/*
 * 	sync_provider.c
 *
 * Copyright (c) 2004 Evgeniy Polyakov <johnpol@xxxxxxxxxxx>
 * 
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/spinlock.h>
#include <linux/blkdev.h>
#include <linux/fs.h>
#include <linux/bio.h>
#include <linux/init.h>
#include <linux/crypto.h>
#include <linux/hardirq.h>

#include <asm/scatterlist.h>

//#define SYNC_DEBUG

#ifdef SYNC_DEBUG
#define dprintk(f, a...) printk(KERN_EMERG f, ##a)
#else
#define dprintk(f, a...) do {} while(0)
#endif

#define OP_ENCRYPT		0
#define OP_DECRYPT		1

static char sync_algo[] = "aes";
static char sync_key[] = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f};
static struct crypto_tfm *tfm;

void bd_encrypt(void *src, void *dst, u64 size, void *priv)
{
	struct scatterlist s, d;
	s.page 		= virt_to_page(src);
	s.offset	= offset_in_page(src);
	s.length	= size;
	
	d.page 		= virt_to_page(dst);
	d.offset	= offset_in_page(dst);
	d.length	= size;
	
	/*
	 * A hack to fool crypto layer - it thinks that we can sleep here...
	 * Sigh.
	 *
	 * preempt_count() |= SOFTIRQ_MASK;
	 */
	
	preempt_count() |= SOFTIRQ_MASK;
	crypto_cipher_encrypt(tfm, &d, &s, size);
	preempt_count() &= ~SOFTIRQ_MASK;
}
void bd_decrypt(void *src, void *dst, u64 size, void *priv)
{
	struct scatterlist s, d;
	s.page 		= virt_to_page(src);
	s.offset	= offset_in_page(src);
	s.length	= size;
	
	d.page 		= virt_to_page(dst);
	d.offset	= offset_in_page(dst);
	d.length	= size;
	
	/*
	 * A hack to fool crypto layer - it thinks that we can sleep here...
	 * Sigh.
	 *
	 * preempt_count() |= SOFTIRQ_MASK;
	 */
	preempt_count() |= SOFTIRQ_MASK;
	crypto_cipher_decrypt(tfm, &d, &s, size);
	preempt_count() &= ~SOFTIRQ_MASK;
}

int __devinit sync_init(void)
{
	int err;

	err = -ENODEV;
	tfm = crypto_alloc_tfm(sync_algo, 0);
	if (!tfm)
	{
		dprintk("Failed to allocate %s tfm.\n", sync_algo);
		goto err_out_exit;
	}

	err = crypto_cipher_setkey(tfm, sync_key, sizeof(sync_key));
	if (err)
	{
		dprintk("Failed to set key [keylen=%d]: err=%d.\n",
				sizeof(sync_key), err);
		goto err_out_free_tfm;
	}
	
	return 0;
	
err_out_free_tfm:
	crypto_free_tfm(tfm);
err_out_exit:
	return err;
}

void __devexit sync_fini(void)
{
	crypto_free_tfm(tfm);
}

module_init(sync_init);
module_exit(sync_fini);

MODULE_AUTHOR("Evgeniy Polyakov <johnpol@xxxxxxxxxxx>");
MODULE_LICENSE("GPL");

EXPORT_SYMBOL(bd_encrypt);
EXPORT_SYMBOL(bd_decrypt);