/*
 * sd_dif.c - SCSI Data Integrity Field
 *
 * Copyright (C) 2007, 2008 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/blkdev.h>
#include <linux/crc-t10dif.h>

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_dbg.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_driver.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_ioctl.h>
#include <scsi/scsicam.h>

#include <net/checksum.h>

#include "sd.h"

typedef __u16 (csum_fn) (void *, unsigned int);

static __u16 sd_dif_crc_fn(void *data, unsigned int len)
{
        return cpu_to_be16(crc_t10dif(data, len));
}

static __u16 sd_dif_ip_fn(void *data, unsigned int len)
{
        return 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.
 */
static void sd_dif_type1_generate(struct blk_integrity_exchg *bix, csum_fn *fn)
{
        void *buf = bix->data_buf;
        struct sd_dif_tuple *sdt = bix->prot_buf;
        sector_t sector = bix->sector;
        unsigned int i;

        for (i = 0 ; i < bix->data_size ; i += bix->sector_size, sdt++) {
                sdt->guard_tag = fn(buf, bix->sector_size);
                sdt->ref_tag = cpu_to_be32(sector & 0xffffffff);
                sdt->app_tag = 0;

                buf += bix->sector_size;
                sector++;
        }
}

static void sd_dif_type1_generate_crc(struct blk_integrity_exchg *bix)
{
        sd_dif_type1_generate(bix, sd_dif_crc_fn);
}

static void sd_dif_type1_generate_ip(struct blk_integrity_exchg *bix)
{
        sd_dif_type1_generate(bix, sd_dif_ip_fn);
}

static int sd_dif_type1_verify(struct blk_integrity_exchg *bix, csum_fn *fn)
{
        void *buf = bix->data_buf;
        struct sd_dif_tuple *sdt = bix->prot_buf;
        sector_t sector = bix->sector;
        unsigned int i;
        __u16 csum;

        for (i = 0 ; i < bix->data_size ; i += bix->sector_size, sdt++) {
                /* Unwritten sectors */
                if (sdt->app_tag == 0xffff)
                        return 0;

                /* Bad ref tag received from disk */
                if (sdt->ref_tag == 0xffffffff) {
                        printk(KERN_ERR
                               "%s: bad phys ref tag on sector %lu\n",
                               bix->disk_name, (unsigned long)sector);
                        return -EIO;
                }

                if (be32_to_cpu(sdt->ref_tag) != (sector & 0xffffffff)) {
                        printk(KERN_ERR
                               "%s: ref tag error on sector %lu (rcvd %u)\n",
                               bix->disk_name, (unsigned long)sector,
                               be32_to_cpu(sdt->ref_tag));
                        return -EIO;
                }

                csum = fn(buf, bix->sector_size);

                if (sdt->guard_tag != csum) {
                        printk(KERN_ERR "%s: guard tag error on sector %lu " \
                               "(rcvd %04x, data %04x)\n", bix->disk_name,
                               (unsigned long)sector,
                               be16_to_cpu(sdt->guard_tag), be16_to_cpu(csum));
                        return -EIO;
                }

                buf += bix->sector_size;
                sector++;
        }

        return 0;
}

static int sd_dif_type1_verify_crc(struct blk_integrity_exchg *bix)
{
        return sd_dif_type1_verify(bix, sd_dif_crc_fn);
}

static int sd_dif_type1_verify_ip(struct blk_integrity_exchg *bix)
{
        return sd_dif_type1_verify(bix, sd_dif_ip_fn);
}

/*
 * Functions for interleaving and deinterleaving application tags
 */
static void sd_dif_type1_set_tag(void *prot, void *tag_buf, unsigned int sectors)
{
        struct sd_dif_tuple *sdt = prot;
        u8 *tag = tag_buf;
        unsigned int i, j;

        for (i = 0, j = 0 ; i < sectors ; i++, j += 2, sdt++) {
                sdt->app_tag = tag[j] << 8 | tag[j+1];
                BUG_ON(sdt->app_tag == 0xffff);
        }
}

static void sd_dif_type1_get_tag(void *prot, void *tag_buf, unsigned int sectors)
{
        struct sd_dif_tuple *sdt = prot;
        u8 *tag = tag_buf;
        unsigned int i, j;

        for (i = 0, j = 0 ; i < sectors ; i++, j += 2, sdt++) {
                tag[j] = (sdt->app_tag & 0xff00) >> 8;
                tag[j+1] = sdt->app_tag & 0xff;
        }
}

static struct blk_integrity dif_type1_integrity_crc = {
        .name                   = "T10-DIF-TYPE1-CRC",
        .generate_fn            = sd_dif_type1_generate_crc,
        .verify_fn              = sd_dif_type1_verify_crc,
        .get_tag_fn             = sd_dif_type1_get_tag,
        .set_tag_fn             = sd_dif_type1_set_tag,
        .tuple_size             = sizeof(struct sd_dif_tuple),
        .tag_size               = 0,
};

static struct blk_integrity dif_type1_integrity_ip = {
        .name                   = "T10-DIF-TYPE1-IP",
        .generate_fn            = sd_dif_type1_generate_ip,
        .verify_fn              = sd_dif_type1_verify_ip,
        .get_tag_fn             = sd_dif_type1_get_tag,
        .set_tag_fn             = sd_dif_type1_set_tag,
        .tuple_size             = sizeof(struct sd_dif_tuple),
        .tag_size               = 0,
};


/*
 * Type 3 protection has a 16-bit guard tag and 16 + 32 bits of opaque
 * tag space.
 */
static void sd_dif_type3_generate(struct blk_integrity_exchg *bix, csum_fn *fn)
{
        void *buf = bix->data_buf;
        struct sd_dif_tuple *sdt = bix->prot_buf;
        unsigned int i;

        for (i = 0 ; i < bix->data_size ; i += bix->sector_size, sdt++) {
                sdt->guard_tag = fn(buf, bix->sector_size);
                sdt->ref_tag = 0;
                sdt->app_tag = 0;

                buf += bix->sector_size;
        }
}

static void sd_dif_type3_generate_crc(struct blk_integrity_exchg *bix)
{
        sd_dif_type3_generate(bix, sd_dif_crc_fn);
}

static void sd_dif_type3_generate_ip(struct blk_integrity_exchg *bix)
{
        sd_dif_type3_generate(bix, sd_dif_ip_fn);
}

static int sd_dif_type3_verify(struct blk_integrity_exchg *bix, csum_fn *fn)
{
        void *buf = bix->data_buf;
        struct sd_dif_tuple *sdt = bix->prot_buf;
        sector_t sector = bix->sector;
        unsigned int i;
        __u16 csum;

        for (i = 0 ; i < bix->data_size ; i += bix->sector_size, sdt++) {
                /* Unwritten sectors */
                if (sdt->app_tag == 0xffff && sdt->ref_tag == 0xffffffff)
                        return 0;

                csum = fn(buf, bix->sector_size);

                if (sdt->guard_tag != csum) {
                        printk(KERN_ERR "%s: guard tag error on sector %lu " \
                               "(rcvd %04x, data %04x)\n", bix->disk_name,
                               (unsigned long)sector,
                               be16_to_cpu(sdt->guard_tag), be16_to_cpu(csum));
                        return -EIO;
                }

                buf += bix->sector_size;
                sector++;
        }

        return 0;
}

static int sd_dif_type3_verify_crc(struct blk_integrity_exchg *bix)
{
        return sd_dif_type3_verify(bix, sd_dif_crc_fn);
}

static int sd_dif_type3_verify_ip(struct blk_integrity_exchg *bix)
{
        return sd_dif_type3_verify(bix, sd_dif_ip_fn);
}

static void sd_dif_type3_set_tag(void *prot, void *tag_buf, unsigned int sectors)
{
        struct sd_dif_tuple *sdt = prot;
        u8 *tag = tag_buf;
        unsigned int i, j;

        for (i = 0, j = 0 ; i < sectors ; i++, j += 6, sdt++) {
                sdt->app_tag = tag[j] << 8 | tag[j+1];
                sdt->ref_tag = tag[j+2] << 24 | tag[j+3] << 16 |
                        tag[j+4] << 8 | tag[j+5];
        }
}

static void sd_dif_type3_get_tag(void *prot, void *tag_buf, unsigned int sectors)
{
        struct sd_dif_tuple *sdt = prot;
        u8 *tag = tag_buf;
        unsigned int i, j;

        for (i = 0, j = 0 ; i < sectors ; i++, j += 2, sdt++) {
                tag[j] = (sdt->app_tag & 0xff00) >> 8;
                tag[j+1] = sdt->app_tag & 0xff;
                tag[j+2] = (sdt->ref_tag & 0xff000000) >> 24;
                tag[j+3] = (sdt->ref_tag & 0xff0000) >> 16;
                tag[j+4] = (sdt->ref_tag & 0xff00) >> 8;
                tag[j+5] = sdt->ref_tag & 0xff;
                BUG_ON(sdt->app_tag == 0xffff || sdt->ref_tag == 0xffffffff);
        }
}

static struct blk_integrity dif_type3_integrity_crc = {
        .name                   = "T10-DIF-TYPE3-CRC",
        .generate_fn            = sd_dif_type3_generate_crc,
        .verify_fn              = sd_dif_type3_verify_crc,
        .get_tag_fn             = sd_dif_type3_get_tag,
        .set_tag_fn             = sd_dif_type3_set_tag,
        .tuple_size             = sizeof(struct sd_dif_tuple),
        .tag_size               = 0,
};

static struct blk_integrity dif_type3_integrity_ip = {
        .name                   = "T10-DIF-TYPE3-IP",
        .generate_fn            = sd_dif_type3_generate_ip,
        .verify_fn              = sd_dif_type3_verify_ip,
        .get_tag_fn             = sd_dif_type3_get_tag,
        .set_tag_fn             = sd_dif_type3_set_tag,
        .tuple_size             = sizeof(struct sd_dif_tuple),
        .tag_size               = 0,
};

/*
 * Configure exchange of protection information between OS and HBA.
 */
void sd_dif_config_host(struct scsi_disk *sdkp)
{
        struct scsi_device *sdp = sdkp->device;
        struct gendisk *disk = sdkp->disk;
        u8 type = sdkp->protection_type;
        int dif, dix;

        dif = scsi_host_dif_capable(sdp->host, type);
        dix = scsi_host_dix_capable(sdp->host, type);

        if (!dix && scsi_host_dix_capable(sdp->host, 0)) {
                dif = 0; dix = 1;
        }

        if (!dix)
                return;

        /* Enable DMA of protection information */
        if (scsi_host_get_guard(sdkp->device->host) & SHOST_DIX_GUARD_IP)
                if (type == SD_DIF_TYPE3_PROTECTION)
                        blk_integrity_register(disk, &dif_type3_integrity_ip);
                else
                        blk_integrity_register(disk, &dif_type1_integrity_ip);
        else
                if (type == SD_DIF_TYPE3_PROTECTION)
                        blk_integrity_register(disk, &dif_type3_integrity_crc);
                else
                        blk_integrity_register(disk, &dif_type1_integrity_crc);

        sd_printk(KERN_NOTICE, sdkp,
                  "Enabling DIX %s protection\n", disk->integrity->name);

        /* Signal to block layer that we support sector tagging */
        if (dif && type && sdkp->ATO) {
                if (type == SD_DIF_TYPE3_PROTECTION)
                        disk->integrity->tag_size = sizeof(u16) + sizeof(u32);
                else
                        disk->integrity->tag_size = sizeof(u16);

                sd_printk(KERN_NOTICE, sdkp, "DIF application tag size %u\n",
                          disk->integrity->tag_size);
        }
}

/*
 * The virtual start sector is the one that was originally submitted
 * by the block layer.  Due to partitioning, MD/DM cloning, etc. the
 * actual physical start sector is likely to be different.  Remap
 * protection information to match the physical LBA.
 *
 * From a protocol perspective there's a slight difference between
 * Type 1 and 2.  The latter uses 32-byte CDBs exclusively, and the
 * reference tag is seeded in the CDB.  This gives us the potential to
 * avoid virt->phys remapping during write.  However, at read time we
 * don't know whether the virt sector is the same as when we wrote it
 * (we could be reading from real disk as opposed to MD/DM device.  So
 * we always remap Type 2 making it identical to Type 1.
 *
 * Type 3 does not have a reference tag so no remapping is required.
 */
int sd_dif_prepare(struct request *rq, sector_t hw_sector, unsigned int sector_sz)
{
        const int tuple_sz = sizeof(struct sd_dif_tuple);
        struct bio *bio;
        struct scsi_disk *sdkp;
        struct sd_dif_tuple *sdt;
        unsigned int i, j;
        u32 phys, virt;

        /* Already remapped? */
        if (rq->cmd_flags & REQ_INTEGRITY)
                return 0;

        sdkp = rq->bio->bi_bdev->bd_disk->private_data;

        if (sdkp->protection_type == SD_DIF_TYPE3_PROTECTION)
                return 0;

        rq->cmd_flags |= REQ_INTEGRITY;
        phys = hw_sector & 0xffffffff;

        __rq_for_each_bio(bio, rq) {
                struct bio_vec *iv;

                virt = bio->bi_integrity->bip_sector & 0xffffffff;

                bip_for_each_vec(iv, bio->bi_integrity, i) {
                        sdt = kmap_atomic(iv->bv_page, KM_USER0)
                                + iv->bv_offset;

                        for (j = 0 ; j < iv->bv_len ; j += tuple_sz, sdt++) {

                                if (be32_to_cpu(sdt->ref_tag) != virt)
                                        goto error;

                                sdt->ref_tag = cpu_to_be32(phys);
                                virt++;
                                phys++;
                        }

                        kunmap_atomic(sdt, KM_USER0);
                }
        }

        return 0;

error:
        kunmap_atomic(sdt, KM_USER0);
        sd_printk(KERN_ERR, sdkp, "%s: virt %u, phys %u, ref %u, app %4x\n",
                  __func__, virt, phys, be32_to_cpu(sdt->ref_tag),
                  be16_to_cpu(sdt->app_tag));

        return -EILSEQ;
}

/*
 * Remap physical sector values in the reference tag to the virtual
 * values expected by the block layer.
 */
void sd_dif_complete(struct scsi_cmnd *scmd, unsigned int good_bytes)
{
        const int tuple_sz = sizeof(struct sd_dif_tuple);
        struct scsi_disk *sdkp;
        struct bio *bio;
        struct sd_dif_tuple *sdt;
        unsigned int i, j, sectors, sector_sz;
        u32 phys, virt;

        sdkp = scsi_disk(scmd->request->rq_disk);

        if (sdkp->protection_type == SD_DIF_TYPE3_PROTECTION || good_bytes == 0)
                return;

        sector_sz = scmd->device->sector_size;
        sectors = good_bytes / sector_sz;

        phys = blk_rq_pos(scmd->request) & 0xffffffff;
        if (sector_sz == 4096)
                phys >>= 3;

        __rq_for_each_bio(bio, scmd->request) {
                struct bio_vec *iv;

                virt = bio->bi_integrity->bip_sector & 0xffffffff;

                bip_for_each_vec(iv, bio->bi_integrity, i) {
                        sdt = kmap_atomic(iv->bv_page, KM_USER0)
                                + iv->bv_offset;

                        for (j = 0 ; j < iv->bv_len ; j += tuple_sz, sdt++) {

                                if (sectors == 0) {
                                        kunmap_atomic(sdt, KM_USER0);
                                        return;
                                }

                                if (be32_to_cpu(sdt->ref_tag) != phys &&
                                    sdt->app_tag != 0xffff)
                                        sdt->ref_tag = 0xffffffff; /* Bad ref */
                                else
                                        sdt->ref_tag = cpu_to_be32(virt);

                                virt++;
                                phys++;
                                sectors--;
                        }

                        kunmap_atomic(sdt, KM_USER0);
                }
        }
}