock_set_current_limit(lowmem_end_addr);
 197}
 198
 199/* This is only called until mem_init is done. */
 200void __init *early_get_page(void)
 201{
 202        if (init_bootmem_done)
 203                return alloc_bootmem_pages(PAGE_SIZE);
 204        else
 205                return __va(memblock_alloc(PAGE_SIZE, PAGE_SIZE));
 206}
 207
 208#ifdef CONFIG_8xx /* No 8xx specific .c file to put that in ... */
 209void setup_initial_memory_limit(phys_addr_t first_memblock_base,
 210                                phys_addr_t first_memblock_size)
 211{
 212        /* We don't currently support the first MEMBLOCK not mapping 0
 213         * physical on those processors
 214         */
 215        BUG_ON(first_memblock_base != 0);
 216
 217        /* 8xx can only access 8MB at the moment */
 218        memblock_set_current_limit(min_t(u64, first_memblock_size, 0x00800000));
 219}
 220#endif /* CONFIG_8xx */
 221