/*
 * 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)\n", 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)\n", 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);