/* test module for layered bitmaps */

#include <linux/init.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <asm/bitops.h>
#include <asm/sizes.h>

#define VIRT_SIZE	SZ_2G
#define L1_BM_SEG_SIZE	0x8000000	/* 128MB */
#define L1_BM_NUM_SEGS	(VIRT_SIZE / L1_BM_SEG_SIZE)
#define L1_BM_BITS	L1_BM_NUM_SEGS	/* 16 bits */

#define L2_BM_BITS	(L1_BM_SEG_SIZE >> PAGE_SHIFT)
#define L2_BM_SIZE	L1_BM_SEG_SIZE
#define L2_BM_LONGS	((L2_BM_BITS + BITS_PER_LONG - 1) / BITS_PER_LONG)

static unsigned long bm_l1 = 0x0000;
static unsigned long *bm_l2;
static unsigned long next_off = 0x0;

#define start_addr 0x80000000

static unsigned long test_find_free_region(unsigned long size)
{
	int l1_off, l2_off;
	unsigned long addr = 0x0;
	unsigned int order;
	unsigned long *tmp_bm;

	if (size > L1_BM_SEG_SIZE) {
		printk(KERN_ERR "size greater than 128MB is not allowed\n");
		return -EINVAL;
	}

	order = get_order(size);

next_block:
	l1_off = find_next_zero_bit(&bm_l1, L1_BM_BITS, next_off);
	if (l1_off >= L1_BM_BITS) {
		printk(KERN_ERR "layer1 bitmap is full\n");
		return -EINVAL;
	}

	tmp_bm = bm_l2 + (l1_off * L2_BM_LONGS);
	l2_off = bitmap_find_free_region(tmp_bm, 32768 /* L2_BM_SIZE */,
					 order);

	printk(KERN_INFO "l1_off %d l2_off %d\n", l1_off, l2_off);
	if (l2_off < 0) {
		next_off = (l1_off >= L1_BM_BITS) ? 0 : (next_off + 1);
		if (bitmap_full(tmp_bm, L2_BM_SIZE /*L2_BM_BITS*/)) {
			set_bit(l1_off, &bm_l1);
		}
		printk(KERN_INFO "go to next_block %ld\n", next_off);
		goto next_block;
	}

	if (bitmap_full(tmp_bm, L2_BM_SIZE /*L2_BM_BITS*/)) {
		set_bit(l1_off, &bm_l1);
	}

	addr = (l1_off * L1_BM_SEG_SIZE) + (l2_off << PAGE_SHIFT);

	return (addr + start_addr);
}

static int __init test_alloc_init(void)
{
	/*required ulongs for storage of nr_bits */
	unsigned int size = (L2_BM_BITS + (BITS_PER_LONG - 1)) / BITS_PER_LONG;
	unsigned long addr;

	/* sixteen 128MB layer 2 bitmaps */
	bm_l2 = kzalloc(size * L1_BM_NUM_SEGS, GFP_KERNEL);
	if (!bm_l2) {
		printk(KERN_INFO "No memory...\n");
		return -EINVAL;
	}
	addr = test_find_free_region(SZ_64M);
	printk(KERN_INFO "addr is 0x%lx\n", addr);

	addr = test_find_free_region(SZ_64M + SZ_32M);
	printk(KERN_INFO "addr is 0x%lx\n", addr);

	addr = test_find_free_region(SZ_128M);
	printk(KERN_INFO "addr is 0x%lx\n", addr);

	return 0;
}

static void __exit test_alloc_exit(void)
{
	/* TODO: care to free allocations :) */
}

module_init(test_alloc_init);
module_exit(test_alloc_exit);
MODULE_LICENSE("GPL");