/* GPL HEADER START
   *
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 only,
   * as published by the Free Software Foundation.
   *
   * 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 version 2 for more details (a copy is included
   * in the LICENSE file that accompanied this code).
   *
   * You should have received a copy of the GNU General Public License
   * version 2 along with this program; If not, see http://www.gnu.org/licenses
   *
   * Please  visit http://www.xyratex.com/contact if you need additional
   * information or have any questions.
   *
   * GPL HEADER END
   */
  
  /*
   * Copyright 2012 Xyratex Technology Limited
   */
  
  /*
   * This is crypto api shash wrappers to crc32_le.
   */
  
  #include <linux/crc32.h>
  #include <crypto/internal/hash.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/string.h>
  #include <linux/kernel.h>
  
  #define CHKSUM_BLOCK_SIZE	1
  #define CHKSUM_DIGEST_SIZE	4
  
  static u32 __crc32_le(u32 crc, unsigned char const *p, size_t len)
  {
  	return crc32_le(crc, p, len);
  }
  
  /** No default init with ~0 */
  static int crc32_cra_init(struct crypto_tfm *tfm)
  {
  	u32 *key = crypto_tfm_ctx(tfm);
  
  	*key = 0;
  
  	return 0;
  }
  
  
  /*
   * Setting the seed allows arbitrary accumulators and flexible XOR policy
   * If your algorithm starts with ~0, then XOR with ~0 before you set
   * the seed.
   */
  static int crc32_setkey(struct crypto_shash *hash, const u8 *key,
  			unsigned int keylen)
  {
  	u32 *mctx = crypto_shash_ctx(hash);
  
  	if (keylen != sizeof(u32)) {
  		crypto_shash_set_flags(hash, CRYPTO_TFM_RES_BAD_KEY_LEN);
  		return -EINVAL;
  	}
  	*mctx = le32_to_cpup((__le32 *)key);
  	return 0;
  }
  
  static int crc32_init(struct shash_desc *desc)
  {
  	u32 *mctx = crypto_shash_ctx(desc->tfm);
  	u32 *crcp = shash_desc_ctx(desc);
  
  	*crcp = *mctx;
  
  	return 0;
  }
  
  static int crc32_update(struct shash_desc *desc, const u8 *data,
  			unsigned int len)
  {
  	u32 *crcp = shash_desc_ctx(desc);
  
  	*crcp = __crc32_le(*crcp, data, len);
  	return 0;
  }
  
  /* No final XOR 0xFFFFFFFF, like crc32_le */
  static int __crc32_finup(u32 *crcp, const u8 *data, unsigned int len,
  			 u8 *out)
  {
  	*(__le32 *)out = cpu_to_le32(__crc32_le(*crcp, data, len));
  	return 0;
  }
  
  static int crc32_finup(struct shash_desc *desc, const u8 *data,
  		       unsigned int len, u8 *out)
  {
  	return __crc32_finup(shash_desc_ctx(desc), data, len, out);
  }
  
  static int crc32_final(struct shash_desc *desc, u8 *out)
  {
  	u32 *crcp = shash_desc_ctx(desc);
  
  	*(__le32 *)out = cpu_to_le32p(crcp);
  	return 0;
  }
  
  static int crc32_digest(struct shash_desc *desc, const u8 *data,
  			unsigned int len, u8 *out)
  {
  	return __crc32_finup(crypto_shash_ctx(desc->tfm), data, len,
  			     out);
  }
  static struct shash_alg alg = {
  	.setkey		= crc32_setkey,
  	.init		= crc32_init,
  	.update		= crc32_update,
  	.final		= crc32_final,
  	.finup		= crc32_finup,
  	.digest		= crc32_digest,
  	.descsize	= sizeof(u32),
  	.digestsize	= CHKSUM_DIGEST_SIZE,
  	.base		= {
  		.cra_name		= "crc32",
  		.cra_driver_name	= "crc32-table",
  		.cra_priority		= 100,
  		.cra_blocksize		= CHKSUM_BLOCK_SIZE,
  		.cra_ctxsize		= sizeof(u32),
  		.cra_module		= THIS_MODULE,
  		.cra_init		= crc32_cra_init,
  	}
  };
  
  static int __init crc32_mod_init(void)
  {
  	return crypto_register_shash(&alg);
  }
  
  static void __exit crc32_mod_fini(void)
  {
  	crypto_unregister_shash(&alg);
  }
  
  module_init(crc32_mod_init);
  module_exit(crc32_mod_fini);
  
  MODULE_AUTHOR("Alexander Boyko <alexander_boyko@xyratex.com>");
  MODULE_DESCRIPTION("CRC32 calculations wrapper for lib/crc32");
  MODULE_LICENSE("GPL");