/*
 *  linux/mm/kmalloc.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds & Roger Wolff.
 *
 *  Written by R.E. Wolff Sept/Oct '93.
 *
 */

/*
 * Modified by Alex Bligh (alex@cconcepts.co.uk) 4 Apr 1994 to use multiple
 * pages. So for 'page' throughout, read 'area'.
 */

#include <linux/mm.h>
#include <linux/delay.h>
#include <asm/system.h>
#include <asm/dma.h>

/* I want this low enough for a while to catch errors.
   I want this number to be increased in the near future:
        loadable device drivers should use this function to get memory */

#define MAX_KMALLOC_K ((PAGE_SIZE<<(NUM_AREA_ORDERS-1))>>10)


/* This defines how many times we should try to allocate a free page before
   giving up. Normally this shouldn't happen at all. */
#define MAX_GET_FREE_PAGE_TRIES 4


/* Private flags. */

#define MF_USED 0xffaa0055
#define MF_DMA  0xff00aa55
#define MF_FREE 0x0055ffaa


/*
 * Much care has gone into making these routines in this file reentrant.
 *
 * The fancy bookkeeping of nbytesmalloced and the like are only used to
 * report them to the user (oooohhhhh, aaaaahhhhh....) are not
 * protected by cli(). (If that goes wrong. So what?)
 *
 * These routines restore the interrupt status to allow calling with ints
 * off.
 */

/*
 * A block header. This is in front of every malloc-block, whether free or not.
 */
struct block_header {
	unsigned long bh_flags;
	union {
		unsigned long ubh_length;
		struct block_header *fbh_next;
	} vp;
};


#define bh_length vp.ubh_length
#define bh_next   vp.fbh_next
#define BH(p) ((struct block_header *)(p))


/*
 * The page descriptor is at the front of every page that malloc has in use.
 */
struct page_descriptor {
	struct page_descriptor *next;
	struct block_header *firstfree;
	int order;
	int nfree;
};


#define PAGE_DESC(p) ((struct page_descriptor *)(((unsigned long)(p)) & PAGE_MASK))


/*
 * A size descriptor describes a specific class of malloc sizes.
 * Each class of sizes has its own freelist.
 */
struct size_descriptor {
	struct page_descriptor *firstfree;
	struct page_descriptor *dmafree;	/* DMA-able memory */
	int size;
	int nblocks;

	int nmallocs;
	int nfrees;
	int nbytesmalloced;
	int npages;
	unsigned long gfporder;	/* number of pages in the area required */
};

/*
 * For now it is unsafe to allocate bucket sizes between n & n=16 where n is
 * 4096 * any power of two
 */
#if PAGE_SIZE == 4096
struct size_descriptor sizes[] =
{
	{NULL, NULL, 32, 127, 0, 0, 0, 0, 0},
	{NULL, NULL, 64, 63, 0, 0, 0, 0, 0},
	{NULL, NULL, 128, 31, 0, 0, 0, 0, 0},
	{NULL, NULL, 252, 16, 0, 0, 0, 0, 0},
	{NULL, NULL, 508, 8, 0, 0, 0, 0, 0},
	{NULL, NULL, 1020, 4, 0, 0, 0, 0, 0},
	{NULL, NULL, 2040, 2, 0, 0, 0, 0, 0},
	{NULL, NULL, 4096 - 16, 1, 0, 0, 0, 0, 0},
	{NULL, NULL, 8192 - 16, 1, 0, 0, 0, 0, 1},
	{NULL, NULL, 16384 - 16, 1, 0, 0, 0, 0, 2},
	{NULL, NULL, 32768 - 16, 1, 0, 0, 0, 0, 3},
	{NULL, NULL, 65536 - 16, 1, 0, 0, 0, 0, 4},
	{NULL, NULL, 131072 - 16, 1, 0, 0, 0, 0, 5},
	{NULL, NULL, 0, 0, 0, 0, 0, 0, 0}
};
#elif PAGE_SIZE == 8192
struct size_descriptor sizes[] =
{
	{NULL, NULL, 64, 127, 0, 0, 0, 0, 0},
	{NULL, NULL, 128, 63, 0, 0, 0, 0, 0},
	{NULL, NULL, 248, 31, 0, 0, 0, 0, 0},
	{NULL, NULL, 504, 16, 0, 0, 0, 0, 0},
	{NULL, NULL, 1016, 8, 0, 0, 0, 0, 0},
	{NULL, NULL, 2040, 4, 0, 0, 0, 0, 0},
	{NULL, NULL, 4080, 2, 0, 0, 0, 0, 0},
	{NULL, NULL, 8192 - 32, 1, 0, 0, 0, 0, 0},
	{NULL, NULL, 16384 - 32, 1, 0, 0, 0, 0, 1},
	{NULL, NULL, 32768 - 32, 1, 0, 0, 0, 0, 2},
	{NULL, NULL, 65536 - 32, 1, 0, 0, 0, 0, 3},
	{NULL, NULL, 131072 - 32, 1, 0, 0, 0, 0, 4},
	{NULL, NULL, 262144 - 32, 1, 0, 0, 0, 0, 5},
	{NULL, NULL, 0, 0, 0, 0, 0, 0, 0}
};
#else
#error you need to make a version for your pagesize
#endif

#define NBLOCKS(order)          (sizes[order].nblocks)
#define BLOCKSIZE(order)        (sizes[order].size)
#define AREASIZE(order)		(PAGE_SIZE<<(sizes[order].gfporder))


long kmalloc_init(long start_mem, long end_mem)
{
	int order;

/*
 * Check the static info array. Things will blow up terribly if it's
 * incorrect. This is a late "compile time" check.....
 */
	for (order = 0; BLOCKSIZE(order); order++) {
		if ((NBLOCKS(order) * BLOCKSIZE(order) + sizeof(struct page_descriptor)) >
		    AREASIZE(order)) {
			printk("Cannot use %d bytes out of %d in order = %d block mallocs\n",
			       (int) (NBLOCKS(order) * BLOCKSIZE(order) +
				      sizeof(struct page_descriptor)),
			        (int) AREASIZE(order),
			       BLOCKSIZE(order));
			panic("This only happens if someone messes with kmalloc");
		}
	}
	return start_mem;
}



int get_order(int size)
{
	int order;

	/* Add the size of the header */
	size += sizeof(struct block_header);
	for (order = 0; BLOCKSIZE(order); order++)
		if (size <= BLOCKSIZE(order))
			return order;
	return -1;
}

void *kmalloc(size_t size, int priority)
{
	unsigned long flags;
	unsigned long max_addr, type;
	int order, i, sz;
	struct block_header *p;
	struct page_descriptor *page, **pg;

	order = get_order(size);
	if (order < 0) {
		printk("kmalloc of too large a block (%d bytes).\n", (int) size);
		return (NULL);
	}

	max_addr = ~0UL;
	type = MF_USED;
	pg = &sizes[order].firstfree;
	if (priority & GFP_DMA) {
		max_addr = MAX_DMA_ADDRESS;
		type = MF_DMA;
		pg = &sizes[order].dmafree;
	}

	priority &= GFP_LEVEL_MASK;

/* Sanity check... */
	if (intr_count && priority != GFP_ATOMIC) {
		static int count = 0;
		if (++count < 5) {
			printk("kmalloc called nonatomically from interrupt %p\n",
			       __builtin_return_address(0));
			priority = GFP_ATOMIC;
		}
	}

	save_flags(flags);
	cli();
	page = *pg;
	if (page) {
		p = page->firstfree;
		if (p->bh_flags != MF_FREE) {
			restore_flags(flags);
			printk("Problem: block on freelist at %08lx isn't free.\n", (long) p);
			return NULL;
		}
		goto found_it;
	}

	/* We need to get a new free page..... */

	/* sz is the size of the blocks we're dealing with */
	sz = BLOCKSIZE(order);

	/* This can be done with ints on: This is private to this invocation */
	page = (struct page_descriptor *) __get_free_pages(priority & GFP_LEVEL_MASK,
			sizes[order].gfporder, max_addr);

	if (!page) {
		static unsigned long last = 0;
		if (last + 10 * HZ < jiffies) {
			last = jiffies;
			printk("Couldn't get a free page.....\n");
		}
		return NULL;
	}
	sizes[order].npages++;

	/* Loop for all but last block: */
	for (i = NBLOCKS(order), p = BH(page + 1); i > 1; i--, p = p->bh_next) {
		p->bh_flags = MF_FREE;
		p->bh_next = BH(((long) p) + sz);
	}
	/* Last block: */
	p->bh_flags = MF_FREE;
	p->bh_next = NULL;

	page->order = order;
	page->nfree = NBLOCKS(order);
	p = BH(page+1);

	/*
	 * Now we're going to muck with the "global" freelist
	 * for this size: this should be uninterruptible
	 */
	cli();
	page->next = *pg;
	*pg = page;

found_it:
	page->firstfree = p->bh_next;
	page->nfree--;
	if (!page->nfree)
		*pg = page->next;
	restore_flags(flags);
	sizes[order].nmallocs++;
	sizes[order].nbytesmalloced += size;
	p->bh_flags = type;	/* As of now this block is officially in use */
	p->bh_length = size;
	return p + 1;		/* Pointer arithmetic: increments past header */
}

void kfree(void *ptr)
{
	int size;
	unsigned long flags;
	int order;
	register struct block_header *p;
	struct page_descriptor *page, **pg;

	if (!ptr)
		return;
	p = ((struct block_header *) ptr) - 1;
	page = PAGE_DESC(p);
	order = page->order;
	pg = &sizes[order].firstfree;
	if (p->bh_flags == MF_DMA) {
		p->bh_flags = MF_USED;
		pg = &sizes[order].dmafree;
	}

	if ((order < 0) ||
	    (order > sizeof(sizes) / sizeof(sizes[0])) ||
	    (((long) (page->next)) & ~PAGE_MASK) ||
	    (p->bh_flags != MF_USED)) {
		printk("kfree of non-kmalloced memory: %p, next= %p, order=%d\n",
		       p, page->next, page->order);
		return;
	}
	size = p->bh_length;
	p->bh_flags = MF_FREE;	/* As of now this block is officially free */
	save_flags(flags);
	cli();
	p->bh_next = page->firstfree;
	page->firstfree = p;
	page->nfree++;

	if (page->nfree == 1) {
/* Page went from full to one free block: put it on the freelist. */
		page->next = *pg;
		*pg = page;
	}
/* If page is completely free, free it */
	if (page->nfree == NBLOCKS(order)) {
		for (;;) {
			struct page_descriptor *tmp = *pg;
			if (!tmp) {
				printk("Ooops. page %p doesn't show on freelist.\n", page);
				break;
			}
			if (tmp == page) {
				*pg = page->next;
				break;
			}
			pg = &tmp->next;
		}
		sizes[order].npages--;
		free_pages((long) page, sizes[order].gfporder);
	}
	sizes[order].nfrees++;
	sizes[order].nbytesmalloced -= size;
	restore_flags(flags);
}