init_32.c

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/*
 *  PowerPC version
 *    Copyright (C) 1995-1996 Gary Thomas ([email protected])
 *
 *  Modifications by Paul Mackerras (PowerMac) ([email protected])
 *  and Cort Dougan (PReP) ([email protected])
 *    Copyright (C) 1996 Paul Mackerras
 *  PPC44x/36-bit changes by Matt Porter ([email protected])
 *
 *  Derived from "arch/i386/mm/init.c"
 *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 *
 *  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.
 *
 */

#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/highmem.h>
#include <linux/initrd.h>
#include <linux/pagemap.h>
#include <linux/memblock.h>
#include <linux/gfp.h>
#include <linux/slab.h>
#include <linux/hugetlb.h>

#include <asm/pgalloc.h>
#include <asm/prom.h>
#include <asm/io.h>
#include <asm/pgtable.h>
#include <asm/mmu.h>
#include <asm/smp.h>
#include <asm/machdep.h>
#include <asm/btext.h>
#include <asm/tlb.h>
#include <asm/sections.h>
#include <asm/hugetlb.h>

#include "mmu_decl.h"

#if defined(CONFIG_KERNEL_START_BOOL) || defined(CONFIG_LOWMEM_SIZE_BOOL)
/* The amount of lowmem must be within 0xF0000000 - KERNELBASE. */
#if (CONFIG_LOWMEM_SIZE > (0xF0000000 - PAGE_OFFSET))
#error "You must adjust CONFIG_LOWMEM_SIZE or CONFIG_START_KERNEL"
#endif
#endif
#define MAX_LOW_MEM CONFIG_LOWMEM_SIZE

phys_addr_t total_memory;
phys_addr_t total_lowmem;

phys_addr_t memstart_addr = (phys_addr_t)~0ull;
EXPORT_SYMBOL(memstart_addr);
phys_addr_t kernstart_addr;
EXPORT_SYMBOL(kernstart_addr);

#ifdef CONFIG_RELOCATABLE_PPC32
/* Used in __va()/__pa() */
long long virt_phys_offset;
EXPORT_SYMBOL(virt_phys_offset);
#endif

phys_addr_t lowmem_end_addr;

int boot_mapsize;
#ifdef CONFIG_PPC_PMAC
unsigned long agp_special_page;
EXPORT_SYMBOL(agp_special_page);
#endif

void MMU_init(void);

/* XXX should be in current.h  -- paulus */
extern struct task_struct *current_set[NR_CPUS];

/*
 * this tells the system to map all of ram with the segregs
 * (i.e. page tables) instead of the bats.
 * -- Cort
 */
int __map_without_bats;
int __map_without_ltlbs;

/*
 * This tells the system to allow ioremapping memory marked as reserved.
 */
int __allow_ioremap_reserved;

/* max amount of low RAM to map in */
unsigned long __max_low_memory = MAX_LOW_MEM;

/*
 * Check for command-line options that affect what MMU_init will do.
 */
void MMU_setup(void)
{
    /* Check for nobats option (used in mapin_ram). */
    if (strstr(cmd_line, "nobats")) {
        __map_without_bats = 1;
    }

    if (strstr(cmd_line, "noltlbs")) {
        __map_without_ltlbs = 1;
    }
#ifdef CONFIG_DEBUG_PAGEALLOC
    __map_without_bats = 1;
    __map_without_ltlbs = 1;
#endif
}

/*
 * MMU_init sets up the basic memory mappings for the kernel,
 * including both RAM and possibly some I/O regions,
 * and sets up the page tables and the MMU hardware ready to go.
 */
void __init MMU_init(void)
{
    if (ppc_md.progress)
        ppc_md.progress("MMU:enter", 0x111);

    /* parse args from command line */
    MMU_setup();

    /*
     * Reserve gigantic pages for hugetlb.  This MUST occur before
     * lowmem_end_addr is initialized below.
     */
    reserve_hugetlb_gpages();

    if (memblock.memory.cnt > 1) {
#ifndef CONFIG_WII
        memblock_enforce_memory_limit(memblock.memory.regions[0].size);
        printk(KERN_WARNING "Only using first contiguous memory region");
#else
        wii_memory_fixups();
#endif
    }

    total_lowmem = total_memory = memblock_end_of_DRAM() - memstart_addr;
    lowmem_end_addr = memstart_addr + total_lowmem;

#ifdef CONFIG_FSL_BOOKE
    /* Freescale Book-E parts expect lowmem to be mapped by fixed TLB
     * entries, so we need to adjust lowmem to match the amount we can map
     * in the fixed entries */
    adjust_total_lowmem();
#endif /* CONFIG_FSL_BOOKE */

    if (total_lowmem > __max_low_memory) {
        total_lowmem = __max_low_memory;
        lowmem_end_addr = memstart_addr + total_lowmem;
#ifndef CONFIG_HIGHMEM
        total_memory = total_lowmem;
        memblock_enforce_memory_limit(total_lowmem);
#endif /* CONFIG_HIGHMEM */
    }

    /* Initialize the MMU hardware */
    if (ppc_md.progress)
        ppc_md.progress("MMU:hw init", 0x300);
    MMU_init_hw();

    /* Map in all of RAM starting at KERNELBASE */
    if (ppc_md.progress)
        ppc_md.progress("MMU:mapin", 0x301);
    mapin_ram();

    /* Initialize early top-down ioremap allocator */
    ioremap_bot = IOREMAP_TOP;

    /* Map in I/O resources */
    if (ppc_md.progress)
        ppc_md.progress("MMU:setio", 0x302);

    if (ppc_md.progress)
        ppc_md.progress("MMU:exit", 0x211);

    /* From now on, btext is no longer BAT mapped if it was at all */
#ifdef CONFIG_BOOTX_TEXT
    btext_unmap();
#endif

    /* Shortly after that, the entire linear mapping will be available */
    memblock_set_current_limit(lowmem_end_addr);
}

/* This is only called until mem_init is done. */
void __init *early_get_page(void)
{
    if (init_bootmem_done)
        return alloc_bootmem_pages(PAGE_SIZE);
    else
        return __va(memblock_alloc(PAGE_SIZE, PAGE_SIZE));
}

#ifdef CONFIG_8xx /* No 8xx specific .c file to put that in ... */
void setup_initial_memory_limit(phys_addr_t first_memblock_base,
                phys_addr_t first_memblock_size)
{
    /* We don't currently support the first MEMBLOCK not mapping 0
     * physical on those processors
     */
    BUG_ON(first_memblock_base != 0);

    /* 8xx can only access 8MB at the moment */
    memblock_set_current_limit(min_t(u64, first_memblock_size, 0x00800000));
}
#endif /* CONFIG_8xx */