/*
 * Cryptographic API.
 *
 * T10 Data Integrity Field CRC16 Crypto Transform
 *
 * Copyright (c) 2007 Oracle Corporation.  All rights reserved.
 * Written by Martin K. Petersen <martin.petersen@oracle.com>
 * Copyright (C) 2013 Intel Corporation
 * Author: Tim Chen <tim.c.chen@linux.intel.com>
 *
 * 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.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 */

#include <linux/types.h>
#include <linux/module.h>
#include <linux/crc-t10dif.h>
#include <crypto/internal/hash.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/kernel.h>

struct chksum_desc_ctx {
	__u16 crc;
};

/* Table generated using the following polynomium:
 * x^16 + x^15 + x^11 + x^9 + x^8 + x^7 + x^5 + x^4 + x^2 + x + 1
 * gt: 0x8bb7
 */
static const __u16 t10_dif_crc_table[256] = {
	0x0000, 0x8BB7, 0x9CD9, 0x176E, 0xB205, 0x39B2, 0x2EDC, 0xA56B,
	0xEFBD, 0x640A, 0x7364, 0xF8D3, 0x5DB8, 0xD60F, 0xC161, 0x4AD6,
	0x54CD, 0xDF7A, 0xC814, 0x43A3, 0xE6C8, 0x6D7F, 0x7A11, 0xF1A6,
	0xBB70, 0x30C7, 0x27A9, 0xAC1E, 0x0975, 0x82C2, 0x95AC, 0x1E1B,
	0xA99A, 0x222D, 0x3543, 0xBEF4, 0x1B9F, 0x9028, 0x8746, 0x0CF1,
	0x4627, 0xCD90, 0xDAFE, 0x5149, 0xF422, 0x7F95, 0x68FB, 0xE34C,
	0xFD57, 0x76E0, 0x618E, 0xEA39, 0x4F52, 0xC4E5, 0xD38B, 0x583C,
	0x12EA, 0x995D, 0x8E33, 0x0584, 0xA0EF, 0x2B58, 0x3C36, 0xB781,
	0xD883, 0x5334, 0x445A, 0xCFED, 0x6A86, 0xE131, 0xF65F, 0x7DE8,
	0x373E, 0xBC89, 0xABE7, 0x2050, 0x853B, 0x0E8C, 0x19E2, 0x9255,
	0x8C4E, 0x07F9, 0x1097, 0x9B20, 0x3E4B, 0xB5FC, 0xA292, 0x2925,
	0x63F3, 0xE844, 0xFF2A, 0x749D, 0xD1F6, 0x5A41, 0x4D2F, 0xC698,
	0x7119, 0xFAAE, 0xEDC0, 0x6677, 0xC31C, 0x48AB, 0x5FC5, 0xD472,
	0x9EA4, 0x1513, 0x027D, 0x89CA, 0x2CA1, 0xA716, 0xB078, 0x3BCF,
	0x25D4, 0xAE63, 0xB90D, 0x32BA, 0x97D1, 0x1C66, 0x0B08, 0x80BF,
	0xCA69, 0x41DE, 0x56B0, 0xDD07, 0x786C, 0xF3DB, 0xE4B5, 0x6F02,
	0x3AB1, 0xB106, 0xA668, 0x2DDF, 0x88B4, 0x0303, 0x146D, 0x9FDA,
	0xD50C, 0x5EBB, 0x49D5, 0xC262, 0x6709, 0xECBE, 0xFBD0, 0x7067,
	0x6E7C, 0xE5CB, 0xF2A5, 0x7912, 0xDC79, 0x57CE, 0x40A0, 0xCB17,
	0x81C1, 0x0A76, 0x1D18, 0x96AF, 0x33C4, 0xB873, 0xAF1D, 0x24AA,
	0x932B, 0x189C, 0x0FF2, 0x8445, 0x212E, 0xAA99, 0xBDF7, 0x3640,
	0x7C96, 0xF721, 0xE04F, 0x6BF8, 0xCE93, 0x4524, 0x524A, 0xD9FD,
	0xC7E6, 0x4C51, 0x5B3F, 0xD088, 0x75E3, 0xFE54, 0xE93A, 0x628D,
	0x285B, 0xA3EC, 0xB482, 0x3F35, 0x9A5E, 0x11E9, 0x0687, 0x8D30,
	0xE232, 0x6985, 0x7EEB, 0xF55C, 0x5037, 0xDB80, 0xCCEE, 0x4759,
	0x0D8F, 0x8638, 0x9156, 0x1AE1, 0xBF8A, 0x343D, 0x2353, 0xA8E4,
	0xB6FF, 0x3D48, 0x2A26, 0xA191, 0x04FA, 0x8F4D, 0x9823, 0x1394,
	0x5942, 0xD2F5, 0xC59B, 0x4E2C, 0xEB47, 0x60F0, 0x779E, 0xFC29,
	0x4BA8, 0xC01F, 0xD771, 0x5CC6, 0xF9AD, 0x721A, 0x6574, 0xEEC3,
	0xA415, 0x2FA2, 0x38CC, 0xB37B, 0x1610, 0x9DA7, 0x8AC9, 0x017E,
	0x1F65, 0x94D2, 0x83BC, 0x080B, 0xAD60, 0x26D7, 0x31B9, 0xBA0E,
	0xF0D8, 0x7B6F, 0x6C01, 0xE7B6, 0x42DD, 0xC96A, 0xDE04, 0x55B3
};

__u16 crc_t10dif_generic(__u16 crc, const unsigned char *buffer, size_t len)
{
	unsigned int i;

	for (i = 0 ; i < len ; i++)
		crc = (crc << 8) ^ t10_dif_crc_table[((crc >> 8) ^ buffer[i]) & 0xff];

	return crc;
}
EXPORT_SYMBOL(crc_t10dif_generic);

/*
 * Steps through buffer one byte at at time, calculates reflected
 * crc using table.
 */

static int chksum_init(struct shash_desc *desc)
{
	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);

	ctx->crc = 0;

	return 0;
}

static int chksum_update(struct shash_desc *desc, const u8 *data,
			 unsigned int length)
{
	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);

	ctx->crc = crc_t10dif_generic(ctx->crc, data, length);
	return 0;
}

static int chksum_final(struct shash_desc *desc, u8 *out)
{
	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);

	*(__u16 *)out = ctx->crc;
	return 0;
}

static int __chksum_finup(__u16 *crcp, const u8 *data, unsigned int len,
			u8 *out)
{
	*(__u16 *)out = crc_t10dif_generic(*crcp, data, len);
	return 0;
}

static int chksum_finup(struct shash_desc *desc, const u8 *data,
			unsigned int len, u8 *out)
{
	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);

	return __chksum_finup(&ctx->crc, data, len, out);
}

static int chksum_digest(struct shash_desc *desc, const u8 *data,
			 unsigned int length, u8 *out)
{
	struct chksum_desc_ctx *ctx = shash_desc_ctx(desc);

	return __chksum_finup(&ctx->crc, data, length, out);
}

static struct shash_alg alg = {
	.digestsize		=	CRC_T10DIF_DIGEST_SIZE,
	.init		=	chksum_init,
	.update		=	chksum_update,
	.final		=	chksum_final,
	.finup		=	chksum_finup,
	.digest		=	chksum_digest,
	.descsize		=	sizeof(struct chksum_desc_ctx),
	.base			=	{
		.cra_name		=	"crct10dif",
		.cra_driver_name	=	"crct10dif-generic",
		.cra_priority		=	100,
		.cra_blocksize		=	CRC_T10DIF_BLOCK_SIZE,
		.cra_module		=	THIS_MODULE,
	}
};

static int __init crct10dif_mod_init(void)
{
	int ret;

	ret = crypto_register_shash(&alg);
	return ret;
}

static void __exit crct10dif_mod_fini(void)
{
	crypto_unregister_shash(&alg);
}

module_init(crct10dif_mod_init);
module_exit(crct10dif_mod_fini);

MODULE_AUTHOR("Tim Chen <tim.c.chen@linux.intel.com>");
MODULE_DESCRIPTION("T10 DIF CRC calculation.");
MODULE_LICENSE("GPL");