/*
 *  linux/mm/bootmem.c
 *
 *  Copyright (C) 1999 Ingo Molnar
 *  Discontiguous memory support, Kanoj Sarcar, SGI, Nov 1999
 *
 *  simple boot-time physical memory area allocator and
 *  free memory collector. It's used to deal with reserved
 *  system memory and memory holes as well.
 */

#include <linux/mm.h>
#include <linux/kernel_stat.h>
#include <linux/swap.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/mmzone.h>
#include <linux/module.h>
#include <asm/dma.h>
#include <asm/io.h>

/*
 * Access to this subsystem has to be serialized externally. (this is
 * true for the boot process anyway)
 */
unsigned long max_low_pfn;
unsigned long min_low_pfn;
unsigned long max_pfn;

EXPORT_SYMBOL(max_pfn);         /* This is exported so
                                 * dma_get_required_mask(), which uses
                                 * it, can be an inline function */

/* return the number of _pages_ that will be allocated for the boot bitmap */
unsigned long __init bootmem_bootmap_pages (unsigned long pages)
{
        unsigned long mapsize;

        mapsize = (pages+7)/8;
        mapsize = (mapsize + ~PAGE_MASK) & PAGE_MASK;
        mapsize >>= PAGE_SHIFT;

        return mapsize;
}

/*
 * Called once to set up the allocator itself.
 */
static unsigned long __init init_bootmem_core (pg_data_t *pgdat,
        unsigned long mapstart, unsigned long start, unsigned long end)
{
        bootmem_data_t *bdata = pgdat->bdata;
        unsigned long mapsize = ((end - start)+7)/8;

        pgdat->pgdat_next = pgdat_list;
        pgdat_list = pgdat;

        mapsize = (mapsize + (sizeof(long) - 1UL)) & ~(sizeof(long) - 1UL);
        bdata->node_bootmem_map = phys_to_virt(mapstart << PAGE_SHIFT);
        bdata->node_boot_start = (start << PAGE_SHIFT);
        bdata->node_low_pfn = end;

        /*
         * Initially all pages are reserved - setup_arch() has to
         * register free RAM areas explicitly.
         */
        memset(bdata->node_bootmem_map, 0xff, mapsize);

        return mapsize;
}

/*
 * Marks a particular physical memory range as unallocatable. Usable RAM
 * might be used for boot-time allocations - or it might get added
 * to the free page pool later on.
 */
static void __init reserve_bootmem_core(bootmem_data_t *bdata, unsigned long addr, unsigned long size)
{
        unsigned long i;
        /*
         * round up, partially reserved pages are considered
         * fully reserved.
         */
        unsigned long sidx = (addr - bdata->node_boot_start)/PAGE_SIZE;
        unsigned long eidx = (addr + size - bdata->node_boot_start + 
                                                        PAGE_SIZE-1)/PAGE_SIZE;
        unsigned long end = (addr + size + PAGE_SIZE-1)/PAGE_SIZE;

        BUG_ON(!size);
        BUG_ON(sidx >= eidx);
        BUG_ON((addr >> PAGE_SHIFT) >= bdata->node_low_pfn);
        BUG_ON(end > bdata->node_low_pfn);

        for (i = sidx; i < eidx; i++)
                if (test_and_set_bit(i, bdata->node_bootmem_map)) {
#ifdef CONFIG_DEBUG_BOOTMEM
                        printk("hm, page %08lx reserved twice.\n", i*PAGE_SIZE);
#endif
                }
}

static void __init free_bootmem_core(bootmem_data_t *bdata, unsigned long addr, unsigned long size)
{
        unsigned long i;
        unsigned long start;
        /*
         * round down end of usable mem, partially free pages are
         * considered reserved.
         */
        unsigned long sidx;
        unsigned long eidx = (addr + size - bdata->node_boot_start)/PAGE_SIZE;
        unsigned long end = (addr + size)/PAGE_SIZE;

        BUG_ON(!size);
        BUG_ON(end > bdata->node_low_pfn);

        if (addr < bdata->last_success)
                bdata->last_success = addr;

        /*
         * Round up the beginning of the address.
         */
        start = (addr + PAGE_SIZE-1) / PAGE_SIZE;
        sidx = start - (bdata->node_boot_start/PAGE_SIZE);

        for (i = sidx; i < eidx; i++) {
                if (unlikely(!test_and_clear_bit(i, bdata->node_bootmem_map)))
                        BUG();
        }
}

/*
 * We 'merge' subsequent allocations to save space. We might 'lose'
 * some fraction of a page if allocations cannot be satisfied due to
 * size constraints on boxes where there is physical RAM space
 * fragmentation - in these cases (mostly large memory boxes) this
 * is not a problem.
 *
 * On low memory boxes we get it right in 100% of the cases.
 *
 * alignment has to be a power of 2 value.
 *
 * NOTE:  This function is _not_ reentrant.
 */
static void * __init
__alloc_bootmem_core(struct bootmem_data *bdata, unsigned long size,
                unsigned long align, unsigned long goal)
{
        unsigned long offset, remaining_size, areasize, preferred;
        unsigned long i, start = 0, incr, eidx;
        void *ret;

        if(!size) {
                printk("__alloc_bootmem_core(): zero-sized request\n");
                BUG();
        }
        BUG_ON(align & (align-1));

        eidx = bdata->node_low_pfn - (bdata->node_boot_start >> PAGE_SHIFT);
        offset = 0;
        if (align &&
            (bdata->node_boot_start & (align - 1UL)) != 0)
                offset = (align - (bdata->node_boot_start & (align - 1UL)));
        offset >>= PAGE_SHIFT;

        /*
         * We try to allocate bootmem pages above 'goal'
         * first, then we try to allocate lower pages.
         */
        if (goal && (goal >= bdata->node_boot_start) && 
            ((goal >> PAGE_SHIFT) < bdata->node_low_pfn)) {
                preferred = goal - bdata->node_boot_start;

                if (bdata->last_success >= preferred)
                        preferred = bdata->last_success;
        } else
                preferred = 0;

        preferred = ((preferred + align - 1) & ~(align - 1)) >> PAGE_SHIFT;
        preferred += offset;
        areasize = (size+PAGE_SIZE-1)/PAGE_SIZE;
        incr = align >> PAGE_SHIFT ? : 1;

restart_scan:
        for (i = preferred; i < eidx; i += incr) {
                unsigned long j;
                i = find_next_zero_bit(bdata->node_bootmem_map, eidx, i);
                i = ALIGN(i, incr);
                if (test_bit(i, bdata->node_bootmem_map))
                        continue;
                for (j = i + 1; j < i + areasize; ++j) {
                        if (j >= eidx)
                                goto fail_block;
                        if (test_bit (j, bdata->node_bootmem_map))
                                goto fail_block;
                }
                start = i;
                goto found;
        fail_block:
                i = ALIGN(j, incr);
        }

        if (preferred > offset) {
                preferred = offset;
                goto restart_scan;
        }
        return NULL;

found:
        bdata->last_success = start << PAGE_SHIFT;
        BUG_ON(start >= eidx);

        /*
         * Is the next page of the previous allocation-end the start
         * of this allocation's buffer? If yes then we can 'merge'
         * the previous partial page with this allocation.
         */
        if (align < PAGE_SIZE &&
            bdata->last_offset && bdata->last_pos+1 == start) {
                offset = (bdata->last_offset+align-1) & ~(align-1);
                BUG_ON(offset > PAGE_SIZE);
                remaining_size = PAGE_SIZE-offset;
                if (size < remaining_size) {
                        areasize = 0;
                        /* last_pos unchanged */
                        bdata->last_offset = offset+size;
                        ret = phys_to_virt(bdata->last_pos*PAGE_SIZE + offset +
                                                bdata->node_boot_start);
                } else {
                        remaining_size = size - remaining_size;
                        areasize = (remaining_size+PAGE_SIZE-1)/PAGE_SIZE;
                        ret = phys_to_virt(bdata->last_pos*PAGE_SIZE + offset +
                                                bdata->node_boot_start);
                        bdata->last_pos = start+areasize-1;
                        bdata->last_offset = remaining_size;
                }
                bdata->last_offset &= ~PAGE_MASK;
        } else {
                bdata->last_pos = start + areasize - 1;
                bdata->last_offset = size & ~PAGE_MASK;
                ret = phys_to_virt(start * PAGE_SIZE + bdata->node_boot_start);
        }

        /*
         * Reserve the area now:
         */
        for (i = start; i < start+areasize; i++)
                if (unlikely(test_and_set_bit(i, bdata->node_bootmem_map)))
                        BUG();
        memset(ret, 0, size);
        return ret;
}

static unsigned long __init free_all_bootmem_core(pg_data_t *pgdat)
{
        struct page *page;
        bootmem_data_t *bdata = pgdat->bdata;
        unsigned long i, count, total = 0;
        unsigned long idx;
        unsigned long *map; 

        BUG_ON(!bdata->node_bootmem_map);

        count = 0;
        /* first extant page of the node */
        page = virt_to_page(phys_to_virt(bdata->node_boot_start));
        idx = bdata->node_low_pfn - (bdata->node_boot_start >> PAGE_SHIFT);
        map = bdata->node_bootmem_map;
        for (i = 0; i < idx; ) {
                unsigned long v = ~map[i / BITS_PER_LONG];
                if (v) {
                        unsigned long m;
                        for (m = 1; m && i < idx; m<<=1, page++, i++) {
                                if (v & m) {
                                        count++;
                                        ClearPageReserved(page);
                                        set_page_count(page, 1);
                                        __free_page(page);
                                }
                        }
                } else {
                        i+=BITS_PER_LONG;
                        page += BITS_PER_LONG;
                }
        }
        total += count;

        /*
         * Now free the allocator bitmap itself, it's not
         * needed anymore:
         */
        page = virt_to_page(bdata->node_bootmem_map);
        count = 0;
        for (i = 0; i < ((bdata->node_low_pfn-(bdata->node_boot_start >> PAGE_SHIFT))/8 + PAGE_SIZE-1)/PAGE_SIZE; i++,page++) {
                count++;
                ClearPageReserved(page);
                set_page_count(page, 1);
                __free_page(page);
        }
        total += count;
        bdata->node_bootmem_map = NULL;

        return total;
}

unsigned long __init init_bootmem_node (pg_data_t *pgdat, unsigned long freepfn, unsigned long startpfn, unsigned long endpfn)
{
        return(init_bootmem_core(pgdat, freepfn, startpfn, endpfn));
}

void __init reserve_bootmem_node (pg_data_t *pgdat, unsigned long physaddr, unsigned long size)
{
        reserve_bootmem_core(pgdat->bdata, physaddr, size);
}

void __init free_bootmem_node (pg_data_t *pgdat, unsigned long physaddr, unsigned long size)
{
        free_bootmem_core(pgdat->bdata, physaddr, size);
}

unsigned long __init free_all_bootmem_node (pg_data_t *pgdat)
{
        return(free_all_bootmem_core(pgdat));
}

#ifndef CONFIG_DISCONTIGMEM
unsigned long __init init_bootmem (unsigned long start, unsigned long pages)
{
        max_low_pfn = pages;
        min_low_pfn = start;
        return(init_bootmem_core(&contig_page_data, start, 0, pages));
}

#ifndef CONFIG_HAVE_ARCH_BOOTMEM_NODE
void __init reserve_bootmem (unsigned long addr, unsigned long size)
{
        reserve_bootmem_core(contig_page_data.bdata, addr, size);
}
#endif /* !CONFIG_HAVE_ARCH_BOOTMEM_NODE */

void __init free_bootmem (unsigned long addr, unsigned long size)
{
        free_bootmem_core(contig_page_data.bdata, addr, size);
}

unsigned long __init free_all_bootmem (void)
{
        return(free_all_bootmem_core(&contig_page_data));
}
#endif /* !CONFIG_DISCONTIGMEM */

void * __init __alloc_bootmem (unsigned long size, unsigned long align, unsigned long goal)
{
        pg_data_t *pgdat = pgdat_list;
        void *ptr;

        for_each_pgdat(pgdat)
                if ((ptr = __alloc_bootmem_core(pgdat->bdata, size,
                                                align, goal)))
                        return(ptr);

        /*
         * Whoops, we cannot satisfy the allocation request.
         */
        printk(KERN_ALERT "bootmem alloc of %lu bytes failed!\n", size);
        panic("Out of memory");
        return NULL;
}

void * __init __alloc_bootmem_node (pg_data_t *pgdat, unsigned long size, unsigned long align, unsigned long goal)
{
        void *ptr;

        ptr = __alloc_bootmem_core(pgdat->bdata, size, align, goal);
        if (ptr)
                return (ptr);

        return __alloc_bootmem(size, align, goal);
}