/*
   * t10_pi.c - Functions for generating and verifying T10 Protection
   *	      Information.
   *
   * Copyright (C) 2007, 2008, 2014 Oracle Corporation
   * Written by: Martin K. Petersen <martin.petersen@oracle.com>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License version
   * 2 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 for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; see the file COPYING.  If not, write to
   * the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139,
   * USA.
   *
   */
  
  #include <linux/t10-pi.h>
  #include <linux/blkdev.h>
  #include <linux/crc-t10dif.h>
  #include <net/checksum.h>
  
  typedef __be16 (csum_fn) (void *, unsigned int);

  static __be16 t10_pi_crc_fn(void *data, unsigned int len)
  {
  	return cpu_to_be16(crc_t10dif(data, len));
  }
  
  static __be16 t10_pi_ip_fn(void *data, unsigned int len)
  {
  	return (__force __be16)ip_compute_csum(data, len);
  }
  
  /*
   * Type 1 and Type 2 protection use the same format: 16 bit guard tag,
   * 16 bit app tag, 32 bit reference tag. Type 3 does not define the ref
   * tag.
   */

  static blk_status_t t10_pi_generate(struct blk_integrity_iter *iter,
  		csum_fn *fn, unsigned int type)

  {
  	unsigned int i;
  
  	for (i = 0 ; i < iter->data_size ; i += iter->interval) {
  		struct t10_pi_tuple *pi = iter->prot_buf;
  
  		pi->guard_tag = fn(iter->data_buf, iter->interval);
  		pi->app_tag = 0;
  
  		if (type == 1)
  			pi->ref_tag = cpu_to_be32(lower_32_bits(iter->seed));
  		else
  			pi->ref_tag = 0;
  
  		iter->data_buf += iter->interval;
  		iter->prot_buf += sizeof(struct t10_pi_tuple);
  		iter->seed++;
  	}

  	return BLK_STS_OK;

  }

  static blk_status_t t10_pi_verify(struct blk_integrity_iter *iter,
  		csum_fn *fn, unsigned int type)

  {
  	unsigned int i;
  
  	for (i = 0 ; i < iter->data_size ; i += iter->interval) {
  		struct t10_pi_tuple *pi = iter->prot_buf;
  		__be16 csum;
  
  		switch (type) {
  		case 1:
  		case 2:

  			if (pi->app_tag == T10_PI_APP_ESCAPE)

  				goto next;
  
  			if (be32_to_cpu(pi->ref_tag) !=
  			    lower_32_bits(iter->seed)) {
  				pr_err("%s: ref tag error at location %llu " \
  				       "(rcvd %u)
  ", iter->disk_name,
  				       (unsigned long long)
  				       iter->seed, be32_to_cpu(pi->ref_tag));

  				return BLK_STS_PROTECTION;

  			}
  			break;
  		case 3:

  			if (pi->app_tag == T10_PI_APP_ESCAPE &&
  			    pi->ref_tag == T10_PI_REF_ESCAPE)

  				goto next;
  			break;
  		}
  
  		csum = fn(iter->data_buf, iter->interval);
  
  		if (pi->guard_tag != csum) {
  			pr_err("%s: guard tag error at sector %llu " \
  			       "(rcvd %04x, want %04x)
  ", iter->disk_name,
  			       (unsigned long long)iter->seed,
  			       be16_to_cpu(pi->guard_tag), be16_to_cpu(csum));

  			return BLK_STS_PROTECTION;

  		}
  
  next:
  		iter->data_buf += iter->interval;
  		iter->prot_buf += sizeof(struct t10_pi_tuple);
  		iter->seed++;
  	}

  	return BLK_STS_OK;

  }

  static blk_status_t t10_pi_type1_generate_crc(struct blk_integrity_iter *iter)

  {
  	return t10_pi_generate(iter, t10_pi_crc_fn, 1);
  }

  static blk_status_t t10_pi_type1_generate_ip(struct blk_integrity_iter *iter)

  {
  	return t10_pi_generate(iter, t10_pi_ip_fn, 1);
  }

  static blk_status_t t10_pi_type1_verify_crc(struct blk_integrity_iter *iter)

  {
  	return t10_pi_verify(iter, t10_pi_crc_fn, 1);
  }

  static blk_status_t t10_pi_type1_verify_ip(struct blk_integrity_iter *iter)

  {
  	return t10_pi_verify(iter, t10_pi_ip_fn, 1);
  }

  static blk_status_t t10_pi_type3_generate_crc(struct blk_integrity_iter *iter)

  {
  	return t10_pi_generate(iter, t10_pi_crc_fn, 3);
  }

  static blk_status_t t10_pi_type3_generate_ip(struct blk_integrity_iter *iter)

  {
  	return t10_pi_generate(iter, t10_pi_ip_fn, 3);
  }

  static blk_status_t t10_pi_type3_verify_crc(struct blk_integrity_iter *iter)

  {
  	return t10_pi_verify(iter, t10_pi_crc_fn, 3);
  }

  static blk_status_t t10_pi_type3_verify_ip(struct blk_integrity_iter *iter)

  {
  	return t10_pi_verify(iter, t10_pi_ip_fn, 3);
  }

  const struct blk_integrity_profile t10_pi_type1_crc = {

  	.name			= "T10-DIF-TYPE1-CRC",
  	.generate_fn		= t10_pi_type1_generate_crc,
  	.verify_fn		= t10_pi_type1_verify_crc,

  };
  EXPORT_SYMBOL(t10_pi_type1_crc);

  const struct blk_integrity_profile t10_pi_type1_ip = {

  	.name			= "T10-DIF-TYPE1-IP",
  	.generate_fn		= t10_pi_type1_generate_ip,
  	.verify_fn		= t10_pi_type1_verify_ip,

  };
  EXPORT_SYMBOL(t10_pi_type1_ip);

  const struct blk_integrity_profile t10_pi_type3_crc = {

  	.name			= "T10-DIF-TYPE3-CRC",
  	.generate_fn		= t10_pi_type3_generate_crc,
  	.verify_fn		= t10_pi_type3_verify_crc,

  };
  EXPORT_SYMBOL(t10_pi_type3_crc);

  const struct blk_integrity_profile t10_pi_type3_ip = {

  	.name			= "T10-DIF-TYPE3-IP",
  	.generate_fn		= t10_pi_type3_generate_ip,
  	.verify_fn		= t10_pi_type3_verify_ip,

  };
  EXPORT_SYMBOL(t10_pi_type3_ip);