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

  #include <linux/kernel.h>
  
  struct chksum_desc_ctx {
  	__u16 crc;
  };

  /*
   * 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 crc, const u8 *data, unsigned int len, u8 *out)

  {

  	*(__u16 *)out = crc_t10dif_generic(crc, 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)
  {

  	return __chksum_finup(0, 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)
  {

  	return crypto_register_shash(&alg);

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

  subsys_initcall(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");

  MODULE_ALIAS_CRYPTO("crct10dif");

  MODULE_ALIAS_CRYPTO("crct10dif-generic");