ppc_mmu_32.c

Go to the documentation of this file.

/*
 * This file contains the routines for handling the MMU on those
 * PowerPC implementations where the MMU substantially follows the
 * architecture specification.  This includes the 6xx, 7xx, 7xxx,
 * 8260, and POWER3 implementations but excludes the 8xx and 4xx.
 *  -- paulus
 *
 *  Derived from arch/ppc/mm/init.c:
 *    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
 *
 *  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/kernel.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/highmem.h>
#include <linux/memblock.h>

#include <asm/prom.h>
#include <asm/mmu.h>
#include <asm/machdep.h>

#include "mmu_decl.h"

struct hash_pte *Hash, *Hash_end;
unsigned long Hash_size, Hash_mask;
unsigned long _SDR1;

struct ppc_bat BATS[8][2];  /* 8 pairs of IBAT, DBAT */

struct batrange {       /* stores address ranges mapped by BATs */
    unsigned long start;
    unsigned long limit;
    phys_addr_t phys;
} bat_addrs[8];

/*
 * Return PA for this VA if it is mapped by a BAT, or 0
 */
phys_addr_t v_mapped_by_bats(unsigned long va)
{
    int b;
    for (b = 0; b < 4; ++b)
        if (va >= bat_addrs[b].start && va < bat_addrs[b].limit)
            return bat_addrs[b].phys + (va - bat_addrs[b].start);
    return 0;
}

/*
 * Return VA for a given PA or 0 if not mapped
 */
unsigned long p_mapped_by_bats(phys_addr_t pa)
{
    int b;
    for (b = 0; b < 4; ++b)
        if (pa >= bat_addrs[b].phys
                && pa < (bat_addrs[b].limit-bat_addrs[b].start)
                      +bat_addrs[b].phys)
            return bat_addrs[b].start+(pa-bat_addrs[b].phys);
    return 0;
}

unsigned long __init mmu_mapin_ram(unsigned long top)
{
    unsigned long tot, bl, done;
    unsigned long max_size = (256<<20);

    if (__map_without_bats) {
        printk(KERN_DEBUG "RAM mapped without BATs\n");
        return 0;
    }

    /* Set up BAT2 and if necessary BAT3 to cover RAM. */

    /* Make sure we don't map a block larger than the
       smallest alignment of the physical address. */
    tot = top;
    for (bl = 128<<10; bl < max_size; bl <<= 1) {
        if (bl * 2 > tot)
            break;
    }

    setbat(2, PAGE_OFFSET, 0, bl, PAGE_KERNEL_X);
    done = (unsigned long)bat_addrs[2].limit - PAGE_OFFSET + 1;
    if ((done < tot) && !bat_addrs[3].limit) {
        /* use BAT3 to cover a bit more */
        tot -= done;
        for (bl = 128<<10; bl < max_size; bl <<= 1)
            if (bl * 2 > tot)
                break;
        setbat(3, PAGE_OFFSET+done, done, bl, PAGE_KERNEL_X);
        done = (unsigned long)bat_addrs[3].limit - PAGE_OFFSET + 1;
    }

    return done;
}

/*
 * Set up one of the I/D BAT (block address translation) register pairs.
 * The parameters are not checked; in particular size must be a power
 * of 2 between 128k and 256M.
 */
void __init setbat(int index, unsigned long virt, phys_addr_t phys,
           unsigned int size, int flags)
{
    unsigned int bl;
    int wimgxpp;
    struct ppc_bat *bat = BATS[index];

    if ((flags & _PAGE_NO_CACHE) ||
        (cpu_has_feature(CPU_FTR_NEED_COHERENT) == 0))
        flags &= ~_PAGE_COHERENT;

    bl = (size >> 17) - 1;
    if (PVR_VER(mfspr(SPRN_PVR)) != 1) {
        /* 603, 604, etc. */
        /* Do DBAT first */
        wimgxpp = flags & (_PAGE_WRITETHRU | _PAGE_NO_CACHE
                   | _PAGE_COHERENT | _PAGE_GUARDED);
        wimgxpp |= (flags & _PAGE_RW)? BPP_RW: BPP_RX;
        bat[1].batu = virt | (bl << 2) | 2; /* Vs=1, Vp=0 */
        bat[1].batl = BAT_PHYS_ADDR(phys) | wimgxpp;
        if (flags & _PAGE_USER)
            bat[1].batu |= 1;   /* Vp = 1 */
        if (flags & _PAGE_GUARDED) {
            /* G bit must be zero in IBATs */
            bat[0].batu = bat[0].batl = 0;
        } else {
            /* make IBAT same as DBAT */
            bat[0] = bat[1];
        }
    } else {
        /* 601 cpu */
        if (bl > BL_8M)
            bl = BL_8M;
        wimgxpp = flags & (_PAGE_WRITETHRU | _PAGE_NO_CACHE
                   | _PAGE_COHERENT);
        wimgxpp |= (flags & _PAGE_RW)?
            ((flags & _PAGE_USER)? PP_RWRW: PP_RWXX): PP_RXRX;
        bat->batu = virt | wimgxpp | 4; /* Ks=0, Ku=1 */
        bat->batl = phys | bl | 0x40;   /* V=1 */
    }

    bat_addrs[index].start = virt;
    bat_addrs[index].limit = virt + ((bl + 1) << 17) - 1;
    bat_addrs[index].phys = phys;
}

/*
 * Preload a translation in the hash table
 */
void hash_preload(struct mm_struct *mm, unsigned long ea,
          unsigned long access, unsigned long trap)
{
    pmd_t *pmd;

    if (Hash == 0)
        return;
    pmd = pmd_offset(pud_offset(pgd_offset(mm, ea), ea), ea);
    if (!pmd_none(*pmd))
        add_hash_page(mm->context.id, ea, pmd_val(*pmd));
}

/*
 * Initialize the hash table and patch the instructions in hashtable.S.
 */
void __init MMU_init_hw(void)
{
    unsigned int hmask, mb, mb2;
    unsigned int n_hpteg, lg_n_hpteg;

    extern unsigned int hash_page_patch_A[];
    extern unsigned int hash_page_patch_B[], hash_page_patch_C[];
    extern unsigned int hash_page[];
    extern unsigned int flush_hash_patch_A[], flush_hash_patch_B[];

    if (!mmu_has_feature(MMU_FTR_HPTE_TABLE)) {
        /*
         * Put a blr (procedure return) instruction at the
         * start of hash_page, since we can still get DSI
         * exceptions on a 603.
         */
        hash_page[0] = 0x4e800020;
        flush_icache_range((unsigned long) &hash_page[0],
                   (unsigned long) &hash_page[1]);
        return;
    }

    if ( ppc_md.progress ) ppc_md.progress("hash:enter", 0x105);

#define LG_HPTEG_SIZE   6       /* 64 bytes per HPTEG */
#define SDR1_LOW_BITS   ((n_hpteg - 1) >> 10)
#define MIN_N_HPTEG 1024        /* min 64kB hash table */

    /*
     * Allow 1 HPTE (1/8 HPTEG) for each page of memory.
     * This is less than the recommended amount, but then
     * Linux ain't AIX.
     */
    n_hpteg = total_memory / (PAGE_SIZE * 8);
    if (n_hpteg < MIN_N_HPTEG)
        n_hpteg = MIN_N_HPTEG;
    lg_n_hpteg = __ilog2(n_hpteg);
    if (n_hpteg & (n_hpteg - 1)) {
        ++lg_n_hpteg;       /* round up if not power of 2 */
        n_hpteg = 1 << lg_n_hpteg;
    }
    Hash_size = n_hpteg << LG_HPTEG_SIZE;

    /*
     * Find some memory for the hash table.
     */
    if ( ppc_md.progress ) ppc_md.progress("hash:find piece", 0x322);
    Hash = __va(memblock_alloc(Hash_size, Hash_size));
    cacheable_memzero(Hash, Hash_size);
    _SDR1 = __pa(Hash) | SDR1_LOW_BITS;

    Hash_end = (struct hash_pte *) ((unsigned long)Hash + Hash_size);

    printk("Total memory = %lldMB; using %ldkB for hash table (at %p)\n",
           (unsigned long long)(total_memory >> 20), Hash_size >> 10, Hash);


    /*
     * Patch up the instructions in hashtable.S:create_hpte
     */
    if ( ppc_md.progress ) ppc_md.progress("hash:patch", 0x345);
    Hash_mask = n_hpteg - 1;
    hmask = Hash_mask >> (16 - LG_HPTEG_SIZE);
    mb2 = mb = 32 - LG_HPTEG_SIZE - lg_n_hpteg;
    if (lg_n_hpteg > 16)
        mb2 = 16 - LG_HPTEG_SIZE;

    hash_page_patch_A[0] = (hash_page_patch_A[0] & ~0xffff)
        | ((unsigned int)(Hash) >> 16);
    hash_page_patch_A[1] = (hash_page_patch_A[1] & ~0x7c0) | (mb << 6);
    hash_page_patch_A[2] = (hash_page_patch_A[2] & ~0x7c0) | (mb2 << 6);
    hash_page_patch_B[0] = (hash_page_patch_B[0] & ~0xffff) | hmask;
    hash_page_patch_C[0] = (hash_page_patch_C[0] & ~0xffff) | hmask;

    /*
     * Ensure that the locations we've patched have been written
     * out from the data cache and invalidated in the instruction
     * cache, on those machines with split caches.
     */
    flush_icache_range((unsigned long) &hash_page_patch_A[0],
               (unsigned long) &hash_page_patch_C[1]);

    /*
     * Patch up the instructions in hashtable.S:flush_hash_page
     */
    flush_hash_patch_A[0] = (flush_hash_patch_A[0] & ~0xffff)
        | ((unsigned int)(Hash) >> 16);
    flush_hash_patch_A[1] = (flush_hash_patch_A[1] & ~0x7c0) | (mb << 6);
    flush_hash_patch_A[2] = (flush_hash_patch_A[2] & ~0x7c0) | (mb2 << 6);
    flush_hash_patch_B[0] = (flush_hash_patch_B[0] & ~0xffff) | hmask;
    flush_icache_range((unsigned long) &flush_hash_patch_A[0],
               (unsigned long) &flush_hash_patch_B[1]);

    if ( ppc_md.progress ) ppc_md.progress("hash:done", 0x205);
}

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);

    /* 601 can only access 16MB at the moment */
    if (PVR_VER(mfspr(SPRN_PVR)) == 1)
        memblock_set_current_limit(min_t(u64, first_memblock_size, 0x01000000));
    else /* Anything else has 256M mapped */
        memblock_set_current_limit(min_t(u64, first_memblock_size, 0x10000000));
}