motorola.c

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/*
 * linux/arch/m68k/mm/motorola.c
 *
 * Routines specific to the Motorola MMU, originally from:
 * linux/arch/m68k/init.c
 * which are Copyright (C) 1995 Hamish Macdonald
 *
 * Moved 8/20/1999 Sam Creasey
 */

#include <linux/module.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/gfp.h>

#include <asm/setup.h>
#include <asm/uaccess.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/machdep.h>
#include <asm/io.h>
#include <asm/dma.h>
#ifdef CONFIG_ATARI
#include <asm/atari_stram.h>
#endif
#include <asm/sections.h>

#undef DEBUG

#ifndef mm_cachebits
/*
 * Bits to add to page descriptors for "normal" caching mode.
 * For 68020/030 this is 0.
 * For 68040, this is _PAGE_CACHE040 (cachable, copyback)
 */
unsigned long mm_cachebits;
EXPORT_SYMBOL(mm_cachebits);
#endif

/* size of memory already mapped in head.S */
#define INIT_MAPPED_SIZE    (4UL<<20)

extern unsigned long availmem;

static pte_t * __init kernel_page_table(void)
{
    pte_t *ptablep;

    ptablep = (pte_t *)alloc_bootmem_low_pages(PAGE_SIZE);

    clear_page(ptablep);
    __flush_page_to_ram(ptablep);
    flush_tlb_kernel_page(ptablep);
    nocache_page(ptablep);

    return ptablep;
}

static pmd_t *last_pgtable __initdata = NULL;
pmd_t *zero_pgtable __initdata = NULL;

static pmd_t * __init kernel_ptr_table(void)
{
    if (!last_pgtable) {
        unsigned long pmd, last;
        int i;

        /* Find the last ptr table that was used in head.S and
         * reuse the remaining space in that page for further
         * ptr tables.
         */
        last = (unsigned long)kernel_pg_dir;
        for (i = 0; i < PTRS_PER_PGD; i++) {
            if (!pgd_present(kernel_pg_dir[i]))
                continue;
            pmd = __pgd_page(kernel_pg_dir[i]);
            if (pmd > last)
                last = pmd;
        }

        last_pgtable = (pmd_t *)last;
#ifdef DEBUG
        printk("kernel_ptr_init: %p\n", last_pgtable);
#endif
    }

    last_pgtable += PTRS_PER_PMD;
    if (((unsigned long)last_pgtable & ~PAGE_MASK) == 0) {
        last_pgtable = (pmd_t *)alloc_bootmem_low_pages(PAGE_SIZE);

        clear_page(last_pgtable);
        __flush_page_to_ram(last_pgtable);
        flush_tlb_kernel_page(last_pgtable);
        nocache_page(last_pgtable);
    }

    return last_pgtable;
}

static void __init map_node(int node)
{
#define PTRTREESIZE (256*1024)
#define ROOTTREESIZE (32*1024*1024)
    unsigned long physaddr, virtaddr, size;
    pgd_t *pgd_dir;
    pmd_t *pmd_dir;
    pte_t *pte_dir;

    size = m68k_memory[node].size;
    physaddr = m68k_memory[node].addr;
    virtaddr = (unsigned long)phys_to_virt(physaddr);
    physaddr |= m68k_supervisor_cachemode |
            _PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_DIRTY;
    if (CPU_IS_040_OR_060)
        physaddr |= _PAGE_GLOBAL040;

    while (size > 0) {
#ifdef DEBUG
        if (!(virtaddr & (PTRTREESIZE-1)))
            printk ("\npa=%#lx va=%#lx ", physaddr & PAGE_MASK,
                virtaddr);
#endif
        pgd_dir = pgd_offset_k(virtaddr);
        if (virtaddr && CPU_IS_020_OR_030) {
            if (!(virtaddr & (ROOTTREESIZE-1)) &&
                size >= ROOTTREESIZE) {
#ifdef DEBUG
                printk ("[very early term]");
#endif
                pgd_val(*pgd_dir) = physaddr;
                size -= ROOTTREESIZE;
                virtaddr += ROOTTREESIZE;
                physaddr += ROOTTREESIZE;
                continue;
            }
        }
        if (!pgd_present(*pgd_dir)) {
            pmd_dir = kernel_ptr_table();
#ifdef DEBUG
            printk ("[new pointer %p]", pmd_dir);
#endif
            pgd_set(pgd_dir, pmd_dir);
        } else
            pmd_dir = pmd_offset(pgd_dir, virtaddr);

        if (CPU_IS_020_OR_030) {
            if (virtaddr) {
#ifdef DEBUG
                printk ("[early term]");
#endif
                pmd_dir->pmd[(virtaddr/PTRTREESIZE) & 15] = physaddr;
                physaddr += PTRTREESIZE;
            } else {
                int i;
#ifdef DEBUG
                printk ("[zero map]");
#endif
                zero_pgtable = kernel_ptr_table();
                pte_dir = (pte_t *)zero_pgtable;
                pmd_dir->pmd[0] = virt_to_phys(pte_dir) |
                    _PAGE_TABLE | _PAGE_ACCESSED;
                pte_val(*pte_dir++) = 0;
                physaddr += PAGE_SIZE;
                for (i = 1; i < 64; physaddr += PAGE_SIZE, i++)
                    pte_val(*pte_dir++) = physaddr;
            }
            size -= PTRTREESIZE;
            virtaddr += PTRTREESIZE;
        } else {
            if (!pmd_present(*pmd_dir)) {
#ifdef DEBUG
                printk ("[new table]");
#endif
                pte_dir = kernel_page_table();
                pmd_set(pmd_dir, pte_dir);
            }
            pte_dir = pte_offset_kernel(pmd_dir, virtaddr);

            if (virtaddr) {
                if (!pte_present(*pte_dir))
                    pte_val(*pte_dir) = physaddr;
            } else
                pte_val(*pte_dir) = 0;
            size -= PAGE_SIZE;
            virtaddr += PAGE_SIZE;
            physaddr += PAGE_SIZE;
        }

    }
#ifdef DEBUG
    printk("\n");
#endif
}

/*
 * paging_init() continues the virtual memory environment setup which
 * was begun by the code in arch/head.S.
 */
void __init paging_init(void)
{
    unsigned long zones_size[MAX_NR_ZONES] = { 0, };
    unsigned long min_addr, max_addr;
    unsigned long addr, size, end;
    int i;

#ifdef DEBUG
    printk ("start of paging_init (%p, %lx)\n", kernel_pg_dir, availmem);
#endif

    /* Fix the cache mode in the page descriptors for the 680[46]0.  */
    if (CPU_IS_040_OR_060) {
        int i;
#ifndef mm_cachebits
        mm_cachebits = _PAGE_CACHE040;
#endif
        for (i = 0; i < 16; i++)
            pgprot_val(protection_map[i]) |= _PAGE_CACHE040;
    }

    min_addr = m68k_memory[0].addr;
    max_addr = min_addr + m68k_memory[0].size;
    for (i = 1; i < m68k_num_memory;) {
        if (m68k_memory[i].addr < min_addr) {
            printk("Ignoring memory chunk at 0x%lx:0x%lx before the first chunk\n",
                m68k_memory[i].addr, m68k_memory[i].size);
            printk("Fix your bootloader or use a memfile to make use of this area!\n");
            m68k_num_memory--;
            memmove(m68k_memory + i, m68k_memory + i + 1,
                (m68k_num_memory - i) * sizeof(struct mem_info));
            continue;
        }
        addr = m68k_memory[i].addr + m68k_memory[i].size;
        if (addr > max_addr)
            max_addr = addr;
        i++;
    }
    m68k_memoffset = min_addr - PAGE_OFFSET;
    m68k_virt_to_node_shift = fls(max_addr - min_addr - 1) - 6;

    module_fixup(NULL, __start_fixup, __stop_fixup);
    flush_icache();

    high_memory = phys_to_virt(max_addr);

    min_low_pfn = availmem >> PAGE_SHIFT;
    max_low_pfn = max_addr >> PAGE_SHIFT;

    for (i = 0; i < m68k_num_memory; i++) {
        addr = m68k_memory[i].addr;
        end = addr + m68k_memory[i].size;
        m68k_setup_node(i);
        availmem = PAGE_ALIGN(availmem);
        availmem += init_bootmem_node(NODE_DATA(i),
                          availmem >> PAGE_SHIFT,
                          addr >> PAGE_SHIFT,
                          end >> PAGE_SHIFT);
    }

    /*
     * Map the physical memory available into the kernel virtual
     * address space. First initialize the bootmem allocator with
     * the memory we already mapped, so map_node() has something
     * to allocate.
     */
    addr = m68k_memory[0].addr;
    size = m68k_memory[0].size;
    free_bootmem_node(NODE_DATA(0), availmem, min(INIT_MAPPED_SIZE, size) - (availmem - addr));
    map_node(0);
    if (size > INIT_MAPPED_SIZE)
        free_bootmem_node(NODE_DATA(0), addr + INIT_MAPPED_SIZE, size - INIT_MAPPED_SIZE);

    for (i = 1; i < m68k_num_memory; i++)
        map_node(i);

    flush_tlb_all();

    /*
     * initialize the bad page table and bad page to point
     * to a couple of allocated pages
     */
    empty_zero_page = alloc_bootmem_pages(PAGE_SIZE);

    /*
     * Set up SFC/DFC registers
     */
    set_fs(KERNEL_DS);

#ifdef DEBUG
    printk ("before free_area_init\n");
#endif
    for (i = 0; i < m68k_num_memory; i++) {
        zones_size[ZONE_DMA] = m68k_memory[i].size >> PAGE_SHIFT;
        free_area_init_node(i, zones_size,
                    m68k_memory[i].addr >> PAGE_SHIFT, NULL);
        if (node_present_pages(i))
            node_set_state(i, N_NORMAL_MEMORY);
    }
}

void free_initmem(void)
{
    unsigned long addr;

    addr = (unsigned long)__init_begin;
    for (; addr < (unsigned long)__init_end; addr += PAGE_SIZE) {
        virt_to_page(addr)->flags &= ~(1 << PG_reserved);
        init_page_count(virt_to_page(addr));
        free_page(addr);
        totalram_pages++;
    }
}