arch/powerpc/mm/init_32.c

   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/highmem.h>
  30 #include <linux/initrd.h>
  31 #include <linux/pagemap.h>
  32 #include <linux/memblock.h>
  33 #include <linux/gfp.h>
  34 #include <linux/slab.h>
  35 #include <linux/hugetlb.h>
  36
  37 #include <asm/pgalloc.h>
  38 #include <asm/prom.h>
  39 #include <asm/io.h>
  40 #include <asm/pgtable.h>
  41 #include <asm/mmu.h>
  42 #include <asm/smp.h>
  43 #include <asm/machdep.h>
  44 #include <asm/btext.h>
  45 #include <asm/tlb.h>
  46 #include <asm/sections.h>
  47 #include <asm/hugetlb.h>
  48
  49 #include "mmu_decl.h"
  50
  51 #if defined(CONFIG_KERNEL_START_BOOL) || defined(CONFIG_LOWMEM_SIZE_BOOL)
  52 /* The amount of lowmem must be within 0xF0000000 - KERNELBASE. */
  53 #if (CONFIG_LOWMEM_SIZE > (0xF0000000 - PAGE_OFFSET))
  54 #error "You must adjust CONFIG_LOWMEM_SIZE or CONFIG_KERNEL_START"
  55 #endif
  56 #endif
  57 #define MAX_LOW_MEM     CONFIG_LOWMEM_SIZE
  58
  59 phys_addr_t total_memory;
  60 phys_addr_t total_lowmem;
  61
  62 phys_addr_t memstart_addr = (phys_addr_t)~0ull;
  63 EXPORT_SYMBOL(memstart_addr);
  64 phys_addr_t kernstart_addr;
  65 EXPORT_SYMBOL(kernstart_addr);
  66
  67 #ifdef CONFIG_RELOCATABLE
  68 /* Used in __va()/__pa() */
  69 long long virt_phys_offset;
  70 EXPORT_SYMBOL(virt_phys_offset);
  71 #endif
  72
  73 phys_addr_t lowmem_end_addr;
  74
  75 int boot_mapsize;
  76 #ifdef CONFIG_PPC_PMAC
  77 unsigned long agp_special_page;
  78 EXPORT_SYMBOL(agp_special_page);
  79 #endif
  80
  81 void MMU_init(void);
  82
  83 /*
  84  * this tells the system to map all of ram with the segregs
  85  * (i.e. page tables) instead of the bats.
  86  * -- Cort
  87  */
  88 int __map_without_bats;
  89 int __map_without_ltlbs;
  90
  91 /* max amount of low RAM to map in */
  92 unsigned long __max_low_memory = MAX_LOW_MEM;
  93
  94 /*
  95  * Check for command-line options that affect what MMU_init will do.
  96  */
  97 static void __init MMU_setup(void)
  98 {
  99         /* Check for nobats option (used in mapin_ram). */
 100         if (strstr(boot_command_line, "nobats")) {
 101                 __map_without_bats = 1;
 102         }
 103
 104         if (strstr(boot_command_line, "noltlbs")) {
 105                 __map_without_ltlbs = 1;
 106         }
 107         if (debug_pagealloc_enabled()) {
 108                 __map_without_bats = 1;
 109                 __map_without_ltlbs = 1;
 110         }
 111         if (strict_kernel_rwx_enabled())
 112                 __map_without_ltlbs = 1;
 113 }
 114
 115 /*
 116  * MMU_init sets up the basic memory mappings for the kernel,
 117  * including both RAM and possibly some I/O regions,
 118  * and sets up the page tables and the MMU hardware ready to go.
 119  */
 120 void __init MMU_init(void)
 121 {
 122         if (ppc_md.progress)
 123                 ppc_md.progress("MMU:enter", 0x111);
 124
 125         /* parse args from command line */
 126         MMU_setup();
 127
 128         /*
 129          * Reserve gigantic pages for hugetlb.  This MUST occur before
 130          * lowmem_end_addr is initialized below.
 131          */
 132         if (memblock.memory.cnt > 1) {
 133 #ifndef CONFIG_WII
 134                 memblock_enforce_memory_limit(memblock.memory.regions[0].size);
 135                 pr_warn("Only using first contiguous memory region\n");
 136 #else
 137                 wii_memory_fixups();
 138 #endif
 139         }
 140
 141         total_lowmem = total_memory = memblock_end_of_DRAM() - memstart_addr;
 142         lowmem_end_addr = memstart_addr + total_lowmem;
 143
 144 #ifdef CONFIG_FSL_BOOKE
 145         /* Freescale Book-E parts expect lowmem to be mapped by fixed TLB
 146          * entries, so we need to adjust lowmem to match the amount we can map
 147          * in the fixed entries */
 148         adjust_total_lowmem();
 149 #endif /* CONFIG_FSL_BOOKE */
 150
 151         if (total_lowmem > __max_low_memory) {
 152                 total_lowmem = __max_low_memory;
 153                 lowmem_end_addr = memstart_addr + total_lowmem;
 154 #ifndef CONFIG_HIGHMEM
 155                 total_memory = total_lowmem;
 156                 memblock_enforce_memory_limit(total_lowmem);
 157 #endif /* CONFIG_HIGHMEM */
 158         }
 159
 160         /* Initialize the MMU hardware */
 161         if (ppc_md.progress)
 162                 ppc_md.progress("MMU:hw init", 0x300);
 163         MMU_init_hw();
 164
 165         /* Map in all of RAM starting at KERNELBASE */
 166         if (ppc_md.progress)
 167                 ppc_md.progress("MMU:mapin", 0x301);
 168         mapin_ram();
 169
 170         /* Initialize early top-down ioremap allocator */
 171         ioremap_bot = IOREMAP_TOP;
 172
 173         if (ppc_md.progress)
 174                 ppc_md.progress("MMU:exit", 0x211);
 175
 176         /* From now on, btext is no longer BAT mapped if it was at all */
 177 #ifdef CONFIG_BOOTX_TEXT
 178         btext_unmap();
 179 #endif
 180
 181         /* Shortly after that, the entire linear mapping will be available */
 182         memblock_set_current_limit(lowmem_end_addr);
 183 }